diff options
| author | Yuchung Cheng <ycheng@google.com> | 2012-07-19 06:43:11 (GMT) |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-07-19 18:02:03 (GMT) |
| commit | 67da22d23fa6f3324e03bcd0580b914b2e4afbf3 (patch) | |
| tree | e794826d1dd7e30cf0885cbe93f22bc050c62359 /net | |
| parent | aab4874355679c70f93993cf3b3fd74643b9ac33 (diff) | |
| download | linux-67da22d23fa6f3324e03bcd0580b914b2e4afbf3.tar.xz | |
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 <ycheng@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_input.c | 8 | ||||
| -rw-r--r-- | net/ipv4/tcp_output.c | 6 |
2 files changed, 11 insertions, 3 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index c49a4fc..e67d685 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5650,7 +5650,7 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack, struct tcp_fastopen_cookie *cookie) { struct tcp_sock *tp = tcp_sk(sk); - struct sk_buff *data = tcp_write_queue_head(sk); + struct sk_buff *data = tp->syn_data ? tcp_write_queue_head(sk) : NULL; u16 mss = tp->rx_opt.mss_clamp; bool syn_drop; @@ -5665,6 +5665,9 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack, mss = opt.mss_clamp; } + if (!tp->syn_fastopen) /* Ignore an unsolicited cookie */ + cookie->len = -1; + /* The SYN-ACK neither has cookie nor acknowledges the data. Presumably * the remote receives only the retransmitted (regular) SYNs: either * the original SYN-data or the corresponding SYN-ACK is lost. @@ -5816,7 +5819,8 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, tcp_finish_connect(sk, skb); - if (tp->syn_fastopen && tcp_rcv_fastopen_synack(sk, skb, &foc)) + if ((tp->syn_fastopen || tp->syn_data) && + tcp_rcv_fastopen_synack(sk, skb, &foc)) return -1; if (sk->sk_write_pending || diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index c5cfd5e..27a32ac 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; } |