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>

diff --git a/include/net/arp.h b/include/net/arp.h
index 4979af8b15599adcbc6309c902be3caa325b6e67..0013dc87940bf17c77a1a0c083b60c5c2f6a0a57 100644 (file)
--- 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 c977c377c015c84df1a3dffc9d3729551c4653a1..e9c30023b784ab376eb7755bbaaf788ef5bb9e20 100644 (file)
--- 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 e31f0a86f9b74527026d8fa3d0db035e403c3a4a..34c996f4618139329c98b272de08b94328abab38 100644 (file)
--- 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 4af151e1bf5dbcfd2abffc432e0b57e7a2a21877..e287346e09343f1f315866fc7e77fb3770d927b0 100644 (file)
--- 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 7d2fff29380f9b8cb9bab12061989eb7485fb319..befe426491ba0c793ac176ed9d3994f5d73e9b31 100644 (file)
--- 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 381a0876c363c11400ee920130875a4be0715f07..59402be133f0b4cced6dac7d22fea61fcf89dda6 100644 (file)
--- 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 f3e50c29add42a1ce66d137c8cd77bfa9174ddc3..538a61960a24791d2ad899def392ec9ed2b275d3 100644 (file)
--- 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)