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ipv6: Use universal hash for NDISC.

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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>
This commit is contained in:
David S. Miller 2011-12-28 15:06:58 -05:00
parent 32288eb4d9
commit 2c2aba6c56
7 changed files with 32 additions and 21 deletions
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2
include/net/arp.h
View file

@ -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)) {

9
include/net/ndisc.h
View file

@ -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);

6
include/net/neighbour.h
View file

@ -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 *);

13
net/core/neighbour.c
View file

@ -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();

4
net/decnet/dn_neigh.c
View file

@ -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 = {

6
net/ipv4/arp.c
View file

@ -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)

13
net/ipv6/ndisc.c
View file

@ -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)