From: "J. Bruce Fields" <bfields@fieldses.org>
Subject: Re: [PATCH v8 00/41] Richacls
Date: Mon, 28 Sep 2015 13:46:48 -0400
Message-ID: <20150928174648.GA3190@fieldses.org>
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Cc: Andreas Gruenbacher <agruenba@redhat.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Theodore Ts'o <tytso@mit.edu>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	Jeff Layton <jlayton@poochiereds.net>,
	Trond Myklebust <trond.myklebust@primarydata.com>,
	Anna Schumaker <anna.schumaker@netapp.com>,
	linux-ext4@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
	Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
	Linux API Mailing List <linux-api@vger.kernel.org>
To: Andreas =?utf-8?Q?Gr=C3=BCnbacher?=
	<andreas.gruenbacher@gmail.com>
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On Mon, Sep 28, 2015 at 07:10:06PM +0200, Andreas Gr=C3=BCnbacher wrote=
:
> 2015-09-28 18:35 GMT+02:00 J. Bruce Fields <bfields@fieldses.org>:
> > On Mon, Sep 28, 2015 at 12:08:51AM +0200, Andreas Gruenbacher wrote=
:
> >> Open issues in nfs:
> >>
> >> * When a user or group name cannot be mapped, nfs's idmapper alway=
s maps it
> >>   to nobody. That's good enough for mapping the file owner and own=
ing
> >>   group, but not for identifiers in acls. For now, to get the nfs =
richacl
> >>   support somewhat working, I'm explicitly checking if mapping has=
 resulted
> >>   in uid/gid 99 in the kernel.
> >>
> >> * When the nfs server replies with NFS4ERR_BADNAME for any user or=
 group
> >>   name lookup, the client will stop sending numeric uids and gids =
to the
> >>   server even when the lookup wasn't numeric.  From then on, the c=
lient
> >>   will translate uids and gids that have no mapping to the string =
"nobody",
> >>   and the server will reject them.  This problem is not specific t=
o acls.
> >
> > Do you have fixes in mind for these two issues?
>=20
> I'm not sure how to best fix the idmapper problem, with backwards
> compatibility and all.

I haven't looked at the current nfsidmap interface....  So it's
completely lacking any way to communicate failure?

> The second problem shouldn't be too hard to fix.

Is it enough to turn off the failover in the case there's no possibilit=
y
it could have been caused by a numeric id?

If any user can set ACLs with arbitrary strings as names, then we'd be
giving any user unprivileged user the ability to turn off numeric
idmapping, so I think we need to fix that.

--b.