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Commit 2c2aba6c authored by David S. Miller's avatar David S. Miller
Browse files

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: default avatarDavid S. Miller <davem@davemloft.net>
parent 32288eb4

include/net/arp.h

+1 −1
Original line number Diff line number Diff line
@@ -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)) {

include/net/ndisc.h

+9 −0
Original line number Diff line number Diff line
@@ -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);

include/net/neighbour.h

+4 −2
Original line number Diff line number Diff line
@@ -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 *);

net/core/neighbour.c

+10 −3
Original line number Diff line number Diff line
@@ -322,11 +322,18 @@ static struct neighbour *neigh_alloc(struct neigh_table *tbl, struct net_device 
	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();

net/decnet/dn_neigh.c

+2 −2
Original line number Diff line number Diff line
@@ -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 = {