[Bug 1792400] Re: smbd failed in host when both lxd container and host have smbd

[ Christian Ehrhardt ]

To avoid unintended processes to be acted on we should combine that with exec.
Man page:
-p, --pidfile pid-file
Check whether a process has created the file pid-file. Note: using this matching option alone might  cause  unintended  processes  to  be acted on, if the old process terminated without being able to remove the pid-file.

Text would be like:
Let daemon start/stop actions only using --exec use --pidfile as well to avoid affecting or being affected by processed of the same name in containers. Let calls only using pidfile add --exec to avoid acting on processes reusing the PIDs.

There is some detail that I'm not sure it was intended or not and we have to be careful.
- debian/samba.samba-ad-dc.init
- debian/samba.smbd.init
On start they used --exec so they would block if "the other" was running
On stop they used --pidfile (so they only stop their own)
I wondered if that would be an issue, but those two init also share the PIDfile path, so it would not really behave differently after the change.

I opened an MP for review and discussions at [1].
In addition there is a xenial PPA to test from [2].

[1]: https://code.launchpad.net/~paelzer/ubuntu/+source/samba/+git/samba/+merge/355532
[2]: https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/3435

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https://bugs.launchpad.net/bugs/1792400

Title:
  smbd failed in host when both lxd container and host have smbd

Status in samba package in Ubuntu:
  Fix Released
Status in samba source package in Trusty:
  Triaged
Status in samba source package in Xenial:
  Triaged

Bug description:
  Setup: install smbd in host and lxd-container.

  Now restart smbd in host:

  service smbd restart
  All is OK.
  Problem: nmap shows "closed" on ports 139 and 445. And users cannot use smbd server in host.

    ● smbd.service - LSB: start Samba SMB/CIFS daemon (smbd)
     Loaded: loaded (/etc/init.d/smbd; bad; vendor preset: enabled)
     Active: active (exited) since Die 2016-10-18 17:35:23 CEST; 2s ago
       Docs: man:systemd-sysv-generator(8)
    Process: 24218 ExecStop=/etc/init.d/smbd stop (code=exited, status=0/SUCCESS)
    Process: 21980 ExecReload=/etc/init.d/smbd reload (code=exited, status=0/SUCCESS)
    Process: 25190 ExecStart=/etc/init.d/smbd start (code=exited, status=0/SUCCESS)

  Okt 18 17:35:22 speedy systemd[1]: Starting LSB: start Samba SMB/CIFS daemon (smbd)...
  Okt 18 17:35:23 speedy smbd[25190]:  * Starting SMB/CIFS daemon smbd
  Okt 18 17:35:23 speedy smbd[25190]:    ...done.
  Okt 18 17:35:23 speedy systemd[1]: Started LSB: start Samba SMB/CIFS daemon (smbd).

  ps axf | grep smbd:

  25356 pts/2    S+     0:00  |   \_ grep --color=auto smbd
  19915 ?        Ss     0:08      \_ /usr/sbin/smbd -D
  19919 ?        S      0:00          \_ /usr/sbin/smbd -D

  However, netstat -tpln | grep "smbd" returns nothing and also nmap
  shows "closed" on ports 139 and 445.

  Workaround [1]:
  change /etc/init.d/smbd:
   if ! start-stop-daemon --start --quiet --oknodo --exec /usr/sbin/smbd -- -D ; then

  to

   if ! start-stop-daemon --start --quiet --oknodo --pidfile
  /var/run/samba/smbd.pid --exec /usr/sbin/smbd -- -D ; then

  I reported this to:
  https://discuss.linuxcontainers.org/t/samba-in-host-and-container/2523

  apt-cache policy samba
  samba:
    Installed: 2:4.3.11+dfsg-0ubuntu0.16.04.15
    Candidate: 2:4.3.11+dfsg-0ubuntu0.16.04.16
    Version table:
       2:4.3.11+dfsg-0ubuntu0.16.04.16 500
          500 http://de.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
   *** 2:4.3.11+dfsg-0ubuntu0.16.04.15 500
          500 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages
          100 /var/lib/dpkg/status
       2:4.3.8+dfsg-0ubuntu1 500
          500 http://de.archive.ubuntu.com/ubuntu xenial/main amd64 Packages

  1. https://serverfault.com/questions/810544/samba-daemon-does-not-
  work-as-systemd-service-but-works-in-foreground

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