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tcp: simplify fast open cookie processing

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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>
This commit is contained in:
Yuchung Cheng
2014-05-11 20:22:10 -07:00
committed by David S. Miller
parent 5b7ed0892f
commit 89278c9dc9
5 changed files with 33 additions and 64 deletions
Download Patch File Download Diff File Expand all files Collapse all files

71
net/ipv4/tcp_fastopen.c
View File

@@ -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;
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);