LightDM doesn't handle Lock Screen or Switch Session for GNOME Shell 3.5
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
GNOME Shell |
Fix Released
|
High
|
|||
gnome-shell (Ubuntu) |
Fix Released
|
Low
|
Unassigned | ||
lightdm (Ubuntu) |
Won't Fix
|
Medium
|
Unassigned |
Bug Description
With GNOME Shell 3.5.90, gnome-shell depends on GDM or at least some GDM methods for the lock screen and user switching functionality. With GDM installed and using LightDM, it's possible to log into GNOME Shell. The Switch Session button doesn't do anything. If you lock the screen, you won't be able to unlock it.
It would be great if LightDM could support this so we don't have to try to find an ugly hack to work around it. It would need to work in at least unity-greeter, but it would be cool if the KDE & GTK greeters would work too as they're being shipped by Kubuntu & Xubuntu.
I pushed the gnome-shell packaging updates to https:/
ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: lightdm 1.3.2-0ubuntu3
ProcVersionSign
Uname: Linux 3.5.0-13-generic x86_64
ApportVersion: 2.5.1-0ubuntu2
Architecture: amd64
CheckboxSubmission: 201084ed41ea754
CheckboxSystem: c541d13ea4f205f
Date: Tue Aug 28 14:50:44 2012
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)
Related branches
Changed in gnome-shell: | |
importance: | Unknown → High |
status: | Unknown → New |
tags: | added: regression-release |
Changed in gnome-shell: | |
status: | New → Fix Released |
I'm not going to provide this interface in LightDM due to:
- All other DMs will have the same problem
- The interface is GDM specific
- (as I understand it) It allows a session process to run PAM calls remotely to authenticate. This is questionable security and opposes the design we have in LightDM for the login screen to be the lock screen.
- The interface is not trivial
So the solution as I see it is we will have to patch gnome-shell to handle not running inside GDM. The options are probably.
1. Not entering lock screen if the GDM interface is not present. This means no lock screen but is logical (no point locking if you know you can't unlock).
2. If the GDM interface is not present then falling back to the old gnome-screensaver method of unlocking. This means running the PAM calls yourself to authenticate. You can't authenticate as anyone but yourself and it's always been a bit of a hack (PAM generally assumes root access, the modules handle running as non-root for this case specifically).