Dear Maintainer,

once the screensaver (xfce4) worked, the password not worked anymore. Failed with correct password.

use Alt+Ctr+F1 login as lina works. not through screensaver and can't issue the screensaver-command -restart due to it locked.

part of the /var/log/auth.log as following:

Mar  9 20:54:32 Debian xscreensaver[4733]: FAILED LOGIN 2 ON DISPLAY
":0", FOR "lina"
Mar  9 20:54:35 Debian unix_chkpwd[6032]: check pass; user unknown
Mar  9 20:54:46 Debian unix_chkpwd[6033]: check pass; user unknown
Mar  9 20:54:46 Debian unix_chkpwd[6033]: password check failed for user (lina)
Mar  9 20:54:46 Debian xscreensaver[4733]:
pam_unix(xscreensaver:auth): authentication failure; logname= uid=1000
euid=1000 tty=:0.0 ruser= rhost=  user=lina
Mar  9 20:54:48 Debian xscreensaver[4733]: FAILED LOGIN 3 ON DISPLAY
":0", FOR "lina"

Thanks ahead for your time, any further info. you need please feel free to ask.

Best regards,

lina

I just had the same problem on Ubuntu and find that /etc/shadow was in the
root group (bad upgrade?).

Make sure you have the right owner, group and permissions.

$ ls -l /etc/shadow
-rw-r----- 1 root shadow 3180 May 15 16:56 /etc/shadow

This may become a feature request on PAM: on a problem to read /etc/shadow,
log an useful message in syslog instead of 'user unkown'.

Thanks to the #debian IRC and this bug report I finally found out why on
all of my Debian machines I couldn't use gnome-screensaver nor xscreensaver
anymore since Squeeze (and now also a Squeeze installation dist-upgraded to
Wheezy). Someone pointed me to this report.

So yes definitely the error needs to be reported in auth.log and if
possible also returned to the application asking for the check.

What I wanted to add here though is that there must be some application
messing up the permissions. Group "root" on /etc/shadow has happened for me
on various Squeeze machines, including one freshly installed from scratch
just recently. It's definitely not (just) from a messed up upgrade.

Cheers.

I'm experiencing this bug after a fresh install (Debian 7.2.0 i386
xfce).  The error messages included in my /var/log/auth.log are
identical to those posted by lina, and when xscreensaver fails to
authenticate I'm still able to login through a virtual terminal.

I've checked the owner:group and permissions of /etc/shadow and they are
exactly like the ones Sebastien Koechlin said were the right ones.

Does anyone know how to circumvent this issue?


Thanks,
Rui Maciel

Dear Maintainer,

Thanks for this bug report, as after replacing the gnome screensaver with
the xscreensaver I still had a login authentication failure with auth.log
as described in earlier 663227 bug reports. (I am running Sid, Jessie on
AMD64 desktop)

my shadow file had these permissions
-rw------- root root

and changing group to shadow did not solve the problem - it was only after
the group read permission was also added that xscreensaver worked.

Again, thanks!