Bug#1029945: systemd-resolved: resolve fails if /etc/hosts is a symlink (and causes spamming of log)

[Kevin]

Package: systemd-resolved
Version: 252.4-2
Severity: normal
X-Debbugs-Cc: debian at kevinsteen.net

Dear Maintainer,

If /etc/hosts is a symlink, 'resolvectl query' fails to resolve names in the
linked file.
The log is also spammed every 2 seconds with the entry :
  "Failed to open /etc/hosts: Permission denied"
Permissions on the path to the linked file aren't the issue (all world-
readable).

Evidence:

Jan 29 11:12:31 shiny systemd-resolved[41798]: Failed to open /etc/hosts:
Permission denied
Jan 29 11:12:33 shiny systemd-resolved[41798]: Failed to open /etc/hosts:
Permission denied
Jan 29 11:12:35 shiny systemd-resolved[41798]: Failed to open /etc/hosts:
Permission denied
Jan 29 11:12:37 shiny systemd-resolved[41798]: Failed to open /etc/hosts:
Permission denied
Jan 29 11:12:39 shiny systemd-resolved[41798]: Failed to open /etc/hosts:
Permission denied
Jan 29 11:12:41 shiny systemd-resolved[41798]: Failed to open /etc/hosts:
Permission denied
Jan 29 11:12:43 shiny systemd-resolved[41798]: Failed to open /etc/hosts:
Permission denied
Jan 29 11:12:45 shiny systemd-resolved[41798]: Failed to open /etc/hosts:
Permission denied
^C
root at shiny ~ [SIGINT]# ll /etc/hosts
lrwxrwxrwx 1 root root 22 May 23  2022 /etc/hosts -> /home/bob/hfiles/hosts
root at shiny ~# ll -d /home
drwxr-xr-x 1 root root 6 May 22  2022 /home/
root at shiny ~# ll -d /home/bob
drwxr-xr-x 1 bob bob 968 Jan 29 10:48 /home/bob/
root at shiny ~# ll -d /home/bob/hfiles
drwxr-xr-x 1 bob bob 606 Jun 22  2022 /home/bob/hfiles/
root at shiny ~# ll -d /home/bob/hfiles/hosts
-rw-r--r-- 1 bob bob 586 Jun 22  2022 /home/bob/hfiles/hosts

Sincerely
-Kevin


-- System Information:
Debian Release: bookworm/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 6.1.0-1-amd64 (SMP w/8 CPU threads; PREEMPT)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages systemd-resolved depends on:
ii  dbus [default-dbus-system-bus]  1.14.4-1
ii  libc6                           2.36-8
ii  libssl3                         3.0.7-2
ii  libsystemd-shared               252.4-2
ii  systemd                         252.4-2

Versions of packages systemd-resolved recommends:
pn  libnss-myhostname  <none>
pn  libnss-resolve     <none>

Versions of packages systemd-resolved suggests:
ii  policykit-1  122-2
ii  polkitd      122-2

-- no debconf information