Merge branch 'gre-lwt-fixes'

Jiri Benc says:

====================
gre: fix lwtunnel support

This patchset fixes a few bugs in ipgre metadata mode implementation.

As an example, in this setup:

ip a a 192.168.1.1/24 dev eth0
ip l a gre1 type gre external
ip l s gre1 up
ip a a 192.168.99.1/24 dev gre1
ip r a 192.168.99.2/32 encap ip dst 192.168.1.2 ttl 10 dev gre1
ping 192.168.99.2

the traffic does not go through before this patchset and does as expected
with it applied.

v3: Back to v1 in order not to break existing users. Dropped patch 3, will
    be fixed in iproute2 instead.
v2: Rejecting invalid configuration, added patch 3, dropped patch for
    ETH_P_TEB (will target net-next).
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ip_gre.c

@@ -523,7 +523,8 @@ static struct rtable *gre_get_rt(struct sk_buff *skb,
 	return ip_route_output_key(net, fl);
 }
 
-static void gre_fb_xmit(struct sk_buff *skb, struct net_device *dev)
+static void gre_fb_xmit(struct sk_buff *skb, struct net_device *dev,
+			__be16 proto)
 {
 	struct ip_tunnel_info *tun_info;
 	const struct ip_tunnel_key *key;
@@ -575,7 +576,7 @@ static void gre_fb_xmit(struct sk_buff *skb, struct net_device *dev)
 	}
 
 	flags = tun_info->key.tun_flags & (TUNNEL_CSUM | TUNNEL_KEY);
-	build_header(skb, tunnel_hlen, flags, htons(ETH_P_TEB),
+	build_header(skb, tunnel_hlen, flags, proto,
 		     tunnel_id_to_key(tun_info->key.tun_id), 0);
 
 	df = key->tun_flags & TUNNEL_DONT_FRAGMENT ?  htons(IP_DF) : 0;
@@ -616,7 +617,7 @@ static netdev_tx_t ipgre_xmit(struct sk_buff *skb,
 	const struct iphdr *tnl_params;
 
 	if (tunnel->collect_md) {
-		gre_fb_xmit(skb, dev);
+		gre_fb_xmit(skb, dev, skb->protocol);
 		return NETDEV_TX_OK;
 	}
 
@@ -660,7 +661,7 @@ static netdev_tx_t gre_tap_xmit(struct sk_buff *skb,
 	struct ip_tunnel *tunnel = netdev_priv(dev);
 
 	if (tunnel->collect_md) {
-		gre_fb_xmit(skb, dev);
+		gre_fb_xmit(skb, dev, htons(ETH_P_TEB));
 		return NETDEV_TX_OK;
 	}
 
@@ -893,7 +894,7 @@ static int ipgre_tunnel_init(struct net_device *dev)
 	netif_keep_dst(dev);
 	dev->addr_len		= 4;
 
-	if (iph->daddr) {
+	if (iph->daddr && !tunnel->collect_md) {
 #ifdef CONFIG_NET_IPGRE_BROADCAST
 		if (ipv4_is_multicast(iph->daddr)) {
 			if (!iph->saddr)
@@ -902,8 +903,9 @@ static int ipgre_tunnel_init(struct net_device *dev)
 			dev->header_ops = &ipgre_header_ops;
 		}
 #endif
-	} else
+	} else if (!tunnel->collect_md) {
 		dev->header_ops = &ipgre_header_ops;
+	}
 
 	return ip_tunnel_init(dev);
 }