Re: Sanity limit for length of user/group names?

Rick Macklem <rmacklem@uoguelph.ca> wrote:
> Ronald Klop <ronald-lists@klop.ws> wrote:
> > Hi,
> >
> > A google search gives me this page: https://forums.freebsd.org/threads/username-length-16.28189/ .
> > It talks about MAXLOGNAME and limits in utmp.
> Yep, I had forgotten about that one.
> However, it is very small (and can be increased for a build) and I think it only applies
> to user names and not group names.
>
> When I look in getgrent.c, the only limit I see is for the entire "struct group", which is
> GRP_STORAGE_MAX, set to 1Mbyte. (1Mbyte seems larger than I would want to set
> the sanity limit to.)
> I'll experiment with a long group name and see what happens, at least for the local
> /etc/group file case.
I just tried a group with a name > 1K and it worked, so it does appear that the only limit
is the 1Mbyte for the entire "struct group", at least for the local /etc/group
file case.

My current patch for the NFSv4 server uses 10K as a sanity limit and maybe I'll
just stick with that.

Thanks, rick

Regards,
Ronald


Van: Rick Macklem <rmacklem@uoguelph.ca>
Datum: 13 april 2022 03:08
Aan: freebsd-current <freebsd-current@freebsd.org>
Onderwerp: Sanity limit for length of user/group names?

Hi,

The NFSv4 RFCs do not specify an upper limit for the length
of a user or group (called Owner/Owner_group in NFSv4) string.

However, PR#260546 notes that a sanity upper limit for their
length is needed.

Is there any constant in FreeBSD that defines the upper limit for
the length of a user or group name?
(I can find the maximum length of a hostname and I think that can
 be used as a safe upper limit for a domain name, as well. The Owner/
 Owner_group names include "@domain" on them.)

Thanks for any help with this, rick

________________________________