ipv6: Use universal hash for NDISC.

In order to perform a proper universal hash on a vector of integers,
we have to use different universal hashes on each vector element.

Which means we need 4 different hash randoms for ipv6.

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 14 insertions, 3 deletions

diff --git a/include/net/arp.h b/include/net/arp.h
index 4979af8b..0013dc8 100644
--- a/include/net/arp.h
+++ b/include/net/arp.h
@@ -23,7 +23,7 @@ static inline struct neighbour *__ipv4_neigh_lookup(struct neigh_table *tbl, str
 
 	rcu_read_lock_bh();
 	nht = rcu_dereference_bh(tbl->nht);
-	hash_val = arp_hashfn(key, dev, nht->hash_rnd) >> (32 - nht->hash_shift);
+	hash_val = arp_hashfn(key, dev, nht->hash_rnd[0]) >> (32 - nht->hash_shift);
 	for (n = rcu_dereference_bh(nht->hash_buckets[hash_val]);
 	     n != NULL;
 	     n = rcu_dereference_bh(n->next)) {
diff --git a/include/net/ndisc.h b/include/net/ndisc.h
index c977c37..e9c3002 100644
--- a/include/net/ndisc.h
+++ b/include/net/ndisc.h
@@ -79,6 +79,15 @@ struct nd_opt_hdr {
 	__u8		nd_opt_len;
 } __packed;
 
+static inline u32 ndisc_hashfn(const void *pkey, const struct net_device *dev, __u32 *hash_rnd)
+{
+	const u32 *p32 = pkey;
+
+	return (((p32[0] ^ dev->ifindex) * hash_rnd[0]) +
+		(p32[1] * hash_rnd[1]) +
+		(p32[2] * hash_rnd[2]) +
+		(p32[3] * hash_rnd[3]));
+}
 
 extern int			ndisc_init(void);
 
diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index e31f0a8..34c996f 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -139,10 +139,12 @@ struct pneigh_entry {
  *	neighbour table manipulation
  */
 
+#define NEIGH_NUM_HASH_RND	4
+
 struct neigh_hash_table {
 	struct neighbour __rcu	**hash_buckets;
 	unsigned int		hash_shift;
-	__u32			hash_rnd;
+	__u32			hash_rnd[NEIGH_NUM_HASH_RND];
 	struct rcu_head		rcu;
 };
 
@@ -154,7 +156,7 @@ struct neigh_table {
 	int			key_len;
 	__u32			(*hash)(const void *pkey,
 					const struct net_device *dev,
-					__u32 hash_rnd);
+					__u32 *hash_rnd);
 	int			(*constructor)(struct neighbour *);
 	int			(*pconstructor)(struct pneigh_entry *);
 	void			(*pdestructor)(struct pneigh_entry *);