Merge remote-tracking branch 'regulator/fix/of' into tmp

[linux-beck.git] / net / ipv4 / tcp_input.c

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 181fc8234a529d5b6663f683e0da19e5ab17c1e8..18f97ca76b00223b25d0f6faed8a829c45fb95c8 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3552,6 +3552,24 @@ static bool tcp_process_frto(struct sock *sk, int flag)
        return false;
 }
 
+/* RFC 5961 7 [ACK Throttling] */
+static void tcp_send_challenge_ack(struct sock *sk)
+{
+       /* unprotected vars, we dont care of overwrites */
+       static u32 challenge_timestamp;
+       static unsigned int challenge_count;
+       u32 now = jiffies / HZ;
+
+       if (now != challenge_timestamp) {
+               challenge_timestamp = now;
+               challenge_count = 0;
+       }
+       if (++challenge_count <= sysctl_tcp_challenge_ack_limit) {
+               NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPCHALLENGEACK);
+               tcp_send_ack(sk);
+       }
+}
+
 /* This routine deals with incoming acks, but not outgoing ones. */
 static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 {
@@ -3571,8 +3589,14 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
        /* If the ack is older than previous acks
         * then we can probably ignore it.
         */
-       if (before(ack, prior_snd_una))
+       if (before(ack, prior_snd_una)) {
+               /* RFC 5961 5.2 [Blind Data Injection Attack].[Mitigation] */
+               if (before(ack, prior_snd_una - tp->max_window)) {
+                       tcp_send_challenge_ack(sk);
+                       return -1;
+               }
                goto old_ack;
+       }
 
        /* If the ack includes data we haven't sent yet, discard
         * this segment (RFC793 Section 3.9).
@@ -5244,23 +5268,6 @@ out:
 }
 #endif /* CONFIG_NET_DMA */
 
-static void tcp_send_challenge_ack(struct sock *sk)
-{
-       /* unprotected vars, we dont care of overwrites */
-       static u32 challenge_timestamp;
-       static unsigned int challenge_count;
-       u32 now = jiffies / HZ;
-
-       if (now != challenge_timestamp) {
-               challenge_timestamp = now;
-               challenge_count = 0;
-       }
-       if (++challenge_count <= sysctl_tcp_challenge_ack_limit) {
-               NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPCHALLENGEACK);
-               tcp_send_ack(sk);
-       }
-}
-
 /* Does PAWS and seqno based validation of an incoming segment, flags will
  * play significant role here.
  */
@@ -5536,6 +5543,9 @@ slow_path:
        if (len < (th->doff << 2) || tcp_checksum_complete_user(sk, skb))
                goto csum_error;
 
+       if (!th->ack && !th->rst)
+               goto discard;
+
        /*
         *      Standard slow path.
         */
@@ -5544,7 +5554,7 @@ slow_path:
                return 0;
 
 step5:
-       if (th->ack && tcp_ack(sk, skb, FLAG_SLOWPATH) < 0)
+       if (tcp_ack(sk, skb, FLAG_SLOWPATH) < 0)
                goto discard;
 
        /* ts_recent update must be made after we are sure that the packet
@@ -5977,11 +5987,15 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
                if (tcp_check_req(sk, skb, req, NULL, true) == NULL)
                        goto discard;
        }
+
+       if (!th->ack && !th->rst)
+               goto discard;
+
        if (!tcp_validate_incoming(sk, skb, th, 0))
                return 0;
 
        /* step 5: check the ACK field */
-       if (th->ack) {
+       if (true) {
                int acceptable = tcp_ack(sk, skb, FLAG_SLOWPATH) > 0;
 
                switch (sk->sk_state) {
@@ -5992,7 +6006,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
                                 */
                                if (req) {
                                        tcp_synack_rtt_meas(sk, req);
-                                       tp->total_retrans = req->retrans;
+                                       tp->total_retrans = req->num_retrans;
 
                                        reqsk_fastopen_remove(sk, req, false);
                                } else {
@@ -6131,8 +6145,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
                        }
                        break;
                }
-       } else
-               goto discard;
+       }
 
        /* ts_recent update must be made after we are sure that the packet
         * is in window.