linux-kernel - Re: [PATCH] nfs: Fix NFS v4 client handling of MAY_EXEC in nfs

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Message-ID: <4A11F997.5030602@redhat.com>
Date:	Tue, 19 May 2009 08:13:11 +0800
From:	Eugene Teo <eugene@...hat.com>
To:	Frank Filz <ffilzlnx@...ibm.com>
CC:	NFS List <linux-nfs@...r.kernel.org>,
	NFS V4 Mailing List <nfsv4@...ux-nfs.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	security@...nel.org, Trond Myklebust <trond.myklebust@....uio.no>,
	Bruce Fields <bfields@...ldses.org>
Subject: Re: [PATCH] nfs: Fix NFS v4 client handling of MAY_EXEC in 	nfs_permission.

Frank Filz wrote:
> Sorry for the resend, got lkml address wrong...
> 
> The problem is that permission checking is skipped if atomic open is
> possible, but when exec opens a file, it just opens it O_READONLY which
> means EXEC permission will not be checked at that time.
> 
> This problem is observed by the following sequence (executed as root):
> 
> mount -t nfs4 server:/ /mnt4
> echo "ls" >/mnt4/foo
> chmod 744 /mnt4/foo
> su guest -c "mnt4/foo"
> 
> Signed-off-by: Frank Filz <ffilzlnx@...ibm.com>

Tested-by: Eugene Teo <eugeneteo@...nel.sg>

Thanks, Eugene
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