check privileges before setting mount propagation

There's a missing check for CAP_SYS_ADMIN in do_change_type().

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 72bb1062bfe7..b696e3a0d18f 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -886,6 +886,9 @@ static int do_change_type(struct nameidata *nd, int flag)
         int recurse = flag & MS_REC;
         int type = flag & ~MS_REC;
 
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
         if (nd->dentry != nd->mnt->mnt_root)
                 return -EINVAL;