BTRFS_IOC_TRANS_START should be privilegued

As mentioned in the comment next to it btrfs_ioctl_trans_start can
do bad damage to filesystems and thus should be limited to privilegued
users.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index da8de6cfdb5a..6fb455802759 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -706,6 +706,9 @@ long btrfs_ioctl_trans_start(struct file *file)
         struct btrfs_trans_handle *trans;
         int ret = 0;
 
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
         mutex_lock(&root->fs_info->fs_mutex);
         if (file->private_data) {
                 ret = -EINPROGRESS;