Allow super privileged containers to use RealtimeKit for scheduling

[debarshiray]

Toolbx containers are super privileged containers [1,2], because they use the host's cgroup, IPC, network and PID namespaces, and turn off SELinux label separation. It's likely that users will want to use PipeWire inside Toolbx containers because they need some form of audio or video, and PipeWire needs to be able to use RealtimeKit to change the CPU priority of processes using these D-Bus interfaces:

• org.freedesktop.RealtimeKit1.MakeThreadHighPriorityWithPID
• org.freedesktop.RealtimeKit1.MakeThreadRealtimeWithPID

If the SELinux policy blocks the processes inside super privileged containers from using RealtimeKit, then it will lead to:

  type=AVC msg=audit(1721340769.363:269): avc:  denied  { setsched } for
      pid=762 comm="rtkit-daemon"
      scontext=system_u:system_r:rtkit_daemon_t:s0
      tcontext=unconfined_u:unconfined_r:spc_t:s0 tclass=process
      permissive=0

[1] https://developers.redhat.com/blog/2014/11/06/introducing-a-super-privileged-container-concept

[2] https://danwalsh.livejournal.com/74754.html

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2298800

Summary by Sourcery

Bug Fixes:

• Fixes an issue where SELinux policy blocks processes inside super privileged containers from using RealtimeKit.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request modifies the SELinux policy to allow processes within super privileged containers (specifically those labeled with spc_t) to utilize RealtimeKit for adjusting process scheduling priorities. This is achieved by granting the rtkit_daemon_t domain the necessary permissions to set scheduling parameters for processes running in the spc_t domain.

No diagrams generated as the changes look simple and do not need a visual representation.

File-Level Changes

Change	Details	Files
Allow processes running in super privileged containers to use RealtimeKit for scheduling.	Added a rule to allow the rtkit_daemon_t domain to set scheduling parameters for processes in the spc_t domain.	container.te

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[sourcery-ai]

Hey @debarshiray - I've reviewed your changes - here's some feedback:

Overall Comments:

• It would be helpful to add a comment to the code explaining why this change is necessary.

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

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[debarshiray]

My SELinux knowledge is limited, and this is completely untested. However, there's extensive debugging information in the original bug, and I followed the suggestions from @rhatdan and @zpytela

[rhatdan]

/approve
/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: debarshiray, rhatdan

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

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Needs approval from an approver in each of these files:

• OWNERS [rhatdan]

Approvers can indicate their approval by writing /approve in a comment
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[debarshiray]

Thanks for the review, @rhatdan !

[lsm5]

@debarshiray is it possible to include a bats test for this case, maybe in the toolbox repo such that we could run it here on container-selinux CI?

[debarshiray]

@debarshiray is it possible to include a bats test for this case, maybe in the toolbox repo such that we could run it here on container-selinux CI?

Yes, it should be possible. I will add one. I need to figure out the best way to check for the SELinux denials from the tests.

[lsm5]

/cherrpick rhaos-maint