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hb860

Member

Registered: 2014-09-12

Posts: 81

Website

Some PAM issue causes LightDM to fail

In short, LightDM shows me "Failed to authenticate" BEFORE I enter any credentials.
I found the following in the log.

june 21 21:40:16 main systemd[1]: Starting User Manager for UID 620...
june 21 21:40:16 main systemd[565]: pam_nologin(systemd-user:account): conversation failed
june 21 21:40:16 main audit[565]: USER_ACCT pid=565 uid=0 auid=4294967295 ses=4294967295 msg='op=PAM:accounting grantors=? acct="lightdm" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=failed'
june 21 21:40:16 main systemd[565]: PAM failed: Authentication failure
june 21 21:40:16 main systemd[565]: user@620.service: Failed to set up PAM session: Operation not permitted
june 21 21:40:16 main systemd[565]: user@620.service: Failed at step PAM spawning /usr/lib/systemd/systemd: Operation not permitted
june 21 21:40:16 main systemd[1]: user@620.service: Main process exited, code=exited, status=224/PAM
june 21 21:40:16 main systemd[1]: user@620.service: Failed with result 'exit-code'.
june 21 21:40:16 main systemd[1]: Failed to start User Manager for UID 620.
june 21 21:40:16 main audit[1]: SERVICE_START pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=user@620 comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=failed'

This first happened to me on June 10, 2020, and occasionally repeats on my machine.
I didn't change anything related to PAM for years.
I assume that this can be related to systemd.
Any advice is much appreciated. I am running out of ideas what I can do to resolve it.

Last edited by hb860 (2020-06-21 19:48:56)

seth

Member

Registered: 2012-09-03

Posts: 51,213

Re: Some PAM issue causes LightDM to fail

stat /var/run/nologin /etc/nologin

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hb860

Member

Registered: 2014-09-12

Posts: 81

Website

Re: Some PAM issue causes LightDM to fail

Thanks^
Found /var/run/nologin.
However, it is able to reappear.
After digging the log I found out that apcupsd is crashing on boot and affecting the boot process.
This must be cause of the strange PAM behavior.
I have disabled it, and now I will observe how the OS behaves.

Last edited by hb860 (2020-06-22 11:23:18)

hb860

Member

Registered: 2014-09-12

Posts: 81

Website

Re: Some PAM issue causes LightDM to fail

It looks like the issue is now resolved. So it was apcupsd.

seth

Member

Registered: 2012-09-03

Posts: 51,213

Re: Some PAM issue causes LightDM to fail

/etc/apcupsd/apcupsd.conf should configure when to activate nologin - the default seems "disable"?

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

hb860

Member

Registered: 2014-09-12

Posts: 81

Website

Re: Some PAM issue causes LightDM to fail

Unfortunately, it is something else.
The issue made its comeback even with apcupsd disabled.
Investigating...

hb860

Member

Registered: 2014-09-12

Posts: 81

Website

Re: Some PAM issue causes LightDM to fail

It was the following line in /etc/fstab

//1.1.1.1/share                                /mnt/mountpoint       cifs            uid=user,gid=group,workgroup=WORKGROUP,users,noauto,nofail,credentials=/path,iocharset=utf8 ,x-systemd.automount,x-systemd.mount-timeout=30,_netdev      0 0

It wasn't reflected in logs (or I was unable to notice it). It was hard to discover.
I will use some other method to get it mounted automatically. E.g. via a startup script in Xfce.