btrfs: Require CAP_SYS_ADMIN for filesystem rebalance
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>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index e8be478..f2d2f4c 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"
@@ -2024,6 +2025,9 @@
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;