Bug#1007018: systemd: Creates broken symlink to stub-resolv.conf since v250

[Michael Biebl]

Am 10.03.22 um 16:11 schrieb Arnaud Rebillout:

Package: systemd
Version: 250.3-2
Severity: normal
User: de...@kali.org
Usertags: origin-kali

Dear Maintainer,

Since v250, systemd moved the tmpfiles config for /etc/resolv.conf out
of the file tmpfiles.d/etc.conf and inside a new file
tmpfiles.d/systemd-resolve.conf. Cf:
https://github.com/systemd/systemd/commit/b15f6eae

The Debian package does not install tmpfiles.d/etc.conf, however with
this change it now installs the new file
tmpfiles.d/systemd-resolve.conf. One way to see that:

   +--- (debian stable)
   | # dpkg-query -W | grep '^systemd\s'
   | systemd 247.3-6
   | # grep -rn "resolv\.conf" /usr/lib/tmpfiles.d/
   +---

   +--- (debian unstable)
   | # dpkg-query -W | grep '^systemd\s'
   | systemd 250.3-2
   | # grep -rn "resolv\.conf" /usr/lib/tmpfiles.d/
   | /usr/lib/tmpfiles.d/systemd-resolve.conf:10:L! /etc/resolv.conf - - - - 
../run/systemd/resolve/stub-resolv.conf
   +---

The consequence of this change is that, on boot, if there's no file
/etc/resolv.conf, systemd creates a symlink /etc/resolv.conf ->
../run/systemd/resolve/stub-resolv.conf. However, since systemd-resolved
is not enabled, it's a dead symlink, and DNS resolution is broken.

Of course, on most systems there's already a file /etc/resolv.conf, so
an upgrade of the systemd package is unlikely to cause an issue. However
the problem manifests itself when building new systems (eg. with debos),
on first boot there is no file /etc/resolv.conf, and this dead symlink
effectively breaks the network.

From what I see, I have the impression that this new file

tmpfiles.d/systemd-resolve.conf is shipped in the package by mistake,
and should simply be removed from the package?

There is
https://github.com/systemd/systemd/pull/21317
and to some extent relevant as well
https://github.com/systemd/systemd/issues/21402


Of course the upgrade path is a bit tricky, so I shyed away from doing this.

Michael

Might be, that the only clean solution (at least for Debian) is to split out systemd-resolved into its own subpackage (and move this tmpfile along with it). This sub-package would then enable systemd-resolved by default upon installation.

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