From a71c085562bcc99e8b711cab4222bff1f6e955da Mon Sep 17 00:00:00 2001
From: Patrick McHardy <kaber@trash.net>
Date: Sat, 7 Jul 2007 22:33:47 -0700
Subject: [PATCH] [NETFILTER]: nf_conntrack: use hashtable for expectations
Currently all expectations are kept on a global list that
- needs to be searched for every new conncetion
- needs to be walked for evicting expectations when a master connection
has reached its limit
- needs to be walked on connection destruction for connections that
have open expectations
This is obviously not good, especially when considering helpers like
H.323 that register *lots* of expectations and can set up permanent
expectations, but it also allows for an easy DoS against firewalls
using connection tracking helpers.
Use a hashtable for expectations to avoid incurring the search overhead
for every new connection. The default hash size is 1/256 of the conntrack
hash table size, this can be overriden using a module parameter.
This patch only introduces the hash table for expectation lookups and
keeps other users to reduce the noise, the following patches will get
rid of it completely.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/net/netfilter/nf_conntrack_core.h | 1 -
include/net/netfilter/nf_conntrack_expect.h | 5 ++
net/netfilter/nf_conntrack_expect.c | 72 +++++++++++++++++++--
3 files changed, 71 insertions(+), 7 deletions(-)
diff --git a/include/net/netfilter/nf_conntrack_core.h b/include/net/netfilter/nf_conntrack_core.h
index a18f79c80db8..4056f5f08da1 100644
--- a/include/net/netfilter/nf_conntrack_core.h
+++ b/include/net/netfilter/nf_conntrack_core.h
@@ -84,7 +84,6 @@ print_tuple(struct seq_file *s, const struct nf_conntrack_tuple *tuple,
struct nf_conntrack_l4proto *proto);
extern struct hlist_head *nf_conntrack_hash;
-extern struct list_head nf_ct_expect_list;
extern rwlock_t nf_conntrack_lock ;
extern struct hlist_head unconfirmed;
diff --git a/include/net/netfilter/nf_conntrack_expect.h b/include/net/netfilter/nf_conntrack_expect.h
index cf6a619664e8..424d4bdb9848 100644
--- a/include/net/netfilter/nf_conntrack_expect.h
+++ b/include/net/netfilter/nf_conntrack_expect.h
@@ -7,12 +7,17 @@
#include <net/netfilter/nf_conntrack.h>
extern struct list_head nf_ct_expect_list;
+extern struct hlist_head *nf_ct_expect_hash;
+extern unsigned int nf_ct_expect_hsize;
struct nf_conntrack_expect
{
/* Internal linked list (global expectation list) */
struct list_head list;
+ /* Hash member */
+ struct hlist_node hnode;
+
/* We expect this tuple, with the following mask */
struct nf_conntrack_tuple tuple;
struct nf_conntrack_tuple_mask mask;
diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c
index ad197bccc7ca..0696f87aaef1 100644
--- a/net/netfilter/nf_conntrack_expect.c
+++ b/net/netfilter/nf_conntrack_expect.c
@@ -19,6 +19,7 @@
#include <linux/err.h>
#include <linux/percpu.h>
#include <linux/kernel.h>
+#include <linux/jhash.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_core.h>
@@ -29,6 +30,17 @@
LIST_HEAD(nf_ct_expect_list);
EXPORT_SYMBOL_GPL(nf_ct_expect_list);
+struct hlist_head *nf_ct_expect_hash __read_mostly;
+EXPORT_SYMBOL_GPL(nf_ct_expect_hash);
+
+unsigned int nf_ct_expect_hsize __read_mostly;
+EXPORT_SYMBOL_GPL(nf_ct_expect_hsize);
+
+static unsigned int nf_ct_expect_hash_rnd __read_mostly;
+static unsigned int nf_ct_expect_count;
+static int nf_ct_expect_hash_rnd_initted __read_mostly;
+static int nf_ct_expect_vmalloc;
+
static struct kmem_cache *nf_ct_expect_cachep __read_mostly;
static unsigned int nf_ct_expect_next_id;
@@ -41,6 +53,9 @@ void nf_ct_unlink_expect(struct nf_conntrack_expect *exp)
NF_CT_ASSERT(!timer_pending(&exp->timeout));
list_del(&exp->list);
+ hlist_del(&exp->hnode);
+ nf_ct_expect_count--;
+
NF_CT_STAT_INC(expect_delete);
master_help->expecting--;
nf_ct_expect_put(exp);
@@ -57,12 +72,31 @@ static void nf_ct_expectation_timed_out(unsigned long ul_expect)
nf_ct_expect_put(exp);
}
+static unsigned int nf_ct_expect_dst_hash(const struct nf_conntrack_tuple *tuple)
+{
+ if (unlikely(!nf_ct_expect_hash_rnd_initted)) {
+ get_random_bytes(&nf_ct_expect_hash_rnd, 4);
+ nf_ct_expect_hash_rnd_initted = 1;
+ }
+
+ return jhash2(tuple->dst.u3.all, ARRAY_SIZE(tuple->dst.u3.all),
+ (((tuple->dst.protonum ^ tuple->src.l3num) << 16) |
+ tuple->dst.u.all) ^ nf_ct_expect_hash_rnd) %
+ nf_ct_expect_hsize;
+}
+
struct nf_conntrack_expect *
__nf_ct_expect_find(const struct nf_conntrack_tuple *tuple)
{
struct nf_conntrack_expect *i;
+ struct hlist_node *n;
+ unsigned int h;
+
+ if (!nf_ct_expect_count)
+ return NULL;
- list_for_each_entry(i, &nf_ct_expect_list, list) {
+ h = nf_ct_expect_dst_hash(tuple);
+ hlist_for_each_entry(i, n, &nf_ct_expect_hash[h], hnode) {
if (nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask))
return i;
}
@@ -252,10 +286,14 @@ EXPORT_SYMBOL_GPL(nf_ct_expect_put);
static void nf_ct_expect_insert(struct nf_conntrack_expect *exp)
{
struct nf_conn_help *master_help = nfct_help(exp->master);
+ unsigned int h = nf_ct_expect_dst_hash(&exp->tuple);
atomic_inc(&exp->use);
master_help->expecting++;
+
list_add(&exp->list, &nf_ct_expect_list);
+ hlist_add_head(&exp->hnode, &nf_ct_expect_hash[h]);
+ nf_ct_expect_count++;
setup_timer(&exp->timeout, nf_ct_expectation_timed_out,
(unsigned long)exp);
@@ -300,6 +338,8 @@ int nf_ct_expect_related(struct nf_conntrack_expect *expect)
struct nf_conntrack_expect *i;
struct nf_conn *master = expect->master;
struct nf_conn_help *master_help = nfct_help(master);
+ struct hlist_node *n;
+ unsigned int h;
int ret;
NF_CT_ASSERT(master_help);
@@ -309,7 +349,8 @@ int nf_ct_expect_related(struct nf_conntrack_expect *expect)
ret = -ESHUTDOWN;
goto out;
}
- list_for_each_entry(i, &nf_ct_expect_list, list) {
+ h = nf_ct_expect_dst_hash(&expect->tuple);
+ hlist_for_each_entry(i, n, &nf_ct_expect_hash[h], hnode) {
if (expect_matches(i, expect)) {
/* Refresh timer: if it's dying, ignore.. */
if (refresh_timer(i)) {
@@ -433,24 +474,41 @@ static void exp_proc_remove(void)
#endif /* CONFIG_PROC_FS */
}
+module_param_named(expect_hashsize, nf_ct_expect_hsize, uint, 0600);
+
int __init nf_conntrack_expect_init(void)
{
- int err;
+ int err = -ENOMEM;
+
+ if (!nf_ct_expect_hsize) {
+ nf_ct_expect_hsize = nf_conntrack_htable_size / 256;
+ if (!nf_ct_expect_hsize)
+ nf_ct_expect_hsize = 1;
+ }
+
+ nf_ct_expect_hash = nf_ct_alloc_hashtable(&nf_ct_expect_hsize,
+ &nf_ct_expect_vmalloc);
+ if (nf_ct_expect_hash == NULL)
+ goto err1;
nf_ct_expect_cachep = kmem_cache_create("nf_conntrack_expect",
sizeof(struct nf_conntrack_expect),
0, 0, NULL, NULL);
if (!nf_ct_expect_cachep)
- return -ENOMEM;
+ goto err2;
err = exp_proc_init();
if (err < 0)
- goto err1;
+ goto err3;
return 0;
-err1:
+err3:
+ nf_ct_free_hashtable(nf_ct_expect_hash, nf_ct_expect_vmalloc,
+ nf_ct_expect_hsize);
+err2:
kmem_cache_destroy(nf_ct_expect_cachep);
+err1:
return err;
}
@@ -458,4 +516,6 @@ void nf_conntrack_expect_fini(void)
{
exp_proc_remove();
kmem_cache_destroy(nf_ct_expect_cachep);
+ nf_ct_free_hashtable(nf_ct_expect_hash, nf_ct_expect_vmalloc,
+ nf_ct_expect_hsize);
}
--
2.20.1