Patchwork [3.5.y.z,extended,stable] Patch "nfsd: avoid permission checks on EXCLUSIVE_CREATE" has been added to staging queue

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Submitter Herton Ronaldo Krzesinski
Date Jan. 8, 2013, 8:57 p.m.
Message ID <1357678624-19739-1-git-send-email-herton.krzesinski@canonical.com>
Download mbox | patch
Permalink /patch/210507/
State New
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Herton Ronaldo Krzesinski - Jan. 8, 2013, 8:57 p.m.
This is a note to let you know that I have just added a patch titled

    nfsd: avoid permission checks on EXCLUSIVE_CREATE

to the linux-3.5.y-queue branch of the 3.5.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-3.5.y-queue

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

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

From 6dd47d311746e63882f12bece646ead7eccf90ea Mon Sep 17 00:00:00 2001
From: Neil Brown <neilb@suse.de>
Date: Fri, 7 Dec 2012 15:40:55 -0500
Subject: [PATCH 08/27] nfsd: avoid permission checks on EXCLUSIVE_CREATE
 replay

commit 7007c90fb9fef593b4aeaeee57e6a6754276c97c upstream.

With NFSv4, if we create a file then open it we explicit avoid checking
the permissions on the file during the open because the fact that we
created it ensures we should be allow to open it (the create and the
open should appear to be a single operation).

However if the reply to an EXCLUSIVE create gets lots and the client
resends the create, the current code will perform the permission check -
because it doesn't realise that it did the open already..

This patch should fix this.

Note that I haven't actually seen this cause a problem.  I was just
looking at the code trying to figure out a different EXCLUSIVE open
related issue, and this looked wrong.

(Fix confirmed with pynfs 4.0 test OPEN4--bfields)

Signed-off-by: NeilBrown <neilb@suse.de>
[bfields: use OWNER_OVERRIDE and update for 4.1]
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
---
 fs/nfsd/nfs4proc.c |    8 +++++---
 fs/nfsd/vfs.c      |   10 ++++++++--
 2 files changed, 13 insertions(+), 5 deletions(-)

--
1.7.9.5

Patch

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 987e719..dd0308d 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -194,6 +194,7 @@  static __be32
 do_open_lookup(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_open *open)
 {
 	struct svc_fh *resfh;
+	int accmode;
 	__be32 status;

 	resfh = kmalloc(sizeof(struct svc_fh), GFP_KERNEL);
@@ -253,9 +254,10 @@  do_open_lookup(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_o
 	/* set reply cache */
 	fh_copy_shallow(&open->op_openowner->oo_owner.so_replay.rp_openfh,
 			&resfh->fh_handle);
-	if (!open->op_created)
-		status = do_open_permission(rqstp, resfh, open,
-					    NFSD_MAY_NOP);
+	accmode = NFSD_MAY_NOP;
+	if (open->op_created)
+		accmode |= NFSD_MAY_OWNER_OVERRIDE;
+	status = do_open_permission(rqstp, resfh, open, accmode);
 	set_change_info(&open->op_cinfo, current_fh);
 	fh_dup2(current_fh, resfh);
 out:
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index c8bd9c3..0191ede 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1477,13 +1477,19 @@  do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		case NFS3_CREATE_EXCLUSIVE:
 			if (   dchild->d_inode->i_mtime.tv_sec == v_mtime
 			    && dchild->d_inode->i_atime.tv_sec == v_atime
-			    && dchild->d_inode->i_size  == 0 )
+			    && dchild->d_inode->i_size  == 0 ) {
+				if (created)
+					*created = 1;
 				break;
+			}
 		case NFS4_CREATE_EXCLUSIVE4_1:
 			if (   dchild->d_inode->i_mtime.tv_sec == v_mtime
 			    && dchild->d_inode->i_atime.tv_sec == v_atime
-			    && dchild->d_inode->i_size  == 0 )
+			    && dchild->d_inode->i_size  == 0 ) {
+				if (created)
+					*created = 1;
 				goto set_attr;
+			}
 			 /* fallthru */
 		case NFS3_CREATE_GUARDED:
 			err = nfserr_exist;