ipv6: tcp: fix tcp_v6_conn_request()

Since linux 2.6.26 (commit c6aefafb7ec6 : Add IPv6 support to TCP SYN
cookies), we can drop a SYN packet reusing a TIME_WAIT socket.

(As a matter of fact we fail to send the SYNACK answer)

As the client resends its SYN packet after a one second timeout, we
accept it, because first packet removed the TIME_WAIT socket before
being dropped.

This probably explains why nobody ever noticed or complained.

Reported-by: Jesse Young <jlyo@jlyo.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 6 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 36131d122a6f..2dea4bb7b54a 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1255,6 +1255,13 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
         if (!want_cookie || tmp_opt.tstamp_ok)
                 TCP_ECN_create_request(req, tcp_hdr(skb));
 
+        treq->iif = sk->sk_bound_dev_if;
+
+        /* So that link locals have meaning */
+        if (!sk->sk_bound_dev_if &&
+            ipv6_addr_type(&treq->rmt_addr) & IPV6_ADDR_LINKLOCAL)
+                treq->iif = inet6_iif(skb);
+
         if (!isn) {
                 struct inet_peer *peer = NULL;
 
@@ -1264,12 +1271,6 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
                         atomic_inc(&skb->users);
                         treq->pktopts = skb;
                 }
-                treq->iif = sk->sk_bound_dev_if;
-
-                /* So that link locals have meaning */
-                if (!sk->sk_bound_dev_if &&
-                    ipv6_addr_type(&treq->rmt_addr) & IPV6_ADDR_LINKLOCAL)
-                        treq->iif = inet6_iif(skb);
 
                 if (want_cookie) {
                         isn = cookie_v6_init_sequence(sk, skb, &req->mss);