[PATCH] Revert "ip_gre: make ipgre_tunnel_xmit() not parse network header as IP unconditionally"

["Timo Teräs" <timo.teras@iki.fi>]

This reverts commit 412ed94744d16806fbec3bd250fd94e71cde5a1f.

The commit is wrong as tiph points to the outer IPv4 header which is
installed at ipgre_header() and not the inner one which is protocol dependant.

This commit broke succesfully opennhrp which use PF_PACKET socket with
ETH_P_NHRP protocol. Additionally ssl_addr is set to the link-layer
IPv4 address. This address is written by ipgre_header() to the skb
earlier, and this is the IPv4 header tiph should point to - regardless
of the inner protocol payload.

Signed-off-by: Timo Teräs <timo.teras@iki.fi>
---
 net/ipv4/ip_gre.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)
 
This commit appeared in 3.8.x. So should go to 3.8.x-stable.

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index d0ef0e6..91d66db 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -798,10 +798,7 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
 
 	if (dev->header_ops && dev->type == ARPHRD_IPGRE) {
 		gre_hlen = 0;
-		if (skb->protocol == htons(ETH_P_IP))
-			tiph = (const struct iphdr *)skb->data;
-		else
-			tiph = &tunnel->parms.iph;
+		tiph = (const struct iphdr *)skb->data;
 	} else {
 		gre_hlen = tunnel->hlen;
 		tiph = &tunnel->parms.iph;
-- 
1.8.1.5