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 <ycheng@google.com>
Signed-off-by: Daniel Lee <longinus00@gmail.com>
Signed-off-by: Jerry Chu <hkchu@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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 @@
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;
+ struct tcp_fastopen_cookie valid_foc = { .len = -1 };
+ bool syn_data = TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1;
- 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);
-
- 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) {
+ 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;
}
- 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. */
- tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
- 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);