From 67da22d23fa6f3324e03bcd0580b914b2e4afbf3 Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Thu, 19 Jul 2012 06:43:11 +0000 Subject: net-tcp: Fast Open client - cookie-less mode In trusted networks, e.g., intranet, data-center, the client does not need to use Fast Open cookie to mitigate DoS attacks. In cookie-less mode, sendmsg() with MSG_FASTOPEN flag will send SYN-data regardless of cookie availability. Signed-off-by: Yuchung Cheng Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'net/ipv4/tcp_output.c') diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index c5cfd5ec3184..27a32acfdb62 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2864,6 +2864,7 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) struct sk_buff *syn_data = NULL, *data; unsigned long last_syn_loss = 0; + tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ tcp_fastopen_cache_get(sk, &tp->rx_opt.mss_clamp, &fo->cookie, &syn_loss, &last_syn_loss); /* Recurring FO SYN losses: revert to regular handshake temporarily */ @@ -2873,7 +2874,9 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) goto fallback; } - if (fo->cookie.len <= 0) + if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) + fo->cookie.len = -1; + else if (fo->cookie.len <= 0) goto fallback; /* MSS for SYN-data is based on cached MSS and bounded by PMTU and @@ -2916,6 +2919,7 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) fo->copied = data->len; if (tcp_transmit_skb(sk, syn_data, 0, sk->sk_allocation) == 0) { + tp->syn_data = (fo->copied > 0); NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENACTIVE); goto done; } -- cgit v1.2.3-55-g7522