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TCPCT part 1g: Responder Cookie => Initiator

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Parse incoming TCP_COOKIE option(s).

Calculate <SYN,ACK> TCP_COOKIE option.

Send optional <SYN,ACK> data.

This is a significantly revised implementation of an earlier (year-old)
patch that no longer applies cleanly, with permission of the original
author (Adam Langley):

    http://thread.gmane.org/gmane.linux.network/102586

Requires:
   TCPCT part 1a: add request_values parameter for sending SYNACK
   TCPCT part 1b: generate Responder Cookie secret
   TCPCT part 1c: sysctl_tcp_cookie_size, socket option TCP_COOKIE_TRANSACTIONS
   TCPCT part 1d: define TCP cookie option, extend existing struct's
   TCPCT part 1e: implement socket option TCP_COOKIE_TRANSACTIONS
   TCPCT part 1f: Initiator Cookie => Responder

Signed-off-by: William.Allen.Simpson@gmail.com
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
William Allen Simpson
2009-12-02 18:25:27 +00:00
committed by David S. Miller
parent bd0388ae77
commit 4957faade1
8 changed files with 259 additions and 43 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
net/ipv4/syncookies.c
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@@ -253,6 +253,8 @@ EXPORT_SYMBOL(cookie_check_timestamp);
struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
struct ip_options *opt)
{
struct tcp_options_received tcp_opt;
u8 *hash_location;
struct inet_request_sock *ireq;
struct tcp_request_sock *treq;
struct tcp_sock *tp = tcp_sk(sk);
@@ -263,7 +265,6 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
int mss;
struct rtable *rt;
__u8 rcv_wscale;
struct tcp_options_received tcp_opt;
if (!sysctl_tcp_syncookies || !th->ack)
goto out;
@@ -341,7 +342,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
/* check for timestamp cookie support */
memset(&tcp_opt, 0, sizeof(tcp_opt));
tcp_parse_options(skb, &tcp_opt, 0, &rt->u.dst);
tcp_parse_options(skb, &tcp_opt, &hash_location, 0, &rt->u.dst);
if (tcp_opt.saw_tstamp)
cookie_check_timestamp(&tcp_opt);