[Bug 1811295] Re: systemctl daemon-reexec does not update group membership

[Paul Donohue]

I encountered this same issue on Ubuntu 22.04.03 LTS (systemd
249.11-0ubuntu3.11).

After `usermod -a -G <group> <user>`, processes that are spawned or
restarted by systemd user service units do not pick up the new group
(`grep Group /proc/<PID>/status` does not include the new group) until
after the `systemd --user` process is killed using `sudo loginctl
terminate-user <user>` (which logs the user out) or `sudo systemctl
restart user@<UID>.service` (which doesn't log the user out but
effectively breaks the user's session) or something similar.  Neither
`systemctl --user daemon-reload` nor `systemctl --user daemon-reexec`
helps.  There doesn't appear to be any non-disruptive way to pick up the
group change.

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https://bugs.launchpad.net/bugs/1811295

Title:
  systemctl daemon-reexec does not update group membership

Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  On  Ubuntu 16.04.4 LTS  
  using 
  Package: systemd
  Architecture: amd64
  Version: 229-4ubuntu21.10

  Changes the group membership are not picked up by the systemd process
  for a logged-in user or for a user with enable-linger set regardless
  of login status.  Evidently the

    systemctl --user daemon-reexec

  command preserves group membership across the daemon restart. This is
  bad. It means that only a reboot or

    sudo loginctl terminate-user <user>

  will update the group membership to the proper set. Both of those
  things are extreme disruptions for a system/user that runs servers.

  Can systemctl daemon-reexec be made to update group membership for the
  user in the systemd process?

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