Bugzilla – Bug 305999
Ctrl+Alt+Backspace kills user session during screensaver
Last modified: 2007-08-29 17:59:50 UTC
Scenario: Bob locks his screen (activating the screensaver), steps away from his office, and go grabs a drink. Meanwhile John steps in, sees that the screen is locked, and presses Ctrl+Alt+Backspace which terminates Bob's session. Why is this bad? Bob may have been in the middle of some very important work which is likely now lost! Ctrl+Alt+Backspace should be intercepted by the screensaver so that this situation cannot happen.
Scenaroi: Bob locks his screen (activating the screensaver), steps away from the terminal, and go grabs a drink. Meanwhile he is called away and has to go home, leaving the terminal locked. Two days later john steps in, there is only one terminal unlocked, it hasn't been used for two days, so he decides to kill the session with control-alt-backspace. However the distributors have disabled control-alt-backspace so he cannot do this. Two weeks later all the terminals in the room have screensavers and no-one can use any of them. Point is there are use cases for both, for example at university our terminal room would be completely unusable in a matter of a day or two if we couldn't kill X sessions. There is the "switch user" on the screensaver which allows starting a new session, but those are limited, and machines quickly get slow with 10 X sessions running on them.
By that time, of course, admins will likely have killed the session, but that's their call, and it could be made to require root access. Of course, a cautious (paranoid?) user would save work in progress before locking the screen and grabbing a drink. Judgment call in any case.
ctrl-alt-back is handled directly by X, the so called "Zap" command. There is a setting for DontZap in the xorg.conf file you can add: Section "Serverflags" Option "DontZap" "yes" EndSection But X clients can't do this on its own. It boils down to an X default setting issue then, as discussed in bug 59038. *** This bug has been marked as a duplicate of bug 59038 ***