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netfilter: nf_tables: handle chain name lookups via rhltable
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If there is a significant amount of chains list search is too slow, so
add an rhlist table for this.

This speeds up ruleset loading: for every new rule we have to check if
the name already exists in current generation.

We need to be able to cope with duplicate chain names in case a transaction
drops the nfnl mutex (for request_module) and the abort of this old
transaction is still pending.

The list is kept -- we need a way to iterate chains even if hash resize is
in progress without missing an entry.

Signed-off-by: Florian Westphal <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>
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@ummakynes
Florian Westphal authored and ummakynes committed Jun 2, 2018
1 parent 290180e commit 1b2470e
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Showing 2 changed files with 104 additions and 16 deletions.
7 changes: 6 additions & 1 deletion include/net/netfilter/nf_tables.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/nf_tables.h>
#include <linux/u64_stats_sync.h>
#include <linux/rhashtable.h>
#include <net/netfilter/nf_flow_table.h>
#include <net/netlink.h>

Expand Down Expand Up @@ -860,6 +861,7 @@ enum nft_chain_flags {
*
* @rules: list of rules in the chain
* @list: used internally
* @rhlhead: used internally
* @table: table that this chain belongs to
* @handle: chain handle
* @use: number of jump references to this chain
Expand All @@ -872,6 +874,7 @@ struct nft_chain {
struct nft_rule *__rcu *rules_gen_1;
struct list_head rules;
struct list_head list;
struct rhlist_head rhlhead;
struct nft_table *table;
u64 handle;
u32 use;
Expand Down Expand Up @@ -965,7 +968,8 @@ unsigned int nft_do_chain(struct nft_pktinfo *pkt, void *priv);
* struct nft_table - nf_tables table
*
* @list: used internally
* @chains: chains in the table
* @chains_ht: chains in the table
* @chains: same, for stable walks
* @sets: sets in the table
* @objects: stateful objects in the table
* @flowtables: flow tables in the table
Expand All @@ -979,6 +983,7 @@ unsigned int nft_do_chain(struct nft_pktinfo *pkt, void *priv);
*/
struct nft_table {
struct list_head list;
struct rhltable chains_ht;
struct list_head chains;
struct list_head sets;
struct list_head objects;
Expand Down
113 changes: 98 additions & 15 deletions net/netfilter/nf_tables_api.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,20 @@ enum {
NFT_VALIDATE_DO,
};

static u32 nft_chain_hash(const void *data, u32 len, u32 seed);
static u32 nft_chain_hash_obj(const void *data, u32 len, u32 seed);
static int nft_chain_hash_cmp(struct rhashtable_compare_arg *, const void *);

static const struct rhashtable_params nft_chain_ht_params = {
.head_offset = offsetof(struct nft_chain, rhlhead),
.key_offset = offsetof(struct nft_chain, name),
.hashfn = nft_chain_hash,
.obj_hashfn = nft_chain_hash_obj,
.obj_cmpfn = nft_chain_hash_cmp,
.locks_mul = 1,
.automatic_shrinking = true,
};

static void nft_validate_state_update(struct net *net, u8 new_validate_state)
{
switch (net->nft.validate_state) {
Expand Down Expand Up @@ -720,6 +734,29 @@ static int nf_tables_updtable(struct nft_ctx *ctx)
return ret;
}

static u32 nft_chain_hash(const void *data, u32 len, u32 seed)
{
const char *name = data;

return jhash(name, strlen(name), seed);
}

static u32 nft_chain_hash_obj(const void *data, u32 len, u32 seed)
{
const struct nft_chain *chain = data;

return nft_chain_hash(chain->name, 0, seed);
}

static int nft_chain_hash_cmp(struct rhashtable_compare_arg *arg,
const void *ptr)
{
const struct nft_chain *chain = ptr;
const char *name = arg->key;

return strcmp(chain->name, name);
}

static int nf_tables_newtable(struct net *net, struct sock *nlsk,
struct sk_buff *skb, const struct nlmsghdr *nlh,
const struct nlattr * const nla[],
Expand Down Expand Up @@ -766,6 +803,10 @@ static int nf_tables_newtable(struct net *net, struct sock *nlsk,
if (table->name == NULL)
goto err_strdup;

err = rhltable_init(&table->chains_ht, &nft_chain_ht_params);
if (err)
goto err_chain_ht;

INIT_LIST_HEAD(&table->chains);
INIT_LIST_HEAD(&table->sets);
INIT_LIST_HEAD(&table->objects);
Expand All @@ -782,6 +823,8 @@ static int nf_tables_newtable(struct net *net, struct sock *nlsk,
list_add_tail_rcu(&table->list, &net->nft.tables);
return 0;
err_trans:
rhltable_destroy(&table->chains_ht);
err_chain_ht:
kfree(table->name);
err_strdup:
kfree(table);
Expand Down Expand Up @@ -922,6 +965,7 @@ static void nf_tables_table_destroy(struct nft_ctx *ctx)
{
BUG_ON(ctx->table->use > 0);

rhltable_destroy(&ctx->table->chains_ht);
kfree(ctx->table->name);
kfree(ctx->table);
}
Expand Down Expand Up @@ -967,21 +1011,35 @@ nft_chain_lookup_byhandle(const struct nft_table *table, u64 handle, u8 genmask)
return ERR_PTR(-ENOENT);
}

static struct nft_chain *nft_chain_lookup(const struct nft_table *table,
static struct nft_chain *nft_chain_lookup(struct nft_table *table,
const struct nlattr *nla, u8 genmask)
{
char search[NFT_CHAIN_MAXNAMELEN + 1];
struct rhlist_head *tmp, *list;
struct nft_chain *chain;

if (nla == NULL)
return ERR_PTR(-EINVAL);

list_for_each_entry_rcu(chain, &table->chains, list) {
if (!nla_strcmp(nla, chain->name) &&
nft_active_genmask(chain, genmask))
return chain;
}
nla_strlcpy(search, nla, sizeof(search));

return ERR_PTR(-ENOENT);
WARN_ON(!rcu_read_lock_held() &&
!lockdep_nfnl_is_held(NFNL_SUBSYS_NFTABLES));

chain = ERR_PTR(-ENOENT);
rcu_read_lock();
list = rhltable_lookup(&table->chains_ht, search, nft_chain_ht_params);
if (!list)
goto out_unlock;

rhl_for_each_entry_rcu(chain, tmp, list, rhlhead) {
if (nft_active_genmask(chain, genmask))
goto out_unlock;
}
chain = ERR_PTR(-ENOENT);
out_unlock:
rcu_read_unlock();
return chain;
}

static const struct nla_policy nft_chain_policy[NFTA_CHAIN_MAX + 1] = {
Expand Down Expand Up @@ -1185,8 +1243,8 @@ static int nf_tables_getchain(struct net *net, struct sock *nlsk,
{
const struct nfgenmsg *nfmsg = nlmsg_data(nlh);
u8 genmask = nft_genmask_cur(net);
const struct nft_table *table;
const struct nft_chain *chain;
struct nft_table *table;
struct sk_buff *skb2;
int family = nfmsg->nfgen_family;
int err;
Expand Down Expand Up @@ -1504,9 +1562,17 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
if (err < 0)
goto err1;

err = rhltable_insert_key(&table->chains_ht, chain->name,
&chain->rhlhead, nft_chain_ht_params);
if (err)
goto err2;

err = nft_trans_chain_add(ctx, NFT_MSG_NEWCHAIN);
if (err < 0)
if (err < 0) {
rhltable_remove(&table->chains_ht, &chain->rhlhead,
nft_chain_ht_params);
goto err2;
}

table->use++;
list_add_tail_rcu(&chain->list, &table->chains);
Expand Down Expand Up @@ -2206,9 +2272,9 @@ static int nf_tables_getrule(struct net *net, struct sock *nlsk,
{
const struct nfgenmsg *nfmsg = nlmsg_data(nlh);
u8 genmask = nft_genmask_cur(net);
const struct nft_table *table;
const struct nft_chain *chain;
const struct nft_rule *rule;
struct nft_table *table;
struct sk_buff *skb2;
int family = nfmsg->nfgen_family;
int err;
Expand Down Expand Up @@ -5981,8 +6047,16 @@ static void nft_chain_commit_update(struct nft_trans *trans)
{
struct nft_base_chain *basechain;

if (nft_trans_chain_name(trans))
if (nft_trans_chain_name(trans)) {
rhltable_remove(&trans->ctx.table->chains_ht,
&trans->ctx.chain->rhlhead,
nft_chain_ht_params);
swap(trans->ctx.chain->name, nft_trans_chain_name(trans));
rhltable_insert_key(&trans->ctx.table->chains_ht,
trans->ctx.chain->name,
&trans->ctx.chain->rhlhead,
nft_chain_ht_params);
}

if (!nft_is_base_chain(trans->ctx.chain))
return;
Expand Down Expand Up @@ -6159,6 +6233,15 @@ static void nf_tables_commit_chain_active(struct net *net, struct nft_chain *cha
nf_tables_commit_chain_free_rules_old(g0);
}

static void nft_chain_del(struct nft_chain *chain)
{
struct nft_table *table = chain->table;

WARN_ON_ONCE(rhltable_remove(&table->chains_ht, &chain->rhlhead,
nft_chain_ht_params));
list_del_rcu(&chain->list);
}

static int nf_tables_commit(struct net *net, struct sk_buff *skb)
{
struct nft_trans *trans, *next;
Expand Down Expand Up @@ -6233,7 +6316,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
nft_trans_destroy(trans);
break;
case NFT_MSG_DELCHAIN:
list_del_rcu(&trans->ctx.chain->list);
nft_chain_del(trans->ctx.chain);
nf_tables_chain_notify(&trans->ctx, NFT_MSG_DELCHAIN);
nf_tables_unregister_hook(trans->ctx.net,
trans->ctx.table,
Expand Down Expand Up @@ -6384,7 +6467,7 @@ static int nf_tables_abort(struct net *net, struct sk_buff *skb)
nft_trans_destroy(trans);
} else {
trans->ctx.table->use--;
list_del_rcu(&trans->ctx.chain->list);
nft_chain_del(trans->ctx.chain);
nf_tables_unregister_hook(trans->ctx.net,
trans->ctx.table,
trans->ctx.chain);
Expand Down Expand Up @@ -6986,7 +7069,7 @@ int __nft_release_basechain(struct nft_ctx *ctx)
ctx->chain->use--;
nf_tables_rule_release(ctx, rule);
}
list_del(&ctx->chain->list);
nft_chain_del(ctx->chain);
ctx->table->use--;
nf_tables_chain_destroy(ctx);

Expand Down Expand Up @@ -7042,7 +7125,7 @@ static void __nft_release_tables(struct net *net)
}
list_for_each_entry_safe(chain, nc, &table->chains, list) {
ctx.chain = chain;
list_del(&chain->list);
nft_chain_del(chain);
table->use--;
nf_tables_chain_destroy(&ctx);
}
Expand Down

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