Forbid user control over ALSA [disable PolicyKit?]

[Christian Svensson]

No, the user is not a member of audio - it has only one group membership and
that is the one with the same name as the username. (kalmar is member of
kalmar).

The user has access to a terminal, firefox and a couple of more apps. The
user should have access to those and perhaps want to install Flash to
firefox.

Currently they can control the volume and such using alsamixer = bad.

I don't want to restrict a couple of programs that "might change the volume"
- i want to make sure they are unable to use /dev/snd/*.

If the user "kalmar" logs in via the "non-X" terminal (tty0-6 ?) they are
completely unable to use anything related to sound. So somewhere X11 is
changing my permissions and I bet it has to do with PolicyKit.

So, again, how do I disable this feature?

Christian "BC" Svensson
Command Systems


On Wed, Jun 17, 2009 at 12:01 AM, Tony Baldwin <photodharma at gmail.com>wrote:

> On Tue, Jun 16, 2009 at 11:44:39PM +0200, Christian Svensson wrote:
> > Hello.
> >
> > I have a server that is running ALSA with MPD. It's essential that the
> users
> > on the server is not allowed to change volume - piece of cake I thought.
> > The server needs to have Xorg running (fluxbox + firefox). I figured it
> was
> > a matter of simply not having the user in the group audio - man was I
> > misstaken!
> >
> > I belive it's PolicyKit that kindly enough changed the permissions on
> > /dev/snd/* to include an ACL-record of the user that logged on.
> > I've spent a few hours googling around, but a solution is nowhere to be
> > found - this is not your every day problem, I'm sure.
> >
> > So please, how would I disable this "feature"?
> >
>
> Yeah...doesn't removing them from group audio render them unable to
> use the soundsystem completely (ie. no sound at all)?
>
> But, if they are just running a terminal with FF running in a flux session,
> how are they altering the volume (you don't have wmix or something in their
> fluxbox slit,
> I assume) ?
> Perhaps my perception is erroneous, but from what you've written, I'm kind
> of assuming that
> users have access to some kind of web terminal only.
> If you have no fluxbox menu item and don't give them access to a terminal
> or fbrun, etc.,
> I don't see how they can find any other software or means to modify the
> volume, especially
> if they are your typical clueless windows user types.
>
> In any case, could you not just alter the permissions of whatever interface
> or software they
> are using to access volume?  Or is it a matter, of them having access to
> necessary plugins
> for FF that are somehow giving them access to the audio volume?
>
> /tony
>
> --
> http://www.photodharma.com
> art & photos | tony baldwin
>
>
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