linux-kernel - [174/200] Btrfs: should add a permission check for setfacl

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Date:	Thu, 01 Jul 2010 10:44:24 -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,
	Shi Weihua <shiwh@...fujitsu.com>,
	Chris Mason <chris.mason@...cle.com>
Subject: [174/200] Btrfs: should add a permission check for setfacl

2.6.34-stable review patch.  If anyone has any objections, please let me know.

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

From: Shi Weihua <shiwh@...fujitsu.com>

commit 2f26afba46f0ebf155cf9be746496a0304a5b7cf upstream.

On btrfs, do the following
------------------
# su user1
# cd btrfs-part/
# touch aaa
# getfacl aaa
  # file: aaa
  # owner: user1
  # group: user1
  user::rw-
  group::rw-
  other::r--
# su user2
# cd btrfs-part/
# setfacl -m u::rwx aaa
# getfacl aaa
  # file: aaa
  # owner: user1
  # group: user1
  user::rwx           <- successed to setfacl
  group::rw-
  other::r--
------------------
but we should prohibit it that user2 changing user1's acl.
In fact, on ext3 and other fs, a message occurs:
  setfacl: aaa: Operation not permitted

This patch fixed it.

Signed-off-by: Shi Weihua <shiwh@...fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@...cle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 fs/btrfs/acl.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/btrfs/acl.c
+++ b/fs/btrfs/acl.c
@@ -160,6 +160,9 @@ static int btrfs_xattr_acl_set(struct de
 	int ret;
 	struct posix_acl *acl = NULL;
 
+	if (!is_owner_or_cap(dentry->d_inode))
+		return -EPERM;
+
 	if (value) {
 		acl = posix_acl_from_xattr(value, size);
 		if (acl == NULL) {


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