[Bug 1890177] Re: rsyslogd: file '/dev/console': open error: Permission denied

[Eric Desrochers]

One easy fix would possibly be the following:

# debian/rsyslog.postinst
case "$1" in
    configure)
        adduser --system --group --no-create-home --quiet syslog || true
        adduser syslog adm || true
       +adduser syslog tty || true


I have tested it in a PPA, and it works just fine:

Preparing to unpack .../rsyslog_8.2001.0-1ubuntu1+test2020307b1_amd64.deb ...
Unpacking rsyslog (8.2001.0-1ubuntu1+test2020307b1) over (8.2001.0-1ubuntu1) ...
Setting up rsyslog (8.2001.0-1ubuntu1+test2020307b1) ...
The user `syslog' is already a member of `adm'.
Adding user `syslog' to group `tty' ...
==> Adding user syslog to group tty <==
Done.
Skipping profile in /etc/apparmor.d/disable: usr.sbin.rsyslogd
Processing triggers for man-db (2.9.1-1) ...
Processing triggers for systemd (245.4-4ubuntu3.1) ...


# /etc/group
tty:x:5:syslog

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https://bugs.launchpad.net/bugs/1890177

Title:
  rsyslogd: file '/dev/console': open error: Permission denied

Status in rsyslog package in Ubuntu:
  New
Status in rsyslog source package in Focal:
  New

Bug description:
  The Privilege Drop options ($PrivDrop*) in focal's rsyslog both point
  to 'syslog' for the user and group, and don't match the
  ownership/permission of '/dev/console' generating the following:

  syslog:Aug  3 15:16:58 <HOSTNAME> rsyslogd: file '/dev/console': open
  error: Permission denied [v8.2001.0 try https://www.rsyslog.com/e/2433
  ]

  Looking in Bionic/18.04LTS, '/dev/console' used to be root:syslog[1],
  nowadays it's root:tty[2]

  [1] - Bionic/18.04LTS (Gcloud instance)
  # ls -l /dev/console
  crw--w---- 1 root syslog 5, 1 Aug  3 15:17 /dev/console

  [2] - Focal/20.04LTS (Gcloud instance)
  # ls -l /dev/console
  crw--w---- 1 root tty 5, 1 Aug  3 17:19 /dev/console

  # /etc/rsyslog.conf
  $PrivDropToUser syslog
  $PrivDropToGroup syslog

  ** As a debug exercise I did the following:
  - Cannot reproduce the situation if I intentionally get rid of the PrivDrop* options.
  - Cannot reproduce the situation if I intentionally add 'syslog' user member of 'tty' group.

  Meaning that it's pretty obvious with the above statement that the
  permission denied is caused by the permission/ownership mismatch
  between '/dev/console' 's ownership permission & syslog user
  (PrivDropTo[User|Group]).

  Other bug:
  https://github.com/GoogleCloudPlatform/compute-image-packages/issues/889

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