Fix Ubuntu remediation for pam_faillock rules

[mpurg]

Description:

• Fix Ubuntu remediations for pam_faillock rules to correctly position pam_faillock authfail module in modified pam files.
• Fix Ubuntu remediations for pam_faillock rules to add pam_faillock preauth above the Primary block instead of above pam_unix.
• Clean up and add a few more tests.
• This affects rules in Ubuntu 22.04 CIS and Ubuntu 20.04 STIG

Rationale:

• The remediation wrongly positions the pam_faillock authfail module when the pam file contains commented or empty lines, potentially locking the system.
• Placing the pam_faillock preauth module directly above pam_unix interferes with modules from other rules, specifically, pam_pkcs11 in smartcard_pam_enabled.

Example /etc/pam.d/common-auth on Ubuntu 22.04 after remediation:

# here are the per-package modules (the "Primary" block)
auth        required      pam_faillock.so preauth
auth    [success=2 default=ignore]      pam_unix.so nullok
# random user comment 
auth        [default=die]      pam_faillock.so authfail
auth        sufficient      pam_faillock.so authsucc
auth    [success=1 default=ignore]      pam_sss.so use_first_pass
# here's the fallback if no module succeeds
auth    requisite                       pam_deny.so

After fix:

auth        required      pam_faillock.so preauth
# here are the per-package modules (the "Primary" block)
auth    [success=2 default=ignore]      pam_unix.so nullok
# random user comment 
auth    [success=1 default=ignore]      pam_sss.so use_first_pass
auth        [default=die]      pam_faillock.so authfail
auth        sufficient      pam_faillock.so authsucc
# here's the fallback if no module succeeds
auth    requisite                       pam_deny.so

[openshift-ci]

Hi @mpurg. Thanks for your PR.

I'm waiting for a ComplianceAsCode member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[github-actions]

Start a new ephemeral environment with changes proposed in this pull request:

rhel8 (from CTF) Environment (using Fedora as testing environment)

Fedora Testing Environment

Oracle Linux 8 Environment

[codeclimate]

Code Climate has analyzed commit c538c20 and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (50% is the threshold).

This pull request will bring the total coverage in the repository to 58.5% (0.0% change).

View more on Code Climate.

[dodys]

lgtm, thanks!