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>

7 files changed, 32 insertions, 21 deletions

diff --git a/include/net/arp.h b/include/net/arp.h
index 4979af8b1559..0013dc87940b 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 c977c377c015..e9c30023b784 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 e31f0a86f9b7..34c996f46181 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 *);
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 4af151e1bf5d..e287346e0934 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -322,11 +322,18 @@ out_entries:
         goto out;
 }
 
+static void neigh_get_hash_rnd(u32 *x)
+{
+        get_random_bytes(x, sizeof(*x));
+        *x |= 1;
+}
+
 static struct neigh_hash_table *neigh_hash_alloc(unsigned int shift)
 {
         size_t size = (1 << shift) * sizeof(struct neighbour *);
         struct neigh_hash_table *ret;
         struct neighbour __rcu **buckets;
+        int i;
 
         ret = kmalloc(sizeof(*ret), GFP_ATOMIC);
         if (!ret)
@@ -343,8 +350,8 @@ static struct neigh_hash_table *neigh_hash_alloc(unsigned int shift)
         }
         ret->hash_buckets = buckets;
         ret->hash_shift = shift;
-        get_random_bytes(&ret->hash_rnd, sizeof(ret->hash_rnd));
-        ret->hash_rnd |= 1;
+        for (i = 0; i < NEIGH_NUM_HASH_RND; i++)
+                neigh_get_hash_rnd(&ret->hash_rnd[i]);
         return ret;
 }
 
@@ -1828,7 +1835,7 @@ static int neightbl_fill_info(struct sk_buff *skb, struct neigh_table *tbl,
 
                 rcu_read_lock_bh();
                 nht = rcu_dereference_bh(tbl->nht);
-                ndc.ndtc_hash_rnd = nht->hash_rnd;
+                ndc.ndtc_hash_rnd = nht->hash_rnd[0];
                 ndc.ndtc_hash_mask = ((1 << nht->hash_shift) - 1);
                 rcu_read_unlock_bh();
 
diff --git a/net/decnet/dn_neigh.c b/net/decnet/dn_neigh.c
index 7d2fff29380f..befe426491ba 100644
--- a/net/decnet/dn_neigh.c
+++ b/net/decnet/dn_neigh.c
@@ -88,9 +88,9 @@ static const struct neigh_ops dn_phase3_ops = {
 
 static u32 dn_neigh_hash(const void *pkey,
                          const struct net_device *dev,
-                         __u32 hash_rnd)
+                         __u32 *hash_rnd)
 {
-        return jhash_2words(*(__u16 *)pkey, 0, hash_rnd);
+        return jhash_2words(*(__u16 *)pkey, 0, hash_rnd[0]);
 }
 
 struct neigh_table dn_neigh_table = {
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 381a0876c363..59402be133f0 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -121,7 +121,7 @@
 /*
  *      Interface to generic neighbour cache.
  */
-static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 rnd);
+static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
 static int arp_constructor(struct neighbour *neigh);
 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
@@ -215,9 +215,9 @@ int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
 
 static u32 arp_hash(const void *pkey,
                     const struct net_device *dev,
-                    __u32 hash_rnd)
+                    __u32 *hash_rnd)
 {
-        return arp_hashfn(*(u32 *)pkey, dev, hash_rnd);
+        return arp_hashfn(*(u32 *)pkey, dev, *hash_rnd);
 }
 
 static int arp_constructor(struct neighbour *neigh)
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index f3e50c29add4..538a61960a24 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -93,7 +93,7 @@
 
 static u32 ndisc_hash(const void *pkey,
                       const struct net_device *dev,
-                      __u32 rnd);
+                      __u32 *hash_rnd);
 static int ndisc_constructor(struct neighbour *neigh);
 static void ndisc_solicit(struct neighbour *neigh, struct sk_buff *skb);
 static void ndisc_error_report(struct neighbour *neigh, struct sk_buff *skb);
@@ -349,16 +349,9 @@ EXPORT_SYMBOL(ndisc_mc_map);
 
 static u32 ndisc_hash(const void *pkey,
                       const struct net_device *dev,
-                      __u32 hash_rnd)
+                      __u32 *hash_rnd)
 {
-        const u32 *p32 = pkey;
-        u32 addr_hash, i;
-
-        addr_hash = 0;
-        for (i = 0; i < (sizeof(struct in6_addr) / sizeof(u32)); i++)
-                addr_hash ^= *p32++;
-
-        return jhash_2words(addr_hash, dev->ifindex, hash_rnd);
+        return ndisc_hashfn(pkey, dev, hash_rnd);
 }
 
 static int ndisc_constructor(struct neighbour *neigh)