Public bug reported:
I'm currently using tigervnc-server to expose GDM through the xdmcp
protocol.
This setup allows me to login to a remote desktop session using the gdm
choser, and the functionality has been working correctly up until
recently. However, I have noticed a degradation in various aspects of
the system's features since then.
The reproduction:
To run tigervnc, I'm using systemctl socket. It runs following command:
/usr/bin/Xvnc -inetd -query localhost -geometry 1920x1080 -once
-SecurityTypes=None
GDM configuration fragments:
[daemon]
# Uncomment the line below to force the login screen to use Xorg
WaylandEnable=false
---- REDACTED -----
[xdmcp]
Enable=true
I see following problems with setup:
1. Error loop in system logs (journalctl output).
mar 19 11:10:40 pecet systemd[189128]:
snap.snapd-desktop-integration.snapd-desktop-integration.service: Scheduled
restart job, restart counter is at 2031.
mar 19 11:10:41 pecet systemd[189128]: Started
snap.snapd-desktop-integration.snapd-desktop-integration.service - Service for
snap application snapd-desktop-integration.snapd-desktop-integration.
mar 19 11:10:41 pecet kernel: audit: type=1400 audit(1742379041.036:10458):
apparmor="DENIED" operation="open" class="file"
profile="snap-update-ns.snapd-desktop-integration" name="/proc/337348/maps"
pid=337348 comm="5" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
mar 19 11:10:41 pecet snapd-desktop-i[337379]: Failed to do gtk init. Waiting
for a new session with desktop capabilities.
mar 19 11:10:41 pecet kernel: audit: type=1400 audit(1742379041.106:10459):
apparmor="DENIED" operation="create" class="net"
profile="snap.snapd-desktop-integration.snapd-desktop-integration" pid=337379
comm="snapd-desktop-i" family="inet" sock_type="stream" protocol=6
requested="create" denied="create"
mar 19 11:10:41 pecet snapd-desktop-i[337379]: Checking session
/org/freedesktop/login1/session/_354...
mar 19 11:10:41 pecet snapd-desktop-i[337379]: Is a desktop session! Forcing a
reload.
mar 19 11:10:41 pecet snapd-desktop-i[337379]: Checking session
/org/freedesktop/login1/session/c1...
mar 19 11:10:41 pecet snapd-desktop-i[337379]: Loop exited. Forcing reload.
mar 19 11:10:43 pecet systemd[189128]:
snap.snapd-desktop-integration.snapd-desktop-integration.service: Scheduled
restart job, restart counter is at 2032.
mar 19 11:10:43 pecet systemd[189128]: Started
snap.snapd-desktop-integration.snapd-desktop-integration.service - Service for
snap application snapd-desktop-integration.snapd-desktop-integration.
mar 19 11:10:43 pecet kernel: audit: type=1400 audit(1742379043.285:10460):
apparmor="DENIED" operation="open" class="file"
profile="snap-update-ns.snapd-desktop-integration" name="/proc/337412/maps"
pid=337412 comm="5" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
mar 19 11:10:43 pecet kernel: audit: type=1400 audit(1742379043.352:10461):
apparmor="DENIED" operation="create" class="net"
profile="snap.snapd-desktop-integration.snapd-desktop-integration" pid=337444
comm="snapd-desktop-i" family="inet" sock_type="stream" protocol=6
requested="create" denied="create"
mar 19 11:10:43 pecet snapd-desktop-i[337444]: Failed to do gtk init. Waiting
for a new session with desktop capabilities.
mar 19 11:10:43 pecet snapd-desktop-i[337444]: Checking session
/org/freedesktop/login1/session/_354...
mar 19 11:10:43 pecet snapd-desktop-i[337444]: Is a desktop session! Forcing a
reload.
mar 19 11:10:43 pecet snapd-desktop-i[337444]: Checking session
/org/freedesktop/login1/session/c1...
mar 19 11:10:43 pecet snapd-desktop-i[337444]: Loop exited. Forcing reload.
2. I see that some applications doesn't work - eg file selection modal in
firefox. The modal is not rendered, window is "frozen". The error in logs is
following:
mar 19 11:12:06 pecet xdg-desktop-portal-gnome[190442]: MESA: error: Failed to
attach to x11 shm
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: tigervnc-standalone-server 1.13.1+dfsg-2build2
ProcVersionSignature: Ubuntu 6.11.0-19.19~24.04.1-generic 6.11.11
Uname: Linux 6.11.0-19-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.28.1-0ubuntu3.5
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Wed Mar 19 11:02:43 2025
InstallationDate: Installed on 2024-05-22 (301 days ago)
InstallationMedia: Ubuntu 24.04 LTS "Noble Numbat" - Release amd64 (20240424)
ProcEnviron:
LANG=pl_PL.UTF-8
LC_CTYPE=pl_PL.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
SourcePackage: tigervnc
UpgradeStatus: No upgrade log present (probably fresh install)
** Affects: tigervnc (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble
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https://bugs.launchpad.net/bugs/2103594
Title:
Problems with gnome when connecting via TigerVNC XDMCP
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