Date: Mon, 21 Jan 2013 11:11:23 -0500
To: richard@vdtoorn.nl
Cc: linux-nfs@vger.kernel.org
Subject: Re: Hanging nfs4+krb5 mounts with negative uids?
Message-ID: <20130121161123.GB16357@fieldses.org>
References: <26b3643c253ee306d593bb4b20ff095b.squirrel@vdtoorn.nl>
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In-Reply-To: <26b3643c253ee306d593bb4b20ff095b.squirrel@vdtoorn.nl>
From: "J. Bruce Fields" <bfields@fieldses.org>
Sender: linux-nfs-owner@vger.kernel.org

On Mon, Jan 21, 2013 at 04:07:39PM +0100, richard@vdtoorn.nl wrote:
> Hi all,
> 
> I have a question about nfs-utils. It's about a patch that was submitted,
> way back in 2010, fixing hanging mounts because of a int/uint problem:
> 
> you can read the commit message at:
> http://www.spinics.net/lists/linux-nfs/msg14723.html
> 
> This code gets hit, e.g. with the new debian stable release where
> nfs-kernel-server/nfs-common is upgraded to 1.2.6-3 (or upgrade
> nfs-kernel-server from debian stable to debian unstable). On my nfsv4+krb5
> system, this seems to do exactly the opposite of the patch: not fixing,
> but in fact introducing a hanging mount.
> 
> When I change the code back from unsigned uid's to signed uid's the mount
> works again.

Assuming you're running kernel 3.7--this shoulds like the problem fixed
by kernel commit 621eb19ce1ec.. "svcrpc: Revert "sunrpc/cache.h: replace
simple_strtoul"", which has also been backported to 3.7.3.  Could you
let us know whether applying that patch, or upgrading to 3.7.3, fixes
the problem?

--b.

> 
> Can anyone give me any help understanding why this is, or point me in a
> direction in getting this solved? I very well might have just
> misconfigured my nfsv4 + krb5 system (asking myself why am I getting
> negative uids?)
> 
> Some more information to help debugging:
> 
> 1) I'm running a VM as a kerberos KDC/admin server (debian sid/unstable)
> 2) I'm running a second VM as a nfsv4 server configured to use this
> kerberos VM (debian squeeze/stable)
> 3) All VM's are running linux kernel 3.7 (no modules, crypto stuff
> configured), time is synchronized by ntpdate
> 4) On both the nfs-server as an nfs-client, I can succesfully mount using
> krb5/5i/5p.
> 
> Problem: once I dist-upgrade the nfs-server to unstable where
> nfs-utils=1.2.6-3, the mount hangs as described in debian bug #682709.
> When I delete the newly acquired
> machine credential /tmp/krb5cc_machine_***, and retry the mount, the
> syslog error is the following:
> 
> ERROR: GSS-API: error in gss_acquire_cred(): Unspecified GSS failure.
> Minor code may provide more information - Unknown error
> 
> I have a patch available for 1.2.6-3 (basically the opposite of the
> commit), that works for my environment. Just a few lines, can paste if
> anyone is interested.
> 
> Thanks for the help!
> 
> Richard van den Toorn
> (The Netherlands)
> 
> 
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