From c7d13c8faa74f4e8ef191f88a252cefab6805b38 Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Wed, 16 Jan 2019 15:05:31 -0800 Subject: [PATCH] tcp: properly track retry time on passive Fast Open This patch addresses a corner issue on timeout behavior of a passive Fast Open socket. A passive Fast Open server may write and close the socket when it is re-trying SYN-ACK to complete the handshake. After the handshake is completely, the server does not properly stamp the recovery start time (tp->retrans_stamp is 0), and the socket may abort immediately on the very first FIN timeout, instead of retying until it passes the system or user specified limit. Signed-off-by: Yuchung Cheng Signed-off-by: Eric Dumazet Reviewed-by: Neal Cardwell Reviewed-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller --- net/ipv4/tcp_timer.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index 1e61f0bd6e24..074de38bafbd 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -378,6 +378,7 @@ static void tcp_fastopen_synack_timer(struct sock *sk) struct inet_connection_sock *icsk = inet_csk(sk); int max_retries = icsk->icsk_syn_retries ? : sock_net(sk)->ipv4.sysctl_tcp_synack_retries + 1; /* add one more retry for fastopen */ + struct tcp_sock *tp = tcp_sk(sk); struct request_sock *req; req = tcp_sk(sk)->fastopen_rsk; @@ -395,6 +396,8 @@ static void tcp_fastopen_synack_timer(struct sock *sk) inet_rtx_syn_ack(sk, req); req->num_timeout++; icsk->icsk_retransmits++; + if (!tp->retrans_stamp) + tp->retrans_stamp = tcp_time_stamp(tp); inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX); } -- 2.30.2