[MIR] rtkit

[Luke Yelavich]

RealtimeKit is a D-Bus system service that changes the scheduling policy of user processes/threads to SCHED_RR (i.e. realtime scheduling mode) on request. It is intended to be used as a secure mechanism to allow real-time scheduling to be used by normal user processes.

It will be used as a runtime dependency of pulseaudio to allow pulseaudio to get high priority for audio playback.

http://wiki.ubuntu.com/MainInclusionReportRtKit

 affects ubuntu/rtkit
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[Kees Cook (kees)]

CAP_SYS_PTRACE is extremely powerful, and seems to only be used for debugging (reporting which executable was made RT). I would prefer that CAP_SYS_PTRACE was not included in the capabilities for this daemon. I do like that is chroots itself, though.

Additionally, I would prefer that it drop privileges earlier -- it opens syslog, dbus, etc before dropping privs. Can priv-dropping be moved earlier?

[Luke Yelavich (themuso)]

Ok, removing CAP_SYS_PTRACE doesn't break anything when tested, the syslog simply does not contain any details about what process had what privileges dropped etc. As for dropping privileges earlier, it seems that so far as I have tested, this is not possible, due to rtkit requiring the system dbus socket:
rtkit-daemon[585]: Failed to connect to system bus: Failed to connect to socket /var/run/dbus/system_bus_socket: No such file or directory

I am currently not able to see any other way that this can be worked around in the code. If someone else could take a peak and make a suggestion, I'd appreciate it.

Thanks

 affects ubuntu/rtkit
 status new

[Kees Cook (kees)]

With CAP_SYS_PTRACE gone, I'll be happy with it. :) Once uploaded with that fixed, it's a +1 for me. Thanks!

[Martin Pitt (pitti)]

in component-mismatches, promoted