2018-01-22 22:18:08

by Yossi Kuperman

Subject: [PATCH net] xfrm: Fix eth_hdr(skb)->h_proto to reflect inner IP version

From: Yossi Kuperman <[email protected]>

IPSec tunnel mode supports encapsulation of IPv4 over IPv6 and vice-versa.

The outer IP header is stripped and the inner IP inherits the original
Ethernet header. Tcpdump fails to properly decode the inner packet in
case that h_proto is different than the inner IP version.

Fix h_proto to reflect the inner IP version.

Signed-off-by: Yossi Kuperman <[email protected]>
---
net/ipv4/xfrm4_mode_tunnel.c | 1 +
net/ipv6/xfrm6_mode_tunnel.c | 1 +
2 files changed, 2 insertions(+)

diff --git a/net/ipv4/xfrm4_mode_tunnel.c b/net/ipv4/xfrm4_mode_tunnel.c
index e6265e2..20ca486 100644
--- a/net/ipv4/xfrm4_mode_tunnel.c
+++ b/net/ipv4/xfrm4_mode_tunnel.c
@@ -92,6 +92,7 @@ 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;

err = 0;

diff --git a/net/ipv6/xfrm6_mode_tunnel.c b/net/ipv6/xfrm6_mode_tunnel.c
index 02556e3..dc93002 100644
--- a/net/ipv6/xfrm6_mode_tunnel.c
+++ b/net/ipv6/xfrm6_mode_tunnel.c
@@ -92,6 +92,7 @@ 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;

err = 0;

--
2.8.1

2018-01-24 06:12:44

by Steffen Klassert

Subject: Re: [PATCH net] xfrm: Fix eth_hdr(skb)->h_proto to reflect inner IP version

On Tue, Jan 23, 2018 at 12:16:21AM +0200, [email protected] wrote:
> From: Yossi Kuperman <[email protected]>
>
> IPSec tunnel mode supports encapsulation of IPv4 over IPv6 and vice-versa.
>
> The outer IP header is stripped and the inner IP inherits the original
> Ethernet header. Tcpdump fails to properly decode the inner packet in
> case that h_proto is different than the inner IP version.
>
> Fix h_proto to reflect the inner IP version.
>
> Signed-off-by: Yossi Kuperman <[email protected]>

Applied, thanks Yossi!