netdev - [PATCH net-next] tcp: md5: increment sk_drops on syn

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Message-ID: <1472053824.14381.82.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Wed, 24 Aug 2016 08:50:24 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Neal Cardwell <ncardwell@...gle.com>,
        Yuchung Cheng <ycheng@...gle.com>,
        Julien Goodwin <julieng@...gle.com>
Subject: [PATCH net-next] tcp: md5: increment sk_drops on syn_recv state

From: Eric Dumazet <edumazet@...gle.com>

TCP MD5 mismatches do increment sk_drops counter in all states but
SYN_RECV.

This is very unlikely to happen in the real world, but worth adding
to help diagnostics.

We increase the parent (listener) sk_drops.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/tcp_ipv4.c |    1 +
 net/ipv6/tcp_ipv6.c |    1 +
 2 files changed, 2 insertions(+)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 32b048e524d6773538918eca175b3f422f9c2aa7..436d978c6c3955dfa9a55f86b1412624ba2ed9fa 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1602,6 +1602,7 @@ process:
 
 		sk = req->rsk_listener;
 		if (unlikely(tcp_v4_inbound_md5_hash(sk, skb))) {
+			sk_drops_add(sk, skb);
 			reqsk_put(req);
 			goto discard_it;
 		}
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index e0f46439e391f2a8b2fac2e13b6f61a11c082715..ac0ed7bda4067a2630cc1cbb546ced3f3ded4c2c 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1409,6 +1409,7 @@ process:
 		sk = req->rsk_listener;
 		tcp_v6_fill_cb(skb, hdr, th);
 		if (tcp_v6_inbound_md5_hash(sk, skb)) {
+			sk_drops_add(sk, skb);
 			reqsk_put(req);
 			goto discard_it;
 		}