Hi,
I have attached a patch that moves the security credendials that are checked
on an open of a mixer/audio/audioctl device to the particuar audio channel
instead of a device global.
The way the check operation is performed on an audio open is that the
credentials are compared to the first in the list of playing channels.
User noticable changes are that it is not permissible to open /dev/mixer if
another user has audio playing - so it is not possible to interfere with
another users mixer settings.
The super user has access to audio/audioctl/mixer devices at all times.
These changes primarily affect audio when hw.driverN.multiuser=0 although it is
no longer permissible to interfere with the audio_info structures of an audio
channel belonging to another user regardless of the value of
hw.driverN.multiuser.
This should address PR kern/52627 audio_setchan affecting privileged process.
If there are no obections, I'd like to commit this change by this time next
week.
Best regards,
Nat
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