Sound only as root

[Hans]

Hi folks,

I am wondering of an application, which is getting sound only when started as
root. When I start this aapplication as a normal user, sound is not working.

Please note, that generally sound is working as a normal user, only this
application needs root.

Environment:

Debian stable with pipewire, window manager is plasma5 (but every other wm
shows the same problem).

I am in the group "audio".

What might first help, I would like to know, if the settings of /dev/snd/* are
correct:

/dev/snd = root:root , drwxr-xr-x

All others below /dev/snd are set

crw-rw--- = root:audio

Is this correct? If yes, any hints, why this special application will have to
use root right?

This application is a flight sim (X-Plane by Laminar Resaerch), a commercial
product, but if it is a bug in the application, I suppose, they will fix it.
Theire support is very well. However, I want to get sure, that everything is
correct by me, before I blame myself.

Any idea might be well.

Thanks for any help.

Best regards

Hans

[Marco M]

Am Wed, 18 Oct 2023 11:25:51 +0200
schrieb Hans <hans.u...@loop.de>:

> Please note, that generally sound is working as a normal user, only
> this application needs root.

Are you in the group "audio"?
Does the application use PipeWire or PulseAudio?
Check pavucontrol.

[Hans]

Am Mittwoch, 18. Oktober 2023, 12:01:01 CEST schrieb Marco M:

Please read my mail:

--- snip ----

Environment:

Debian stable with pipewire, window manager is plasma5 (but every other wm

shows the same problem).

I am in the group "audio".

What might first help, I would like to know, if the settings of /dev/snd/* are

correct:

/dev/snd = root:root , drwxr-xr-x

All others below /dev/snd are set

crw-rw--- = root:audio

Pipewire has a pulseaudio module. But before I tested with pulseaudio, both showed no difference and no success.

Best

Hans

[to...@tuxteam.de]

On Wed, Oct 18, 2023 at 12:14:33PM +0200, Hans wrote:
> Am Mittwoch, 18. Oktober 2023, 12:01:01 CEST schrieb Marco M:
> Please read my mail:
>
> --- snip ----
>
> Environment:
>

> Debian stable with* pipewire*, window manager is plasma5 (but every other wm
> shows the same problem).
>
> *I am in the group "audio".*

Yes, you stated it in your original post.

> What might first help, I would like to know, if the settings of /dev/snd/* are
> correct:
>
> /dev/snd = root:root , drwxr-xr-x

They look about the same on my box. But note that I still
use ALSA directly.

> All others below /dev/snd are set
>
> crw-rw--- = root:audio

You might try running the application under strace. With
some luck and patience you might spot where it's trying to
do things and failing.

Cheers
--
t

[Greg Wooledge]

On Wed, Oct 18, 2023 at 11:25:51AM +0200, Hans wrote:
> I am in the group "audio".

> correct:
>
> /dev/snd = root:root , drwxr-xr-x
>
> All others below /dev/snd are set
>
> crw-rw--- = root:audio

It would help if you pasted the actual "ls -l" output. Here's mine
for comparison:

unicorn:~$ ls -l /dev/snd
total 0
drwxr-xr-x 2 root root 60 Oct 7 08:49 by-id/
drwxr-xr-x 2 root root 80 Oct 7 08:49 by-path/
crw-rw----+ 1 root audio 116, 10 Oct 7 08:49 controlC0
crw-rw----+ 1 root audio 116, 12 Oct 7 08:49 controlC1
crw-rw----+ 1 root audio 116, 8 Oct 7 08:49 hwC0D0
crw-rw----+ 1 root audio 116, 9 Oct 7 08:49 hwC0D2
crw-rw----+ 1 root audio 116, 3 Oct 7 08:50 pcmC0D0c
crw-rw----+ 1 root audio 116, 2 Oct 7 08:57 pcmC0D0p
crw-rw----+ 1 root audio 116, 4 Oct 7 08:49 pcmC0D2c
crw-rw----+ 1 root audio 116, 5 Oct 7 08:50 pcmC0D3p
crw-rw----+ 1 root audio 116, 6 Oct 7 08:50 pcmC0D7p
crw-rw----+ 1 root audio 116, 7 Oct 7 08:50 pcmC0D8p
crw-rw----+ 1 root audio 116, 11 Oct 7 08:50 pcmC1D0c
crw-rw----+ 1 root audio 116, 1 Oct 7 08:49 seq
crw-rw----+ 1 root audio 116, 33 Oct 7 08:49 timer

You see those "+" signs at the ends of the permission strings? Those
are super important here. When you login to Debian, there's various
black magic that happens with "session" and "seats" and so on. One
of the things involved in that magic is adding your account to the
ACL on the audio devices. For instance,

unicorn:~$ getfacl /dev/snd/hwC0D0
getfacl: Removing leading '/' from absolute path names
# file: dev/snd/hwC0D0
# owner: root
# group: audio
user::rw-
user:greg:rw-
group::rw-
mask::rw-
other::---


If yours isn't doing that, then we have a problem. In fact, the very
first thing I wondered when I read your post was "Is this actually a
Debian system, or is it something like Devuan?" If you've altered the
login stuff, for example by trying to remove systemd, then you might
have broken the session/seat magic that sets up the ACLs.

[to...@tuxteam.de]

On Wed, Oct 18, 2023 at 07:16:32AM -0400, Greg Wooledge wrote:

[...]

> You see those "+" signs at the ends of the permission strings? Those
> are super important here. When you login to Debian, there's various
> black magic that happens with "session" and "seats" and so on. One
> of the things involved in that magic is adding your account to the
> ACL on the audio devices. For instance,

Thanks for that other POV, which is most probably relevant to Hans.

I'm in the happy camp of not needing all those pluses. My laptop
has no seats ;-)

Cheers
--
t

[Hans]

Am Mittwoch, 18. Oktober 2023, 13:16:32 CEST schrieb Greg Wooledge:
Hi Greg,

I get the same results as you got. So it is proven, that my system is in good
condition and everything is well configured. This is an important point for my
search!

And no, this system is pure Debian (except that is been upgraded since many
many years. I believe, the first installation was 2010 or so).

Debian is so stable and reliable, so I did not need change much. Of course
packages are uninstalled during that long time and things also changed (like
alsa, then pulseaudio and now wireplumber / pipewire for example).

And as a carefull user, I purged old configurations (using aptitude purge ~c)

So, this is just clean Debian 12 stable.

Hope, the vendor of the application will also have some hints. Fine is, I am
now sure and it is proven, my system is set correctly. This is an important
point for me.

Thanks for the feedback.

Best

Hans