fix: correct audit_backlog_limit definition in /etc/default/grub

[kaleal]

Description:

Current xccdf_org.ssgproject.content_rule_grub2_audit_backlog_limit_argument remediation is writing the variable name instead of its value in /etc/default/grub.

root@ubuntu2404:~# oscap xccdf eval \
    --profile xccdf_org.ssgproject.content_profile_cis_level2_server \
    --remediate \
    --rule xccdf_org.ssgproject.content_rule_grub2_audit_backlog_limit_argument \
    /vagrant/build/ssg-ubuntu2404-ds.xml
--- Starting Evaluation ---

Title   Extend Audit Backlog Limit for the Audit Daemon
Rule    xccdf_org.ssgproject.content_rule_grub2_audit_backlog_limit_argument
Result  fail


--- Starting Remediation ---

Title   Extend Audit Backlog Limit for the Audit Daemon
Rule    xccdf_org.ssgproject.content_rule_grub2_audit_backlog_limit_argument
W: oscap: Conversion of the string "$var_audit_backlog_limit" to an integer (64 bits) failed: Invalid argument
W: oscap: Can't compare variable 'oval:ssg-var_audit_backlog_limit:var:1' value = '8192' with collected item entity = '$var_audit_backlog_limit'
W: oscap: Conversion of the string "$var_audit_backlog_limit" to an integer (64 bits) failed: Invalid argument
W: oscap: Can't compare variable 'oval:ssg-var_audit_backlog_limit:var:1' value = '8192' with collected item entity = '$var_audit_backlog_limit'
Result  error

root@ubuntu2404:~# grep "audit_backlog_limit" /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash apparmor=1 security=apparmor audit_backlog_limit=$var_audit_backlog_limit"
GRUB_CMDLINE_LINUX=" apparmor=1 security=apparmor audit_backlog_limit=$var_audit_backlog_limit"

Rationale:

The value for audit_backlog_limit must be 8192 instead of $var_audit_backlog_limit.

root@ubuntu2404:~# grep "audit_backlog_limit" /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash audit_backlog_limit=8192"
GRUB_CMDLINE_LINUX=" audit_backlog_limit=8192"

Review Hints:

root@ubuntu2404:~# oscap xccdf eval \
    --profile xccdf_org.ssgproject.content_profile_cis_level2_server \
    --remediate \
    --rule xccdf_org.ssgproject.content_rule_grub2_audit_backlog_limit_argument \
    /vagrant/build/ssg-ubuntu2404-ds.xml
--- Starting Evaluation ---

Title   Extend Audit Backlog Limit for the Audit Daemon
Rule    xccdf_org.ssgproject.content_rule_grub2_audit_backlog_limit_argument
Result  fail


--- Starting Remediation ---

Title   Extend Audit Backlog Limit for the Audit Daemon
Rule    xccdf_org.ssgproject.content_rule_grub2_audit_backlog_limit_argument
Result  fixed

root@ubuntu2404:~# grep "audit_backlog_limit" /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash audit_backlog_limit=8192"
GRUB_CMDLINE_LINUX=" audit_backlog_limit=8192"

root@ubuntu2404:~# oscap xccdf eval \
    --profile xccdf_org.ssgproject.content_profile_cis_level2_server \
    --rule xccdf_org.ssgproject.content_rule_grub2_audit_backlog_limit_argument \
    /vagrant/build/ssg-ubuntu2404-ds.xml
--- Starting Evaluation ---

Title   Extend Audit Backlog Limit for the Audit Daemon
Rule    xccdf_org.ssgproject.content_rule_grub2_audit_backlog_limit_argument
Result  pass

[openshift-ci]

Hi @kaleal. 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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Details

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[jan-cerny]

I have compared the generated code before and after thsi rpoblem and it seems that now the variables are expended correctly.
The problem doesn't affect RHEL content because that doesn't use this macro and only calls the grub_command macro.