Date: Thu, 6 Feb 2014 13:36:31 -0500
To: Norman Elton <normelton@gmail.com>
Cc: "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
Subject: Re: Windows AD, Users with too many groups
Message-ID: <20140206183631.GA30952@fieldses.org>
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From: "J. Bruce Fields" <bfields@fieldses.org>
Sender: linux-nfs-owner@vger.kernel.org

On Thu, Feb 06, 2014 at 01:19:19PM -0500, Norman Elton wrote:
> Just a follow-up to my previous post. In debugging rpc.gssd on the
> client, here's where things are dying:
> 
> creating tcp client for server filertest.safety.net.wm.edu
> creating context with server nfs@filertest.safety.net.wm.edu
> WARNING: Failed to create krb5 context for user with uid 30487 for
> server filertest.safety.net.wm.edu
> 
> But other users seem fine. I still think it's something to do with
> excessive group membership.

And they have that same group membership on the server side?

In that case there might be some problem with rpc.svcgssd's handling of
large group lists--some debugging of rpc.svcgssd on the server might be
interesting.

In particular, output from:

	strace -p $(pidof rpc.svcgssd) -s65536 -e trace=open,close,read,write

might be interesting.

--b.

> 
> Any suggestions are appreciated, thanks!
> 
> Norman Elton
> College of William & Mary
> 
> On Mon, Feb 3, 2014 at 4:13 PM, Norman Elton <normelton@gmail.com> wrote:
> > I've read stories about users having too many group memberships. We
> > seem to experience similar symptoms, though the usual tricks don't
> > seem to work.
> >
> > In our case, there is a RHEL6 NFS server feeding multiple RHEL6 NFS
> > clients. This is all NFSv4 with Kerberos. Most users can login fine,
> > but domain admins get a "permission denied" when accessing their
> > NFS-mounted home directory. The most notable commonality is their high
> > number of group memberships.
> >
> > I've tried inflating my group count to greater than 16, my account
> > continues to work fine.
> >
> > We've tried adding "--manage-gids" to rpc.mountd, no luck. Although
> > it's unclear whether this really does anything in a kerberized
> > environment.
> >
> > Any other suggestions? Other debugging tricks?
> >
> > Thanks
> >
> > Norman Elton
> --
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