ip_gre: make ipgre_tunnel_xmit() not parse network header as IP unconditionally

ipgre_tunnel_xmit() parses network header as IP unconditionally.
But transmitting packets are not always IP packet. For example such packet
can be sent by packet socket with sockaddr_ll.sll_protocol set.
So make the function check if skb->protocol is IP.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Acked-by: Eric Dumazet <edumazet@google.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 a85ae2f7a21cb15502bd69e9c63a1ec29020fa40..8fcf0ed76548a31074293d26a671fbbd9a32845e 100644 (file)
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -760,7 +760,10 @@ 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;
-               tiph = (const struct iphdr *)skb->data;
+               if (skb->protocol == htons(ETH_P_IP))
+                       tiph = (const struct iphdr *)skb->data;
+               else
+                       tiph = &tunnel->parms.iph;
        } else {
                gre_hlen = tunnel->hlen;
                tiph = &tunnel->parms.iph;