tcp: implement RFC 5961 4.2

[pandora-kernel.git] / net / ipv4 / tcp_input.c

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index a0d3b88..0b9d8d4 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5263,8 +5263,8 @@ static void tcp_send_challenge_ack(struct sock *sk)
 /* Does PAWS and seqno based validation of an incoming segment, flags will
  * play significant role here.
  */
-static int tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
-                             const struct tcphdr *th, int syn_inerr)
+static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
+                                 const struct tcphdr *th, int syn_inerr)
 {
        const u8 *hash_location;
        struct tcp_sock *tp = tcp_sk(sk);
@@ -5316,20 +5316,22 @@ static int tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
 
        /* step 3: check security and precedence [ignored] */
 
-       /* step 4: Check for a SYN in window. */
-       if (th->syn && !before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) {
+       /* step 4: Check for a SYN
+        * RFC 5691 4.2 : Send a challenge ack
+        */
+       if (th->syn) {
                if (syn_inerr)
                        TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
-               NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONSYN);
-               tcp_reset(sk);
-               return -1;
+               NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSYNCHALLENGE);
+               tcp_send_challenge_ack(sk);
+               goto discard;
        }
 
-       return 1;
+       return true;
 
 discard:
        __kfree_skb(skb);
-       return 0;
+       return false;
 }
 
 /*
@@ -5359,7 +5361,6 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
                        const struct tcphdr *th, unsigned int len)
 {
        struct tcp_sock *tp = tcp_sk(sk);
-       int res;
 
        /*
         *      Header prediction.
@@ -5539,9 +5540,8 @@ slow_path:
         *      Standard slow path.
         */
 
-       res = tcp_validate_incoming(sk, skb, th, 1);
-       if (res <= 0)
-               return -res;
+       if (!tcp_validate_incoming(sk, skb, th, 1))
+               return 0;
 
 step5:
        if (th->ack && tcp_ack(sk, skb, FLAG_SLOWPATH) < 0)
@@ -5851,7 +5851,6 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
        struct tcp_sock *tp = tcp_sk(sk);
        struct inet_connection_sock *icsk = inet_csk(sk);
        int queued = 0;
-       int res;
 
        tp->rx_opt.saw_tstamp = 0;
 
@@ -5906,9 +5905,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
                return 0;
        }
 
-       res = tcp_validate_incoming(sk, skb, th, 0);
-       if (res <= 0)
-               return -res;
+       if (!tcp_validate_incoming(sk, skb, th, 0))
+               return 0;
 
        /* step 5: check the ACK field */
        if (th->ack) {