[PlanetCCRMA] ACL permissions for USB audio devices

[Fernando Lopez-Lezcano]

On Tue, 2009-04-28 at 13:20 +0200, Luis Garrido wrote:
> Hi!
> 
> Recently my USB audio interface has stopped working for my
> unprivileged user, there is some permission stuff going on.
> 
> kompoza at membrillo:~$ ls -l /dev/snd/
> total 0
> crw-rw----+ 1 root root 116, 13 2009-04-28 10:44 controlC0
> crw-rw----+ 1 root root 116,  6 2009-04-28 10:44 controlC1
> crw-rw----  1 root root 116, 17 2009-04-28 12:47 controlC2
> crw-rw----  1 root root 116, 14 2009-04-28 12:47 midiC2D0
> crw-rw----+ 1 root root 116, 12 2009-04-28 10:44 pcmC0D0c
> crw-rw----+ 1 root root 116, 11 2009-04-28 12:46 pcmC0D0p
> crw-rw----+ 1 root root 116, 10 2009-04-28 10:44 pcmC0D1c
> crw-rw----+ 1 root root 116,  9 2009-04-28 10:44 pcmC0D2c
> crw-rw----+ 1 root root 116,  8 2009-04-28 10:44 pcmC0D3c
> crw-rw----+ 1 root root 116,  7 2009-04-28 10:44 pcmC0D4p
> crw-rw----+ 1 root root 116,  5 2009-04-28 10:44 pcmC1D0c
> crw-rw----+ 1 root root 116,  4 2009-04-28 10:44 pcmC1D0p
> crw-rw----  1 root root 116, 16 2009-04-28 12:47 pcmC2D0c
> crw-rw----  1 root root 116, 15 2009-04-28 12:47 pcmC2D0p
> crw-rw----+ 1 root root 116,  3 2009-04-28 10:44 seq
> crw-rw----+ 1 root root 116,  2 2009-04-28 10:44 timer
> 
> See the + sign at the right of the permission list? That means the
> device has an ACL assigned. My integrated ICH6 card devices get that
> ACL, but not the USB devices.
> 
> kompoza at membrillo:~$ getfacl /dev/snd/pcmC0D0c
> getfacl: Removing leading '/' from absolute path names
> # file: dev/snd/pcmC0D0c
> # owner: root
> # group: root
> user::rw-
> user:kompoza:rw-
> group::rw-
> mask::rw-
> other::---
> 
> kompoza at membrillo:~$ getfacl /dev/snd/pcmC
> pcmC0D0c  pcmC0D1c  pcmC0D3c  pcmC1D0c  pcmC2D0c
> pcmC0D0p  pcmC0D2c  pcmC0D4p  pcmC1D0p  pcmC2D0p
> kompoza at membrillo:~$ getfacl /dev/snd/pcmC2D0c
> getfacl: Removing leading '/' from absolute path names
> # file: dev/snd/pcmC2D0c
> # owner: root
> # group: root
> user::rw-
> group::rw-
> other::---
> 
> I am using FC10 and this problem only popped up yesterday, so it might
> have to do with some buggy updated package. Of my latest updates
> initscripts seems the most likely candidate, but it could be some
> dormant bug in another package that just got triggered.
> 
> I don't know who is ultimately responsible for this... udev? hal? gdm?
> ConsoleKit? 

I think in fc10 it is ConsoleKit... and it works through ACL's (Access
Control Lists) so I think the ownership of the devices is irrelevant. 

I don't know what could be wrong...
-- Fernando


> I am tracking it down now, but I would appreciate any
> comments that point me in the right direction.
> 
> And if your USB device stopped working recently, check this out, you
> might be in the same situation.