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Security hardening

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Red Hat Enterprise Linux 9

Enhancing security of Red Hat Enterprise Linux 9 systems

Red Hat Customer Content Services

Abstract

Learn the processes and practices for securing Red Hat Enterprise Linux servers and workstations against local and remote intrusion, exploitation, and malicious activity. By using these approaches and tools, you can create a more secure computing environment for the data center, workplace, and home.

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Chapter 1. Securing RHEL during installation

Security begins even before you start the installation of Red Hat Enterprise Linux. Configuring your system securely from the beginning makes it easier to implement additional security settings later.

1.1. Disk partitioning

The recommended practices for disk partitioning differ for installations on bare-metal machines and for virtualized or cloud environments that support adjusting virtual disk hardware and file systems containing already-installed operating systems.

To ensure separation and protection of data on bare-metal installations, create separate partitions for the /boot, /, /home, /tmp, and /var/tmp/ directories:

/boot
This partition is the first partition that is read by the system during boot up. The boot loader and kernel images that are used to boot your system into Red Hat Enterprise Linux 9 are stored in this partition. This partition should not be encrypted. If this partition is included in / and that partition is encrypted or otherwise becomes unavailable then your system is not able to boot.
/home
When user data (/home) is stored in / instead of in a separate partition, the partition can fill up causing the operating system to become unstable. Also, when upgrading your system to the next version of Red Hat Enterprise Linux 9 it is a lot easier when you can keep your data in the /home partition as it is not be overwritten during installation. If the root partition (/) becomes corrupt your data could be lost forever. By using a separate partition there is slightly more protection against data loss. You can also target this partition for frequent backups.
/tmp and /var/tmp/
Both the /tmp and /var/tmp/ directories are used to store data that does not need to be stored for a long period of time. However, if a lot of data floods one of these directories it can consume all of your storage space. If this happens and these directories are stored within / then your system could become unstable and crash. For this reason, moving these directories into their own partitions is a good idea.

For virtual machines or cloud instances, the separate /boot, /home, /tmp, and /var/tmp partitions are optional because you can increase the virtual disk size and the / partition if it begins to fill up. Set up monitoring to regularly check the / partition usage so that it does not fill up before you increase the virtual disk size accordingly.

Note

During the installation process, you have an option to encrypt partitions. You must supply a passphrase. This passphrase serves as a key to unlock the bulk encryption key, which is used to secure the partition’s data.

1.2. Restricting network connectivity during the installation process

When installing Red Hat Enterprise Linux 9, the installation medium represents a snapshot of the system at a particular time. Because of this, it may not be up-to-date with the latest security fixes and may be vulnerable to certain issues that were fixed only after the system provided by the installation medium was released.

When installing a potentially vulnerable operating system, always limit exposure only to the closest necessary network zone. The safest choice is the “no network” zone, which means to leave your machine disconnected during the installation process. In some cases, a LAN or intranet connection is sufficient while the Internet connection is the riskiest. To follow the best security practices, choose the closest zone with your repository while installing Red Hat Enterprise Linux 9 from a network.

1.3. Installing the minimum amount of packages required

It is best practice to install only the packages you will use because each piece of software on your computer could possibly contain a vulnerability. If you are installing from the DVD media, take the opportunity to select exactly what packages you want to install during the installation. If you find you need another package, you can always add it to the system later.

1.4. Post-installation procedures

The following steps are the security-related procedures that should be performed immediately after installation of Red Hat Enterprise Linux 9.

  • Update your system. Enter the following command as root:

    # dnf update
  • Even though the firewall service, firewalld, is automatically enabled with the installation of Red Hat Enterprise Linux, it might be explicitly disabled, for example, in the Kickstart configuration. In such a case, re-enable the firewall.

    To start firewalld enter the following commands as root:

    # systemctl start firewalld
    # systemctl enable firewalld
  • To enhance security, disable services you do not need. For example, if no printers are installed on your computer, disable the cups service by using the following command:

    # systemctl disable cups

    To review active services, enter the following command:

    $ systemctl list-units | grep service

Chapter 2. Switching RHEL to FIPS mode

To enable the cryptographic module self-checks mandated by the Federal Information Processing Standard (FIPS) 140-3, you must operate RHEL 9 in FIPS mode. Starting the installation in FIPS mode is the recommended method if you aim for FIPS compliance.

Note

The cryptographic modules of RHEL 9 are not yet certified for the FIPS 140-3 requirements.

2.1. Federal Information Processing Standards 140 and FIPS mode

The Federal Information Processing Standards (FIPS) Publication 140 is a series of computer security standards developed by the National Institute of Standards and Technology (NIST) to ensure the quality of cryptographic modules. The FIPS 140 standard ensures that cryptographic tools implement their algorithms correctly. Runtime cryptographic algorithm and integrity self-tests are some of the mechanisms to ensure a system uses cryptography that meets the requirements of the standard.

To ensure that your RHEL system generates and uses all cryptographic keys only with FIPS-approved algorithms, you must switch RHEL to FIPS mode.

You can enable FIPS mode by using one of the following methods:

  • Starting the installation in FIPS mode
  • Switching the system into FIPS mode after the installation

If you aim for FIPS compliance, start the installation in FIPS mode. This avoids cryptographic key material regeneration and reevaluation of the compliance of the resulting system associated with converting already deployed systems.

To operate a FIPS-compliant system, create all cryptographic key material in FIPS mode. Furthermore, the cryptographic key material must never leave the FIPS environment unless it is securely wrapped and never unwrapped in non-FIPS environments.

Switching the system to FIPS mode by using the fips-mode-setup tool does not guarantee compliance with the FIPS 140 standard. Re-generating all cryptographic keys after setting the system to FIPS mode may not be possible. For example, in the case of an existing IdM realm with users' cryptographic keys you cannot re-generate all the keys. If you cannot start the installation in FIPS mode, always enable FIPS mode as the first step after the installation, before you make any post-installation configuration steps or install any workloads.

The fips-mode-setup tool also uses the FIPS system-wide cryptographic policy internally. But on top of what the update-crypto-policies --set FIPS command does, fips-mode-setup ensures the installation of the FIPS dracut module by using the fips-finish-install tool, it also adds the fips=1 boot option to the kernel command line and regenerates the initial RAM disk.

Furthermore, enforcement of restrictions required in FIPS mode depends on the contents of the /proc/sys/crypto/fips_enabled file. If the file contains 1, RHEL core cryptographic components switch to mode, in which they use only FIPS-approved implementations of cryptographic algorithms. If /proc/sys/crypto/fips_enabled contains 0, the cryptographic components do not enable their FIPS mode.

The FIPS system-wide cryptographic policy helps to configure higher-level restrictions. Therefore, communication protocols supporting cryptographic agility do not announce ciphers that the system refuses when selected. For example, the ChaCha20 algorithm is not FIPS-approved, and the FIPS cryptographic policy ensures that TLS servers and clients do not announce the TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 TLS cipher suite, because any attempt to use such a cipher fails.

If you operate RHEL in FIPS mode and use an application providing its own FIPS-mode-related configuration options, ignore these options and the corresponding application guidance. The system running in FIPS mode and the system-wide cryptographic policies enforce only FIPS-compliant cryptography. For example, the Node.js configuration option --enable-fips is ignored if the system runs in FIPS mode. If you use the --enable-fips option on a system not running in FIPS mode, you do not meet the FIPS-140 compliance requirements.

Note

The cryptographic modules of RHEL 9 are not yet certified for the FIPS 140-3 requirements by the National Institute of Standards and Technology (NIST) Cryptographic Module Validation Program (CMVP). You can see the validation status of cryptographic modules FIPS 140-2 and FIPS 140-3 section in the Compliance Activities and Government Standards Knowledgebase article.

Warning

A RHEL 9.2 and later system running in FIPS mode enforces that any TLS 1.2 connection must use the Extended Master Secret (EMS) extension (RFC 7627) as requires the FIPS 140-3 standard. Thus, legacy clients not supporting EMS or TLS 1.3 cannot connect to RHEL 9 servers running in FIPS mode, RHEL 9 clients in FIPS mode cannot connect to servers that support only TLS 1.2 without EMS. See TLS Extension "Extended Master Secret" enforced with Red Hat Enterprise Linux 9.2

2.2. Installing the system with FIPS mode enabled

To enable the cryptographic module self-checks mandated by the Federal Information Processing Standard (FIPS) 140, enable FIPS mode during the system installation.

Important

Only enabling FIPS mode during the RHEL installation ensures that the system generates all keys with FIPS-approved algorithms and continuous monitoring tests in place.

Warning

After you complete the setup of FIPS mode, you cannot switch off FIPS mode without putting the system into an inconsistent state. If your scenario requires this change, the only correct way is a complete re-installation of the system.

Procedure

  1. Add the fips=1 option to the kernel command line during the system installation.
  2. During the software selection stage, do not install any third-party software.
  3. After the installation, the system starts in FIPS mode automatically.

Verification

  • After the system starts, check that FIPS mode is enabled:

    $ fips-mode-setup --check
    FIPS mode is enabled.

Additional resources

2.3. Switching the system to FIPS mode

The system-wide cryptographic policies contain a policy level that enables cryptographic algorithms in accordance with the requirements by the Federal Information Processing Standard (FIPS) Publication 140. The fips-mode-setup tool that enables or disables FIPS mode internally uses the FIPS system-wide cryptographic policy.

Switching the system to FIPS mode by using the FIPS system-wide cryptographic policy does not guarantee compliance with the FIPS 140 standard. Re-generating all cryptographic keys after setting the system to FIPS mode may not be possible. For example, in the case of an existing IdM realm with users' cryptographic keys you cannot re-generate all the keys.

Important

Only enabling FIPS mode during the RHEL installation ensures that the system generates all keys with FIPS-approved algorithms and continuous monitoring tests in place.

The fips-mode-setup tool uses the FIPS policy internally. But on top of what the update-crypto-policies command with the --set FIPS option does, fips-mode-setup ensures the installation of the FIPS dracut module by using the fips-finish-install tool, it also adds the fips=1 boot option to the kernel command line and regenerates the initial RAM disk.

Warning

After you complete the setup of FIPS mode, you cannot switch off FIPS mode without putting the system into an inconsistent state. If your scenario requires this change, the only correct way is a complete re-installation of the system.

Note

The cryptographic modules of RHEL 9 are not yet certified for the FIPS 140-3 requirements.

Procedure

  1. To switch the system to FIPS mode:

    # fips-mode-setup --enable
    Kernel initramdisks are being regenerated. This might take some time.
    Setting system policy to FIPS
    Note: System-wide crypto policies are applied on application start-up.
    It is recommended to restart the system for the change of policies
    to fully take place.
    FIPS mode will be enabled.
    Please reboot the system for the setting to take effect.
  2. Restart your system to allow the kernel to switch to FIPS mode:

    # reboot

Verification

  • After the restart, you can check the current state of FIPS mode:

    # fips-mode-setup --check
    FIPS mode is enabled.

Additional resources

2.4. Enabling FIPS mode in a container

To enable the full set of cryptographic module self-checks mandated by the Federal Information Processing Standard Publication 140-2 (FIPS mode), the host system kernel must be running in FIPS mode. The podman utility automatically enables FIPS mode on supported containers.

The fips-mode-setup command does not work correctly in containers, and it cannot be used to enable or check FIPS mode in this scenario.

Note

The cryptographic modules of RHEL 9 are not yet certified for the FIPS 140-3 requirements.

Prerequisites

  • The host system must be in FIPS mode.

Procedure

  • On systems with FIPS mode enabled, the podman utility automatically enables FIPS mode on supported containers.

2.5. List of RHEL applications using cryptography that is not compliant with FIPS 140-3

To pass all relevant cryptographic certifications, such as FIPS 140-3, use libraries from the core cryptographic components set. These libraries, except from libgcrypt, also follow the RHEL system-wide cryptographic policies.

See the RHEL core cryptographic components article for an overview of the core cryptographic components, the information on how are they selected, how are they integrated into the operating system, how do they support hardware security modules and smart cards, and how do cryptographic certifications apply to them.

List of RHEL 9 applications using cryptography that is not compliant with FIPS 140-3

Bacula
Implements the CRAM-MD5 authentication protocol.
Cyrus SASL
Uses the SCRAM-SHA-1 authentication method.
Dovecot
Uses SCRAM-SHA-1.
Emacs
Uses SCRAM-SHA-1.
FreeRADIUS
Uses MD5 and SHA-1 for authentication protocols.
Ghostscript
Custom cryptography implementation (MD5, RC4, SHA-2, AES) to encrypt and decrypt documents.
GRUB2
Supports legacy firmware protocols requiring SHA-1 and includes the libgcrypt library.
iPXE
Implements TLS stack.
Kerberos
Preserves support for SHA-1 (interoperability with Windows).
Lasso
The lasso_wsse_username_token_derive_key() key derivation function (KDF) uses SHA-1.
MariaDB, MariaDB Connector
The mysql_native_password authentication plugin uses SHA-1.
MySQL
mysql_native_password uses SHA-1.
OpenIPMI
The RAKP-HMAC-MD5 authentication method is not approved for FIPS usage and does not work in FIPS mode.
Ovmf (UEFI firmware), Edk2, shim
Full cryptographic stack (an embedded copy of the OpenSSL library).
Perl
Uses HMAC, HMAC-SHA1, HMAC-MD5, SHA-1, SHA-224,….
Pidgin
Implements DES and RC4 ciphers.
PKCS #12 file processing (OpenSSL, GnuTLS, NSS, Firefox, Java)
All uses of PKCS #12 are not FIPS-compliant, because the Key Derivation Function (KDF) used for calculating the whole-file HMAC is not FIPS-approved. As such, PKCS #12 files are considered to be plain text for the purposes of FIPS compliance. For key-transport purposes, wrap PKCS #12 (.p12) files using a FIPS-approved encryption scheme.
Poppler
Can save PDFs with signatures, passwords, and encryption based on non-allowed algorithms if they are present in the original PDF (for example MD5, RC4, and SHA-1).
PostgreSQL
Implements Blowfish, DES, and MD5. A KDF uses SHA-1.
QAT Engine
Mixed hardware and software implementation of cryptographic primitives (RSA, EC, DH, AES,…)
Ruby
Provides insecure MD5 and SHA-1 library functions.
Samba
Preserves support for RC4 and DES (interoperability with Windows).
Syslinux
BIOS passwords use SHA-1.
SWTPM
Explicitly disables FIPS mode in its OpenSSL usage.
Unbound
DNS specification requires that DNSSEC resolvers use a SHA-1-based algorithm in DNSKEY records for validation.
Valgrind
AES, SHA hashes.[1]
zip
Custom cryptography implementation (insecure PKWARE encryption algorithm) to encrypt and decrypt archives using a password.

Additional resources



[1] Re-implements in software hardware-offload operations, such as AES-NI or SHA-1 and SHA-2 on ARM.

Chapter 3. Using system-wide cryptographic policies

The system-wide cryptographic policies is a system component that configures the core cryptographic subsystems, covering the TLS, IPsec, SSH, DNSSec, and Kerberos protocols. It provides a small set of policies, which the administrator can select.

3.1. System-wide cryptographic policies

When a system-wide policy is set up, applications in RHEL follow it and refuse to use algorithms and protocols that do not meet the policy, unless you explicitly request the application to do so. That is, the policy applies to the default behavior of applications when running with the system-provided configuration but you can override it if required.

RHEL 9 contains the following predefined policies:

DEFAULT
The default system-wide cryptographic policy level offers secure settings for current threat models. It allows the TLS 1.2 and 1.3 protocols, as well as the IKEv2 and SSH2 protocols. The RSA keys and Diffie-Hellman parameters are accepted if they are at least 2048 bits long.
LEGACY
Ensures maximum compatibility with Red Hat Enterprise Linux 6 and earlier; it is less secure due to an increased attack surface. SHA-1 is allowed to be used as TLS hash, signature, and algorithm. CBC-mode ciphers are allowed to be used with SSH. Applications using GnuTLS allow certificates signed with SHA-1. It allows the TLS 1.2 and 1.3 protocols, as well as the IKEv2 and SSH2 protocols. The RSA keys and Diffie-Hellman parameters are accepted if they are at least 2048 bits long.
FUTURE

A stricter forward-looking security level intended for testing a possible future policy. This policy does not allow the use of SHA-1 in DNSSec or as an HMAC. SHA2-224 and SHA3-224 hashes are rejected. 128-bit ciphers are disabled. CBC-mode ciphers are disabled except in Kerberos. It allows the TLS 1.2 and 1.3 protocols, as well as the IKEv2 and SSH2 protocols. The RSA keys and Diffie-Hellman parameters are accepted if they are at least 3072 bits long. If your system communicates on the public internet, you might face interoperability problems.

Important

Because a cryptographic key used by a certificate on the Customer Portal API does not meet the requirements by the FUTURE system-wide cryptographic policy, the redhat-support-tool utility does not work with this policy level at the moment.

To work around this problem, use the DEFAULT cryptographic policy while connecting to the Customer Portal API.

FIPS

Conforms with the FIPS 140 requirements. The fips-mode-setup tool, which switches the RHEL system into FIPS mode, uses this policy internally. Switching to the FIPS policy does not guarantee compliance with the FIPS 140 standard. You also must re-generate all cryptographic keys after you set the system to FIPS mode. This is not possible in many scenarios.

RHEL also provides the FIPS:OSPP system-wide subpolicy, which contains further restrictions for cryptographic algorithms required by the Common Criteria (CC) certification. The system becomes less interoperable after you set this subpolicy. For example, you cannot use RSA and DH keys shorter than 3072 bits, additional SSH algorithms, and several TLS groups. Setting FIPS:OSPP also prevents connecting to Red Hat Content Delivery Network (CDN) structure. Furthermore, you cannot integrate Active Directory (AD) into the IdM deployments that use FIPS:OSPP, communication between RHEL hosts using FIPS:OSPP and AD domains might not work, or some AD accounts might not be able to authenticate.

Note

Your system is not CC-compliant after you set the FIPS:OSPP cryptographic subpolicy. The only correct way to make your RHEL system compliant with the CC standard is through the installation of the cc-config package. See the Common Criteria section in the Compliance Activities and Government Standards Knowledgebase article for a list of certified RHEL versions, validation reports, and links to CC guides.

Red Hat continuously adjusts all policy levels so that all libraries provide secure defaults, except when using the LEGACY policy. Even though the LEGACY profile does not provide secure defaults, it does not include any algorithms that are easily exploitable. As such, the set of enabled algorithms or acceptable key sizes in any provided policy may change during the lifetime of Red Hat Enterprise Linux.

Such changes reflect new security standards and new security research. If you must ensure interoperability with a specific system for the whole lifetime of Red Hat Enterprise Linux, you should opt-out from the system-wide cryptographic policies for components that interact with that system or re-enable specific algorithms using custom cryptographic policies.

The specific algorithms and ciphers described as allowed in the policy levels are available only if an application supports them:

Table 3.1. Cipher suites and protocols enabled in the cryptographic policies
 LEGACYDEFAULTFIPSFUTURE

IKEv1

no

no

no

no

3DES

no

no

no

no

RC4

no

no

no

no

DH

min. 2048-bit

min. 2048-bit

min. 2048-bit

min. 3072-bit

RSA

min. 2048-bit

min. 2048-bit

min. 2048-bit

min. 3072-bit

DSA

no

no

no

no

TLS v1.1 and older

no

no

no

no

TLS v1.2 and newer

yes

yes

yes

yes

SHA-1 in digital signatures and certificates

yes

no

no

no

CBC mode ciphers

yes

no[a]

no[b]

no[c]

Symmetric ciphers with keys < 256 bits

yes

yes

yes

no

[a] CBC ciphers are disabled for SSH
[b] CBC ciphers are disabled for all protocols except Kerberos
[c] CBC ciphers are disabled for all protocols except Kerberos

Additional resources

  • crypto-policies(7) and update-crypto-policies(8) man pages on your system

3.2. Changing the system-wide cryptographic policy

You can change the system-wide cryptographic policy on your system by using the update-crypto-policies tool and restarting your system.

Prerequisites

  • You have root privileges on the system.

Procedure

  1. Optional: Display the current cryptographic policy:

    $ update-crypto-policies --show
    DEFAULT
  2. Set the new cryptographic policy:

    # update-crypto-policies --set <POLICY>
    <POLICY>

    Replace <POLICY> with the policy or subpolicy you want to set, for example FUTURE, LEGACY or FIPS:OSPP.

  3. Restart the system:

    # reboot

Verification

  • Display the current cryptographic policy:

    $ update-crypto-policies --show
    <POLICY>

Additional resources

3.3. Switching the system-wide cryptographic policy to mode compatible with earlier releases

The default system-wide cryptographic policy in Red Hat Enterprise Linux 9 does not allow communication using older, insecure protocols. For environments that require to be compatible with Red Hat Enterprise Linux 6 and in some cases also with earlier releases, the less secure LEGACY policy level is available.

Warning

Switching to the LEGACY policy level results in a less secure system and applications.

Procedure

  1. To switch the system-wide cryptographic policy to the LEGACY level, enter the following command as root:

    # update-crypto-policies --set LEGACY
    Setting system policy to LEGACY

Additional resources

  • For the list of available cryptographic policy levels, see the update-crypto-policies(8) man page.
  • For defining custom cryptographic policies, see the Custom Policies section in the update-crypto-policies(8) man page and the Crypto Policy Definition Format section in the crypto-policies(7) man page.

3.4. Setting up system-wide cryptographic policies in the web console

You can set one of system-wide cryptographic policies and subpolicies directly in the RHEL web console interface. Besides the four predefined system-wide cryptographic policies, you can also apply the following combinations of policies and subpolicies through the graphical interface now:

DEFAULT:SHA1
The DEFAULT policy with the SHA-1 algorithm enabled.
LEGACY:AD-SUPPORT
The LEGACY policy with less secure settings that improve interoperability for Active Directory services.
FIPS:OSPP
The FIPS policy with further restrictions required by the Common Criteria for Information Technology Security Evaluation standard.
Warning

Because the FIPS:OSPP system-wide subpolicy contains further restrictions for cryptographic algorithms required by the Common Criteria (CC) certification, the system is less interoperable after you set it. For example, you cannot use RSA and DH keys shorter than 3072 bits, additional SSH algorithms, and several TLS groups. Setting FIPS:OSPP also prevents connecting to Red Hat Content Delivery Network (CDN) structure. Furthermore, you cannot integrate Active Directory (AD) into the IdM deployments that use FIPS:OSPP, communication between RHEL hosts using FIPS:OSPP and AD domains might not work, or some AD accounts might not be able to authenticate.

Note that your system is not CC-compliant after you set the FIPS:OSPP cryptographic subpolicy. The only correct way to make your RHEL system compliant with the CC standard is through the installation of the cc-config package. See the Common Criteria section in the Compliance Activities and Government Standards Knowledgebase article for a list of certified RHEL versions, validation reports, and links to CC guides hosted at the National Information Assurance Partnership (NIAP) website.

Prerequisites

Procedure

  1. Log in to the web console. For more information, see Logging in to the web console.
  2. In the Configuration card of the Overview page, click your current policy value next to Crypto policy.

    The web console: Overview

  3. In the Change crypto policy dialog window, click on the policy you want to start using on your system.

    The web console: Change the system-wide cryptographic policy

  4. Click the Apply and reboot button.

Verification

  • After the restart, log back in to web console, and check that the Crypto policy value corresponds to the one you selected. Alternatively, you can enter the update-crypto-policies --show command to display the current system-wide cryptographic policy in your terminal.

3.5. Excluding an application from following system-wide crypto policies

You can customize cryptographic settings used by your application preferably by configuring supported cipher suites and protocols directly in the application.

You can also remove a symlink related to your application from the /etc/crypto-policies/back-ends directory and replace it with your customized cryptographic settings. This configuration prevents the use of system-wide cryptographic policies for applications that use the excluded back end. Furthermore, this modification is not supported by Red Hat.

3.5.1. Examples of opting out of system-wide crypto policies

wget

To customize cryptographic settings used by the wget network downloader, use --secure-protocol and --ciphers options. For example:

$ wget --secure-protocol=TLSv1_1 --ciphers="SECURE128" https://example.com

See the HTTPS (SSL/TLS) Options section of the wget(1) man page for more information.

curl

To specify ciphers used by the curl tool, use the --ciphers option and provide a colon-separated list of ciphers as a value. For example:

$ curl https://example.com --ciphers '@SECLEVEL=0:DES-CBC3-SHA:RSA-DES-CBC3-SHA'

See the curl(1) man page for more information.

Firefox

Even though you cannot opt out of system-wide cryptographic policies in the Firefox web browser, you can further restrict supported ciphers and TLS versions in Firefox’s Configuration Editor. Type about:config in the address bar and change the value of the security.tls.version.min option as required. Setting security.tls.version.min to 1 allows TLS 1.0 as the minimum required, security.tls.version.min 2 enables TLS 1.1, and so on.

OpenSSH

To opt out of the system-wide cryptographic policies for your OpenSSH server, specify the cryptographic policy in a drop-in configuration file located in the /etc/ssh/sshd_config.d/ directory, with a two-digit number prefix smaller than 50, so that it lexicographically precedes the 50-redhat.conf file, and with a .conf suffix, for example, 49-crypto-policy-override.conf.

See the sshd_config(5) man page for more information.

To opt out of system-wide cryptographic policies for your OpenSSH client, perform one of the following tasks:

  • For a given user, override the global ssh_config with a user-specific configuration in the ~/.ssh/config file.
  • For the entire system, specify the cryptographic policy in a drop-in configuration file located in the /etc/ssh/ssh_config.d/ directory, with a two-digit number prefix smaller than 50, so that it lexicographically precedes the 50-redhat.conf file, and with a .conf suffix, for example, 49-crypto-policy-override.conf.

See the ssh_config(5) man page for more information.

Additional resources

  • update-crypto-policies(8) man page

3.6. Customizing system-wide cryptographic policies with subpolicies

Use this procedure to adjust the set of enabled cryptographic algorithms or protocols.

You can either apply custom subpolicies on top of an existing system-wide cryptographic policy or define such a policy from scratch.

The concept of scoped policies allows enabling different sets of algorithms for different back ends. You can limit each configuration directive to specific protocols, libraries, or services.

Furthermore, directives can use asterisks for specifying multiple values using wildcards.

The /etc/crypto-policies/state/CURRENT.pol file lists all settings in the currently applied system-wide cryptographic policy after wildcard expansion. To make your cryptographic policy more strict, consider using values listed in the /usr/share/crypto-policies/policies/FUTURE.pol file.

You can find example subpolicies in the /usr/share/crypto-policies/policies/modules/ directory. The subpolicy files in this directory contain also descriptions in lines that are commented out.

Procedure

  1. Checkout to the /etc/crypto-policies/policies/modules/ directory:

    # cd /etc/crypto-policies/policies/modules/
  2. Create subpolicies for your adjustments, for example:

    # touch MYCRYPTO-1.pmod
    # touch SCOPES-AND-WILDCARDS.pmod
    Important

    Use upper-case letters in file names of policy modules.

  3. Open the policy modules in a text editor of your choice and insert options that modify the system-wide cryptographic policy, for example:

    # vi MYCRYPTO-1.pmod
    min_rsa_size = 3072
    hash = SHA2-384 SHA2-512 SHA3-384 SHA3-512
    # vi SCOPES-AND-WILDCARDS.pmod
    # Disable the AES-128 cipher, all modes
    cipher = -AES-128-*
    
    # Disable CHACHA20-POLY1305 for the TLS protocol (OpenSSL, GnuTLS, NSS, and OpenJDK)
    cipher@TLS = -CHACHA20-POLY1305
    
    # Allow using the FFDHE-1024 group with the SSH protocol (libssh and OpenSSH)
    group@SSH = FFDHE-1024+
    
    # Disable all CBC mode ciphers for the SSH protocol (libssh and OpenSSH)
    cipher@SSH = -*-CBC
    
    # Allow the AES-256-CBC cipher in applications using libssh
    cipher@libssh = AES-256-CBC+
  4. Save the changes in the module files.
  5. Apply your policy adjustments to the DEFAULT system-wide cryptographic policy level:

    # update-crypto-policies --set DEFAULT:MYCRYPTO-1:SCOPES-AND-WILDCARDS
  6. To make your cryptographic settings effective for already running services and applications, restart the system:

    # reboot

Verification

  • Check that the /etc/crypto-policies/state/CURRENT.pol file contains your changes, for example:

    $ cat /etc/crypto-policies/state/CURRENT.pol | grep rsa_size
    min_rsa_size = 3072

Additional resources

3.7. Re-enabling SHA-1

The use of the SHA-1 algorithm for creating and verifying signatures is restricted in the DEFAULT cryptographic policy. If your scenario requires the use of SHA-1 for verifying existing or third-party cryptographic signatures, you can enable it by applying the SHA1 subpolicy, which RHEL 9 provides by default. Note that it weakens the security of the system.

Prerequisites

  • The system uses the DEFAULT system-wide cryptographic policy.

Procedure

  1. Apply the SHA1 subpolicy to the DEFAULT cryptographic policy:

    # update-crypto-policies --set DEFAULT:SHA1
    Setting system policy to DEFAULT:SHA1
    Note: System-wide crypto policies are applied on application start-up.
    It is recommended to restart the system for the change of policies
    to fully take place.
  2. Restart the system:

    # reboot

Verification

  • Display the current cryptographic policy:

    # update-crypto-policies --show
    DEFAULT:SHA1
Important

Switching to the LEGACY cryptographic policy by using the update-crypto-policies --set LEGACY command also enables SHA-1 for signatures. However, the LEGACY cryptographic policy makes your system much more vulnerable by also enabling other weak cryptographic algorithms. Use this workaround only for scenarios that require the enablement of other legacy cryptographic algorithms than SHA-1 signatures.

3.8. Creating and setting a custom system-wide cryptographic policy

The following steps demonstrate customizing the system-wide cryptographic policies by a complete policy file.

Procedure

  1. Create a policy file for your customizations:

    # cd /etc/crypto-policies/policies/
    # touch MYPOLICY.pol

    Alternatively, start by copying one of the four predefined policy levels:

    # cp /usr/share/crypto-policies/policies/DEFAULT.pol /etc/crypto-policies/policies/MYPOLICY.pol
  2. Edit the file with your custom cryptographic policy in a text editor of your choice to fit your requirements, for example:

    # vi /etc/crypto-policies/policies/MYPOLICY.pol
  3. Switch the system-wide cryptographic policy to your custom level:

    # update-crypto-policies --set MYPOLICY
  4. To make your cryptographic settings effective for already running services and applications, restart the system:

    # reboot

Additional resources

  • Custom Policies section in the update-crypto-policies(8) man page and the Crypto Policy Definition Format section in the crypto-policies(7) man page
  • How to customize crypto policies in RHEL Red Hat blog article

3.9. Setting a custom cryptographic policy by using the crypto_policies RHEL system role

You can use the crypto_policies system role to configure a large number of managed nodes consistently from a single control node.

Prerequisites

Procedure

  1. Create a playbook file, for example ~/playbook.yml, with the following content:

    ---
    - name: Configure crypto policies
      hosts: managed-node-01.example.com
      tasks:
        - name: Configure crypto policies
          ansible.builtin.include_role:
            name: rhel-system-roles.crypto_policies
          vars:
            - crypto_policies_policy: FUTURE
            - crypto_policies_reboot_ok: true

    You can replace the FUTURE value with your preferred crypto policy, for example: DEFAULT, LEGACY, and FIPS:OSPP.

    The crypto_policies_reboot_ok: true setting causes the system to reboot after the system role changes the cryptographic policy.

  2. Validate the playbook syntax:

    $ ansible-playbook --syntax-check ~/playbook.yml

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    $ ansible-playbook ~/playbook.yml
Warning

Because the FIPS:OSPP system-wide subpolicy contains further restrictions for cryptographic algorithms required by the Common Criteria (CC) certification, the system is less interoperable after you set it. For example, you cannot use RSA and DH keys shorter than 3072 bits, additional SSH algorithms, and several TLS groups. Setting FIPS:OSPP also prevents connecting to Red Hat Content Delivery Network (CDN) structure. Furthermore, you cannot integrate Active Directory (AD) into the IdM deployments that use FIPS:OSPP, communication between RHEL hosts using FIPS:OSPP and AD domains might not work, or some AD accounts might not be able to authenticate.

Note that your system is not CC-compliant after you set the FIPS:OSPP cryptographic subpolicy. The only correct way to make your RHEL system compliant with the CC standard is through the installation of the cc-config package. See the Common Criteria section in the Compliance Activities and Government Standards Knowledgebase article for a list of certified RHEL versions, validation reports, and links to CC guides hosted at the National Information Assurance Partnership (NIAP) website.

Verification

  1. On the control node, create another playbook named, for example, verify_playbook.yml:

    ---
    - name: Verification
      hosts: managed-node-01.example.com
      tasks:
        - name: Verify active crypto policy
          ansible.builtin.include_role:
            name: rhel-system-roles.crypto_policies
        - debug:
            var: crypto_policies_active
  2. Validate the playbook syntax:

    $ ansible-playbook --syntax-check ~/verify_playbook.yml
  3. Run the playbook:

    $ ansible-playbook ~/verify_playbook.yml
    TASK [debug] **************************
    ok: [host] => {
        "crypto_policies_active": "FUTURE"
    }

    The crypto_policies_active variable shows the policy active on the managed node.

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.crypto_policies/README.md file
  • /usr/share/doc/rhel-system-roles/crypto_policies/ directory

Chapter 4. Configuring applications to use cryptographic hardware through PKCS #11

Separating parts of your secret information about dedicated cryptographic devices, such as smart cards and cryptographic tokens for end-user authentication and hardware security modules (HSM) for server applications, provides an additional layer of security. In RHEL, support for cryptographic hardware through the PKCS #11 API is consistent across different applications, and the isolation of secrets on cryptographic hardware is not a complicated task.

4.1. Cryptographic hardware support through PKCS #11

Public-Key Cryptography Standard (PKCS) #11 defines an application programming interface (API) to cryptographic devices that hold cryptographic information and perform cryptographic functions.

PKCS #11 introduces the cryptographic token, an object that presents each hardware or software device to applications in a unified manner. Therefore, applications view devices such as smart cards, which are typically used by persons, and hardware security modules, which are typically used by computers, as PKCS #11 cryptographic tokens.

A PKCS #11 token can store various object types including a certificate; a data object; and a public, private, or secret key. These objects are uniquely identifiable through the PKCS #11 Uniform Resource Identifier (URI) scheme.

A PKCS #11 URI is a standard way to identify a specific object in a PKCS #11 module according to the object attributes. This enables you to configure all libraries and applications with the same configuration string in the form of a URI.

RHEL provides the OpenSC PKCS #11 driver for smart cards by default. However, hardware tokens and HSMs can have their own PKCS #11 modules that do not have their counterpart in the system. You can register such PKCS #11 modules with the p11-kit tool, which acts as a wrapper over the registered smart-card drivers in the system.

To make your own PKCS #11 module work on the system, add a new text file to the /etc/pkcs11/modules/ directory

You can add your own PKCS #11 module into the system by creating a new text file in the /etc/pkcs11/modules/ directory. For example, the OpenSC configuration file in p11-kit looks as follows:

$ cat /usr/share/p11-kit/modules/opensc.module
module: opensc-pkcs11.so

4.2. Using SSH keys stored on a smart card

You can use RSA and ECDSA keys stored on a smart card on OpenSSH clients. Authentication by using a smart card replaces the default password authentication.

Prerequisites

  • On the client side, the opensc package is installed and the pcscd service is running.

Procedure

  1. List all keys provided by the OpenSC PKCS #11 module including their PKCS #11 URIs and save the output to the keys.pub file:

    $ ssh-keygen -D pkcs11: > keys.pub
    $ ssh-keygen -D pkcs11:
    ssh-rsa AAAAB3NzaC1yc2E...KKZMzcQZzx pkcs11:id=%02;object=SIGN%20pubkey;token=SSH%20key;manufacturer=piv_II?module-path=/usr/lib64/pkcs11/opensc-pkcs11.so
    ecdsa-sha2-nistp256 AAA...J0hkYnnsM= pkcs11:id=%01;object=PIV%20AUTH%20pubkey;token=SSH%20key;manufacturer=piv_II?module-path=/usr/lib64/pkcs11/opensc-pkcs11.so
  2. To enable authentication using a smart card on a remote server (example.com), transfer the public key to the remote server. Use the ssh-copy-id command with keys.pub created in the previous step:

    $ ssh-copy-id -f -i keys.pub username@example.com
  3. To connect to example.com using the ECDSA key from the output of the ssh-keygen -D command in step 1, you can use just a subset of the URI, which uniquely references your key, for example:

    $ ssh -i "pkcs11:id=%01?module-path=/usr/lib64/pkcs11/opensc-pkcs11.so" example.com
    Enter PIN for 'SSH key':
    [example.com] $
  4. You can use the same URI string in the ~/.ssh/config file to make the configuration permanent:

    $ cat ~/.ssh/config
    IdentityFile "pkcs11:id=%01?module-path=/usr/lib64/pkcs11/opensc-pkcs11.so"
    $ ssh example.com
    Enter PIN for 'SSH key':
    [example.com] $

    Because OpenSSH uses the p11-kit-proxy wrapper and the OpenSC PKCS #11 module is registered to PKCS#11 Kit, you can simplify the previous commands:

    $ ssh -i "pkcs11:id=%01" example.com
    Enter PIN for 'SSH key':
    [example.com] $

If you skip the id= part of a PKCS #11 URI, OpenSSH loads all keys that are available in the proxy module. This can reduce the amount of typing required:

$ ssh -i pkcs11: example.com
Enter PIN for 'SSH key':
[example.com] $

Additional resources

4.3. Configuring applications for authentication with certificates on smart cards

Authentication by using smart cards in applications may increase security and simplify automation. You can integrate the Public Key Cryptography Standard (PKCS) #11 URIs into your application by using the following methods:

  • The Firefox web browser automatically loads the p11-kit-proxy PKCS #11 module. This means that every supported smart card in the system is automatically detected. For using TLS client authentication, no additional setup is required and keys and certificates from a smart card are automatically used when a server requests them.
  • If your application uses the GnuTLS or NSS library, it already supports PKCS #11 URIs. Also, applications that rely on the OpenSSL library can access cryptographic hardware modules, including smart cards, through the pkcs11 engine provided provided by the openssl-pkcs11 package.
  • Applications that require working with private keys on smart cards and that do not use NSS, GnuTLS, nor OpenSSL can use the p11-kit API directly to work with cryptographic hardware modules, including smart cards, rather than using the PKCS #11 API of specific PKCS #11 modules.
  • With the the wget network downloader, you can specify PKCS #11 URIs instead of paths to locally stored private keys and certificates. This might simplify creation of scripts for tasks that require safely stored private keys and certificates. For example:

    $ wget --private-key 'pkcs11:token=softhsm;id=%01;type=private?pin-value=111111' --certificate 'pkcs11:token=softhsm;id=%01;type=cert' https://example.com/
  • You can also specify PKCS #11 URI when using the curl tool:

    $ curl --key 'pkcs11:token=softhsm;id=%01;type=private?pin-value=111111' --cert 'pkcs11:token=softhsm;id=%01;type=cert' https://example.com/
    Note

    Because a PIN is a security measure that controls access to keys stored on a smart card and the configuration file contains the PIN in the plain-text form, consider additional protection to prevent an attacker from reading the PIN. For example, you can use the pin-source attribute and provide a file: URI for reading the PIN from a file. See RFC 7512: PKCS #11 URI Scheme Query Attribute Semantics for more information. Note that using a command path as a value of the pin-source attribute is not supported.

Additional resources

  • curl(1), wget(1), and p11-kit(8) man pages

4.4. Using HSMs protecting private keys in Apache

The Apache HTTP server can work with private keys stored on hardware security modules (HSMs), which helps to prevent the keys' disclosure and man-in-the-middle attacks. Note that this usually requires high-performance HSMs for busy servers.

For secure communication in the form of the HTTPS protocol, the Apache HTTP server (httpd) uses the OpenSSL library. OpenSSL does not support PKCS #11 natively. To use HSMs, you have to install the openssl-pkcs11 package, which provides access to PKCS #11 modules through the engine interface. You can use a PKCS #11 URI instead of a regular file name to specify a server key and a certificate in the /etc/httpd/conf.d/ssl.conf configuration file, for example:

SSLCertificateFile    "pkcs11:id=%01;token=softhsm;type=cert"
SSLCertificateKeyFile "pkcs11:id=%01;token=softhsm;type=private?pin-value=111111"

Install the httpd-manual package to obtain complete documentation for the Apache HTTP Server, including TLS configuration. The directives available in the /etc/httpd/conf.d/ssl.conf configuration file are described in detail in the /usr/share/httpd/manual/mod/mod_ssl.html file.

4.5. Using HSMs protecting private keys in Nginx

The Nginx HTTP server can work with private keys stored on hardware security modules (HSMs), which helps to prevent the keys' disclosure and man-in-the-middle attacks. Note that this usually requires high-performance HSMs for busy servers.

Because Nginx also uses the OpenSSL for cryptographic operations, support for PKCS #11 must go through the openssl-pkcs11 engine. Nginx currently supports only loading private keys from an HSM, and a certificate must be provided separately as a regular file. Modify the ssl_certificate and ssl_certificate_key options in the server section of the /etc/nginx/nginx.conf configuration file:

ssl_certificate     /path/to/cert.pem
ssl_certificate_key "engine:pkcs11:pkcs11:token=softhsm;id=%01;type=private?pin-value=111111";

Note that the engine:pkcs11: prefix is needed for the PKCS #11 URI in the Nginx configuration file. This is because the other pkcs11 prefix refers to the engine name.

Chapter 5. Controlling access to smart cards by using polkit

To cover possible threats that cannot be prevented by mechanisms built into smart cards, such as PINs, PIN pads, and biometrics, and for more fine-grained control, RHEL uses the polkit framework for controlling access control to smart cards.

System administrators can configure polkit to fit specific scenarios, such as smart-card access for non-privileged or non-local users or services.

5.1. Smart-card access control through polkit

The Personal Computer/Smart Card (PC/SC) protocol specifies a standard for integrating smart cards and their readers into computing systems. In RHEL, the pcsc-lite package provides middleware to access smart cards that use the PC/SC API. A part of this package, the pcscd (PC/SC Smart Card) daemon, ensures that the system can access a smart card using the PC/SC protocol.

Because access-control mechanisms built into smart cards, such as PINs, PIN pads, and biometrics, do not cover all possible threats, RHEL uses the polkit framework for more robust access control. The polkit authorization manager can grant access to privileged operations. In addition to granting access to disks, you can use polkit also to specify policies for securing smart cards. For example, you can define which users can perform which operations with a smart card.

After installing the pcsc-lite package and starting the pcscd daemon, the system enforces policies defined in the /usr/share/polkit-1/actions/ directory. The default system-wide policy is in the /usr/share/polkit-1/actions/org.debian.pcsc-lite.policy file. Polkit policy files use the XML format and the syntax is described in the polkit(8) man page.

The polkitd service monitors the /etc/polkit-1/rules.d/ and /usr/share/polkit-1/rules.d/ directories for any changes in rule files stored in these directories. The files contain authorization rules in JavaScript format. System administrators can add custom rule files in both directories, and polkitd reads them in lexical order based on their file name. If two files have the same names, then the file in /etc/polkit-1/rules.d/ is read first.

If you need to enable smart-card support when the system security services daemon (SSSD) does not run as root, you must install the sssd-polkit-rules package. The package provides polkit integration with SSSD.

Additional resources

  • polkit(8), polkitd(8), and pcscd(8) man pages on your system

5.3. Displaying more detailed information about polkit authorization to PC/SC

In the default configuration, the polkit authorization framework sends only limited information to the Journal log. You can extend polkit log entries related to the PC/SC protocol by adding new rules.

Prerequisites

  • You have installed the pcsc-lite package on your system.
  • The pcscd daemon is running.

Procedure

  1. Create a new file in the /etc/polkit-1/rules.d/ directory:

    # touch /etc/polkit-1/rules.d/00-test.rules
  2. Edit the file in an editor of your choice, for example:

    # vi /etc/polkit-1/rules.d/00-test.rules
  3. Insert the following lines:

    polkit.addRule(function(action, subject) {
      if (action.id == "org.debian.pcsc-lite.access_pcsc" ||
      	action.id == "org.debian.pcsc-lite.access_card") {
    	polkit.log("action=" + action);
    	polkit.log("subject=" + subject);
      }
    });

    Save the file, and exit the editor.

  4. Restart the pcscd and polkit services:

    # systemctl restart pcscd.service pcscd.socket polkit.service

Verification

  1. Make an authorization request for pcscd. For example, open the Firefox web browser or use the pkcs11-tool -L command provided by the opensc package.
  2. Display the extended log entries, for example:

    # journalctl -u polkit --since "1 hour ago"
    polkitd[1224]: <no filename>:4: action=[Action id='org.debian.pcsc-lite.access_pcsc']
    polkitd[1224]: <no filename>:5: subject=[Subject pid=2020481 user=user' groups=user,wheel,mock,wireshark seat=null session=null local=true active=true]

Additional resources

  • polkit(8) and polkitd(8) man pages.

5.4. Additional resources

Chapter 6. Scanning the system for configuration compliance and vulnerabilities

A compliance audit is a process of determining whether a given object follows all the rules specified in a compliance policy. The compliance policy is defined by security professionals who specify the required settings, often in the form of a checklist, that a computing environment should use.

Compliance policies can vary substantially across organizations and even across different systems within the same organization. Differences among these policies are based on the purpose of each system and its importance for the organization. Custom software settings and deployment characteristics also raise a need for custom policy checklists.

6.1. Configuration compliance tools in RHEL

You can perform a fully automated compliance audit in Red Hat Enterprise Linux by using the following configuration compliance tools. These tools are based on the Security Content Automation Protocol (SCAP) standard and are designed for automated tailoring of compliance policies.

SCAP Workbench
The scap-workbench graphical utility is designed to perform configuration and vulnerability scans on a single local or remote system. You can also use it to generate security reports based on these scans and evaluations.
OpenSCAP

The OpenSCAP library, with the accompanying oscap command-line utility, is designed to perform configuration and vulnerability scans on a local system, to validate configuration compliance content, and to generate reports and guides based on these scans and evaluations.

Important

You can experience memory-consumption problems while using OpenSCAP, which can cause stopping the program prematurely and prevent generating any result files. See the OpenSCAP memory-consumption problems Knowledgebase article for details.

SCAP Security Guide (SSG)
The scap-security-guide package provides collections of security policies for Linux systems. The guidance consists of a catalog of practical hardening advice, linked to government requirements where applicable. The project bridges the gap between generalized policy requirements and specific implementation guidelines.
Script Check Engine (SCE)
With SCE, which is an extension to the SCAP protocol, administrators can write their security content by using a scripting language, such as Bash, Python, and Ruby. The SCE extension is provided in the openscap-engine-sce package. The SCE itself is not part of the SCAP standard.

To perform automated compliance audits on multiple systems remotely, you can use the OpenSCAP solution for Red Hat Satellite.

6.2. Vulnerability scanning

6.2.1. Red Hat Security Advisories OVAL feed

Red Hat Enterprise Linux security auditing capabilities are based on the Security Content Automation Protocol (SCAP) standard. SCAP is a multi-purpose framework of specifications that supports automated configuration, vulnerability and patch checking, technical control compliance activities, and security measurement.

SCAP specifications create an ecosystem where the format of security content is well-known and standardized although the implementation of the scanner or policy editor is not mandated. This enables organizations to build their security policy (SCAP content) once, no matter how many security vendors they employ.

The Open Vulnerability Assessment Language (OVAL) is the essential and oldest component of SCAP. Unlike other tools and custom scripts, OVAL describes a required state of resources in a declarative manner. OVAL code is never executed directly but using an OVAL interpreter tool called scanner. The declarative nature of OVAL ensures that the state of the assessed system is not accidentally modified.

Like all other SCAP components, OVAL is based on XML. The SCAP standard defines several document formats. Each of them includes a different kind of information and serves a different purpose.

Red Hat Product Security helps customers evaluate and manage risk by tracking and investigating all security issues affecting Red Hat customers. It provides timely and concise patches and security advisories on the Red Hat Customer Portal. Red Hat creates and supports OVAL patch definitions, providing machine-readable versions of our security advisories.

Because of differences between platforms, versions, and other factors, Red Hat Product Security qualitative severity ratings of vulnerabilities do not directly align with the Common Vulnerability Scoring System (CVSS) baseline ratings provided by third parties. Therefore, we recommend that you use the RHSA OVAL definitions instead of those provided by third parties.

The RHSA OVAL definitions are available individually and as a complete package, and are updated within an hour of a new security advisory being made available on the Red Hat Customer Portal.

Each OVAL patch definition maps one-to-one to a Red Hat Security Advisory (RHSA). Because an RHSA can contain fixes for multiple vulnerabilities, each vulnerability is listed separately by its Common Vulnerabilities and Exposures (CVE) name and has a link to its entry in our public bug database.

The RHSA OVAL definitions are designed to check for vulnerable versions of RPM packages installed on a system. It is possible to extend these definitions to include further checks, for example, to find out if the packages are being used in a vulnerable configuration. These definitions are designed to cover software and updates shipped by Red Hat. Additional definitions are required to detect the patch status of third-party software.

Note

The Red Hat Insights for Red Hat Enterprise Linux compliance service helps IT security and compliance administrators to assess, monitor, and report on the security policy compliance of Red Hat Enterprise Linux systems. You can also create and manage your SCAP security policies entirely within the compliance service UI.

6.2.2. Scanning the system for vulnerabilities

The oscap command-line utility enables you to scan local systems, validate configuration compliance content, and generate reports and guides based on these scans and evaluations. This utility serves as a front end to the OpenSCAP library and groups its functionalities to modules (sub-commands) based on the type of SCAP content it processes.

Prerequisites

  • The openscap-scanner and bzip2 packages are installed.

Procedure

  1. Download the latest RHSA OVAL definitions for your system:

    # wget -O - https://www.redhat.com/security/data/oval/v2/RHEL9/rhel-9.oval.xml.bz2 | bzip2 --decompress > rhel-9.oval.xml
  2. Scan the system for vulnerabilities and save results to the vulnerability.html file:

    # oscap oval eval --report vulnerability.html rhel-9.oval.xml

Verification

  • Check the results in a browser of your choice, for example:

    $ firefox vulnerability.html &

Additional resources

6.2.3. Scanning remote systems for vulnerabilities

You can check remote systems for vulnerabilities with the OpenSCAP scanner by using the oscap-ssh tool over the SSH protocol.

Prerequisites

  • The openscap-utils and bzip2 packages are installed on the system you use for scanning.
  • The openscap-scanner package is installed on the remote systems.
  • The SSH server is running on the remote systems.

Procedure

  1. Download the latest RHSA OVAL definitions for your system:

    # wget -O - https://www.redhat.com/security/data/oval/v2/RHEL9/rhel-9.oval.xml.bz2 | bzip2 --decompress > rhel-9.oval.xml
  2. Scan a remote system for vulnerabilities and save the results to a file:

    # oscap-ssh <username>@<hostname> <port> oval eval --report <scan-report.html> rhel-9.oval.xml

    Replace:

    • <username>@<hostname> with the user name and host name of the remote system.
    • <port> with the port number through which you can access the remote system, for example, 22.
    • <scan-report.html> with the file name where oscap saves the scan results.

6.3. Configuration compliance scanning

6.3.1. Configuration compliance in RHEL

You can use configuration compliance scanning to conform to a baseline defined by a specific organization. For example, if you work with the US government, you might have to align your systems with the Operating System Protection Profile (OSPP), and if you are a payment processor, you might have to align your systems with the Payment Card Industry Data Security Standard (PCI-DSS). You can also perform configuration compliance scanning to harden your system security.

Red Hat recommends you follow the Security Content Automation Protocol (SCAP) content provided in the SCAP Security Guide package because it is in line with Red Hat best practices for affected components.

The SCAP Security Guide package provides content which conforms to the SCAP 1.2 and SCAP 1.3 standards. The openscap scanner utility is compatible with both SCAP 1.2 and SCAP 1.3 content provided in the SCAP Security Guide package.

Important

Performing a configuration compliance scanning does not guarantee the system is compliant.

The SCAP Security Guide suite provides profiles for several platforms in a form of data stream documents. A data stream is a file that contains definitions, benchmarks, profiles, and individual rules. Each rule specifies the applicability and requirements for compliance. RHEL provides several profiles for compliance with security policies. In addition to the industry standard, Red Hat data streams also contain information for remediation of failed rules.

Structure of compliance scanning resources

Data stream
   ├── xccdf
   |      ├── benchmark
   |            ├── profile
   |            |    ├──rule reference
   |            |    └──variable
   |            ├── rule
   |                 ├── human readable data
   |                 ├── oval reference
   ├── oval          ├── ocil reference
   ├── ocil          ├── cpe reference
   └── cpe           └── remediation

A profile is a set of rules based on a security policy, such as OSPP, PCI-DSS, and Health Insurance Portability and Accountability Act (HIPAA). This enables you to audit the system in an automated way for compliance with security standards.

You can modify (tailor) a profile to customize certain rules, for example, password length. For more information about profile tailoring, see Customizing a security profile with SCAP Workbench.

6.3.2. Possible results of an OpenSCAP scan

Depending on the data stream and profile applied to an OpenSCAP scan, as well as various properties of your system, each rule may produce a specific result. These are the possible results with brief explanations of their meanings:

Pass
The scan did not find any conflicts with this rule.
Fail
The scan found a conflict with this rule.
Not checked
OpenSCAP does not perform an automatic evaluation of this rule. Check whether your system conforms to this rule manually.
Not applicable
This rule does not apply to the current configuration.
Not selected
This rule is not part of the profile. OpenSCAP does not evaluate this rule and does not display these rules in the results.
Error
The scan encountered an error. For additional information, you can enter the oscap command with the --verbose DEVEL option. Consider opening a bug report.
Unknown
The scan encountered an unexpected situation. For additional information, you can enter the oscap command with the `--verbose DEVEL option. Consider opening a bug report.

6.3.3. Viewing profiles for configuration compliance

Before you decide to use profiles for scanning or remediation, you can list them and check their detailed descriptions using the oscap info subcommand.

Prerequisites

  • The openscap-scanner and scap-security-guide packages are installed.

Procedure

  1. List all available files with security compliance profiles provided by the SCAP Security Guide project:

    $ ls /usr/share/xml/scap/ssg/content/
    ssg-rhel9-ds.xml
  2. Display detailed information about a selected data stream using the oscap info subcommand. XML files containing data streams are indicated by the -ds string in their names. In the Profiles section, you can find a list of available profiles and their IDs:

    $ oscap info /usr/share/xml/scap/ssg/content/ssg-rhel9-ds.xml
    Profiles:
    …
      Title: Australian Cyber Security Centre (ACSC) Essential Eight
        Id: xccdf_org.ssgproject.content_profile_e8
      Title: Health Insurance Portability and Accountability Act (HIPAA)
        Id: xccdf_org.ssgproject.content_profile_hipaa
      Title: PCI-DSS v3.2.1 Control Baseline for Red Hat Enterprise Linux 9
        Id: xccdf_org.ssgproject.content_profile_pci-dss
    …
  3. Select a profile from the data stream file and display additional details about the selected profile. To do so, use oscap info with the --profile option followed by the last section of the ID displayed in the output of the previous command. For example, the ID of the HIPPA profile is xccdf_org.ssgproject.content_profile_hipaa, and the value for the --profile option is hipaa:

Additional resources

6.3.4. Assessing configuration compliance with a specific baseline

You can determine whether your system or a remote system conforms to a specific baseline, and save the results in a report by using the oscap command-line tool.

Prerequisites

  • The openscap-scanner and scap-security-guide packages are installed.
  • You know the ID of the profile within the baseline with which the system should comply. To find the ID, see the Viewing profiles for configuration compliance section.

Procedure

  1. Scan the local system for compliance with the selected profile and save the scan results to a file:

    $ oscap xccdf eval --report <scan-report.html> --profile <profileID> /usr/share/xml/scap/ssg/content/ssg-rhel9-ds.xml

    Replace:

    • <scan-report.html> with the file name where oscap saves the scan results.
    • <profileID> with the profile ID with which the system should comply, for example, hipaa.
  2. Optional: Scan a remote system for compliance with the selected profile and save the scan results to a file:

    $ oscap-ssh <username>@<hostname> <port> xccdf eval --report <scan-report.html> --profile <profileID> /usr/share/xml/scap/ssg/content/ssg-rhel9-ds.xml

    Replace:

    • <username>@<hostname> with the user name and host name of the remote system.
    • <port> with the port number through which you can access the remote system.
    • <scan-report.html> with the file name where oscap saves the scan results.
    • <profileID> with the profile ID with which the system should comply, for example, hipaa.

Additional resources

  • scap-security-guide(8) man page
  • SCAP Security Guide documentation in the /usr/share/doc/scap-security-guide/ directory
  • /usr/share/doc/scap-security-guide/guides/ssg-rhel9-guide-index.html - [Guide to the Secure Configuration of Red Hat Enterprise Linux 9] installed with the scap-security-guide-doc package
  • OpenSCAP memory consumption problems

6.4. Remediating the system to align with a specific baseline

You can remediate the RHEL system to align with a specific baseline. You can remediate the system to align with any profile provided by the SCAP Security Guide. For the details on listing the available profiles, see the Viewing profiles for configuration compliance section.

Warning

If not used carefully, running the system evaluation with the Remediate option enabled might render the system non-functional. Red Hat does not provide any automated method to revert changes made by security-hardening remediations. Remediations are supported on RHEL systems in the default configuration. If your system has been altered after the installation, running remediation might not make it compliant with the required security profile.

Prerequisites

  • The scap-security-guide package is installed.

Procedure

  1. Remediate the system by using the oscap command with the --remediate option:

    # oscap xccdf eval --profile <profileID> --remediate /usr/share/xml/scap/ssg/content/ssg-rhel9-ds.xml

    Replace <profileID> with the profile ID with which the system should comply, for example, hipaa.

  2. Restart your system.

Verification

  1. Evaluate compliance of the system with the profile, and save the scan results to a file:

    $ oscap xccdf eval --report <scan-report.html> --profile <profileID> /usr/share/xml/scap/ssg/content/ssg-rhel9-ds.xml

    Replace:

    • <scan-report.html> with the file name where oscap saves the scan results.
    • <profileID> with the profile ID with which the system should comply, for example, hipaa.

Additional resources

  • scap-security-guide(8) and oscap(8) man pages

6.5. Remediating the system to align with a specific baseline using an SSG Ansible playbook

You can remediate your system to align with a specific baseline by using an Ansible playbook file from the SCAP Security Guide project. This example uses the Health Insurance Portability and Accountability Act (HIPAA) profile, but you can remediate to align with any other profile provided by the SCAP Security Guide. For the details on listing the available profiles, see the Viewing profiles for configuration compliance section.

Warning

If not used carefully, running the system evaluation with the Remediate option enabled might render the system non-functional. Red Hat does not provide any automated method to revert changes made by security-hardening remediations. Remediations are supported on RHEL systems in the default configuration. If your system has been altered after the installation, running remediation might not make it compliant with the required security profile.

Prerequisites

  • The scap-security-guide package is installed.
  • The ansible-core package is installed. See the Ansible Installation Guide for more information.

Procedure

  1. Remediate your system to align with HIPAA by using Ansible:

    # ansible-playbook -i localhost, -c local /usr/share/scap-security-guide/ansible/rhel9-playbook-hipaa.yml
  2. Restart the system.

Verification

  1. Evaluate the compliance of the system with the HIPAA profile, and save the scan results to a file:

    # oscap xccdf eval --profile hipaa --report <scan-report.html> /usr/share/xml/scap/ssg/content/ssg-rhel9-ds.xml

    Replace <scan-report.html> with the file name where oscap saves the scan results.

Additional resources

6.6. Creating a remediation Ansible playbook to align the system with a specific baseline

You can create an Ansible playbook containing only the remediations that are required to align your system with a specific baseline. This example uses the Health Insurance Portability and Accountability Act (HIPAA) profile. With this procedure, you create a smaller playbook that does not cover already satisfied requirements. By following these steps, you do not modify your system in any way, you only prepare a file for later application.

Note

In RHEL 9, Ansible Engine is replaced by the ansible-core package, which contains only built-in modules. Note that many Ansible remediations use modules from the community and Portable Operating System Interface (POSIX) collections, which are not included in the built-in modules. In this case, you can use Bash remediations as a substitute for Ansible remediations. The Red Hat Connector in RHEL 9.0 includes the necessary Ansible modules to enable the remediation playbooks to function with Ansible Core.

Prerequisites

  • The scap-security-guide package is installed.

Procedure

  1. Scan the system and save the results:

    # oscap xccdf eval --profile hipaa --results <hipaa-results.xml> /usr/share/xml/scap/ssg/content/ssg-rhel9-ds.xml
  2. Find the value of the result ID in the file with the results:

    # oscap info <hipaa-results.xml>
  3. Generate an Ansible playbook based on the file generated in step 1:

    # oscap xccdf generate fix --fix-type ansible --result-id <xccdf_org.open-scap_testresult_xccdf_org.ssgproject.content_profile_hipaa> --output <hipaa-remediations.yml> <hipaa-results.xml>
  4. Review the generated file, which contains the Ansible remediations for rules that failed during the scan performed in step 1. After reviewing this generated file, you can apply it by using the ansible-playbook <hipaa-remediations.yml> command.

Verification

  • In a text editor of your choice, review that the generated <hipaa-remediations.yml> file contains rules that failed in the scan performed in step 1.

Additional resources

6.7. Creating a remediation Bash script for a later application

Use this procedure to create a Bash script containing remediations that align your system with a security profile such as HIPAA. Using the following steps, you do not do any modifications to your system, you only prepare a file for later application.

Prerequisites

  • The scap-security-guide package is installed on your RHEL system.

Procedure

  1. Use the oscap command to scan the system and to save the results to an XML file. In the following example, oscap evaluates the system against the hipaa profile:

    # oscap xccdf eval --profile hipaa --results <hipaa-results.xml> /usr/share/xml/scap/ssg/content/ssg-rhel9-ds.xml
  2. Find the value of the result ID in the file with the results:

    # oscap info <hipaa-results.xml>
  3. Generate a Bash script based on the results file generated in step 1:

    # oscap xccdf generate fix --fix-type bash --result-id <xccdf_org.open-scap_testresult_xccdf_org.ssgproject.content_profile_hipaa> --output <hipaa-remediations.sh> <hipaa-results.xml>
  4. The <hipaa-remediations.sh> file contains remediations for rules that failed during the scan performed in step 1. After reviewing this generated file, you can apply it with the ./<hipaa-remediations.sh> command when you are in the same directory as this file.

Verification

  • In a text editor of your choice, review that the <hipaa-remediations.sh> file contains rules that failed in the scan performed in step 1.

Additional resources

  • scap-security-guide(8), oscap(8), and bash(1) man pages

6.8. Scanning the system with a customized profile using SCAP Workbench

SCAP Workbench, which is contained in the scap-workbench package, is a graphical utility that enables users to perform configuration and vulnerability scans on a single local or a remote system, perform remediation of the system, and generate reports based on scan evaluations. Note that SCAP Workbench has limited functionality compared with the oscap command-line utility. SCAP Workbench processes security content in the form of data stream files.

6.8.1. Using SCAP Workbench to scan and remediate the system

To evaluate your system against the selected security policy, use the following procedure.

Prerequisites

  • The scap-workbench package is installed on your system.

Procedure

  1. To run SCAP Workbench from the GNOME Classic desktop environment, press the Super key to enter the Activities Overview, type scap-workbench, and then press Enter. Alternatively, use:

    $ scap-workbench &
  2. Select a security policy using either of the following options:

    • Load Content button on the starting window
    • Open content from SCAP Security Guide
    • Open Other Content in the File menu, and search the respective XCCDF, SCAP RPM, or data stream file.

      scap workbench start
  3. You can allow automatic correction of the system configuration by selecting the Remediate check box. With this option enabled, SCAP Workbench attempts to change the system configuration in accordance with the security rules applied by the policy. This process should fix the related checks that fail during the system scan.

    Warning

    If not used carefully, running the system evaluation with the Remediate option enabled might render the system non-functional. Red Hat does not provide any automated method to revert changes made by security-hardening remediations. Remediations are supported on RHEL systems in the default configuration. If your system has been altered after the installation, running remediation might not make it compliant with the required security profile.

  4. Scan your system with the selected profile by clicking the Scan button.

    scap workbench results
  5. To store the scan results in form of an XCCDF, ARF, or HTML file, click the Save Results combo box. Choose the HTML Report option to generate the scan report in human-readable format. The XCCDF and ARF (data stream) formats are suitable for further automatic processing. You can repeatedly choose all three options.
  6. To export results-based remediations to a file, use the Generate remediation role pop-up menu.

6.8.2. Customizing a security profile with SCAP Workbench

You can customize a security profile by changing parameters in certain rules (for example, minimum password length), removing rules that you cover in a different way, and selecting additional rules, to implement internal policies. You cannot define new rules by customizing a profile.

The following procedure demonstrates the use of SCAP Workbench for customizing (tailoring) a profile. You can also save the tailored profile for use with the oscap command-line utility.

Prerequisites

  • The scap-workbench package is installed on your system.

Procedure

  1. Run SCAP Workbench, and select the profile to customize by using either Open content from SCAP Security Guide or Open Other Content in the File menu.
  2. To adjust the selected security profile according to your needs, click the Customize button.

    This opens the new Customization window that enables you to modify the currently selected profile without changing the original data stream file. Choose a new profile ID.

    Choosing the ID of your new profile
  3. Find a rule to modify using either the tree structure with rules organized into logical groups or the Search field.
  4. Include or exclude rules using check boxes in the tree structure, or modify values in rules where applicable.

    Customizing a rule in the OSPP profile
  5. Confirm the changes by clicking the OK button.
  6. To store your changes permanently, use one of the following options:

    • Save a customization file separately by using Save Customization Only in the File menu.
    • Save all security content at once by Save All in the File menu.

      If you select the Into a directory option, SCAP Workbench saves both the data stream file and the customization file to the specified location. You can use this as a backup solution.

      By selecting the As RPM option, you can instruct SCAP Workbench to create an RPM package containing the data stream file and the customization file. This is useful for distributing the security content to systems that cannot be scanned remotely, and for delivering the content for further processing.

  7. Because SCAP Workbench does not support results-based remediations for tailored profiles, use the exported remediations with the oscap command-line utility.

6.9. Deploying systems that are compliant with a security profile immediately after an installation

You can use the OpenSCAP suite to deploy RHEL systems that are compliant with a security profile, such as OSPP, PCI-DSS, and HIPAA profile, immediately after the installation process. Using this deployment method, you can apply specific rules that cannot be applied later using remediation scripts, for example, a rule for password strength and partitioning.

6.9.1. Profiles not compatible with Server with GUI

Certain security profiles provided as part of the SCAP Security Guide are not compatible with the extended package set included in the Server with GUI base environment. Therefore, do not select Server with GUI when installing systems compliant with one of the following profiles:

Table 6.1. Profiles not compatible with Server with GUI
Profile nameProfile IDJustificationNotes

[DRAFT] CIS Red Hat Enterprise Linux 9 Benchmark for Level 2 - Server

xccdf_org.ssgproject.content_profile_cis

Packages xorg-x11-server-Xorg, xorg-x11-server-common, xorg-x11-server-utils, and xorg-x11-server-Xwayland are part of the Server with GUI package set, but the policy requires their removal.

 

[DRAFT] CIS Red Hat Enterprise Linux 9 Benchmark for Level 1 - Server

xccdf_org.ssgproject.content_profile_cis_server_l1

Packages xorg-x11-server-Xorg, xorg-x11-server-common, xorg-x11-server-utils, and xorg-x11-server-Xwayland are part of the Server with GUI package set, but the policy requires their removal.

 

DISA STIG for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_stig

Packages xorg-x11-server-Xorg, xorg-x11-server-common, xorg-x11-server-utils, and xorg-x11-server-Xwayland are part of the Server with GUI package set, but the policy requires their removal.

To install a RHEL system as a Server with GUI aligned with DISA STIG, you can use the DISA STIG with GUI profile BZ#1648162

6.9.2. Deploying baseline-compliant RHEL systems using the graphical installation

Use this procedure to deploy a RHEL system that is aligned with a specific baseline. This example uses Protection Profile for General Purpose Operating System (OSPP).

Warning

Certain security profiles provided as part of the SCAP Security Guide are not compatible with the extended package set included in the Server with GUI base environment. For additional details, see Profiles not compatible with a GUI server.

Prerequisites

  • You have booted into the graphical installation program. Note that the OSCAP Anaconda Add-on does not support interactive text-only installation.
  • You have accessed the Installation Summary window.

Procedure

  1. From the Installation Summary window, click Software Selection. The Software Selection window opens.
  2. From the Base Environment pane, select the Server environment. You can select only one base environment.
  3. Click Done to apply the setting and return to the Installation Summary window.
  4. Because OSPP has strict partitioning requirements that must be met, create separate partitions for /boot, /home, /var, /tmp, /var/log, /var/tmp, and /var/log/audit.
  5. Click Security Policy. The Security Policy window opens.
  6. To enable security policies on the system, toggle the Apply security policy switch to ON.
  7. Select Protection Profile for General Purpose Operating Systems from the profile pane.
  8. Click Select Profile to confirm the selection.
  9. Confirm the changes in the Changes that were done or need to be done pane that is displayed at the bottom of the window. Complete any remaining manual changes.
  10. Complete the graphical installation process.

    Note

    The graphical installation program automatically creates a corresponding Kickstart file after a successful installation. You can use the /root/anaconda-ks.cfg file to automatically install OSPP-compliant systems.

Verification

  • To check the current status of the system after installation is complete, reboot the system and start a new scan:

    # oscap xccdf eval --profile ospp --report eval_postinstall_report.html /usr/share/xml/scap/ssg/content/ssg-rhel9-ds.xml

Additional resources

6.9.3. Deploying baseline-compliant RHEL systems using Kickstart

You can deploy RHEL systems that are aligned with a specific baseline. This example uses Protection Profile for General Purpose Operating System (OSPP).

Prerequisites

  • The scap-security-guide package is installed on your RHEL 9 system.

Procedure

  1. Open the /usr/share/scap-security-guide/kickstart/ssg-rhel9-ospp-ks.cfg Kickstart file in an editor of your choice.
  2. Update the partitioning scheme to fit your configuration requirements. For OSPP compliance, the separate partitions for /boot, /home, /var, /tmp, /var/log, /var/tmp, and /var/log/audit must be preserved, and you can only change the size of the partitions.
  3. Start a Kickstart installation as described in Performing an automated installation using Kickstart.
Important

Passwords in Kickstart files are not checked for OSPP requirements.

Verification

  • To check the current status of the system after installation is complete, reboot the system and start a new scan:

    # oscap xccdf eval --profile ospp --report eval_postinstall_report.html /usr/share/xml/scap/ssg/content/ssg-rhel9-ds.xml

6.10. Scanning container and container images for vulnerabilities

Use this procedure to find security vulnerabilities in a container or a container image.

Prerequisites

  • The openscap-utils and bzip2 packages are installed.

Procedure

  1. Download the latest RHSA OVAL definitions for your system:

    # wget -O - https://www.redhat.com/security/data/oval/v2/RHEL9/rhel-9.oval.xml.bz2 | bzip2 --decompress > rhel-9.oval.xml
  2. Get the ID of a container or a container image, for example:

    # podman images
    REPOSITORY                            TAG      IMAGE ID       CREATED       SIZE
    registry.access.redhat.com/ubi9/ubi   latest   096cae65a207   7 weeks ago   239 MB
  3. Scan the container or the container image for vulnerabilities and save results to the vulnerability.html file:

    # oscap-podman 096cae65a207 oval eval --report vulnerability.html rhel-9.oval.xml

    Note that the oscap-podman command requires root privileges, and the ID of a container is the first argument.

Verification

  • Check the results in a browser of your choice, for example:

    $ firefox vulnerability.html &

Additional resources

  • For more information, see the oscap-podman(8) and oscap(8) man pages.

6.11. Assessing security compliance of a container or a container image with a specific baseline

You can assess the compliance of your container or a container image with a specific security baseline, such as Operating System Protection Profile (OSPP), Payment Card Industry Data Security Standard (PCI-DSS), and Health Insurance Portability and Accountability Act (HIPAA).

Prerequisites

  • The openscap-utils and scap-security-guide packages are installed.
  • You have root access to the system.

Procedure

  1. Find the ID of a container or a container image, for example:

    # podman images
    REPOSITORY                            TAG      IMAGE ID       CREATED       SIZE
    registry.access.redhat.com/ubi9/ubi   latest   096cae65a207   7 weeks ago   239 MB
  2. Evaluate the compliance of the container image with a profile and save the scan results into a file:

    # oscap-podman <imageID> xccdf eval --report <scan-report.html> --profile <profileID> /usr/share/xml/scap/ssg/content/ssg-rhel9-ds.xml

    Replace:

    • <imageID> with the ID of your container image
    • <scan-report.html> with the file name where oscap saves the scan results
    • <profileID> with the profile ID with which the system should comply, for example, hipaa, ospp, or pci-dss

Verification

  • Check the results in a browser of your choice, for example:

    $ firefox <scan-report.html> &amp;
Note

The rules marked as notapplicable do not apply to containerized systems. These rules apply only to bare-metal and virtualized systems.

Additional resources

  • oscap-podman(8) and scap-security-guide(8) man pages.
  • /usr/share/doc/scap-security-guide/ directory.

6.12. SCAP Security Guide profiles supported in RHEL 9

Use only the SCAP content provided in the particular minor release of RHEL. This is because components that participate in hardening are sometimes updated with new capabilities. SCAP content changes to reflect these updates, but it is not always backward compatible.

In the following tables, you can find the profiles provided in RHEL 9, together with the version of the policy with which the profile aligns.

Table 6.2. SCAP Security Guide profiles supported in RHEL 9.4
Profile nameProfile IDPolicy version

French National Agency for the Security of Information Systems (ANSSI) BP-028 Enhanced Level

xccdf_org.ssgproject.content_profile_anssi_bp28_enhanced

2.0

French National Agency for the Security of Information Systems (ANSSI) BP-028 High Level

xccdf_org.ssgproject.content_profile_anssi_bp28_high

2.0

French National Agency for the Security of Information Systems (ANSSI) BP-028 Intermediary Level

xccdf_org.ssgproject.content_profile_anssi_bp28_intermediary

2.0

French National Agency for the Security of Information Systems (ANSSI) BP-028 Minimal Level

xccdf_org.ssgproject.content_profile_anssi_bp28_minimal

2.0

CCN Red Hat Enterprise Linux 9 - Advanced

xccdf_org.ssgproject.content_profile_ccn_advanced

2022-10

CCN Red Hat Enterprise Linux 9 - Basic

xccdf_org.ssgproject.content_profile_ccn_basic

2022-10

CCN Red Hat Enterprise Linux 9 - Intermediate

xccdf_org.ssgproject.content_profile_ccn_intermediate

2022-10

CIS Red Hat Enterprise Linux 9 Benchmark for Level 2 - Server

xccdf_org.ssgproject.content_profile_cis

1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 1 - Server

xccdf_org.ssgproject.content_profile_cis_server_l1

1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 1 - Workstation

xccdf_org.ssgproject.content_profile_cis_workstation_l1

1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 2 - Workstation

xccdf_org.ssgproject.content_profile_cis_workstation_l2

1.0.0

[DRAFT] Unclassified Information in Non-federal Information Systems and Organizations (NIST 800-171)

xccdf_org.ssgproject.content_profile_cui

r2

Australian Cyber Security Centre (ACSC) Essential Eight

xccdf_org.ssgproject.content_profile_e8

not versioned

Health Insurance Portability and Accountability Act (HIPAA)

xccdf_org.ssgproject.content_profile_hipaa

not versioned

Australian Cyber Security Centre (ACSC) ISM Official

xccdf_org.ssgproject.content_profile_ism_o

not versioned

Protection Profile for General Purpose Operating Systems

xccdf_org.ssgproject.content_profile_ospp

4.3

PCI-DSS v3.2.1 Control Baseline for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_pci-dss

4.0

The Defense Information Systems Agency Security Technical Implementation Guide (DISA STIG) for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_stig

RHEL 9.4.0:V1R2
RHEL 9.4.1 and later:V1R3

The Defense Information Systems Agency Security Technical Implementation Guide (DISA STIG) with GUI for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_stig_gui

RHEL 9.4.0:V1R2
RHEL 9.4.1 and later:V1R3

CCN Red Hat Enterprise Linux 9 - Basic

xccdf_org.ssgproject.content_profile_ccn_basic

2022-10

CCN Red Hat Enterprise Linux 9 - Intermediate

xccdf_org.ssgproject.content_profile_ccn_intermediate

2022-10

CCN Red Hat Enterprise Linux 9 - Advanced

xccdf_org.ssgproject.content_profile_ccn_advanced

2022-10

Table 6.3. SCAP Security Guide profiles supported in RHEL 9.3
Profile nameProfile IDPolicy version

French National Agency for the Security of Information Systems (ANSSI) BP-028 Enhanced Level

xccdf_org.ssgproject.content_profile_anssi_bp28_enhanced

2.0

French National Agency for the Security of Information Systems (ANSSI) BP-028 High Level

xccdf_org.ssgproject.content_profile_anssi_bp28_high

2.0

French National Agency for the Security of Information Systems (ANSSI) BP-028 Intermediary Level

xccdf_org.ssgproject.content_profile_anssi_bp28_intermediary

2.0

French National Agency for the Security of Information Systems (ANSSI) BP-028 Minimal Level

xccdf_org.ssgproject.content_profile_anssi_bp28_minimal

2.0

CCN Red Hat Enterprise Linux 9 - Advanced

xccdf_org.ssgproject.content_profile_ccn_advanced

2022-10

CCN Red Hat Enterprise Linux 9 - Basic

xccdf_org.ssgproject.content_profile_ccn_basic

2022-10

CCN Red Hat Enterprise Linux 9 - Intermediate

xccdf_org.ssgproject.content_profile_ccn_intermediate

2022-10

CIS Red Hat Enterprise Linux 9 Benchmark for Level 2 - Server

xccdf_org.ssgproject.content_profile_cis

1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 1 - Server

xccdf_org.ssgproject.content_profile_cis_server_l1

1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 1 - Workstation

xccdf_org.ssgproject.content_profile_cis_workstation_l1

1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 2 - Workstation

xccdf_org.ssgproject.content_profile_cis_workstation_l2

1.0.0

[DRAFT] Unclassified Information in Non-federal Information Systems and Organizations (NIST 800-171)

xccdf_org.ssgproject.content_profile_cui

r2

Australian Cyber Security Centre (ACSC) Essential Eight

xccdf_org.ssgproject.content_profile_e8

not versioned

Health Insurance Portability and Accountability Act (HIPAA)

xccdf_org.ssgproject.content_profile_hipaa

not versioned

Australian Cyber Security Centre (ACSC) ISM Official

xccdf_org.ssgproject.content_profile_ism_o

not versioned

Protection Profile for General Purpose Operating Systems

xccdf_org.ssgproject.content_profile_ospp

4.3

PCI-DSS v3.2.1 Control Baseline for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_pci-dss

RHEL 9.3.0 to RHEL 9.3.2:3.2.1
RHEL 9.3.3:4.0

The Defense Information Systems Agency Security Technical Implementation Guide (DISA STIG) for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_stig

RHEL 9.3.0: DRAFT[a]
RHEL 9.3.2:V1R1
RHEL 9.3.3 and later:V1R2

The Defense Information Systems Agency Security Technical Implementation Guide (DISA STIG) with GUI for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_stig_gui

RHEL 9.3.0: DRAFT[a]
RHEL 9.3.2:V1R1
RHEL 9.3.3 and later:V1R2

CCN Red Hat Enterprise Linux 9 - Basic

xccdf_org.ssgproject.content_profile_ccn_basic

2022-10

CCN Red Hat Enterprise Linux 9 - Intermediate

xccdf_org.ssgproject.content_profile_ccn_intermediate

2022-10

CCN Red Hat Enterprise Linux 9 - Advanced

xccdf_org.ssgproject.content_profile_ccn_advanced

2022-10

[a] DISA has not yet published an official benchmark for RHEL 9
Table 6.4. SCAP Security Guide profiles supported in RHEL 9.2
Profile nameProfile IDPolicy version

French National Agency for the Security of Information Systems (ANSSI) BP-028 Enhanced Level

xccdf_org.ssgproject.content_profile_anssi_bp28_enhanced

RHEL 9.2.0 to RHEL 9.2.2:1.2
RHEL 9.2.3 and later:2.0

French National Agency for the Security of Information Systems (ANSSI) BP-028 High Level

xccdf_org.ssgproject.content_profile_anssi_bp28_high

RHEL 9.2.0 to RHEL 9.2.2:1.2
RHEL 9.2.3 and later:2.0

French National Agency for the Security of Information Systems (ANSSI) BP-028 Intermediary Level

xccdf_org.ssgproject.content_profile_anssi_bp28_intermediary

RHEL 9.2.0 to RHEL 9.2.2:1.2
RHEL 9.2.3 and later:2.0

French National Agency for the Security of Information Systems (ANSSI) BP-028 Minimal Level

xccdf_org.ssgproject.content_profile_anssi_bp28_minimal

RHEL 9.2.0 to RHEL 9.2.2:1.2
RHEL 9.2.3 and later:2.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 2 - Server

xccdf_org.ssgproject.content_profile_cis

1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 1 - Server

xccdf_org.ssgproject.content_profile_cis_server_l1

1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 1 - Workstation

xccdf_org.ssgproject.content_profile_cis_workstation_l1

1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 2 - Workstation

xccdf_org.ssgproject.content_profile_cis_workstation_l2

1.0.0

[DRAFT] Unclassified Information in Non-federal Information Systems and Organizations (NIST 800-171)

xccdf_org.ssgproject.content_profile_cui

r2

Australian Cyber Security Centre (ACSC) Essential Eight

xccdf_org.ssgproject.content_profile_e8

not versioned

Health Insurance Portability and Accountability Act (HIPAA)

xccdf_org.ssgproject.content_profile_hipaa

not versioned

Australian Cyber Security Centre (ACSC) ISM Official

xccdf_org.ssgproject.content_profile_ism_o

not versioned

Protection Profile for General Purpose Operating Systems

xccdf_org.ssgproject.content_profile_ospp

4.2.1

PCI-DSS v3.2.1 Control Baseline for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_pci-dss

RHEL 9.2.0 to RHEL 9.2.5:3.2.1
RHEL 9.2.6 and later:4.0

The Defense Information Systems Agency Security Technical Implementation Guide (DISA STIG) for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_stig

RHEL 9.2.0 to RHEL 9.2.4: DRAFT[a]
RHEL 9.2.5:V1R1
RHEL 9.2.6 to RHEL 9.2.8:V1R2
RHEL 9.2.9 and later:V1R3

The Defense Information Systems Agency Security Technical Implementation Guide (DISA STIG) with GUI for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_stig_gui

RHEL 9.2.0 to 9.2.4: DRAFT[a]
RHEL 9.2.5:V1R1
RHEL 9.2.6 to RHEL 9.2.8:V1R2
RHEL 9.2.9 and later:V1R3

CCN Red Hat Enterprise Linux 9 - Basic

xccdf_org.ssgproject.content_profile_ccn_basic

2022-10

CCN Red Hat Enterprise Linux 9 - Intermediate

xccdf_org.ssgproject.content_profile_ccn_intermediate

2022-10

CCN Red Hat Enterprise Linux 9 - Advanced

xccdf_org.ssgproject.content_profile_ccn_advanced

2022-10

Table 6.5. SCAP Security Guide profiles supported in RHEL 9.1
Profile nameProfile IDPolicy version

French National Agency for the Security of Information Systems (ANSSI) BP-028 Enhanced Level

xccdf_org.ssgproject.content_profile_anssi_bp28_enhanced

1.2

French National Agency for the Security of Information Systems (ANSSI) BP-028 High Level

xccdf_org.ssgproject.content_profile_anssi_bp28_high

1.2

French National Agency for the Security of Information Systems (ANSSI) BP-028 Intermediary Level

xccdf_org.ssgproject.content_profile_anssi_bp28_intermediary

1.2

French National Agency for the Security of Information Systems (ANSSI) BP-028 Minimal Level

xccdf_org.ssgproject.content_profile_anssi_bp28_minimal

1.2

CIS Red Hat Enterprise Linux 9 Benchmark for Level 2 - Server

xccdf_org.ssgproject.content_profile_cis

RHEL 9.1.0 and RHEL 9.1.1:DRAFT[a]
RHEL 9.1.2 and later:1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 1 - Server

xccdf_org.ssgproject.content_profile_cis_server_l1

RHEL 9.1.0 and RHEL 9.1.1:DRAFT[a]
RHEL 9.1.2 and later:1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 1 - Workstation

xccdf_org.ssgproject.content_profile_cis_workstation_l1

RHEL 9.1.0 and RHEL 9.1.1:DRAFT[a]
RHEL 9.1.2 and later:1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 2 - Workstation

xccdf_org.ssgproject.content_profile_cis_workstation_l2

RHEL 9.1.0 and RHEL 9.1.1:DRAFT[a]
RHEL 9.1.2 and later:1.0.0

[DRAFT] Unclassified Information in Non-federal Information Systems and Organizations (NIST 800-171)

xccdf_org.ssgproject.content_profile_cui

r2

Australian Cyber Security Centre (ACSC) Essential Eight

xccdf_org.ssgproject.content_profile_e8

not versioned

Health Insurance Portability and Accountability Act (HIPAA)

xccdf_org.ssgproject.content_profile_hipaa

not versioned

Australian Cyber Security Centre (ACSC) ISM Official

xccdf_org.ssgproject.content_profile_ism_o

not versioned

Protection Profile for General Purpose Operating Systems

xccdf_org.ssgproject.content_profile_ospp

4.2.1

PCI-DSS v3.2.1 Control Baseline for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_pci-dss

3.2.1

[DRAFT] The Defense Information Systems Agency Security Technical Implementation Guide (DISA STIG) for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_stig

DRAFT[a]

[DRAFT] The Defense Information Systems Agency Security Technical Implementation Guide (DISA STIG) with GUI for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_stig_gui

DRAFT[a]

[a] CIS has not yet published an official benchmark for RHEL 9
Table 6.6. SCAP Security Guide profiles supported in RHEL 9.0
Profile nameProfile IDPolicy version

French National Agency for the Security of Information Systems (ANSSI) BP-028 Enhanced Level

xccdf_org.ssgproject.content_profile_anssi_bp28_enhanced

RHEL 9.0.0 to RHEL 9.0.10:1.2
RHEL 9.0.11 and later:2.0

French National Agency for the Security of Information Systems (ANSSI) BP-028 High Level

xccdf_org.ssgproject.content_profile_anssi_bp28_high

RHEL 9.0.0 to RHEL 9.0.10:1.2
RHEL 9.0.11 and later:2.0

French National Agency for the Security of Information Systems (ANSSI) BP-028 Intermediary Level

xccdf_org.ssgproject.content_profile_anssi_bp28_intermediary

RHEL 9.0.0 to RHEL 9.0.10:1.2
RHEL 9.0.11 and later:2.0

French National Agency for the Security of Information Systems (ANSSI) BP-028 Minimal Level

xccdf_org.ssgproject.content_profile_anssi_bp28_minimal

RHEL 9.0.0 to RHEL 9.0.10:1.2
RHEL 9.0.11 and later:2.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 2 - Server

xccdf_org.ssgproject.content_profile_cis

RHEL 9.0.0 to RHEL 9.0.6:DRAFT[a]
RHEL 9.0.7 and later:1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 1 - Server

xccdf_org.ssgproject.content_profile_cis_server_l1

RHEL 9.0.0 to RHEL 9.0.6:DRAFT[a]
RHEL 9.0.7 and later:1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 1 - Workstation

xccdf_org.ssgproject.content_profile_cis_workstation_l1

RHEL 9.0.0 to RHEL 9.0.6:DRAFT[a]
RHEL 9.0.7 and later:1.0.0

CIS Red Hat Enterprise Linux 9 Benchmark for Level 2 - Workstation

xccdf_org.ssgproject.content_profile_cis_workstation_l2

RHEL 9.0.0 to RHEL 9.0.6:DRAFT[a]
RHEL 9.0.7 and later:1.0.0

[DRAFT] Unclassified Information in Non-federal Information Systems and Organizations (NIST 800-171)

xccdf_org.ssgproject.content_profile_cui

r2

Australian Cyber Security Centre (ACSC) Essential Eight

xccdf_org.ssgproject.content_profile_e8

not versioned

Health Insurance Portability and Accountability Act (HIPAA)

xccdf_org.ssgproject.content_profile_hipaa

not versioned

Australian Cyber Security Centre (ACSC) ISM Official

xccdf_org.ssgproject.content_profile_ism_o

not versioned

Protection Profile for General Purpose Operating Systems

xccdf_org.ssgproject.content_profile_ospp

RHEL 9.0.0 to RHEL 9.0.2:DRAFT
RHEL 9.0.3 and later:4.2.1

PCI-DSS v3.2.1 Control Baseline for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_pci-dss

RHEL 9.0.0 to RHEL 9.0.14:3.2.1
RHEL 9.0.15:4.0

The Defense Information Systems Agency Security Technical Implementation Guide (DISA STIG) for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_stig

RHEL 9.0.0 to RHEL 9.0.13: DRAFT[a]
RHEL 9.0.14:V1R1
RHEL 9.0.15 to 9.0.17:V1R2
RHEL 9.0.18 and later:V1R3

The Defense Information Systems Agency Security Technical Implementation Guide (DISA STIG) with GUI for Red Hat Enterprise Linux 9

xccdf_org.ssgproject.content_profile_stig_gui

RHEL 9.0.0 to RHEL 9.0.13: DRAFT[a]
RHEL 9.0.14:V1R1
RHEL 9.0.15 to 9.0.17:V1R2
RHEL 9.0.18 and later:V1R3

CCN Red Hat Enterprise Linux 9 - Basic

xccdf_org.ssgproject.content_profile_ccn_basic

RHEL 9.0.11 and later:2022-10

CCN Red Hat Enterprise Linux 9 - Intermediate

xccdf_org.ssgproject.content_profile_ccn_intermediate

RHEL 9.0.11 and later:2022-10

CCN Red Hat Enterprise Linux 9 - Advanced

xccdf_org.ssgproject.content_profile_ccn_advanced

RHEL 9.0.11 and later:2022-10

Chapter 7. Ensuring system integrity with Keylime

With Keylime, you can continuously monitor the integrity of remote systems and verify the state of systems at boot. You can also send encrypted files to the monitored systems, and specify automated actions triggered whenever a monitored system fails the integrity test.

7.1. How Keylime works

You can deploy Keylime agents to perform one or more of the following actions:

Runtime integrity monitoring
Keylime runtime integrity monitoring continuously monitors the system on which the agent is deployed and measures the integrity of the files included in the allowlist and not included in the excludelist.
Measured boot
Keylime measured boot verifies the system state at boot.

Keylime’s concept of trust is based on the Trusted Platform Module (TPM) technology. A TPM is a hardware, firmware, or virtual component with integrated cryptographic keys. By polling TPM quotes and comparing the hashes of objects, Keylime provides initial and runtime monitoring of remote systems.

Important

Keylime running in a virtual machine or using a virtual TPM depends upon the integrity of the underlying host. Ensure you trust the host environment before relying upon Keylime measurements in a virtual environment.

Keylime consists of three main components:

Verifier
Initially and continuously verifies the integrity of the systems that run the agent.
Registrar
Contains a database of all agents and it hosts the public keys of the TPM vendors.
Agent
Deployed to remote systems measured by the verifier.

In addition, Keylime uses the keylime_tenant utility for many functions, including provisioning the agents on the target systems.

Figure 7.1. Connections between Keylime components through configurations

The Keylime components are connected through their configuration options.

Keylime ensures the integrity of the monitored systems in a chain of trust by using keys and certificates exchanged between the components and the tenant. For a secure foundation of this chain, use a certificate authority (CA) that you can trust.

Note

If the agent receives no key and certificate, it generates a key and a self-signed certificate with no involvement from the CA.

Figure 7.2. Connections between Keylime components certificates and keys

The Keylime components are connected through the keys and certificates.

7.2. Configuring Keylime verifier

The verifier is the most important component in Keylime. It performs initial and periodic checks of system integrity and supports bootstrapping a cryptographic key securely with the agent. The verifier uses mutual TLS encryption for its control interface.

Important

To maintain the chain of trust, keep the system that runs the verifier secure and under your control.

You can install the verifier on a separate system or on the same system as the Keylime registrar, depending on your requirements. Running the verifier and registrar on separate systems provides better performance.

Note

To keep the configuration files organized within the drop-in directories, use file names with a two-digit number prefix, for example /etc/keylime/verifier.conf.d/00-verifier-ip.conf. The configuration processing reads the files inside the drop-in directory in lexicographic order and sets each option to the last value it reads.

Prerequisites

  • You have root permissions and network connection to the system or systems on which you want to install Keylime components.
  • You have valid keys and certificates from your certificate authority.
  • Optional: You have access to the databases where Keylime saves data from the verifier. You can use any of the following database management systems:

    • SQLite (default)
    • PostgreSQL
    • MySQL
    • MariaDB

Procedure

  1. Install the Keylime verifier:

    # dnf install keylime-verifier
  2. Define the IP address and port of verifier by creating a new .conf file in the /etc/keylime/verifier.conf.d/ directory, for example, /etc/keylime/verifier.conf.d/00-verifier-ip.conf, with the following content:

    [verifier]
    ip = <verifier_IP_address>
    • Replace <verifier_IP_address> with the verifier’s IP address. Alternatively, use ip = * or ip = 0.0.0.0 to bind the verifier to all available IP addresses.
    • Optionally, you can also change the verifier’s port from the default value 8881 by using the port option.
  3. Optional: Configure the verifier’s database for the list of agents. The default configuration uses an SQLite database in the verifier’s /var/lib/keylime/cv_data.sqlite/ directory. You can define a different database by creating a new .conf file in the /etc/keylime/verifier.conf.d/ directory, for example, /etc/keylime/verifier.conf.d/00-db-url.conf, with the following content:

    [verifier]
    database_url = <protocol>://<name>:<password>@<ip_address_or_hostname>/<properties>

    Replace <protocol>://<name>:<password>@<ip_address_or_hostname>/<properties> with the URL of the database, for example, postgresql://verifier:UQ?nRNY9g7GZzN7@198.51.100.1/verifierdb.

    Ensure that the credentials you use provide the permissions for Keylime to create the database structure.

  4. Add certificates and keys to the verifier. You can either let Keylime generate them, or use existing keys and certificates:

    • With the default tls_dir = generate option, Keylime generates new certificates for the verifier, registrar, and tenant in the /var/lib/keylime/cv_ca/ directory.
    • To load existing keys and certificates in the configuration, define their location in the verifier configuration. The certificates must be accessible by the keylime user, under which the Keylime services are running.

      Create a new .conf file in the /etc/keylime/verifier.conf.d/ directory, for example, /etc/keylime/verifier.conf.d/00-keys-and-certs.conf, with the following content:

      [verifier]
      tls_dir = /var/lib/keylime/cv_ca
      server_key = </path/to/server_key>
      server_key_password = <passphrase1>
      server_cert = </path/to/server_cert>
      trusted_client_ca = ['</path/to/ca/cert1>', '</path/to/ca/cert2>']
      client_key = </path/to/client_key>
      client_key_password = <passphrase2>
      client_cert = </path/to/client_cert>
      trusted_server_ca = ['</path/to/ca/cert3>', '</path/to/ca/cert4>']
      Note

      Use absolute paths to define key and certificate locations. Alternatively, relative paths are resolved from the directory defined in the tls_dir option.

  5. Open the port in firewall:

    # firewall-cmd --add-port 8881/tcp
    # firewall-cmd --runtime-to-permanent

    If you use a different port, replace 8881 with the port number defined in the .conf file.

  6. Start the verifier service:

    # systemctl enable --now keylime_verifier
    Note

    In the default configuration, start the keylime_verifier before starting the keylime_registrar service because the verifier creates the CA and certificates for the other Keylime components. This order is not necessary when you use custom certificates.

Verification

  • Check that the keylime_verifier service is active and running:

    # systemctl status keylime_verifier
    ● keylime_verifier.service - The Keylime verifier
         Loaded: loaded (/usr/lib/systemd/system/keylime_verifier.service; disabled; vendor preset: disabled)
         Active: active (running) since Wed 2022-11-09 10:10:08 EST; 1min 45s ago

7.3. Configuring Keylime verifier as a container

The Keylime verifier performs initial and periodic checks of system integrity and supports bootstrapping a cryptographic key securely with the agent. You can configure the Keylime verifier as a container instead of the RPM method, without any binaries or packages on the host. The container deployment provides better isolation, modularity, and reproducibility of Keylime components.

After you start the container, the Keylime verifier is deployed with default configuration files. You can customize the configuration by using one or more of following methods:

  • Mounting the host’s directories that contain the configuration files to the container. This is available in all versions of RHEL 9.
  • Modifying the environment variables directly on the container. This is available in RHEL 9.3 and later versions. Modifying the environment variables overrides the values from the configuration files.

Prerequisites

  • The podman package and its dependencies are installed on the system.
  • Optional: You have access to a database where Keylime saves data from the verifier. You can use any of the following database management systems:

    • SQLite (default)
    • PostgreSQL
    • MySQL
    • MariaDB
  • You have valid keys and certificates from your certificate authority.

Procedure

  1. Optional: Install the keylime-verifier package to access the configuration files. You can configure the container without this package, but it might be easier to modify the configuration files provided with the package.

    # dnf install keylime-verifier
  2. Bind the verifier to all available IP addresses by creating a new .conf file in the /etc/keylime/verifier.conf.d/ directory, for example, /etc/keylime/verifier.conf.d/00-verifier-ip.conf, with the following content:

    [verifier]
    ip = *
    • Optionally, you can also change the verifier’s port from the default value 8881 by using the port option.
  3. Optional: Configure the verifier’s database for the list of agents. The default configuration uses an SQLite database in the verifier’s /var/lib/keylime/cv_data.sqlite/ directory. You can define a different database by creating a new .conf file in the /etc/keylime/verifier.conf.d/ directory, for example, /etc/keylime/verifier.conf.d/00-db-url.conf, with the following content:

    [verifier]
    database_url = <protocol>://<name>:<password>@<ip_address_or_hostname>/<properties>

    Replace <protocol>://<name>:<password>@<ip_address_or_hostname>/<properties> with the URL of the database, for example, postgresql://verifier:UQ?nRNY9g7GZzN7@198.51.100.1/verifierdb.

    Ensure that the credentials you use have the permissions for Keylime to create the database structure.

  4. Add certificates and keys to the verifier. You can either let Keylime generate them, or use existing keys and certificates:

    • With the default tls_dir = generate option, Keylime generates new certificates for the verifier, registrar, and tenant in the /var/lib/keylime/cv_ca/ directory.
    • To load existing keys and certificates in the configuration, define their location in the verifier configuration. The certificates must be accessible by the keylime user, under which the Keylime processes are running.

      Create a new .conf file in the /etc/keylime/verifier.conf.d/ directory, for example, /etc/keylime/verifier.conf.d/00-keys-and-certs.conf, with the following content:

      [verifier]
      tls_dir = /var/lib/keylime/cv_ca
      server_key = </path/to/server_key>
      server_cert = </path/to/server_cert>
      trusted_client_ca = ['</path/to/ca/cert1>', '</path/to/ca/cert2>']
      client_key = </path/to/client_key>
      client_cert = </path/to/client_cert>
      trusted_server_ca = ['</path/to/ca/cert3>', '</path/to/ca/cert4>']
      Note

      Use absolute paths to define key and certificate locations. Alternatively, relative paths are resolved from the directory defined in the tls_dir option.

  5. Open the port in firewall:

    # firewall-cmd --add-port 8881/tcp
    # firewall-cmd --runtime-to-permanent

    If you use a different port, replace 8881 with the port number defined in the .conf file.

  6. Run the container:

    $ podman run --name keylime-verifier \
      -p 8881:8881 \
      -v /etc/keylime/verifier.conf.d:/etc/keylime/verifier.conf.d:Z \
      -v /var/lib/keylime/cv_ca:/var/lib/keylime/cv_ca:Z \
      -d \
      -e KEYLIME_VERIFIER_SERVER_KEY_PASSWORD=<passphrase1> \
      -e KEYLIME_VERIFIER_CLIENT_KEY_PASSWORD=<passphrase2> \
      registry.access.redhat.com/rhel9/keylime-verifier
    • The -p option opens the default port 8881 on the host and on the container.
    • The -v option creates a bind mount for the directory to the container.

      • With the Z option, Podman marks the content with a private unshared label. This means only the current container can use the private volume.
    • The -d option runs the container detached and in the background.
    • The option -e KEYLIME_VERIFIER_SERVER_KEY_PASSWORD=<passphrase1> defines the server key passphrase.
    • The option -e KEYLIME_VERIFIER_CLIENT_KEY_PASSWORD=<passphrase2> defines the client key passphrase.
    • You can override configuration options with environment variables by using the option -e KEYLIME_VERIFIER_<ENVIRONMENT_VARIABLE>=<value>. To modify additional options, insert the -e option separately for each environment variable. For a complete list of environment variables and their default values, see Keylime environment variables.

Verification

  • Check that the container is running:

    $ podman ps -a
    CONTAINER ID  IMAGE                                                     COMMAND           CREATED         STATUS         PORTS                   NAMES
    80b6b9dbf57c  registry.access.redhat.com/rhel9/keylime-verifier:latest  keylime_verifier  14 seconds ago  Up 14 seconds  0.0.0.0:8881->8881/tcp  keylime-verifier

Additional resources

  • For more information about Keylime components, see How Keylime works.
  • For more information about configuring the Keylime verifier, see Configuring Keylime verifier.
  • For more information about the podman run command, see the podman-run(1) man page.

7.4. Configuring Keylime registrar

The registrar is the Keylime component that contains a database of all agents, and it hosts the public keys of the TPM vendors. After the registrar’s HTTPS service accepts trusted platform module (TPM) public keys, it presents an interface to obtain these public keys for checking quotes.

Important

To maintain the chain of trust, keep the system that runs the registrar secure and under your control.

You can install the registrar on a separate system or on the same system as the Keylime verifier, depending on your requirements. Running the verifier and registrar on separate systems provides better performance.

Note

To keep the configuration files organized within the drop-in directories, use file names with a two-digit number prefix, for example /etc/keylime/registrar.conf.d/00-registrar-ip.conf. The configuration processing reads the files inside the drop-in directory in lexicographic order and sets each option to the last value it reads.

Prerequisites

  • You have network access to the systems where the Keylime verifier is installed and running. For more information, see Section 7.2, “Configuring Keylime verifier”.
  • You have root permissions and network connection to the system or systems on which you want to install Keylime components.
  • You have access to the database where Keylime saves data from the registrar. You can use any of the following database management systems:

    • SQLite (default)
    • PostgreSQL
    • MySQL
    • MariaDB
  • You have valid keys and certificates from your certificate authority.

Procedure

  1. Install the Keylime registrar:

    # dnf install keylime-registrar
  2. Define the IP address and port of the registrar by creating a new .conf file in the /etc/keylime/registrar.conf.d/ directory, for example, /etc/keylime/registrar.conf.d/00-registrar-ip.conf, with the following content:

    [registrar]
    ip = <registrar_IP_address>
    • Replace <registrar_IP_address> with the registrar’s IP address. Alternatively, use ip = * or ip = 0.0.0.0 to bind the registrar to all available IP addresses.
    • Optionally, change the port to which the Keylime agents connect by using the port option. The default value is 8890.
    • Optionally, change the TLS port to which the Keylime verifier and tenant connect by using the tls_port option. The default value is 8891.
  3. Optional: Configure the registrar’s database for the list of agents. The default configuration uses an SQLite database in the registrar’s /var/lib/keylime/reg_data.sqlite directory. You can create a new .conf file in the /etc/keylime/registrar.conf.d/ directory, for example, /etc/keylime/registrar.conf.d/00-db-url.conf, with the following content:

    [registrar]
    database_url = <protocol>://<name>:<password>@<ip_address_or_hostname>/<properties>

    Replace <protocol>://<name>:<password>@<ip_address_or_hostname>/<properties> with the URL of the database, for example, postgresql://registrar:EKYYX-bqY2?#raXm@198.51.100.1/registrardb.

    Ensure that the credentials you use have the permissions for Keylime to create the database structure.

  4. Add certificates and keys to the registrar:

    • You can use the default configuration and load the keys and certificates to the /var/lib/keylime/reg_ca/ directory.
    • Alternatively, you can define the location of the keys and certificates in the configuration. Create a new .conf file in the /etc/keylime/registrar.conf.d/ directory, for example, /etc/keylime/registrar.conf.d/00-keys-and-certs.conf, with the following content:

      [registrar]
      tls_dir = /var/lib/keylime/reg_ca
      server_key = </path/to/server_key>
      server_key_password = <passphrase1>
      server_cert = </path/to/server_cert>
      trusted_client_ca = ['</path/to/ca/cert1>', '</path/to/ca/cert2>']
      Note

      Use absolute paths to define key and certificate locations. Alternatively, you can define a directory in the tls_dir option and use paths relative to that directory.

  5. Open the ports in firewall:

    # firewall-cmd --add-port 8890/tcp --add-port 8891/tcp
    # firewall-cmd --runtime-to-permanent

    If you use a different port, replace 8890 or 8891 with the port number defined in the .conf file.

  6. Start the keylime_registrar service:

    # systemctl enable --now keylime_registrar
    Note

    In the default configuration, start the keylime_verifier before starting the keylime_registrar service because the verifier creates the CA and certificates for the other Keylime components. This order is not necessary when you use custom certificates.

Verification

  • Check that the keylime_registrar service is active and running:

    # systemctl status keylime_registrar
    ● keylime_registrar.service - The Keylime registrar service
         Loaded: loaded (/usr/lib/systemd/system/keylime_registrar.service; disabled; vendor preset: disabled)
         Active: active (running) since Wed 2022-11-09 10:10:17 EST; 1min 42s ago
    ...

7.5. Configuring Keylime registrar as a container

The registrar is the Keylime component that contains a database of all agents, and it hosts the public keys of the trusted platform module (TPM) vendors. After the registrar’s HTTPS service accepts TPM public keys, it presents an interface to obtain these public keys for checking quotes. You can configure the Keylime registrar as a container instead of the RPM method, without any binaries or packages on the host. The container deployment provides better isolation, modularity, and reproducibility of Keylime components.

After you start the container, the Keylime registrar is deployed with default configuration files. You can customize the configuration by using one or more of following methods:

  • Mounting the host’s directories that contain the configuration files to the container. This is available in all versions of RHEL 9.
  • Modifying the environment variables directly on the container. This is available in RHEL 9.3 and later versions. Modifying the environment variables overrides the values from the configuration files.

Prerequisites

  • The podman package and its dependencies are installed on the system.
  • Optional: You have access to a database where Keylime saves data from the registrar. You can use any of the following database management systems:

    • SQLite (default)
    • PostgreSQL
    • MySQL
    • MariaDB
  • You have valid keys and certificates from your certificate authority.

Procedure

  1. Optional: Install the keylime-registrar package to access the configuration files. You can configure the container without this package, but it might be easier to modify the configuration files provided with the package.

    # dnf install keylime-registrar
  2. Bind the registrar to all available IP addresses by creating a new .conf file in the /etc/keylime/registrar.conf.d/ directory, for example, /etc/keylime/registrar.conf.d/00-registrar-ip.conf, with the following content:

    [registrar]
    ip = *
    • Optionally, change the port to which the Keylime agents connect by using the port option. The default value is 8890.
    • Optionally, change the TLS port to which the Keylime tenant connects by using the tls_port option. The default value is 8891.
  3. Optional: Configure the registrar’s database for the list of agents. The default configuration uses an SQLite database in the registrar’s /var/lib/keylime/reg_data.sqlite directory. You can create a new .conf file in the /etc/keylime/registrar.conf.d/ directory, for example, /etc/keylime/registrar.conf.d/00-db-url.conf, with the following content:

    [registrar]
    database_url = &lt;protocol&gt;://&lt;name&gt;:&lt;password&gt;@&lt;ip_address_or_hostname&gt;/&lt;properties&gt;

    Replace <protocol>://<name>:<password>@<ip_address_or_hostname>/<properties> with the URL of the database, for example, postgresql://registrar:EKYYX-bqY2?#raXm@198.51.100.1/registrardb.

    Ensure that the credentials you use have the permissions for Keylime to create the database structure.

  4. Add certificates and keys to the registrar:

    • You can use the default configuration and load the keys and certificates to the /var/lib/keylime/reg_ca/ directory.
    • Alternatively, you can define the location of the keys and certificates in the configuration. Create a new .conf file in the /etc/keylime/registrar.conf.d/ directory, for example, /etc/keylime/registrar.conf.d/00-keys-and-certs.conf, with the following content:

      [registrar]
      tls_dir = /var/lib/keylime/reg_ca
      server_key = &lt;/path/to/server_key&gt;
      server_cert = &lt;/path/to/server_cert&gt;
      trusted_client_ca = ['&lt;/path/to/ca/cert1&gt;', '&lt;/path/to/ca/cert2&gt;']
      Note

      Use absolute paths to define key and certificate locations. Alternatively, you can define a directory in the tls_dir option and use paths relative to that directory.

  5. Open the ports in firewall:

    # firewall-cmd --add-port 8890/tcp --add-port 8891/tcp
    # firewall-cmd --runtime-to-permanent

    If you use a different port, replace 8890 or 8891 with the port number defined in the .conf file.

  6. Run the container:

    $ podman run --name keylime-registrar \
      -p 8890:8890 \
      -p 8891:8891 \
      -v /etc/keylime/registrar.conf.d:/etc/keylime/registrar.conf.d:Z \
      -v /var/lib/keylime/reg_ca:/var/lib/keylime/reg_ca:Z \
      -d \
      -e KEYLIME_REGISTRAR_SERVER_KEY_PASSWORD=&lt;passphrase1&gt; \
      registry.access.redhat.com/rhel9/keylime-registrar
    • The -p option opens the default ports 8890 and 8881 on the host and on the container.
    • The -v option creates a bind mount for the directory to the container.

      • With the Z option, Podman marks the content with a private unshared label. This means only the current container can use the private volume.
    • The -d option runs the container detached and in the background.
    • The option -e KEYLIME_VERIFIER_SERVER_KEY_PASSWORD=<passphrase1> defines the server key passphrase.
    • You can override configuration options with environment variables by using the option -e KEYLIME_REGISTRAR_<ENVIRONMENT_VARIABLE>=<value>. To modify additional options, insert the -e option separately for each environment variable. For a complete list of environment variables and their default values, see Section 7.12, “Keylime environment variables”.

Verification

  • Check that the container is running:

    $ podman ps -a
    CONTAINER ID  IMAGE                               COMMAND            CREATED             STATUS             PORTS                                           NAMES
    07d4b4bff1b6  localhost/keylime-registrar:latest  keylime_registrar  12 seconds ago      Up 12 seconds      0.0.0.0:8881->8881/tcp, 0.0.0.0:8891->8891/tcp  keylime-registrar

Additional resources

7.6. Setting up a Keylime server by using RHEL system roles

You can set up the verifier and registrar, which are the Keylime server components, by using the keylime_server RHEL system role. The keylime_server role installs and configures both the verifier and registrar components together on each node.

Perform this procedure on the Ansible control node.

For more information about Keylime, see 8.1. How Keylime works.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.

Procedure

  1. Create a playbook that defines the required role:

    1. Create a new YAML file and open it in a text editor, for example:

      # vi keylime-playbook.yml
    2. Insert the following content:

      ---
      - name: Manage keylime servers
        hosts: all
        vars:
          keylime_server_verifier_ip: "{{ ansible_host }}"
          keylime_server_registrar_ip: "{{ ansible_host }}"
          keylime_server_verifier_tls_dir: <ver_tls_directory>
          keylime_server_verifier_server_cert: <ver_server_certfile>
          keylime_server_verifier_server_key: <ver_server_key>
          keylime_server_verifier_server_key_passphrase: <ver_server_key_passphrase>
          keylime_server_verifier_trusted_client_ca: <ver_trusted_client_ca_list>
          keylime_server_verifier_client_cert: <ver_client_certfile>
          keylime_server_verifier_client_key: <ver_client_key>
          keylime_server_verifier_client_key_passphrase: <ver_client_key_passphrase>
          keylime_server_verifier_trusted_server_ca: <ver_trusted_server_ca_list>
          keylime_server_registrar_tls_dir: <reg_tls_directory>
          keylime_server_registrar_server_cert: <reg_server_certfile>
          keylime_server_registrar_server_key: <reg_server_key>
          keylime_server_registrar_server_key_passphrase: <reg_server_key_passphrase>
          keylime_server_registrar_trusted_client_ca: <reg_trusted_client_ca_list>
        roles:
          - rhel-system-roles.keylime_server

      You can find out more about the variables in Variables for the keylime_server RHEL system role.

  2. Run the playbook:

    $ ansible-playbook <keylime-playbook.yml>

Verification

  1. Check that the keylime_verifier service is active and running on the managed host:

    # systemctl status keylime_verifier
    ● keylime_verifier.service - The Keylime verifier
         Loaded: loaded (/usr/lib/systemd/system/keylime_verifier.service; disabled; vendor preset: disabled)
         Active: active (running) since Wed 2022-11-09 10:10:08 EST; 1min 45s ago
  2. Check that the keylime_registrar service is active and running:

    # systemctl status keylime_registrar
    ● keylime_registrar.service - The Keylime registrar service
         Loaded: loaded (/usr/lib/systemd/system/keylime_registrar.service; disabled; vendor preset: disabled)
         Active: active (running) since Wed 2022-11-09 10:10:17 EST; 1min 42s ago
    ...

7.7. Variables for the keylime_server RHEL system role

When setting up a Keylime server by using the keylime_server RHEL system role, you can customize the following variables for registrar and verifier.

List of keylime_server RHEL system role variables for configuring the Keylime verifier

keylime_server_verifier_ip
Defines the IP address of the verifier.
keylime_server_verifier_tls_dir
Specifies the directory where the keys and certificates are stored. If set to default, the verifier uses the /var/lib/keylime/cv_ca directory.
keylime_server_verifier_server_key_passphrase
Specifies a passphrase to decrypt the server private key. If the value is empty, the private key is not encrypted.

keylime_server_verifier_server_cert: Specifies the Keylime verifier server certificate file.

keylime_server_verifier_trusted_client_ca
Defines the list of trusted client CA certificates. You must store the files in the directory set in the keylime_server_verifier_tls_dir option.
keylime_server_verifier_client_key
Defines the file containing the Keylime verifier private client key.
keylime_server_verifier_client_key_passphrase
Defines the passphrase to decrypt the client private key file. If the value is empty, the private key is not encrypted.
keylime_server_verifier_client_cert
Defines the Keylime verifier client certificate file.
keylime_server_verifier_trusted_server_ca
Defines the list of trusted server CA certificates. You must store the files in the directory set in the keylime_server_verifier_tls_dir option.

List of registrar variables for setting up keylime_server RHEL system role

keylime_server_registrar_ip
Defines the IP address of the registrar.
keylime_server_registrar_tls_dir
Specifies the directory where you store the keys and certificates for the registrar. If you set it to default, the registrar uses the /var/lib/keylime/reg_ca directory.
keylime_server_registrar_server_key
Defines the Keylime registrar private server key file.
keylime_server_registrar_server_key_passphrase
Specifies the passphrase to decrypt the server private key of the registrar. If the value is empty, the private key is not encrypted.
keylime_server_registrar_server_cert
Specifies the Keylime registrar server certificate file.
keylime_server_registrar_trusted_client_ca
Defines the list of trusted client CA certificates. You must store the files in the directory set in the keylime_server_registrar_tls_dir option.

7.8. Configuring Keylime tenant

Keylime uses the keylime_tenant utility for many functions, including provisioning the agents on the target systems. You can install keylime_tenant on any system, including the systems that run other Keylime components, or on a separate system, depending on your requirements.

Prerequisites

Procedure

  1. Install the Keylime tenant:

    # dnf install keylime-tenant
  2. Define the tenant’s connection to the Keylime verifier by editing the /etc/keylime/tenant.conf.d/00-verifier-ip.conf file:

    [tenant]
    verifier_ip = <verifier_ip>
    • Replace <verifier_ip> with the IP address to the verifier’s system.
    • If the verifier uses a different port than the default value 8881, add the verifier_port = <verifier_port> setting.
  3. Define the tenant’s connection to the Keylime registrar by editing the /etc/keylime/tenant.conf.d/00-registrar-ip.conf file:

    [tenant]
    registrar_ip = <registrar_ip>
    • Replace <registrar_ip> with the IP address to the registrar’s system.
    • If the registrar uses a different port than the default value 8891, add the registrar_port = <registrar_port> setting.
  4. Add certificates and keys to the tenant:

    1. You can use the default configuration and load the keys and certificates to the /var/lib/keylime/cv_ca directory.
    2. Alternatively, you can define the location of the keys and certificates in the configuration. Create a new .conf file in the /etc/keylime/tenant.conf.d/ directory, for example, /etc/keylime/tenant.conf.d/00-keys-and-certs.conf, with the following content:

      [tenant]
      tls_dir = /var/lib/keylime/cv_ca
      client_key = tenant-key.pem
      client_key_password = <passphrase1>
      client_cert = tenant-cert.pem
      trusted_server_ca = ['</path/to/ca/cert>']

      The trusted_server_ca parameter accepts paths to the verifier and registrar server CA certificate. You can provide multiple comma-separated paths, for example if the verifier and registrar use different CAs.

      Note

      Use absolute paths to define key and certificate locations. Alternatively, you can define a directory in the tls_dir option and use paths relative to that directory.

  5. Optional: If the trusted platform module (TPM) endorsement key (EK) cannot be verified by using certificates in the /var/lib/keylime/tpm_cert_store directory, add the certificate to that directory. This can occur particularly when using virtual machines with emulated TPMs.

Verification

  1. Check the status of the verifier:

    # keylime_tenant -c cvstatus
    Reading configuration from ['/etc/keylime/logging.conf']
    2022-10-14 12:56:08.155 - keylime.tpm - INFO - TPM2-TOOLS Version: 5.2
    Reading configuration from ['/etc/keylime/tenant.conf']
    2022-10-14 12:56:08.157 - keylime.tenant - INFO - Setting up client TLS...
    2022-10-14 12:56:08.158 - keylime.tenant - INFO - Using default client_cert option for tenant
    2022-10-14 12:56:08.158 - keylime.tenant - INFO - Using default client_key option for tenant
    2022-10-14 12:56:08.178 - keylime.tenant - INFO - TLS is enabled.
    2022-10-14 12:56:08.178 - keylime.tenant - WARNING - Using default UUID d432fbb3-d2f1-4a97-9ef7-75bd81c00000
    2022-10-14 12:56:08.221 - keylime.tenant - INFO - Verifier at 127.0.0.1 with Port 8881 does not have agent d432fbb3-d2f1-4a97-9ef7-75bd81c00000.

    If correctly set up, and if no agent is configured, the verifier responds that it does not recognize the default agent UUID.

  2. Check the status of the registrar:

    # keylime_tenant -c regstatus
    Reading configuration from ['/etc/keylime/logging.conf']
    2022-10-14 12:56:02.114 - keylime.tpm - INFO - TPM2-TOOLS Version: 5.2
    Reading configuration from ['/etc/keylime/tenant.conf']
    2022-10-14 12:56:02.116 - keylime.tenant - INFO - Setting up client TLS...
    2022-10-14 12:56:02.116 - keylime.tenant - INFO - Using default client_cert option for tenant
    2022-10-14 12:56:02.116 - keylime.tenant - INFO - Using default client_key option for tenant
    2022-10-14 12:56:02.137 - keylime.tenant - INFO - TLS is enabled.
    2022-10-14 12:56:02.137 - keylime.tenant - WARNING - Using default UUID d432fbb3-d2f1-4a97-9ef7-75bd81c00000
    2022-10-14 12:56:02.171 - keylime.registrar_client - CRITICAL - Error: could not get agent d432fbb3-d2f1-4a97-9ef7-75bd81c00000 data from Registrar Server: 404
    2022-10-14 12:56:02.172 - keylime.registrar_client - CRITICAL - Response code 404: agent d432fbb3-d2f1-4a97-9ef7-75bd81c00000 not found
    2022-10-14 12:56:02.172 - keylime.tenant - INFO - Agent d432fbb3-d2f1-4a97-9ef7-75bd81c00000 does not exist on the registrar. Please register the agent with the registrar.
    2022-10-14 12:56:02.172 - keylime.tenant - INFO - {"code": 404, "status": "Agent d432fbb3-d2f1-4a97-9ef7-75bd81c00000 does not exist on registrar 127.0.0.1 port 8891.", "results": {}}

    If correctly set up, and if no agent is configured, the registrar responds that it does not recognize the default agent UUID.

Additional resources

  • For additional advanced options for the keylime_tenant utility, enter the keylime_tenant -h command.

7.9. Configuring Keylime agent

The Keylime agent is the component deployed to all systems to be monitored by Keylime.

By default, the Keylime agent stores all its data in the /var/lib/keylime/ directory of the monitored system.

Note

To keep the configuration files organized within the drop-in directories, use file names with a two-digit number prefix, for example /etc/keylime/agent.conf.d/00-registrar-ip.conf. The configuration processing reads the files inside the drop-in directory in lexicographic order and sets each option to the last value it reads.

Prerequisites

Procedure

  1. Install the Keylime agent:

    # dnf install keylime-agent

    This command installs the keylime-agent-rust package.

  2. Define the agent’s IP address and port in the configuration files. Create a new .conf file in the /etc/keylime/agent.conf.d/ directory, for example, /etc/keylime/agent.conf.d/00-agent-ip.conf, with the following content:

    [agent]
    ip = '<agent_ip>'
    Note

    The Keylime agent configuration uses the TOML format, which is different from the INI format used for configuration of the other components. Therefore, enter values in valid TOML syntax, for example, paths in single quotation marks and arrays of multiple paths in square brackets.

    • Replace <agent_IP_address> with the agent’s IP address. Alternatively, use ip = '*' or ip = '0.0.0.0' to bind the agent to all available IP addresses.
    • Optionally, you can also change the agent’s port from the default value 9002 by using the port = '<agent_port>' option.
  3. Define the registrar’s IP address and port in the configuration files. Create a new .conf file in the /etc/keylime/agent.conf.d/ directory, for example, /etc/keylime/agent.conf.d/00-registrar-ip.conf, with the following content:

    [agent]
    registrar_ip = '<registrar_IP_address>'
    • Replace <registrar_IP_address> with the registrar’s IP address.
    • Optionally, you can also change the registrar’s port from the default value 8890 by using the registrar_port = '<registrar_port>' option.
  4. Optional: Define the agent’s universally unique identifier (UUID). If it is not defined, the default UUID is used. Create a new .conf file in the /etc/keylime/agent.conf.d/ directory, for example, /etc/keylime/agent.conf.d/00-agent-uuid.conf, with the following content:

    [agent]
    uuid = '<agent_UUID>'
    • Replace <agent_UUID> with the agent’s UUID, for example d432fbb3-d2f1-4a97-9ef7-abcdef012345. You can use the uuidgen utility to generate a UUID.
  5. Optional: Load existing keys and certificates for the agent. If the agent receives no server_key and server_cert, it generates its own key and a self-signed certificate.

    Define the location of the keys and certificates in the configuration. Create a new .conf file in the /etc/keylime/agent.conf.d/ directory, for example, /etc/keylime/agent.conf.d/00-keys-and-certs.conf, with the following content:

    [agent]
    server_key = '</path/to/server_key>'
    server_key_password = '<passphrase1>'
    server_cert = '</path/to/server_cert>'
    trusted_client_ca = '[</path/to/ca/cert3>, </path/to/ca/cert4>]'
    Note

    Use absolute paths to define key and certificate locations. The Keylime agent does not accept relative paths.

  6. Open the port in firewall:

    # firewall-cmd --add-port 9002/tcp
    # firewall-cmd --runtime-to-permanent

    If you use a different port, replace 9002 with the port number defined in the .conf file.

  7. Enable and start the keylime_agent service:

    # systemctl enable --now keylime_agent
  8. Optional: From the system where the Keylime tenant is configured, verify that the agent is correctly configured and can connect to the registrar.

    # keylime_tenant -c regstatus --uuid <agent_uuid>
    Reading configuration from ['/etc/keylime/logging.conf']
    ...
    ==\n-----END CERTIFICATE-----\n", "ip": "127.0.0.1", "port": 9002, "regcount": 1, "operational_state": "Registered"}}}
    • Replace <agent_uuid> with the agent’s UUID.

      If the registrar and agent are correctly configured, the output displays the agent’s IP address and port, followed by "operational_state": "Registered".

  9. Create a new IMA policy by entering the following content into the /etc/ima/ima-policy file:

    # PROC_SUPER_MAGIC = 0x9fa0
    dont_measure fsmagic=0x9fa0
    # SYSFS_MAGIC = 0x62656572
    dont_measure fsmagic=0x62656572
    # DEBUGFS_MAGIC = 0x64626720
    dont_measure fsmagic=0x64626720
    # TMPFS_MAGIC = 0x01021994
    dont_measure fsmagic=0x1021994
    # RAMFS_MAGIC
    dont_measure fsmagic=0x858458f6
    # DEVPTS_SUPER_MAGIC=0x1cd1
    dont_measure fsmagic=0x1cd1
    # BINFMTFS_MAGIC=0x42494e4d
    dont_measure fsmagic=0x42494e4d
    # SECURITYFS_MAGIC=0x73636673
    dont_measure fsmagic=0x73636673
    # SELINUX_MAGIC=0xf97cff8c
    dont_measure fsmagic=0xf97cff8c
    # SMACK_MAGIC=0x43415d53
    dont_measure fsmagic=0x43415d53
    # NSFS_MAGIC=0x6e736673
    dont_measure fsmagic=0x6e736673
    # EFIVARFS_MAGIC
    dont_measure fsmagic=0xde5e81e4
    # CGROUP_SUPER_MAGIC=0x27e0eb
    dont_measure fsmagic=0x27e0eb
    # CGROUP2_SUPER_MAGIC=0x63677270
    dont_measure fsmagic=0x63677270
    # OVERLAYFS_MAGIC
    # when containers are used we almost always want to ignore them
    dont_measure fsmagic=0x794c7630
    # MEASUREMENTS
    measure func=BPRM_CHECK
    measure func=FILE_MMAP mask=MAY_EXEC
    measure func=MODULE_CHECK uid=0

    This policy targets runtime monitoring of executed applications. You can adjust this policy according to your scenario. You can find the MAGIC constants in the statfs(2) man page.

  10. Update kernel parameters:

    # grubby --update-kernel DEFAULT --args 'ima_appraise=fix ima_canonical_fmt ima_policy=tcb ima_template=ima-ng'
  11. Reboot the system to apply the new IMA policy.

Verification

  1. Verify that the agent is running:

    # systemctl status keylime_agent
    ● keylime_agent.service - The Keylime compute agent
         Loaded: loaded (/usr/lib/systemd/system/keylime_agent.service; enabled; preset: disabled)
         Active: active (running) since ...

Next steps

After the agent is configured on all systems you want to monitor, you can deploy Keylime to perform one or both of the following functions:

7.10. Deploying Keylime for runtime monitoring

To verify that the state of monitored systems is correct, the Keylime agent must be running on the monitored systems.

Important

Because Keylime runtime monitoring uses integrity measurement architecture (IMA) to measure large numbers of files, it might have a significant impact on the performance of your system.

When provisioning the agent, you can also define a file that Keylime sends to the monitored system. Keylime encrypts the file sent to the agent, and decrypts it only if the agent’s system complies with the TPM policy and with the IMA allowlist.

You can make Keylime ignore changes of specific files or within specific directories by configuring a Keylime excludelist. The excluded files are still measured by IMA.

From Keylime version 7.3.0, provided in RHEL 9.3, the allowlist and excludelist are combined into the Keylime runtime policy.

Prerequisites

Procedure

  1. On the monitored system where the Keylime agent is configured and running, generate an allowlist from the current state of the system:

    # /usr/share/keylime/scripts/create_allowlist.sh -o <allowlist.txt> -h sha256sum

    Replace <allowlist.txt> with the file name of the allowlist.

    Important

    Use the SHA-256 hash function. SHA-1 is not secure and has been deprecated in RHEL 9. For additional information, see SHA-1 deprecation in Red Hat Enterprise Linux 9.

  2. Copy the generated allowlist to the system where the keylime_tenant utility is configured, for example:

    # scp <allowlist.txt> root@<tenant.ip>:/root/<allowlist.txt>
  3. Optional: You can define a list of files or directories excluded from Keylime measurements by creating a file on the tenant system and entering the paths of files and directories to exclude. The excludelist accepts Python regular expressions with one regular expression per line. See Regular expression operations at docs.python.org for the complete list of special characters. Save the excludelist on the tenant system.
  4. Combine the allowlist and excludelist into the Keylime runtime policy:

    # keylime_create_policy -a <allowlist.txt> -e <excludelist.txt> -o <policy.json>
  5. On the system where the Keylime tenant is configured, provision the agent by using the keylime_tenant utility:

    # keylime_tenant -c add -t <agent_ip> -u <agent_uuid> --runtime-policy <policy.json> --cert default
    • Replace <agent_ip> with the agent’s IP address.
    • Replace <agent_uuid> with the agent’s UUID.
    • Replace <policy.json> with the path to the Keylime runtime policy file.
    • With the --cert option, the tenant generates and signs a certificate for the agent by using the CA certificates and keys located in the specified directory, or the default /var/lib/keylime/ca/ directory. If the directory contains no CA certificates and keys, the tenant will generate them automatically according to the configuration in the /etc/keylime/ca.conf file and save them to the specified directory. The tenant then sends these keys and certificates to the agent.

      When generating CA certificates or signing agent certificates, you might be prompted for the password to access the CA private key: Please enter the password to decrypt your keystore:.

      If you do not want to use a certificate, use the -f option instead for delivering a file to the agent. Provisioning an agent requires sending any file, even an empty file.

      Note

      Keylime encrypts the file sent to the agent, and decrypts it only if the agent’s system complies with the TPM policy and the IMA allowlist. By default, Keylime decompresses sent .zip files.

    As an example, with the following command, keylime_tenant provisions a new Keylime agent at 127.0.0.1 with UUID d432fbb3-d2f1-4a97-9ef7-75bd81c00000 and loads a runtime policy policy.json. It also generates a certificate in the default directory and sends the certificate file to the agent. Keylime decrypts the file only if the TPM policy configured in /etc/keylime/verifier.conf is satisfied:

    # keylime_tenant -c add -t 127.0.0.1 -u d432fbb3-d2f1-4a97-9ef7-75bd81c00000 --runtime-policy policy.json --cert default
    Note

    You can stop Keylime from monitoring a node by using the # keylime_tenant -c delete -u <agent_uuid> command.

    You can modify the configuration of an already registered agent by using the keylime_tenant -c update command.

Verification

  1. Optional: Reboot the monitored system to verify that the settings are persistent.
  2. Verify a successful attestation of the agent:

    # keylime_tenant -c cvstatus -u <agent.uuid>
    ...
    {"<agent.uuid>": {"operational_state": "Get Quote"..."attestation_count": 5
    ...

    Replace <agent.uuid> with the agent’s UUID.

    If the value of operational_state is Get Quote and attestation_count is nonzero, the attestation of this agent is successful.

    If the value of operational_state is Invalid Quote or Failed attestation fails, the command displays output similar to the following:

    {"<agent.uuid>": {"operational_state": "Invalid Quote", ... "ima.validation.ima-ng.not_in_allowlist", "attestation_count": 5, "last_received_quote": 1684150329, "last_successful_attestation": 1684150327}}
  3. If the attestation fails, display more details in the verifier log:

    # journalctl -u keylime_verifier
    keylime.tpm - INFO - Checking IMA measurement list...
    keylime.ima - WARNING - File not found in allowlist: /root/bad-script.sh
    keylime.ima - ERROR - IMA ERRORS: template-hash 0 fnf 1 hash 0 good 781
    keylime.cloudverifier - WARNING - agent D432FBB3-D2F1-4A97-9EF7-75BD81C00000 failed, stopping polling

Additional resources

7.11. Deploying Keylime for measured boot attestation

When you configure Keylime for measured boot attestation, Keylime checks that the boot process on the measured system corresponds to the state you defined.

Prerequisites

Procedure

  1. On the monitored system where the Keylime agent is configured and running, install the python3-keylime package, which contains the create_mb_refstate script:

    # dnf -y install python3-keylime
  2. On the monitored system, generate a policy from the measured boot log of the current state of the system by using the create_mb_refstate script:

    # /usr/share/keylime/scripts/create_mb_refstate /sys/kernel/security/tpm0/binary_bios_measurements <./measured_boot_reference_state.json>
    • Replace <./measured_boot_reference_state.json> with the path where the script saves the generated policy.
    • If your UEFI system does not have Secure Boot enabled, pass the --without-secureboot argument.

      Important

      The policy generated with the create_mb_refstate script is based on the current state of the system and is very strict. Any modifications of the system including kernel updates and system updates will change the boot process and the system will fail the attestation.

  3. Copy the generated policy to the system where the keylime_tenant utility is configured, for example:

    # scp root@<agent_ip>:<./measured_boot_reference_state.json> <./measured_boot_reference_state.json>
  4. On the system where the Keylime tenant is configured, provision the agent by using the keylime_tenant utility:

    # keylime_tenant -c add -t <agent_ip> -u <agent_uuid> --mb_refstate <./measured_boot_reference_state.json> --cert default
    • Replace <agent_ip> with the agent’s IP address.
    • Replace <agent_uuid> with the agent’s UUID.
    • Replace <./measured_boot_reference_state.json> with the path to the measured boot policy.

    If you configure measured boot in combination with runtime monitoring, provide all the options from both use cases when entering the keylime_tenant -c add command.

    Note

    You can stop Keylime from monitoring a node by using the # keylime_tenant -c delete -t <agent_ip> -u <agent_uuid> command.

    You can modify the configuration of an already registered agent by using the keylime_tenant -c update command.

Verification

  1. Reboot the monitored system and verify a successful attestation of the agent:

    # keylime_tenant -c cvstatus -u <agent_uuid>
    ...
    {"<agent.uuid>": {"operational_state": "Get Quote"..."attestation_count": 5
    ...

    Replace <agent_uuid> with the agent’s UUID.

    If the value of operational_state is Get Quote and attestation_count is nonzero, the attestation of this agent is successful.

    If the value of operational_state is Invalid Quote or Failed attestation fails, the command displays output similar to the following:

    {"<agent.uuid>": {"operational_state": "Invalid Quote", ... "ima.validation.ima-ng.not_in_allowlist", "attestation_count": 5, "last_received_quote": 1684150329, "last_successful_attestation": 1684150327}}
  2. If the attestation fails, display more details in the verifier log:

    # journalctl -u keylime_verifier
    {"d432fbb3-d2f1-4a97-9ef7-75bd81c00000": {"operational_state": "Tenant Quote Failed", ... "last_event_id": "measured_boot.invalid_pcr_0", "attestation_count": 0, "last_received_quote": 1684487093, "last_successful_attestation": 0}}

7.12. Keylime environment variables

You can set Keylime environment variables to override the values from the configuration files, for example, when starting a container with the podman run command by using the -e option.

The environment variables have the following syntax:

KEYLIME_<SECTION>_<ENVIRONMENT_VARIABLE>=<value>

Where:

  • <SECTION> is the section of the Keylime configuration file.
  • <ENVIRONMENT_VARIABLE> is the environment variable.
  • <value> is the value to which you want to set the environment variable.

For example, -e KEYLIME_VERIFIER_MAX_RETRIES=6 sets the max_retries configuration option in the [verifier] section to 6.

Verifier configuration
Table 7.1. [verifier] section
Configuration optionEnvironment variableDefault value

auto_migrate_db

KEYLIME_VERIFIER_AUTO_MIGRATE_DB

True

client_cert

KEYLIME_VERIFIER_CLIENT_CERT

default

client_key_password

KEYLIME_VERIFIER_CLIENT_KEY_PASSWORD

 

client_key

KEYLIME_VERIFIER_CLIENT_KEY

default

database_pool_sz_ovfl

KEYLIME_VERIFIER_DATABASE_POOL_SZ_OVFL

5,10

database_url

KEYLIME_VERIFIER_DATABASE_URL

sqlite

durable_attestation_import

KEYLIME_VERIFIER_DURABLE_ATTESTATION_IMPORT

 

enable_agent_mtls

KEYLIME_VERIFIER_ENABLE_AGENT_MTLS

True

exponential_backoff

KEYLIME_VERIFIER_EXPONENTIAL_BACKOFF

True

ignore_tomtou_errors

KEYLIME_VERIFIER_IGNORE_TOMTOU_ERRORS

False

ip

KEYLIME_VERIFIER_IP

127.0.0.1

max_retries

KEYLIME_VERIFIER_MAX_RETRIES

5

max_upload_size

KEYLIME_VERIFIER_MAX_UPLOAD_SIZE

104857600

measured_boot_evaluate

KEYLIME_VERIFIER_MEASURED_BOOT_EVALUATE

once

measured_boot_imports

KEYLIME_VERIFIER_MEASURED_BOOT_IMPORTS

[]

measured_boot_policy_name

KEYLIME_VERIFIER_MEASURED_BOOT_POLICY_NAME

accept-all

num_workers

KEYLIME_VERIFIER_NUM_WORKERS

0

persistent_store_encoding

KEYLIME_VERIFIER_PERSISTENT_STORE_ENCODING

 

persistent_store_format

KEYLIME_VERIFIER_PERSISTENT_STORE_FORMAT

json

persistent_store_url

KEYLIME_VERIFIER_PERSISTENT_STORE_URL

 

port

KEYLIME_VERIFIER_PORT

8881

quote_interval

KEYLIME_VERIFIER_QUOTE_INTERVAL

2

registrar_ip

KEYLIME_VERIFIER_REGISTRAR_IP

127.0.0.1

registrar_port

KEYLIME_VERIFIER_REGISTRAR_PORT

8891

request_timeout

KEYLIME_VERIFIER_REQUEST_TIMEOUT

60.0

require_allow_list_signatures

KEYLIME_VERIFIER_REQUIRE_ALLOW_LIST_SIGNATURES

True

retry_interval

KEYLIME_VERIFIER_RETRY_INTERVAL

2

server_cert

KEYLIME_VERIFIER_SERVER_CERT

default

server_key_password

KEYLIME_VERIFIER_SERVER_KEY_PASSWORD

default

server_key

KEYLIME_VERIFIER_SERVER_KEY

default

severity_labels

KEYLIME_VERIFIER_SEVERITY_LABELS

["info", "notice", "warning", "error", "critical", "alert", "emergency"]

severity_policy

KEYLIME_VERIFIER_SEVERITY_POLICY

[{"event_id": ".*", "severity_label" : "emergency"}]

signed_attributes

KEYLIME_VERIFIER_SIGNED_ATTRIBUTES

 

time_stamp_authority_certs_path

KEYLIME_VERIFIER_TIME_STAMP_AUTHORITY_CERTS_PATH

 

time_stamp_authority_url

KEYLIME_VERIFIER_TIME_STAMP_AUTHORITY_URL

 

tls_dir

KEYLIME_VERIFIER_TLS_DIR

generate

transparency_log_sign_algo

KEYLIME_VERIFIER_TRANSPARENCY_LOG_SIGN_ALGO

sha256

transparency_log_url

KEYLIME_VERIFIER_TRANSPARENCY_LOG_URL

 

trusted_client_ca

KEYLIME_VERIFIER_TRUSTED_CLIENT_CA

default

trusted_server_ca

KEYLIME_VERIFIER_TRUSTED_SERVER_CA

default

uuid

KEYLIME_VERIFIER_UUID

default

version

KEYLIME_VERIFIER_VERSION

2.0

Table 7.2. [revocations] section

Configuration option

Environment variable

Default value

enabled_revocation_notifications

KEYLIME_VERIFIER_REVOCATIONS_ENABLED_REVOCATION_NOTIFICATIONS

[agent]

webhook_url

KEYLIME_VERIFIER_REVOCATIONS_WEBHOOK_URL

 
Registrar configuration
Table 7.3. [registrar] section

Configuration option

Environment variable

Default value

auto_migrate_db

KEYLIME_REGISTRAR_AUTO_MIGRATE_DB

True

database_pool_sz_ovfl

KEYLIME_REGISTRAR_DATABASE_POOL_SZ_OVFL

5,10

database_url

KEYLIME_REGISTRAR_DATABASE_URL

sqlite

durable_attestation_import

KEYLIME_REGISTRAR_DURABLE_ATTESTATION_IMPORT

 

ip

KEYLIME_REGISTRAR_IP

127.0.0.1

persistent_store_encoding

KEYLIME_REGISTRAR_PERSISTENT_STORE_ENCODING

 

persistent_store_format

KEYLIME_REGISTRAR_PERSISTENT_STORE_FORMAT

json

persistent_store_url

KEYLIME_REGISTRAR_PERSISTENT_STORE_URL

 

port

KEYLIME_REGISTRAR_PORT

8890

prov_db_filename

KEYLIME_REGISTRAR_PROV_DB_FILENAME

provider_reg_data.sqlite

server_cert

KEYLIME_REGISTRAR_SERVER_CERT

default

server_key_password

KEYLIME_REGISTRAR_SERVER_KEY_PASSWORD

default

server_key

KEYLIME_REGISTRAR_SERVER_KEY

default

signed_attributes

KEYLIME_REGISTRAR_SIGNED_ATTRIBUTES

ek_tpm,aik_tpm,ekcert

time_stamp_authority_certs_path

KEYLIME_REGISTRAR_TIME_STAMP_AUTHORITY_CERTS_PATH

 

time_stamp_authority_url

KEYLIME_REGISTRAR_TIME_STAMP_AUTHORITY_URL

 

tls_dir

KEYLIME_REGISTRAR_TLS_DIR

default

tls_port

KEYLIME_REGISTRAR_TLS_PORT

8891

transparency_log_sign_algo

KEYLIME_REGISTRAR_TRANSPARENCY_LOG_SIGN_ALGO

sha256

transparency_log_url

KEYLIME_REGISTRAR_TRANSPARENCY_LOG_URL

 

trusted_client_ca

KEYLIME_REGISTRAR_TRUSTED_CLIENT_CA

default

version

KEYLIME_REGISTRAR_VERSION

2.0

Tenant configuration
Table 7.4. [tenant] section

Configuration option

Environment variable

Default value

accept_tpm_encryption_algs

KEYLIME_TENANT_ACCEPT_TPM_ENCRYPTION_ALGS

ecc, rsa

accept_tpm_hash_algs

KEYLIME_TENANT_ACCEPT_TPM_HASH_ALGS

sha512, sha384, sha256

accept_tpm_signing_algs

KEYLIME_TENANT_ACCEPT_TPM_SIGNING_ALGS

ecschnorr, rsassa

client_cert

KEYLIME_TENANT_CLIENT_CERT

default

client_key_password

KEYLIME_TENANT_CLIENT_KEY_PASSWORD

 

client_key

KEYLIME_TENANT_CLIENT_KEY

default

ek_check_script

KEYLIME_TENANT_EK_CHECK_SCRIPT

 

enable_agent_mtls

KEYLIME_TENANT_ENABLE_AGENT_MTLS

True

exponential_backoff

KEYLIME_TENANT_EXPONENTIAL_BACKOFF

True

max_payload_size

KEYLIME_TENANT_MAX_PAYLOAD_SIZE

1048576

max_retries

KEYLIME_TENANT_MAX_RETRIES

5

mb_refstate

KEYLIME_TENANT_MB_REFSTATE

 

registrar_ip

KEYLIME_TENANT_REGISTRAR_IP

127.0.0.1

registrar_port

KEYLIME_TENANT_REGISTRAR_PORT

8891

request_timeout

KEYLIME_TENANT_REQUEST_TIMEOUT

60

require_ek_cert

KEYLIME_TENANT_REQUIRE_EK_CERT

True

retry_interval

KEYLIME_TENANT_RETRY_INTERVAL

2

tls_dir

KEYLIME_TENANT_TLS_DIR

default

tpm_cert_store

KEYLIME_TENANT_TPM_CERT_STORE

/var/lib/keylime/tpm_cert_store

trusted_server_ca

KEYLIME_TENANT_TRUSTED_SERVER_CA

default

verifier_ip

KEYLIME_TENANT_VERIFIER_IP

127.0.0.1

verifier_port

KEYLIME_TENANT_VERIFIER_PORT

8881

version

KEYLIME_TENANT_VERSION

2.0

CA configuration
Table 7.5. [ca] section

Configuration option

Environment variable

Default value

cert_bits

KEYLIME_CA_CERT_BITS

2048

cert_ca_lifetime

KEYLIME_CA_CERT_CA_LIFETIME

3650

cert_ca_name

KEYLIME_CA_CERT_CA_NAME

Keylime Certificate Authority

cert_country

KEYLIME_CA_CERT_COUNTRY

US

cert_crl_dist

KEYLIME_CA_CERT_CRL_DIST

http://localhost:38080/crl

cert_lifetime

KEYLIME_CA_CERT_LIFETIME

365

cert_locality

KEYLIME_CA_CERT_LOCALITY

Lexington

cert_org_unit

KEYLIME_CA_CERT_ORG_UNIT

53

cert_organization

KEYLIME_CA_CERT_ORGANIZATION

MITLL

cert_state

KEYLIME_CA_CERT_STATE

MA

password

KEYLIME_CA_PASSWORD

default

version

KEYLIME_CA_VERSION

2.0

Agent configuration
Table 7.6. [agent] section
Configuration optionEnvironment variableDefault value

contact_ip

KEYLIME_AGENT_CONTACT_IP

127.0.0.1

contact_port

KEYLIME_AGENT_CONTACT_PORT

9002

dec_payload_file

KEYLIME_AGENT_DEC_PAYLOAD_FILE

decrypted_payload

ek_handle

KEYLIME_AGENT_EK_HANDLE

generate

enable_agent_mtls

KEYLIME_AGENT_ENABLE_AGENT_MTLS

true

enable_insecure_payload

KEYLIME_AGENT_ENABLE_INSECURE_PAYLOAD

false

enable_revocation_notifications

KEYLIME_AGENT_ENABLE_REVOCATION_NOTIFICATIONS

true

enc_keyname

KEYLIME_AGENT_ENC_KEYNAME

derived_tci_key

exponential_backoff

KEYLIME_AGENT_EXPONENTIAL_BACKOFF

true

extract_payload_zip

KEYLIME_AGENT_EXTRACT_PAYLOAD_ZIP

true

ip

KEYLIME_AGENT_IP

127.0.0.1

max_retries

KEYLIME_AGENT_MAX_RETRIES

4

measure_payload_pcr

KEYLIME_AGENT_MEASURE_PAYLOAD_PCR

-1

payload_script

KEYLIME_AGENT_PAYLOAD_SCRIPT

autorun.sh

port

KEYLIME_AGENT_PORT

9002

registrar_ip

KEYLIME_AGENT_REGISTRAR_IP

127.0.0.1

registrar_port

KEYLIME_AGENT_REGISTRAR_PORT

8890

retry_interval

KEYLIME_AGENT_RETRY_INTERVAL

2

revocation_actions

KEYLIME_AGENT_REVOCATION_ACTIONS

[]

revocation_cert

KEYLIME_AGENT_REVOCATION_CERT

default

revocation_notification_ip

KEYLIME_AGENT_REVOCATION_NOTIFICATION_IP

127.0.0.1

revocation_notification_port

KEYLIME_AGENT_REVOCATION_NOTIFICATION_PORT

8992

run_as

KEYLIME_AGENT_RUN_AS

keylime:tss

secure_size

KEYLIME_AGENT_SECURE_SIZE

1m

server_cert

KEYLIME_AGENT_SERVER_CERT

default

server_key_password

KEYLIME_AGENT_SERVER_KEY_PASSWORD

 

server_key

KEYLIME_AGENT_SERVER_KEY

default

tls_dir

KEYLIME_AGENT_TLS_DIR

default

tpm_encryption_alg

KEYLIME_AGENT_TPM_ENCRYPTION_ALG

rsa

tpm_hash_alg

KEYLIME_AGENT_TPM_HASH_ALG

sha256

tpm_ownerpassword

KEYLIME_AGENT_TPM_OWNERPASSWORD

 

tpm_signing_alg

KEYLIME_AGENT_TPM_SIGNING_ALG

rsassa

trusted_client_ca

KEYLIME_AGENT_TRUSTED_CLIENT_CA

default

uuid

KEYLIME_AGENT_UUID

d432fbb3-d2f1-4a97-9ef7-75bd81c00000

version

KEYLIME_AGENT_VERSION

2.0

Logging configuration
Table 7.7. [logging] section

Configuration option

Environment variable

Default value

version

KEYLIME_LOGGING_VERSION

2.0

Table 7.8. [loggers] section

Configuration option

Environment variable

Default value

keys

KEYLIME_LOGGING_LOGGERS_KEYS

root,keylime

Table 7.9. [handlers] section

Configuration option

Environment variable

Default value

keys

KEYLIME_LOGGING_HANDLERS_KEYS

consoleHandler

Table 7.10. [formatters] section

Configuration option

Environment variable

Default value

keys

KEYLIME_LOGGING_FORMATTERS_KEYS

formatter

Table 7.11. [formatter_formatter] section

Configuration option

Environment variable

Default value

datefmt

KEYLIME_LOGGING_FORMATTER_FORMATTER_DATEFMT

%Y-%m-%d %H:%M:%S

format

KEYLIME_LOGGING_FORMATTER_FORMATTER_FORMAT

%(asctime)s.%(msecs)03d - %(name)s - %(levelname)s - %(message)s

Table 7.12. [logger_root] section

Configuration option

Environment variable

Default value

handlers

KEYLIME_LOGGING_LOGGER_ROOT_HANDLERS

consoleHandler

level

KEYLIME_LOGGING_LOGGER_ROOT_LEVEL

INFO

Table 7.13. [handler_consoleHandler] section

Configuration option

Environment variable

Default value

args

KEYLIME_LOGGING_HANDLER_CONSOLEHANDLER_ARGS

(sys.stdout,)

class

KEYLIME_LOGGING_HANDLER_CONSOLEHANDLER_CLASS

StreamHandler

formatter

KEYLIME_LOGGING_HANDLER_CONSOLEHANDLER_FORMATTER

formatter

level

KEYLIME_LOGGING_HANDLER_CONSOLEHANDLER_LEVEL

INFO

Table 7.14. [logger_keylime] section

Configuration option

Environment variable

Default value

handlers

KEYLIME_LOGGING_LOGGER_KEYLIME_HANDLERS

 

level

KEYLIME_LOGGING_LOGGER_KEYLIME_LEVEL

INFO

qualname

KEYLIME_LOGGING_LOGGER_KEYLIME_QUALNAME

keylime

Chapter 8. Checking integrity with AIDE

Advanced Intrusion Detection Environment (AIDE) is a utility that creates a database of files on the system, and then uses that database to ensure file integrity and detect system intrusions.

8.1. Installing AIDE

To start file-integrity checking with AIDE, you must install the corresponding package and initiate the AIDE database.

Prerequisites

  • The AppStream repository is enabled.

Procedure

  1. Install the aide package:

    # dnf install aide
  2. Generate an initial database:

    # aide --init
    Start timestamp: 2024-07-08 10:39:23 -0400 (AIDE 0.16)
    AIDE initialized database at /var/lib/aide/aide.db.new.gz
    
    Number of entries:	55856
    
    ---------------------------------------------------
    The attributes of the (uncompressed) database(s):
    ---------------------------------------------------
    
    /var/lib/aide/aide.db.new.gz
    …
      SHA512   : mZaWoGzL2m6ZcyyZ/AXTIowliEXWSZqx
                 IFYImY4f7id4u+Bq8WeuSE2jasZur/A4
                 FPBFaBkoCFHdoE/FW/V94Q==
  3. Optional: In the default configuration, the aide --init command checks just a set of directories and files defined in the /etc/aide.conf file. To include additional directories or files in the AIDE database, and to change their watched parameters, edit /etc/aide.conf accordingly.
  4. To start using the database, remove the .new substring from the initial database file name:

    # mv /var/lib/aide/aide.db.new.gz /var/lib/aide/aide.db.gz
  5. Optional: To change the location of the AIDE database, edit the /etc/aide.conf file and modify the DBDIR value. For additional security, store the database, configuration, and the /usr/sbin/aide binary file in a secure location such as a read-only media.

8.2. Performing integrity checks with AIDE

You can use the crond service to schedule regular file-integrity checks with AIDE.

Prerequisites

  • AIDE is properly installed and its database is initialized. See Installing AIDE

Procedure

  1. To initiate a manual check:

    # aide --check
    Start timestamp: 2024-07-08 10:43:46 -0400 (AIDE 0.16)
    AIDE found differences between database and filesystem!!
    
    Summary:
      Total number of entries:	55856
      Added entries:		0
      Removed entries:		0
      Changed entries:		1
    
    ---------------------------------------------------
    Changed entries:
    ---------------------------------------------------
    
    f   ...      ..S : /root/.viminfo
    
    ---------------------------------------------------
    Detailed information about changes:
    ---------------------------------------------------
    
    File: /root/.viminfo
      SELinux  : system_u:object_r:admin_home_t:s | unconfined_u:object_r:admin_home
                 0                                | _t:s0
    …
  2. At a minimum, configure the system to run AIDE weekly. Optimally, run AIDE daily. For example, to schedule a daily execution of AIDE at 04:05 a.m. by using the cron command, add the following line to the /etc/crontab file:

     05 4 * * * root /usr/sbin/aide --check

Additional resources

  • cron(8) man page on your system

8.3. Updating an AIDE database

After verifying the changes of your system, such as package updates or configuration files adjustments, update also your baseline AIDE database.

Prerequisites

  • AIDE is properly installed and its database is initialized. See Installing AIDE

Procedure

  1. Update your baseline AIDE database:

    # aide --update

    The aide --update command creates the /var/lib/aide/aide.db.new.gz database file.

  2. To start using the updated database for integrity checks, remove the .new substring from the file name.

8.4. File-integrity tools: AIDE and IMA

Red Hat Enterprise Linux provides several tools for checking and preserving the integrity of files and directories on your system. The following table helps you decide which tool better fits your scenario.

Table 8.1. Comparison between AIDE and IMA
QuestionAdvanced Intrusion Detection Environment (AIDE)Integrity Measurement Architecture (IMA)

What

AIDE is a utility that creates a database of files and directories on the system. This database serves for checking file integrity and detect intrusion detection.

IMA detects if a file is altered by checking file measurement (hash values) compared to previously stored extended attributes.

How

AIDE uses rules to compare the integrity state of the files and directories.

IMA uses file hash values to detect the intrusion.

Why

Detection - AIDE detects if a file is modified by verifying the rules.

Detection and Prevention - IMA detects and prevents an attack by replacing the extended attribute of a file.

Usage

AIDE detects a threat when the file or directory is modified.

IMA detects a threat when someone tries to alter the entire file.

Extension

AIDE checks the integrity of files and directories on the local system.

IMA ensures security on the local and remote systems.

Chapter 9. Encrypting block devices using LUKS

By using the disk encryption, you can protect the data on a block device by encrypting it. To access the device’s decrypted contents, enter a passphrase or key as authentication. This is important for mobile computers and removable media because it helps to protect the device’s contents even if it has been physically removed from the system. The LUKS format is a default implementation of block device encryption in Red Hat Enterprise Linux.

9.1. LUKS disk encryption

Linux Unified Key Setup-on-disk-format (LUKS) provides a set of tools that simplifies managing the encrypted devices. With LUKS, you can encrypt block devices and enable multiple user keys to decrypt a master key. For bulk encryption of the partition, use this master key.

Red Hat Enterprise Linux uses LUKS to perform block device encryption. By default, the option to encrypt the block device is unchecked during the installation. If you select the option to encrypt your disk, the system prompts you for a passphrase every time you boot the computer. This passphrase unlocks the bulk encryption key that decrypts your partition. If you want to modify the default partition table, you can select the partitions that you want to encrypt. This is set in the partition table settings.

Ciphers

The default cipher used for LUKS is aes-xts-plain64. The default key size for LUKS is 512 bits. The default key size for LUKS with Anaconda XTS mode is 512 bits. The following are the available ciphers:

  • Advanced Encryption Standard (AES)
  • Twofish
  • Serpent

Operations performed by LUKS

  • LUKS encrypts entire block devices and is therefore well-suited for protecting contents of mobile devices such as removable storage media or laptop disk drives.
  • The underlying contents of the encrypted block device are arbitrary, which makes it useful for encrypting swap devices. This can also be useful with certain databases that use specially formatted block devices for data storage.
  • LUKS uses the existing device mapper kernel subsystem.
  • LUKS provides passphrase strengthening, which protects against dictionary attacks.
  • LUKS devices contain multiple key slots, which means you can add backup keys or passphrases.
Important

LUKS is not recommended for the following scenarios:

  • Disk-encryption solutions such as LUKS protect the data only when your system is off. After the system is on and LUKS has decrypted the disk, the files on that disk are available to anyone who have access to them.
  • Scenarios that require multiple users to have distinct access keys to the same device. The LUKS1 format provides eight key slots and LUKS2 provides up to 32 key slots.
  • Applications that require file-level encryption.

9.2. LUKS versions in RHEL

In Red Hat Enterprise Linux, the default format for LUKS encryption is LUKS2. The old LUKS1 format remains fully supported and it is provided as a format compatible with earlier Red Hat Enterprise Linux releases. LUKS2 re-encryption is considered more robust and safe to use as compared to LUKS1 re-encryption.

The LUKS2 format enables future updates of various parts without a need to modify binary structures. Internally it uses JSON text format for metadata, provides redundancy of metadata, detects metadata corruption, and automatically repairs from a metadata copy.

Important

Do not use LUKS2 in systems that support only LUKS1.

Since Red Hat Enterprise Linux 9.2, you can use the cryptsetup reencrypt command for both the LUKS versions to encrypt the disk.

Online re-encryption

The LUKS2 format supports re-encrypting encrypted devices while the devices are in use. For example, you do not have to unmount the file system on the device to perform the following tasks:

  • Changing the volume key
  • Changing the encryption algorithm

    When encrypting a non-encrypted device, you must still unmount the file system. You can remount the file system after a short initialization of the encryption.

    The LUKS1 format does not support online re-encryption.

Conversion

In certain situations, you can convert LUKS1 to LUKS2. The conversion is not possible specifically in the following scenarios:

  • A LUKS1 device is marked as being used by a Policy-Based Decryption (PBD) Clevis solution. The cryptsetup tool does not convert the device when some luksmeta metadata are detected.
  • A device is active. The device must be in an inactive state before any conversion is possible.

9.3. Options for data protection during LUKS2 re-encryption

LUKS2 provides several options that prioritize performance or data protection during the re-encryption process. It provides the following modes for the resilience option, and you can select any of these modes by using the cryptsetup reencrypt --resilience resilience-mode /dev/sdx command:

checksum

The default mode. It balances data protection and performance.

This mode stores individual checksums of the sectors in the re-encryption area, which the recovery process can detect for the sectors that were re-encrypted by LUKS2. The mode requires that the block device sector write is atomic.

journal
The safest mode but also the slowest. Since this mode journals the re-encryption area in the binary area, the LUKS2 writes the data twice.
none
The none mode prioritizes performance and provides no data protection. It protects the data only against safe process termination, such as the SIGTERM signal or the user pressing Ctrl+C key. Any unexpected system failure or application failure might result in data corruption.

If a LUKS2 re-encryption process terminates unexpectedly by force, LUKS2 can perform the recovery in one of the following ways:

Automatically

By performing any one of the following actions triggers the automatic recovery action during the next LUKS2 device open action:

  • Executing the cryptsetup open command.
  • Attaching the device with the systemd-cryptsetup command.
Manually
By using the cryptsetup repair /dev/sdx command on the LUKS2 device.

Additional resources

  • cryptsetup-reencrypt(8) and cryptsetup-repair(8) man pages

9.4. Encrypting existing data on a block device using LUKS2

You can encrypt the existing data on a not yet encrypted device by using the LUKS2 format. A new LUKS header is stored in the head of the device.

Prerequisites

  • The block device has a file system.
  • You have backed up your data.

    Warning

    You might lose your data during the encryption process due to a hardware, kernel, or human failure. Ensure that you have a reliable backup before you start encrypting the data.

Procedure

  1. Unmount all file systems on the device that you plan to encrypt, for example:

    # umount /dev/mapper/vg00-lv00
  2. Make free space for storing a LUKS header. Use one of the following options that suits your scenario:

    • In the case of encrypting a logical volume, you can extend the logical volume without resizing the file system. For example:

      # lvextend -L+32M /dev/mapper/vg00-lv00
    • Extend the partition by using partition management tools, such as parted.
    • Shrink the file system on the device. You can use the resize2fs utility for the ext2, ext3, or ext4 file systems. Note that you cannot shrink the XFS file system.
  3. Initialize the encryption:

    # cryptsetup reencrypt --encrypt --init-only --reduce-device-size 32M /dev/mapper/vg00-lv00 lv00_encrypted
    
    /dev/mapper/lv00_encrypted is now active and ready for online encryption.
  4. Mount the device:

    # mount /dev/mapper/lv00_encrypted /mnt/lv00_encrypted
  5. Add an entry for a persistent mapping to the /etc/crypttab file:

    1. Find the luksUUID:

      # cryptsetup luksUUID /dev/mapper/vg00-lv00
      
      a52e2cc9-a5be-47b8-a95d-6bdf4f2d9325
    2. Open /etc/crypttab in a text editor of your choice and add a device in this file:

      $ vi /etc/crypttab
      
      lv00_encrypted UUID=a52e2cc9-a5be-47b8-a95d-6bdf4f2d9325 none

      Replace a52e2cc9-a5be-47b8-a95d-6bdf4f2d9325 with your device’s luksUUID.

    3. Refresh initramfs with dracut:

      $ dracut -f --regenerate-all
  6. Add an entry for a persistent mounting to the /etc/fstab file:

    1. Find the file system’s UUID of the active LUKS block device:

      $ blkid -p /dev/mapper/lv00_encrypted
      
      /dev/mapper/lv00-encrypted: UUID="37bc2492-d8fa-4969-9d9b-bb64d3685aa9" BLOCK_SIZE="4096" TYPE="xfs" USAGE="filesystem"
    2. Open /etc/fstab in a text editor of your choice and add a device in this file, for example:

      $ vi /etc/fstab
      
      UUID=37bc2492-d8fa-4969-9d9b-bb64d3685aa9 /home auto rw,user,auto 0

      Replace 37bc2492-d8fa-4969-9d9b-bb64d3685aa9 with your file system’s UUID.

  7. Resume the online encryption:

    # cryptsetup reencrypt --resume-only /dev/mapper/vg00-lv00
    
    Enter passphrase for /dev/mapper/vg00-lv00:
    Auto-detected active dm device 'lv00_encrypted' for data device /dev/mapper/vg00-lv00.
    Finished, time 00:31.130, 10272 MiB written, speed 330.0 MiB/s

Verification

  1. Verify if the existing data was encrypted:

    # cryptsetup luksDump /dev/mapper/vg00-lv00
    
    LUKS header information
    Version: 2
    Epoch: 4
    Metadata area: 16384 [bytes]
    Keyslots area: 16744448 [bytes]
    UUID: a52e2cc9-a5be-47b8-a95d-6bdf4f2d9325
    Label: (no label)
    Subsystem: (no subsystem)
    Flags: (no flags)
    
    Data segments:
      0: crypt
    	offset: 33554432 [bytes]
    	length: (whole device)
    	cipher: aes-xts-plain64
    [...]
  2. View the status of the encrypted blank block device:

    # cryptsetup status lv00_encrypted
    
    /dev/mapper/lv00_encrypted is active and is in use.
      type:    LUKS2
      cipher:  aes-xts-plain64
      keysize: 512 bits
      key location: keyring
      device:  /dev/mapper/vg00-lv00

Additional resources

  • cryptsetup(8), cryptsetup-reencrypt(8), lvextend(8), resize2fs(8), and parted(8) man pages

9.5. Encrypting existing data on a block device using LUKS2 with a detached header

You can encrypt existing data on a block device without creating free space for storing a LUKS header. The header is stored in a detached location, which also serves as an additional layer of security. The procedure uses the LUKS2 encryption format.

Prerequisites

  • The block device has a file system.
  • You have backed up your data.

    Warning

    You might lose your data during the encryption process due to a hardware, kernel, or human failure. Ensure that you have a reliable backup before you start encrypting the data.

Procedure

  1. Unmount all file systems on the device, for example:

    # umount /dev/nvme0n1p1
  2. Initialize the encryption:

    # cryptsetup reencrypt --encrypt --init-only --header /home/header /dev/nvme0n1p1 nvme_encrypted
    
    WARNING!
    ========
    Header file does not exist, do you want to create it?
    
    Are you sure? (Type 'yes' in capital letters): YES
    Enter passphrase for /home/header:
    Verify passphrase:
    /dev/mapper/nvme_encrypted is now active and ready for online encryption.

    Replace /home/header with a path to the file with a detached LUKS header. The detached LUKS header has to be accessible to unlock the encrypted device later.

  3. Mount the device:

    # mount /dev/mapper/nvme_encrypted /mnt/nvme_encrypted
  4. Resume the online encryption:

    # cryptsetup reencrypt --resume-only --header /home/header /dev/nvme0n1p1
    
    Enter passphrase for /dev/nvme0n1p1:
    Auto-detected active dm device 'nvme_encrypted' for data device /dev/nvme0n1p1.
    Finished, time 00m51s,   10 GiB written, speed 198.2 MiB/s

Verification

  1. Verify if the existing data on a block device using LUKS2 with a detached header is encrypted:

    # cryptsetup luksDump /home/header
    
    LUKS header information
    Version:       	2
    Epoch:         	88
    Metadata area: 	16384 [bytes]
    Keyslots area: 	16744448 [bytes]
    UUID:          	c4f5d274-f4c0-41e3-ac36-22a917ab0386
    Label:         	(no label)
    Subsystem:     	(no subsystem)
    Flags:       	(no flags)
    
    Data segments:
      0: crypt
    	offset: 0 [bytes]
    	length: (whole device)
    	cipher: aes-xts-plain64
    	sector: 512 [bytes]
    [...]
  2. View the status of the encrypted blank block device:

    # cryptsetup status nvme_encrypted
    
    /dev/mapper/nvme_encrypted is active and is in use.
      type:    LUKS2
      cipher:  aes-xts-plain64
      keysize: 512 bits
      key location: keyring
      device:  /dev/nvme0n1p1

Additional resources

  • cryptsetup(8) and cryptsetup-reencrypt(8) man pages

9.6. Encrypting a blank block device using LUKS2

You can encrypt a blank block device, which you can use for an encrypted storage by using the LUKS2 format.

Prerequisites

  • A blank block device. You can use commands such as lsblk to find if there is no real data on that device, for example, a file system.

Procedure

  1. Setup a partition as an encrypted LUKS partition:

    # cryptsetup luksFormat /dev/nvme0n1p1
    
    WARNING!
    ========
    This will overwrite data on /dev/nvme0n1p1 irrevocably.
    Are you sure? (Type 'yes' in capital letters): YES
    Enter passphrase for /dev/nvme0n1p1:
    Verify passphrase:
  2. Open an encrypted LUKS partition:

    # cryptsetup open /dev/nvme0n1p1 nvme0n1p1_encrypted
    
    Enter passphrase for /dev/nvme0n1p1:

    This unlocks the partition and maps it to a new device by using the device mapper. To not overwrite the encrypted data, this command alerts the kernel that the device is an encrypted device and addressed through LUKS by using the /dev/mapper/device_mapped_name path.

  3. Create a file system to write encrypted data to the partition, which must be accessed through the device mapped name:

    # mkfs -t ext4 /dev/mapper/nvme0n1p1_encrypted
  4. Mount the device:

    # mount /dev/mapper/nvme0n1p1_encrypted mount-point

Verification

  1. Verify if the blank block device is encrypted:

    # cryptsetup luksDump /dev/nvme0n1p1
    
    LUKS header information
    Version:       	2
    Epoch:         	3
    Metadata area: 	16384 [bytes]
    Keyslots area: 	16744448 [bytes]
    UUID:          	34ce4870-ffdf-467c-9a9e-345a53ed8a25
    Label:         	(no label)
    Subsystem:     	(no subsystem)
    Flags:       	(no flags)
    
    Data segments:
      0: crypt
    	offset: 16777216 [bytes]
    	length: (whole device)
    	cipher: aes-xts-plain64
    	sector: 512 [bytes]
    [...]
  2. View the status of the encrypted blank block device:

    # cryptsetup status nvme0n1p1_encrypted
    
    /dev/mapper/nvme0n1p1_encrypted is active and is in use.
      type:    LUKS2
      cipher:  aes-xts-plain64
      keysize: 512 bits
      key location: keyring
      device:  /dev/nvme0n1p1
      sector size:  512
      offset:  32768 sectors
      size:    20938752 sectors
      mode:    read/write

Additional resources

  • cryptsetup(8), cryptsetup-open (8), and cryptsetup-lusFormat(8) man pages

9.7. Creating a LUKS2 encrypted volume by using the storage RHEL system role

You can use the storage role to create and configure a volume encrypted with LUKS by running an Ansible playbook.

Prerequisites

Procedure

  1. Create a playbook file, for example ~/playbook.yml, with the following content:

    ---
    - name: Create and configure a volume encrypted with LUKS
      hosts: managed-node-01.example.com
      roles:
        - rhel-system-roles.storage
      vars:
        storage_volumes:
          - name: barefs
            type: disk
            disks:
             - sdb
            fs_type: xfs
            fs_label: label-name
            mount_point: /mnt/data
            encryption: true
            encryption_password: <password>

    You can also add other encryption parameters, such as encryption_key, encryption_cipher, encryption_key_size, and encryption_luks, to the playbook file.

  2. Validate the playbook syntax:

    $ ansible-playbook --syntax-check ~/playbook.yml

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    $ ansible-playbook ~/playbook.yml

Verification

  1. View the encryption status:

    # cryptsetup status sdb
    
    /dev/mapper/sdb is active and is in use.
    type: LUKS2
    cipher: aes-xts-plain64
    keysize: 512 bits
    key location: keyring
    device: /dev/sdb
    ...
  2. Verify the created LUKS encrypted volume:

    # cryptsetup luksDump /dev/sdb
    
    Version:        2
    Epoch:          6
    Metadata area:  16384 [bytes]
    Keyslots area:  33521664 [bytes]
    UUID:           a4c6be82-7347-4a91-a8ad-9479b72c9426
    Label:          (no label)
    Subsystem:      (no subsystem)
    Flags:          allow-discards
    
    Data segments:
      0: crypt
            offset: 33554432 [bytes]
            length: (whole device)
            cipher: aes-xts-plain64
            sector: 4096 [bytes]
    ...

Additional resources

Chapter 10. Configuring automated unlocking of encrypted volumes by using policy-based decryption

Policy-Based Decryption (PBD) is a collection of technologies that enable unlocking encrypted root and secondary volumes of hard drives on physical and virtual machines. PBD uses a variety of unlocking methods, such as user passwords, a Trusted Platform Module (TPM) device, a PKCS #11 device connected to a system, for example, a smart card, or a special network server.

PBD allows combining different unlocking methods into a policy, which makes it possible to unlock the same volume in different ways. The current implementation of the PBD in RHEL consists of the Clevis framework and plug-ins called pins. Each pin provides a separate unlocking capability. Currently, the following pins are available:

tang
Allows unlocking volumes using a network server.
tpm2
allows unlocking volumes using a TPM2 policy.
sss
allows deploying high-availability systems using the Shamir’s Secret Sharing (SSS) cryptographic scheme.

10.1. Network-bound disk encryption

The Network Bound Disc Encryption (NBDE) is a subcategory of Policy-Based Decryption (PBD) that allows binding encrypted volumes to a special network server. The current implementation of the NBDE includes a Clevis pin for the Tang server and the Tang server itself.

In RHEL, NBDE is implemented through the following components and technologies:

Figure 10.1. NBDE scheme when using a LUKS1-encrypted volume. The luksmeta package is not used for LUKS2 volumes.

Network-Bound Disk Encryption (NBDE)

Tang is a server for binding data to network presence. It makes a system containing your data available when the system is bound to a certain secure network. Tang is stateless and does not require TLS or authentication. Unlike escrow-based solutions, where the server stores all encryption keys and has knowledge of every key ever used, Tang never interacts with any client keys, so it never gains any identifying information from the client.

Clevis is a pluggable framework for automated decryption. In NBDE, Clevis provides automated unlocking of LUKS volumes. The clevis package provides the client side of the feature.

A Clevis pin is a plug-in into the Clevis framework. One of such pins is a plug-in that implements interactions with the NBDE server — Tang.

Clevis and Tang are generic client and server components that provide network-bound encryption. In RHEL, they are used in conjunction with LUKS to encrypt and decrypt root and non-root storage volumes to accomplish Network-Bound Disk Encryption.

Both client- and server-side components use the José library to perform encryption and decryption operations.

When you begin provisioning NBDE, the Clevis pin for Tang server gets a list of the Tang server’s advertised asymmetric keys. Alternatively, since the keys are asymmetric, a list of Tang’s public keys can be distributed out of band so that clients can operate without access to the Tang server. This mode is called offline provisioning.

The Clevis pin for Tang uses one of the public keys to generate a unique, cryptographically-strong encryption key. Once the data is encrypted using this key, the key is discarded. The Clevis client should store the state produced by this provisioning operation in a convenient location. This process of encrypting data is the provisioning step.

The LUKS version 2 (LUKS2) is the default disk-encryption format in RHEL, hence, the provisioning state for NBDE is stored as a token in a LUKS2 header. The leveraging of provisioning state for NBDE by the luksmeta package is used only for volumes encrypted with LUKS1.

The Clevis pin for Tang supports both LUKS1 and LUKS2 without specification need. Clevis can encrypt plain-text files but you have to use the cryptsetup tool for encrypting block devices. See the Encrypting block devices using LUKS for more information.

When the client is ready to access its data, it loads the metadata produced in the provisioning step and it responds to recover the encryption key. This process is the recovery step.

In NBDE, Clevis binds a LUKS volume using a pin so that it can be automatically unlocked. After successful completion of the binding process, the disk can be unlocked using the provided Dracut unlocker.

Note

If the kdump kernel crash dumping mechanism is set to save the content of the system memory to a LUKS-encrypted device, you are prompted for entering a password during the second kernel boot.

Additional resources

10.2. Installing an encryption client - Clevis

To configure automated unlocking of encrypted volumes, you must deploy the Clevis pluggable framework on your client systems first.

Procedure

  1. To install Clevis and its pins on a system with an encrypted volume:

    # dnf install clevis
  2. To decrypt data, use a clevis decrypt command and provide a cipher text in the JSON Web Encryption (JWE) format, for example:

    $ clevis decrypt < secret.jwe

Additional resources

  • clevis(1) man page
  • Built-in CLI help after entering the clevis command without any argument:

    $ clevis
    Usage: clevis COMMAND [OPTIONS]
    
    clevis decrypt      Decrypts using the policy defined at encryption time
    clevis encrypt sss  Encrypts using a Shamir's Secret Sharing policy
    clevis encrypt tang Encrypts using a Tang binding server policy
    clevis encrypt tpm2 Encrypts using a TPM2.0 chip binding policy
    clevis luks bind    Binds a LUKS device using the specified policy
    clevis luks edit    Edit a binding from a clevis-bound slot in a LUKS device
    clevis luks list    Lists pins bound to a LUKSv1 or LUKSv2 device
    clevis luks pass    Returns the LUKS passphrase used for binding a particular slot.
    clevis luks regen   Regenerate clevis binding
    clevis luks report  Report tang keys' rotations
    clevis luks unbind  Unbinds a pin bound to a LUKS volume
    clevis luks unlock  Unlocks a LUKS volume

10.3. Deploying a Tang server with SELinux in enforcing mode

You can use a Tang server to automatically unlock LUKS-encrypted volumes on Clevis-enabled clients. In the minimalistic scenario, you deploy a Tang server on port 80 by installing the tang package and entering the systemctl enable tangd.socket --now command. The following example procedure demonstrates the deployment of a Tang server running on a custom port as a confined service in SELinux enforcing mode.

Prerequisites

  • The policycoreutils-python-utils package and its dependencies are installed.
  • The firewalld service is running.

Procedure

  1. To install the tang package and its dependencies, enter the following command as root:

    # dnf install tang
  2. Pick an unoccupied port, for example, 7500/tcp, and allow the tangd service to bind to that port:

    # semanage port -a -t tangd_port_t -p tcp 7500

    Note that a port can be used only by one service at a time, and thus an attempt to use an already occupied port implies the ValueError: Port already defined error message.

  3. Open the port in the firewall:

    # firewall-cmd --add-port=7500/tcp
    # firewall-cmd --runtime-to-permanent
  4. Enable the tangd service:

    # systemctl enable tangd.socket
  5. Create an override file:

    # systemctl edit tangd.socket
  6. In the following editor screen, which opens an empty override.conf file located in the /etc/systemd/system/tangd.socket.d/ directory, change the default port for the Tang server from 80 to the previously picked number by adding the following lines:

    [Socket]
    ListenStream=
    ListenStream=7500
    Important

    Insert the previous code snippet between the lines starting with # Anything between here and # Lines below this, otherwise the system discards your changes.

  7. Save the changes by pressing Ctrl+O and Enter. Exit the editor by pressing Ctrl+X.
  8. Reload the changed configuration:

    # systemctl daemon-reload
  9. Check that your configuration is working:

    # systemctl show tangd.socket -p Listen
    Listen=[::]:7500 (Stream)
  10. Start the tangd service:

    # systemctl restart tangd.socket

    Because tangd uses the systemd socket activation mechanism, the server starts as soon as the first connection comes in. A new set of cryptographic keys is automatically generated at the first start. To perform cryptographic operations such as manual key generation, use the jose utility.

Additional resources

  • tang(8), semanage(8), firewall-cmd(1), jose(1), systemd.unit(5), and systemd.socket(5) man pages.

10.4. Rotating Tang server keys and updating bindings on clients

For security reasons, rotate your Tang server keys and update existing bindings on clients periodically. The precise interval at which you should rotate them depends on your application, key sizes, and institutional policy.

Alternatively, you can rotate Tang keys by using the nbde_server RHEL system role. See Using the nbde_server system role for setting up multiple Tang servers for more information.

Prerequisites

  • A Tang server is running.
  • The clevis and clevis-luks packages are installed on your clients.

Procedure

  1. Rename all keys in the /var/db/tang key database directory to have a leading . to hide them from advertisement. Note that the file names in the following example differs from unique file names in the key database directory of your Tang server:

    # cd /var/db/tang
    # ls -l
    -rw-r--r--. 1 root root 349 Feb  7 14:55 UV6dqXSwe1bRKG3KbJmdiR020hY.jwk
    -rw-r--r--. 1 root root 354 Feb  7 14:55 y9hxLTQSiSB5jSEGWnjhY8fDTJU.jwk
    # mv UV6dqXSwe1bRKG3KbJmdiR020hY.jwk .UV6dqXSwe1bRKG3KbJmdiR020hY.jwk
    # mv y9hxLTQSiSB5jSEGWnjhY8fDTJU.jwk .y9hxLTQSiSB5jSEGWnjhY8fDTJU.jwk
  2. Check that you renamed and therefore hid all keys from the Tang server advertisement:

    # ls -l
    total 0
  3. Generate new keys using the /usr/libexec/tangd-keygen command in /var/db/tang on the Tang server:

    # /usr/libexec/tangd-keygen /var/db/tang
    # ls /var/db/tang
    3ZWS6-cDrCG61UPJS2BMmPU4I54.jwk zyLuX6hijUy_PSeUEFDi7hi38.jwk
  4. Check that your Tang server advertises the signing key from the new key pair, for example:

    # tang-show-keys 7500
    3ZWS6-cDrCG61UPJS2BMmPU4I54
  5. On your NBDE clients, use the clevis luks report command to check if the keys advertised by the Tang server remains the same. You can identify slots with the relevant binding using the clevis luks list command, for example:

    # clevis luks list -d /dev/sda2
    1: tang '{"url":"http://tang.srv"}'
    # clevis luks report -d /dev/sda2 -s 1
    ...
    Report detected that some keys were rotated.
    Do you want to regenerate luks metadata with "clevis luks regen -d /dev/sda2 -s 1"? [ynYN]
  6. To regenerate LUKS metadata for the new keys either press y to the prompt of the previous command, or use the clevis luks regen command:

    # clevis luks regen -d /dev/sda2 -s 1
  7. When you are sure that all old clients use the new keys, you can remove the old keys from the Tang server, for example:

    # cd /var/db/tang
    # rm .*.jwk
Warning

Removing the old keys while clients are still using them can result in data loss. If you accidentally remove such keys, use the clevis luks regen command on the clients, and provide your LUKS password manually.

Additional resources

  • tang-show-keys(1), clevis-luks-list(1), clevis-luks-report(1), and clevis-luks-regen(1) man pages

10.5. Configuring automated unlocking by using a Tang key in the web console

You can configure automated unlocking of a LUKS-encrypted storage device using a key provided by a Tang server.

Prerequisites

Procedure

  1. Open the RHEL web console by entering the following address in a web browser:

    https://<localhost>:9090

    Replace the <localhost> part by the remote server’s hostname or IP address when you connect to a remote system.

  2. Provide your credentials and click Storage. In the Storage table, click the disk that contains an encrypted volume you plan to add to unlock automatically.
  3. In the following page with details of the selected disk, click + in the Keys section to add a Tang key:

    RHEL web console: Encryption
  4. Select Tang keyserver as Key source, provide the address of your Tang server, and a password that unlocks the LUKS-encrypted device. Click Add to confirm:

    RHEL web console: Add Tang key

    The following dialog window provides a command to verify that the key hash matches.

  5. In a terminal on the Tang server, use the tang-show-keys command to display the key hash for comparison. In this example, the Tang server is running on the port 7500:

    # tang-show-keys 7500
    x100_1k6GPiDOaMlL3WbpCjHOy9ul1bSfdhI3M08wO0
  6. Click Trust key when the key hashes in the web console and in the output of previously listed commands are the same:

    RHEL web console: Verify Tang key
  7. In RHEL 9.2 and later, after you select an encrypted root file system and a Tang server, you can skip adding the rd.neednet=1 parameter to the kernel command line, installing the clevis-dracut package, and regenerating an initial RAM disk (initrd). For non-root file systems, the web console now enables the remote-cryptsetup.target and clevis-luks-akspass.path systemd units, installs the clevis-systemd package, and adds the _netdev parameter to the fstab and crypttab configuration files.

Verification

  1. Check that the newly added Tang key is now listed in the Keys section with the Keyserver type:

    RHEL web console: A keyserver key is listed
  2. Verify that the bindings are available for the early boot, for example:

    # lsinitrd | grep clevis-luks
    lrwxrwxrwx   1 root     root           48 Jan  4 02:56 etc/systemd/system/cryptsetup.target.wants/clevis-luks-askpass.path -> /usr/lib/systemd/system/clevis-luks-askpass.path
    …

10.6. Basic NBDE and TPM2 encryption-client operations

The Clevis framework can encrypt plain-text files and decrypt both ciphertexts in the JSON Web Encryption (JWE) format and LUKS-encrypted block devices. Clevis clients can use either Tang network servers or Trusted Platform Module 2.0 (TPM 2.0) chips for cryptographic operations.

The following commands demonstrate the basic functionality provided by Clevis on examples containing plain-text files. You can also use them for troubleshooting your NBDE or Clevis+TPM deployments.

Encryption client bound to a Tang server

  • To check that a Clevis encryption client binds to a Tang server, use the clevis encrypt tang sub-command:

    $ clevis encrypt tang '{"url":"http://tang.srv:port"}' < input-plain.txt > secret.jwe
    The advertisement contains the following signing keys:
    
    _OsIk0T-E2l6qjfdDiwVmidoZjA
    
    Do you wish to trust these keys? [ynYN] y

    Change the http://tang.srv:port URL in the previous example to match the URL of the server where tang is installed. The secret.jwe output file contains your encrypted cipher text in the JWE format. This cipher text is read from the input-plain.txt input file.

    Alternatively, if your configuration requires a non-interactive communication with a Tang server without SSH access, you can download an advertisement and save it to a file:

    $ curl -sfg http://tang.srv:port/adv -o adv.jws

    Use the advertisement in the adv.jws file for any following tasks, such as encryption of files or messages:

    $ echo 'hello' | clevis encrypt tang '{"url":"http://tang.srv:port","adv":"adv.jws"}'
  • To decrypt data, use the clevis decrypt command and provide the cipher text (JWE):

    $ clevis decrypt < secret.jwe > output-plain.txt

Encryption client using TPM 2.0

  • To encrypt using a TPM 2.0 chip, use the clevis encrypt tpm2 sub-command with the only argument in form of the JSON configuration object:

    $ clevis encrypt tpm2 '{}' < input-plain.txt > secret.jwe

    To choose a different hierarchy, hash, and key algorithms, specify configuration properties, for example:

    $ clevis encrypt tpm2 '{"hash":"sha256","key":"rsa"}' < input-plain.txt > secret.jwe
  • To decrypt the data, provide the ciphertext in the JSON Web Encryption (JWE) format:

    $ clevis decrypt < secret.jwe > output-plain.txt

The pin also supports sealing data to a Platform Configuration Registers (PCR) state. That way, the data can only be unsealed if the PCR hashes values match the policy used when sealing.

For example, to seal the data to the PCR with index 0 and 7 for the SHA-256 bank:

$ clevis encrypt tpm2 '{"pcr_bank":"sha256","pcr_ids":"0,7"}' < input-plain.txt > secret.jwe
Warning

Hashes in PCRs can be rewritten, and you no longer can unlock your encrypted volume. For this reason, add a strong passphrase that enable you to unlock the encrypted volume manually even when a value in a PCR changes.

If the system cannot automatically unlock your encrypted volume after an upgrade of the shim-x64 package, follow the steps in the Clevis TPM2 no longer decrypts LUKS devices after a restart KCS article.

Additional resources

  • clevis-encrypt-tang(1), clevis-luks-unlockers(7), clevis(1), and clevis-encrypt-tpm2(1) man pages
  • clevis, clevis decrypt, and clevis encrypt tang commands without any arguments show the built-in CLI help, for example:

    $ clevis encrypt tang
    Usage: clevis encrypt tang CONFIG < PLAINTEXT > JWE
    ...

10.7. Configuring manual enrollment of LUKS-encrypted volumes

With the Clevis framework, you can configure clients for automated unlocking of LUKS-encrypted volumes when a selected Tang server is available. This creates an NBDE (Network-Bound Disk Encryption) deployment.

Prerequisites

  • A Tang server is running and available.

Procedure

  1. To automatically unlock an existing LUKS-encrypted volume, install the clevis-luks subpackage:

    # dnf install clevis-luks
  2. Identify the LUKS-encrypted volume for PBD. In the following example, the block device is referred as /dev/sda2:

    # lsblk
    NAME                                          MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
    sda                                             8:0    0    12G  0 disk
    ├─sda1                                          8:1    0     1G  0 part  /boot
    └─sda2                                          8:2    0    11G  0 part
      └─luks-40e20552-2ade-4954-9d56-565aa7994fb6 253:0    0    11G  0 crypt
        ├─rhel-root                               253:0    0   9.8G  0 lvm   /
        └─rhel-swap                               253:1    0   1.2G  0 lvm   [SWAP]
  3. Bind the volume to a Tang server using the clevis luks bind command:

    # clevis luks bind -d /dev/sda2 tang '{"url":"http://tang.srv"}'
    The advertisement contains the following signing keys:
    
    _OsIk0T-E2l6qjfdDiwVmidoZjA
    
    Do you wish to trust these keys? [ynYN] y
    You are about to initialize a LUKS device for metadata storage.
    Attempting to initialize it may result in data loss if data was
    already written into the LUKS header gap in a different format.
    A backup is advised before initialization is performed.
    
    Do you wish to initialize /dev/sda2? [yn] y
    Enter existing LUKS password:

    This command performs four steps:

    1. Creates a new key with the same entropy as the LUKS master key.
    2. Encrypts the new key with Clevis.
    3. Stores the Clevis JWE object in the LUKS2 header token or uses LUKSMeta if the non-default LUKS1 header is used.
    4. Enables the new key for use with LUKS.
    Note

    The binding procedure assumes that there is at least one free LUKS password slot. The clevis luks bind command takes one of the slots.

    The volume can now be unlocked with your existing password as well as with the Clevis policy.

  4. To enable the early boot system to process the disk binding, use the dracut tool on an already installed system:

    # dnf install clevis-dracut

    In RHEL, Clevis produces a generic initrd (initial RAM disk) without host-specific configuration options and does not automatically add parameters such as rd.neednet=1 to the kernel command line. If your configuration relies on a Tang pin that requires network during early boot, use the --hostonly-cmdline argument and dracut adds rd.neednet=1 when it detects a Tang binding:

    # dracut -fv --regenerate-all --hostonly-cmdline

    Alternatively, create a .conf file in the /etc/dracut.conf.d/, and add the hostonly_cmdline=yes option to the file, for example:

    # echo "hostonly_cmdline=yes" > /etc/dracut.conf.d/clevis.conf
    Note

    You can also ensure that networking for a Tang pin is available during early boot by using the grubby tool on the system where Clevis is installed:

    # grubby --update-kernel=ALL --args="rd.neednet=1"

    Then you can use dracut without --hostonly-cmdline:

    # dracut -fv --regenerate-all

Verification

  1. To verify that the Clevis JWE object is successfully placed in a LUKS header, use the clevis luks list command:

    # clevis luks list -d /dev/sda2
    1: tang '{"url":"http://tang.srv:port"}'
Important

To use NBDE for clients with static IP configuration (without DHCP), pass your network configuration to the dracut tool manually, for example:

# dracut -fv --regenerate-all --kernel-cmdline "ip=192.0.2.10::192.0.2.1:255.255.255.0::ens3:none nameserver=192.0.2.100"

Alternatively, create a .conf file in the /etc/dracut.conf.d/ directory with the static network information. For example:

# cat /etc/dracut.conf.d/static_ip.conf
kernel_cmdline="ip=192.0.2.10::192.0.2.1:255.255.255.0::ens3:none nameserver=192.0.2.100"

Regenerate the initial RAM disk image:

# dracut -fv --regenerate-all

Additional resources

10.8. Configuring manual enrollment of LUKS-encrypted volumes by using a TPM 2.0 policy

You can configure unlocking of LUKS-encrypted volumes by using a Trusted Platform Module 2.0 (TPM 2.0) policy.

Prerequisites

  • An accessible TPM 2.0-compatible device.
  • A system with the 64-bit Intel or 64-bit AMD architecture.

Procedure

  1. To automatically unlock an existing LUKS-encrypted volume, install the clevis-luks subpackage:

    # dnf install clevis-luks
  2. Identify the LUKS-encrypted volume for PBD. In the following example, the block device is referred as /dev/sda2:

    # lsblk
    NAME                                          MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
    sda                                             8:0    0    12G  0 disk
    ├─sda1                                          8:1    0     1G  0 part  /boot
    └─sda2                                          8:2    0    11G  0 part
      └─luks-40e20552-2ade-4954-9d56-565aa7994fb6 253:0    0    11G  0 crypt
        ├─rhel-root                               253:0    0   9.8G  0 lvm   /
        └─rhel-swap                               253:1    0   1.2G  0 lvm   [SWAP]
  3. Bind the volume to a TPM 2.0 device using the clevis luks bind command, for example:

    # clevis luks bind -d /dev/sda2 tpm2 '{"hash":"sha256","key":"rsa"}'
    ...
    Do you wish to initialize /dev/sda2? [yn] y
    Enter existing LUKS password:

    This command performs four steps:

    1. Creates a new key with the same entropy as the LUKS master key.
    2. Encrypts the new key with Clevis.
    3. Stores the Clevis JWE object in the LUKS2 header token or uses LUKSMeta if the non-default LUKS1 header is used.
    4. Enables the new key for use with LUKS.

      Note

      The binding procedure assumes that there is at least one free LUKS password slot. The clevis luks bind command takes one of the slots.

      Alternatively, if you want to seal data to specific Platform Configuration Registers (PCR) states, add the pcr_bank and pcr_ids values to the clevis luks bind command, for example:

      # clevis luks bind -d /dev/sda2 tpm2 '{"hash":"sha256","key":"rsa","pcr_bank":"sha256","pcr_ids":"0,1"}'
      Important

      Because the data can only be unsealed if PCR hashes values match the policy used when sealing and the hashes can be rewritten, add a strong passphrase that enable you to unlock the encrypted volume manually when a value in a PCR changes.

      If the system cannot automatically unlock your encrypted volume after an upgrade of the shim-x64 package, follow the steps in the Clevis TPM2 no longer decrypts LUKS devices after a restart KCS article.

  4. The volume can now be unlocked with your existing password as well as with the Clevis policy.
  5. To enable the early boot system to process the disk binding, use the dracut tool on an already installed system:

    # dnf install clevis-dracut
    # dracut -fv --regenerate-all

Verification

  1. To verify that the Clevis JWE object is successfully placed in a LUKS header, use the clevis luks list command:

    # clevis luks list -d /dev/sda2
    1: tpm2 '{"hash":"sha256","key":"rsa"}'

Additional resources

  • clevis-luks-bind(1), clevis-encrypt-tpm2(1), and dracut.cmdline(7) man pages on your system

10.9. Removing a Clevis pin from a LUKS-encrypted volume manually

Use the following procedure for manual removing the metadata created by the clevis luks bind command and also for wiping a key slot that contains passphrase added by Clevis.

Important

The recommended way to remove a Clevis pin from a LUKS-encrypted volume is through the clevis luks unbind command. The removal procedure using clevis luks unbind consists of only one step and works for both LUKS1 and LUKS2 volumes. The following example command removes the metadata created by the binding step and wipe the key slot 1 on the /dev/sda2 device:

# clevis luks unbind -d /dev/sda2 -s 1

Prerequisites

  • A LUKS-encrypted volume with a Clevis binding.

Procedure

  1. Check which LUKS version the volume, for example /dev/sda2, is encrypted by and identify a slot and a token that is bound to Clevis:

    # cryptsetup luksDump /dev/sda2
    LUKS header information
    Version:        2
    ...
    Keyslots:
      0: luks2
    ...
    1: luks2
          Key:        512 bits
          Priority:   normal
          Cipher:     aes-xts-plain64
    ...
          Tokens:
            0: clevis
                  Keyslot:  1
    ...

    In the previous example, the Clevis token is identified by 0 and the associated key slot is 1.

  2. In case of LUKS2 encryption, remove the token:

    # cryptsetup token remove --token-id 0 /dev/sda2
  3. If your device is encrypted by LUKS1, which is indicated by the Version: 1 string in the output of the cryptsetup luksDump command, perform this additional step with the luksmeta wipe command:

    # luksmeta wipe -d /dev/sda2 -s 1
  4. Wipe the key slot containing the Clevis passphrase:

    # cryptsetup luksKillSlot /dev/sda2 1

Additional resources

  • clevis-luks-unbind(1), cryptsetup(8), and luksmeta(8) man pages

10.10. Configuring automated enrollment of LUKS-encrypted volumes by using Kickstart

Follow the steps in this procedure to configure an automated installation process that uses Clevis for the enrollment of LUKS-encrypted volumes.

Procedure

  1. Instruct Kickstart to partition the disk such that LUKS encryption has enabled for all mount points, other than /boot, with a temporary password. The password is temporary for this step of the enrollment process.

    part /boot --fstype="xfs" --ondisk=vda --size=256
    part / --fstype="xfs" --ondisk=vda --grow --encrypted --passphrase=temppass

    Note that OSPP-compliant systems require a more complex configuration, for example:

    part /boot --fstype="xfs" --ondisk=vda --size=256
    part / --fstype="xfs" --ondisk=vda --size=2048 --encrypted --passphrase=temppass
    part /var --fstype="xfs" --ondisk=vda --size=1024 --encrypted --passphrase=temppass
    part /tmp --fstype="xfs" --ondisk=vda --size=1024 --encrypted --passphrase=temppass
    part /home --fstype="xfs" --ondisk=vda --size=2048 --grow --encrypted --passphrase=temppass
    part /var/log --fstype="xfs" --ondisk=vda --size=1024 --encrypted --passphrase=temppass
    part /var/log/audit --fstype="xfs" --ondisk=vda --size=1024 --encrypted --passphrase=temppass
  2. Install the related Clevis packages by listing them in the %packages section:

    %packages
    clevis-dracut
    clevis-luks
    clevis-systemd
    %end
  3. Optionally, to ensure that you can unlock the encrypted volume manually when required, add a strong passphrase before you remove the temporary passphrase. See the How to add a passphrase, key, or keyfile to an existing LUKS device article for more information.
  4. Call clevis luks bind to perform binding in the %post section. Afterward, remove the temporary password:

    %post
    clevis luks bind -y -k - -d /dev/vda2 \
    tang '{"url":"http://tang.srv"}' <<< "temppass"
    cryptsetup luksRemoveKey /dev/vda2 <<< "temppass"
    dracut -fv --regenerate-all
    %end

    If your configuration relies on a Tang pin that requires network during early boot or you use NBDE clients with static IP configurations, you have to modify the dracut command as described in Configuring manual enrollment of LUKS-encrypted volumes.

    Note that the -y option for the clevis luks bind command is available from RHEL 8.3. In RHEL 8.2 and older, replace -y by -f in the clevis luks bind command and download the advertisement from the Tang server:

    %post
    curl -sfg http://tang.srv/adv -o adv.jws
    clevis luks bind -f -k - -d /dev/vda2 \
    tang '{"url":"http://tang.srv","adv":"adv.jws"}' <<< "temppass"
    cryptsetup luksRemoveKey /dev/vda2 <<< "temppass"
    dracut -fv --regenerate-all
    %end
    Warning

    The cryptsetup luksRemoveKey command prevents any further administration of a LUKS2 device on which you apply it. You can recover a removed master key using the dmsetup command only for LUKS1 devices.

You can use an analogous procedure when using a TPM 2.0 policy instead of a Tang server.

Additional resources

10.11. Configuring automated unlocking of a LUKS-encrypted removable storage device

You can set up an automated unlocking process of a LUKS-encrypted USB storage device.

Procedure

  1. To automatically unlock a LUKS-encrypted removable storage device, such as a USB drive, install the clevis-udisks2 package:

    # dnf install clevis-udisks2
  2. Reboot the system, and then perform the binding step using the clevis luks bind command as described in Configuring manual enrollment of LUKS-encrypted volumes, for example:

    # clevis luks bind -d /dev/sdb1 tang '{"url":"http://tang.srv"}'
  3. The LUKS-encrypted removable device can be now unlocked automatically in your GNOME desktop session. The device bound to a Clevis policy can be also unlocked by the clevis luks unlock command:

    # clevis luks unlock -d /dev/sdb1

You can use an analogous procedure when using a TPM 2.0 policy instead of a Tang server.

Additional resources

  • clevis-luks-unlockers(7) man page

10.12. Deploying high-availability NBDE systems

Tang provides two methods for building a high-availability deployment:

Client redundancy (recommended)
Clients should be configured with the ability to bind to multiple Tang servers. In this setup, each Tang server has its own keys and clients can decrypt by contacting a subset of these servers. Clevis already supports this workflow through its sss plug-in. Red Hat recommends this method for a high-availability deployment.
Key sharing
For redundancy purposes, more than one instance of Tang can be deployed. To set up a second or any subsequent instance, install the tang packages and copy the key directory to the new host using rsync over SSH. Note that Red Hat does not recommend this method because sharing keys increases the risk of key compromise and requires additional automation infrastructure.
High-available NBDE using Shamir’s Secret Sharing

Shamir’s Secret Sharing (SSS) is a cryptographic scheme that divides a secret into several unique parts. To reconstruct the secret, a number of parts is required. The number is called threshold and SSS is also referred to as a thresholding scheme.

Clevis provides an implementation of SSS. It creates a key and divides it into a number of pieces. Each piece is encrypted using another pin including even SSS recursively. Additionally, you define the threshold t. If an NBDE deployment decrypts at least t pieces, then it recovers the encryption key and the decryption process succeeds. When Clevis detects a smaller number of parts than specified in the threshold, it prints an error message.

Example 1: Redundancy with two Tang servers

The following command decrypts a LUKS-encrypted device when at least one of two Tang servers is available:

# clevis luks bind -d /dev/sda1 sss '{"t":1,"pins":{"tang":[{"url":"http://tang1.srv"},{"url":"http://tang2.srv"}]}}'

The previous command used the following configuration scheme:

{
    "t":1,
    "pins":{
        "tang":[
            {
                "url":"http://tang1.srv"
            },
            {
                "url":"http://tang2.srv"
            }
        ]
    }
}

In this configuration, the SSS threshold t is set to 1 and the clevis luks bind command successfully reconstructs the secret if at least one from two listed tang servers is available.

Example 2: Shared secret on a Tang server and a TPM device

The following command successfully decrypts a LUKS-encrypted device when both the tang server and the tpm2 device are available:

# clevis luks bind -d /dev/sda1 sss '{"t":2,"pins":{"tang":[{"url":"http://tang1.srv"}], "tpm2": {"pcr_ids":"0,7"}}}'

The configuration scheme with the SSS threshold 't' set to '2' is now:

{
    "t":2,
    "pins":{
        "tang":[
            {
                "url":"http://tang1.srv"
            }
        ],
        "tpm2":{
            "pcr_ids":"0,7"
        }
    }
}

Additional resources

  • tang(8) (section High Availability), clevis(1) (section Shamir’s Secret Sharing), and clevis-encrypt-sss(1) man pages

10.13. Deployment of virtual machines in a NBDE network

The clevis luks bind command does not change the LUKS master key. This implies that if you create a LUKS-encrypted image for use in a virtual machine or cloud environment, all the instances that run this image share a master key. This is extremely insecure and should be avoided at all times.

This is not a limitation of Clevis but a design principle of LUKS. If your scenario requires having encrypted root volumes in a cloud, perform the installation process (usually using Kickstart) for each instance of Red Hat Enterprise Linux in the cloud as well. The images cannot be shared without also sharing a LUKS master key.

To deploy automated unlocking in a virtualized environment, use systems such as lorax or virt-install together with a Kickstart file (see Configuring automated enrollment of LUKS-encrypted volumes using Kickstart) or another automated provisioning tool to ensure that each encrypted VM has a unique master key.

Additional resources

  • clevis-luks-bind(1) man page

10.14. Building automatically-enrollable VM images for cloud environments by using NBDE

Deploying automatically-enrollable encrypted images in a cloud environment can provide a unique set of challenges. Like other virtualization environments, it is recommended to reduce the number of instances started from a single image to avoid sharing the LUKS master key.

Therefore, the best practice is to create customized images that are not shared in any public repository and that provide a base for the deployment of a limited amount of instances. The exact number of instances to create should be defined by deployment’s security policies and based on the risk tolerance associated with the LUKS master key attack vector.

To build LUKS-enabled automated deployments, systems such as Lorax or virt-install together with a Kickstart file should be used to ensure master key uniqueness during the image building process.

Cloud environments enable two Tang server deployment options which we consider here. First, the Tang server can be deployed within the cloud environment itself. Second, the Tang server can be deployed outside of the cloud on independent infrastructure with a VPN link between the two infrastructures.

Deploying Tang natively in the cloud does allow for easy deployment. However, given that it shares infrastructure with the data persistence layer of ciphertext of other systems, it may be possible for both the Tang server’s private key and the Clevis metadata to be stored on the same physical disk. Access to this physical disk permits a full compromise of the ciphertext data.

Important

Always maintain a physical separation between the location where the data is stored and the system where Tang is running. This separation between the cloud and the Tang server ensures that the Tang server’s private key cannot be accidentally combined with the Clevis metadata. It also provides local control of the Tang server if the cloud infrastructure is at risk.

10.15. Deploying Tang as a container

The tang container image provides Tang-server decryption capabilities for Clevis clients that run either in OpenShift Container Platform (OCP) clusters or in separate virtual machines.

Prerequisites

  • The podman package and its dependencies are installed on the system.
  • You have logged in on the registry.redhat.io container catalog using the podman login registry.redhat.io command. See Red Hat Container Registry Authentication for more information.
  • The Clevis client is installed on systems containing LUKS-encrypted volumes that you want to automatically unlock by using a Tang server.

Procedure

  1. Pull the tang container image from the registry.redhat.io registry:

    # podman pull registry.redhat.io/rhel9/tang
  2. Run the container, specify its port, and specify the path to the Tang keys. The previous example runs the tang container, specifies the port 7500, and indicates a path to the Tang keys of the /var/db/tang directory:

    # podman run -d -p 7500:7500 -v tang-keys:/var/db/tang --name tang registry.redhat.io/rhel9/tang

    Note that Tang uses port 80 by default but this may collide with other services such as the Apache HTTP server.

  3. [Optional] For increased security, rotate the Tang keys periodically. You can use the tangd-rotate-keys script, for example:

    # podman run --rm -v tang-keys:/var/db/tang registry.redhat.io/rhel9/tang tangd-rotate-keys -v -d /var/db/tang
    Rotated key 'rZAMKAseaXBe0rcKXL1hCCIq-DY.jwk' -> .'rZAMKAseaXBe0rcKXL1hCCIq-DY.jwk'
    Rotated key 'x1AIpc6WmnCU-CabD8_4q18vDuw.jwk' -> .'x1AIpc6WmnCU-CabD8_4q18vDuw.jwk'
    Created new key GrMMX_WfdqomIU_4RyjpcdlXb0E.jwk
    Created new key _dTTfn17sZZqVAp80u3ygFDHtjk.jwk
    Keys rotated successfully.

Verification

  • On a system that contains LUKS-encrypted volumes for automated unlocking by the presence of the Tang server, check that the Clevis client can encrypt and decrypt a plain-text message using Tang:

    # echo test | clevis encrypt tang '{"url":"http://localhost:7500"}' | clevis decrypt
    The advertisement contains the following signing keys:
    
    x1AIpc6WmnCU-CabD8_4q18vDuw
    
    Do you wish to trust these keys? [ynYN] y
    test

    The previous example command shows the test string at the end of its output when a Tang server is available on the localhost URL and communicates through port 7500.

Additional resources

  • podman(1), clevis(1), and tang(8) man pages

10.16. Introduction to the nbde_client and nbde_server RHEL system roles (Clevis and Tang)

RHEL system roles is a collection of Ansible roles and modules that provide a consistent configuration interface to remotely manage multiple RHEL systems.

You can use Ansible roles for automated deployments of Policy-Based Decryption (PBD) solutions using Clevis and Tang. The rhel-system-roles package contains these system roles, the related examples, and also the reference documentation.

The nbde_client system role enables you to deploy multiple Clevis clients in an automated way. Note that the nbde_client role supports only Tang bindings, and you cannot use it for TPM2 bindings at the moment.

The nbde_client role requires volumes that are already encrypted using LUKS. This role supports to bind a LUKS-encrypted volume to one or more Network-Bound (NBDE) servers - Tang servers. You can either preserve the existing volume encryption with a passphrase or remove it. After removing the passphrase, you can unlock the volume only using NBDE. This is useful when a volume is initially encrypted using a temporary key or password that you should remove after you provision the system.

If you provide both a passphrase and a key file, the role uses what you have provided first. If it does not find any of these valid, it attempts to retrieve a passphrase from an existing binding.

PBD defines a binding as a mapping of a device to a slot. This means that you can have multiple bindings for the same device. The default slot is slot 1.

The nbde_client role provides also the state variable. Use the present value for either creating a new binding or updating an existing one. Contrary to a clevis luks bind command, you can use state: present also for overwriting an existing binding in its device slot. The absent value removes a specified binding.

Using the nbde_client system role, you can deploy and manage a Tang server as part of an automated disk encryption solution. This role supports the following features:

  • Rotating Tang keys
  • Deploying and backing up Tang keys

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.nbde_server/README.md file
  • /usr/share/ansible/roles/rhel-system-roles.nbde_client/README.md file
  • /usr/share/doc/rhel-system-roles/nbde_server/ directory
  • /usr/share/doc/rhel-system-roles/nbde_client/ directory

10.17. Using the nbde_server RHEL system role for setting up multiple Tang servers

You can prepare and apply an Ansible playbook containing your Tang server settings.

Prerequisites

Procedure

  1. Create a playbook file, for example ~/playbook.yml, with the following content:

    ---
    - hosts: managed-node-01.example.com
      roles:
        - rhel-system-roles.nbde_server
      vars:
        nbde_server_rotate_keys: yes
        nbde_server_manage_firewall: true
        nbde_server_manage_selinux: true

    This example playbook ensures deploying of your Tang server and a key rotation.

    When nbde_server_manage_firewall and nbde_server_manage_selinux are both set to true, the nbde_server role uses the firewall and selinux roles to manage the ports used by the nbde_server role.

  2. Validate the playbook syntax:

    $ ansible-playbook --syntax-check ~/playbook.yml

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    $ ansible-playbook ~/playbook.yml

Verification

  • To ensure that networking for a Tang pin is available during early boot by using the grubby tool on the systems where Clevis is installed, enter:

    # grubby --update-kernel=ALL --args="rd.neednet=1"

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.nbde_server/README.md file
  • /usr/share/doc/rhel-system-roles/nbde_server/ directory

10.18. Setting up multiple Clevis clients by using the nbde_client RHEL system role

With the nbde_client RHEL system role, you can prepare and apply an Ansible playbook that contains your Clevis client settings on multiple systems.

Note

The nbde_client system role supports only Tang bindings. Therefore, you cannot use it for TPM2 bindings.

Prerequisites

Procedure

  1. Create a playbook file, for example ~/playbook.yml, with the following content:

    - hosts: managed-node-01.example.com
      roles:
        - rhel-system-roles.nbde_client
      vars:
        nbde_client_bindings:
          - device: /dev/rhel/root
            encryption_key_src: /etc/luks/keyfile
            servers:
              - http://server1.example.com
              - http://server2.example.com
          - device: /dev/rhel/swap
            encryption_key_src: /etc/luks/keyfile
            servers:
              - http://server1.example.com
              - http://server2.example.com

    This example playbook configures Clevis clients for automated unlocking of two LUKS-encrypted volumes when at least one of two Tang servers is available

    The nbde_client system role supports only scenarios with Dynamic Host Configuration Protocol (DHCP). To use NBDE for clients with static IP configuration use the following playbook:

    - hosts: managed-node-01.example.com
      roles:
        - rhel-system-roles.nbde_client
      vars:
        nbde_client_bindings:
          - device: /dev/rhel/root
            encryption_key_src: /etc/luks/keyfile
            servers:
              - http://server1.example.com
              - http://server2.example.com
          - device: /dev/rhel/swap
            encryption_key_src: /etc/luks/keyfile
            servers:
              - http://server1.example.com
              - http://server2.example.com
      tasks:
        - name: Configure a client with a static IP address during early boot
          ansible.builtin.command:
            cmd: grubby --update-kernel=ALL --args='GRUB_CMDLINE_LINUX_DEFAULT="ip={{ <ansible_default_ipv4.address> }}::{{ <ansible_default_ipv4.gateway> }}:{{ <ansible_default_ipv4.netmask> }}::{{ <ansible_default_ipv4.alias> }}:none"'

    In this playbook, replace the <ansible_default_ipv4.*> strings with IP addresses of your network, for example: ip={{ 192.0.2.10 }}::{{ 192.0.2.1 }}:{{ 255.255.255.0 }}::{{ ens3 }}:none.

  2. Validate the playbook syntax:

    $ ansible-playbook --syntax-check ~/playbook.yml

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    $ ansible-playbook ~/playbook.yml

Additional resources

Chapter 11. Auditing the system

Audit does not provide additional security to your system; rather, it can be used to discover violations of security policies used on your system. These violations can further be prevented by additional security measures such as SELinux.

11.1. Linux Audit

The Linux Audit system provides a way to track security-relevant information about your system. Based on pre-configured rules, Audit generates log entries to record as much information about the events that are happening on your system as possible. This information is crucial for mission-critical environments to determine the violator of the security policy and the actions they performed.

The following list summarizes some of the information that Audit is capable of recording in its log files:

  • Date and time, type, and outcome of an event
  • Sensitivity labels of subjects and objects
  • Association of an event with the identity of the user who triggered the event
  • All modifications to Audit configuration and attempts to access Audit log files
  • All uses of authentication mechanisms, such as SSH, Kerberos, and others
  • Changes to any trusted database, such as /etc/passwd
  • Attempts to import or export information into or from the system
  • Include or exclude events based on user identity, subject and object labels, and other attributes

The use of the Audit system is also a requirement for a number of security-related certifications. Audit is designed to meet or exceed the requirements of the following certifications or compliance guides:

  • Controlled Access Protection Profile (CAPP)
  • Labeled Security Protection Profile (LSPP)
  • Rule Set Base Access Control (RSBAC)
  • National Industrial Security Program Operating Manual (NISPOM)
  • Federal Information Security Management Act (FISMA)
  • Payment Card Industry — Data Security Standard (PCI-DSS)
  • Security Technical Implementation Guides (STIG)

Audit has also been:

  • Evaluated by National Information Assurance Partnership (NIAP) and Best Security Industries (BSI)
  • Certified to LSPP/CAPP/RSBAC/EAL4+ on Red Hat Enterprise Linux 5
  • Certified to Operating System Protection Profile / Evaluation Assurance Level 4+ (OSPP/EAL4+) on Red Hat Enterprise Linux 6

Use Cases

Watching file access
Audit can track whether a file or a directory has been accessed, modified, executed, or the file’s attributes have been changed. This is useful, for example, to detect access to important files and have an Audit trail available in case one of these files is corrupted.
Monitoring system calls
Audit can be configured to generate a log entry every time a particular system call is used. This can be used, for example, to track changes to the system time by monitoring the settimeofday, clock_adjtime, and other time-related system calls.
Recording commands run by a user
Audit can track whether a file has been executed, so rules can be defined to record every execution of a particular command. For example, a rule can be defined for every executable in the /bin directory. The resulting log entries can then be searched by user ID to generate an audit trail of executed commands per user.
Recording execution of system pathnames
Aside from watching file access which translates a path to an inode at rule invocation, Audit can now watch the execution of a path even if it does not exist at rule invocation, or if the file is replaced after rule invocation. This allows rules to continue to work after upgrading a program executable or before it is even installed.
Recording security events
The pam_faillock authentication module is capable of recording failed login attempts. Audit can be set up to record failed login attempts as well and provides additional information about the user who attempted to log in.
Searching for events
Audit provides the ausearch utility, which can be used to filter the log entries and provide a complete audit trail based on several conditions.
Running summary reports
The aureport utility can be used to generate, among other things, daily reports of recorded events. A system administrator can then analyze these reports and investigate suspicious activity further.
Monitoring network access
The nftables, iptables, and ebtables utilities can be configured to trigger Audit events, allowing system administrators to monitor network access.
Note

System performance may be affected depending on the amount of information that is collected by Audit.

11.2. Audit system architecture

The Audit system consists of two main parts: the user-space applications and utilities, and the kernel-side system call processing. The kernel component receives system calls from user-space applications and filters them through one of the following filters: user, task, fstype, or exit.

After a system call passes the exclude filter, it is sent through one of the aforementioned filters, which, based on the Audit rule configuration, sends it to the Audit daemon for further processing.

The user-space Audit daemon collects the information from the kernel and creates entries in a log file. Other Audit user-space utilities interact with the Audit daemon, the kernel Audit component, or the Audit log files:

  • The auditctl Audit control utility interacts with the kernel Audit component to manage rules and to control many settings and parameters of the event generation process.
  • The remaining Audit utilities take the contents of the Audit log files as input and generate output based on user’s requirements. For example, the aureport utility generates a report of all recorded events.

In RHEL 9, the Audit dispatcher daemon (audisp) functionality is integrated in the Audit daemon (auditd). Configuration files of plugins for the interaction of real-time analytical programs with Audit events are located in the /etc/audit/plugins.d/ directory by default.

11.3. Configuring auditd for a secure environment

The default auditd configuration should be suitable for most environments. However, if your environment must meet strict security policies, you can change the following settings for the Audit daemon configuration in the /etc/audit/auditd.conf file:

log_file
The directory that holds the Audit log files (usually /var/log/audit/) should reside on a separate mount point. This prevents other processes from consuming space in this directory and provides accurate detection of the remaining space for the Audit daemon.
max_log_file
Specifies the maximum size of a single Audit log file, must be set to make full use of the available space on the partition that holds the Audit log files. The max_log_file` parameter specifies the maximum file size in megabytes. The value given must be numeric.
max_log_file_action
Decides what action is taken once the limit set in max_log_file is reached, should be set to keep_logs to prevent Audit log files from being overwritten.
space_left
Specifies the amount of free space left on the disk for which an action that is set in the space_left_action parameter is triggered. Must be set to a number that gives the administrator enough time to respond and free up disk space. The space_left value depends on the rate at which the Audit log files are generated. If the value of space_left is specified as a whole number, it is interpreted as an absolute size in megabytes (MiB). If the value is specified as a number between 1 and 99 followed by a percentage sign (for example, 5%), the Audit daemon calculates the absolute size in megabytes based on the size of the file system containing log_file.
space_left_action
It is recommended to set the space_left_action parameter to email or exec with an appropriate notification method.
admin_space_left
Specifies the absolute minimum amount of free space for which an action that is set in the admin_space_left_action parameter is triggered, must be set to a value that leaves enough space to log actions performed by the administrator. The numeric value for this parameter should be lower than the number for space_left. You can also append a percent sign (for example, 1%) to the number to have the audit daemon calculate the number based on the disk partition size.
admin_space_left_action
Should be set to single to put the system into single-user mode and allow the administrator to free up some disk space.
disk_full_action
Specifies an action that is triggered when no free space is available on the partition that holds the Audit log files, must be set to halt or single. This ensures that the system is either shut down or operating in single-user mode when Audit can no longer log events.
disk_error_action
Specifies an action that is triggered in case an error is detected on the partition that holds the Audit log files, must be set to syslog, single, or halt, depending on your local security policies regarding the handling of hardware malfunctions.
flush
Should be set to incremental_async. It works in combination with the freq parameter, which determines how many records can be sent to the disk before forcing a hard synchronization with the hard drive. The freq parameter should be set to 100. These parameters assure that Audit event data is synchronized with the log files on the disk while keeping good performance for bursts of activity.

The remaining configuration options should be set according to your local security policy.

11.4. Starting and controlling auditd

After auditd is configured, start the service to collect Audit information and store it in the log files. Use the following command as the root user to start auditd:

service auditd start

To configure auditd to start at boot time:

systemctl enable auditd

You can temporarily disable auditd with the # auditctl -e 0 command and re-enable it with # auditctl -e 1.

You can perform other actions on auditd by using the service auditd <action> command, where <action> can be one of the following:

stop
Stops auditd.
restart
Restarts auditd.
reload or force-reload
Reloads the configuration of auditd from the /etc/audit/auditd.conf file.
rotate
Rotates the log files in the /var/log/audit/ directory.
resume
Resumes logging of Audit events after it has been previously suspended, for example, when there is not enough free space on the disk partition that holds the Audit log files.
condrestart or try-restart
Restarts auditd only if it is already running.
status
Displays the running status of auditd.
Note

The service command is the only way to correctly interact with the auditd daemon. You need to use the service command so that the auid value is properly recorded. You can use the systemctl command only for two actions: enable and status.

11.5. Understanding Audit log files

By default, the Audit system stores log entries in the /var/log/audit/audit.log file; if log rotation is enabled, rotated audit.log files are stored in the same directory.

Add the following Audit rule to log every attempt to read or modify the /etc/ssh/sshd_config file:

# auditctl -w /etc/ssh/sshd_config -p warx -k sshd_config

If the auditd daemon is running, for example, using the following command creates a new event in the Audit log file:

cat /etc/ssh/sshd_config

This event in the audit.log file looks as follows:

type=SYSCALL msg=audit(1364481363.243:24287): arch=c000003e syscall=2 success=no exit=-13 a0=7fffd19c5592 a1=0 a2=7fffd19c4b50 a3=a items=1 ppid=2686 pid=3538 auid=1000 uid=1000 gid=1000 euid=1000 suid=1000 fsuid=1000 egid=1000 sgid=1000 fsgid=1000 tty=pts0 ses=1 comm="cat" exe="/bin/cat" subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key="sshd_config"
type=CWD msg=audit(1364481363.243:24287):  cwd="/home/shadowman"
type=PATH msg=audit(1364481363.243:24287): item=0 name="/etc/ssh/sshd_config" inode=409248 dev=fd:00 mode=0100600 ouid=0 ogid=0 rdev=00:00 obj=system_u:object_r:etc_t:s0  nametype=NORMAL cap_fp=none cap_fi=none cap_fe=0 cap_fver=0
type=PROCTITLE msg=audit(1364481363.243:24287) : proctitle=636174002F6574632F7373682F737368645F636F6E666967

The above event consists of four records, which share the same time stamp and serial number. Records always start with the type= keyword. Each record consists of several name=value pairs separated by a white space or a comma. A detailed analysis of the above event follows:

First Record

type=SYSCALL
The type field contains the type of the record. In this example, the SYSCALL value specifies that this record was triggered by a system call to the kernel.
msg=audit(1364481363.243:24287):

The msg field records:

  • A time stamp and a unique ID of the record in the form audit(time_stamp:ID). Multiple records can share the same time stamp and ID if they were generated as part of the same Audit event. The time stamp is using the Unix time format - seconds since 00:00:00 UTC on 1 January 1970.
  • Various event-specific name=value pairs provided by the kernel or user-space applications.
arch=c000003e
The arch field contains information about the CPU architecture of the system. The value, c000003e, is encoded in hexadecimal notation. When searching Audit records with the ausearch command, use the -i or --interpret option to automatically convert hexadecimal values into their human-readable equivalents. The c000003e value is interpreted as x86_64.
syscall=2
The syscall field records the type of the system call that was sent to the kernel. The value, 2, can be matched with its human-readable equivalent in the /usr/include/asm/unistd_64.h file. In this case, 2 is the open system call. Note that the ausyscall utility allows you to convert system call numbers to their human-readable equivalents. Use the ausyscall --dump command to display a listing of all system calls along with their numbers. For more information, see the ausyscall(8) man page.
success=no
The success field records whether the system call recorded in that particular event succeeded or failed. In this case, the call did not succeed.
exit=-13

The exit field contains a value that specifies the exit code returned by the system call. This value varies for a different system call. You can interpret the value to its human-readable equivalent with the following command:

ausearch --interpret --exit -13

Note that the previous example assumes that your Audit log contains an event that failed with exit code -13.

a0=7fffd19c5592, a1=0, a2=7fffd19c5592, a3=a
The a0 to a3 fields record the first four arguments, encoded in hexadecimal notation, of the system call in this event. These arguments depend on the system call that is used; they can be interpreted by the ausearch utility.
items=1
The items field contains the number of PATH auxiliary records that follow the syscall record.
ppid=2686
The ppid field records the Parent Process ID (PPID). In this case, 2686 was the PPID of the parent process such as bash.
pid=3538
The pid field records the Process ID (PID). In this case, 3538 was the PID of the cat process.
auid=1000
The auid field records the Audit user ID, that is the loginuid. This ID is assigned to a user upon login and is inherited by every process even when the user’s identity changes, for example, by switching user accounts with the su - john command.
uid=1000
The uid field records the user ID of the user who started the analyzed process. The user ID can be interpreted into user names with the following command: ausearch -i --uid UID.
gid=1000
The gid field records the group ID of the user who started the analyzed process.
euid=1000
The euid field records the effective user ID of the user who started the analyzed process.
suid=1000
The suid field records the set user ID of the user who started the analyzed process.
fsuid=1000
The fsuid field records the file system user ID of the user who started the analyzed process.
egid=1000
The egid field records the effective group ID of the user who started the analyzed process.
sgid=1000
The sgid field records the set group ID of the user who started the analyzed process.
fsgid=1000
The fsgid field records the file system group ID of the user who started the analyzed process.
tty=pts0
The tty field records the terminal from which the analyzed process was invoked.
ses=1
The ses field records the session ID of the session from which the analyzed process was invoked.
comm="cat"
The comm field records the command-line name of the command that was used to invoke the analyzed process. In this case, the cat command was used to trigger this Audit event.
exe="/bin/cat"
The exe field records the path to the executable that was used to invoke the analyzed process.
subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
The subj field records the SELinux context with which the analyzed process was labeled at the time of execution.
key="sshd_config"
The key field records the administrator-defined string associated with the rule that generated this event in the Audit log.

Second Record

type=CWD

In the second record, the type field value is CWD — current working directory. This type is used to record the working directory from which the process that invoked the system call specified in the first record was executed.

The purpose of this record is to record the current process’s location in case a relative path winds up being captured in the associated PATH record. This way the absolute path can be reconstructed.

msg=audit(1364481363.243:24287)
The msg field holds the same time stamp and ID value as the value in the first record. The time stamp is using the Unix time format - seconds since 00:00:00 UTC on 1 January 1970.
cwd="/home/user_name"
The cwd field contains the path to the directory in which the system call was invoked.

Third Record

type=PATH
In the third record, the type field value is PATH. An Audit event contains a PATH-type record for every path that is passed to the system call as an argument. In this Audit event, only one path (/etc/ssh/sshd_config) was used as an argument.
msg=audit(1364481363.243:24287):
The msg field holds the same time stamp and ID value as the value in the first and second record.
item=0
The item field indicates which item, of the total number of items referenced in the SYSCALL type record, the current record is. This number is zero-based; a value of 0 means it is the first item.
name="/etc/ssh/sshd_config"
The name field records the path of the file or directory that was passed to the system call as an argument. In this case, it was the /etc/ssh/sshd_config file.
inode=409248

The inode field contains the inode number associated with the file or directory recorded in this event. The following command displays the file or directory that is associated with the 409248 inode number:

find / -inum 409248 -print
/etc/ssh/sshd_config
dev=fd:00
The dev field specifies the minor and major ID of the device that contains the file or directory recorded in this event. In this case, the value represents the /dev/fd/0 device.
mode=0100600
The mode field records the file or directory permissions, encoded in numerical notation as returned by the stat command in the st_mode field. See the stat(2) man page for more information. In this case, 0100600 can be interpreted as -rw-------, meaning that only the root user has read and write permissions to the /etc/ssh/sshd_config file.
ouid=0
The ouid field records the object owner’s user ID.
ogid=0
The ogid field records the object owner’s group ID.
rdev=00:00
The rdev field contains a recorded device identifier for special files only. In this case, it is not used as the recorded file is a regular file.
obj=system_u:object_r:etc_t:s0
The obj field records the SELinux context with which the recorded file or directory was labeled at the time of execution.
nametype=NORMAL
The nametype field records the intent of each path record’s operation in the context of a given syscall.
cap_fp=none
The cap_fp field records data related to the setting of a permitted file system-based capability of the file or directory object.
cap_fi=none
The cap_fi field records data related to the setting of an inherited file system-based capability of the file or directory object.
cap_fe=0
The cap_fe field records the setting of the effective bit of the file system-based capability of the file or directory object.
cap_fver=0
The cap_fver field records the version of the file system-based capability of the file or directory object.

Fourth Record

type=PROCTITLE
The type field contains the type of the record. In this example, the PROCTITLE value specifies that this record gives the full command-line that triggered this Audit event, triggered by a system call to the kernel.
proctitle=636174002F6574632F7373682F737368645F636F6E666967
The proctitle field records the full command-line of the command that was used to invoke the analyzed process. The field is encoded in hexadecimal notation to not allow the user to influence the Audit log parser. The text decodes to the command that triggered this Audit event. When searching Audit records with the ausearch command, use the -i or --interpret option to automatically convert hexadecimal values into their human-readable equivalents. The 636174002F6574632F7373682F737368645F636F6E666967 value is interpreted as cat /etc/ssh/sshd_config.

11.6. Using auditctl for defining and executing Audit rules

The Audit system operates on a set of rules that define what is captured in the log files. Audit rules can be set either on the command line using the auditctl utility or in the /etc/audit/rules.d/ directory.

The auditctl command enables you to control the basic functionality of the Audit system and to define rules that decide which Audit events are logged.

File-system rules examples

  1. To define a rule that logs all write access to, and every attribute change of, the /etc/passwd file:

    # auditctl -w /etc/passwd -p wa -k passwd_changes
  2. To define a rule that logs all write access to, and every attribute change of, all the files in the /etc/selinux/ directory:

    # auditctl -w /etc/selinux/ -p wa -k selinux_changes

System-call rules examples

  1. To define a rule that creates a log entry every time the adjtimex or settimeofday system calls are used by a program, and the system uses the 64-bit architecture:

    # auditctl -a always,exit -F arch=b64 -S adjtimex -S settimeofday -k time_change
  2. To define a rule that creates a log entry every time a file is deleted or renamed by a system user whose ID is 1000 or larger:

    # auditctl -a always,exit -S unlink -S unlinkat -S rename -S renameat -F auid>=1000 -F auid!=4294967295 -k delete

    Note that the -F auid!=4294967295 option is used to exclude users whose login UID is not set.

Executable-file rules

To define a rule that logs all execution of the /bin/id program, execute the following command:

# auditctl -a always,exit -F exe=/bin/id -F arch=b64 -S execve -k execution_bin_id

Additional resources

  • auditctl(8) man page.

11.7. Defining persistent Audit rules

To define Audit rules that are persistent across reboots, you must either directly include them in the /etc/audit/rules.d/audit.rules file or use the augenrules program that reads rules located in the /etc/audit/rules.d/ directory.

Note that the /etc/audit/audit.rules file is generated whenever the auditd service starts. Files in /etc/audit/rules.d/ use the same auditctl command-line syntax to specify the rules. Empty lines and text following a hash sign (#) are ignored.

Furthermore, you can use the auditctl command to read rules from a specified file using the -R option, for example:

# auditctl -R /usr/share/audit/sample-rules/30-stig.rules

11.8. Pre-configured Audit rules files for compliance with standards

To configure Audit for compliance with a specific certification standard, such as OSPP, PCI DSS, or STIG, you can use the set of pre-configured rules files installed with the audit package as a starting point. The sample rules are located in the /usr/share/audit/sample-rules directory.

Warning

The Audit sample rules in the sample-rules directory are not exhaustive nor up to date because security standards are dynamic and subject to change. These rules are provided only to demonstrate how Audit rules can be structured and written. They do not ensure immediate compliance with the latest security standards. To bring your system into compliance with the latest security standards according to specific security guidelines, use the SCAP-based security compliance tools.

30-nispom.rules
Audit rule configuration that meets the requirements specified in the Information System Security chapter of the National Industrial Security Program Operating Manual.
30-ospp-v42*.rules
Audit rule configuration that meets the requirements defined in the OSPP (Protection Profile for General Purpose Operating Systems) profile version 4.2.
30-pci-dss-v31.rules
Audit rule configuration that meets the requirements set by Payment Card Industry Data Security Standard (PCI DSS) v3.1.
30-stig.rules
Audit rule configuration that meets the requirements set by Security Technical Implementation Guides (STIG).

To use these configuration files, copy them to the /etc/audit/rules.d/ directory and use the augenrules --load command, for example:

# cd /usr/share/audit/sample-rules/
# cp 10-base-config.rules 30-stig.rules 31-privileged.rules 99-finalize.rules /etc/audit/rules.d/
# augenrules --load

You can order Audit rules using a numbering scheme. See the /usr/share/audit/sample-rules/README-rules file for more information.

Additional resources

  • audit.rules(7) man page.

11.9. Using augenrules to define persistent rules

The augenrules script reads rules located in the /etc/audit/rules.d/ directory and compiles them into an audit.rules file. This script processes all files that end with .rules in a specific order based on their natural sort order. The files in this directory are organized into groups with the following meanings:

10
Kernel and auditctl configuration
20
Rules that could match general rules but you want a different match
30
Main rules
40
Optional rules
50
Server-specific rules
70
System local rules
90
Finalize (immutable)

The rules are not meant to be used all at once. They are pieces of a policy that should be thought out and individual files copied to /etc/audit/rules.d/. For example, to set a system up in the STIG configuration, copy rules 10-base-config, 30-stig, 31-privileged, and 99-finalize.

Once you have the rules in the /etc/audit/rules.d/ directory, load them by running the augenrules script with the --load directive:

# augenrules --load
/sbin/augenrules: No change
No rules
enabled 1
failure 1
pid 742
rate_limit 0
...

Additional resources

  • audit.rules(8) and augenrules(8) man pages.

11.10. Disabling augenrules

Use the following steps to disable the augenrules utility. This switches Audit to use rules defined in the /etc/audit/audit.rules file.

Procedure

  1. Copy the /usr/lib/systemd/system/auditd.service file to the /etc/systemd/system/ directory:

    # cp -f /usr/lib/systemd/system/auditd.service /etc/systemd/system/
  2. Edit the /etc/systemd/system/auditd.service file in a text editor of your choice, for example:

    # vi /etc/systemd/system/auditd.service
  3. Comment out the line containing augenrules, and uncomment the line containing the auditctl -R command:

    #ExecStartPost=-/sbin/augenrules --load
    ExecStartPost=-/sbin/auditctl -R /etc/audit/audit.rules
  4. Reload the systemd daemon to fetch changes in the auditd.service file:

    # systemctl daemon-reload
  5. Restart the auditd service:

    # service auditd restart

Additional resources

11.11. Setting up Audit to monitor software updates

You can use the pre-configured rule 44-installers.rules to configure Audit to monitor the following utilities that install software:

  • dnf [2]
  • yum
  • pip
  • npm
  • cpan
  • gem
  • luarocks

To monitor the rpm utility, install the rpm-plugin-audit package. Audit will then generate SOFTWARE_UPDATE events when it installs or updates a package. You can list these events by entering ausearch -m SOFTWARE_UPDATE on the command line.

Note

Pre-configured rule files cannot be used on systems with the ppc64le and aarch64 architectures.

Prerequisites

Procedure

  1. Copy the pre-configured rule file 44-installers.rules from the /usr/share/audit/sample-rules/ directory to the /etc/audit/rules.d/ directory:

    # cp /usr/share/audit/sample-rules/44-installers.rules /etc/audit/rules.d/
  2. Load the audit rules:

    # augenrules --load

Verification

  1. List the loaded rules:

    # auditctl -l
    -p x-w /usr/bin/dnf-3 -k software-installer
    -p x-w /usr/bin/yum -k software-installer
    -p x-w /usr/bin/pip -k software-installer
    -p x-w /usr/bin/npm -k software-installer
    -p x-w /usr/bin/cpan -k software-installer
    -p x-w /usr/bin/gem -k software-installer
    -p x-w /usr/bin/luarocks -k software-installer
  2. Perform an installation, for example:

    # dnf reinstall -y vim-enhanced
  3. Search the Audit log for recent installation events, for example:

    # ausearch -ts recent -k software-installer
    ––––
    time->Thu Dec 16 10:33:46 2021
    type=PROCTITLE msg=audit(1639668826.074:298): proctitle=2F7573722F6C6962657865632F706C6174666F726D2D707974686F6E002F7573722F62696E2F646E66007265696E7374616C6C002D790076696D2D656E68616E636564
    type=PATH msg=audit(1639668826.074:298): item=2 name="/lib64/ld-linux-x86-64.so.2" inode=10092 dev=fd:01 mode=0100755 ouid=0 ogid=0 rdev=00:00 obj=system_u:object_r:ld_so_t:s0 nametype=NORMAL cap_fp=0 cap_fi=0 cap_fe=0 cap_fver=0 cap_frootid=0
    type=PATH msg=audit(1639668826.074:298): item=1 name="/usr/libexec/platform-python" inode=4618433 dev=fd:01 mode=0100755 ouid=0 ogid=0 rdev=00:00 obj=system_u:object_r:bin_t:s0 nametype=NORMAL cap_fp=0 cap_fi=0 cap_fe=0 cap_fver=0 cap_frootid=0
    type=PATH msg=audit(1639668826.074:298): item=0 name="/usr/bin/dnf" inode=6886099 dev=fd:01 mode=0100755 ouid=0 ogid=0 rdev=00:00 obj=system_u:object_r:rpm_exec_t:s0 nametype=NORMAL cap_fp=0 cap_fi=0 cap_fe=0 cap_fver=0 cap_frootid=0
    type=CWD msg=audit(1639668826.074:298): cwd="/root"
    type=EXECVE msg=audit(1639668826.074:298): argc=5 a0="/usr/libexec/platform-python" a1="/usr/bin/dnf" a2="reinstall" a3="-y" a4="vim-enhanced"
    type=SYSCALL msg=audit(1639668826.074:298): arch=c000003e syscall=59 success=yes exit=0 a0=55c437f22b20 a1=55c437f2c9d0 a2=55c437f2aeb0 a3=8 items=3 ppid=5256 pid=5375 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts0 ses=3 comm="dnf" exe="/usr/libexec/platform-python3.6" subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key="software-installer"


[2] Because dnf is a symlink in RHEL, the path in the dnf Audit rule must include the target of the symlink. To receive correct Audit events, modify the 44-installers.rules file by changing the path=/usr/bin/dnf path to /usr/bin/dnf-3.

11.12. Monitoring user login times with Audit

To monitor which users logged in at specific times, you do not need to configure Audit in any special way. You can use the ausearch or aureport tools, which provide different ways of presenting the same information.

Prerequisites

Procedure

To display user log in times, use any one of the following commands:

  • Search the audit log for the USER_LOGIN message type:

    # ausearch -m USER_LOGIN -ts '12/02/2020' '18:00:00' -sv no
    time->Mon Nov 22 07:33:22 2021
    type=USER_LOGIN msg=audit(1637584402.416:92): pid=1939 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:sshd_t:s0-s0:c0.c1023 msg='op=login acct="(unknown)" exe="/usr/sbin/sshd" hostname=? addr=10.37.128.108 terminal=ssh res=failed'
    • You can specify the date and time with the -ts option. If you do not use this option, ausearch provides results from today, and if you omit time, ausearch provides results from midnight.
    • You can use the -sv yes option to filter out successful login attempts and -sv no for unsuccessful login attempts.
  • Pipe the raw output of the ausearch command into the aulast utility, which displays the output in a format similar to the output of the last command. For example:

    # ausearch --raw | aulast --stdin
    root     ssh          10.37.128.108    Mon Nov 22 07:33 - 07:33  (00:00)
    root     ssh          10.37.128.108    Mon Nov 22 07:33 - 07:33  (00:00)
    root     ssh          10.22.16.106     Mon Nov 22 07:40 - 07:40  (00:00)
    reboot   system boot  4.18.0-348.6.el8 Mon Nov 22 07:33
  • Display the list of login events by using the aureport command with the --login -i options.

    # aureport --login -i
    
    Login Report
    ============================================
    # date time auid host term exe success event
    ============================================
    1. 11/16/2021 13:11:30 root 10.40.192.190 ssh /usr/sbin/sshd yes 6920
    2. 11/16/2021 13:11:31 root 10.40.192.190 ssh /usr/sbin/sshd yes 6925
    3. 11/16/2021 13:11:31 root 10.40.192.190 ssh /usr/sbin/sshd yes 6930
    4. 11/16/2021 13:11:31 root 10.40.192.190 ssh /usr/sbin/sshd yes 6935
    5. 11/16/2021 13:11:33 root 10.40.192.190 ssh /usr/sbin/sshd yes 6940
    6. 11/16/2021 13:11:33 root 10.40.192.190 /dev/pts/0 /usr/sbin/sshd yes 6945

Additional resources

  • The ausearch(8) man page.
  • The aulast(8) man page.
  • The aureport(8) man page.

Chapter 12. Blocking and allowing applications by using fapolicyd

Setting and enforcing a policy that either allows or denies application execution based on a rule set efficiently prevents the execution of unknown and potentially malicious software.

12.1. Introduction to fapolicyd

The fapolicyd software framework controls the execution of applications based on a user-defined policy. This is one of the most efficient ways to prevent running untrusted and possibly malicious applications on the system.

The fapolicyd framework provides the following components:

  • fapolicyd service
  • fapolicyd command-line utilities
  • fapolicyd RPM plugin
  • fapolicyd rule language
  • fagenrules script

The administrator can define the allow and deny execution rules for any application with the possibility of auditing based on a path, hash, MIME type, or trust.

The fapolicyd framework introduces the concept of trust. An application is trusted when it is properly installed by the system package manager, and therefore it is registered in the system RPM database. The fapolicyd daemon uses the RPM database as a list of trusted binaries and scripts. The fapolicyd RPM plugin registers any system update that is handled by either the DNF package manager or the RPM Package Manager. The plugin notifies the fapolicyd daemon about changes in this database. Other ways of adding applications require the creation of custom rules and restarting the fapolicyd service.

The fapolicyd service configuration is located in the /etc/fapolicyd/ directory with the following structure:

  • The /etc/fapolicyd/fapolicyd.trust file contains a list of trusted files. You can also use multiple trust files in the /etc/fapolicyd/trust.d/ directory.
  • The /etc/fapolicyd/rules.d/ directory for files containing allow and deny execution rules. The fagenrules script merges these component rules files to the /etc/fapolicyd/compiled.rules file.
  • The fapolicyd.conf file contains the daemon’s configuration options. This file is useful primarily for performance-tuning purposes.

Rules in /etc/fapolicyd/rules.d/ are organized in several files, each representing a different policy goal. The numbers at the beginning of the corresponding file names determine the order in /etc/fapolicyd/compiled.rules:

10
Language rules.
20
Dracut-related Rules.
21
rules for updaters.
30
Patterns.
40
ELF rules.
41
Shared objects rules.
42
Trusted ELF rules.
70
Trusted language rules.
72
Shell rules.
90
Deny execute rules.
95
Allow open rules.

You can use one of the following ways for fapolicyd integrity checking:

  • File-size checking
  • Comparing SHA-256 hashes
  • Integrity Measurement Architecture (IMA) subsystem

By default, fapolicyd does no integrity checking. Integrity checking based on the file size is fast, but an attacker can replace the content of the file and preserve its byte size. Computing and checking SHA-256 checksums is more secure, but it affects the performance of the system. The integrity = ima option in fapolicyd.conf requires support for files extended attributes (also known as xattr) on all file systems containing executable files.

Additional resources

12.2. Deploying fapolicyd

To deploy the fapolicyd framework in RHEL:

Procedure

  1. Install the fapolicyd package:

    # dnf install fapolicyd
  2. Enable and start the fapolicyd service:

    # systemctl enable --now fapolicyd

Verification

  1. Verify that the fapolicyd service is running correctly:

    # systemctl status fapolicyd
    ● fapolicyd.service - File Access Policy Daemon
       Loaded: loaded (/usr/lib/systemd/system/fapolicyd.service; enabled; vendor p>
       Active: active (running) since Tue 2019-10-15 18:02:35 CEST; 55s ago
      Process: 8818 ExecStart=/usr/sbin/fapolicyd (code=exited, status=0/SUCCESS)
     Main PID: 8819 (fapolicyd)
        Tasks: 4 (limit: 11500)
       Memory: 78.2M
       CGroup: /system.slice/fapolicyd.service
               └─8819 /usr/sbin/fapolicyd
    
    Oct 15 18:02:35 localhost.localdomain systemd[1]: Starting File Access Policy D>
    Oct 15 18:02:35 localhost.localdomain fapolicyd[8819]: Initialization of the da>
    Oct 15 18:02:35 localhost.localdomain fapolicyd[8819]: Reading RPMDB into memory
    Oct 15 18:02:35 localhost.localdomain systemd[1]: Started File Access Policy Da>
    Oct 15 18:02:36 localhost.localdomain fapolicyd[8819]: Creating database
  2. Log in as a user without root privileges, and check that fapolicyd is working, for example:

    $ cp /bin/ls /tmp
    $ /tmp/ls
    bash: /tmp/ls: Operation not permitted

12.3. Marking files as trusted using an additional source of trust

The fapolicyd framework trusts files contained in the RPM database. You can mark additional files as trusted by adding the corresponding entries to the /etc/fapolicyd/fapolicyd.trust plain-text file or the /etc/fapolicyd/trust.d/ directory, which supports separating a list of trusted files into more files. You can modify fapolicyd.trust or the files in /etc/fapolicyd/trust.d either directly using a text editor or through fapolicyd-cli commands.

Note

Marking files as trusted using fapolicyd.trust or trust.d/ is better than writing custom fapolicyd rules due to performance reasons.

Prerequisites

  • The fapolicyd framework is deployed on your system.

Procedure

  1. Copy your custom binary to the required directory, for example:

    $ cp /bin/ls /tmp
    $ /tmp/ls
    bash: /tmp/ls: Operation not permitted
  2. Mark your custom binary as trusted, and store the corresponding entry to the myapp file in /etc/fapolicyd/trust.d/:

    # fapolicyd-cli --file add /tmp/ls --trust-file myapp
    • If you skip the --trust-file option, then the previous command adds the corresponding line to /etc/fapolicyd/fapolicyd.trust.
    • To mark all existing files in a directory as trusted, provide the directory path as an argument of the --file option, for example: fapolicyd-cli --file add /tmp/my_bin_dir/ --trust-file myapp.
  3. Update the fapolicyd database:

    # fapolicyd-cli --update
Note

Changing the content of a trusted file or directory changes their checksum, and therefore fapolicyd no longer considers them trusted.

To make the new content trusted again, refresh the file trust database by using the fapolicyd-cli --file update command. If you do not provide any argument, the entire database refreshes. Alternatively, you can specify a path to a specific file or directory. Then, update the database by using fapolicyd-cli --update.

Verification

  1. Check that your custom binary can be now executed, for example:

    $ /tmp/ls
    ls

Additional resources

  • fapolicyd.trust(13) man page.

12.4. Adding custom allow and deny rules for fapolicyd

The default set of rules in the fapolicyd package does not affect system functions. For custom scenarios, such as storing binaries and scripts in a non-standard directory or adding applications without the dnf or rpm installers, you must either mark additional files as trusted or add new custom rules.

For basic scenarios, prefer Marking files as trusted using an additional source of trust. In more advanced scenarios such as allowing to execute a custom binary only for specific user and group identifiers, add new custom rules to the /etc/fapolicyd/rules.d/ directory.

The following steps demonstrate adding a new rule to allow a custom binary.

Prerequisites

  • The fapolicyd framework is deployed on your system.

Procedure

  1. Copy your custom binary to the required directory, for example:

    $ cp /bin/ls /tmp
    $ /tmp/ls
    bash: /tmp/ls: Operation not permitted
  2. Stop the fapolicyd service:

    # systemctl stop fapolicyd
  3. Use debug mode to identify a corresponding rule. Because the output of the fapolicyd --debug command is verbose and you can stop it only by pressing Ctrl+C or killing the corresponding process, redirect the error output to a file. In this case, you can limit the output only to access denials by using the --debug-deny option instead of --debug:

    # fapolicyd --debug-deny 2> fapolicy.output &
    [1] 51341

    Alternatively, you can run fapolicyd debug mode in another terminal.

  4. Repeat the command that fapolicyd denied:

    $ /tmp/ls
    bash: /tmp/ls: Operation not permitted
  5. Stop debug mode by resuming it in the foreground and pressing Ctrl+C:

    # fg
    fapolicyd --debug 2> fapolicy.output
    ^C
    ...

    Alternatively, kill the process of fapolicyd debug mode:

    # kill 51341
  6. Find a rule that denies the execution of your application:

    # cat fapolicy.output | grep 'deny_audit'
    ...
    rule=13 dec=deny_audit perm=execute auid=0 pid=6855 exe=/usr/bin/bash : path=/tmp/ls ftype=application/x-executable trust=0
  7. Locate the file that contains a rule that prevented the execution of your custom binary. In this case, the deny_audit perm=execute rule belongs to the 90-deny-execute.rules file:

    # ls /etc/fapolicyd/rules.d/
    10-languages.rules  40-bad-elf.rules	   72-shell.rules
    20-dracut.rules     41-shared-obj.rules    90-deny-execute.rules
    21-updaters.rules   42-trusted-elf.rules   95-allow-open.rules
    30-patterns.rules   70-trusted-lang.rules
    
    
    # cat /etc/fapolicyd/rules.d/90-deny-execute.rules
    # Deny execution for anything untrusted
    
    deny_audit perm=execute all : all
  8. Add a new allow rule to the file that lexically precedes the rule file that contains the rule that denied the execution of your custom binary in the /etc/fapolicyd/rules.d/ directory:

    # touch /etc/fapolicyd/rules.d/80-myapps.rules
    # vi /etc/fapolicyd/rules.d/80-myapps.rules

    Insert the following rule to the 80-myapps.rules file:

    allow perm=execute exe=/usr/bin/bash trust=1 : path=/tmp/ls ftype=application/x-executable trust=0

    Alternatively, you can allow executions of all binaries in the /tmp directory by adding the following rule to the rule file in /etc/fapolicyd/rules.d/:

    allow perm=execute exe=/usr/bin/bash trust=1 : dir=/tmp/ trust=0
    Important

    To make a rule effective recursively on all directories under the specified directory, add a trailing slash to the value of the dir= parameter in the rule (/tmp/ in the previous example).

  9. To prevent changes in the content of your custom binary, define the required rule using an SHA-256 checksum:

    $ sha256sum /tmp/ls
    780b75c90b2d41ea41679fcb358c892b1251b68d1927c80fbc0d9d148b25e836  ls

    Change the rule to the following definition:

    allow perm=execute exe=/usr/bin/bash trust=1 : sha256hash=780b75c90b2d41ea41679fcb358c892b1251b68d1927c80fbc0d9d148b25e836
  10. Check that the list of compiled differs from the rule set in /etc/fapolicyd/rules.d/, and update the list, which is stored in the /etc/fapolicyd/compiled.rules file:

    # fagenrules --check
    /usr/sbin/fagenrules: Rules have changed and should be updated
    # fagenrules --load
  11. Check that your custom rule is in the list of fapolicyd rules before the rule that prevented the execution:

    # fapolicyd-cli --list
    ...
    13. allow perm=execute exe=/usr/bin/bash trust=1 : path=/tmp/ls ftype=application/x-executable trust=0
    14. deny_audit perm=execute all : all
    ...
  12. Start the fapolicyd service:

    # systemctl start fapolicyd

Verification

  1. Check that your custom binary can be now executed, for example:

    $ /tmp/ls
    ls

Additional resources

  • fapolicyd.rules(5) and fapolicyd-cli(1) man pages on your system.
  • The documentation installed with the fapolicyd package in the /usr/share/fapolicyd/sample-rules/README-rules file.

12.5. Enabling fapolicyd integrity checks

By default, fapolicyd does not perform integrity checking. You can configure fapolicyd to perform integrity checks by comparing either file sizes or SHA-256 hashes. You can also set integrity checks by using the Integrity Measurement Architecture (IMA) subsystem.

Prerequisites

  • The fapolicyd framework is deployed on your system.

Procedure

  1. Open the /etc/fapolicyd/fapolicyd.conf file in a text editor of your choice, for example:

    # vi /etc/fapolicyd/fapolicyd.conf
  2. Change the value of the integrity option from none to sha256, save the file, and exit the editor:

    integrity = sha256
  3. Restart the fapolicyd service:

    # systemctl restart fapolicyd

Verification

  1. Back up the file used for the verification:

    # cp /bin/more /bin/more.bak
  2. Change the content of the /bin/more binary:

    # cat /bin/less > /bin/more
  3. Use the changed binary as a regular user:

    # su example.user
    $ /bin/more /etc/redhat-release
    bash: /bin/more: Operation not permitted
  4. Revert the changes:

    # mv -f /bin/more.bak /bin/more

12.7. Configuring protection against unknown code execution with the fapolicyd RHEL system role

You can use the fapolicyd system role to prevent execution of unknown code by running an Ansible playbook.

Prerequisites

Procedure

  1. Create a playbook file, for example ~/playbook.yml, with the following content:

    ---
    - name: Preventing execution of unknown code
      hosts: all
      vars:
        fapolicyd_setup_integrity: sha256
        fapolicyd_setup_trust: rpmdb,file
        fapolicyd_add_trusted_file:
          - </usr/bin/my-ls>
          - </opt/third-party/app1>
          - </opt/third-party/app2>
      roles:
        - rhel-system-roles.fapolicyd

    You can further customize the protection by using the following variables of the linux-system-roles.fapolicyd RHEL system role:

    fapolicyd_setup_integrity
    You can set one of the following types of integrity: none, sha256, and size.
    fapolicyd_setup_trust
    You can set trust file types file,rpmd, and deb.
    fapolicyd_add_trusted_file
    You can list executable files that you trust and that fapolicyd does not prevent from executing.
  2. Validate the playbook syntax:

    # ansible-playbook ~/playbook.yml --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    # ansible-playbook ~/playbook.yml

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.fapolicyd/README.md file

12.8. Additional resources

  • fapolicyd-related man pages listed by using the man -k fapolicyd command.
  • The FOSDEM 2020 fapolicyd presentation.

Chapter 13. Protecting systems against intrusive USB devices

USB devices can be loaded with spyware, malware, or trojans, which can steal your data or damage your system. As a Red Hat Enterprise Linux administrator, you can prevent such USB attacks with USBGuard.

13.1. USBGuard

With the USBGuard software framework, you can protect your systems against intrusive USB devices by using basic lists of permitted and forbidden devices based on the USB device authorization feature in the kernel.

The USBGuard framework provides the following components:

  • The system service component with an inter-process communication (IPC) interface for dynamic interaction and policy enforcement
  • The command-line interface to interact with a running usbguard system service
  • The rule language for writing USB device authorization policies
  • The C++ API for interacting with the system service component implemented in a shared library

The usbguard system service configuration file (/etc/usbguard/usbguard-daemon.conf) includes the options to authorize the users and groups to use the IPC interface.

Important

The system service provides the USBGuard public IPC interface. In Red Hat Enterprise Linux, the access to this interface is limited to the root user only by default.

Consider setting either the IPCAccessControlFiles option (recommended) or the IPCAllowedUsers and IPCAllowedGroups options to limit access to the IPC interface.

Ensure that you do not leave the Access Control List (ACL) unconfigured as this exposes the IPC interface to all local users and allows them to manipulate the authorization state of USB devices and modify the USBGuard policy.

13.2. Installing USBGuard

Use this procedure to install and initiate the USBGuard framework.

Procedure

  1. Install the usbguard package:

    # dnf install usbguard
  2. Create an initial rule set:

    # usbguard generate-policy > /etc/usbguard/rules.conf
  3. Start the usbguard daemon and ensure that it starts automatically on boot:

    # systemctl enable --now usbguard

Verification

  1. Verify that the usbguard service is running:

    # systemctl status usbguard
    ● usbguard.service - USBGuard daemon
       Loaded: loaded (/usr/lib/systemd/system/usbguard.service; enabled; vendor preset: disabled)
       Active: active (running) since Thu 2019-11-07 09:44:07 CET; 3min 16s ago
         Docs: man:usbguard-daemon(8)
     Main PID: 6122 (usbguard-daemon)
        Tasks: 3 (limit: 11493)
       Memory: 1.2M
       CGroup: /system.slice/usbguard.service
               └─6122 /usr/sbin/usbguard-daemon -f -s -c /etc/usbguard/usbguard-daemon.conf
    
    Nov 07 09:44:06 localhost.localdomain systemd[1]: Starting USBGuard daemon...
    Nov 07 09:44:07 localhost.localdomain systemd[1]: Started USBGuard daemon.
  2. List USB devices recognized by USBGuard:

    # usbguard list-devices
    4: allow id 1d6b:0002 serial "0000:02:00.0" name "xHCI Host Controller" hash...

Additional resources

  • usbguard(1) and usbguard-daemon.conf(5) man pages.

13.3. Blocking and authorizing a USB device by using CLI

You can set USBGuard to authorize and block a USB device by using the usbguard command in your terminal.

Prerequisites

  • The usbguard service is installed and running.

Procedure

  1. List USB devices recognized by USBGuard, for example:

    # usbguard list-devices
    1: allow id 1d6b:0002 serial "0000:00:06.7" name "EHCI Host Controller" hash "JDOb0BiktYs2ct3mSQKopnOOV2h9MGYADwhT+oUtF2s=" parent-hash "4PHGcaDKWtPjKDwYpIRG722cB9SlGz9l9Iea93+Gt9c=" via-port "usb1" with-interface 09:00:00
    ...
    6: block id 1b1c:1ab1 serial "000024937962" name "Voyager" hash "CrXgiaWIf2bZAU+5WkzOE7y0rdSO82XMzubn7HDb95Q=" parent-hash "JDOb0BiktYs2ct3mSQKopnOOV2h9MGYADwhT+oUtF2s=" via-port "1-3" with-interface 08:06:50
  2. Authorize the device <6> to interact with the system:

    # usbguard allow-device <6>
  3. Deauthorize and remove the device <6>:

    # usbguard reject-device <6>
  4. Deauthorize and retain the device <6>:

    # usbguard block-device <6>
Note

USBGuard uses the terms block and reject with the following meanings:

block
Do not interact with this device for now.
reject
Ignore this device as if it does not exist.

Additional resources

  • usbguard(1) man page
  • usbguard --help command

13.4. Permanently blocking and authorizing a USB device

You can permanently block and authorize a USB device by using the -p option. This adds a device-specific rule to the current policy.

Prerequisites

  • The usbguard service is installed and running.

Procedure

  1. Configure SELinux to allow the usbguard daemon to write rules.

    1. Display the semanage Booleans relevant to usbguard.

      # semanage boolean -l | grep usbguard
      usbguard_daemon_write_conf     (off  ,  off)  Allow usbguard to daemon write conf
      usbguard_daemon_write_rules    (on   ,   on)  Allow usbguard to daemon write rules
    2. Optional: If the usbguard_daemon_write_rules Boolean is turned off, turn it on.

      # semanage boolean -m --on usbguard_daemon_write_rules
  2. List USB devices recognized by USBGuard:

    # usbguard list-devices
    1: allow id 1d6b:0002 serial "0000:00:06.7" name "EHCI Host Controller" hash "JDOb0BiktYs2ct3mSQKopnOOV2h9MGYADwhT+oUtF2s=" parent-hash "4PHGcaDKWtPjKDwYpIRG722cB9SlGz9l9Iea93+Gt9c=" via-port "usb1" with-interface 09:00:00
    ...
    6: block id 1b1c:1ab1 serial "000024937962" name "Voyager" hash "CrXgiaWIf2bZAU+5WkzOE7y0rdSO82XMzubn7HDb95Q=" parent-hash "JDOb0BiktYs2ct3mSQKopnOOV2h9MGYADwhT+oUtF2s=" via-port "1-3" with-interface 08:06:50
  3. Permanently authorize device 6 to interact with the system:

    # usbguard allow-device 6 -p
  4. Permanently deauthorize and remove device 6:

    # usbguard reject-device 6 -p
  5. Permanently deauthorize and retain device 6:

    # usbguard block-device 6 -p
Note

USBGuard uses the terms block and reject with the following meanings:

block
Do not interact with this device for now.
reject
Ignore this device as if it does not exist.

Verification

  1. Check that USBGuard rules include the changes you made.

    # usbguard list-rules

Additional resources

  • usbguard(1) man page.
  • Built-in help listed by using the usbguard --help command.

13.5. Creating a custom policy for USB devices

The following procedure contains steps for creating a rule set for USB devices that reflects the requirements of your scenario.

Prerequisites

  • The usbguard service is installed and running.
  • The /etc/usbguard/rules.conf file contains an initial rule set generated by the usbguard generate-policy command.

Procedure

  1. Create a policy which authorizes the currently connected USB devices, and store the generated rules to the rules.conf file:

    # usbguard generate-policy --no-hashes > ./rules.conf

    The --no-hashes option does not generate hash attributes for devices. Avoid hash attributes in your configuration settings because they might not be persistent.

  2. Edit the rules.conf file with a text editor of your choice, for example:

    # vi ./rules.conf
  3. Add, remove, or edit the rules as required. For example, the following rule allows only devices with a single mass storage interface to interact with the system:

    allow with-interface equals { 08:*:* }

    See the usbguard-rules.conf(5) man page for a detailed rule-language description and more examples.

  4. Install the updated policy:

    # install -m 0600 -o root -g root rules.conf /etc/usbguard/rules.conf
  5. Restart the usbguard daemon to apply your changes:

    # systemctl restart usbguard

Verification

  1. Check that your custom rules are in the active policy, for example:

    # usbguard list-rules
    ...
    4: allow with-interface 08:*:*
    ...

Additional resources

  • usbguard-rules.conf(5) man page.

13.6. Creating a structured custom policy for USB devices

You can organize your custom USBGuard policy in several .conf files within the /etc/usbguard/rules.d/ directory. The usbguard-daemon then combines the main rules.conf file with the .conf files within the directory in alphabetical order.

Prerequisites

  • The usbguard service is installed and running.

Procedure

  1. Create a policy which authorizes the currently connected USB devices, and store the generated rules to a new .conf file, for example, policy.conf.

    # usbguard generate-policy --no-hashes > ./policy.conf

    The --no-hashes option does not generate hash attributes for devices. Avoid hash attributes in your configuration settings because they might not be persistent.

  2. Display the policy.conf file with a text editor of your choice, for example:

    # vi ./policy.conf
    ...
    allow id 04f2:0833 serial "" name "USB Keyboard" via-port "7-2" with-interface { 03:01:01 03:00:00 } with-connect-type "unknown"
    ...
  3. Move selected lines into a separate .conf file.

    Note

    The two digits at the beginning of the file name specify the order in which the daemon reads the configuration files.

    For example, copy the rules for your keyboards into a new .conf file.

    # grep "USB Keyboard" ./policy.conf > ./10keyboards.conf
  4. Install the new policy to the /etc/usbguard/rules.d/ directory.

    # install -m 0600 -o root -g root 10keyboards.conf /etc/usbguard/rules.d/10keyboards.conf
  5. Move the rest of the lines to a main rules.conf file.

    # grep -v "USB Keyboard" ./policy.conf > ./rules.conf
  6. Install the remaining rules.

    # install -m 0600 -o root -g root rules.conf /etc/usbguard/rules.conf
  7. Restart the usbguard daemon to apply your changes.

    # systemctl restart usbguard

Verification

  1. Display all active USBGuard rules.

    # usbguard list-rules
    ...
    15: allow id 04f2:0833 serial "" name "USB Keyboard" hash "kxM/iddRe/WSCocgiuQlVs6Dn0VEza7KiHoDeTz0fyg=" parent-hash "2i6ZBJfTl5BakXF7Gba84/Cp1gslnNc1DM6vWQpie3s=" via-port "7-2" with-interface { 03:01:01 03:00:00 } with-connect-type "unknown"
    ...
  2. Display the contents of the rules.conf file and all the .conf files in the /etc/usbguard/rules.d/ directory.

    # cat /etc/usbguard/rules.conf /etc/usbguard/rules.d/*.conf
  3. Verify that the active rules contain all the rules from the files and are in the correct order.

Additional resources

  • usbguard-rules.conf(5) man page.

13.7. Authorizing users and groups to use the USBGuard IPC interface

Use this procedure to authorize a specific user or a group to use the USBGuard public IPC interface. By default, only the root user can use this interface.

Prerequisites

  • The usbguard service is installed and running.
  • The /etc/usbguard/rules.conf file contains an initial rule set generated by the usbguard generate-policy command.

Procedure

  1. Edit the /etc/usbguard/usbguard-daemon.conf file with a text editor of your choice:

    # vi /etc/usbguard/usbguard-daemon.conf
  2. For example, add a line with a rule that allows all users in the wheel group to use the IPC interface, and save the file:

    IPCAllowGroups=wheel
  3. You can add users or groups also with the usbguard command. For example, the following command enables the joesec user to have full access to the Devices and Exceptions sections. Furthermore, joesec can list and modify the current policy:

    # usbguard add-user joesec --devices ALL --policy modify,list --exceptions ALL

    To remove the granted permissions for the joesec user, use the usbguard remove-user joesec command.

  4. Restart the usbguard daemon to apply your changes:

    # systemctl restart usbguard

Additional resources

  • usbguard(1) and usbguard-rules.conf(5) man pages.

13.8. Logging USBguard authorization events to the Linux Audit log

Use the following steps to integrate logging of USBguard authorization events to the standard Linux Audit log. By default, the usbguard daemon logs events to the /var/log/usbguard/usbguard-audit.log file.

Prerequisites

  • The usbguard service is installed and running.
  • The auditd service is running.

Procedure

  1. Edit the usbguard-daemon.conf file with a text editor of your choice:

    # vi /etc/usbguard/usbguard-daemon.conf
  2. Change the AuditBackend option from FileAudit to LinuxAudit:

    AuditBackend=LinuxAudit
  3. Restart the usbguard daemon to apply the configuration change:

    # systemctl restart usbguard

Verification

  1. Query the audit daemon log for a USB authorization event, for example:

    # ausearch -ts recent -m USER_DEVICE

Additional resources

  • usbguard-daemon.conf(5) man page.

13.9. Additional resources

  • usbguard(1), usbguard-rules.conf(5), usbguard-daemon(8), and usbguard-daemon.conf(5) man pages.
  • USBGuard Homepage.

Chapter 14. Configuring a remote logging solution

To ensure that logs from various machines in your environment are recorded centrally on a logging server, you can configure the Rsyslog application to record logs that fit specific criteria from the client system to the server.

14.1. The Rsyslog logging service

The Rsyslog application, in combination with the systemd-journald service, provides local and remote logging support in Red Hat Enterprise Linux. The rsyslogd daemon continuously reads syslog messages received by the systemd-journald service from the Journal. rsyslogd then filters and processes these syslog events and records them to rsyslog log files or forwards them to other services according to its configuration.

The rsyslogd daemon also provides extended filtering, encryption protected relaying of messages, input and output modules, and support for transportation using the TCP and UDP protocols.

In /etc/rsyslog.conf, which is the main configuration file for rsyslog, you can specify the rules according to which rsyslogd handles the messages. Generally, you can classify messages by their source and topic (facility) and urgency (priority), and then assign an action that should be performed when a message fits these criteria.

In /etc/rsyslog.conf, you can also see a list of log files maintained by rsyslogd. Most log files are located in the /var/log/ directory. Some applications, such as httpd and samba, store their log files in a subdirectory within /var/log/.

Additional resources

  • The rsyslogd(8) and rsyslog.conf(5) man pages.
  • Documentation installed with the rsyslog-doc package in the /usr/share/doc/rsyslog/html/index.html file.

14.2. Installing Rsyslog documentation

The Rsyslog application has extensive online documentation that is available at https://www.rsyslog.com/doc/, but you can also install the rsyslog-doc documentation package locally.

Prerequisites

  • You have activated the AppStream repository on your system.
  • You are authorized to install new packages using sudo.

Procedure

  • Install the rsyslog-doc package:

    # dnf install rsyslog-doc

Verification

  • Open the /usr/share/doc/rsyslog/html/index.html file in a browser of your choice, for example:

    $ firefox /usr/share/doc/rsyslog/html/index.html &

14.3. Configuring a server for remote logging over TCP

The Rsyslog application enables you to both run a logging server and configure individual systems to send their log files to the logging server. To use remote logging through TCP, configure both the server and the client. The server collects and analyzes the logs sent by one or more client systems.

With the Rsyslog application, you can maintain a centralized logging system where log messages are forwarded to a server over the network. To avoid message loss when the server is not available, you can configure an action queue for the forwarding action. This way, messages that failed to be sent are stored locally until the server is reachable again. Note that such queues cannot be configured for connections using the UDP protocol.

The omfwd plug-in provides forwarding over UDP or TCP. The default protocol is UDP. Because the plug-in is built in, it does not have to be loaded.

By default, rsyslog uses TCP on port 514.

Prerequisites

  • Rsyslog is installed on the server system.
  • You are logged in as root on the server.
  • The policycoreutils-python-utils package is installed for the optional step using the semanage command.
  • The firewalld service is running.

Procedure

  1. Optional: To use a different port for rsyslog traffic, add the syslogd_port_t SELinux type to port. For example, enable port 30514:

    # semanage port -a -t syslogd_port_t -p tcp 30514
  2. Optional: To use a different port for rsyslog traffic, configure firewalld to allow incoming rsyslog traffic on that port. For example, allow TCP traffic on port 30514:

    # firewall-cmd --zone=<zone-name> --permanent --add-port=30514/tcp
    success
    # firewall-cmd --reload
  3. Create a new file in the /etc/rsyslog.d/ directory named, for example, remotelog.conf, and insert the following content:

    # Define templates before the rules that use them
    # Per-Host templates for remote systems
    template(name="TmplAuthpriv" type="list") {
        constant(value="/var/log/remote/auth/")
        property(name="hostname")
        constant(value="/")
        property(name="programname" SecurePath="replace")
        constant(value=".log")
        }
    
    template(name="TmplMsg" type="list") {
        constant(value="/var/log/remote/msg/")
        property(name="hostname")
        constant(value="/")
        property(name="programname" SecurePath="replace")
        constant(value=".log")
        }
    
    # Provides TCP syslog reception
    module(load="imtcp")
    
    # Adding this ruleset to process remote messages
    ruleset(name="remote1"){
         authpriv.*   action(type="omfile" DynaFile="TmplAuthpriv")
          *.info;mail.none;authpriv.none;cron.none
    action(type="omfile" DynaFile="TmplMsg")
    }
    
    input(type="imtcp" port="30514" ruleset="remote1")
  4. Save the changes to the /etc/rsyslog.d/remotelog.conf file.
  5. Test the syntax of the /etc/rsyslog.conf file:

    # rsyslogd -N 1
    rsyslogd: version 8.1911.0-2.el8, config validation run...
    rsyslogd: End of config validation run. Bye.
  6. Make sure the rsyslog service is running and enabled on the logging server:

    # systemctl status rsyslog
  7. Restart the rsyslog service.

    # systemctl restart rsyslog
  8. Optional: If rsyslog is not enabled, ensure the rsyslog service starts automatically after reboot:

    # systemctl enable rsyslog

Your log server is now configured to receive and store log files from the other systems in your environment.

Additional resources

  • rsyslogd(8), rsyslog.conf(5), semanage(8), and firewall-cmd(1) man pages.
  • Documentation installed with the rsyslog-doc package in the /usr/share/doc/rsyslog/html/index.html file.

14.4. Configuring remote logging to a server over TCP

You can configure a system for forwarding log messages to a server over the TCP protocol. The omfwd plug-in provides forwarding over UDP or TCP. The default protocol is UDP. Because the plug-in is built in, you do not have to load it.

Prerequisites

  • The rsyslog package is installed on the client systems that should report to the server.
  • You have configured the server for remote logging.
  • The specified port is permitted in SELinux and open in firewall.
  • The system contains the policycoreutils-python-utils package, which provides the semanage command for adding a non-standard port to the SELinux configuration.

Procedure

  1. Create a new file in the /etc/rsyslog.d/ directory named, for example, 10-remotelog.conf, and insert the following content:

    *.* action(type="omfwd"
          queue.type="linkedlist"
          queue.filename="example_fwd"
          action.resumeRetryCount="-1"
          queue.saveOnShutdown="on"
          target="example.com" port="30514" protocol="tcp"
         )

    Where:

    • The queue.type="linkedlist" setting enables a LinkedList in-memory queue,
    • The queue.filename setting defines a disk storage. The backup files are created with the example_fwd prefix in the working directory specified by the preceding global workDirectory directive.
    • The action.resumeRetryCount -1 setting prevents rsyslog from dropping messages when retrying to connect if server is not responding,
    • The queue.saveOnShutdown="on" setting saves in-memory data if rsyslog shuts down.
    • The last line forwards all received messages to the logging server. Port specification is optional.

      With this configuration, rsyslog sends messages to the server but keeps messages in memory if the remote server is not reachable. A file on disk is created only if rsyslog runs out of the configured memory queue space or needs to shut down, which benefits the system performance.

    Note

    Rsyslog processes configuration files /etc/rsyslog.d/ in the lexical order.

  2. Restart the rsyslog service.

    # systemctl restart rsyslog

Verification

To verify that the client system sends messages to the server, follow these steps:

  1. On the client system, send a test message:

    # logger test
  2. On the server system, view the /var/log/messages log, for example:

    # cat /var/log/remote/msg/hostname/root.log
    Feb 25 03:53:17 hostname root[6064]: test

    Where hostname is the host name of the client system. Note that the log contains the user name of the user that entered the logger command, in this case root.

Additional resources

  • rsyslogd(8) and rsyslog.conf(5) man pages.
  • Documentation installed with the rsyslog-doc package in the /usr/share/doc/rsyslog/html/index.html file.

14.5. Configuring TLS-encrypted remote logging

By default, Rsyslog sends remote-logging communication in the plain text format. If your scenario requires to secure this communication channel, you can encrypt it using TLS.

To use encrypted transport through TLS, configure both the server and the client. The server collects and analyzes the logs sent by one or more client systems.

You can use either the ossl network stream driver (OpenSSL) or the gtls stream driver (GnuTLS).

Note

If you have a separate system with higher security, for example, a system that is not connected to any network or has stricter authorizations, use the separate system as the certifying authority (CA).

You can customize your connection settings with stream drivers on the server side on the global, module, and input levels, and on the client side on the global and action levels. The more specific configuration overrides the more general configuration. This means, for example, that you can use ossl in global settings for most connections and gtls on the input and action settings only for specific connections.

Prerequisites

  • You have root access to both the client and server systems.
  • The following packages are installed on the server and the client systems:

    • The rsyslog package.
    • For the ossl network stream driver, the rsyslog-openssl package.
    • For the gtls network stream driver, the rsyslog-gnutls package.
    • For generating certificates by using the certtool command, the gnutls-utils package.
  • On your logging server, the following certificates are in the /etc/pki/ca-trust/source/anchors/ directory and your system configuration is updated by using the update-ca-trust command:

    • ca-cert.pem - a CA certificate that can verify keys and certificates on logging servers and clients.
    • server-cert.pem - a public key of the logging server.
    • server-key.pem - a private key of the logging server.
  • On your logging clients, the following certificates are in the /etc/pki/ca-trust/source/anchors/ directory and your system configuration is updated by using update-ca-trust:

    • ca-cert.pem - a CA certificate that can verify keys and certificates on logging servers and clients.
    • client-cert.pem - a public key of a client.
    • client-key.pem - a private key of a client.
    • If the server runs RHEL 9.2 or later and FIPS mode is enabled, clients must either support the Extended Master Secret (EMS) extension or use TLS 1.3. TLS 1.2 connections without EMS fail. For more information, see the TLS extension "Extended Master Secret" enforced Knowledgebase article.

Procedure

  1. Configure the server for receiving encrypted logs from your client systems:

    1. Create a new file in the /etc/rsyslog.d/ directory named, for example, securelogser.conf.
    2. To encrypt the communication, the configuration file must contain paths to certificate files on your server, a selected authentication method, and a stream driver that supports TLS encryption. Add the following lines to the /etc/rsyslog.d/securelogser.conf file:

      # Set certificate files
      global(
        DefaultNetstreamDriverCAFile="/etc/pki/ca-trust/source/anchors/ca-cert.pem"
        DefaultNetstreamDriverCertFile="/etc/pki/ca-trust/source/anchors/server-cert.pem"
        DefaultNetstreamDriverKeyFile="/etc/pki/ca-trust/source/anchors/server-key.pem"
      )
      
      # TCP listener
      module(
        load="imtcp"
        PermittedPeer=["client1.example.com", "client2.example.com"]
        StreamDriver.AuthMode="x509/name"
        StreamDriver.Mode="1"
        StreamDriver.Name="ossl"
      )
      
      # Start up listener at port 514
      input(
        type="imtcp"
        port="514"
      )
      Note

      If you prefer the GnuTLS driver, use the StreamDriver.Name="gtls" configuration option. See the documentation installed with the rsyslog-doc package for more information about less strict authentication modes than x509/name.

    3. Optional: From Rsyslog version 8.2310, which is provided in RHEL 9.4, you can customize the connection configuration. To do so, replace the input section with the following:

      input(
        type="imtcp"
        Port="50515"
        StreamDriver.Name="<driver>"
        streamdriver.CAFile="/etc/rsyslog.d/<ca1>.pem"
        streamdriver.CertFile="/etc/rsyslog.d/<server1-cert>.pem"
        streamdriver.KeyFile="/etc/rsyslog.d/<server1-key>.pem"
      )
      • Replace <driver> with ossl or gtls depending on the driver you want to use.
      • Replace <ca1> with the CA certificate, <server1-cert> with the certificate, and <server1-key> with the key of the customized connection.
    4. Save the changes to the /etc/rsyslog.d/securelogser.conf file.
    5. Verify the syntax of the /etc/rsyslog.conf file and any files in the /etc/rsyslog.d/ directory:

      # rsyslogd -N 1
      rsyslogd: version 8.1911.0-2.el8, config validation run (level 1)...
      rsyslogd: End of config validation run. Bye.
    6. Make sure the rsyslog service is running and enabled on the logging server:

      # systemctl status rsyslog
    7. Restart the rsyslog service:

      # systemctl restart rsyslog
    8. Optional: If Rsyslog is not enabled, ensure the rsyslog service starts automatically after reboot:

      # systemctl enable rsyslog
  2. Configure clients for sending encrypted logs to the server:

    1. On a client system, create a new file in the /etc/rsyslog.d/ directory named, for example, securelogcli.conf.
    2. Add the following lines to the /etc/rsyslog.d/securelogcli.conf file:

      # Set certificate files
      global(
        DefaultNetstreamDriverCAFile="/etc/pki/ca-trust/source/anchors/ca-cert.pem"
        DefaultNetstreamDriverCertFile="/etc/pki/ca-trust/source/anchors/client-cert.pem"
        DefaultNetstreamDriverKeyFile="/etc/pki/ca-trust/source/anchors/client-key.pem"
      )
      
      
      # Set up the action for all messages
      *.* action(
        type="omfwd"
        StreamDriver="ossl"
        StreamDriverMode="1"
        StreamDriverPermittedPeers="server.example.com"
        StreamDriverAuthMode="x509/name"
        target="server.example.com" port="514" protocol="tcp"
      )
      Note

      If you prefer the GnuTLS driver, use the StreamDriver.Name="gtls" configuration option.

    3. Optional: From Rsyslog version 8.2310, which is provided in RHEL 9.4, you can customize the connection configuration. To do so, replace the action section with the following:

      local1.* action(
        type="omfwd"
        StreamDriver="<driver>"
        StreamDriverMode="1"
        StreamDriverAuthMode="x509/certvalid"
        streamDriver.CAFile="/etc/rsyslog.d/<ca1>.pem"
        streamDriver.CertFile="/etc/rsyslog.d/<client1-cert>.pem"
        streamDriver.KeyFile="/etc/rsyslog.d/<client1-key>.pem"
        target="server.example.com" port="514" protocol="tcp"
        )
      • Replace <driver> with ossl or gtls depending on the driver you want to use.
      • Replace <ca1> with the CA certificate, <client1-cert> with the certificate, and <client1-key> with the key of the customized connection.
    4. Save the changes to the /etc/rsyslog.d/securelogcli.conf file.
    5. Verify the syntax of the /etc/rsyslog.conf file and other files in the /etc/rsyslog.d/ directory:

      # rsyslogd -N 1
      rsyslogd: version 8.1911.0-2.el8, config validation run (level 1)...
      rsyslogd: End of config validation run. Bye.
    6. Make sure the rsyslog service is running and enabled on the logging server:

      # systemctl status rsyslog
    7. Restart the rsyslog service:

      # systemctl restart rsyslog
    8. Optional: If Rsyslog is not enabled, ensure the rsyslog service starts automatically after reboot:

      # systemctl enable rsyslog

Verification

To verify that the client system sends messages to the server, follow these steps:

  1. On the client system, send a test message:

    # logger test
  2. On the server system, view the /var/log/messages log, for example:

    # cat /var/log/remote/msg/<hostname>/root.log
    Feb 25 03:53:17 <hostname> root[6064]: test

    Where <hostname> is the hostname of the client system. Note that the log contains the user name of the user that entered the logger command, in this case root.

Additional resources

  • certtool(1), openssl(1), update-ca-trust(8), rsyslogd(8), and rsyslog.conf(5) man pages.
  • Documentation installed with the rsyslog-doc package at /usr/share/doc/rsyslog/html/index.html.
  • Using the logging system role with TLS.

14.6. Configuring a server for receiving remote logging information over UDP

The Rsyslog application enables you to configure a system to receive logging information from remote systems. To use remote logging through UDP, configure both the server and the client. The receiving server collects and analyzes the logs sent by one or more client systems. By default, rsyslog uses UDP on port 514 to receive log information from remote systems.

Follow this procedure to configure a server for collecting and analyzing logs sent by one or more client systems over the UDP protocol.

Prerequisites

  • Rsyslog is installed on the server system.
  • You are logged in as root on the server.
  • The policycoreutils-python-utils package is installed for the optional step using the semanage command.
  • The firewalld service is running.

Procedure

  1. Optional: To use a different port for rsyslog traffic than the default port 514:

    1. Add the syslogd_port_t SELinux type to the SELinux policy configuration, replacing portno with the port number you want rsyslog to use:

      # semanage port -a -t syslogd_port_t -p udp portno
    2. Configure firewalld to allow incoming rsyslog traffic, replacing portno with the port number and zone with the zone you want rsyslog to use:

      # firewall-cmd --zone=zone --permanent --add-port=portno/udp
      success
      # firewall-cmd --reload
    3. Reload the firewall rules:

      # firewall-cmd --reload
  2. Create a new .conf file in the /etc/rsyslog.d/ directory, for example, remotelogserv.conf, and insert the following content:

    # Define templates before the rules that use them
    # Per-Host templates for remote systems
    template(name="TmplAuthpriv" type="list") {
        constant(value="/var/log/remote/auth/")
        property(name="hostname")
        constant(value="/")
        property(name="programname" SecurePath="replace")
        constant(value=".log")
        }
    
    template(name="TmplMsg" type="list") {
        constant(value="/var/log/remote/msg/")
        property(name="hostname")
        constant(value="/")
        property(name="programname" SecurePath="replace")
        constant(value=".log")
        }
    
    # Provides UDP syslog reception
    module(load="imudp")
    
    # This ruleset processes remote messages
    ruleset(name="remote1"){
         authpriv.*   action(type="omfile" DynaFile="TmplAuthpriv")
          *.info;mail.none;authpriv.none;cron.none
    action(type="omfile" DynaFile="TmplMsg")
    }
    
    input(type="imudp" port="514" ruleset="remote1")

    Where 514 is the port number rsyslog uses by default. You can specify a different port instead.

  3. Verify the syntax of the /etc/rsyslog.conf file and all .conf files in the /etc/rsyslog.d/ directory:

    # rsyslogd -N 1
    rsyslogd: version 8.1911.0-2.el8, config validation run...
  4. Restart the rsyslog service.

    # systemctl restart rsyslog
  5. Optional: If rsyslog is not enabled, ensure the rsyslog service starts automatically after reboot:

    # systemctl enable rsyslog

Additional resources

  • rsyslogd(8) , rsyslog.conf(5), semanage(8), and firewall-cmd(1) man pages.
  • Documentation installed with the rsyslog-doc package in the /usr/share/doc/rsyslog/html/index.html file.

14.7. Configuring remote logging to a server over UDP

You can configure a system for forwarding log messages to a server over the UDP protocol. The omfwd plug-in provides forwarding over UDP or TCP. The default protocol is UDP. Because the plug-in is built in, you do not have to load it.

Prerequisites

Procedure

  1. Create a new .conf file in the /etc/rsyslog.d/ directory, for example, 10-remotelogcli.conf, and insert the following content:

    *.* action(type="omfwd"
          queue.type="linkedlist"
          queue.filename="example_fwd"
          action.resumeRetryCount="-1"
          queue.saveOnShutdown="on"
          target="example.com" port="portno" protocol="udp"
         )

    Where:

    • The queue.type="linkedlist" setting enables a LinkedList in-memory queue.
    • The queue.filename setting defines a disk storage. The backup files are created with the example_fwd prefix in the working directory specified by the preceding global workDirectory directive.
    • The action.resumeRetryCount -1 setting prevents rsyslog from dropping messages when retrying to connect if the server is not responding.
    • The enabled queue.saveOnShutdown="on" setting saves in-memory data if rsyslog shuts down.
    • The portno value is the port number you want rsyslog to use. The default value is 514.
    • The last line forwards all received messages to the logging server, port specification is optional.

      With this configuration, rsyslog sends messages to the server but keeps messages in memory if the remote server is not reachable. A file on disk is created only if rsyslog runs out of the configured memory queue space or needs to shut down, which benefits the system performance.

    Note

    Rsyslog processes configuration files /etc/rsyslog.d/ in the lexical order.

  2. Restart the rsyslog service.

    # systemctl restart rsyslog
  3. Optional: If rsyslog is not enabled, ensure the rsyslog service starts automatically after reboot:

    # systemctl enable rsyslog

Verification

To verify that the client system sends messages to the server, follow these steps:

  1. On the client system, send a test message:

    # logger test
  2. On the server system, view the /var/log/remote/msg/hostname/root.log log, for example:

    # cat /var/log/remote/msg/hostname/root.log
    Feb 25 03:53:17 hostname root[6064]: test

    Where hostname is the host name of the client system. Note that the log contains the user name of the user that entered the logger command, in this case root.

Additional resources

  • rsyslogd(8) and rsyslog.conf(5) man pages.
  • Documentation installed with the rsyslog-doc package at /usr/share/doc/rsyslog/html/index.html.

14.8. Load balancing helper in Rsyslog

The RebindInterval setting specifies an interval at which the current connection is broken and is re-established. This setting applies to TCP, UDP, and RELP traffic. The load balancers perceive it as a new connection and forward the messages to another physical target system.

The RebindInterval setting proves to be helpful in scenarios when a target system has changed its IP address. The Rsyslog application caches the IP address when the connection establishes, therefore, the messages are sent to the same server. If the IP address changes, the UDP packets will be lost until the Rsyslog service restarts. Re-establishing the connection will ensure the IP to be resolved by DNS again.

action(type=”omfwd” protocol=”tcp” RebindInterval=”250” target=”example.com” port=”514” …)

action(type=”omfwd” protocol=”udp” RebindInterval=”250” target=”example.com” port=”514” …)

action(type=”omrelp” RebindInterval=”250” target=”example.com” port=”6514” …)

14.9. Configuring reliable remote logging

With the Reliable Event Logging Protocol (RELP), you can send and receive syslog messages over TCP with a much reduced risk of message loss. RELP provides reliable delivery of event messages, which makes it useful in environments where message loss is not acceptable. To use RELP, configure the imrelp input module, which runs on the server and receives the logs, and the omrelp output module, which runs on the client and sends logs to the logging server.

Prerequisites

  • You have installed the rsyslog, librelp, and rsyslog-relp packages on the server and the client systems.
  • The specified port is permitted in SELinux and open in the firewall.

Procedure

  1. Configure the client system for reliable remote logging:

    1. On the client system, create a new .conf file in the /etc/rsyslog.d/ directory named, for example, relpclient.conf, and insert the following content:

      module(load="omrelp")
      *.* action(type="omrelp" target="_target_IP_" port="_target_port_")

      Where:

      • target_IP is the IP address of the logging server.
      • target_port is the port of the logging server.
    2. Save the changes to the /etc/rsyslog.d/relpclient.conf file.
    3. Restart the rsyslog service.

      # systemctl restart rsyslog
    4. Optional: If rsyslog is not enabled, ensure the rsyslog service starts automatically after reboot:

      # systemctl enable rsyslog
  2. Configure the server system for reliable remote logging:

    1. On the server system, create a new .conf file in the /etc/rsyslog.d/ directory named, for example, relpserv.conf, and insert the following content:

      ruleset(name="relp"){
      *.* action(type="omfile" file="_log_path_")
      }
      
      
      module(load="imrelp")
      input(type="imrelp" port="_target_port_" ruleset="relp")

      Where:

      • log_path specifies the path for storing messages.
      • target_port is the port of the logging server. Use the same value as in the client configuration file.
    2. Save the changes to the /etc/rsyslog.d/relpserv.conf file.
    3. Restart the rsyslog service.

      # systemctl restart rsyslog
    4. Optional: If rsyslog is not enabled, ensure the rsyslog service starts automatically after reboot:

      # systemctl enable rsyslog

Verification

To verify that the client system sends messages to the server, follow these steps:

  1. On the client system, send a test message:

    # logger test
  2. On the server system, view the log at the specified log_path, for example:

    # cat /var/log/remote/msg/hostname/root.log
    Feb 25 03:53:17 hostname root[6064]: test

    Where hostname is the host name of the client system. Note that the log contains the user name of the user that entered the logger command, in this case root.

Additional resources

  • rsyslogd(8) and rsyslog.conf(5) man pages.
  • Documentation installed with the rsyslog-doc package in the /usr/share/doc/rsyslog/html/index.html file.

14.10. Supported Rsyslog modules

To expand the functionality of the Rsyslog application, you can use specific modules. Modules provide additional inputs (Input Modules), outputs (Output Modules), and other functionalities. A module can also provide additional configuration directives that become available after you load the module.

You can list the input and output modules installed on your system by entering the following command:

# ls /usr/lib64/rsyslog/{i,o}m*

You can view the list of all available rsyslog modules in the /usr/share/doc/rsyslog/html/configuration/modules/idx_output.html file after you install the rsyslog-doc package.

14.11. Configuring the netconsole service to log kernel messages to a remote host

When logging to disk or using a serial console is not possible, you can use the netconsole kernel module and the same-named service to log kernel messages over a network to a remote rsyslog service.

Prerequisites

  • A system log service, such as rsyslog is installed on the remote host.
  • The remote system log service is configured to receive incoming log entries from this host.

Procedure

  1. Install the netconsole-service package:

    # dnf install netconsole-service
  2. Edit the /etc/sysconfig/netconsole file and set the SYSLOGADDR parameter to the IP address of the remote host:

    # SYSLOGADDR=192.0.2.1
  3. Enable and start the netconsole service:

    # systemctl enable --now netconsole

Verification steps

  • Display the /var/log/messages file on the remote system log server.

14.12. Additional resources

Chapter 15. Using the logging system role

As a system administrator, you can use the logging system role to configure a Red Hat Enterprise Linux host as a logging server to collect logs from many client systems.

15.1. The logging RHEL system role

With the logging RHEL system role, you can deploy logging configurations on local and remote hosts.

Logging solutions provide multiple ways of reading logs and multiple logging outputs.

For example, a logging system can receive the following inputs:

  • Local files
  • systemd/journal
  • Another logging system over the network

In addition, a logging system can have the following outputs:

  • Logs stored in the local files in the /var/log directory
  • Logs sent to Elasticsearch
  • Logs forwarded to another logging system

With the logging RHEL system role, you can combine the inputs and outputs to fit your scenario. For example, you can configure a logging solution that stores inputs from journal in a local file, whereas inputs read from files are both forwarded to another logging system and stored in the local log files.

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.logging/README.md file
  • /usr/share/doc/rhel-system-roles/logging/ directory
  • RHEL system roles

15.2. Applying a local logging RHEL system role

Prepare and apply an Ansible playbook to configure a logging solution on a set of separate machines. Each machine records logs locally.

Prerequisites

Note

You do not have to have the rsyslog package installed, because the RHEL system role installs rsyslog when deployed.

Procedure

  1. Create a playbook file, for example ~/playbook.yml, with the following content:

    ---
    - name: Deploying basics input and implicit files output
      hosts: managed-node-01.example.com
      roles:
        - rhel-system-roles.logging
      vars:
        logging_inputs:
          - name: system_input
            type: basics
        logging_outputs:
          - name: files_output
            type: files
        logging_flows:
          - name: flow1
            inputs: [system_input]
            outputs: [files_output]
  2. Validate the playbook syntax:

    $ ansible-playbook --syntax-check ~/playbook.yml

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    $ ansible-playbook ~/playbook.yml

Verification

  1. Test the syntax of the /etc/rsyslog.conf file:

    # rsyslogd -N 1
    rsyslogd: version 8.1911.0-6.el8, config validation run...
    rsyslogd: End of config validation run. Bye.
  2. Verify that the system sends messages to the log:

    1. Send a test message:

      # logger test
    2. View the /var/log/messages log, for example:

      # cat /var/log/messages
      Aug  5 13:48:31 <hostname> root[6778]: test

      Where <hostname> is the host name of the client system. Note that the log contains the user name of the user that entered the logger command, in this case root.

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.logging/README.md file
  • /usr/share/doc/rhel-system-roles/logging/ directory

15.3. Filtering logs in a local logging RHEL system role

You can deploy a logging solution which filters the logs based on the rsyslog property-based filter.

Prerequisites

Note

You do not have to have the rsyslog package installed, because the RHEL system role installs rsyslog when deployed.

Procedure

  1. Create a playbook file, for example ~/playbook.yml, with the following content:

    ---
    - name: Deploying files input and configured files output
      hosts: managed-node-01.example.com
      roles:
        - rhel-system-roles.logging
      vars:
        logging_inputs:
          - name: files_input
            type: basics
        logging_outputs:
          - name: files_output0
            type: files
            property: msg
            property_op: contains
            property_value: error
            path: /var/log/errors.log
          - name: files_output1
            type: files
            property: msg
            property_op: "!contains"
            property_value: error
            path: /var/log/others.log
        logging_flows:
          - name: flow0
            inputs: [files_input]
            outputs: [files_output0, files_output1]

    Using this configuration, all messages that contain the error string are logged in /var/log/errors.log, and all other messages are logged in /var/log/others.log.

    You can replace the error property value with the string by which you want to filter.

    You can modify the variables according to your preferences.

  2. Validate the playbook syntax:

    $ ansible-playbook --syntax-check ~/playbook.yml

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    $ ansible-playbook ~/playbook.yml

Verification

  1. Test the syntax of the /etc/rsyslog.conf file:

    # rsyslogd -N 1
    rsyslogd: version 8.1911.0-6.el8, config validation run...
    rsyslogd: End of config validation run. Bye.
  2. Verify that the system sends messages that contain the error string to the log:

    1. Send a test message:

      # logger error
    2. View the /var/log/errors.log log, for example:

      # cat /var/log/errors.log
      Aug  5 13:48:31 hostname root[6778]: error

      Where hostname is the host name of the client system. Note that the log contains the user name of the user that entered the logger command, in this case root.

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.logging/README.md file
  • /usr/share/doc/rhel-system-roles/logging/ directory

15.4. Applying a remote logging solution by using the logging RHEL system role

Follow these steps to prepare and apply a Red Hat Ansible Core playbook to configure a remote logging solution. In this playbook, one or more clients take logs from systemd-journal and forward them to a remote server. The server receives remote input from remote_rsyslog and remote_files and outputs the logs to local files in directories named by remote host names.

Prerequisites

Note

You do not have to have the rsyslog package installed, because the RHEL system role installs rsyslog when deployed.

Procedure

  1. Create a playbook file, for example ~/playbook.yml, with the following content:

    ---
    - name: Deploying remote input and remote_files output
      hosts: managed-node-01.example.com
      roles:
        - rhel-system-roles.logging
      vars:
        logging_inputs:
          - name: remote_udp_input
            type: remote
            udp_ports: [ 601 ]
          - name: remote_tcp_input
            type: remote
            tcp_ports: [ 601 ]
        logging_outputs:
          - name: remote_files_output
            type: remote_files
        logging_flows:
          - name: flow_0
            inputs: [remote_udp_input, remote_tcp_input]
            outputs: [remote_files_output]
    
    - name: Deploying basics input and forwards output
      hosts: managed-node-02.example.com
      roles:
        - rhel-system-roles.logging
      vars:
        logging_inputs:
          - name: basic_input
            type: basics
        logging_outputs:
          - name: forward_output0
            type: forwards
            severity: info
            target: <host1.example.com>
            udp_port: 601
          - name: forward_output1
            type: forwards
            facility: mail
            target: <host1.example.com>
            tcp_port: 601
        logging_flows:
          - name: flows0
            inputs: [basic_input]
            outputs: [forward_output0, forward_output1]
    
    [basic_input]
    [forward_output0, forward_output1]

    Where <host1.example.com> is the logging server.

    Note

    You can modify the parameters in the playbook to fit your needs.

    Warning

    The logging solution works only with the ports defined in the SELinux policy of the server or client system and open in the firewall. The default SELinux policy includes ports 601, 514, 6514, 10514, and 20514. To use a different port, modify the SELinux policy on the client and server systems.

  2. Validate the playbook syntax:

    $ ansible-playbook --syntax-check ~/playbook.yml

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    $ ansible-playbook ~/playbook.yml

Verification

  1. On both the client and the server system, test the syntax of the /etc/rsyslog.conf file:

    # rsyslogd -N 1
    rsyslogd: version 8.1911.0-6.el8, config validation run (level 1), master config /etc/rsyslog.conf
    rsyslogd: End of config validation run. Bye.
  2. Verify that the client system sends messages to the server:

    1. On the client system, send a test message:

      # logger test
    2. On the server system, view the /var/log/<host2.example.com>/messages log, for example:

      # cat /var/log/<host2.example.com>/messages
      Aug  5 13:48:31 <host2.example.com> root[6778]: test

      Where <host2.example.com> is the host name of the client system. Note that the log contains the user name of the user that entered the logger command, in this case root.

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.logging/README.md file
  • /usr/share/doc/rhel-system-roles/logging/ directory

15.5. Using the logging RHEL system role with TLS

Transport Layer Security (TLS) is a cryptographic protocol designed to allow secure communication over the computer network.

As an administrator, you can use the logging RHEL system role to configure a secure transfer of logs using Red Hat Ansible Automation Platform.

15.5.1. Configuring client logging with TLS

You can use an Ansible playbook with the logging RHEL system role to configure logging on RHEL clients and transfer logs to a remote logging system using TLS encryption.

This procedure creates a private key and certificate, and configures TLS on all hosts in the clients group in the Ansible inventory. The TLS protocol encrypts the message transmission for secure transfer of logs over the network.

Note

You do not have to call the certificate RHEL system role in the playbook to create the certificate. The logging RHEL system role calls it automatically.

In order for the CA to be able to sign the created certificate, the managed nodes must be enrolled in an IdM domain.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes are enrolled in an IdM domain.
  • If the logging server you want to configure on the manage node runs RHEL 9.2 or later and the FIPS mode is enabled, clients must either support the Extended Master Secret (EMS) extension or use TLS 1.3. TLS 1.2 connections without EMS fail. For more information, see the TLS extension "Extended Master Secret" enforced Knowledgebase article.

Procedure

  1. Create a playbook file, for example ~/playbook.yml, with the following content:

    ---
    - name: Deploying files input and forwards output with certs
      hosts: managed-node-01.example.com
      roles:
        - rhel-system-roles.logging
      vars:
        logging_certificates:
          - name: logging_cert
            dns: ['localhost', 'www.example.com']
            ca: ipa
        logging_pki_files:
          - ca_cert: /local/path/to/ca_cert.pem
            cert: /local/path/to/logging_cert.pem
            private_key: /local/path/to/logging_cert.pem
        logging_inputs:
          - name: input_name
            type: files
            input_log_path: /var/log/containers/*.log
        logging_outputs:
          - name: output_name
            type: forwards
            target: your_target_host
            tcp_port: 514
            tls: true
            pki_authmode: x509/name
            permitted_server: 'server.example.com'
        logging_flows:
          - name: flow_name
            inputs: [input_name]
            outputs: [output_name]

    The playbook uses the following parameters:

    logging_certificates
    The value of this parameter is passed on to certificate_requests in the certificate RHEL system role and used to create a private key and certificate.
    logging_pki_files

    Using this parameter, you can configure the paths and other settings that logging uses to find the CA, certificate, and key files used for TLS, specified with one or more of the following sub-parameters: ca_cert, ca_cert_src, cert, cert_src, private_key, private_key_src, and tls.

    Note

    If you are using logging_certificates to create the files on the target node, do not use ca_cert_src, cert_src, and private_key_src, which are used to copy files not created by logging_certificates.

    ca_cert
    Represents the path to the CA certificate file on the target node. Default path is /etc/pki/tls/certs/ca.pem and the file name is set by the user.
    cert
    Represents the path to the certificate file on the target node. Default path is /etc/pki/tls/certs/server-cert.pem and the file name is set by the user.
    private_key
    Represents the path to the private key file on the target node. Default path is /etc/pki/tls/private/server-key.pem and the file name is set by the user.
    ca_cert_src
    Represents the path to the CA certificate file on the control node which is copied to the target host to the location specified by ca_cert. Do not use this if using logging_certificates.
    cert_src
    Represents the path to a certificate file on the control node which is copied to the target host to the location specified by cert. Do not use this if using logging_certificates.
    private_key_src
    Represents the path to a private key file on the control node which is copied to the target host to the location specified by private_key. Do not use this if using logging_certificates.
    tls
    Setting this parameter to true ensures secure transfer of logs over the network. If you do not want a secure wrapper, you can set tls: false.
  2. Validate the playbook syntax:

    $ ansible-playbook --syntax-check ~/playbook.yml

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    $ ansible-playbook ~/playbook.yml

Additional resources