netns: Add a limit on the number of net namespaces

Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 335cc5d..205f1a0 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -71,6 +71,7 @@
 	UCOUNT_ENTRY("max_pid_namespaces"),
 	UCOUNT_ENTRY("max_uts_namespaces"),
 	UCOUNT_ENTRY("max_ipc_namespaces"),
+	UCOUNT_ENTRY("max_net_namespaces"),
 	UCOUNT_ENTRY("max_cgroup_namespaces"),
 	{ }
 };