[PATCH 2/2] overlayfs: switch to use inode_only_permissions

[Andy Whitcroft <apw@canonical.com>]

When checking permissions on an overlayfs inode we do not take into
account either device cgroup restrictions nor security permissions.
This allows a user to mount an overlayfs layer over a restricted device
directory and by pass those permissions to open otherwise restricted
files.

Switch over to the newly introduced inode_only_permissions.

Signed-off-by: Andy Whitcroft <apw@canonical.com>
---
 fs/overlayfs/inode.c |    5 +----
 1 files changed, 1 insertions(+), 4 deletions(-)

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index ba1a777..1e3d157 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -114,10 +114,7 @@ int ovl_permission(struct inode *inode, int mask)
 			goto out_dput;
 	}
 
-	if (realinode->i_op->permission)
-		err = realinode->i_op->permission(realinode, mask);
-	else
-		err = generic_permission(realinode, mask);
+	err = inode_only_permission(realinode, mask);
 out_dput:
 	dput(alias);
 	return err;
-- 
1.7.9