CentOS Stream 9 – Common Problem 102 – Diagnosis and Fix

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

Services fail to start; ausearch shows AVC denials after a CentOS Stream 9 update.

Environment & Reproduction

Common after kernel, container-selinux, or selinux-policy package upgrades.

Root Cause Analysis

Updated policy tightens contexts that older configs no longer match.

Quick Triage

Run getenforce and ausearch -m AVC -ts recent.

Step-by-Step Diagnosis

Use audit2allow -a to translate denials into policy suggestions.

Solution – Primary Fix

Restore correct contexts with restorecon -Rv on the affected path.

Solution – Alternative Approaches

Generate and load a custom module via audit2allow -M mymod; semodule -i mymod.pp.

Verification & Acceptance Criteria

Service starts and ausearch shows no new denials for 10 minutes.

Rollback Plan

semodule -r mymod removes the custom module; setenforce 0 only as last resort.

Prevention & Hardening

Track policy versions and test in staging before production rollout.

Related Errors & Cross-Refs

Related: container SELinux labels (:Z), MLS confined user issues.

Related tutorial: View the step-by-step tutorial for centos-stream-9.

View all centos-stream-9 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Red Hat ‘Using SELinux’ guide and selinux-policy release notes.