[ 3.8.y.z extended stable ] Patch "nfsd4: don't allow owner override on 4.1 CLAIM_FH opens" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    nfsd4: don't allow owner override on 4.1 CLAIM_FH opens

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.4.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 46c966eadc4713cd455114a2929fcab0bf5bf265 Mon Sep 17 00:00:00 2001
From: "J. Bruce Fields" <bfields at redhat.com>
Date: Fri, 3 May 2013 16:09:09 -0400
Subject: nfsd4: don't allow owner override on 4.1 CLAIM_FH opens

commit 9f415eb25574db4b73a9a712a4438e41dc284922 upstream.

The Linux client is using CLAIM_FH to implement regular opens, not just
recovery cases, so it depends on the server to check permissions
correctly.

Therefore the owner override, which may make sense in the delegation
recovery case, isn't right in the CLAIM_FH case.

Symptoms: on a client with 49f9a0fafd844c32f2abada047c0b9a5ba0d6255
"NFSv4.1: Enable open-by-filehandle", Bryan noticed this:

	touch test.txt
	chmod 000 test.txt
	echo test > test.txt

succeeding.

Reported-by: Bryan Schumaker <bjschuma at netapp.com>
Signed-off-by: J. Bruce Fields <bfields at redhat.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/nfsd/nfs4proc.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index ec668e1..de60696 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -271,6 +271,7 @@ static __be32
 do_open_fhandle(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_open *open)
 {
 	__be32 status;
+	int accmode = 0;

 	/* We don't know the target directory, and therefore can not
 	* set the change info
@@ -284,9 +285,19 @@ do_open_fhandle(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_

 	open->op_truncate = (open->op_iattr.ia_valid & ATTR_SIZE) &&
 		(open->op_iattr.ia_size == 0);
+	/*
+	 * In the delegation case, the client is telling us about an
+	 * open that it *already* performed locally, some time ago.  We
+	 * should let it succeed now if possible.
+	 *
+	 * In the case of a CLAIM_FH open, on the other hand, the client
+	 * may be counting on us to enforce permissions (the Linux 4.1
+	 * client uses this for normal opens, for example).
+	 */
+	if (open->op_claim_type == NFS4_OPEN_CLAIM_DELEG_CUR_FH)
+		accmode = NFSD_MAY_OWNER_OVERRIDE;

-	status = do_open_permission(rqstp, current_fh, open,
-				    NFSD_MAY_OWNER_OVERRIDE);
+	status = do_open_permission(rqstp, current_fh, open, accmode);

 	return status;
 }
--
1.8.1.2