Commit ba9e04a7 authored Sep 08, 2020 by Wei Wang Committed by David S. Miller Sep 08, 2020

ip: fix tos reflection in ack and reset packets



Currently, in tcp_v4_reqsk_send_ack() and tcp_v4_send_reset(), we
echo the TOS value of the received packets in the response.
However, we do not want to echo the lower 2 ECN bits in accordance
with RFC 3168 6.1.5 robustness principles.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")

Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 6fd40d32

net/ipv4/ip_output.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -74,6 +74,7 @@
		#include <net/icmp.h>
		#include <net/checksum.h>
		#include <net/inetpeer.h>
		#include <net/inet_ecn.h>
		#include <net/lwtunnel.h>
		#include <linux/bpf-cgroup.h>
		#include <linux/igmp.h>
		@@ -1703,7 +1704,7 @@ void ip_send_unicast_reply(struct sock sk, struct sk_buff skb,
		if (IS_ERR(rt))
		return;

		inet_sk(sk)->tos = arg->tos;
		inet_sk(sk)->tos = arg->tos & ~INET_ECN_MASK;

		sk->sk_protocol = ip_hdr(skb)->protocol;
		sk->sk_bound_dev_if = arg->bound_dev_if;

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