tcp: ipv6: support RFC 6069 (TCP-LD)

Make tcp_ld_RTO_revert() helper available to IPv6, and
implement RFC 6069 :

Quoting this RFC :

3. Connectivity Disruption Indication

   For Internet Protocol version 6 (IPv6) [RFC2460], the counterpart of
   the ICMP destination unreachable message of code 0 (net unreachable)
   and of code 1 (host unreachable) is the ICMPv6 destination
   unreachable message of code 0 (no route to destination) [RFC4443].
   As with IPv4, a router should generate an ICMPv6 destination
   unreachable message of code 0 in response to a packet that cannot be
   delivered to its destination address because it lacks a matching
   entry in its routing table.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/tcp.h b/include/net/tcp.h
index b681338..66e4b83 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -437,6 +437,7 @@ u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops,
 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
 void tcp_v4_mtu_reduced(struct sock *sk);
 void tcp_req_err(struct sock *sk, u32 seq, bool abort);
+void tcp_ld_RTO_revert(struct sock *sk, u32 seq);
 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
 struct sock *tcp_create_openreq_child(const struct sock *sk,
                                      struct request_sock *req,

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 4eef5b8..ad6435b 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -404,7 +404,7 @@ void tcp_req_err(struct sock *sk, u32 seq, bool abort)
 EXPORT_SYMBOL(tcp_req_err);
 
 /* TCP-LD (RFC 6069) logic */
-static void tcp_ld_RTO_revert(struct sock *sk, u32 seq)
+void tcp_ld_RTO_revert(struct sock *sk, u32 seq)
 {
        struct inet_connection_sock *icsk = inet_csk(sk);
        struct tcp_sock *tp = tcp_sk(sk);
@@ -441,6 +441,7 @@ static void tcp_ld_RTO_revert(struct sock *sk, u32 seq)
                tcp_retransmit_timer(sk);
        }
 }
+EXPORT_SYMBOL(tcp_ld_RTO_revert);
 
 /*
  * This routine is called by the ICMP module when it gets some

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 01a6f51..b7415ca 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -473,6 +473,15 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                } else
                        sk->sk_err_soft = err;
                goto out;
+       case TCP_LISTEN:
+               break;
+       default:
+               /* check if this ICMP message allows revert of backoff.
+                * (see RFC 6069)
+                */
+               if (!fastopen && type == ICMPV6_DEST_UNREACH &&
+                   code == ICMPV6_NOROUTE)
+                       tcp_ld_RTO_revert(sk, seq);
        }
 
        if (!sock_owned_by_user(sk) && np->recverr) {