Mailinglist Archive: yast-devel (55 mails)

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Re: [yast-devel] snapper 0.3.3 fails to accept group in ALLOW_GROUPS
Hi Arvin,

thanks for the fix.

I meanwhile did some more analysis and think that this might have more
scope than just the fix to snapper. It seems that the order of the
groups AND the number of members in the group file matters too. If
getgrnam_r runs across an entry with too many members then any
subsequent entry is answered with an ERANGE error. So even if the group
that is added to ALLOW_GROUPS does not have that many members but is
listed after one that does the error would still occur. I don't think
working around this with MAX_MEMBERS_PER_GROUP in /etc/login.defs is any
better. It is not supported by yast anyway.

So I take away from this that something in getgrnam_r is buggy (or not
documented) when it has to deal with overfull group files. The
getgrnam_r call appears to be using the buffer not just for the returned
members but also for parsing earlier lines. If one is too full it will fail.

Holger

On Sun, Oct 30, 2016 at 09:04:48AM +0100, Holger Jakob wrote:
When I try to add a group to ALLOW_GROUPS in a snapper config file I get
a "invalid group" error.

The issue was tracked down to getgrnam_r().

In snapper-0.3.3/snapper/AppUtil.cc get_group_gid() fails to find GID
when bufsize is too small.

I have a lot of users in a group in /etc/group.

getgrnam_r() fails to return with success. Increasing bufsize from 1024
to 2000 worked. Removing some of the users from the group also helps.

I recommend to do something like described in

http://pubs.opengroup.org/onlinepubs/9699919799/functions/getgrnam.html
Hi Holger,

thanks for the bug report, I have fixed the issue in
https://github.com/openSUSE/snapper/pull/288.

ciao Arvin


--
Holger Jakob



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