[gentoo-dev] State of elogind integration and the default +elogind local USE flag on xorg-server.

[Piotr Karbowski]

Hi,

I'd like to discuss here the current state of elogind integration as a
whole, and the follow-up work that is now required, after I've put a
default on local USE flag +elogind on xorg-server while dropping default
suid flag in my commit yesterday.

The motivation on the changes was to follow up the removal of default
+suid that happened in November last years, that sadly had to be
reverted. Now with elogind integration, non-systemd users got all that
they need to run Xorg as a unprivileged user.

The status of xorg-server at this very moment is that it no longer
defaults to be merged with suid, however, now it defaults to +elogind.
This have the following implications:

- User will be prompted that pambase requires +elogind, which is not
enabled by default -- meaning that simple `emerge xorg-server` will
prompt user to add package.use entry. This could be solved by always
having the elogind bits enabled, the same way a gnome-keyring is, so the
pam_elogind.so is used if present. This shouldn't have any negative
effect on for instance systemd users, as systemd cannot be installed at
the same time as elogind.

- systemd users that does not use systemd profiles will be required to
alter package.use or make.conf USE flags definition to drop -elogind
there, as otherwise xorg-server will refuse to be merged due to
at-most-one-of ( elogind systemd ) condition there. However those
systemd users that do use systemd profiles will not run into any things
to do, as systemd's use.mask have elogind there.

- The desktop profiles enables +consolekit, which conflicts with elogind
-- the users of those profiles will need to adjust USE flags.

- OpenRC/non-systemd users are now able to run X without suid, as
elogind is the entity that wraps the SETMASTER, no more "ioctl
permission denied" on starting X as unprivileged user.

After speaking with some of you on #-dev and #-desktop I know that the
opinions on that vary, arguably enabling elogind local USE flag on
xorg-server was somewhat ahead of time, leaving some users in
unfavorable position where the xorg-server installation will require
them to manually modify package.use/make.conf.

Some of the ideas that were pointed on IRC (forgive me if I missed some):

- We should go back to +suid -elogind default.
- We should actually NOT put suid on Xorg if USE="suid elogind" but put
suid bit with USE="suid -elogind".
- We should only ever enable elogind in desktop profiles.

Personally I'd like to stay without enabling suid by default on
xorg-server, as otherwise hardly anyone will ever drop the suid from it,
which would be a big step back. Gentoo tried to drop suid from
xorg-server a handful of times, let's make the current one a final one :)

I'd like to propose doing the following:

- Keywording elogind on missing archs
- Making elogind a global USE flag
- Switching desktop profiles to elogind from consolekit while still
preserving -suid +elogind on xorg-server for those that does not use
desktop profiles (systemd profiles users not affected)
- Making pambase always install the configuration for pam_elogind.so,
the same way it does for pam_gnome_keyring.so at this very moment,
effectively removing elogind USE flag from it.

What do you all think about?

-- Piotr.