[Pkg-shadow-devel] [shadow-maint/shadow] Allow dots (`.`) in user/group names (#34)

Nicolas François nicolas.francois at centraliens.net
Tue Sep 13 00:12:43 UTC 2016


is_valid_name() is one of the functions that varies depending on the

One historical reason for forbidding periods in user/group names is that it
was used by BSD's chown to separate username and groupname.
I could find this reference:

Also any program could have its own regex and reject / accept usernames (I
don't know any standard username regex definition). Although, since much
more relaxed policy have been used for a while (for example on Debian:
allowing periods should be quite safe.

Best Regards,

2016-09-12 13:48 GMT-07:00 Serge E. Hallyn <serge at hallyn.com>:

> Quoting Alec Larsen (notifications at github.com):
> > Is there a technical reason why dots (`.`) are not allowed in user/group
> names?
> >
> > And if not, would a PR to allow them be accepted? It seems like a simple
> enough change to [`is_valid_name` in libmisc/chkname.c](https://
> github.com/shadow-maint/shadow/blob/e6b23e1431d8d798bb3c620bc26557
> ea44a30b98/libmisc/chkname.c#L49).
> Hi,
> this is the kind of thing which seems to me like it should be perfectly
> safe, but for which i suspect there is a strong historical (or even
> current) reason why it's refused.  I'm cc:ing the mailing list so
> hopefully someone less ignorant than I can answer.
> thanks,
> -serge
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