In a few moments, SELinux users which have the \~arch KEYWORDS set (either globally or for the SELinux utilities in particular) will notice that the SELinux userspace will upgrade to version 2.4 (release candidate 5 for now). This upgrade comes with a manual step that needs to be performed after upgrade. The information is mentioned as post-installation message of the policycoreutils package, and basically sais that you need to execute:

~# /usr/libexec/selinux/semanage_migrate_store

The reason is that the SELinux utilities expect the SELinux policy module store (and the semanage related files) to be in /var/lib/selinux and no longer in /etc/selinux. Note that this does not mean that the SELinux policy itself is moved outside of that location, nor is the basic configuration file (/etc/selinux/config). It is what tools such as semanage manage that is moved outside that location.

I tried to automate the migration as part of the packages themselves, but this would require the portage_t domain to be able to move, rebuild and load policies, which it can't (and to be honest, shouldn't). Instead of augmenting the policy or making updates to the migration script as delivered by the upstream project, we currently decided to have the migration done manually. It is a one-time migration anyway.

If for some reason end users forget to do the migration, then that does not mean that the system breaks or becomes unusable. SELinux still works, SELinux aware applications still work; the only thing that will fail are updates on the SELinux configuration through tools like semanage or setsebool - the latter when you want to persist boolean changes.

~# semanage fcontext -l
ValueError: SELinux policy is not managed or store cannot be accessed.

~# setsebool -P allow_ptrace on
Cannot set persistent booleans without managed policy.

If you get those errors or warnings, all that is left to do is to do the migration. Note in the following that there is a warning about 'else' blocks that are no longer supported: that's okay, as far as I know (and it was mentioned on the upstream mailinglist as well as not something to worry about) it does not have any impact.

~# /usr/libexec/selinux/semanage_migrate_store
Migrating from /etc/selinux/mcs/modules/active to /var/lib/selinux/mcs/active
Attempting to rebuild policy from /var/lib/selinux
sysnetwork: Warning: 'else' blocks in optional statements are unsupported in CIL. Dropping from output.

You can also add in -c so that the old policy module store is cleaned up. You can also rerun the command multiple times:

~# /usr/libexec/selinux/semanage_migrate_store -c
warning: Policy type mcs has already been migrated, but modules still exist in the old store. Skipping store.
Attempting to rebuild policy from /var/lib/selinux

You can manually clean up the old policy module store like so:

~# rm -rf /etc/selinux/mcs/modules

So... don't worry - the change is small and does not break stuff. And for those wondering about CIL I'll talk about it in one of my next posts.


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