[pulseaudio-discuss] [PATCH] systemd: disable socket activation for root

[Tanu Kaskinen]

On Wed, 2017-02-08 at 10:06 -0300, Felipe Sateler wrote:
> On 8 February 2017 at 09:36, Tanu Kaskinen <tanuk at iki.fi> wrote:
> > On Fri, 2017-02-03 at 10:17 -0300, Felipe Sateler wrote:
> > > On 3 February 2017 at 05:51, Tanu Kaskinen <tanuk at iki.fi> wrote:
> > > > We disallow autospawning for root, but when using systemd socket
> > > > activation to start pulseaudio, that replaces the autospawning
> > > > mechanism, and there was no similar "root protection" in socket
> > > > activation. This patch disables the socket activation for root.
> > > > 
> > > > Thanks to Felipe Sateler for coming up with the idea of using
> > > > ConditionPathIsReadWrite=!/run.
> > > 
> > > I'm sorry but I'll have to take this back. This check only checks if
> > > the path is mounted read-write, not if the calling process has the
> > > necessary permissions.
> > > 
> > > https://github.com/systemd/systemd/blob/master/src/shared/condition.c#L405
> > > https://github.com/systemd/systemd/blob/master/src/basic/stat-util.c#L126
> > > 
> > > :(
> > 
> > Well, that's disappointing (and shame on me - I should have tested the
> > patch better).
> > 
> > I think using ExecStartPre as Ahmed first suggested is the best
> > solution. It should do exactly what we want. The admin capability check
> > can have some corner cases where it does the wrong thing.
> 
> The ExecStartPre= solution has the undesirable side effect that it
> marks the unit as failed, and thus the systemd --user session as
> degraded. I think the CAP_SYS_ADMIN solution is a bit better until we
> get ConditionUID. Presumably the people running containers where root
> does not have CAP_SYS_ADMIN know what they are doing.

Good point. I'll make v2 with the capability check.

-- 
Tanu

https://www.patreon.com/tanuk