1 files changed, 114 insertions, 37 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 7e41e2cbb85e..20aa95e37359 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -130,6 +130,7 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct in6_addr *saddr = NULL, *final_p, final;
+	struct rt6_info *rt;
 	struct flowi fl;
 	struct dst_entry *dst;
 	int addr_type;
@@ -280,6 +281,26 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
 	sk->sk_gso_type = SKB_GSO_TCPV6;
 	__ip6_dst_store(sk, dst, NULL, NULL);
 
+	rt = (struct rt6_info *) dst;
+	if (tcp_death_row.sysctl_tw_recycle &&
+	    !tp->rx_opt.ts_recent_stamp &&
+	    ipv6_addr_equal(&rt->rt6i_dst.addr, &np->daddr)) {
+		struct inet_peer *peer = rt6_get_peer(rt);
+		/*
+		 * VJ's idea. We save last timestamp seen from
+		 * the destination in peer table, when entering state
+		 * TIME-WAIT * and initialize rx_opt.ts_recent from it,
+		 * when trying new connection.
+		 */
+		if (peer) {
+			inet_peer_refcheck(peer);
+			if ((u32)get_seconds() - peer->tcp_ts_stamp <= TCP_PAWS_MSL) {
+				tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
+				tp->rx_opt.ts_recent = peer->tcp_ts;
+			}
+		}
+	}
+
 	icsk->icsk_ext_hdr_len = 0;
 	if (np->opt)
 		icsk->icsk_ext_hdr_len = (np->opt->opt_flen +
@@ -906,12 +927,6 @@ static const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
 };
 #endif
 
-static struct timewait_sock_ops tcp6_timewait_sock_ops = {
-	.twsk_obj_size	= sizeof(struct tcp6_timewait_sock),
-	.twsk_unique	= tcp_twsk_unique,
-	.twsk_destructor= tcp_twsk_destructor,
-};
-
 static void __tcp_v6_send_check(struct sk_buff *skb,
 				struct in6_addr *saddr, struct in6_addr *daddr)
 {
@@ -1176,6 +1191,7 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
 	__u32 isn = TCP_SKB_CB(skb)->when;
+	struct dst_entry *dst = NULL;
 #ifdef CONFIG_SYN_COOKIES
 	int want_cookie = 0;
 #else
@@ -1273,6 +1289,8 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 		TCP_ECN_create_request(req, tcp_hdr(skb));
 
 	if (!isn) {
+		struct inet_peer *peer = NULL;
+
 		if (ipv6_opt_accepted(sk, skb) ||
 		    np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo ||
 		    np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim) {
@@ -1285,13 +1303,57 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 		if (!sk->sk_bound_dev_if &&
 		    ipv6_addr_type(&treq->rmt_addr) & IPV6_ADDR_LINKLOCAL)
 			treq->iif = inet6_iif(skb);
-		if (!want_cookie) {
-			isn = tcp_v6_init_sequence(skb);
-		} else {
+
+		if (want_cookie) {
 			isn = cookie_v6_init_sequence(sk, skb, &req->mss);
 			req->cookie_ts = tmp_opt.tstamp_ok;
+			goto have_isn;
 		}
+
+		/* VJ's idea. We save last timestamp seen
+		 * from the destination in peer table, when entering
+		 * state TIME-WAIT, and check against it before
+		 * accepting new connection request.
+		 *
+		 * If "isn" is not zero, this request hit alive
+		 * timewait bucket, so that all the necessary checks
+		 * are made in the function processing timewait state.
+		 */
+		if (tmp_opt.saw_tstamp &&
+		    tcp_death_row.sysctl_tw_recycle &&
+		    (dst = inet6_csk_route_req(sk, req)) != NULL &&
+		    (peer = rt6_get_peer((struct rt6_info *)dst)) != NULL &&
+		    ipv6_addr_equal((struct in6_addr *)peer->daddr.a6,
+				    &treq->rmt_addr)) {
+			inet_peer_refcheck(peer);
+			if ((u32)get_seconds() - peer->tcp_ts_stamp < TCP_PAWS_MSL &&
+			    (s32)(peer->tcp_ts - req->ts_recent) >
+							TCP_PAWS_WINDOW) {
+				NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
+				goto drop_and_release;
+			}
+		}
+		/* Kill the following clause, if you dislike this way. */
+		else if (!sysctl_tcp_syncookies &&
+			 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
+			  (sysctl_max_syn_backlog >> 2)) &&
+			 (!peer || !peer->tcp_ts_stamp) &&
+			 (!dst || !dst_metric(dst, RTAX_RTT))) {
+			/* Without syncookies last quarter of
+			 * backlog is filled with destinations,
+			 * proven to be alive.
+			 * It means that we continue to communicate
+			 * to destinations, already remembered
+			 * to the moment of synflood.
+			 */
+			LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open request from %pI6/%u\n",
+				       &treq->rmt_addr, ntohs(tcp_hdr(skb)->source));
+			goto drop_and_release;
+		}
+
+		isn = tcp_v6_init_sequence(skb);
 	}
+have_isn:
 	tcp_rsk(req)->snt_isn = isn;
 
 	security_inet_conn_request(sk, skb, req);
@@ -1304,6 +1366,8 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 	inet6_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
 	return 0;
 
+drop_and_release:
+	dst_release(dst);
 drop_and_free:
 	reqsk_free(req);
 drop:
@@ -1382,28 +1446,9 @@ static struct sock * tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
 	if (sk_acceptq_is_full(sk))
 		goto out_overflow;
 
-	if (dst == NULL) {
-		struct in6_addr *final_p, final;
-		struct flowi fl;
-
-		memset(&fl, 0, sizeof(fl));
-		fl.proto = IPPROTO_TCP;
-		ipv6_addr_copy(&fl.fl6_dst, &treq->rmt_addr);
-		final_p = fl6_update_dst(&fl, opt, &final);
-		ipv6_addr_copy(&fl.fl6_src, &treq->loc_addr);
-		fl.oif = sk->sk_bound_dev_if;
-		fl.mark = sk->sk_mark;
-		fl.fl_ip_dport = inet_rsk(req)->rmt_port;
-		fl.fl_ip_sport = inet_rsk(req)->loc_port;
-		security_req_classify_flow(req, &fl);
-
-		if (ip6_dst_lookup(sk, &dst, &fl))
-			goto out;
-
-		if (final_p)
-			ipv6_addr_copy(&fl.fl6_dst, final_p);
-
-		if ((xfrm_lookup(sock_net(sk), &dst, &fl, sk, 0)) < 0)
+	if (!dst) {
+		dst = inet6_csk_route_req(sk, req);
+		if (!dst)
 			goto out;
 	}
 
@@ -1476,7 +1521,7 @@ static struct sock * tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
 
 	tcp_mtup_init(newsk);
 	tcp_sync_mss(newsk, dst_mtu(dst));
-	newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
+	newtp->advmss = dst_metric_advmss(dst);
 	tcp_initialize_rcv_mss(newsk);
 
 	newinet->inet_daddr = newinet->inet_saddr = LOOPBACK4_IPV6;
@@ -1818,19 +1863,51 @@ do_time_wait:
 	goto discard_it;
 }
 
-static int tcp_v6_remember_stamp(struct sock *sk)
+static struct inet_peer *tcp_v6_get_peer(struct sock *sk, bool *release_it)
 {
-	/* Alas, not yet... */
-	return 0;
+	struct rt6_info *rt = (struct rt6_info *) __sk_dst_get(sk);
+	struct ipv6_pinfo *np = inet6_sk(sk);
+	struct inet_peer *peer;
+
+	if (!rt ||
+	    !ipv6_addr_equal(&np->daddr, &rt->rt6i_dst.addr)) {
+		peer = inet_getpeer_v6(&np->daddr, 1);
+		*release_it = true;
+	} else {
+		if (!rt->rt6i_peer)
+			rt6_bind_peer(rt, 1);
+		peer = rt->rt6i_peer;
+		*release_it = false;
+	}
+
+	return peer;
 }
 
+static void *tcp_v6_tw_get_peer(struct sock *sk)
+{
+	struct inet6_timewait_sock *tw6 = inet6_twsk(sk);
+	struct inet_timewait_sock *tw = inet_twsk(sk);
+
+	if (tw->tw_family == AF_INET)
+		return tcp_v4_tw_get_peer(sk);
+
+	return inet_getpeer_v6(&tw6->tw_v6_daddr, 1);
+}
+
+static struct timewait_sock_ops tcp6_timewait_sock_ops = {
+	.twsk_obj_size	= sizeof(struct tcp6_timewait_sock),
+	.twsk_unique	= tcp_twsk_unique,
+	.twsk_destructor= tcp_twsk_destructor,
+	.twsk_getpeer	= tcp_v6_tw_get_peer,
+};
+
 static const struct inet_connection_sock_af_ops ipv6_specific = {
 	.queue_xmit	   = inet6_csk_xmit,
 	.send_check	   = tcp_v6_send_check,
 	.rebuild_header	   = inet6_sk_rebuild_header,
 	.conn_request	   = tcp_v6_conn_request,
 	.syn_recv_sock	   = tcp_v6_syn_recv_sock,
-	.remember_stamp	   = tcp_v6_remember_stamp,
+	.get_peer	   = tcp_v6_get_peer,
 	.net_header_len	   = sizeof(struct ipv6hdr),
 	.setsockopt	   = ipv6_setsockopt,
 	.getsockopt	   = ipv6_getsockopt,
@@ -1862,7 +1939,7 @@ static const struct inet_connection_sock_af_ops ipv6_mapped = {
 	.rebuild_header	   = inet_sk_rebuild_header,
 	.conn_request	   = tcp_v6_conn_request,
 	.syn_recv_sock	   = tcp_v6_syn_recv_sock,
-	.remember_stamp	   = tcp_v4_remember_stamp,
+	.get_peer	   = tcp_v4_get_peer,
 	.net_header_len	   = sizeof(struct iphdr),
 	.setsockopt	   = ipv6_setsockopt,
 	.getsockopt	   = ipv6_getsockopt,