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From ebf148a0ca2e0c9fb824a069c0fd5311bb6ae297 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 2 Dec 2011 23:41:42 +0000
Subject: [PATCH 003/109] tcp: drop SYN+FIN messages
commit fdf5af0daf8019cec2396cdef8fb042d80fe71fa upstream.
Denys Fedoryshchenko reported that SYN+FIN attacks were bringing his
linux machines to their limits.
Dont call conn_request() if the TCP flags includes SYN flag
Reported-by: Denys Fedoryshchenko <denys@visp.net.lb>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/ipv4/tcp_input.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 9726927..32e6ca2 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5836,6 +5836,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
goto discard;
if (th->syn) {
+ if (th->fin)
+ goto discard;
if (icsk->icsk_af_ops->conn_request(sk, skb) < 0)
return 1;
--
1.7.7.6
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