NetLabel: honor the audit_enabled flag

The audit_enabled flag is used to signal when syscall auditing is to be
performed.  While NetLabel uses a Netlink interface instead of syscalls, it is
reasonable to consider the NetLabel Netlink interface as a form of syscall so
pay attention to the audit_enabled flag when generating audit messages in
NetLabel.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
index 07283e1..5bc3718 100644
--- a/net/netlabel/netlabel_unlabeled.c
+++ b/net/netlabel/netlabel_unlabeled.c
@@ -35,6 +35,7 @@
 #include <linux/socket.h>
 #include <linux/string.h>
 #include <linux/skbuff.h>
+#include <linux/audit.h>
 #include <net/sock.h>
 #include <net/netlink.h>
 #include <net/genetlink.h>
@@ -92,8 +93,11 @@
 
 	audit_buf = netlbl_audit_start_common(AUDIT_MAC_UNLBL_ALLOW,
 					      audit_info);
-	audit_log_format(audit_buf, " unlbl_accept=%u old=%u", value, old_val);
-	audit_log_end(audit_buf);
+	if (audit_buf != NULL) {
+		audit_log_format(audit_buf,
+				 " unlbl_accept=%u old=%u", value, old_val);
+		audit_log_end(audit_buf);
+	}
 }
 
 /*