From 0b922b7a829c06e3b0790c58cd9ca026de86096e Mon Sep 17 00:00:00 2001
From: David Ahern <dsa@cumulusnetworks.com>
Date: Tue, 10 May 2016 11:19:51 -0700
Subject: [PATCH] net: original ingress device index in PKTINFO
Applications such as OSPF and BFD need the original ingress device not
the VRF device; the latter can be derived from the former. To that end
add the skb_iif to inet_skb_parm and set it in ipv4 code after clearing
the skb control buffer similar to IPv6. From there the pktinfo can just
pull it from cb with the PKTINFO_SKB_CB cast.
The previous patch moving the skb->dev change to L3 means nothing else
is needed for IPv6; it just works.
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/net/ip.h | 1 +
net/ipv4/ip_input.c | 1 +
net/ipv4/ip_sockglue.c | 7 ++++++-
3 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/include/net/ip.h b/include/net/ip.h
index 247ac82e9cf26..37165fba3741a 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -36,6 +36,7 @@
struct sock;
struct inet_skb_parm {
+ int iif;
struct ip_options opt; /* Compiled IP options */
unsigned char flags;
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 37375eedeef92..4b351af3e67b6 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -478,6 +478,7 @@ int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt,
/* Remove any debris in the socket control block */
memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
+ IPCB(skb)->iif = skb->skb_iif;
/* Must drop socket now because of tproxy. */
skb_orphan(skb);
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index bdb222c0c6a21..5805762d7fc79 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -1193,7 +1193,12 @@ void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb)
ipv6_sk_rxinfo(sk);
if (prepare && skb_rtable(skb)) {
- pktinfo->ipi_ifindex = inet_iif(skb);
+ /* skb->cb is overloaded: prior to this point it is IP{6}CB
+ * which has interface index (iif) as the first member of the
+ * underlying inet{6}_skb_parm struct. This code then overlays
+ * PKTINFO_SKB_CB and in_pktinfo also has iif as the first
+ * element so the iif is picked up from the prior IPCB
+ */
pktinfo->ipi_spec_dst.s_addr = fib_compute_spec_dst(skb);
} else {
pktinfo->ipi_ifindex = 0;
--
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