[Bug 1814124] Re: sshd does not start after update

[Christian Ehrhardt ]

I took a fresh Xenial (daily) as well as a Xenial of the release day and ran the commands:
$ apt-get clean && apt-get autoclean && apt-get autoremove && apt-get update && apt-get upgrade && apt-get dist-upgrade && reboot

Obviously the updated different amounts of packages, but none did break
the permissions of /var/run/sshd.

I wonder if the issue is in the OpenVZ 6 template that you use as that
seems to be the only difference that remains. I wonder if you'd have any
chance to do that in LXD or a KVM Guest as a comparison?

I downloaded the template from [1] and didn't find anythig obvious.

But after all /var/run is actually /run and that is a tmpfs mount - so after a reboot nothing of the former run should be there. It should only contain things created since boot.
I wondered what exactly will recreate that path.

It isn't the service itself as that fails:
  $ systemctl stop sshd
  $ rm -rf /run/sshd/
  $ /usr/sbin/sshd -t
    Missing privilege separation directory: /var/run/sshd
    (The service behaves the same on start, so something else must have created the path)

After a reboot it is there and has the correct permissions.

The old sysV inint script at /etc/init.d/ssh:71 would have done that, but in systemd that should no more run. Here it is created by systemd-tmpfiles:
You should have a file like:

$ cat /usr/lib/tmpfiles.d/sshd.conf
d /var/run/sshd 0755 root root

That will make systemd to prepare the directory as it should be on every
boot.

Maybe something in that regard is broken on your openVZ container or template?
Please check:
1. is /var/run a symlink to /run
2. is /run a tmpfs mount
3. is /usr/lib/tmpfiles.d/sshd.conf existing and has the content I have shown?
4. if /var/run/sshd is not correct boot run `systemd-tmpfiles --create` is it created (or permissions fixed)?

[1]: https://wiki.openvz.org/Download/template/precreated

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https://bugs.launchpad.net/bugs/1814124

Title:
  sshd does not start after update

Status in openssh package in Ubuntu:
  Incomplete

Bug description:
  After processing system update by:
  apt-get clean && apt-get autoclean && apt-get autoremove && apt-get update && apt-get upgrade && apt-get dist-upgrade && reboot

  ssh server stops starting at system boot.

  It starts after doing:
  mkdir /var/run/sshd
  chmod 0755 /var/run/sshd
  service ssh start

  It happens on fresh Ubuntu-16.04 installs on every VPS provide I have
  tested so far.

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: openssh-server 1:7.2p2-4ubuntu2.6
  Uname: Linux 2.6.32-042stab127.2 x86_64
  ApportVersion: 2.20.1-0ubuntu2.18
  Architecture: amd64
  Date: Thu Jan 31 10:18:56 2019
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
  SSHDConfig: Error: command ['/usr/sbin/sshd', '-T'] failed with exit code 255: Missing privilege separation directory: /var/run/sshd
  SourcePackage: openssh
  UpgradeStatus: No upgrade log present (probably fresh install)

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