bug#56971: greeter user permissions are not enough to talk with seatd

[muradm]

Liliana Marie Prikler <liliana.prikler@ist.tugraz.at> writes:

> block 56971 by 56690 56699
> thanks
>
> Hi muradm,
Hi Liliana,

> Am Donnerstag, dem 04.08.2022 um 12:45 +0300 schrieb muradm:
> > [...] greeter (e.g. gtkgreet) requiring communication
> > with seatd is failing to start, causing "black screen"
> > behavior on active terminal (switching to the other non seatd
> > related terminal is possible, for manual permissions
> > adjustment as workaround).
> >
> > To address this issue, we need more flexible control over
> > seatd user/group, which creates seatd.sock, and greeter user
> > which connects to seatd.sock.
> Okay.
>
> > However, not all greeters require that, so I decided to make
> > more flexible.
> Flexibility for its own sake is not always the right solution. 
> On the
> other hand, looking at the two patches, it appears they are to 
> be used
> in combination?
No, technically they are not strongly dependent on each other,
could be applied one after another in no particular order.
After both are applied, in cooperation they address this issue.

> >  Propsed solutions consists of:
> >
> > * 56690 - gnu: seatd-service-type: Should use seat group.
> > With this change, if seatd-service-type is present in the
> > system configuration, "seat" group will be added, and seatd
> > will run as root/seat. Group is configurable, but default is
> > "seat".
> Why just the group and no user?  Is it not possible to launch 
> seatd as
> non-root?
seatd provides a way for display servers to access input/output 
devices
without having to be root. So seatd it self has to run as root.
When seatd opening socket as root/seat, all members of seat would
be able to communicate with it. Also socket could be opened with
seat/seat for instance, but there is no specific point in doing 
so.
Will be one more unused system user around.
Arch seems to follow similar way, root/seat is ok for socket.
Also will signal that seatd is running as root.

> > * 56699 - gnu: greetd-service-type: Add greeter-extra-groups
> >   config field.
> > With this change, if user wants to use seatd-service-type with
> > greeter requiring seatd.sock, he can add "seat" group to
> > greeter-extra-groups field.
> Note that you still have a TODO on that patch.
That TODO is from the initial commit, it is about cgroup file
system mounting, and totally out of scope of this issue.

> Cheers
Thanks in advance

signature.asc
Description: PGP signature