From cbea8f02069533ea2ad4e5b3bfbcdb0894c20354 Mon Sep 17 00:00:00 2001
From: David Ahern <dsahern@gmail.com>
Date: Wed, 13 Sep 2017 17:11:37 -0700
Subject: [PATCH] net: ipv4: fix l3slave check for index returned in IP_PKTINFO
rt_iif is only set to the actual egress device for the output path. The
recent change to consider the l3slave flag when returning IP_PKTINFO
works for local traffic (the correct device index is returned), but it
broke the more typical use case of packets received from a remote host
always returning the VRF index rather than the original ingress device.
Update the fixup to consider l3slave and rt_iif actually getting set.
Fixes: 1dfa76390bf05 ("net: ipv4: add check for l3slave for index returned in IP_PKTINFO")
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/ip_sockglue.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index e558e4f9597b5..a599aa83fdadf 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -1207,7 +1207,6 @@ static int do_ip_setsockopt(struct sock *sk, int level,
void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb)
{
struct in_pktinfo *pktinfo = PKTINFO_SKB_CB(skb);
- bool l3slave = ipv4_l3mdev_skb(IPCB(skb)->flags);
bool prepare = (inet_sk(sk)->cmsg_flags & IP_CMSG_PKTINFO) ||
ipv6_sk_rxinfo(sk);
@@ -1221,8 +1220,13 @@ void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb)
* (e.g., process binds socket to eth0 for Tx which is
* redirected to loopback in the rtable/dst).
*/
- if (pktinfo->ipi_ifindex == LOOPBACK_IFINDEX || l3slave)
+ struct rtable *rt = skb_rtable(skb);
+ bool l3slave = ipv4_l3mdev_skb(IPCB(skb)->flags);
+
+ if (pktinfo->ipi_ifindex == LOOPBACK_IFINDEX)
pktinfo->ipi_ifindex = inet_iif(skb);
+ else if (l3slave && rt && rt->rt_iif)
+ pktinfo->ipi_ifindex = rt->rt_iif;
pktinfo->ipi_spec_dst.s_addr = fib_compute_spec_dst(skb);
} else {
--
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