[systemd-devel] Github systemd issue 6237

[Zbigniew Jędrzejewski-Szmek]

On Wed, Jul 05, 2017 at 08:10:15PM +1000, Michael Chapman wrote:
> On Wed, 5 Jul 2017, Colin Guthrie wrote:
> >Reindl Harald wrote on 04/07/17 19:50:
> >>>When new configuration options are added, the same unit file can
> >>>almost always be used with older systemd, and it'll just warn & ignore
> >>>the parts it doesn't understand. Similarly, various configuration
> >>>options might be unavailable on some architectures and with some
> >>>compilation options. The current behaviour of warn&ignore provides
> >>>for "soft degradation" in those cases.
> >>
> >>frankly a new option on the left side is a completly different thing
> >>than a invalid value - just silently continue with invalid values of
> >>existing options is playing a danergous game in a crucial component like
> >>systemd
> >
> >It's a rare thing :p but I have to agree with you here!
> >
> >I'd say if "User=-notauser" then silently failing and using root is
> >acceptable as per the usual semantics of "- prefix suppresses errors",
> >but "User=notauser" should fail IMO.
> 
> I'm pretty sure you'll find that it does. Specifically, it will fail
> when the child process for the command being executed attempts to
> map the username to a UID.
> 
> The issue being discussed here is that systemd considers "0day" to
> be _syntactically_ invalid for a username. See the
> valid_user_group_name() function in basic/user-util.c.
> 
> (In my opinion, we shouldn't be this restrictive. POSIX permits
> usernames that start with a digit, and just because certain other
> utilities can't deal with them doesn't mean systemd need forbid
> them.)
> 
> So the directive fails the syntactic check for User=, just like
> Zbigniew's example of User="my name is pretty!".
> 
> I do think we ought to have a list of "critical" directives, such
> that any syntactic error in those directives causes the unit load
> state to be "error". For better or worse, people simply don't look
> at logs, so they'll never notice that important directives in their
> units are being ignored.

https://github.com/systemd/systemd/pull/6300

Zbyszek