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netfilter: nft_set_hash: add non-resizable hashtable implementation
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This patch adds a simple non-resizable hashtable implementation. If the
user specifies the set size, then this new faster hashtable flavour is
selected.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Pablo Neira Ayuso committed May 29, 2017
1 parent 1ff75a3 commit 6c03ae2
Showing 1 changed file with 202 additions and 8 deletions.
210 changes: 202 additions & 8 deletions net/netfilter/nft_set_hash.c
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Original file line number Diff line number Diff line change
@@ -371,14 +371,181 @@ static u32 nft_hash_buckets(u32 size)
static bool nft_rhash_estimate(const struct nft_set_desc *desc, u32 features,
struct nft_set_estimate *est)
{
if (desc->size)
est->size = sizeof(struct nft_rhash) +
nft_hash_buckets(desc->size) *
sizeof(struct nft_rhash_elem *) +
desc->size * sizeof(struct nft_rhash_elem);
else
est->size = ~0;
est->size = ~0;
est->lookup = NFT_SET_CLASS_O_1;
est->space = NFT_SET_CLASS_O_N;

return true;
}

struct nft_hash {
u32 seed;
u32 buckets;
struct hlist_head table[];
};

struct nft_hash_elem {
struct hlist_node node;
struct nft_set_ext ext;
};

static bool nft_hash_lookup(const struct net *net, const struct nft_set *set,
const u32 *key, const struct nft_set_ext **ext)
{
struct nft_hash *priv = nft_set_priv(set);
u8 genmask = nft_genmask_cur(net);
const struct nft_hash_elem *he;
u32 hash;

hash = jhash(key, set->klen, priv->seed);
hash = reciprocal_scale(hash, priv->buckets);
hlist_for_each_entry_rcu(he, &priv->table[hash], node) {
if (!memcmp(nft_set_ext_key(&he->ext), key, set->klen) &&
nft_set_elem_active(&he->ext, genmask)) {
*ext = &he->ext;
return true;
}
}
return false;
}

static int nft_hash_insert(const struct net *net, const struct nft_set *set,
const struct nft_set_elem *elem,
struct nft_set_ext **ext)
{
struct nft_hash_elem *this = elem->priv, *he;
struct nft_hash *priv = nft_set_priv(set);
u8 genmask = nft_genmask_next(net);
u32 hash;

hash = jhash(nft_set_ext_key(&this->ext), set->klen, priv->seed);
hash = reciprocal_scale(hash, priv->buckets);
hlist_for_each_entry(he, &priv->table[hash], node) {
if (!memcmp(nft_set_ext_key(&this->ext),
nft_set_ext_key(&he->ext), set->klen) &&
nft_set_elem_active(&he->ext, genmask)) {
*ext = &he->ext;
return -EEXIST;
}
}
hlist_add_head_rcu(&this->node, &priv->table[hash]);
return 0;
}

static void nft_hash_activate(const struct net *net, const struct nft_set *set,
const struct nft_set_elem *elem)
{
struct nft_hash_elem *he = elem->priv;

nft_set_elem_change_active(net, set, &he->ext);
}

static bool nft_hash_flush(const struct net *net,
const struct nft_set *set, void *priv)
{
struct nft_hash_elem *he = priv;

nft_set_elem_change_active(net, set, &he->ext);
return true;
}

static void *nft_hash_deactivate(const struct net *net,
const struct nft_set *set,
const struct nft_set_elem *elem)
{
struct nft_hash *priv = nft_set_priv(set);
struct nft_hash_elem *this = elem->priv, *he;
u8 genmask = nft_genmask_next(net);
u32 hash;

hash = jhash(nft_set_ext_key(&this->ext), set->klen, priv->seed);
hash = reciprocal_scale(hash, priv->buckets);
hlist_for_each_entry(he, &priv->table[hash], node) {
if (!memcmp(nft_set_ext_key(&this->ext), &elem->key.val,
set->klen) ||
nft_set_elem_active(&he->ext, genmask)) {
nft_set_elem_change_active(net, set, &he->ext);
return he;
}
}
return NULL;
}

static void nft_hash_remove(const struct net *net,
const struct nft_set *set,
const struct nft_set_elem *elem)
{
struct nft_hash_elem *he = elem->priv;

hlist_del_rcu(&he->node);
}

static void nft_hash_walk(const struct nft_ctx *ctx, struct nft_set *set,
struct nft_set_iter *iter)
{
struct nft_hash *priv = nft_set_priv(set);
struct nft_hash_elem *he;
struct nft_set_elem elem;
int i;

for (i = 0; i < priv->buckets; i++) {
hlist_for_each_entry_rcu(he, &priv->table[i], node) {
if (iter->count < iter->skip)
goto cont;
if (!nft_set_elem_active(&he->ext, iter->genmask))
goto cont;

elem.priv = he;

iter->err = iter->fn(ctx, set, iter, &elem);
if (iter->err < 0)
return;
cont:
iter->count++;
}
}
}

static unsigned int nft_hash_privsize(const struct nlattr * const nla[],
const struct nft_set_desc *desc)
{
return sizeof(struct nft_hash) +
nft_hash_buckets(desc->size) * sizeof(struct hlist_head);
}

static int nft_hash_init(const struct nft_set *set,
const struct nft_set_desc *desc,
const struct nlattr * const tb[])
{
struct nft_hash *priv = nft_set_priv(set);

priv->buckets = nft_hash_buckets(desc->size);
get_random_bytes(&priv->seed, sizeof(priv->seed));

return 0;
}

static void nft_hash_destroy(const struct nft_set *set)
{
struct nft_hash *priv = nft_set_priv(set);
struct nft_hash_elem *he;
struct hlist_node *next;
int i;

for (i = 0; i < priv->buckets; i++) {
hlist_for_each_entry_safe(he, next, &priv->table[i], node) {
hlist_del_rcu(&he->node);
nft_set_elem_destroy(set, he, true);
}
}
}

static bool nft_hash_estimate(const struct nft_set_desc *desc, u32 features,
struct nft_set_estimate *est)
{
est->size = sizeof(struct nft_hash) +
nft_hash_buckets(desc->size) * sizeof(struct hlist_head) +
desc->size * sizeof(struct nft_hash_elem);
est->lookup = NFT_SET_CLASS_O_1;
est->space = NFT_SET_CLASS_O_N;

@@ -404,8 +571,35 @@ static struct nft_set_ops nft_rhash_ops __read_mostly = {
.features = NFT_SET_MAP | NFT_SET_OBJECT | NFT_SET_TIMEOUT,
};

static struct nft_set_ops nft_hash_ops __read_mostly = {
.type = &nft_hash_type,
.privsize = nft_hash_privsize,
.elemsize = offsetof(struct nft_hash_elem, ext),
.estimate = nft_hash_estimate,
.init = nft_hash_init,
.destroy = nft_hash_destroy,
.insert = nft_hash_insert,
.activate = nft_hash_activate,
.deactivate = nft_hash_deactivate,
.flush = nft_hash_flush,
.remove = nft_hash_remove,
.lookup = nft_hash_lookup,
.walk = nft_hash_walk,
.features = NFT_SET_MAP | NFT_SET_OBJECT,
};

static const struct nft_set_ops *
nft_hash_select_ops(const struct nft_ctx *ctx, const struct nft_set_desc *desc,
u32 flags)
{
if (desc->size)
return &nft_hash_ops;

return &nft_rhash_ops;
}

static struct nft_set_type nft_hash_type __read_mostly = {
.ops = &nft_rhash_ops,
.select_ops = nft_hash_select_ops,
.owner = THIS_MODULE,
};

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