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Walter
Asked: 2020-02-25 14:01:26 +0800 CST

No sound with Chromium on Ubuntu 19.10

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Pulseaudio is running in daemon mode and I am able to play sound through aplay, vlc, etc, so I know sound is working.

The output of dmesg when chromium is running indicates that apparmor is blocking access to the sound device:

[Mon Feb 24 16:54:34 2020] audit: type=1400 audit(1582581275.262:2277): apparmor="DENIED" operation="mkdir" profile="snap.chromium.chromium" name="/run/user/1000/" pid=16304 comm="mkdir" requested_mask="c" denied_mask="c" fsuid=1000 ouid=1000
[Mon Feb 24 16:54:42 2020] audit: type=1400 audit(1582581283.250:2278): apparmor="DENIED" operation="open" profile="snap.chromium.chromium" name="/dev/snd/controlC0" pid=16275 comm="chrome" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
[Mon Feb 24 16:54:42 2020] audit: type=1400 audit(1582581283.618:2279): apparmor="DENIED" operation="open" profile="snap.chromium.chromium" name="/dev/snd/controlC0" pid=16275 comm="chrome" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
[Mon Feb 24 16:54:42 2020] audit: type=1400 audit(1582581283.618:2280): apparmor="DENIED" operation="open" profile="snap.chromium.chromium" name="/dev/snd/controlC0" pid=16275 comm="chrome" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
[Mon Feb 24 16:54:42 2020] audit: type=1400 audit(1582581283.750:2281): apparmor="DENIED" operation="open" profile="snap.chromium.chromium" name="/dev/snd/controlC0" pid=16275 comm="chrome" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
[Mon Feb 24 16:54:42 2020] audit: type=1400 audit(1582581283.750:2282): apparmor="DENIED" operation="open" profile="snap.chromium.chromium" name="/dev/snd/controlC0" pid=16275 comm="chrome" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
[Mon Feb 24 16:58:48 2020] audit: type=1400 audit(1582581529.770:2284): apparmor="DENIED" operation="open" profile="snap.chromium.chromium" name="/dev/snd/controlC0" pid=16275 comm="chrome" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0

I have stopped apparmor via systemctl stop apparmor.

EDIT: #1:

19 processes are in enforce mode.
   /snap/chromium/1036/usr/lib/chromium-browser/chrome (1227) snap.chromium.chromium
   /snap/chromium/1036/usr/lib/chromium-browser/chrome (1622) snap.chromium.chromium
   /snap/chromium/1036/usr/lib/chromium-browser/chrome (1633) snap.chromium.chromium
   /snap/chromium/1036/usr/lib/chromium-browser/chrome (1686) snap.chromium.chromium
   /snap/chromium/1036/usr/lib/chromium-browser/chrome (1690) snap.chromium.chromium
   /snap/chromium/1036/usr/lib/chromium-browser/chrome (3354) snap.chromium.chromium
   /snap/chromium/1036/usr/lib/chromium-browser/chrome (12295) snap.chromium.chromium
   /snap/chromium/1036/usr/lib/chromium-browser/chrome (12414) snap.chromium.chromium
   /snap/chromium/1036/usr/lib/chromium-browser/chrome (16471) snap.chromium.chromium
   /snap/chromium/1036/usr/lib/chromium-browser/chrome (17290) snap.chromium.chromium
   /snap/chromium/1036/usr/lib/chromium-browser/chrome (20617) snap.chromium.chromium
   /snap/chromium/1036/usr/lib/chromium-browser/chrome (22088) snap.chromium.chromium
   /snap/chromium/1036/usr/lib/chromium-browser/chrome (23416) snap.chromium.chromium

I have omitted irrelevant processes. The chromium snap is in enforce mode.

I don't believe the problem to be with pulseaudio, but instead with the configuration of the chromium snap. It is apparently blocking access to the sound device as indicated by the logs above.

pulseaudio chromium apparmor

2 Answers

  1. Apparmor protects linux services and have two types of profile modes: enforce and complain. In the complain mode, system doesn’t enforce any rules. It will only log the violation attempts

    So you could check what profile mode applied to your daemon:

    $ sudo apt-get install apparmor-utils
$ sudo apparmor_status

    You need to add your pulseaudio daemon into complain mode using aa-complain command:

    $ sudo aa-complain /usr/bin/pulseaudio # path to your daemon could be different

    Use whereis pulseaudio command to see where it is located in your system if path is not displayed in case of apparmor_status command execution.

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  2. Best Answer

    I have temporarily disabled the apparmor profiles via:

    1. running apparmor_parser -R <path to profile>
    2. permanently disabling profile via symlinking <path to profile> /etc/apparmor.d/disable/<profile-to-disable>
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