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Bug 433177 - alsactl wants to read /dev/urandom
Summary: alsactl wants to read /dev/urandom
Status: RESOLVED NEEDINFO
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: SELinux (show other bugs)
Hardware: All Linux
: Normal normal
Assignee: SE Linux Bugs
URL:
Whiteboard: sec-policy
Keywords:
Depends on:
Blocks:
 
Reported: 2012-08-29 16:23 UTC by Sven Vermeulen (RETIRED)
Modified: 2012-10-30 21:21 UTC (History)
0 users

See Also:
Package list:
Runtime testing required: ---


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Description Sven Vermeulen (RETIRED) gentoo-dev 2012-08-29 16:23:59 UTC
As reported on the gentoo-hardened mailinglist [1], it seems that even on non-hardened systems alsactl wants to read the urandom device:

"""
Aug 21 08:45:49 dell-studio kernel: [    8.588561] type=1400
audit(1345538718.587:4): avc:  denied  { read } for  pid=1450
comm="alsactl" name="urandom" dev="tmpfs" ino=3255
scontext=system_u:system_r:alsa_t
tcontext=system_u:object_r:urandom_device_t tclass=chr_file
Aug 21 08:45:49 dell-studio kernel: [    8.588576] type=1400
audit(1345538718.587:6): avc:  denied  { open } for  pid=1450
comm="alsactl" name="urandom" dev="tmpfs" ino=3255
scontext=system_u:system_r:alsa_t
tcontext=system_u:object_r:urandom_device_t tclass=chr_file
Aug 21 08:45:49 dell-studio kernel: [    8.588579] type=1400
audit(1345538718.587:7): avc:  denied  { open } for  pid=1452
comm="alsactl" name="urandom" dev="tmpfs" ino=3255
scontext=system_u:system_r:alsa_t
tcontext=system_u:object_r:urandom_device_t tclass=chr_file
"""

However, in the source code of alsa-utils I see no reference to rand() or srand() and I'm currently too oblivious to what calls would require this access. It is not certain this is causing erroneous behavior as there are other alsa_t related denials. In the end though, no sound device is detected (or pulseaudio can't find it at least).

Reproducible: Always
Comment 1 Sven Vermeulen (RETIRED) gentoo-dev 2012-08-29 16:24:47 UTC
[1] http://thread.gmane.org/gmane.linux.gentoo.hardened/5658
Comment 2 Sven Vermeulen (RETIRED) gentoo-dev 2012-10-30 21:21:11 UTC
I'm missing the proper information to tackle this (including some tests and the error message received).