Arch Linux

AlexisBRENON

Member

Registered: 2018-09-06

Posts: 4

Session killed when unlocking from xflock4

Hi.

Sometimes, when I unlock my screen (locked with xflock4), my session is killed and I fallback on my lightdm login screen.
Is there a way to find what happens ? I don't find any logfile for xflock or so.

For more context:

I have a new laptop (Thinkpad T14 Gen3 (AMD)) on which I installed Arch with an Xfce environment.
When I close the lid, the system suspends and the screen is locked. When I open it later, I need to enter password (or fingerprint) to unlock my screen.
Sometimes it works well, but sometimes the lock screen seems to disapear as if the fingerprint is valid, but instead of finding back my session with all my apps opened, the session closes itself and I fallback on the LightDM login screen. This is very annoying because ; first, I need to login again ; then I need to reopen all my windows, and restore their placement and my browser tabs (Brave browser says that it was closed unexpectedly).
I don't know where to start to fix this issue.

Kind,
Alexis.

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 77,057

Re: Session killed when unlocking from xflock4

Either the session process or Xorg crashed, check the system journal and Xorg logs.
This has probably nothing to do w/ xflock4 but rather the S3

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AlexisBRENON

Member

Registered: 2018-09-06

Posts: 4

Re: Session killed when unlocking from xflock4

After some tests, I don't think that it's linked to S3.
I managed to trigger this behavior without going to suspend, just running "xflock4" repeatedly.

I suspect that it's linked to the fprintd-grosshack PAM module. It seems that after some failed authentications through fingerprint, if the next one succeed, then the session is killed.
I didn't manage to reproduce the bug if I remove the "pam_fprintd_grosshack.so" from PAM configuration (but as it is quiet random, maybe it's just by chance).

For information, here is how I setup "pam_fprintd_grosshack":

--- system-auth.orig	2023-05-17 09:57:07.701384184 +0200
+++ /etc/pam.d/system-auth	2023-05-17 09:47:33.744734457 +0200
@@ -3,6 +3,7 @@
 auth       required                    pam_faillock.so      preauth
 # Optionally use requisite above if you do not want to prompt for the password
 # on locked accounts.
+auth	   [success=3 default=bad]     pam_fprintd_grosshack.so
 -auth      [success=2 default=ignore]  pam_systemd_home.so
 auth       [success=1 default=bad]     pam_unix.so          try_first_pass nullok
 auth       [default=die]               pam_faillock.so      authfail

Maybe it's not the right setup. But most services configurations are including the system-auth service, so adding it there, I expect fingerprint authentication to be available everywhere.

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 77,057

Re: Session killed when unlocking from xflock4

Did you inspect the system journal?
For pam failures I'd expect the unlocking to fail, but not the session to be killed.

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How to upload text · How to boot w/o GUI · Disable Windows Fast-Start! · Fix your xinitrc