System reboots and shutdown even if someone is logged in

[Никола Павловић]

The system can be rebooted from login screen even if another user is logged in, this could cause that user to loose changes to open files or cause some other kind of damage.
How to reproduce:
1) Log in to your account
2) Lock screen (CTR+ALT+L)
3) Move the mouse to show password prompt
4) Click "Switch User" - it takes you to lightdm login prompt
5) Click restart in the power menu (upper right corner)
What should happen: lightdm would demand that all users log out before rebooting
What happens: system reboots

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: lightdm 1.8.4-0ubuntu1
ProcVersionSignature: Ubuntu 3.11.0-13.20-generic 3.11.6
Uname: Linux 3.11.0-13-generic x86_64
ApportVersion: 2.12.5-0ubuntu2.1
Architecture: amd64
Date: Sun Nov 10 15:10:58 2013
InstallationDate: Installed on 2013-05-17 (176 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
MarkForUpload: True
SourcePackage: lightdm
UpgradeStatus: Upgraded to saucy on 2013-10-26 (14 days ago)

[Thaddaeus Tintenfisch (thad-fisch-deactivatedaccount)]

What about shutdown/suspend/hibernate? Currently the active user is allowed to reboot the system even if multiple sessions are running.

[Никола Павловић (nikola825)]

Suspend, shutdown and hibernate also work. Shutting down a computer with users logged in is a careless thing to do, those user could loose their work. I remember that GDM didn't allow such action.

[Robert Ancell (robert-ancell)]

Re-assigning to Unity Greeter since LightDM doesn't make any decisions on when the system can be rebooted. This might be related to bug 861171 where you previously couldn't shutdown when users were logged in. The problem lies somewhere in the PolicyKit policy and the ability of Unity Greeter to support needing authorization to shutdown.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.