Btrfs: add permission checks to the ioctls

Only root can add/remove devices
Only root can defrag subtrees
Only files open for writing can be defragged
Only files open for writing can be the destination for a clone

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 84c3b66564d0..3814238d6eba 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -589,6 +589,9 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
         int ret = 0;
         int len;
 
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
         vol = kmalloc(sizeof(*vol), GFP_KERNEL);
         if (copy_from_user(vol, (void __user *)arg, sizeof(*vol))) {
                 ret = -EFAULT;