CNF-21212: RAN Hardening (5.0) - PAM Empty Passwords (H2)

[sebrandon1]

Summary

Adds MachineConfig to remove the nullok option from PAM authentication on both master and worker nodes.

This addresses HIGH severity E8 compliance check rhcos4-e8-no-empty-passwords which requires preventing authentication with empty passwords.

• Deploys the correct RHCOS 9 /etc/pam.d/system-auth with nullok removed
• Uses the actual RHCOS 9 PAM stack (not the broken operator-generated RHEL 8 template)
• Separate master and worker MachineConfig files

Upstream

We have an open PR to fix this in the RHCOS base image so this MachineConfig remediation would no longer be needed:

• coreos/rhel-coreos-config#255 — Disable empty password authentication via authselect without-nullok

We also have an upstream fix for the broken compliance-operator remediation:

• ComplianceAsCode/content#14602 — Fix no_empty_passwords remediation for RHCOS 9

Files

• 75-pam-auth-high-master.yaml
• 75-pam-auth-high-worker.yaml

Verification

After applying to a cluster, verify with:

oc debug node/ -- chroot /host grep nullok /etc/pam.d/system-auth
# Expected: no output (nullok removed)

Compliance scan verification:

oc get compliancecheckresult -n openshift-compliance | grep no-empty-passwords
# Expected: PASS

Jira

• Story: CNF-21212
• Epic: CNF-22573 (RAN Hardening for 5.0)

References

• Hardening group tracker: https://sebrandon1.github.io/compliance-scripts/versions/4.22/groups/H2

[openshift-ci-robot]

@sebrandon1: This pull request references CNF-21212 which is a valid jira issue.

Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the story to target the "5.0.0" version, but no target version was set.

Details

In response to this:

Summary

Adds MachineConfig to remove the nullok option from PAM authentication on both master and worker nodes.

This addresses HIGH severity E8 compliance check rhcos4-e8-no-empty-passwords which requires preventing authentication with empty passwords.

• Deploys the correct RHCOS 9 /etc/pam.d/system-auth with nullok removed
• Uses the actual RHCOS 9 PAM stack (not the broken operator-generated RHEL 8 template)
• Separate master and worker MachineConfig files

Files

• 75-pam-auth-high-master.yaml
• 75-pam-auth-high-worker.yaml

Verification

After applying to a cluster, verify with:

oc debug node/<node> -- chroot /host grep nullok /etc/pam.d/system-auth
# Expected: no output (nullok removed)

Compliance scan verification:

oc get compliancecheckresult -n openshift-compliance | grep no-empty-passwords
# Expected: PASS

Jira

• Story: CNF-21212
• Epic: CNF-22573 (RAN Hardening for 5.0)

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the openshift-eng/jira-lifecycle-plugin repository.

[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: sebrandon1
Once this PR has been reviewed and has the lgtm label, please assign irinamihai for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[coderabbitai]

Warning

Review limit reached

@sebrandon1, we couldn't start this review because you've reached your PR review rate limit.

More reviews will be available in 59 minutes and 59 seconds. Learn how PR review limits work.

Your organization has run out of usage credits. Purchase more in the billing tab.

⌛ How to resolve this issue?

After more reviews become available, a review can be triggered using the @coderabbitai review command as a PR comment. Alternatively, push new commits to this PR.

We recommend that you space out your commits to avoid hitting the rate limit.

🚦 How do rate limits work?

CodeRabbit enforces hourly rate limits for each developer per organization.

Our paid plans include higher PR review limits than trial, open-source, and free plans. In all cases, reviews become available again over time. During sustained high-volume PR review activity, CodeRabbit may temporarily slow when the next review becomes available.

Please see our Fair Usage Limits Policy for further information.

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Enterprise

Run ID: 42402dd6-0de9-4f39-9dd3-2525bda20619

📥 Commits

Reviewing files that changed from the base of the PR and between e408b98 and 881c68d.

📒 Files selected for processing (2)

• telco-ran/configuration/kube-compare-reference/informational/hardening/75-pam-auth-high-master.yaml
• telco-ran/configuration/kube-compare-reference/informational/hardening/75-pam-auth-high-worker.yaml

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[sebrandon1]

Verification Test Results

Tested on cnfdt16 (OCP 4.22, RHCOS 9.8.20260403-0, 3 masters + 2 workers).

Apply: Applied 75-pam-auth-high-{master,worker}.yaml via oc apply.
Wait: MCP rolling update completed on all 5 nodes.
Verify:

$ oc debug node/cnfdt16-master-0 -- chroot /host grep -c nullok /etc/pam.d/system-auth /etc/pam.d/password-auth
/etc/pam.d/system-auth:0
/etc/pam.d/password-auth:0

$ oc debug node/cnfdt16-worker-0 -- chroot /host grep -c nullok /etc/pam.d/system-auth /etc/pam.d/password-auth
/etc/pam.d/system-auth:0
/etc/pam.d/password-auth:0

Result: PASS — nullok removed from both system-auth and password-auth PAM configs on all master and worker nodes.

[sebrandon1]

I'm considering a potential upstream of this PAM Empty Passwords change.

authselect/authselect#94

The upstream authselect allows for the ability to disable empty passwords. I'm discussing what it would mean to disable empty passwords for RHCOS in Slack: https://redhat-internal.slack.com/archives/C08RWRUQ18T/p1778008748582319

[sebrandon1]

Note: we have an upstream PR open to remove nullok from the RHCOS base image directly — coreos/rhel-coreos-config#255. If that lands, this MachineConfig remediation would no longer be needed for new RHCOS builds.

[openshift-ci-robot]

@sebrandon1: This pull request references CNF-21212 which is a valid jira issue.

Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the story to target the "5.0.0" version, but no target version was set.

Details

In response to this:

Summary

Adds MachineConfig to remove the nullok option from PAM authentication on both master and worker nodes.

This addresses HIGH severity E8 compliance check rhcos4-e8-no-empty-passwords which requires preventing authentication with empty passwords.

• Deploys the correct RHCOS 9 /etc/pam.d/system-auth with nullok removed
• Uses the actual RHCOS 9 PAM stack (not the broken operator-generated RHEL 8 template)
• Separate master and worker MachineConfig files

Upstream

We have an open PR to fix this in the RHCOS base image so this MachineConfig remediation would no longer be needed:

• coreos/rhel-coreos-config#255 — Disable empty password authentication via authselect without-nullok

We also have an upstream fix for the broken compliance-operator remediation:

• ComplianceAsCode/content#14602 — Fix no_empty_passwords remediation for RHCOS 9

Files

• 75-pam-auth-high-master.yaml
• 75-pam-auth-high-worker.yaml

Verification

After applying to a cluster, verify with:

oc debug node/ -- chroot /host grep nullok /etc/pam.d/system-auth
# Expected: no output (nullok removed)

Compliance scan verification:

oc get compliancecheckresult -n openshift-compliance | grep no-empty-passwords
# Expected: PASS

Jira

• Story: CNF-21212
• Epic: CNF-22573 (RAN Hardening for 5.0)

References

• Hardening group tracker: https://sebrandon1.github.io/compliance-scripts/versions/4.22/groups/H2

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the openshift-eng/jira-lifecycle-plugin repository.