ip_tunnel: Add tnl_update_pmtu in ip_md_tunnel_xmit

Add tnl_update_pmtu in ip_md_tunnel_xmit to dynamic modify
the pmtu which packet send through collect_metadata mode
ip tunnel
Signed-off-by: wenxu <wenxu@ucloud.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip_tunnels.h

@@ -267,7 +267,7 @@ void ip_tunnel_delete_nets(struct list_head *list_net, unsigned int id,
 void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 		    const struct iphdr *tnl_params, const u8 protocol);
 void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
-		       const u8 proto);
+		       const u8 proto, int tunnel_hlen);
 int ip_tunnel_ioctl(struct net_device *dev, struct ip_tunnel_parm *p, int cmd);
 int __ip_tunnel_change_mtu(struct net_device *dev, int new_mtu, bool strict);
 int ip_tunnel_change_mtu(struct net_device *dev, int new_mtu);

net/ipv4/ip_tunnel.c

@@ -501,15 +501,19 @@ EXPORT_SYMBOL_GPL(ip_tunnel_encap_setup);
 
 static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,
 			    struct rtable *rt, __be16 df,
-			    const struct iphdr *inner_iph)
+			    const struct iphdr *inner_iph,
+			    int tunnel_hlen, __be32 dst, bool md)
 {
 	struct ip_tunnel *tunnel = netdev_priv(dev);
-	int pkt_size = skb->len - tunnel->hlen - dev->hard_header_len;
+	int pkt_size;
 	int mtu;
 
+	tunnel_hlen = md ? tunnel_hlen : tunnel->hlen;
+	pkt_size = skb->len - tunnel_hlen - dev->hard_header_len;
+
 	if (df)
 		mtu = dst_mtu(&rt->dst) - dev->hard_header_len
-					- sizeof(struct iphdr) - tunnel->hlen;
+					- sizeof(struct iphdr) - tunnel_hlen;
 	else
 		mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;
 
@@ -527,11 +531,13 @@ static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,
 #if IS_ENABLED(CONFIG_IPV6)
 	else if (skb->protocol == htons(ETH_P_IPV6)) {
 		struct rt6_info *rt6 = (struct rt6_info *)skb_dst(skb);
+		__be32 daddr;
+
+		daddr = md ? dst : tunnel->parms.iph.daddr;
 
 		if (rt6 && mtu < dst_mtu(skb_dst(skb)) &&
 			   mtu >= IPV6_MIN_MTU) {
-			if ((tunnel->parms.iph.daddr &&
-			    !ipv4_is_multicast(tunnel->parms.iph.daddr)) ||
+			if ((daddr && !ipv4_is_multicast(daddr)) ||
 			    rt6->rt6i_dst.plen == 128) {
 				rt6->rt6i_flags |= RTF_MODIFIED;
 				dst_metric_set(skb_dst(skb), RTAX_MTU, mtu);
@@ -548,7 +554,8 @@ static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,
 	return 0;
 }
 
-void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, u8 proto)
+void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
+		       u8 proto, int tunnel_hlen)
 {
 	struct ip_tunnel *tunnel = netdev_priv(dev);
 	u32 headroom = sizeof(struct iphdr);
@@ -598,6 +605,15 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, u8 proto)
 		dev->stats.collisions++;
 		goto tx_error;
 	}
+
+	if (key->tun_flags & TUNNEL_DONT_FRAGMENT)
+		df = htons(IP_DF);
+	if (tnl_update_pmtu(dev, skb, rt, df, inner_iph, tunnel_hlen,
+			    key->u.ipv4.dst, true)) {
+		ip_rt_put(rt);
+		goto tx_error;
+	}
+
 	tos = ip_tunnel_ecn_encap(tos, inner_iph, skb);
 	ttl = key->ttl;
 	if (ttl == 0) {
@@ -608,10 +624,10 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, u8 proto)
 		else
 			ttl = ip4_dst_hoplimit(&rt->dst);
 	}
-	if (key->tun_flags & TUNNEL_DONT_FRAGMENT)
-		df = htons(IP_DF);
-	else if (skb->protocol == htons(ETH_P_IP))
+
+	if (!df && skb->protocol == htons(ETH_P_IP))
 		df = inner_iph->frag_off & htons(IP_DF);
+
 	headroom += LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len;
 	if (headroom > dev->needed_headroom)
 		dev->needed_headroom = headroom;
@@ -741,7 +757,8 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 		goto tx_error;
 	}
 
-	if (tnl_update_pmtu(dev, skb, rt, tnl_params->frag_off, inner_iph)) {
+	if (tnl_update_pmtu(dev, skb, rt, tnl_params->frag_off, inner_iph,
+			    0, 0, false)) {
 		ip_rt_put(rt);
 		goto tx_error;
 	}

net/ipv4/ipip.c

@@ -302,7 +302,7 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb,
 	skb_set_inner_ipproto(skb, ipproto);
 
 	if (tunnel->collect_md)
-		ip_md_tunnel_xmit(skb, dev, ipproto);
+		ip_md_tunnel_xmit(skb, dev, ipproto, 0);
 	else
 		ip_tunnel_xmit(skb, dev, tiph, ipproto);
 	return NETDEV_TX_OK;