linux-kernel - Re: [PATCH 00/25] move handling of setuid/gid bits from VFS into individual setattr functions (RESEND)

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Date:	Fri, 10 Aug 2007 16:47:52 -0400
From:	Jeff Layton <jlayton@...hat.com>
To:	Trond Myklebust <trond.myklebust@....uio.no>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Jeff Layton <jlayton@...hat.com>, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	v9fs-developer@...ts.sourceforge.net, zippel@...ux-m68k.org,
	dhowells@...hat.com, linux-cifs-client@...ts.samba.org,
	codalist@...EMANN.coda.cs.cmu.edu, joel.becker@...cle.com,
	linux-ext4@...r.kernel.org, fuse-devel@...ts.sourceforge.net,
	cluster-devel@...hat.com,
	user-mode-linux-user@...ts.sourceforge.net,
	mikulas@...ax.karlin.mff.cuni.cz, wli@...omorphy.com,
	jffs-dev@...s.com, jfs-discussion@...ts.sourceforge.net,
	ocfs2-devel@....oracle.com, reiserfs-devel@...r.kernel.org,
	bfennema@...con.csc.calpoly.edu, xfs@....sgi.com
Subject: Re: [PATCH 00/25] move handling of setuid/gid bits from VFS into
 individual setattr functions (RESEND)

On Tue, 07 Aug 2007 20:45:34 -0400
Trond Myklebust <trond.myklebust@....uio.no> wrote:
> > - rename something so that unconverted filesystems will reliably fail to
> >   compile?
> > 
> > - leave existing filesystems alone, but add a new
> >   inode_operations.setattr_jeff, which the networked filesytems can
> >   implement, and teach core vfs to call setattr_jeff in preference to
> >   setattr?
> 
> If you really need to know that the filesystem is handling the flags,
> then how about instead having ->setattr() return something which
> indicates which flags it actually handled? That is likely to be a far
> more intrusive change, but it is one which is future-proof.
> 

One thing that we could do here is have notify_change check
attr->ia_valid after the setattr operation returns. If either ATTR_KILL_*
bit is set then BUG(). The helper function already clears those bits
so anything using it should automatically be ok. We'd have to fix
up NFS and a few others that don't implement suid/sgid.

This is not as certain as changing the name of the inode operation. It
would only pop when someone is attempting to change a setuid/setgid
file on these filesystems. Still, it should conceivably catch most if
not all offenders. Would that be sufficient to take care of everyone's
concerns?

-- 
Jeff Layton <jlayton@...hat.com>
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