[PATCH v2] ip_tunnel: Make none-tunnel-dst tunnel port work with lwtunnel

[wenxu]

From: wenxu <we...@ucloud.cn>

ip l add dev tun type gretap key 1000
ip a a dev tun 10.0.0.1/24

Packets with tun-id 1000 can be recived by tun dev. But packet can't
be sent through dev tun for non-tunnel-dst

With this patch: tunnel-dst can be get through lwtunnel like beflow:
ip r a 10.0.0.7 encap ip dst 172.168.0.11 dev tun

Signed-off-by: wenxu <we...@ucloud.cn>
---
 net/ipv4/ip_tunnel.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index c4f5602..09abc23 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -644,13 +644,19 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct 
net_device *dev,
        dst = tnl_params->daddr;
        if (dst == 0) {
                /* NBMA tunnel */
+               struct ip_tunnel_info *tun_info;
 
                if (!skb_dst(skb)) {
                        dev->stats.tx_fifo_errors++;
                        goto tx_error;
                }
 
-               if (skb->protocol == htons(ETH_P_IP)) {
+               tun_info = skb_tunnel_info(skb);
+               if (tun_info && (tun_info->mode & IP_TUNNEL_INFO_TX) &&
+                   ip_tunnel_info_af(tun_info) == AF_INET &&
+                   tun_info->key.u.ipv4.dst)
+                       dst = tun_info->key.u.ipv4.dst;
+               else if (skb->protocol == htons(ETH_P_IP)) {
                        rt = skb_rtable(skb);
                        dst = rt_nexthop(rt, inner_iph->daddr);
                }
-- 
1.8.3.1