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/ipv6/icmp.c b/net/ipv6/icmp.c
index a77b8d1..4f43384 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -427,7 +427,7 @@
 	/* No need to clone since we're just using its address. */
 	dst2 = dst;
 
-	err = xfrm_lookup(&dst, &fl, sk, 0);
+	err = xfrm_lookup(net, &dst, &fl, sk, 0);
 	switch (err) {
 	case 0:
 		if (dst != dst2)
@@ -446,7 +446,7 @@
 	if (ip6_dst_lookup(sk, &dst2, &fl))
 		goto relookup_failed;
 
-	err = xfrm_lookup(&dst2, &fl, sk, XFRM_LOOKUP_ICMP);
+	err = xfrm_lookup(net, &dst2, &fl, sk, XFRM_LOOKUP_ICMP);
 	switch (err) {
 	case 0:
 		dst_release(dst);
@@ -552,7 +552,7 @@
 	err = ip6_dst_lookup(sk, &dst, &fl);
 	if (err)
 		goto out;
-	if ((err = xfrm_lookup(&dst, &fl, sk, 0)) < 0)
+	if ((err = xfrm_lookup(net, &dst, &fl, sk, 0)) < 0)
 		goto out;
 
 	if (ipv6_addr_is_multicast(&fl.fl6_dst))