netfilter: conntrack: make netns address part of hash

Once we place all conntracks into a global hash table we want them to be
spread across entire hash table, even if namespaces have overlapping ip
addresses.

Signed-off-by: Florian Westphal <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

net/netfilter/nf_conntrack_core.c

···
 #include <net/netfilter/nf_nat.h>
 #include <net/netfilter/nf_nat_core.h>
 #include <net/netfilter/nf_nat_helper.h>
+#include <net/netns/hash.h>
 
 #define NF_CONNTRACK_VERSION	"0.5.0"
 
···
 
 static unsigned int nf_conntrack_hash_rnd __read_mostly;
 
-static u32 hash_conntrack_raw(const struct nf_conntrack_tuple *tuple)
+static u32 hash_conntrack_raw(const struct nf_conntrack_tuple *tuple,
+			      const struct net *net)
 {
 	unsigned int n;
+	u32 seed;
 
 	get_random_once(&nf_conntrack_hash_rnd, sizeof(nf_conntrack_hash_rnd));
 
···
 	 * destination ports (which is a multiple of 4) and treat the last
 	 * three bytes manually.
 	 */
+	seed = nf_conntrack_hash_rnd ^ net_hash_mix(net);
 	n = (sizeof(tuple->src) + sizeof(tuple->dst.u3)) / sizeof(u32);
-	return jhash2((u32 *)tuple, n, nf_conntrack_hash_rnd ^
+	return jhash2((u32 *)tuple, n, seed ^
 		      (((__force __u16)tuple->dst.u.all << 16) |
 		      tuple->dst.protonum));
 }
 
-static u32 __hash_bucket(u32 hash, unsigned int size)
-{
-	return reciprocal_scale(hash, size);
-}
-
 static u32 hash_bucket(u32 hash, const struct net *net)
 {
-	return __hash_bucket(hash, net->ct.htable_size);
+	return reciprocal_scale(hash, net->ct.htable_size);
 }
 
-static u_int32_t __hash_conntrack(const struct nf_conntrack_tuple *tuple,
-				  unsigned int size)
+static u32 __hash_conntrack(const struct net *net,
+			    const struct nf_conntrack_tuple *tuple,
+			    unsigned int size)
 {
-	return __hash_bucket(hash_conntrack_raw(tuple), size);
+	return reciprocal_scale(hash_conntrack_raw(tuple, net), size);
 }
 
-static inline u_int32_t hash_conntrack(const struct net *net,
-				       const struct nf_conntrack_tuple *tuple)
+static u32 hash_conntrack(const struct net *net,
+			  const struct nf_conntrack_tuple *tuple)
 {
-	return __hash_conntrack(tuple, net->ct.htable_size);
+	return __hash_conntrack(net, tuple, net->ct.htable_size);
 }
 
 bool
···
 		      const struct nf_conntrack_tuple *tuple)
 {
 	return __nf_conntrack_find_get(net, zone, tuple,
-				       hash_conntrack_raw(tuple));
+				       hash_conntrack_raw(tuple, net));
 }
 EXPORT_SYMBOL_GPL(nf_conntrack_find_get);
 
···
 
 	/* look for tuple match */
 	zone = nf_ct_zone_tmpl(tmpl, skb, &tmp);
-	hash = hash_conntrack_raw(&tuple);
+	hash = hash_conntrack_raw(&tuple, net);
 	h = __nf_conntrack_find_get(net, zone, &tuple, hash);
 	if (!h) {
 		h = init_conntrack(net, tmpl, &tuple, l3proto, l4proto,
···
 					struct nf_conntrack_tuple_hash, hnnode);
 			ct = nf_ct_tuplehash_to_ctrack(h);
 			hlist_nulls_del_rcu(&h->hnnode);
-			bucket = __hash_conntrack(&h->tuple, hashsize);
+			bucket = __hash_conntrack(nf_ct_net(ct),
+						  &h->tuple, hashsize);
 			hlist_nulls_add_head_rcu(&h->hnnode, &hash[bucket]);
 		}
 	}