--- /dev/null
+From e1bf1687740ce1a3598a1c5e452b852ff2190682 Mon Sep 17 00:00:00 2001
+From: Florian Westphal <fw@strlen.de>
+Date: Wed, 6 Sep 2017 14:39:51 +0200
+Subject: netfilter: nat: Revert "netfilter: nat: convert nat bysrc hash to rhashtable"
+
+From: Florian Westphal <fw@strlen.de>
+
+commit e1bf1687740ce1a3598a1c5e452b852ff2190682 upstream.
+
+This reverts commit 870190a9ec9075205c0fa795a09fa931694a3ff1.
+
+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>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+
+---
+ include/net/netfilter/nf_conntrack.h | 3
+ include/net/netfilter/nf_nat.h | 1
+ net/netfilter/nf_nat_core.c | 131 ++++++++++++++---------------------
+ 3 files changed, 56 insertions(+), 79 deletions(-)
+
+--- a/include/net/netfilter/nf_conntrack.h
++++ b/include/net/netfilter/nf_conntrack.h
+@@ -17,7 +17,6 @@
+ #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>
+@@ -101,7 +100,7 @@ struct nf_conn {
+ possible_net_t ct_net;
+
+ #if IS_ENABLED(CONFIG_NF_NAT)
+- struct rhlist_head nat_bysource;
++ struct hlist_node nat_bysource;
+ #endif
+ /* all members below initialized via memset */
+ u8 __nfct_init_offset[0];
+--- a/include/net/netfilter/nf_nat.h
++++ b/include/net/netfilter/nf_nat.h
+@@ -1,6 +1,5 @@
+ #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>
+--- a/net/netfilter/nf_nat_core.c
++++ b/net/netfilter/nf_nat_core.c
+@@ -30,19 +30,17 @@
+ #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;
+
+-struct nf_nat_conn_key {
+- const struct net *net;
+- const struct nf_conntrack_tuple *tuple;
+- const struct nf_conntrack_zone *zone;
+-};
+-
+-static struct rhltable nf_nat_bysource_table;
++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;
+
+ inline const struct nf_nat_l3proto *
+ __nf_nat_l3proto_find(u8 family)
+@@ -121,17 +119,19 @@ int nf_xfrm_me_harder(struct net *net, s
+ EXPORT_SYMBOL(nf_xfrm_me_harder);
+ #endif /* CONFIG_XFRM */
+
+-static u32 nf_nat_bysource_hash(const void *data, u32 len, u32 seed)
++/* 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)
+ {
+- const struct nf_conntrack_tuple *t;
+- const struct nf_conn *ct = data;
++ unsigned int hash;
++
++ get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd));
+
+- 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));
+
+- seed ^= net_hash_mix(nf_ct_net(ct));
+- return jhash2((const u32 *)&t->src, sizeof(t->src) / sizeof(u32),
+- t->dst.protonum ^ seed);
++ return reciprocal_scale(hash, nf_nat_htable_size);
+ }
+
+ /* Is this tuple already taken? (not by us) */
+@@ -187,28 +187,6 @@ 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;
+-
+- if (!same_src(ct, key->tuple) ||
+- !net_eq(nf_ct_net(ct), key->net) ||
+- !nf_ct_zone_equal(ct, key->zone, IP_CT_DIR_ORIGINAL))
+- return 1;
+-
+- return 0;
+-}
+-
+-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,
+-};
+-
+ /* Only called for SRC manip */
+ static int
+ find_appropriate_src(struct net *net,
+@@ -219,26 +197,22 @@ 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
+- };
+- struct rhlist_head *hl, *h;
+-
+- hl = rhltable_lookup(&nf_nat_bysource_table, &key,
+- nf_nat_bysource_params);
+
+- rhl_for_each_entry_rcu(ct, h, hl, nat_bysource) {
+- nf_ct_invert_tuplepr(result,
+- &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
+- result->dst = tuple->dst;
++ 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;
++ if (in_range(l3proto, l4proto, result, range))
++ return 1;
++ }
+ }
+-
+ return 0;
+ }
+
+@@ -411,6 +385,7 @@ 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;
+
+@@ -452,19 +427,16 @@ nf_nat_setup_info(struct nf_conn *ct,
+ }
+
+ if (maniptype == NF_NAT_MANIP_SRC) {
+- struct nf_nat_conn_key key = {
+- .net = nf_ct_net(ct),
+- .tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
+- .zone = nf_ct_zone(ct),
+- };
+- int err;
+-
+- err = rhltable_insert_key(&nf_nat_bysource_table,
+- &key,
+- &ct->nat_bysource,
+- nf_nat_bysource_params);
+- if (err)
+- return NF_DROP;
++ unsigned int srchash;
++
++ 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);
+ }
+
+ /* It's done. */
+@@ -578,9 +550,10 @@ static int nf_nat_proto_clean(struct nf_
+ * Else, when the conntrack is destoyed, nf_nat_cleanup_conntrack()
+ * will delete entry from already-freed table.
+ */
++ spin_lock_bh(&nf_nat_lock);
++ hlist_del_rcu(&ct->nat_bysource);
+ ct->status &= ~IPS_NAT_DONE_MASK;
+- rhltable_remove(&nf_nat_bysource_table, &ct->nat_bysource,
+- nf_nat_bysource_params);
++ spin_unlock_bh(&nf_nat_lock);
+
+ /* don't delete conntrack. Although that would make things a lot
+ * simpler, we'd end up flushing all conntracks on nat rmmod.
+@@ -710,8 +683,11 @@ static void nf_nat_cleanup_conntrack(str
+ if (!nat)
+ return;
+
+- rhltable_remove(&nf_nat_bysource_table, &ct->nat_bysource,
+- nf_nat_bysource_params);
++ 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);
+ }
+
+ static struct nf_ct_ext_type nat_extend __read_mostly = {
+@@ -846,13 +822,16 @@ static int __init nf_nat_init(void)
+ {
+ int ret;
+
+- ret = rhltable_init(&nf_nat_bysource_table, &nf_nat_bysource_params);
+- if (ret)
+- return 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 = nf_ct_extend_register(&nat_extend);
+ if (ret < 0) {
+- rhltable_destroy(&nf_nat_bysource_table);
++ nf_ct_free_hashtable(nf_nat_bysource, nf_nat_htable_size);
+ printk(KERN_ERR "nf_nat_core: Unable to register extension\n");
+ return ret;
+ }
+@@ -876,7 +855,7 @@ static int __init nf_nat_init(void)
+ return 0;
+
+ cleanup_extend:
+- rhltable_destroy(&nf_nat_bysource_table);
++ nf_ct_free_hashtable(nf_nat_bysource, nf_nat_htable_size);
+ nf_ct_extend_unregister(&nat_extend);
+ return ret;
+ }
+@@ -896,8 +875,8 @@ static void __exit nf_nat_cleanup(void)
+
+ for (i = 0; i < NFPROTO_NUMPROTO; i++)
+ kfree(nf_nat_l4protos[i]);
+-
+- rhltable_destroy(&nf_nat_bysource_table);
++ synchronize_net();
++ nf_ct_free_hashtable(nf_nat_bysource, nf_nat_htable_size);
+ }
+
+ MODULE_LICENSE("GPL");
projects / thirdparty / kernel / stable-queue.git / commitdiff
