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>

diff --git a/fs/namespace.c b/fs/namespace.c
index 72bb1062bfe77886394a79c0822ec141aad55045..b696e3a0d18fcf2d4bb017dcaa36dacb39c565e6 100644 (file)
--- 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;