tcp: pass fl6 to inet6_csk_route_req()

This commit changes inet_csk_route_req() so that it uses a pointer to
a struct flowi6, rather than allocating its own on the stack. This
brings its behavior in line with its IPv4 cousin,
inet_csk_route_req(), and allows a follow-on patch to fix a dst leak.
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet6_connection_sock.h

@@ -26,6 +26,7 @@ extern int inet6_csk_bind_conflict(const struct sock *sk,
 				   const struct inet_bind_bucket *tb, bool relax);
 
 extern struct dst_entry* inet6_csk_route_req(struct sock *sk,
+					     struct flowi6 *fl6,
 					     const struct request_sock *req);
 
 extern struct request_sock *inet6_csk_search_req(const struct sock *sk,

net/ipv6/inet6_connection_sock.c

@@ -55,26 +55,26 @@ int inet6_csk_bind_conflict(const struct sock *sk,
 EXPORT_SYMBOL_GPL(inet6_csk_bind_conflict);
 
 struct dst_entry *inet6_csk_route_req(struct sock *sk,
+				      struct flowi6 *fl6,
 				      const struct request_sock *req)
 {
 	struct inet6_request_sock *treq = inet6_rsk(req);
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	struct in6_addr *final_p, final;
 	struct dst_entry *dst;
-	struct flowi6 fl6;
-
-	memset(&fl6, 0, sizeof(fl6));
-	fl6.flowi6_proto = IPPROTO_TCP;
-	fl6.daddr = treq->rmt_addr;
-	final_p = fl6_update_dst(&fl6, np->opt, &final);
-	fl6.saddr = treq->loc_addr;
-	fl6.flowi6_oif = treq->iif;
-	fl6.flowi6_mark = sk->sk_mark;
-	fl6.fl6_dport = inet_rsk(req)->rmt_port;
-	fl6.fl6_sport = inet_rsk(req)->loc_port;
-	security_req_classify_flow(req, flowi6_to_flowi(&fl6));
 
-	dst = ip6_dst_lookup_flow(sk, &fl6, final_p, false);
+	memset(fl6, 0, sizeof(*fl6));
+	fl6->flowi6_proto = IPPROTO_TCP;
+	fl6->daddr = treq->rmt_addr;
+	final_p = fl6_update_dst(fl6, np->opt, &final);
+	fl6->saddr = treq->loc_addr;
+	fl6->flowi6_oif = treq->iif;
+	fl6->flowi6_mark = sk->sk_mark;
+	fl6->fl6_dport = inet_rsk(req)->rmt_port;
+	fl6->fl6_sport = inet_rsk(req)->loc_port;
+	security_req_classify_flow(req, flowi6_to_flowi(fl6));
+
+	dst = ip6_dst_lookup_flow(sk, fl6, final_p, false);
 	if (IS_ERR(dst))
 		return NULL;
 

net/ipv6/tcp_ipv6.c

@@ -477,7 +477,8 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 }
 
 
-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,
 			      u16 queue_mapping)
 {
@@ -1058,6 +1059,7 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 	struct tcp_sock *tp = tcp_sk(sk);
 	__u32 isn = TCP_SKB_CB(skb)->when;
 	struct dst_entry *dst = NULL;
+	struct flowi6 fl6;
 	bool want_cookie = false;
 
 	if (skb->protocol == htons(ETH_P_IP))
@@ -1177,7 +1179,7 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 		 */
 		if (tmp_opt.saw_tstamp &&
 		    tcp_death_row.sysctl_tw_recycle &&
-		    (dst = inet6_csk_route_req(sk, req)) != NULL &&
+		    (dst = inet6_csk_route_req(sk, &fl6, req)) != NULL &&
 		    (peer = rt6_get_peer((struct rt6_info *)dst)) != NULL &&
 		    ipv6_addr_equal((struct in6_addr *)peer->daddr.addr.a6,
 				    &treq->rmt_addr)) {
@@ -1247,6 +1249,7 @@ static struct sock * tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
 #ifdef CONFIG_TCP_MD5SIG
 	struct tcp_md5sig_key *key;
 #endif
+	struct flowi6 fl6;
 
 	if (skb->protocol == htons(ETH_P_IP)) {
 		/*
@@ -1309,7 +1312,7 @@ static struct sock * tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
 		goto out_overflow;
 
 	if (!dst) {
-		dst = inet6_csk_route_req(sk, req);
+		dst = inet6_csk_route_req(sk, &fl6, req);
 		if (!dst)
 			goto out;
 	}