tcp: refine SYN handling in tcp_validate_incoming
authorEric Dumazet <edumazet@google.com>
Tue, 17 Jul 2012 12:29:30 +0000 (12:29 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 11 Jan 2013 17:07:15 +0000 (09:07 -0800)
commitf451931e294c83d811783799f8a6c29929fc8e85
tree2ea952d980f047320f2ad1358117dbb65877cc1d
parentd21383fcbb535f90b429279852988d675ed22d67
tcp: refine SYN handling in tcp_validate_incoming

[ Upstream commit e371589917011efe6ff8c7dfb4e9e81934ac5855 ]

Followup of commit 0c24604b68fc (tcp: implement RFC 5961 4.2)

As reported by Vijay Subramanian, we should send a challenge ACK
instead of a dup ack if a SYN flag is set on a packet received out of
window.

This permits the ratelimiting to work as intended, and to increase
correct SNMP counters.

Suggested-by: Vijay Subramanian <subramanian.vijay@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Vijay Subramanian <subramanian.vijay@gmail.com>
Cc: Kiran Kumar Kella <kkiran@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net/ipv4/tcp_input.c