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Commit 870190a9 authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso
Browse files

netfilter: nat: convert nat bysrc hash to rhashtable 



It did use a fixed-size bucket list plus single lock to protect add/del.

Unlike the main conntrack table we only need to add and remove keys.
Convert it to rhashtable to get table autosizing and per-bucket locking.

The maximum number of entries is -- as before -- tied to the number of
conntracks so we do not need another upperlimit.

The change does not handle rhashtable_remove_fast error, only possible
"error" is -ENOENT, and that is something that can happen legitimetely,
e.g. because nat module was inserted at a later time and no src manip
took place yet.

Tested with http-client-benchmark + httpterm with DNAT and SNAT rules
in place.

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 7c966435

include/net/netfilter/nf_conntrack.h

+2 −1
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/bitops.h>

#include <linux/compiler.h>

#include <linux/atomic.h>

#include <linux/rhashtable.h>



#include <linux/netfilter/nf_conntrack_tcp.h>

#include <linux/netfilter/nf_conntrack_dccp.h>
@@ -118,7 +119,7 @@ struct nf_conn { 
	struct nf_ct_ext *ext;



#if IS_ENABLED(CONFIG_NF_NAT)

	struct hlist_node	nat_bysource;

	struct rhash_head	nat_bysource;

#endif

	/* Storage reserved for other modules, must be the last member */

	union nf_conntrack_proto proto;

include/net/netfilter/nf_nat.h

+1 −0
Original line number Diff line number Diff line 
#ifndef _NF_NAT_H

#define _NF_NAT_H

#include <linux/rhashtable.h>

#include <linux/netfilter_ipv4.h>

#include <linux/netfilter/nf_nat.h>

#include <net/netfilter/nf_conntrack_tuple.h>

net/netfilter/nf_nat_core.c

+68 −58
Original line number Diff line number Diff line
@@ -30,17 +30,19 @@ 
#include <net/netfilter/nf_conntrack_zones.h>

#include <linux/netfilter/nf_nat.h>



static DEFINE_SPINLOCK(nf_nat_lock);



static DEFINE_MUTEX(nf_nat_proto_mutex);

static const struct nf_nat_l3proto __rcu *nf_nat_l3protos[NFPROTO_NUMPROTO]

						__read_mostly;

static const struct nf_nat_l4proto __rcu **nf_nat_l4protos[NFPROTO_NUMPROTO]

						__read_mostly;



static struct hlist_head *nf_nat_bysource __read_mostly;

static unsigned int nf_nat_htable_size __read_mostly;

static unsigned int nf_nat_hash_rnd __read_mostly;

struct nf_nat_conn_key {

	const struct net *net;

	const struct nf_conntrack_tuple *tuple;

	const struct nf_conntrack_zone *zone;

};



static struct rhashtable nf_nat_bysource_table;



inline const struct nf_nat_l3proto *

__nf_nat_l3proto_find(u8 family)
@@ -119,19 +121,17 @@ int nf_xfrm_me_harder(struct net *net, struct sk_buff *skb, unsigned int family) 
EXPORT_SYMBOL(nf_xfrm_me_harder);

#endif /* CONFIG_XFRM */



/* We keep an extra hash for each conntrack, for fast searching. */

static inline unsigned int

hash_by_src(const struct net *n, const struct nf_conntrack_tuple *tuple)

static u32 nf_nat_bysource_hash(const void *data, u32 len, u32 seed)

{

	unsigned int hash;



	get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd));

	const struct nf_conntrack_tuple *t;

	const struct nf_conn *ct = data;



	t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;

	/* Original src, to ensure we map it consistently if poss. */

	hash = jhash2((u32 *)&tuple->src, sizeof(tuple->src) / sizeof(u32),

		      tuple->dst.protonum ^ nf_nat_hash_rnd ^ net_hash_mix(n));



	return reciprocal_scale(hash, nf_nat_htable_size);

	seed ^= net_hash_mix(nf_ct_net(ct));

	return jhash2((const u32 *)&t->src, sizeof(t->src) / sizeof(u32),

		      t->dst.protonum ^ seed);

}



/* Is this tuple already taken? (not by us) */
@@ -187,6 +187,26 @@ same_src(const struct nf_conn *ct, 
		t->src.u.all == tuple->src.u.all);

}



static int nf_nat_bysource_cmp(struct rhashtable_compare_arg *arg,

			       const void *obj)

{

	const struct nf_nat_conn_key *key = arg->key;

	const struct nf_conn *ct = obj;



	return same_src(ct, key->tuple) &&

	       net_eq(nf_ct_net(ct), key->net) &&

	       nf_ct_zone_equal(ct, key->zone, IP_CT_DIR_ORIGINAL);

}



static struct rhashtable_params nf_nat_bysource_params = {

	.head_offset = offsetof(struct nf_conn, nat_bysource),

	.obj_hashfn = nf_nat_bysource_hash,

	.obj_cmpfn = nf_nat_bysource_cmp,

	.nelem_hint = 256,

	.min_size = 1024,

	.nulls_base = (1U << RHT_BASE_SHIFT),

};



/* Only called for SRC manip */

static int

find_appropriate_src(struct net *net,
@@ -197,23 +217,23 @@ find_appropriate_src(struct net *net, 
		     struct nf_conntrack_tuple *result,

		     const struct nf_nat_range *range)

{

	unsigned int h = hash_by_src(net, tuple);

	const struct nf_conn *ct;

	struct nf_nat_conn_key key = {

		.net = net,

		.tuple = tuple,

		.zone = zone

	};



	ct = rhashtable_lookup_fast(&nf_nat_bysource_table, &key,

				    nf_nat_bysource_params);

	if (!ct)

		return 0;



	hlist_for_each_entry_rcu(ct, &nf_nat_bysource[h], nat_bysource) {

		if (same_src(ct, tuple) &&

		    net_eq(net, nf_ct_net(ct)) &&

		    nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL)) {

			/* Copy source part from reply tuple. */

	nf_ct_invert_tuplepr(result,

			     &ct->tuplehash[IP_CT_DIR_REPLY].tuple);

	result->dst = tuple->dst;



			if (in_range(l3proto, l4proto, result, range))

				return 1;

		}

	}

	return 0;

	return in_range(l3proto, l4proto, result, range);

}



/* For [FUTURE] fragmentation handling, we want the least-used
@@ -385,7 +405,6 @@ nf_nat_setup_info(struct nf_conn *ct, 
		  const struct nf_nat_range *range,

		  enum nf_nat_manip_type maniptype)

{

	struct net *net = nf_ct_net(ct);

	struct nf_conntrack_tuple curr_tuple, new_tuple;

	struct nf_conn_nat *nat;
@@ -426,16 +445,13 @@ nf_nat_setup_info(struct nf_conn *ct, 
	}



	if (maniptype == NF_NAT_MANIP_SRC) {

		unsigned int srchash;

		int err;



		srchash = hash_by_src(net,

				      &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);

		spin_lock_bh(&nf_nat_lock);

		/* nf_conntrack_alter_reply might re-allocate extension aera */

		nat = nfct_nat(ct);

		hlist_add_head_rcu(&ct->nat_bysource,

				   &nf_nat_bysource[srchash]);

		spin_unlock_bh(&nf_nat_lock);

		err = rhashtable_insert_fast(&nf_nat_bysource_table,

					     &ct->nat_bysource,

					     nf_nat_bysource_params);

		if (err)

			return NF_DROP;

	}



	/* It's done. */
@@ -552,10 +568,10 @@ static int nf_nat_proto_clean(struct nf_conn *ct, void *data) 
	if (!del_timer(&ct->timeout))

		return 1;



	spin_lock_bh(&nf_nat_lock);

	hlist_del_rcu(&ct->nat_bysource);

	ct->status &= ~IPS_NAT_DONE_MASK;

	spin_unlock_bh(&nf_nat_lock);



	rhashtable_remove_fast(&nf_nat_bysource_table, &ct->nat_bysource,

			       nf_nat_bysource_params);



	add_timer(&ct->timeout);
@@ -687,11 +703,8 @@ static void nf_nat_cleanup_conntrack(struct nf_conn *ct) 
	if (!nat)

		return;



	NF_CT_ASSERT(ct->status & IPS_SRC_NAT_DONE);



	spin_lock_bh(&nf_nat_lock);

	hlist_del_rcu(&ct->nat_bysource);

	spin_unlock_bh(&nf_nat_lock);

	rhashtable_remove_fast(&nf_nat_bysource_table, &ct->nat_bysource,

			       nf_nat_bysource_params);

}



static struct nf_ct_ext_type nat_extend __read_mostly = {
@@ -826,16 +839,13 @@ static int __init nf_nat_init(void) 
{

	int ret;



	/* Leave them the same for the moment. */

	nf_nat_htable_size = nf_conntrack_htable_size;



	nf_nat_bysource = nf_ct_alloc_hashtable(&nf_nat_htable_size, 0);

	if (!nf_nat_bysource)

		return -ENOMEM;

	ret = rhashtable_init(&nf_nat_bysource_table, &nf_nat_bysource_params);

	if (ret)

		return ret;



	ret = nf_ct_extend_register(&nat_extend);

	if (ret < 0) {

		nf_ct_free_hashtable(nf_nat_bysource, nf_nat_htable_size);

		rhashtable_destroy(&nf_nat_bysource_table);

		printk(KERN_ERR "nf_nat_core: Unable to register extension\n");

		return ret;

	}
@@ -859,7 +869,7 @@ static int __init nf_nat_init(void) 
	return 0;



 cleanup_extend:

	nf_ct_free_hashtable(nf_nat_bysource, nf_nat_htable_size);

	rhashtable_destroy(&nf_nat_bysource_table);

	nf_ct_extend_unregister(&nat_extend);

	return ret;

}
@@ -877,8 +887,8 @@ static void __exit nf_nat_cleanup(void) 
#endif

	for (i = 0; i < NFPROTO_NUMPROTO; i++)

		kfree(nf_nat_l4protos[i]);

	synchronize_net();

	nf_ct_free_hashtable(nf_nat_bysource, nf_nat_htable_size);



	rhashtable_destroy(&nf_nat_bysource_table);

}



MODULE_LICENSE("GPL");