Merge branch 'tcp_fastopen_server'

Jerry Chu says:

====================
This patch series provides the server (passive open) side code
for TCP Fast Open. Together with the earlier client side patches
it completes the TCP Fast Open implementation.

The server side Fast Open code accepts data carried in the SYN
packet with a valid Fast Open cookie, and passes it to the
application right away, allowing application to send back response
data, all before TCP's 3-way handshake finishes.

A simple cookie scheme together with capping the number of
outstanding TFO requests (still in TCP_SYN_RECV state) to a limit
per listener forms the main line of defense against spoofed SYN
attacks.

For more details about TCP Fast Open see our IETF internet draft
at http://www.ietf.org/id/draft-ietf-tcpm-fastopen-01.txt
and a research paper at
http://conferences.sigcomm.org/co-next/2011/papers/1569470463.pdf

A prototype implementation was first developed by Sivasankar
Radhakrishnan (sivasankar@cs.ucsd.edu).

A patch based on an older version of Linux kernel has been
undergoing internal tests at Google for the past few months.

Jerry Chu (3):
  tcp: TCP Fast Open Server - header & support functions
  tcp: TCP Fast Open Server - support TFO listeners
  tcp: TCP Fast Open Server - main code path
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 46 insertions, 3 deletions

diff --git a/include/linux/snmp.h b/include/linux/snmp.h
index ad6e3a6bf9fb..fdfba235f9f1 100644
--- a/include/linux/snmp.h
+++ b/include/linux/snmp.h
@@ -241,6 +241,10 @@ enum
         LINUX_MIB_TCPCHALLENGEACK,              /* TCPChallengeACK */
         LINUX_MIB_TCPSYNCHALLENGE,              /* TCPSYNChallenge */
         LINUX_MIB_TCPFASTOPENACTIVE,            /* TCPFastOpenActive */
+        LINUX_MIB_TCPFASTOPENPASSIVE,           /* TCPFastOpenPassive*/
+        LINUX_MIB_TCPFASTOPENPASSIVEFAIL,       /* TCPFastOpenPassiveFail */
+        LINUX_MIB_TCPFASTOPENLISTENOVERFLOW,    /* TCPFastOpenListenOverflow */
+        LINUX_MIB_TCPFASTOPENCOOKIEREQD,        /* TCPFastOpenCookieReqd */
         __LINUX_MIB_MAX
 };
 
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index eb125a4c30b3..ae46df590629 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -110,6 +110,7 @@ enum {
 #define TCP_REPAIR_QUEUE        20
 #define TCP_QUEUE_SEQ           21
 #define TCP_REPAIR_OPTIONS      22
+#define TCP_FASTOPEN            23      /* Enable FastOpen on listeners */
 
 struct tcp_repair_opt {
         __u32   opt_code;
@@ -246,6 +247,7 @@ static inline unsigned int tcp_optlen(const struct sk_buff *skb)
 /* TCP Fast Open */
 #define TCP_FASTOPEN_COOKIE_MIN 4       /* Min Fast Open Cookie size in bytes */
 #define TCP_FASTOPEN_COOKIE_MAX 16      /* Max Fast Open Cookie size in bytes */
+#define TCP_FASTOPEN_COOKIE_SIZE 8      /* the size employed by this impl. */
 
 /* TCP Fast Open Cookie as stored in memory */
 struct tcp_fastopen_cookie {
@@ -312,9 +314,14 @@ struct tcp_request_sock {
         /* Only used by TCP MD5 Signature so far. */
         const struct tcp_request_sock_ops *af_specific;
 #endif
+        struct sock                     *listener; /* needed for TFO */
         u32                             rcv_isn;
         u32                             snt_isn;
         u32                             snt_synack; /* synack sent time */
+        u32                             rcv_nxt; /* the ack # by SYNACK. For
+                                                  * FastOpen it's the seq#
+                                                  * after data-in-SYN.
+                                                  */
 };
 
 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
@@ -505,14 +512,18 @@ struct tcp_sock {
         struct tcp_md5sig_info  __rcu *md5sig_info;
 #endif
 
-/* TCP fastopen related information */
-        struct tcp_fastopen_request *fastopen_req;
-
         /* When the cookie options are generated and exchanged, then this
          * object holds a reference to them (cookie_values->kref).  Also
          * contains related tcp_cookie_transactions fields.
          */
         struct tcp_cookie_values  *cookie_values;
+
+/* TCP fastopen related information */
+        struct tcp_fastopen_request *fastopen_req;
+        /* fastopen_rsk points to request_sock that resulted in this big
+         * socket. Used to retransmit SYNACKs etc.
+         */
+        struct request_sock *fastopen_rsk;
 };
 
 enum tsq_flags {
@@ -552,6 +563,34 @@ static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
         return (struct tcp_timewait_sock *)sk;
 }
 
+static inline bool tcp_passive_fastopen(const struct sock *sk)
+{
+        return (sk->sk_state == TCP_SYN_RECV &&
+                tcp_sk(sk)->fastopen_rsk != NULL);
+}
+
+static inline bool fastopen_cookie_present(struct tcp_fastopen_cookie *foc)
+{
+        return foc->len != -1;
+}
+
+static inline int fastopen_init_queue(struct sock *sk, int backlog)
+{
+        struct request_sock_queue *queue =
+            &inet_csk(sk)->icsk_accept_queue;
+
+        if (queue->fastopenq == NULL) {
+                queue->fastopenq = kzalloc(
+                    sizeof(struct fastopen_queue),
+                    sk->sk_allocation);
+                if (queue->fastopenq == NULL)
+                        return -ENOMEM;
+                spin_lock_init(&queue->fastopenq->lock);
+        }
+        queue->fastopenq->max_qlen = backlog;
+        return 0;
+}
+
 #endif  /* __KERNEL__ */
 
 #endif  /* _LINUX_TCP_H */