[pulseaudio-discuss] System mode & SHM

[Raymond Yau]

> > >>>>
> > >>>> it is possible to enable shared memory when pulseaudio is
> > >>>> stared in system mode?
> > >>>
> > >>> Not without recompiling PulseAudio, the relevant code is
> > >>> in src/pulsecore/protocol_native.c, function
> > >>> command_auth:
> > >>>
> > >>> #ifdef HAVE_CREDS
> > >>>
> > >>>       if (do_shm) {
> > >>>
> > >>>           /* Only enable SHM if both sides are owned by
> > >>>           the
> > >>>
> > >>> same * user. This is a security measure because otherwise
> > >>> data * private to the user might leak. */
> > >>>
> > >>>           const pa_creds *creds;
> > >>>           if (!(creds = pa_pdispatch_creds(pd)) ||
> > >>>           getuid() !=
> > >>>
> > >>> creds->uid) do_shm = false;
> > >>>
> > >>>       }
> > >>>
> > >>> #endif
> > >>>
> > >>> Maybe there's more stuff that needs to be changed as well,
> > >>> I don't know.
> > >>
> > >> Ok, so what about adding parameter which force SHM support
> > >> if user/administrator/owner of system want to do that?
> > >
> > > That sounds like a good idea.
> >
> > I'm hesitating. I'm not saying I'm totally against it, but the
> > security implications are somewhat scary - I assume this
> > means you have to open up the shm files to the world, which
> > means all users can spy on each other's audio. The srbchannel
> > shm file will also be writable by all users, so one user can
> > potentially enter commands in another user's stream...
> >
>
> Yes and this is what in some situation I want!
>
> It is useful in case when you have one desktop computer which is
> used by two (or maybe more) trusted persons and each has own
> profile.

Do your desktop have two sound cards or just want to use multi streaming of
hda-intel for two or three users using analog playback, alt analog
playback, digital, analog capture and alt analog capture devices

>
> Or if you have 2 (or more) users (in system) only because some
> crappy applications support only one instance per user (session).

Any example ?
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