linux-kernel - Re: [NFS] [PATCH 2/7] NFS: if ATTR_KILL_S*ID bits are set, then skip mode change

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Date:	Mon, 17 Sep 2007 09:10:47 -0400
From:	Trond Myklebust <trond.myklebust@....uio.no>
To:	Greg Banks <gnb@....com>
Cc:	Jeff Layton <jlayton@...hat.com>, reiserfs-devel@...r.kernel.org,
	linux-kernel@...r.kernel.org, ecryptfs-devel@...ts.sourceforge.net,
	nfs@...ts.sourceforge.net, linux-fsdevel@...r.kernel.org,
	unionfs@...esystems.org, linux-cifs-client@...ts.samba.org
Subject: Re: [NFS] [PATCH 2/7] NFS: if ATTR_KILL_S*ID bits are set, then
	skip mode change

On Sat, 2007-09-15 at 01:43 +1000, Greg Banks wrote:
> On Fri, Sep 14, 2007 at 10:58:38AM -0400, Jeff Layton wrote:
> > If Irix isn't clearing these bits
> > on a write then it might be good to see if they can fix that...
> 
> I think first you'd have to mount a serious argument that it's broken,
> more serious than "it works differently from Linux".

How about: "If IRIX isn't clearing these bits then they're leaving their
customers wide open to all sorts of security issues."

Unless you make the chmod/chgrp atomic with the write, then there will
always be a way for a client to inject data while the setuid/setgid bits
are set: basically, it allows said client to rewrite a setuid/setgid
executable.

We're not fixing this in the client because it isn't fixable on the
client.

Trond

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