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: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index e5135d8728b4c565d86ec2db8ade5994b150ac65..a08825b7e955cc6da5d5aa0d8e32e5190c53f68c 100644 (file)
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -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;

diff --git a/include/net/netfilter/nf_nat.h b/include/net/netfilter/nf_nat.h
index 02515f7ed4cceceeaa9eb974531e2ec342346d07..c327a431a6f38103598b82182d463dd728f70443 100644 (file)
--- a/include/net/netfilter/nf_nat.h
+++ b/include/net/netfilter/nf_nat.h
@@ -1,5 +1,6 @@
 #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 692534701426cfae8c5f783d9e803180b0bf7c80..de31818417b88a6ebf04ee623d8f34c50bdc0f50 100644 (file)
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -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
+       };
 
-       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;
+       ct = rhashtable_lookup_fast(&nf_nat_bysource_table, &key,
+                                   nf_nat_bysource_params);
+       if (!ct)
+               return 0;
+
+       nf_ct_invert_tuplepr(result,
+                            &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
+       result->dst = tuple->dst;
+
+       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;
-
-               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);
+               int err;
+
+               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");