Tumbleweed - gdm - after successful Login return to login screen again

English Install/Boot/Login
1

I just upgraded Tumbleweed
Now after login as normal(!) user (gdm) after a short the login screen comes back again
If I login as root user, everything works fine, desktop is presented (KDE/lxde)
I created a new user - same effect, no desktop - and login screen again.
I could not find any errors in journal!!!
What can I do??

2

What I would do to see where the issue is:

a) Boot up - when the login screen appears, jump to Virtual Term 1
(i.e., use CTRL ALT F1 … on my laptop, i have to use Ctrl Fn Alt F1)

b) Login in as root and then change to Runlevel 3 (“telinit 3”) (console, no GUI, with networking), then logout as root user.

c) Login as your regular user account … any errors??

d) if no errors, start a KDE gui session by executing “startx”
… any errors???
… does KDE start up and you get your user screen?

3
  • Login as regular user works on terminal
  • Login and startx works as root user
  • startx as normal user does NOT work as normal user (message: no setuid of Xorg - use displaymanager)
  • see above: !! the login as root user into KDE works on GDM !!

This looks to me like some permission problem?!?

4

Ok, I found out:

  • /usr/bin/Xorg set the setuid bit
  • /dev/fb0 set a+rw
    then the startx of some normal user works!
    So it is finally some permission problem - but where and why now??!??!
    On every restart the permissions are reset and opening of windowmanager as normal user will not work.
5

Next info:
/etc/X11/Xwrapper.config is documented to allow setting needed permissions
I created the file and added

  • allowed_users=anybody
  • needs_root_rights=yes
    still permissions are broken :-/
6

I know your are experimenting to corner a problem. But please understand that you are breaking down the security of your system (same with log-in in the GUI as root) and write down what you did so you can undo all those.

7

A couple questions to possibly narrow it down:

Do you use Wayland ?
If yes, at the login screen, switch the choice from Wayland to X11, then log-in.
Any improvement??

Second … do you use NVIDIA for this machine??

8

this machine has NVIDIA, but meanwhile I switched to NOUVEAU

  • I undid the setuid (not useful)
  • I added gdm to video and tty group
    chmod -ag tty gdm
    chmod -ag video gdm
    now login on the terminal and start of KDE is working again!

But when starting VNC viewer to access Login:
Nov 29 13:30:14 monster /usr/libexec/gdm/gdm-x-session[4363]: Fatal server error:
Nov 29 13:30:14 monster /usr/libexec/gdm/gdm-x-session[4363]: (EE) xf86OpenConsole: Cannot open virtual console 2 (Permission denied)

any ideas, which permission may be missing?

9

@t.fruehbeck If using gdm and Wayland, then you need to look at the gdm udev rules as well as the gdm custom.conf

/etc/gdm/custom.conf

# Uncomment the line below to force the login screen to use Xorg
#WaylandEnable=false

cat /usr/lib/udev/rules.d/61-gdm.rules

Depends on your Nvidia gpu… it may be rejected via the udev rule…

10

Final solution:

  • primary use as remote desktop (VNC) workhorse, so no wayland (still?!? :-/)
  • install of xorg-x11-server-wrapper (Xserver SUID Wrapper)
  • wrapper rejected option “nolisten” that was passed hardcoded(!?) by gdm-x-session and I was not able to turn it off by option DisallowTCP or ServerArguments (oh man, what a mess :-/)
  • so switched to lightdm (ugly) - because support of XDMCP (vnc remote connect)
  • install of org. NVIDIA Driver (SUSE-Driver didnt work?!?)
  • in /etc/sysconfig/displaymanager set DISPLAYMANAGER_REMOTE_ACCESS=“yes”

Finally I am back to work after an unpleasant havoc.
Many thanks for your support!
Regards

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