#801869 nvidia-graphics-drivers: setting /dev/nvidia* to root:video 0660 breaks gdm3, sddm, ...

Package:
src:nvidia-graphics-drivers
Source:
nvidia-graphics-drivers
Submitter:
Andreas Beckmann
Date:
2025-08-17 17:48:01 UTC
Severity:
normal
Tags:
#801869#5
Date:
2015-10-15 13:14:39 UTC
From:
To:
Setting the permissions on /dev/nvidia* properly (i.e. root:video 0660)
breaks display managers that use acceleration (e.g. gdm3, sddm).

A workaround is to put the dm's user into the video group
(e.g. adduser Debian-gdm video).

For local users logging into X a session-based membership in the video
group is handled automatically via some consolekit magic (in
nvidia-kernel-common).

This bug went unnoticed for a long time due to wrong permissions
(root:root 0666) being applied by the udev module autoload (see #801598).


Andreas
#801869#18
Date:
2015-10-17 17:05:05 UTC
From:
To:
BTW, how is this issue solved in other distributions? Ubuntu? Any other?
Or are they all using 0666 default permissions?


Andreas
#801869#23
Date:
2015-10-17 21:44:34 UTC
From:
To:
I believe consolekit is deprecated, has this magic been ported to
systemd-logind?

If it has, I don't think it's working quite right - I had to put both
Debian-gdm and my personal account into the video group permanently to
get a GNOME session just now. No magic happening. Consolekit isn't
installed, nothing in the GNOME area seems to depend on it anymore.
#801869#28
Date:
2015-10-18 23:20:45 UTC
From:
To:
Installed Ubuntu 15.10 beta2 on another partition to check. It's
running with 352.

The devices are created with 666 root:root:

$ ls -l /dev/nvidia*
crw-rw-rw- 1 root root 195,   0 Oct 19 00:13 /dev/nvidia0
crw-rw-rw- 1 root root 195, 255 Oct 19 00:13 /dev/nvidiactl

Let me know if you would like to check anything else.

Kind regards,
Luca Boccassi
#801869#33
Date:
2015-10-18 23:39:21 UTC
From:
To:
Can you "break" it with /etc/modprobe.d/nvidia-kernel-common.conf from
Debian? (maybe adjusting the module name... I don't know whether/how
they rename the modules)

I'm getting slightly tempted to 2s/^/#/ ...


Andreas
#801869#38
Date:
2015-10-19 10:54:41 UTC
From:
To:
No. Help needed.

Is there anything consolekit related installed?

* ensure that your user account is *not* in group video (I think the
first user created upon installation may be added to a few more groups
including video ...)
* ensure that Debian-gdm is in group video
* use nvidia-driver from backports (that should load with root:video 0660)

Expected: gdm starts, what about using glx as a user?


Andreas
#801869#43
Date:
2015-10-19 21:53:40 UTC
From:
To:
Yep, that breaks it good. GDM crashes with expected GLX error on Ubuntu
too when the devices are not root:root 666.

Kind regards,
Luca Boccassi
#801869#48
Date:
2015-10-19 22:15:30 UTC
From:
To:
The consolekit package is not installed, and the libck-connector0
library is not installed as well.

My user was in the video group as you guessed, removed.

Added.

Installed, and those are the permissions.

Nope, oopses with usual error :-(

Kind regards,
Luca Boccassi
#801869#53
Date:
2015-10-19 22:46:45 UTC
From:
To:
Hmm, gdm already dies? But hadn't that worked previously (with the
add-to-group-video workaround)?


Andreas
#801869#58
Date:
2015-10-19 23:23:43 UTC
From:
To:
Yes, but not without the user in the video group, hadn't tried that before.

Kind regards,
Luca Boccassi
#801869#63
Date:
2015-10-21 14:44:11 UTC
From:
To:
Control: severity -1 normal
since restricting this to root:video 0660 causes too much trouble.
Therefore downgrading the severity. But we would still be interested in
a working solution with more restricted permissions.


Andreas