inet_diag: allow protocols to provide additional data

Extend inet_diag_handler to allow individual protocols to report
additional data on INET_DIAG_INFO through idiag_get_aux. The size
can be dynamic and is computed by idiag_get_aux_size.

Signed-off-by: Ivan Delalande <colona@arista.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/inet_diag.h b/include/linux/inet_diag.h
index 65da430..ee251c5 100644
--- a/include/linux/inet_diag.h
+++ b/include/linux/inet_diag.h
@@ -25,6 +25,13 @@ struct inet_diag_handler {
 					  struct inet_diag_msg *r,
 					  void *info);
 
+	int		(*idiag_get_aux)(struct sock *sk,
+					 bool net_admin,
+					 struct sk_buff *skb);
+
+	size_t		(*idiag_get_aux_size)(struct sock *sk,
+					      bool net_admin);
+
 	int		(*destroy)(struct sk_buff *in_skb,
 				   const struct inet_diag_req_v2 *req);