1 files changed, 76 insertions, 25 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 5f73a1808e36..c2ebbe1c5a47 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 +
@@ -1170,6 +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
@@ -1267,6 +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) {
@@ -1279,13 +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);
@@ -1298,6 +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:
@@ -1376,28 +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;
         }