1 files changed, 228 insertions, 67 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 5def3c48870e..88b987ca9ebb 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -77,7 +77,7 @@
 #include <asm/unaligned.h>
 #include <linux/errqueue.h>
 #include <trace/events/tcp.h>
-#include <linux/static_key.h>
+#include <linux/jump_label_ratelimit.h>
 #include <net/busy_poll.h>
 
 int sysctl_tcp_max_orphans __read_mostly = NR_FILE;
@@ -113,22 +113,28 @@ int sysctl_tcp_max_orphans __read_mostly = NR_FILE;
 #define REXMIT_NEW	2 /* FRTO-style transmit of unsent/new packets */
 
 #if IS_ENABLED(CONFIG_TLS_DEVICE)
-static DEFINE_STATIC_KEY_FALSE(clean_acked_data_enabled);
+static DEFINE_STATIC_KEY_DEFERRED_FALSE(clean_acked_data_enabled, HZ);
 
 void clean_acked_data_enable(struct inet_connection_sock *icsk,
 			     void (*cad)(struct sock *sk, u32 ack_seq))
 {
 	icsk->icsk_clean_acked = cad;
-	static_branch_inc(&clean_acked_data_enabled);
+	static_branch_deferred_inc(&clean_acked_data_enabled);
 }
 EXPORT_SYMBOL_GPL(clean_acked_data_enable);
 
 void clean_acked_data_disable(struct inet_connection_sock *icsk)
 {
-	static_branch_dec(&clean_acked_data_enabled);
+	static_branch_slow_dec_deferred(&clean_acked_data_enabled);
 	icsk->icsk_clean_acked = NULL;
 }
 EXPORT_SYMBOL_GPL(clean_acked_data_disable);
+
+void clean_acked_data_flush(void)
+{
+	static_key_deferred_flush(&clean_acked_data_enabled);
+}
+EXPORT_SYMBOL_GPL(clean_acked_data_flush);
 #endif
 
 static void tcp_gro_dev_warn(struct sock *sk, const struct sk_buff *skb,
@@ -260,7 +266,7 @@ static void tcp_ecn_accept_cwr(struct sock *sk, const struct sk_buff *skb)
 
 static void tcp_ecn_withdraw_cwr(struct tcp_sock *tp)
 {
-	tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
+	tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR;
 }
 
 static void __tcp_ecn_check_ce(struct sock *sk, const struct sk_buff *skb)
@@ -353,7 +359,8 @@ static void tcp_sndbuf_expand(struct sock *sk)
 	sndmem *= nr_segs * per_mss;
 
 	if (sk->sk_sndbuf < sndmem)
-		sk->sk_sndbuf = min(sndmem, sock_net(sk)->ipv4.sysctl_tcp_wmem[2]);
+		WRITE_ONCE(sk->sk_sndbuf,
+			   min(sndmem, sock_net(sk)->ipv4.sysctl_tcp_wmem[2]));
 }
 
 /* 2. Tuning advertised window (window_clamp, rcv_ssthresh)
@@ -402,11 +409,12 @@ static int __tcp_grow_window(const struct sock *sk, const struct sk_buff *skb)
 static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
+	int room;
+
+	room = min_t(int, tp->window_clamp, tcp_space(sk)) - tp->rcv_ssthresh;
 
 	/* Check #1 */
-	if (tp->rcv_ssthresh < tp->window_clamp &&
-	    (int)tp->rcv_ssthresh < tcp_space(sk) &&
-	    !tcp_under_memory_pressure(sk)) {
+	if (room > 0 && !tcp_under_memory_pressure(sk)) {
 		int incr;
 
 		/* Check #2. Increase window, if skb with such overhead
@@ -419,8 +427,7 @@ static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb)
 
 		if (incr) {
 			incr = max_t(int, incr, 2 * skb->len);
-			tp->rcv_ssthresh = min(tp->rcv_ssthresh + incr,
-					       tp->window_clamp);
+			tp->rcv_ssthresh += min(room, incr);
 			inet_csk(sk)->icsk_ack.quick |= 1;
 		}
 	}
@@ -477,8 +484,9 @@ static void tcp_clamp_window(struct sock *sk)
 	    !(sk->sk_userlocks & SOCK_RCVBUF_LOCK) &&
 	    !tcp_under_memory_pressure(sk) &&
 	    sk_memory_allocated(sk) < sk_prot_mem_limits(sk, 0)) {
-		sk->sk_rcvbuf = min(atomic_read(&sk->sk_rmem_alloc),
-				    net->ipv4.sysctl_tcp_rmem[2]);
+		WRITE_ONCE(sk->sk_rcvbuf,
+			   min(atomic_read(&sk->sk_rmem_alloc),
+			       net->ipv4.sysctl_tcp_rmem[2]));
 	}
 	if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf)
 		tp->rcv_ssthresh = min(tp->window_clamp, 2U * tp->advmss);
@@ -642,7 +650,7 @@ void tcp_rcv_space_adjust(struct sock *sk)
 		rcvbuf = min_t(u64, rcvwin * rcvmem,
 			       sock_net(sk)->ipv4.sysctl_tcp_rmem[2]);
 		if (rcvbuf > sk->sk_rcvbuf) {
-			sk->sk_rcvbuf = rcvbuf;
+			WRITE_ONCE(sk->sk_rcvbuf, rcvbuf);
 
 			/* Make the window clamp follow along.  */
 			tp->window_clamp = tcp_win_from_space(sk, rcvbuf);
@@ -772,6 +780,8 @@ static void tcp_rtt_estimator(struct sock *sk, long mrtt_us)
 				tp->rttvar_us -= (tp->rttvar_us - tp->mdev_max_us) >> 2;
 			tp->rtt_seq = tp->snd_nxt;
 			tp->mdev_max_us = tcp_rto_min_us(sk);
+
+			tcp_bpf_rtt(sk);
 		}
 	} else {
 		/* no previous measure. */
@@ -780,6 +790,8 @@ static void tcp_rtt_estimator(struct sock *sk, long mrtt_us)
 		tp->rttvar_us = max(tp->mdev_us, tcp_rto_min_us(sk));
 		tp->mdev_max_us = tp->rttvar_us;
 		tp->rtt_seq = tp->snd_nxt;
+
+		tcp_bpf_rtt(sk);
 	}
 	tp->srtt_us = max(1U, srtt);
 }
@@ -1296,7 +1308,7 @@ static bool tcp_shifted_skb(struct sock *sk, struct sk_buff *prev,
 	TCP_SKB_CB(skb)->seq += shifted;
 
 	tcp_skb_pcount_add(prev, pcount);
-	BUG_ON(tcp_skb_pcount(skb) < pcount);
+	WARN_ON_ONCE(tcp_skb_pcount(skb) < pcount);
 	tcp_skb_pcount_add(skb, -pcount);
 
 	/* When we're adding to gso_segs == 1, gso_size will be zero,
@@ -1362,6 +1374,21 @@ static int skb_can_shift(const struct sk_buff *skb)
 	return !skb_headlen(skb) && skb_is_nonlinear(skb);
 }
 
+int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from,
+		  int pcount, int shiftlen)
+{
+	/* TCP min gso_size is 8 bytes (TCP_MIN_GSO_SIZE)
+	 * Since TCP_SKB_CB(skb)->tcp_gso_segs is 16 bits, we need
+	 * to make sure not storing more than 65535 * 8 bytes per skb,
+	 * even if current MSS is bigger.
+	 */
+	if (unlikely(to->len + shiftlen >= 65535 * TCP_MIN_GSO_SIZE))
+		return 0;
+	if (unlikely(tcp_skb_pcount(to) + pcount > 65535))
+		return 0;
+	return skb_shift(to, from, shiftlen);
+}
+
 /* Try collapsing SACK blocks spanning across multiple skbs to a single
  * skb.
  */
@@ -1467,7 +1494,7 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
 	if (!after(TCP_SKB_CB(skb)->seq + len, tp->snd_una))
 		goto fallback;
 
-	if (!skb_shift(prev, skb, len))
+	if (!tcp_skb_shift(prev, skb, pcount, len))
 		goto fallback;
 	if (!tcp_shifted_skb(sk, prev, skb, state, pcount, len, mss, dup_sack))
 		goto out;
@@ -1485,11 +1512,10 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
 		goto out;
 
 	len = skb->len;
-	if (skb_shift(prev, skb, len)) {
-		pcount += tcp_skb_pcount(skb);
-		tcp_shifted_skb(sk, prev, skb, state, tcp_skb_pcount(skb),
+	pcount = tcp_skb_pcount(skb);
+	if (tcp_skb_shift(prev, skb, pcount, len))
+		tcp_shifted_skb(sk, prev, skb, state, pcount,
 				len, mss, 0);
-	}
 
 out:
 	return prev;
@@ -2252,7 +2278,7 @@ static bool tcp_skb_spurious_retrans(const struct tcp_sock *tp,
  */
 static inline bool tcp_packet_delayed(const struct tcp_sock *tp)
 {
-	return !tp->retrans_stamp ||
+	return tp->retrans_stamp &&
 	       tcp_tsopt_ecr_before(tp, tp->retrans_stamp);
 }
 
@@ -2642,7 +2668,7 @@ static void tcp_process_loss(struct sock *sk, int flag, int num_dupack,
 	struct tcp_sock *tp = tcp_sk(sk);
 	bool recovered = !before(tp->snd_una, tp->high_seq);
 
-	if ((flag & FLAG_SND_UNA_ADVANCED) &&
+	if ((flag & FLAG_SND_UNA_ADVANCED || rcu_access_pointer(tp->fastopen_rsk)) &&
 	    tcp_try_undo_loss(sk, false))
 		return;
 
@@ -2966,7 +2992,7 @@ void tcp_rearm_rto(struct sock *sk)
 	/* If the retrans timer is currently being used by Fast Open
 	 * for SYN-ACK retrans purpose, stay put.
 	 */
-	if (tp->fastopen_rsk)
+	if (rcu_access_pointer(tp->fastopen_rsk))
 		return;
 
 	if (!tp->packets_out) {
@@ -3338,7 +3364,7 @@ static void tcp_rcv_nxt_update(struct tcp_sock *tp, u32 seq)
 
 	sock_owned_by_me((struct sock *)tp);
 	tp->bytes_received += delta;
-	tp->rcv_nxt = seq;
+	WRITE_ONCE(tp->rcv_nxt, seq);
 }
 
 /* Update our send window.
@@ -3521,7 +3547,7 @@ static void tcp_xmit_recovery(struct sock *sk, int rexmit)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
-	if (rexmit == REXMIT_NONE)
+	if (rexmit == REXMIT_NONE || sk->sk_state == TCP_SYN_SENT)
 		return;
 
 	if (unlikely(rexmit == 2)) {
@@ -3598,7 +3624,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 		icsk->icsk_retransmits = 0;
 
 #if IS_ENABLED(CONFIG_TLS_DEVICE)
-		if (static_branch_unlikely(&clean_acked_data_enabled))
+		if (static_branch_unlikely(&clean_acked_data_enabled.key))
 			if (icsk->icsk_clean_acked)
 				icsk->icsk_clean_acked(sk, ack);
 #endif
@@ -3758,6 +3784,49 @@ static void smc_parse_options(const struct tcphdr *th,
 #endif
 }
 
+/* Try to parse the MSS option from the TCP header. Return 0 on failure, clamped
+ * value on success.
+ */
+static u16 tcp_parse_mss_option(const struct tcphdr *th, u16 user_mss)
+{
+	const unsigned char *ptr = (const unsigned char *)(th + 1);
+	int length = (th->doff * 4) - sizeof(struct tcphdr);
+	u16 mss = 0;
+
+	while (length > 0) {
+		int opcode = *ptr++;
+		int opsize;
+
+		switch (opcode) {
+		case TCPOPT_EOL:
+			return mss;
+		case TCPOPT_NOP:	/* Ref: RFC 793 section 3.1 */
+			length--;
+			continue;
+		default:
+			if (length < 2)
+				return mss;
+			opsize = *ptr++;
+			if (opsize < 2) /* "silly options" */
+				return mss;
+			if (opsize > length)
+				return mss;	/* fail on partial options */
+			if (opcode == TCPOPT_MSS && opsize == TCPOLEN_MSS) {
+				u16 in_mss = get_unaligned_be16(ptr);
+
+				if (in_mss) {
+					if (user_mss && user_mss < in_mss)
+						in_mss = user_mss;
+					mss = in_mss;
+				}
+			}
+			ptr += opsize - 2;
+			length -= opsize;
+		}
+	}
+	return mss;
+}
+
 /* Look for tcp options. Normally only called on SYN and SYNACK packets.
  * But, this can also be called on packets in the established flow when
  * the fast version below fails.
@@ -3785,6 +3854,8 @@ void tcp_parse_options(const struct net *net,
 			length--;
 			continue;
 		default:
+			if (length < 2)
+				return;
 			opsize = *ptr++;
 			if (opsize < 2) /* "silly options" */
 				return;
@@ -4486,6 +4557,7 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
 	tp->pred_flags = 0;
 	inet_csk_schedule_ack(sk);
 
+	tp->rcv_ooopack += max_t(u16, 1, skb_shinfo(skb)->gso_segs);
 	NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPOFOQUEUE);
 	seq = TCP_SKB_CB(skb)->seq;
 	end_seq = TCP_SKB_CB(skb)->end_seq;
@@ -5286,7 +5358,7 @@ static void tcp_check_urg(struct sock *sk, const struct tcphdr *th)
 	}
 
 	tp->urg_data = TCP_URG_NOTYET;
-	tp->urg_seq = ptr;
+	WRITE_ONCE(tp->urg_seq, ptr);
 
 	/* Disable header prediction. */
 	tp->pred_flags = 0;
@@ -5647,6 +5719,32 @@ discard:
 }
 EXPORT_SYMBOL(tcp_rcv_established);
 
+void tcp_init_transfer(struct sock *sk, int bpf_op)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	tcp_mtup_init(sk);
+	icsk->icsk_af_ops->rebuild_header(sk);
+	tcp_init_metrics(sk);
+
+	/* Initialize the congestion window to start the transfer.
+	 * Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
+	 * retransmitted. In light of RFC6298 more aggressive 1sec
+	 * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
+	 * retransmission has occurred.
+	 */
+	if (tp->total_retrans > 1 && tp->undo_marker)
+		tp->snd_cwnd = 1;
+	else
+		tp->snd_cwnd = tcp_init_cwnd(tp, __sk_dst_get(sk));
+	tp->snd_cwnd_stamp = tcp_jiffies32;
+
+	tcp_call_bpf(sk, bpf_op, 0, NULL);
+	tcp_init_congestion_control(sk);
+	tcp_init_buffer_space(sk);
+}
+
 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
@@ -5716,6 +5814,10 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack,
 	tcp_fastopen_cache_set(sk, mss, cookie, syn_drop, try_exp);
 
 	if (data) { /* Retransmit unacked data in SYN */
+		if (tp->total_retrans)
+			tp->fastopen_client_fail = TFO_SYN_RETRANSMITTED;
+		else
+			tp->fastopen_client_fail = TFO_DATA_NOT_ACKED;
 		skb_rbtree_walk_from(data) {
 			if (__tcp_retransmit_skb(sk, data, 1))
 				break;
@@ -5748,6 +5850,21 @@ static void smc_check_reset_syn(struct tcp_sock *tp)
 #endif
 }
 
+static void tcp_try_undo_spurious_syn(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	u32 syn_stamp;
+
+	/* undo_marker is set when SYN or SYNACK times out. The timeout is
+	 * spurious if the ACK's timestamp option echo value matches the
+	 * original SYN timestamp.
+	 */
+	syn_stamp = tp->retrans_stamp;
+	if (tp->undo_marker && syn_stamp && tp->rx_opt.saw_tstamp &&
+	    syn_stamp == tp->rx_opt.rcv_tsecr)
+		tp->undo_marker = 0;
+}
+
 static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
 					 const struct tcphdr *th)
 {
@@ -5815,12 +5932,13 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
 		tcp_ecn_rcv_synack(tp, th);
 
 		tcp_init_wl(tp, TCP_SKB_CB(skb)->seq);
+		tcp_try_undo_spurious_syn(sk);
 		tcp_ack(sk, skb, FLAG_SLOWPATH);
 
 		/* Ok.. it's good. Set up sequence numbers and
 		 * move to established.
 		 */
-		tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
+		WRITE_ONCE(tp->rcv_nxt, TCP_SKB_CB(skb)->seq + 1);
 		tp->rcv_wup = TCP_SKB_CB(skb)->seq + 1;
 
 		/* RFC1323: The window in SYN & SYN/ACK segments is
@@ -5849,7 +5967,7 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
 		/* Remember, tcp_poll() does not lock socket!
 		 * Change state from SYN-SENT only after copied_seq
 		 * is initialized. */
-		tp->copied_seq = tp->rcv_nxt;
+		WRITE_ONCE(tp->copied_seq, tp->rcv_nxt);
 
 		smc_check_reset_syn(tp);
 
@@ -5923,8 +6041,8 @@ discard:
 			tp->tcp_header_len = sizeof(struct tcphdr);
 		}
 
-		tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
-		tp->copied_seq = tp->rcv_nxt;
+		WRITE_ONCE(tp->rcv_nxt, TCP_SKB_CB(skb)->seq + 1);
+		WRITE_ONCE(tp->copied_seq, tp->rcv_nxt);
 		tp->rcv_wup = TCP_SKB_CB(skb)->seq + 1;
 
 		/* RFC1323: The window in SYN & SYN/ACK segments is
@@ -5973,6 +6091,34 @@ reset_and_undo:
 	return 1;
 }
 
+static void tcp_rcv_synrecv_state_fastopen(struct sock *sk)
+{
+	struct request_sock *req;
+
+	tcp_try_undo_loss(sk, false);
+
+	/* Reset rtx states to prevent spurious retransmits_timed_out() */
+	tcp_sk(sk)->retrans_stamp = 0;
+	inet_csk(sk)->icsk_retransmits = 0;
+
+	/* Once we leave TCP_SYN_RECV or TCP_FIN_WAIT_1,
+	 * we no longer need req so release it.
+	 */
+	req = rcu_dereference_protected(tcp_sk(sk)->fastopen_rsk,
+					lockdep_sock_is_held(sk));
+	reqsk_fastopen_remove(sk, req, false);
+
+	/* Re-arm the timer because data may have been sent out.
+	 * This is similar to the regular data transmission case
+	 * when new data has just been ack'ed.
+	 *
+	 * (TFO) - we could try to be more aggressive and
+	 * retransmitting any data sooner based on when they
+	 * are sent out.
+	 */
+	tcp_rearm_rto(sk);
+}
+
 /*
  *	This function implements the receiving procedure of RFC 793 for
  *	all states except ESTABLISHED and TIME_WAIT.
@@ -6035,7 +6181,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 
 	tcp_mstamp_refresh(tp);
 	tp->rx_opt.saw_tstamp = 0;
-	req = tp->fastopen_rsk;
+	req = rcu_dereference_protected(tp->fastopen_rsk,
+					lockdep_sock_is_held(sk));
 	if (req) {
 		bool req_stolen;
 
@@ -6069,24 +6216,13 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 		if (!tp->srtt_us)
 			tcp_synack_rtt_meas(sk, req);
 
-		/* Once we leave TCP_SYN_RECV, we no longer need req
-		 * so release it.
-		 */
 		if (req) {
-			inet_csk(sk)->icsk_retransmits = 0;
-			reqsk_fastopen_remove(sk, req, false);
-			/* Re-arm the timer because data may have been sent out.
-			 * This is similar to the regular data transmission case
-			 * when new data has just been ack'ed.
-			 *
-			 * (TFO) - we could try to be more aggressive and
-			 * retransmitting any data sooner based on when they
-			 * are sent out.
-			 */
-			tcp_rearm_rto(sk);
+			tcp_rcv_synrecv_state_fastopen(sk);
 		} else {
+			tcp_try_undo_spurious_syn(sk);
+			tp->retrans_stamp = 0;
 			tcp_init_transfer(sk, BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB);
-			tp->copied_seq = tp->rcv_nxt;
+			WRITE_ONCE(tp->copied_seq, tp->rcv_nxt);
 		}
 		smp_mb();
 		tcp_set_state(sk, TCP_ESTABLISHED);
@@ -6119,16 +6255,9 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 	case TCP_FIN_WAIT1: {
 		int tmo;
 
-		/* If we enter the TCP_FIN_WAIT1 state and we are a
-		 * Fast Open socket and this is the first acceptable
-		 * ACK we have received, this would have acknowledged
-		 * our SYNACK so stop the SYNACK timer.
-		 */
-		if (req) {
-			/* We no longer need the request sock. */
-			reqsk_fastopen_remove(sk, req, false);
-			tcp_rearm_rto(sk);
-		}
+		if (req)
+			tcp_rcv_synrecv_state_fastopen(sk);
+
 		if (tp->snd_una != tp->write_seq)
 			break;
 
@@ -6263,6 +6392,11 @@ static inline void pr_drop_req(struct request_sock *req, __u16 port, int family)
  * congestion control: Linux DCTCP asserts ECT on all packets,
  * including SYN, which is most optimal solution; however,
  * others, such as FreeBSD do not.
+ *
+ * Exception: At least one of the reserved bits of the TCP header (th->res1) is
+ * set, indicating the use of a future TCP extension (such as AccECN). See
+ * RFC8311 §4.3 which updates RFC3168 to allow the development of such
+ * extensions.
  */
 static void tcp_ecn_create_request(struct request_sock *req,
 				   const struct sk_buff *skb,
@@ -6282,7 +6416,7 @@ static void tcp_ecn_create_request(struct request_sock *req,
 	ecn_ok_dst = dst_feature(dst, DST_FEATURE_ECN_MASK);
 	ecn_ok = net->ipv4.sysctl_tcp_ecn || ecn_ok_dst;
 
-	if ((!ect && ecn_ok) || tcp_ca_needs_ecn(listen_sk) ||
+	if (((!ect || th->res1) && ecn_ok) || tcp_ca_needs_ecn(listen_sk) ||
 	    (ecn_ok_dst & DST_FEATURE_ECN_CA) ||
 	    tcp_bpf_ca_needs_ecn((struct sock *)req))
 		inet_rsk(req)->ecn_ok = 1;
@@ -6298,7 +6432,7 @@ static void tcp_openreq_init(struct request_sock *req,
 	req->cookie_ts = 0;
 	tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
 	tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
-	tcp_rsk(req)->snt_synack = tcp_clock_us();
+	tcp_rsk(req)->snt_synack = 0;
 	tcp_rsk(req)->last_oow_ack_time = 0;
 	req->mss = rx_opt->mss_clamp;
 	req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
@@ -6343,9 +6477,7 @@ EXPORT_SYMBOL(inet_reqsk_alloc);
 /*
  * Return true if a syncookie should be sent
  */
-static bool tcp_syn_flood_action(const struct sock *sk,
-				 const struct sk_buff *skb,
-				 const char *proto)
+static bool tcp_syn_flood_action(const struct sock *sk, const char *proto)
 {
 	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
 	const char *msg = "Dropping request";
@@ -6365,7 +6497,7 @@ static bool tcp_syn_flood_action(const struct sock *sk,
 	    net->ipv4.sysctl_tcp_syncookies != 2 &&
 	    xchg(&queue->synflood_warned, 1) == 0)
 		net_info_ratelimited("%s: Possible SYN flooding on port %d. %s.  Check SNMP counters.\n",
-				     proto, ntohs(tcp_hdr(skb)->dest), msg);
+				     proto, sk->sk_num, msg);
 
 	return want_cookie;
 }
@@ -6387,6 +6519,36 @@ static void tcp_reqsk_record_syn(const struct sock *sk,
 	}
 }
 
+/* If a SYN cookie is required and supported, returns a clamped MSS value to be
+ * used for SYN cookie generation.
+ */
+u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops,
+			  const struct tcp_request_sock_ops *af_ops,
+			  struct sock *sk, struct tcphdr *th)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	u16 mss;
+
+	if (sock_net(sk)->ipv4.sysctl_tcp_syncookies != 2 &&
+	    !inet_csk_reqsk_queue_is_full(sk))
+		return 0;
+
+	if (!tcp_syn_flood_action(sk, rsk_ops->slab_name))
+		return 0;
+
+	if (sk_acceptq_is_full(sk)) {
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
+		return 0;
+	}
+
+	mss = tcp_parse_mss_option(th, tp->rx_opt.user_mss);
+	if (!mss)
+		mss = af_ops->mss_clamp;
+
+	return mss;
+}
+EXPORT_SYMBOL_GPL(tcp_get_syncookie_mss);
+
 int tcp_conn_request(struct request_sock_ops *rsk_ops,
 		     const struct tcp_request_sock_ops *af_ops,
 		     struct sock *sk, struct sk_buff *skb)
@@ -6408,7 +6570,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 	 */
 	if ((net->ipv4.sysctl_tcp_syncookies == 2 ||
 	     inet_csk_reqsk_queue_is_full(sk)) && !isn) {
-		want_cookie = tcp_syn_flood_action(sk, skb, rsk_ops->slab_name);
+		want_cookie = tcp_syn_flood_action(sk, rsk_ops->slab_name);
 		if (!want_cookie)
 			goto drop;
 	}
@@ -6502,8 +6664,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 			reqsk_fastopen_remove(fastopen_sk, req, false);
 			bh_unlock_sock(fastopen_sk);
 			sock_put(fastopen_sk);
-			reqsk_put(req);
-			goto drop;
+			goto drop_and_free;
 		}
 		sk->sk_data_ready(sk);
 		bh_unlock_sock(fastopen_sk);
@@ -6527,7 +6688,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 drop_and_release:
 	dst_release(dst);
 drop_and_free:
-	reqsk_free(req);
+	__reqsk_free(req);
 drop:
 	tcp_listendrop(sk);
 	return 0;