Merge branch 'tcp-change-reaction-to-ICMP'

Eric Dumazet says:

====================
tcp: change reaction to ICMP messages

ICMP[v6] messages received for a socket in TCP_SYN_SENT currently abort
the connection attempt, in violation of standards.

This series changes our stack to adhere to RFC 6069 and RFC 1122
(4.2.3.9)

====================

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 14 insertions, 5 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 5f693bbd578d..86cc6d36f818 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -482,6 +482,7 @@ int tcp_v4_err(struct sk_buff *skb, u32 info)
 	const int code = icmp_hdr(skb)->code;
 	struct sock *sk;
 	struct request_sock *fastopen;
+	bool harderr = false;
 	u32 seq, snd_una;
 	int err;
 	struct net *net = dev_net(skb->dev);
@@ -555,6 +556,7 @@ int tcp_v4_err(struct sk_buff *skb, u32 info)
 		goto out;
 	case ICMP_PARAMETERPROB:
 		err = EPROTO;
+		harderr = true;
 		break;
 	case ICMP_DEST_UNREACH:
 		if (code > NR_ICMP_UNREACH)
@@ -579,6 +581,7 @@ int tcp_v4_err(struct sk_buff *skb, u32 info)
 		}
 
 		err = icmp_err_convert[code].errno;
+		harderr = icmp_err_convert[code].fatal;
 		/* check if this ICMP message allows revert of backoff.
 		 * (see RFC 6069)
 		 */
@@ -604,6 +607,9 @@ int tcp_v4_err(struct sk_buff *skb, u32 info)
 
 		ip_icmp_error(sk, skb, err, th->dest, info, (u8 *)th);
 
+		if (!harderr)
+			break;
+
 		if (!sock_owned_by_user(sk)) {
 			WRITE_ONCE(sk->sk_err, err);
 
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 1f9f6c1c196b..d1ad20ce1c8c 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -626,7 +626,6 @@ void tcp_retransmit_timer(struct sock *sk)
 	 * implemented ftp to mars will work nicely. We will have to fix
 	 * the 120 second clamps though!
 	 */
-	icsk->icsk_backoff++;
 
 out_reset_timer:
 	/* If stream is thin, use linear timeouts. Since 'icsk_backoff' is
@@ -647,11 +646,12 @@ out_reset_timer:
 				       tcp_rto_min(sk),
 				       TCP_RTO_MAX);
 	} else if (sk->sk_state != TCP_SYN_SENT ||
-		   icsk->icsk_backoff >
+		   tp->total_rto >
 		   READ_ONCE(net->ipv4.sysctl_tcp_syn_linear_timeouts)) {
 		/* Use normal (exponential) backoff unless linear timeouts are
 		 * activated.
 		 */
+		icsk->icsk_backoff++;
 		icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
 	}
 	inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 937a02c2e534..43deda49cc52 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -381,7 +381,7 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	struct tcp_sock *tp;
 	__u32 seq, snd_una;
 	struct sock *sk;
-	bool fatal;
+	bool harderr;
 	int err;
 
 	sk = __inet6_lookup_established(net, net->ipv4.tcp_death_row.hashinfo,
@@ -402,9 +402,9 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 		return 0;
 	}
 	seq = ntohl(th->seq);
-	fatal = icmpv6_err_convert(type, code, &err);
+	harderr = icmpv6_err_convert(type, code, &err);
 	if (sk->sk_state == TCP_NEW_SYN_RECV) {
-		tcp_req_err(sk, seq, fatal);
+		tcp_req_err(sk, seq, harderr);
 		return 0;
 	}
 
@@ -489,6 +489,9 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 
 		ipv6_icmp_error(sk, skb, err, th->dest, ntohl(info), (u8 *)th);
 
+		if (!harderr)
+			break;
+
 		if (!sock_owned_by_user(sk)) {
 			WRITE_ONCE(sk->sk_err, err);
 			sk_error_report(sk);		/* Wake people up to see the error (see connect in sock.c) */