net: gre: use icmp_hdr() to get inner ip header
When dealing with icmp messages, the skb->data points the
ip header that triggered the sending of the icmp message.
In gre_cisco_err(), the parse_gre_header() is called, and the
iptunnel_pull_header() is called to pull the skb at the end of
the parse_gre_header(), so the skb->data doesn't point the
inner ip header.
Unfortunately, the ipgre_err still needs those ip addresses in
inner ip header to look up tunnel by ip_tunnel_lookup().
So just use icmp_hdr() to get inner ip header instead of skb->data.
Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index e7a92fd..ec4f762 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -178,7 +178,7 @@
else
itn = net_generic(net, ipgre_net_id);
- iph = (const struct iphdr *)skb->data;
+ iph = (const struct iphdr *)(icmp_hdr(skb) + 1);
t = ip_tunnel_lookup(itn, skb->dev->ifindex, tpi->flags,
iph->daddr, iph->saddr, tpi->key);