netns xfrm: lookup in netns

Pass netns to xfrm_lookup()/__xfrm_lookup(). For that pass netns
to flow_cache_lookup() and resolver callback.

Take it from socket or netdevice. Stub DECnet to init_net.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 7b88be9..705b33b 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -562,7 +562,7 @@
 		/* No need to clone since we're just using its address. */
 		rt2 = rt;
 
-		err = xfrm_lookup((struct dst_entry **)&rt, &fl, NULL, 0);
+		err = xfrm_lookup(net, (struct dst_entry **)&rt, &fl, NULL, 0);
 		switch (err) {
 		case 0:
 			if (rt != rt2)
@@ -601,7 +601,7 @@
 		if (err)
 			goto relookup_failed;
 
-		err = xfrm_lookup((struct dst_entry **)&rt2, &fl, NULL,
+		err = xfrm_lookup(net, (struct dst_entry **)&rt2, &fl, NULL,
 				  XFRM_LOOKUP_ICMP);
 		switch (err) {
 		case 0: