TCPCT part 1a: add request_values parameter for sending SYNACK

Add optional function parameters associated with sending SYNACK.
These parameters are not needed after sending SYNACK, and are not
used for retransmission.  Avoids extending struct tcp_request_sock,
and avoids allocating kernel memory.

Also affects DCCP as it uses common struct request_sock_ops,
but this parameter is currently reserved for future use.

Signed-off-by: William.Allen.Simpson@gmail.com
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/request_sock.h

@@ -27,13 +27,19 @@ struct sk_buff;
 struct dst_entry;
 struct proto;
 
+/* empty to "strongly type" an otherwise void parameter.
+ */
+struct request_values {
+};
+
 struct request_sock_ops {
 	int		family;
 	int		obj_size;
 	struct kmem_cache	*slab;
 	char		*slab_name;
 	int		(*rtx_syn_ack)(struct sock *sk,
-				       struct request_sock *req);
+				       struct request_sock *req,
+				       struct request_values *rvp);
 	void		(*send_ack)(struct sock *sk, struct sk_buff *skb,
 				    struct request_sock *req);
 	void		(*send_reset)(struct sock *sk,

include/net/tcp.h

@@ -440,7 +440,8 @@ extern int			tcp_connect(struct sock *sk);
 
 extern struct sk_buff *		tcp_make_synack(struct sock *sk,
 						struct dst_entry *dst,
-						struct request_sock *req);
+						struct request_sock *req,
+						struct request_values *rvp);
 
 extern int			tcp_disconnect(struct sock *sk, int flags);
 

net/dccp/ipv4.c

@@ -477,7 +477,8 @@ static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
 	return &rt->u.dst;
 }
 
-static int dccp_v4_send_response(struct sock *sk, struct request_sock *req)
+static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
+				 struct request_values *rv_unused)
 {
 	int err = -1;
 	struct sk_buff *skb;
@@ -626,7 +627,7 @@ int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 	dreq->dreq_iss	   = dccp_v4_init_sequence(skb);
 	dreq->dreq_service = service;
 
-	if (dccp_v4_send_response(sk, req))
+	if (dccp_v4_send_response(sk, req, NULL))
 		goto drop_and_free;
 
 	inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);

net/dccp/ipv6.c

@@ -241,7 +241,8 @@ out:
 }
 
 
-static int dccp_v6_send_response(struct sock *sk, struct request_sock *req)
+static int dccp_v6_send_response(struct sock *sk, struct request_sock *req,
+				 struct request_values *rv_unused)
 {
 	struct inet6_request_sock *ireq6 = inet6_rsk(req);
 	struct ipv6_pinfo *np = inet6_sk(sk);
@@ -468,7 +469,7 @@ static int dccp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 	dreq->dreq_iss	   = dccp_v6_init_sequence(skb);
 	dreq->dreq_service = service;
 
-	if (dccp_v6_send_response(sk, req))
+	if (dccp_v6_send_response(sk, req, NULL))
 		goto drop_and_free;
 
 	inet6_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);

net/dccp/minisocks.c

@@ -184,7 +184,7 @@ struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 			 * counter (backoff, monitored by dccp_response_timer).
 			 */
 			req->retrans++;
-			req->rsk_ops->rtx_syn_ack(sk, req);
+			req->rsk_ops->rtx_syn_ack(sk, req, NULL);
 		}
 		/* Network Duplicate, discard packet */
 		return NULL;

net/ipv4/inet_connection_sock.c

@@ -531,7 +531,7 @@ void inet_csk_reqsk_queue_prune(struct sock *parent,
 					       &expire, &resend);
 				if (!expire &&
 				    (!resend ||
-				     !req->rsk_ops->rtx_syn_ack(parent, req) ||
+				     !req->rsk_ops->rtx_syn_ack(parent, req, NULL) ||
 				     inet_rsk(req)->acked)) {
 					unsigned long timeo;
 

net/ipv4/tcp_ipv4.c

@@ -742,8 +742,9 @@ static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
  *	This still operates on a request_sock only, not on a big
  *	socket.
  */
-static int __tcp_v4_send_synack(struct sock *sk, struct request_sock *req,
-				struct dst_entry *dst)
+static int __tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
+				struct request_sock *req,
+				struct request_values *rvp)
 {
 	const struct inet_request_sock *ireq = inet_rsk(req);
 	int err = -1;
@@ -753,7 +754,7 @@ static int __tcp_v4_send_synack(struct sock *sk, struct request_sock *req,
 	if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
 		return -1;
 
-	skb = tcp_make_synack(sk, dst, req);
+	skb = tcp_make_synack(sk, dst, req, rvp);
 
 	if (skb) {
 		struct tcphdr *th = tcp_hdr(skb);
@@ -774,9 +775,10 @@ static int __tcp_v4_send_synack(struct sock *sk, struct request_sock *req,
 	return err;
 }
 
-static int tcp_v4_send_synack(struct sock *sk, struct request_sock *req)
+static int tcp_v4_send_synack(struct sock *sk, struct request_sock *req,
+			      struct request_values *rvp)
 {
-	return __tcp_v4_send_synack(sk, req, NULL);
+	return __tcp_v4_send_synack(sk, NULL, req, rvp);
 }
 
 /*
@@ -1211,13 +1213,13 @@ static struct timewait_sock_ops tcp_timewait_sock_ops = {
 
 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 {
-	struct inet_request_sock *ireq;
 	struct tcp_options_received tmp_opt;
 	struct request_sock *req;
+	struct inet_request_sock *ireq;
+	struct dst_entry *dst = NULL;
 	__be32 saddr = ip_hdr(skb)->saddr;
 	__be32 daddr = ip_hdr(skb)->daddr;
 	__u32 isn = TCP_SKB_CB(skb)->when;
-	struct dst_entry *dst = NULL;
 #ifdef CONFIG_SYN_COOKIES
 	int want_cookie = 0;
 #else
@@ -1337,7 +1339,7 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 	}
 	tcp_rsk(req)->snt_isn = isn;
 
-	if (__tcp_v4_send_synack(sk, req, dst) || want_cookie)
+	if (__tcp_v4_send_synack(sk, dst, req, NULL) || want_cookie)
 		goto drop_and_free;
 
 	inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);

net/ipv4/tcp_minisocks.c

@@ -531,7 +531,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 		 * Enforce "SYN-ACK" according to figure 8, figure 6
 		 * of RFC793, fixed by RFC1122.
 		 */
-		req->rsk_ops->rtx_syn_ack(sk, req);
+		req->rsk_ops->rtx_syn_ack(sk, req, NULL);
 		return NULL;
 	}
 

net/ipv4/tcp_output.c

@@ -2224,7 +2224,8 @@ int tcp_send_synack(struct sock *sk)
 
 /* Prepare a SYN-ACK. */
 struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
-				struct request_sock *req)
+				struct request_sock *req,
+				struct request_values *rvp)
 {
 	struct inet_request_sock *ireq = inet_rsk(req);
 	struct tcp_sock *tp = tcp_sk(sk);

net/ipv6/tcp_ipv6.c

@@ -461,7 +461,8 @@ out:
 }
 
 
-static int tcp_v6_send_synack(struct sock *sk, struct request_sock *req)
+static int tcp_v6_send_synack(struct sock *sk, struct request_sock *req,
+			      struct request_values *rvp)
 {
 	struct inet6_request_sock *treq = inet6_rsk(req);
 	struct ipv6_pinfo *np = inet6_sk(sk);
@@ -499,7 +500,7 @@ static int tcp_v6_send_synack(struct sock *sk, struct request_sock *req)
 	if ((err = xfrm_lookup(sock_net(sk), &dst, &fl, sk, 0)) < 0)
 		goto done;
 
-	skb = tcp_make_synack(sk, dst, req);
+	skb = tcp_make_synack(sk, dst, req, rvp);
 	if (skb) {
 		struct tcphdr *th = tcp_hdr(skb);
 
@@ -1161,13 +1162,13 @@ static struct sock *tcp_v6_hnd_req(struct sock *sk,struct sk_buff *skb)
  */
 static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 {
+	struct tcp_options_received tmp_opt;
+	struct request_sock *req;
 	struct inet6_request_sock *treq;
 	struct ipv6_pinfo *np = inet6_sk(sk);
-	struct tcp_options_received tmp_opt;
 	struct tcp_sock *tp = tcp_sk(sk);
-	struct request_sock *req = NULL;
-	__u32 isn = TCP_SKB_CB(skb)->when;
 	struct dst_entry *dst = __sk_dst_get(sk);
+	__u32 isn = TCP_SKB_CB(skb)->when;
 #ifdef CONFIG_SYN_COOKIES
 	int want_cookie = 0;
 #else
@@ -1239,23 +1240,19 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 
 		isn = tcp_v6_init_sequence(skb);
 	}
-
 	tcp_rsk(req)->snt_isn = isn;
 
 	security_inet_conn_request(sk, skb, req);
 
-	if (tcp_v6_send_synack(sk, req))
-		goto drop;
+	if (tcp_v6_send_synack(sk, req, NULL) || want_cookie)
+		goto drop_and_free;
 
-	if (!want_cookie) {
-		inet6_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
-		return 0;
-	}
+	inet6_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
+	return 0;
 
+drop_and_free:
+	reqsk_free(req);
 drop:
-	if (req)
-		reqsk_free(req);
-
 	return 0; /* don't send reset */
 }