diff options
| author | Yuchung Cheng <ycheng@google.com> | 2015-02-09 12:35:23 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-02-09 14:26:55 -0800 |
| commit | 531c94a9681b8c253fd0490a4ca8bbe01a38c78b (patch) | |
| tree | f15abdcc7f4af03a3cd80e234e68acc0601a7c5d /net/ipv4/tcp_fastopen.c | |
| parent | 223ab8ffeb0c7883304d66e5891004643b0e1c0b (diff) | |
| download | lwn-531c94a9681b8c253fd0490a4ca8bbe01a38c78b.tar.gz lwn-531c94a9681b8c253fd0490a4ca8bbe01a38c78b.zip | |
tcp: don't include Fast Open option in SYN-ACK on pure SYN-data
If a server has enabled Fast Open and it receives a pure SYN-data
packet (without a Fast Open option), it won't accept the data but it
incorrectly returns a SYN-ACK with a Fast Open cookie and also
increments the SNMP stat LINUX_MIB_TCPFASTOPENPASSIVEFAIL.
This patch makes the server include a Fast Open cookie in SYN-ACK
only if the SYN has some Fast Open option (i.e., when client
requests or presents a cookie).
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_fastopen.c')
| -rw-r--r-- | net/ipv4/tcp_fastopen.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c index 815c85e3b1e0..53db2c309572 100644 --- a/net/ipv4/tcp_fastopen.c +++ b/net/ipv4/tcp_fastopen.c @@ -255,6 +255,9 @@ bool tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, struct tcp_fastopen_cookie valid_foc = { .len = -1 }; bool syn_data = TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1; + if (foc->len == 0) /* Client requests a cookie */ + NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENCOOKIEREQD); + if (!((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) && (syn_data || foc->len >= 0) && tcp_fastopen_queue_check(sk))) { @@ -265,7 +268,8 @@ bool tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, if (syn_data && (sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD)) goto fastopen; - if (tcp_fastopen_cookie_gen(req, skb, &valid_foc) && + if (foc->len >= 0 && /* Client presents or requests a cookie */ + tcp_fastopen_cookie_gen(req, skb, &valid_foc) && foc->len == TCP_FASTOPEN_COOKIE_SIZE && foc->len == valid_foc.len && !memcmp(foc->val, valid_foc.val, foc->len)) { @@ -284,11 +288,10 @@ fastopen: LINUX_MIB_TCPFASTOPENPASSIVE); return true; } - } + NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVEFAIL); + } else if (foc->len > 0) /* Client presents an invalid cookie */ + NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVEFAIL); - NET_INC_STATS_BH(sock_net(sk), foc->len ? - LINUX_MIB_TCPFASTOPENPASSIVEFAIL : - LINUX_MIB_TCPFASTOPENCOOKIEREQD); *foc = valid_foc; return false; } |