[Bug 1902236] Autopkgtest regression report (systemd/245.4-4ubuntu3.5)

[Ubuntu SRU Bot]

All autopkgtests for the newly accepted systemd (245.4-4ubuntu3.5) for focal have finished running.
The following regressions have been reported in tests triggered by the package:

prometheus-apache-exporter/0.7.0+ds-1 (arm64)
udisks2/2.8.4-1ubuntu1 (amd64, ppc64el)
munin/2.0.56-1ubuntu1 (arm64)
docker.io/19.03.8-0ubuntu1.20.04.2 (s390x)


Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-
migration/focal/update_excuses.html#systemd

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

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https://bugs.launchpad.net/bugs/1902236

Title:
  Duplicated root and nobody returned by getent on Focal

Status in systemd:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in systemd source package in Focal:
  Fix Committed

Bug description:
  [impact]

  getent password or getent group returns duplicate, false/synthesized,
  entries for root and nobody

  [test case]

  root at lp1902236-f:~# getent passwd | grep root
  root:x:0:0:root:/root:/bin/bash
  root:x:0:0:root:/root:/bin/sh
  root at lp1902236-f:~# getent group | grep root
  root:x:0:
  root:x:0:

  root at lp1902236-f:~# getent passwd | grep nobody
  nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
  nobody:x:65534:65534:nobody:/:/usr/sbin/nologin
  root at lp1902236-f:~# getent group | grep nogroup
  nogroup:x:65534:
  nogroup:x:65534:

  [regression potential]

  any regression would likely result in incorrect results to calls to
  getent or other programs using libnss-systemd

  [scope]

  this is needed only for f

  this was fixed upstream by commit
  9494da41c271bb9519d3484b6016526a72cc6be5 which was included first in
  v246, so this is fixed in g and later already.

  b and earlier doesn't show the duplication.

  [original description]

  * Summary

  systemd's NSS integration causes getent passwd/group to return
  duplicated entries for root/root and nobody/nogroup. The root account
  also gets a different shell (/bin/sh instead of /bin/bash).

  * Steps to reproduce:

  1) create a container
  $ lxc launch images:ubuntu/focal test-nobody
  2) check the root and nobody accounts
  $ lxc exec test-nobody -- getent passwd | grep -E '^(root|nobody):'
  3) check the root and nogroup groups
  $ lxc exec test-nobody -- getent group | grep -E '^(root|nogroup):'

  2 and 3 should report a single entry for each account/group but they
  return dups like this:

  root:x:0:0:root:/root:/bin/bash
  nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
  root:x:0:0:root:/root:/bin/sh
  nobody:x:65534:65534:nobody:/:/usr/sbin/nologin

  * Description

  The problem seems to come from the NSS integration:

  $ lxc exec test-nobody -- grep -wF systemd /etc/nsswitch.conf
  passwd:         files systemd
  group:          files systemd

  as the /etc/passwd and /etc/group file contain no dups:

  $ lxc exec test-nobody -- grep ^nobody: /etc/passwd
  nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
  $ lxc exec test-nobody -- grep ^nogroup: /etc/group
  nogroup:x:65534:

  Removing systemd from /etc/nsswitch.conf indeed removes the dup.

  An alternative way of seeing what systemd adds on top of the flat
  files:

  $ lxc exec test-nobody -- bash -c 'diff -u /etc/passwd <(getent passwd)'
  --- /etc/passwd	2020-10-30 13:07:52.219261001 +0000
  +++ /dev/fd/63	2020-10-30 13:29:38.396928732 +0000
  @@ -24,3 +24,5 @@
   _apt:x:105:65534::/nonexistent:/usr/sbin/nologin
   ubuntu:x:1000:1000::/home/ubuntu:/bin/bash
   systemd-coredump:x:999:999:systemd Core Dumper:/:/usr/sbin/nologin
  +root:x:0:0:root:/root:/bin/sh
  +nobody:x:65534:65534:nobody:/:/usr/sbin/nologin

  $ lxc exec test-nobody -- bash -c 'diff -u /etc/group <(getent group)'
  --- /etc/group	2020-10-30 13:07:52.211261089 +0000
  +++ /dev/fd/63	2020-10-30 13:29:45.892846747 +0000
  @@ -50,3 +50,5 @@
   ubuntu:x:1000:
   ssh:x:111:
   systemd-coredump:x:999:
  +root:x:0:
  +nogroup:x:65534:

  * Additional information

  This bug seems to occur on Focal alone as Bionic and Groovy are not
  affected.

  $ lsb_release -rd
  Description:	Ubuntu 20.04.1 LTS
  Release:	20.04

  $ apt-cache policy base-passwd systemd
  base-passwd:
    Installed: 3.5.47
    Candidate: 3.5.47
    Version table:
   *** 3.5.47 500
          500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages
          100 /var/lib/dpkg/status
  systemd:
    Installed: 245.4-4ubuntu3.2
    Candidate: 245.4-4ubuntu3.2
    Version table:
   *** 245.4-4ubuntu3.2 500
          500 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages
          100 /var/lib/dpkg/status
       245.4-4ubuntu3 500
          500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages

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