[vox-tech] Sound Trouble with trident module

ME vox-tech@lists.lugod.org
Sun, 30 Jun 2002 16:49:12 -0700 (PDT)


On Sun, 30 Jun 2002, David Margolis wrote:
> I've read that this isn't the most secure way to do this, but I don't know
> why sound would necessarly be a security issue (anyone out there pipe in
> if you have an opinion on this)...
> 
> chmod 666 /dev/dsp*
> chmod 666 /dev/audio*
> chmod 666 /dev/mixer*

Side info: One item of security for not doing this is on multi-user
systems; users can sample from the audio devices and record from a
microphone if attached. They can also play audio when remote. Even though
use of the audio group is the preferred/suggested method, I have known
single user systems that were configured in the way you mention above.

> also, for convenience of playing audio cds
> chmod 666 /dev/cdrom* (this one is probably a bad idea if you ever intend
> to have priate files on a cdrom).

Side info:
CDROM could be 444 unless you have RW capabilities. Also, often /dev/cdrom
is set as a symlink to point to your read device. The default for chmod
when applied to symlinks is to apply them to where they are pointing, not
the symlink. They should just be aware of the permissions set to the
device if it ever changed to a fixed disk or zip drive or...

> The other method for dealing with giving sound to users was only
> slightly more involved and I believe it had to do with creating a
> group that had ownership to
> these devices and adding appropriate users to this group.

Many distros come with an Audio group. You can just add yourself to it
along with anyone that should be able to read/write to the audio
devices. Be careful not to go group-happy and add yourself to too many
places; there are (were - things may have changed) static limits to how
many groups a user can belong. 32? 64? Dont recall. It is in the code.

> Dave
> 
> On Sun, 30 Jun 2002, Rusty Minden wrote:
> 
> > I have compiled the trident module and as root it works sound is
> > fine, but as a user it will not work. It has to be a permission
> > thing or perhaps a group membership, but I am not sure.
> >
> > ALi Sound Card (tridentt.o module)
> > I noticed that the /dev/aidio has owner root and group audio should I add
> > myself to the group?
> >
> > Rusty