1 files changed, 43 insertions, 24 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 0640453fce54..1efacbe948da 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4764,8 +4764,8 @@ static void tcp_ofo_queue(struct sock *sk)
 	}
 }
 
-static bool tcp_prune_ofo_queue(struct sock *sk);
-static int tcp_prune_queue(struct sock *sk);
+static bool tcp_prune_ofo_queue(struct sock *sk, const struct sk_buff *in_skb);
+static int tcp_prune_queue(struct sock *sk, const struct sk_buff *in_skb);
 
 static int tcp_try_rmem_schedule(struct sock *sk, struct sk_buff *skb,
 				 unsigned int size)
@@ -4773,11 +4773,11 @@ static int tcp_try_rmem_schedule(struct sock *sk, struct sk_buff *skb,
 	if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
 	    !sk_rmem_schedule(sk, skb, size)) {
 
-		if (tcp_prune_queue(sk) < 0)
+		if (tcp_prune_queue(sk, skb) < 0)
 			return -1;
 
 		while (!sk_rmem_schedule(sk, skb, size)) {
-			if (!tcp_prune_ofo_queue(sk))
+			if (!tcp_prune_ofo_queue(sk, skb))
 				return -1;
 		}
 	}
@@ -5329,6 +5329,8 @@ new_range:
  * Clean the out-of-order queue to make room.
  * We drop high sequences packets to :
  * 1) Let a chance for holes to be filled.
+ *    This means we do not drop packets from ooo queue if their sequence
+ *    is before incoming packet sequence.
  * 2) not add too big latencies if thousands of packets sit there.
  *    (But if application shrinks SO_RCVBUF, we could still end up
  *     freeing whole queue here)
@@ -5336,24 +5338,31 @@ new_range:
  *
  * Return true if queue has shrunk.
  */
-static bool tcp_prune_ofo_queue(struct sock *sk)
+static bool tcp_prune_ofo_queue(struct sock *sk, const struct sk_buff *in_skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct rb_node *node, *prev;
+	bool pruned = false;
 	int goal;
 
 	if (RB_EMPTY_ROOT(&tp->out_of_order_queue))
 		return false;
 
-	NET_INC_STATS(sock_net(sk), LINUX_MIB_OFOPRUNED);
 	goal = sk->sk_rcvbuf >> 3;
 	node = &tp->ooo_last_skb->rbnode;
+
 	do {
+		struct sk_buff *skb = rb_to_skb(node);
+
+		/* If incoming skb would land last in ofo queue, stop pruning. */
+		if (after(TCP_SKB_CB(in_skb)->seq, TCP_SKB_CB(skb)->seq))
+			break;
+		pruned = true;
 		prev = rb_prev(node);
 		rb_erase(node, &tp->out_of_order_queue);
-		goal -= rb_to_skb(node)->truesize;
-		tcp_drop_reason(sk, rb_to_skb(node),
-				SKB_DROP_REASON_TCP_OFO_QUEUE_PRUNE);
+		goal -= skb->truesize;
+		tcp_drop_reason(sk, skb, SKB_DROP_REASON_TCP_OFO_QUEUE_PRUNE);
+		tp->ooo_last_skb = rb_to_skb(prev);
 		if (!prev || goal <= 0) {
 			if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
 			    !tcp_under_memory_pressure(sk))
@@ -5362,16 +5371,18 @@ static bool tcp_prune_ofo_queue(struct sock *sk)
 		}
 		node = prev;
 	} while (node);
-	tp->ooo_last_skb = rb_to_skb(prev);
 
-	/* Reset SACK state.  A conforming SACK implementation will
-	 * do the same at a timeout based retransmit.  When a connection
-	 * is in a sad state like this, we care only about integrity
-	 * of the connection not performance.
-	 */
-	if (tp->rx_opt.sack_ok)
-		tcp_sack_reset(&tp->rx_opt);
-	return true;
+	if (pruned) {
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_OFOPRUNED);
+		/* Reset SACK state.  A conforming SACK implementation will
+		 * do the same at a timeout based retransmit.  When a connection
+		 * is in a sad state like this, we care only about integrity
+		 * of the connection not performance.
+		 */
+		if (tp->rx_opt.sack_ok)
+			tcp_sack_reset(&tp->rx_opt);
+	}
+	return pruned;
 }
 
 /* Reduce allocated memory if we can, trying to get
@@ -5381,7 +5392,7 @@ static bool tcp_prune_ofo_queue(struct sock *sk)
  * until the socket owning process reads some of the data
  * to stabilize the situation.
  */
-static int tcp_prune_queue(struct sock *sk)
+static int tcp_prune_queue(struct sock *sk, const struct sk_buff *in_skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
@@ -5408,7 +5419,7 @@ static int tcp_prune_queue(struct sock *sk)
 	/* Collapsing did not help, destructive actions follow.
 	 * This must not ever occur. */
 
-	tcp_prune_ofo_queue(sk);
+	tcp_prune_ofo_queue(sk, in_skb);
 
 	if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf)
 		return 0;
@@ -6830,10 +6841,18 @@ static bool tcp_syn_flood_action(const struct sock *sk, const char *proto)
 #endif
 		__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPREQQFULLDROP);
 
-	if (!queue->synflood_warned && syncookies != 2 &&
-	    xchg(&queue->synflood_warned, 1) == 0)
-		net_info_ratelimited("%s: Possible SYN flooding on port %d. %s.  Check SNMP counters.\n",
-				     proto, sk->sk_num, msg);
+	if (!READ_ONCE(queue->synflood_warned) && syncookies != 2 &&
+	    xchg(&queue->synflood_warned, 1) == 0) {
+		if (IS_ENABLED(CONFIG_IPV6) && sk->sk_family == AF_INET6) {
+			net_info_ratelimited("%s: Possible SYN flooding on port [%pI6c]:%u. %s.\n",
+					proto, inet6_rcv_saddr(sk),
+					sk->sk_num, msg);
+		} else {
+			net_info_ratelimited("%s: Possible SYN flooding on port %pI4:%u. %s.\n",
+					proto, &sk->sk_rcv_saddr,
+					sk->sk_num, msg);
+		}
+	}
 
 	return want_cookie;
 }