CRED: Pass credentials through dentry_open()

Pass credentials through dentry_open() so that the COW creds patch can have
SELinux's flush_unauthorized_files() pass the appropriate creds back to itself
when it opens its null chardev.

The security_dentry_open() call also now takes a creds pointer, as does the
dentry_open hook in struct security_operations.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/security.c b/security/security.c
index d058f7d..f40a0a0 100644
--- a/security/security.c
+++ b/security/security.c
@@ -606,9 +606,9 @@
 	return security_ops->file_receive(file);
 }
 
-int security_dentry_open(struct file *file)
+int security_dentry_open(struct file *file, const struct cred *cred)
 {
-	return security_ops->dentry_open(file);
+	return security_ops->dentry_open(file, cred);
 }
 
 int security_task_create(unsigned long clone_flags)