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 --- include/net/netfilter/nf_conntrack.h | 3 +- include/net/netfilter/nf_nat.h | 1 - net/netfilter/nf_nat_core.c | 134 +++++++++++++++-------------------- 3 files changed, 57 insertions(+), 81 deletions(-)

diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h index d9d52c020a70..9ae819e27940 100644 --- 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]; diff --git a/include/net/netfilter/nf_nat.h b/include/net/netfilter/nf_nat.h index c327a431a6f3..02515f7ed4cc 100644 --- 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> diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c index e9fcb58d4eba..624d6e4dcd5c 100644 --- 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, struct sk_buff *skb, unsigned int family) 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; - - if (in_range(l3proto, l4proto, result, range)) - return 1; + 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; }

@@ -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. */ @@ -572,9 +544,10 @@ static int nf_nat_proto_clean(struct nf_conn *ct, void *data) * 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. @@ -699,9 +672,11 @@ EXPORT_SYMBOL_GPL(nf_nat_l3proto_unregister); /* No one using conntrack by the time this called. */ static void nf_nat_cleanup_conntrack(struct nf_conn *ct) { - if (ct->status & IPS_SRC_NAT_DONE) - rhltable_remove(&nf_nat_bysource_table, &ct->nat_bysource, - nf_nat_bysource_params); + if (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 = { @@ -836,13 +811,16 @@ 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; } @@ -866,7 +844,7 @@ 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; } @@ -886,8 +864,8 @@ 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");