From 9b6c14d51bd2304b92f842e96172a9cc822fc77c Mon Sep 17 00:00:00 2001 From: David Ahern Date: Wed, 9 Nov 2016 09:07:26 -0800 Subject: [PATCH] net: tcp response should set oif only if it is L3 master Lorenzo noted an Android unit test failed due to e0d56fdd7342: "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: e0d56fdd7342 ("net: l3mdev: remove redundant calls") Reported-by: Lorenzo Colitti Signed-off-by: David Ahern Tested-by: Lorenzo Colitti Acked-by: Lorenzo Colitti Signed-off-by: David S. Miller --- net/ipv4/ip_output.c | 3 ++- net/ipv6/tcp_ipv6.c | 8 ++++++-- 2 files changed, 8 insertions(+), 3 deletions(-) diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 49714010ac2e..9403fa3850be 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -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), diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 5a27ab4eab39..6ca23c2e76f7 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -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;