netdev - [bpf-next 1/6] tcp: tcp_syn_flood_action read port from socket

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Message-Id: <20190723002042.105927-2-ppenkov.kernel@gmail.com>
Date:   Mon, 22 Jul 2019 17:20:37 -0700
From:   Petar Penkov <ppenkov.kernel@...il.com>
To:     netdev@...r.kernel.org, bpf@...r.kernel.org
Cc:     davem@...emloft.net, ast@...nel.org, daniel@...earbox.net,
        edumazet@...gle.com, lmb@...udflare.com, sdf@...gle.com,
        Petar Penkov <ppenkov@...gle.com>
Subject: [bpf-next 1/6] tcp: tcp_syn_flood_action read port from socket

From: Petar Penkov <ppenkov@...gle.com>

This allows us to call this function before an SKB has been
allocated.

Signed-off-by: Petar Penkov <ppenkov@...gle.com>
---
 net/ipv4/tcp_input.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index c21e8a22fb3b..8892df6de1d4 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6422,9 +6422,7 @@ EXPORT_SYMBOL(inet_reqsk_alloc);
 /*
  * Return true if a syncookie should be sent
  */
-static bool tcp_syn_flood_action(const struct sock *sk,
-				 const struct sk_buff *skb,
-				 const char *proto)
+static bool tcp_syn_flood_action(const struct sock *sk, const char *proto)
 {
 	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
 	const char *msg = "Dropping request";
@@ -6444,7 +6442,7 @@ static bool tcp_syn_flood_action(const struct sock *sk,
 	    net->ipv4.sysctl_tcp_syncookies != 2 &&
 	    xchg(&queue->synflood_warned, 1) == 0)
 		net_info_ratelimited("%s: Possible SYN flooding on port %d. %s.  Check SNMP counters.\n",
-				     proto, ntohs(tcp_hdr(skb)->dest), msg);
+				     proto, sk->sk_num, msg);
 
 	return want_cookie;
 }
@@ -6487,7 +6485,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 	 */
 	if ((net->ipv4.sysctl_tcp_syncookies == 2 ||
 	     inet_csk_reqsk_queue_is_full(sk)) && !isn) {
-		want_cookie = tcp_syn_flood_action(sk, skb, rsk_ops->slab_name);
+		want_cookie = tcp_syn_flood_action(sk, rsk_ops->slab_name);
 		if (!want_cookie)
 			goto drop;
 	}
-- 
2.22.0.657.g960e92d24f-goog