From 87cdf3148b11d46382dbce2754ae7036aba96380 Mon Sep 17 00:00:00 2001
From: Yossi Kuperman <yossiku@mellanox.com>
Date: Sun, 4 Mar 2018 21:03:52 +0200
Subject: [PATCH] xfrm: Verify MAC header exists before overwriting
eth_hdr(skb)->h_proto
Artem Savkov reported that commit 5efec5c655dd leads to a packet loss under
IPSec configuration. It appears that his setup consists of a TUN device,
which does not have a MAC header.
Make sure MAC header exists.
Note: TUN device sets a MAC header pointer, although it does not have one.
Fixes: 5efec5c655dd ("xfrm: Fix eth_hdr(skb)->h_proto to reflect inner IP version")
Reported-by: Artem Savkov <artem.savkov@gmail.com>
Tested-by: Artem Savkov <artem.savkov@gmail.com>
Signed-off-by: Yossi Kuperman <yossiku@mellanox.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
net/ipv4/xfrm4_mode_tunnel.c | 3 ++-
net/ipv6/xfrm6_mode_tunnel.c | 3 ++-
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/xfrm4_mode_tunnel.c b/net/ipv4/xfrm4_mode_tunnel.c
index 63faeee989a9..2a9764bd1719 100644
--- a/net/ipv4/xfrm4_mode_tunnel.c
+++ b/net/ipv4/xfrm4_mode_tunnel.c
@@ -92,7 +92,8 @@ static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
skb_reset_network_header(skb);
skb_mac_header_rebuild(skb);
- eth_hdr(skb)->h_proto = skb->protocol;
+ if (skb->mac_len)
+ eth_hdr(skb)->h_proto = skb->protocol;
err = 0;
diff --git a/net/ipv6/xfrm6_mode_tunnel.c b/net/ipv6/xfrm6_mode_tunnel.c
index bb935a3b7fea..de1b0b8c53b0 100644
--- a/net/ipv6/xfrm6_mode_tunnel.c
+++ b/net/ipv6/xfrm6_mode_tunnel.c
@@ -92,7 +92,8 @@ static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
skb_reset_network_header(skb);
skb_mac_header_rebuild(skb);
- eth_hdr(skb)->h_proto = skb->protocol;
+ if (skb->mac_len)
+ eth_hdr(skb)->h_proto = skb->protocol;
err = 0;