On 04.02.2018 17:25, Michael Biebl wrote:
> Am 03.02.2018 um 14:35 schrieb Sven Hartge:
>> Um 14:00 Uhr am 03.02.18 schrieb Michael Biebl:

>>> The alternative afaics would be, that the daemon writes the pid file as
>>> munin:munin then (or ulog:ulog for the above case).
>> No, this would open a potential DoS vector.
>> Image an attacker gaining access to the munin user. He would then be able
>> to write any PID to the PIDfile and the init system would kill the other
>> process when the munin-node service is stopped/restarted.
> I don't think this applies to systemd though. If the process id listed
> in the pid file is not found in the service cgroup, systemd should not
> kill the process listed in the pid file. I suspect that MainPID will not
> be properly set and systemd will complain about it.

But it applies to SysV-Init. If the init-script does not use
start-stop-daemon correctly to check if the PID in the PIDfile belongs
to the executable to be killed or if the init-script uses some other
method of killing the daemon, it might easily kill a different program.

I know, this is not systemds concern whether other init implementations
behave correctly, but if you change the behaviour of a program because
of a behaviour change in systemd and then break other init systems or
increase the insecurity when used with other init systems because of
this, it will fall back negatively on systemd.


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