From: Ben Hutchings <ben@decadent.org.uk>
Date: Wed, 29 Dec 2010 14:55:03 +0000 (+0000)
Subject: btrfs: Require CAP_SYS_ADMIN for filesystem rebalance
X-Git-Tag: v2.6.35.14~195
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c5e74595507c13d213d716475d9c9fa061cd263c;p=thirdparty%2Fkernel%2Fstable.git

btrfs: Require CAP_SYS_ADMIN for filesystem rebalance

commit 6f88a4403def422bd8e276ddf6863d6ac71435d2 upstream.

Filesystem rebalancing (BTRFS_IOC_BALANCE) affects the entire
filesystem and may run uninterruptibly for a long time.  This does not
seem to be something that an unprivileged user should be able to do.

Reported-by: Aron Xu <happyaron.xu@gmail.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index d6e3af8be95b9..dc0dedfa8e0cf 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -22,6 +22,7 @@
 #include <linux/blkdev.h>
 #include <linux/random.h>
 #include <linux/iocontext.h>
+#include <linux/capability.h>
 #include <asm/div64.h>
 #include "compat.h"
 #include "ctree.h"
@@ -1909,6 +1910,9 @@ int btrfs_balance(struct btrfs_root *dev_root)
 	if (dev_root->fs_info->sb->s_flags & MS_RDONLY)
 		return -EROFS;
 
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
 	mutex_lock(&dev_root->fs_info->volume_mutex);
 	dev_root = dev_root->fs_info->dev_root;