From 89278c9dc922272df921042aafa18311f3398c6c Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Sun, 11 May 2014 20:22:10 -0700 Subject: tcp: simplify fast open cookie processing Consolidate various cookie checking and generation code to simplify the fast open processing. The main goal is to reduce code duplication in tcp_v4_conn_request() for IPv6 support. Removes two experimental sysctl flags TFO_SERVER_ALWAYS and TFO_SERVER_COOKIE_NOT_CHKD used primarily for developmental debugging purposes. Signed-off-by: Yuchung Cheng Signed-off-by: Daniel Lee Signed-off-by: Jerry Chu Signed-off-by: Eric Dumazet Acked-by: Neal Cardwell Signed-off-by: David S. Miller --- net/ipv4/tcp_fastopen.c | 71 +++++++++++++++++++------------------------------ 1 file changed, 28 insertions(+), 43 deletions(-) (limited to 'net/ipv4/tcp_fastopen.c') diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c index 0606c91..5a98277 100644 --- a/net/ipv4/tcp_fastopen.c +++ b/net/ipv4/tcp_fastopen.c @@ -228,59 +228,44 @@ static bool tcp_fastopen_queue_check(struct sock *sk) return true; } +/* Returns true if we should perform Fast Open on the SYN. The cookie (foc) + * may be updated and return the client in the SYN-ACK later. E.g., Fast Open + * cookie request (foc->len == 0). + */ bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb, struct request_sock *req, - struct tcp_fastopen_cookie *foc, - struct tcp_fastopen_cookie *valid_foc) + struct tcp_fastopen_cookie *foc) { - bool skip_cookie = false; - - if (likely(!fastopen_cookie_present(foc))) { - /* See include/net/tcp.h for the meaning of these knobs */ - if ((sysctl_tcp_fastopen & TFO_SERVER_ALWAYS) || - ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD) && - (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1))) - skip_cookie = true; /* no cookie to validate */ - else - return false; - } - /* A FO option is present; bump the counter. */ - NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVE); + struct tcp_fastopen_cookie valid_foc = { .len = -1 }; + bool syn_data = TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1; - if ((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) == 0 || - !tcp_fastopen_queue_check(sk)) + if (!((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) && + (syn_data || foc->len >= 0) && + tcp_fastopen_queue_check(sk))) { + foc->len = -1; return false; - - if (skip_cookie) { - tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq; - return true; } - if (foc->len == TCP_FASTOPEN_COOKIE_SIZE) { - if ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_CHKED) == 0) { - tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, - ip_hdr(skb)->daddr, valid_foc); - if ((valid_foc->len != TCP_FASTOPEN_COOKIE_SIZE) || - memcmp(&foc->val[0], &valid_foc->val[0], - TCP_FASTOPEN_COOKIE_SIZE) != 0) - return false; - valid_foc->len = -1; - } - /* Acknowledge the data received from the peer. */ + if (syn_data && (sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD)) + goto fastopen; + + tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, + ip_hdr(skb)->daddr, &valid_foc); + + if (foc->len == TCP_FASTOPEN_COOKIE_SIZE && + foc->len == valid_foc.len && + !memcmp(foc->val, valid_foc.val, foc->len)) { +fastopen: tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq; + foc->len = -1; + NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVE); return true; - } else if (foc->len == 0) { /* Client requesting a cookie */ - tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, - ip_hdr(skb)->daddr, valid_foc); - NET_INC_STATS_BH(sock_net(sk), - LINUX_MIB_TCPFASTOPENCOOKIEREQD); - } else { - /* Client sent a cookie with wrong size. Treat it - * the same as invalid and return a valid one. - */ - tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, - ip_hdr(skb)->daddr, valid_foc); } + + NET_INC_STATS_BH(sock_net(sk), foc->len ? + LINUX_MIB_TCPFASTOPENPASSIVEFAIL : + LINUX_MIB_TCPFASTOPENCOOKIEREQD); + *foc = valid_foc; return false; } EXPORT_SYMBOL(tcp_fastopen_check); -- cgit v1.1