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Date: Wed, 28 Dec 2011 15:14:49 -0500 (EST)
From: David Miller <davem@...emloft.net>
To: netdev@...r.kernel.org
Subject: [PATCH] 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@...emloft.net>
---
Committed to net-next
include/net/arp.h | 2 +-
include/net/ndisc.h | 9 +++++++++
include/net/neighbour.h | 6 ++++--
net/core/neighbour.c | 13 ++++++++++---
net/decnet/dn_neigh.c | 4 ++--
net/ipv4/arp.c | 6 +++---
net/ipv6/ndisc.c | 13 +++----------
7 files changed, 32 insertions(+), 21 deletions(-)
diff --git a/include/net/arp.h b/include/net/arp.h
index 4979af8..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 *);
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 4af151e..e287346 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 7d2fff2..befe426 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 381a087..59402be 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 f3e50c2..538a619 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)
--
1.7.7.4
--
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