diff options
| author |   Neal Cardwell <ncardwell@google.com> | 2015-02-06 16:04:39 -0500 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2015-02-08 01:03:12 -0800 |
| commit | a9b2c06dbef48ed31cff1764c5ce824829106f4f (patch) | |
| tree | 7e1dc6d03d3f2ba41a3a867fad3bf59c49665599 /include/net | |
| parent | tcp: helpers to mitigate ACK loops by rate-limiting out-of-window dupacks (diff) | |
| download | linux-dev-a9b2c06dbef48ed31cff1764c5ce824829106f4f.tar.xz linux-dev-a9b2c06dbef48ed31cff1764c5ce824829106f4f.zip | |
tcp: mitigate ACK loops for connections as tcp_request_sock
In the SYN_RECV state, where the TCP connection is represented by
tcp_request_sock, we now rate-limit SYNACKs in response to a client's
retransmitted SYNs: we do not send a SYNACK in response to client SYN
if it has been less than sysctl_tcp_invalid_ratelimit (default 500ms)
since we last sent a SYNACK in response to a client's retransmitted
SYN.
This allows the vast majority of legitimate client connections to
proceed unimpeded, even for the most aggressive platforms, iOS and
MacOS, which actually retransmit SYNs 1-second intervals for several
times in a row. They use SYN RTO timeouts following the progression:
1,1,1,1,1,2,4,8,16,32.
Reported-by: Avery Fay <avery@mixpanel.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net')
| -rw-r--r-- | include/net/tcp.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h index b81f45c67b2e..da4196fb78db 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1145,6 +1145,7 @@ static inline void tcp_openreq_init(struct request_sock *req, tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq; tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1; tcp_rsk(req)->snt_synack = tcp_time_stamp; + tcp_rsk(req)->last_oow_ack_time = 0; req->mss = rx_opt->mss_clamp; req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0; ireq->tstamp_ok = rx_opt->tstamp_ok; |