dev: introduce skb_scrub_packet()

The goal of this new function is to perform all needed cleanup before sending
an skb into another netns.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index 722f633..370354a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1652,22 +1652,13 @@
 		}
 	}
 
-	skb_orphan(skb);
-
 	if (unlikely(!is_skb_forwardable(dev, skb))) {
 		atomic_long_inc(&dev->rx_dropped);
 		kfree_skb(skb);
 		return NET_RX_DROP;
 	}
-	skb->skb_iif = 0;
-	skb_dst_drop(skb);
-	skb->tstamp.tv64 = 0;
-	skb->pkt_type = PACKET_HOST;
+	skb_scrub_packet(skb);
 	skb->protocol = eth_type_trans(skb, dev);
-	skb->mark = 0;
-	secpath_reset(skb);
-	nf_reset(skb);
-	nf_reset_trace(skb);
 	return netif_rx(skb);
 }
 EXPORT_SYMBOL_GPL(dev_forward_skb);