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Chapter 1. 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 Red Hat Enterprise Linux 10 in FIPS mode.

To disable FIPS mode, reinstall the system without enabling FIPS mode.

1.1. 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 algorithms and integrity self-tests are some of the mechanisms to ensure a system uses cryptography that meets the requirements of the standard.

RHEL in FIPS mode

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

To enable FIPS mode, 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. Additionally, components that change their algorithm choices based on whether FIPS mode is enabled choose the correct algorithms. For example, LUKS disk encryption uses the PBKDF2 key derivation function (KDF) during installation in FIPS mode, but it chooses the non-FIPS-compliant Argon2 KDF otherwise. Therefore, a non-FIPS installation with disk encryption is either not compliant or potentially unbootable when switched to FIPS mode after the installation.

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.

FIPS mode status

Whether FIPS mode is enabled is determined by the fips=1 boot option on the kernel command line. The system-wide cryptographic policy automatically follows this setting if it is not explicitly set by using the update-crypto-policies --set FIPS command. Systems with a separate partition for /boot additionally require a boot=UUID=<uuid-of-boot-disk> kernel command line argument. The installer performs the required changes when started in FIPS mode.

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.

FIPS in crypto-policies

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 runs 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 10 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 in the FIPS - Federal Information Processing Standards section on the Product compliance Red Hat Customer Portal page.

Additional resources

1.2. 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: 

    $ cat /proc/sys/crypto/fips_enabled
1

Additional resources

1.3. Enabling FIPS mode with RHEL image builder

You can create a customized image and boot a FIPS-enabled RHEL image. Before you compose the image, you must change the value of the fips directive in your blueprint.

Prerequisites

  • You are logged in as the root user or a user who is a member of the weldr group.

Procedure

  1. Create a plain text file in the Tom’s Obvious, Minimal Language (TOML) format with the following content: 

    name = "system-fips-mode-enabled"
description = "blueprint with FIPS enabled "
version = "0.0.1"

[customizations]
fips = true

[[customizations.user]]
name = "admin"
password = "admin"
groups = ["users", "wheel"]

  2. Import the blueprint to the RHEL image builder server: 

    # composer-cli blueprints push <blueprint-name>.toml

  3. List the existing blueprints to check whether the created blueprint is successfully imported and exists: 

    # composer-cli blueprints show <blueprint-name>

  4. Check whether the components and versions listed in the blueprint and their dependencies are valid: 

    # composer-cli blueprints depsolve <blueprint-name>

  5. Build the customized RHEL image: 

    # composer-cli compose start \ <blueprint-name> \ <image-type> \

  6. Review the image status: 

    # composer-cli compose status
…
$ <UUID> FINISHED <date> <blueprint-name> <blueprint-version> <image-type>
…

  7. Download the image: 

    # composer-cli compose image <UUID>

    RHEL image builder downloads the image to the current directory path. The UUID number and the image size are displayed alongside: 

    $ <UUID-image-name.type>: <size> MB

Verification

  1. Log in to the system image with the username and password that you configured in your blueprint.

  2. Check if FIPS mode is enabled: 

    $ cat /proc/sys/crypto/fips_enabled
1

1.4. Enabling FIPS mode by using bootc-image-builder

To create a disk image and enable FIPS mode with the bootc-image-builder or the bootc install to-disk tool, pass the custom Containerfile as an argument when building the image.

Prerequisites

  • You have Podman installed on your host machine.
  • You have virt-install installed on your host machine.
  • You have root access to run the bootc-image-builder tool, and run the containers in --privileged mode, to build the images.

Procedure

  1. Create a Containerfile with the following instructions to enable the fips=1 kernel argument: 

    FROM registry.redhat.io/rhel9/rhel-bootc:latest
# Enable fips=1 kernel argument: https://containers.github.io/bootc/building/kernel-arguments.html
COPY 01-fips.toml /usr/lib/bootc/kargs.d/
# Enable the FIPS crypto policy
# crypto-policies-scripts is not installed by default in RHEL-10
RUN dnf install -y crypto-policies-scripts && update-crypto-policies --no-reload --set FIPS
  2. Create your bootc-compatible base disk images with bootc-image-builder.

1.5. 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 10 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.
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