Rebased the patch on top of systemd 261.3-0ubuntu2 currently in
stonking-proposed.
Attached systemd_261.3-0ubuntu3.debdiff:
- Gracefully handles EPERM/EACCES privilege errors on char and block device
nodes in systemd-tmpfiles (src/tmpfiles/tmpfiles.c).
- Marks static-nodes-permissions.conf entries with 'z-' so permission errors in
unprivileged namespaces are tolerated.
- Closes LP: #2160036 and Debian: #1140336.
Resetting status to New for sponsorship review.
** Description changed:
[ Impact ]
When running sbuild with the unshare backend (e.g. sbuild --run-
autopkgtest with /dev/kvm bind-mounted) or inside unprivileged user
namespaces and containers with bind-mounted device nodes, package
installation fails during udev configuration:
Setting up udev (261~rc4-1) ...
Creating group 'input' with GID 995.
Creating group 'sgx' with GID 994.
Creating group 'clock' with GID 993.
Creating group 'kvm' with GID 992.
Creating group 'render' with GID 991.
fchownat() of /dev/kvm failed: Operation not permitted
dpkg: error processing package udev (--configure):
installed udev package postinst maintainer script subprocess failed with
exit status 73
Exit status 73 corresponds to EX_CANTCREAT from <sysexits.h>. This
failure completely breaks package building in sbuild unshare
environments.
The issue was unmasked by debhelper 14 (dh_installtmpfiles), which removed
the trailing '|| true' fallback from the generated udev.postinst snippet:
systemd-tmpfiles ${DPKG_ROOT:+--root="$DPKG_ROOT"} --create
static-nodes-permissions.conf
In unprivileged user namespaces, device nodes bind-mounted from the host
are owned by IDs outside the namespace mapping or lack write privileges
to inode metadata in the underlying VFS, causing fchownat() and fchmod()
to return EPERM. Previously, systemd-tmpfiles had always returned exit
code 73 on these nodes, but '|| true' masked the failure. With the
fallback removed, udev configuration aborts.
[ Fix ]
1. In src/tmpfiles/tmpfiles.c (fd_set_perms):
When fchmod_opath() or fchownat() returns a privilege error
(ERRNO_IS_PRIVILEGE) on a character or block device node (S_ISCHR / S_ISBLK),
log the failure at debug level and do not abort. Additionally, respect
i->allow_failure (the '-' prefix in tmpfiles.d).
2. In debian/extra/static-nodes-permissions.conf:
Mark static device node entries with the 'z-' action prefix instead of
'z', explicitly allowing systemd-tmpfiles to tolerate permission setting
failures if running in restricted or unprivileged environments.
[ Test Plan ]
1. Reproduction:
- Configure sbuild with unshare backend and /dev/kvm bind mount:
$autopkgtest_opts = ['--', 'unshare', '--release', '%r', '--arch', '%a',
'-b', '/dev/kvm', '/dev/kvm'];
- Trigger a build or install udev within the unshare environment.
- Without fix: udev.postinst fails on fchownat() of /dev/kvm with exit
code 73.
2. Verification:
- - Build systemd source package with systemd_261.2-1ubuntu3.debdiff and
install udev in the test container.
+ - Build systemd source package with systemd_261.3-0ubuntu3.debdiff and
install udev in the test container.
- Run sbuild --run-autopkgtest with unshare and /dev/kvm bind mount.
- udev.postinst completes with exit code 0, unprivileged device nodes are
gracefully skipped, and package configuration succeeds.
- On a standard host with full root privileges, verify that static device
node ownership (root:kvm, root:render) continues to be applied correctly.
[ Where problems could occur ]
The change is scoped to systemd-tmpfiles device node permission handling
and Debian/Ubuntu static-nodes-permissions.conf.
Privilege errors (EPERM, EACCES) are only tolerated on character/block
device nodes or when lines are explicitly prefixed with 'z-'. Regular
files and directories will continue to fail loudly if ownership cannot
be established.
On privileged systems, systemd-tmpfiles will continue to set ownership
normally. Regression risk is very low.
[ Other Info ]
- Debian counterpart: Debian Bug #1140336 (reported by Benjamin Drung).
- Target series: Ubuntu 26.10 (stonking development series).
- - Package: systemd (261.2-1ubuntu3).
- - Debdiff: Attached to bug as systemd_261.2-1ubuntu3.debdiff (type: patch).
Closes LP: #2160036 and Debian: #1140336.
+ - Package: systemd (261.3-0ubuntu3).
+ - Debdiff: Attached to bug as systemd_261.3-0ubuntu3.debdiff (type: patch).
Closes LP: #2160036 and Debian: #1140336.
+ - Rebase: Rebased on top of systemd 261.3-0ubuntu2 from stonking-proposed.
--- [ Original Report ]
Imported from Debian bug http://bugs.debian.org/1140336:
Package: udev
Version: 261~rc4-1
Severity: normal
X-Debbugs-Cc: <email address hidden>
Dear Maintainer,
I am using sbuild with the unshare backend and this config for
autopkgtest:
$autopkgtest_opts = ['--', 'unshare', '--release', '%r', '--arch', '%a',
'-b', '/dev/kvm', '/dev/kvm'];
Running sbuild --run-autopkgtest on the dracut source code started to
fail during package installation:
Setting up udev (261~rc4-1) ...
Creating group 'input' with GID 995.
Creating group 'sgx' with GID 994.
Creating group 'clock' with GID 993.
Creating group 'kvm' with GID 992.
Creating group 'render' with GID 991.
fchownat() of /dev/kvm failed: Operation not permitted
dpkg: error processing package udev (--configure):
- installed udev package postinst maintainer script subprocess failed with
exit status 73
+ old udev package postinst maintainer script subprocess failed with exit
status 73
** Changed in: systemd (Ubuntu)
Status: Incomplete => New
** Patch added: "systemd 261.3-0ubuntu3 rebased debdiff for stonking"
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/2160036/+attachment/6002519/+files/systemd_261.3-0ubuntu3.debdiff
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https://bugs.launchpad.net/bugs/2160036
Title:
udev: fchownat() of /dev/kvm failed: Operation not permitted
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