Commit 9b6c14d5 authored Nov 09, 2016 by David Ahern Committed by David S. Miller Nov 09, 2016

net: tcp response should set oif only if it is L3 master



Lorenzo noted an Android unit test failed due to e0d56fdd:
"The expectation in the test was that the RST replying to a SYN sent to a
closed port should be generated with oif=0. In other words it should not
prefer the interface where the SYN came in on, but instead should follow
whatever the routing table says it should do."

Revert the change to ip_send_unicast_reply and tcp_v6_send_response such
that the oif in the flow is set to the skb_iif only if skb_iif is an L3
master.

Fixes: e0d56fdd ("net: l3mdev: remove redundant calls")
Reported-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Tested-by: Lorenzo Colitti <lorenzo@google.com>
Acked-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 8da3cf2a

net/ipv4/ip_output.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1577,7 +1577,8 @@ void ip_send_unicast_reply(struct sock sk, struct sk_buff skb,
		}

		oif = arg->bound_dev_if;
		oif = oif ? : skb->skb_iif;
		if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
		oif = skb->skb_iif;

		flowi4_init_output(&fl4, oif,
		IP4_REPLY_MARK(net, skb->mark),

net/ipv6/tcp_ipv6.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -818,8 +818,12 @@ static void tcp_v6_send_response(const struct sock sk, struct sk_buff skb, u32
		fl6.flowi6_proto = IPPROTO_TCP;
		if (rt6_need_strict(&fl6.daddr) && !oif)
		fl6.flowi6_oif = tcp_v6_iif(skb);
		else
		fl6.flowi6_oif = oif ? : skb->skb_iif;
		else {
		if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
		oif = skb->skb_iif;

		fl6.flowi6_oif = oif;
		}

		fl6.flowi6_mark = IP6_REPLY_MARK(net, skb->mark);
		fl6.fl6_dport = t1->dest;

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