linux-kernel - [057/111] Btrfs: deny sys

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Date:	Wed, 11 Aug 2010 16:54:38 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	TARUISI Hiroaki <taruishi.hiroak@...fujitsu.com>,
	Chris Mason <chris.mason@...cle.com>,
	Jeff Mahoney <jeffm@...e.com>
Subject: [057/111] Btrfs: deny sys_link across subvolumes.

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

From: TARUISI Hiroaki <taruishi.hiroak@...fujitsu.com>

commit 4a8be425a8fb8fbb5d881eb55fa6634c3463b9c9 upstream.

I rebased Christian Parpart's patch to deny hard link across
subvolumes. Original patch modifies also btrfs_rename, but
I excluded it because we can move across subvolumes now and
it make no problem.
-----------------

Hard link across subvolumes should not allowed in Btrfs.
btrfs_link checks root of 'to' directory is same as root
of 'from' file. If not same, btrfs_link returns -EPERM.

Signed-off-by: TARUISI Hiroaki <taruishi.hiroak@...fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@...cle.com>
Acked-by: Jeff Mahoney <jeffm@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>


---
 fs/btrfs/inode.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4462,6 +4462,10 @@ static int btrfs_link(struct dentry *old
 	if (inode->i_nlink == 0)
 		return -ENOENT;
 
+	/* do not allow sys_link's with other subvols of the same device */
+	if (root->objectid != BTRFS_I(inode)->root->objectid)
+		return -EPERM;
+
 	/*
 	 * 1 item for inode ref
 	 * 2 items for dir items


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