1 files changed, 37 insertions, 6 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index b42fa41cfceb..063898cae3e5 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -343,11 +343,20 @@ failure:
 static void tcp_v6_mtu_reduced(struct sock *sk)
 {
 	struct dst_entry *dst;
+	u32 mtu;
 
 	if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE))
 		return;
 
-	dst = inet6_csk_update_pmtu(sk, tcp_sk(sk)->mtu_info);
+	mtu = READ_ONCE(tcp_sk(sk)->mtu_info);
+
+	/* Drop requests trying to increase our current mss.
+	 * Check done in __ip6_rt_update_pmtu() is too late.
+	 */
+	if (tcp_mtu_to_mss(sk, mtu) >= tcp_sk(sk)->mss_cache)
+		return;
+
+	dst = inet6_csk_update_pmtu(sk, mtu);
 	if (!dst)
 		return;
 
@@ -428,6 +437,8 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	}
 
 	if (type == ICMPV6_PKT_TOOBIG) {
+		u32 mtu = ntohl(info);
+
 		/* We are not interested in TCP_LISTEN and open_requests
 		 * (SYN-ACKs send out by Linux are always <576bytes so
 		 * they should go through unfragmented).
@@ -438,7 +449,11 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 		if (!ip6_sk_accept_pmtu(sk))
 			goto out;
 
-		tp->mtu_info = ntohl(info);
+		if (mtu < IPV6_MIN_MTU)
+			goto out;
+
+		WRITE_ONCE(tp->mtu_info, mtu);
+
 		if (!sock_owned_by_user(sk))
 			tcp_v6_mtu_reduced(sk);
 		else if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED,
@@ -513,8 +528,8 @@ static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
 		opt = ireq->ipv6_opt;
 		if (!opt)
 			opt = rcu_dereference(np->opt);
-		err = ip6_xmit(sk, skb, fl6, sk->sk_mark, opt, np->tclass,
-			       sk->sk_priority);
+		err = ip6_xmit(sk, skb, fl6, skb->mark ? : sk->sk_mark, opt,
+			       np->tclass, sk->sk_priority);
 		rcu_read_unlock();
 		err = net_xmit_eval(err);
 	}
@@ -785,7 +800,7 @@ struct request_sock_ops tcp6_request_sock_ops __read_mostly = {
 	.syn_ack_timeout =	tcp_syn_ack_timeout,
 };
 
-static const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
+const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
 	.mss_clamp	=	IPV6_MIN_MTU - sizeof(struct tcphdr) -
 				sizeof(struct ipv6hdr),
 #ifdef CONFIG_TCP_MD5SIG
@@ -1093,6 +1108,11 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 	if (!ipv6_unicast_destination(skb))
 		goto drop;
 
+	if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
+		__IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
+		return 0;
+	}
+
 	return tcp_conn_request(&tcp6_request_sock_ops,
 				&tcp_request_sock_ipv6_ops, sk, skb);
 
@@ -1122,6 +1142,7 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
 	const struct ipv6_pinfo *np = tcp_inet6_sk(sk);
 	struct ipv6_txoptions *opt;
 	struct inet_sock *newinet;
+	bool found_dup_sk = false;
 	struct tcp_sock *newtp;
 	struct sock *newsk;
 #ifdef CONFIG_TCP_MD5SIG
@@ -1288,7 +1309,8 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
 		tcp_done(newsk);
 		goto out;
 	}
-	*own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash));
+	*own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash),
+				       &found_dup_sk);
 	if (*own_req) {
 		tcp_move_syn(newtp, req);
 
@@ -1303,6 +1325,15 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
 				skb_set_owner_r(newnp->pktoptions, newsk);
 			}
 		}
+	} else {
+		if (!req_unhash && found_dup_sk) {
+			/* This code path should only be executed in the
+			 * syncookie case only
+			 */
+			bh_unlock_sock(newsk);
+			sock_put(newsk);
+			newsk = NULL;
+		}
 	}
 
 	return newsk;