netfilter: nat: Revert "netfilter: nat: convert nat bysrc hash to rhashtable"
This reverts commit 870190a9ec.
It was not a good idea. The custom hash table was a much better
fit for this purpose.
A fast lookup is not essential, in fact for most cases there is no lookup
at all because original tuple is not taken and can be used as-is.
What needs to be fast is insertion and deletion.
rhlist removal however requires a rhlist walk.
We can have thousands of entries in such a list if source port/addresses
are reused for multiple flows, if this happens removal requests are so
expensive that deletions of a few thousand flows can take several
seconds(!).
The advantages that we got from rhashtable are:
1) table auto-sizing
2) multiple locks
1) would be nice to have, but it is not essential as we have at
most one lookup per new flow, so even a million flows in the bysource
table are not a problem compared to current deletion cost.
2) is easy to add to custom hash table.
I tried to add hlist_node to rhlist to speed up rhltable_remove but this
isn't doable without changing semantics. rhltable_remove_fast will
check that the to-be-deleted object is part of the table and that
requires a list walk that we want to avoid.
Furthermore, using hlist_node increases size of struct rhlist_head, which
in turn increases nf_conn size.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=196821
Reported-by: Ivan Babrou <ibobrik@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal
Pablo Neira Ayuso
Родитель
a5d7a71456
Коммит
e1bf168774
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@ -17,7 +17,6 @@
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#include <linux/bitops.h>
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#include <linux/compiler.h>
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#include <linux/atomic.h>
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#include <linux/rhashtable.h>
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#include <linux/netfilter/nf_conntrack_tcp.h>
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#include <linux/netfilter/nf_conntrack_dccp.h>
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@ -77,7 +76,7 @@ struct nf_conn {
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possible_net_t ct_net;
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#if IS_ENABLED(CONFIG_NF_NAT)
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struct rhlist_head nat_bysource;
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struct hlist_node nat_bysource;
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#endif
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/* all members below initialized via memset */
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u8 __nfct_init_offset[0];
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@ -1,6 +1,5 @@
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#ifndef _NF_NAT_H
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#define _NF_NAT_H
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#include <linux/rhashtable.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter/nf_nat.h>
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#include <net/netfilter/nf_conntrack_tuple.h>
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@ -30,19 +30,17 @@
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#include <net/netfilter/nf_conntrack_zones.h>
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#include <linux/netfilter/nf_nat.h>
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static DEFINE_SPINLOCK(nf_nat_lock);
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static DEFINE_MUTEX(nf_nat_proto_mutex);
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static const struct nf_nat_l3proto __rcu *nf_nat_l3protos[NFPROTO_NUMPROTO]
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__read_mostly;
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static const struct nf_nat_l4proto __rcu **nf_nat_l4protos[NFPROTO_NUMPROTO]
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__read_mostly;
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struct nf_nat_conn_key {
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const struct net *net;
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const struct nf_conntrack_tuple *tuple;
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const struct nf_conntrack_zone *zone;
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};
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static struct rhltable nf_nat_bysource_table;
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static struct hlist_head *nf_nat_bysource __read_mostly;
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static unsigned int nf_nat_htable_size __read_mostly;
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static unsigned int nf_nat_hash_rnd __read_mostly;
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inline const struct nf_nat_l3proto *
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__nf_nat_l3proto_find(u8 family)
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@ -118,17 +116,19 @@ int nf_xfrm_me_harder(struct net *net, struct sk_buff *skb, unsigned int family)
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EXPORT_SYMBOL(nf_xfrm_me_harder);
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#endif /* CONFIG_XFRM */
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static u32 nf_nat_bysource_hash(const void *data, u32 len, u32 seed)
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/* We keep an extra hash for each conntrack, for fast searching. */
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static unsigned int
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hash_by_src(const struct net *n, const struct nf_conntrack_tuple *tuple)
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{
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const struct nf_conntrack_tuple *t;
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const struct nf_conn *ct = data;
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unsigned int hash;
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get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd));
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t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
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/* Original src, to ensure we map it consistently if poss. */
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hash = jhash2((u32 *)&tuple->src, sizeof(tuple->src) / sizeof(u32),
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tuple->dst.protonum ^ nf_nat_hash_rnd ^ net_hash_mix(n));
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seed ^= net_hash_mix(nf_ct_net(ct));
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return jhash2((const u32 *)&t->src, sizeof(t->src) / sizeof(u32),
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t->dst.protonum ^ seed);
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return reciprocal_scale(hash, nf_nat_htable_size);
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}
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/* Is this tuple already taken? (not by us) */
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@ -184,28 +184,6 @@ same_src(const struct nf_conn *ct,
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t->src.u.all == tuple->src.u.all);
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}
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static int nf_nat_bysource_cmp(struct rhashtable_compare_arg *arg,
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const void *obj)
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{
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const struct nf_nat_conn_key *key = arg->key;
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const struct nf_conn *ct = obj;
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if (!same_src(ct, key->tuple) ||
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!net_eq(nf_ct_net(ct), key->net) ||
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!nf_ct_zone_equal(ct, key->zone, IP_CT_DIR_ORIGINAL))
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return 1;
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return 0;
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}
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static struct rhashtable_params nf_nat_bysource_params = {
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.head_offset = offsetof(struct nf_conn, nat_bysource),
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.obj_hashfn = nf_nat_bysource_hash,
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.obj_cmpfn = nf_nat_bysource_cmp,
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.nelem_hint = 256,
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.min_size = 1024,
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};
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/* Only called for SRC manip */
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static int
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find_appropriate_src(struct net *net,
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@ -216,26 +194,22 @@ find_appropriate_src(struct net *net,
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struct nf_conntrack_tuple *result,
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const struct nf_nat_range *range)
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{
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unsigned int h = hash_by_src(net, tuple);
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const struct nf_conn *ct;
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struct nf_nat_conn_key key = {
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.net = net,
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.tuple = tuple,
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.zone = zone
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};
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struct rhlist_head *hl, *h;
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hl = rhltable_lookup(&nf_nat_bysource_table, &key,
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nf_nat_bysource_params);
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hlist_for_each_entry_rcu(ct, &nf_nat_bysource[h], nat_bysource) {
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if (same_src(ct, tuple) &&
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net_eq(net, nf_ct_net(ct)) &&
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nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL)) {
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/* Copy source part from reply tuple. */
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nf_ct_invert_tuplepr(result,
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&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
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result->dst = tuple->dst;
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rhl_for_each_entry_rcu(ct, h, hl, nat_bysource) {
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nf_ct_invert_tuplepr(result,
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&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
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result->dst = tuple->dst;
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if (in_range(l3proto, l4proto, result, range))
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return 1;
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if (in_range(l3proto, l4proto, result, range))
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return 1;
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}
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}
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return 0;
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}
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@ -408,6 +382,7 @@ nf_nat_setup_info(struct nf_conn *ct,
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const struct nf_nat_range *range,
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enum nf_nat_manip_type maniptype)
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{
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struct net *net = nf_ct_net(ct);
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struct nf_conntrack_tuple curr_tuple, new_tuple;
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/* Can't setup nat info for confirmed ct. */
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@ -449,19 +424,14 @@ nf_nat_setup_info(struct nf_conn *ct,
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}
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if (maniptype == NF_NAT_MANIP_SRC) {
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struct nf_nat_conn_key key = {
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.net = nf_ct_net(ct),
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.tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
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.zone = nf_ct_zone(ct),
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};
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int err;
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unsigned int srchash;
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err = rhltable_insert_key(&nf_nat_bysource_table,
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&key,
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&ct->nat_bysource,
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nf_nat_bysource_params);
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if (err)
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return NF_DROP;
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srchash = hash_by_src(net,
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&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
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spin_lock_bh(&nf_nat_lock);
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hlist_add_head_rcu(&ct->nat_bysource,
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&nf_nat_bysource[srchash]);
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spin_unlock_bh(&nf_nat_lock);
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}
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/* It's done. */
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@ -570,8 +540,9 @@ static int nf_nat_proto_clean(struct nf_conn *ct, void *data)
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* will delete entry from already-freed table.
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*/
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clear_bit(IPS_SRC_NAT_DONE_BIT, &ct->status);
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rhltable_remove(&nf_nat_bysource_table, &ct->nat_bysource,
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nf_nat_bysource_params);
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spin_lock_bh(&nf_nat_lock);
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hlist_del_rcu(&ct->nat_bysource);
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spin_unlock_bh(&nf_nat_lock);
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/* don't delete conntrack. Although that would make things a lot
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* simpler, we'd end up flushing all conntracks on nat rmmod.
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@ -699,9 +670,11 @@ EXPORT_SYMBOL_GPL(nf_nat_l3proto_unregister);
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/* No one using conntrack by the time this called. */
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static void nf_nat_cleanup_conntrack(struct nf_conn *ct)
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{
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if (ct->status & IPS_SRC_NAT_DONE)
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rhltable_remove(&nf_nat_bysource_table, &ct->nat_bysource,
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nf_nat_bysource_params);
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if (ct->status & IPS_SRC_NAT_DONE) {
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spin_lock_bh(&nf_nat_lock);
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hlist_del_rcu(&ct->nat_bysource);
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spin_unlock_bh(&nf_nat_lock);
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}
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}
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static struct nf_ct_ext_type nat_extend __read_mostly = {
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@ -825,13 +798,16 @@ static int __init nf_nat_init(void)
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{
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int ret;
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ret = rhltable_init(&nf_nat_bysource_table, &nf_nat_bysource_params);
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if (ret)
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return ret;
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/* Leave them the same for the moment. */
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nf_nat_htable_size = nf_conntrack_htable_size;
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nf_nat_bysource = nf_ct_alloc_hashtable(&nf_nat_htable_size, 0);
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if (!nf_nat_bysource)
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return -ENOMEM;
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ret = nf_ct_extend_register(&nat_extend);
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if (ret < 0) {
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rhltable_destroy(&nf_nat_bysource_table);
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nf_ct_free_hashtable(nf_nat_bysource, nf_nat_htable_size);
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printk(KERN_ERR "nf_nat_core: Unable to register extension\n");
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return ret;
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}
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@ -865,8 +841,8 @@ static void __exit nf_nat_cleanup(void)
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for (i = 0; i < NFPROTO_NUMPROTO; i++)
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kfree(nf_nat_l4protos[i]);
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rhltable_destroy(&nf_nat_bysource_table);
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synchronize_net();
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nf_ct_free_hashtable(nf_nat_bysource, nf_nat_htable_size);
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}
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MODULE_LICENSE("GPL");
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