I recently encountered what is likely the same bug. The directory /var/lib/gdm had the correct permissions gdm:gdm, but all the files inside had something like 973:gdm
a43e9157ef479e94c19951cc9d228cf153bf78ee is supposed to fix this (duplicate bug 37423) but it only checks the permissions of /var/lib/gdm/ itself. Not all of the files in it. This explains why in my case it failed to fix the permissions, because the directory was gdm:gdm. How it got that way I don't know, and infact it doesn't really matter. The directory is mutable, and thus can theoretically be changed for any number of reasons. Therefore if we wish for Guix to be robust with it's Functional design, and have meaningful rollbacks, we perhaps have no choice but to assert the required invariants like these on mutable files. A better solution may be to make it fully chown -R on reconfigure, but not each time on boot? I've attached an untested patch with a suggested solution of making %gdm-activation operate every single time, instead of just after checking /var/lib/gdm.
From 31cb6dbd756af695bd6a1f4d4c89b42367b13307 Mon Sep 17 00:00:00 2001 From: Brendan Tildesley <m...@brendan.scot> Date: Tue, 13 Apr 2021 23:04:28 +1000 Subject: [PATCH] services: gdm: Correctly set ownership on /var/lib/gdm. * gnu/services/xorg.scm (%gdm-activation): Always chown /var/lib/gdm, instead of only when it appears to be correct, because it's still possible the files inside could be wrong and break GDM. I encountered this once: https://issues.guix.gnu.org/36508 . Perhaps it is with good intentions to try not running this code every single time on boot, but when it fails, the consequence is that GDM can break not just for the current revision, but all previous rollback systems in GRUB will fail, and subsequent reconfigure-ings fail too. That totally destroys a desktop system and our rollback functionally, which is much much worse! --- gnu/services/xorg.scm | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff --git a/gnu/services/xorg.scm b/gnu/services/xorg.scm index 17d983ff8d..a206c7c93a 100644 --- a/gnu/services/xorg.scm +++ b/gnu/services/xorg.scm @@ -861,16 +861,11 @@ the GNOME desktop environment.") (let* ((gdm (getpwnam "gdm")) (uid (passwd:uid gdm)) - (gid (passwd:gid gdm)) - (st (stat "/var/lib/gdm" #f))) - ;; Recurse into /var/lib/gdm only if it has wrong ownership. - (when (and st - (or (not (= uid (stat:uid st))) - (not (= gid (stat:gid st))))) - (for-each (lambda (file) - (chown file uid gid)) - (find-files "/var/lib/gdm" - #:directories? #t))))))) + (gid (passwd:gid gdm))) + (for-each (lambda (file) + (chown file uid gid)) + (find-files "/var/lib/gdm" + #:directories? #t)))))) (define dbus-daemon-wrapper (program-file -- 2.31.1
