linux-ext4 - Re: [PATCH v8 00/41] Richacls

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Message-ID: <20150928174648.GA3190@fieldses.org>
Date:	Mon, 28 Sep 2015 13:46:48 -0400
From:	"J. Bruce Fields" <bfields@...ldses.org>
To:	Andreas Grünbacher 
	<andreas.gruenbacher@...il.com>
Cc:	Andreas Gruenbacher <agruenba@...hat.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Theodore Ts'o <tytso@....edu>,
	Andreas Dilger <adilger.kernel@...ger.ca>,
	Jeff Layton <jlayton@...chiereds.net>,
	Trond Myklebust <trond.myklebust@...marydata.com>,
	Anna Schumaker <anna.schumaker@...app.com>,
	linux-ext4@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux FS-devel Mailing List <linux-fsdevel@...r.kernel.org>,
	Linux NFS Mailing List <linux-nfs@...r.kernel.org>,
	Linux API Mailing List <linux-api@...r.kernel.org>
Subject: Re: [PATCH v8 00/41] Richacls

On Mon, Sep 28, 2015 at 07:10:06PM +0200, Andreas Grünbacher wrote:
> 2015-09-28 18:35 GMT+02:00 J. Bruce Fields <bfields@...ldses.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 always maps it
> >>   to nobody. That's good enough for mapping the file owner and owning
> >>   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 client
> >>   will translate uids and gids that have no mapping to the string "nobody",
> >>   and the server will reject them.  This problem is not specific to acls.
> >
> > Do you have fixes in mind for these two issues?
> 
> 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 possibility
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.
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