linux-kernel - [PATCH] knfsd: Fix stale file handle problem with subtree

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Message-Id:  <1060728094255.7278@suse.de>
Date:	Fri, 28 Jul 2006 19:42:55 +1000
From:	NeilBrown <neilb@...e.de>
To:	Andrew Morton <akpm@...l.org>
Cc:	nfs@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: [PATCH] knfsd: Fix stale file handle problem with subtree_checking.

The following patch fixes a bug that was introduced since 2.6.17,
and should go in 2.6.18.

### Comments for Changeset

A recent patch:

  h=7fc90ec93a5eb71f4b08403baf5ba7176b3ec6b1

moved the call to nfsd_setuser out of the 'find a dentry for a
filehandle' branch of fh_verify so that it would always be called.

This had the unfortunately side-effect of moving *after* the call
to decode_fh, so the prober fsuid was not set when nfsd_acceptable
was called, the 'permission' check did the wrong thing.

This patch moves the nfsd_setuser call back where it was, and add as
call in the other branch of the if.

Cc: "J. Bruce Fields" <bfields@...ldses.org>
Signed-off-by: Neil Brown <neilb@...e.de>

### Diffstat output
 ./fs/nfsd/nfsfh.c |   20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff .prev/fs/nfsd/nfsfh.c ./fs/nfsd/nfsfh.c
--- .prev/fs/nfsd/nfsfh.c	2006-07-28 19:14:17.000000000 +1000
+++ ./fs/nfsd/nfsfh.c	2006-07-28 19:14:36.000000000 +1000
@@ -187,6 +187,11 @@ fh_verify(struct svc_rqst *rqstp, struct
 			goto out;
 		}

+		/* Set user creds for this exportpoint */
+		error = nfserrno(nfsd_setuser(rqstp, exp));
+		if (error)
+			goto out;
+
 		/*
 		 * Look up the dentry using the NFS file handle.
 		 */
@@ -241,16 +246,17 @@ fh_verify(struct svc_rqst *rqstp, struct
 		dprintk("nfsd: fh_verify - just checking\n");
 		dentry = fhp->fh_dentry;
 		exp = fhp->fh_export;
+		/* Set user creds for this exportpoint; necessary even
+		 * in the "just checking" case because this may be a
+		 * filehandle that was created by fh_compose, and that
+		 * is about to be used in another nfsv4 compound
+		 * operation */
+		error = nfserrno(nfsd_setuser(rqstp, exp));
+		if (error)
+			goto out;
 	}
 	cache_get(&exp->h);

-	/* Set user creds for this exportpoint; necessary even in the "just
-	 * checking" case because this may be a filehandle that was created by
-	 * fh_compose, and that is about to be used in another nfsv4 compound
-	 * operation */
-	error = nfserrno(nfsd_setuser(rqstp, exp));
-	if (error)
-		goto out;

 	error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
 	if (error)
-
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