Chapter 3. Using system-wide cryptographic policies

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

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

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

Procedure

1. Log in to the RHEL 9 web console.

   For details, 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.

   

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

   

4. Click the Apply and reboot button.

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

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

Procedure

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

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

   The settings specified in the example playbook include the following:

   crypto_policies_policy: FUTURE

   Configures the required cryptographic policy (FUTURE) on the managed node. It can be either the base policy or a base policy with some sub-policies. The specified base policy and sub-policies have to be available on the managed node. The default value is null. It means that the configuration is not changed and the crypto_policies RHEL system role will only collect the Ansible facts.

   crypto_policies_reboot_ok: true

   Causes the system to reboot after the cryptographic policy change to make sure all of the services and applications will read the new configuration files. The default value is false.

   For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-system-roles.crypto_policies/README.md file on the control node.

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

   ---
   - name: Verification
     hosts: managed-node-01.example.com
     tasks:
       - name: Verify active cryptographic policy
         ansible.builtin.include_role:
           name: rhel-system-roles.crypto_policies
       - name: Display the currently active cryptographic policy
         ansible.builtin.debug:
           var: crypto_policies_active

   The settings specified in the example playbook include the following:

   crypto_policies_active

   An exported Ansible fact that contains the currently active policy name in the format as accepted by the crypto_policies_policy variable.

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 active policy on the managed node.