From 87cdf3148b11d46382dbce2754ae7036aba96380 Mon Sep 17 00:00:00 2001 From: Yossi Kuperman 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 Tested-by: Artem Savkov Signed-off-by: Yossi Kuperman Signed-off-by: Steffen Klassert --- 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;