From 2c2aba6c561ac425602f4a0be61422224cb87151 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Wed, 28 Dec 2011 15:06:58 -0500 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 --- 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 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) -- 2.30.2