In the xscreensaver man page it says: Enable locking: before the screensaver will turn off, it will require you to type the password of the logged-in user (really, the person who ran xscreensaver), or the root password. When a user is logged in and locks the screen (or it locks automatically after the time out), they can enter their password and unlock with no problem. But if I try to unlock their screen with the root password it doesn't work. So then I have to log in and kill xscreensaver to unlock the screen. This isn't a super-big deal, but I imagine in a public lab, this could be a pain (users leave the screen locked for the afternoon and the sysadmin has to go around killing xscreensavers...) Thanks.
This is a consequence of the screensaver not being setuid root, and the use of shadow passwords.
So, not to waste any more of your time, I can understand how shadow passwords and non-setuid root xscreensaver would cause this problem. But how does one solve it? Make xscreensaver setuid root? Or does that create other problems? Thanks for you time.
*** Bug 76969 has been marked as a duplicate of this bug. ***