ipvlan: scrub skb before routing in L3 mode.

Scrub skb before hitting the iptable hooks to ensure packets hit
these hooks. Set the xnet param only when the packet is crossing the
ns boundry so if the IPvlan slave and master belong to the same ns,
the param will be set to false.

Signed-off-by: Mahesh Bandewar <maheshb@google.com>
CC: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: Mahesh Bandewar

drivers/net/ipvlan/ipvlan_core.c

@@ -342,7 +342,7 @@ static struct ipvl_addr *ipvlan_addr_lookup(struct ipvl_port *port,
 	return addr;
 }
 
-static int ipvlan_process_v4_outbound(struct sk_buff *skb)
+static int ipvlan_process_v4_outbound(struct sk_buff *skb, bool xnet)
 {
 	const struct iphdr *ip4h = ip_hdr(skb);
 	struct net_device *dev = skb->dev;
@@ -365,7 +365,7 @@ static int ipvlan_process_v4_outbound(struct sk_buff *skb)
 		ip_rt_put(rt);
 		goto err;
 	}
-	skb_dst_drop(skb);
+	skb_scrub_packet(skb, xnet);
 	skb_dst_set(skb, &rt->dst);
 	err = ip_local_out(net, skb->sk, skb);
 	if (unlikely(net_xmit_eval(err)))
@@ -380,7 +380,7 @@ static int ipvlan_process_v4_outbound(struct sk_buff *skb)
 	return ret;
 }
 
-static int ipvlan_process_v6_outbound(struct sk_buff *skb)
+static int ipvlan_process_v6_outbound(struct sk_buff *skb, bool xnet)
 {
 	const struct ipv6hdr *ip6h = ipv6_hdr(skb);
 	struct net_device *dev = skb->dev;
@@ -403,7 +403,7 @@ static int ipvlan_process_v6_outbound(struct sk_buff *skb)
 		dst_release(dst);
 		goto err;
 	}
-	skb_dst_drop(skb);
+	skb_scrub_packet(skb, xnet);
 	skb_dst_set(skb, dst);
 	err = ip6_local_out(net, skb->sk, skb);
 	if (unlikely(net_xmit_eval(err)))
@@ -418,8 +418,7 @@ static int ipvlan_process_v6_outbound(struct sk_buff *skb)
 	return ret;
 }
 
-static int ipvlan_process_outbound(struct sk_buff *skb,
-				   const struct ipvl_dev *ipvlan)
+static int ipvlan_process_outbound(struct sk_buff *skb, bool xnet)
 {
 	struct ethhdr *ethh = eth_hdr(skb);
 	int ret = NET_XMIT_DROP;
@@ -443,9 +442,9 @@ static int ipvlan_process_outbound(struct sk_buff *skb,
 	}
 
 	if (skb->protocol == htons(ETH_P_IPV6))
-		ret = ipvlan_process_v6_outbound(skb);
+		ret = ipvlan_process_v6_outbound(skb, xnet);
 	else if (skb->protocol == htons(ETH_P_IP))
-		ret = ipvlan_process_v4_outbound(skb);
+		ret = ipvlan_process_v4_outbound(skb, xnet);
 	else {
 		pr_warn_ratelimited("Dropped outbound packet type=%x\n",
 				    ntohs(skb->protocol));
@@ -481,6 +480,7 @@ static int ipvlan_xmit_mode_l3(struct sk_buff *skb, struct net_device *dev)
 	void *lyr3h;
 	struct ipvl_addr *addr;
 	int addr_type;
+	bool xnet;
 
 	lyr3h = ipvlan_get_L3_hdr(skb, &addr_type);
 	if (!lyr3h)
@@ -491,8 +491,9 @@ static int ipvlan_xmit_mode_l3(struct sk_buff *skb, struct net_device *dev)
 		return ipvlan_rcv_frame(addr, &skb, true);
 
 out:
+	xnet = !net_eq(dev_net(skb->dev), dev_net(ipvlan->phy_dev));
 	skb->dev = ipvlan->phy_dev;
-	return ipvlan_process_outbound(skb, ipvlan);
+	return ipvlan_process_outbound(skb, xnet);
 }
 
 static int ipvlan_xmit_mode_l2(struct sk_buff *skb, struct net_device *dev)