1 /* Helper handling for netfilter. */
3 /* (C) 1999-2001 Paul `Rusty' Russell
4 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
5 * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
12 #include <linux/types.h>
13 #include <linux/netfilter.h>
14 #include <linux/module.h>
15 #include <linux/skbuff.h>
16 #include <linux/vmalloc.h>
17 #include <linux/stddef.h>
18 #include <linux/random.h>
19 #include <linux/err.h>
20 #include <linux/kernel.h>
21 #include <linux/netdevice.h>
22 #include <linux/rculist.h>
23 #include <linux/rtnetlink.h>
25 #include <net/netfilter/nf_conntrack.h>
26 #include <net/netfilter/nf_conntrack_l3proto.h>
27 #include <net/netfilter/nf_conntrack_l4proto.h>
28 #include <net/netfilter/nf_conntrack_helper.h>
29 #include <net/netfilter/nf_conntrack_core.h>
30 #include <net/netfilter/nf_conntrack_extend.h>
32 static DEFINE_MUTEX(nf_ct_helper_mutex);
33 static struct hlist_head *nf_ct_helper_hash __read_mostly;
34 static unsigned int nf_ct_helper_hsize __read_mostly;
35 static unsigned int nf_ct_helper_count __read_mostly;
37 static bool nf_ct_auto_assign_helper __read_mostly = true;
38 module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644);
39 MODULE_PARM_DESC(nf_conntrack_helper,
40 "Enable automatic conntrack helper assignment (default 1)");
43 static struct ctl_table helper_sysctl_table[] = {
45 .procname = "nf_conntrack_helper",
46 .data = &init_net.ct.sysctl_auto_assign_helper,
47 .maxlen = sizeof(unsigned int),
49 .proc_handler = proc_dointvec,
54 static int nf_conntrack_helper_init_sysctl(struct net *net)
56 struct ctl_table *table;
58 table = kmemdup(helper_sysctl_table, sizeof(helper_sysctl_table),
63 table[0].data = &net->ct.sysctl_auto_assign_helper;
65 net->ct.helper_sysctl_header =
66 register_net_sysctl(net, "net/netfilter", table);
68 if (!net->ct.helper_sysctl_header) {
69 pr_err("nf_conntrack_helper: can't register to sysctl.\n");
80 static void nf_conntrack_helper_fini_sysctl(struct net *net)
82 struct ctl_table *table;
84 table = net->ct.helper_sysctl_header->ctl_table_arg;
85 unregister_net_sysctl_table(net->ct.helper_sysctl_header);
89 static int nf_conntrack_helper_init_sysctl(struct net *net)
94 static void nf_conntrack_helper_fini_sysctl(struct net *net)
97 #endif /* CONFIG_SYSCTL */
99 /* Stupid hash, but collision free for the default registrations of the
100 * helpers currently in the kernel. */
101 static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
103 return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^
104 (__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
107 static struct nf_conntrack_helper *
108 __nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
110 struct nf_conntrack_helper *helper;
111 struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
112 struct hlist_node *n;
115 if (!nf_ct_helper_count)
118 h = helper_hash(tuple);
119 hlist_for_each_entry_rcu(helper, n, &nf_ct_helper_hash[h], hnode) {
120 if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
126 struct nf_conntrack_helper *
127 __nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
129 struct nf_conntrack_helper *h;
130 struct hlist_node *n;
133 for (i = 0; i < nf_ct_helper_hsize; i++) {
134 hlist_for_each_entry_rcu(h, n, &nf_ct_helper_hash[i], hnode) {
135 if (!strcmp(h->name, name) &&
136 h->tuple.src.l3num == l3num &&
137 h->tuple.dst.protonum == protonum)
143 EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
145 struct nf_conntrack_helper *
146 nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
148 struct nf_conntrack_helper *h;
150 h = __nf_conntrack_helper_find(name, l3num, protonum);
151 #ifdef CONFIG_MODULES
153 if (request_module("nfct-helper-%s", name) == 0)
154 h = __nf_conntrack_helper_find(name, l3num, protonum);
157 if (h != NULL && !try_module_get(h->me))
162 EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
164 struct nf_conn_help *
165 nf_ct_helper_ext_add(struct nf_conn *ct,
166 struct nf_conntrack_helper *helper, gfp_t gfp)
168 struct nf_conn_help *help;
170 help = nf_ct_ext_add_length(ct, NF_CT_EXT_HELPER,
171 helper->data_len, gfp);
173 INIT_HLIST_HEAD(&help->expectations);
175 pr_debug("failed to add helper extension area");
178 EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
180 int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
183 struct nf_conntrack_helper *helper = NULL;
184 struct nf_conn_help *help;
185 struct net *net = nf_ct_net(ct);
188 /* We already got a helper explicitly attached. The function
189 * nf_conntrack_alter_reply - in case NAT is in use - asks for looking
190 * the helper up again. Since now the user is in full control of
191 * making consistent helper configurations, skip this automatic
192 * re-lookup, otherwise we'll lose the helper.
194 if (test_bit(IPS_HELPER_BIT, &ct->status))
198 help = nfct_help(tmpl);
200 helper = help->helper;
201 set_bit(IPS_HELPER_BIT, &ct->status);
205 help = nfct_help(ct);
206 if (net->ct.sysctl_auto_assign_helper && helper == NULL) {
207 helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
208 if (unlikely(!net->ct.auto_assign_helper_warned && helper)) {
209 pr_info("nf_conntrack: automatic helper "
210 "assignment is deprecated and it will "
211 "be removed soon. Use the iptables CT target "
212 "to attach helpers instead.\n");
213 net->ct.auto_assign_helper_warned = true;
217 if (helper == NULL) {
219 RCU_INIT_POINTER(help->helper, NULL);
224 help = nf_ct_helper_ext_add(ct, helper, flags);
230 memset(help->data, 0, helper->data_len);
233 rcu_assign_pointer(help->helper, helper);
237 EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
239 static inline int unhelp(struct nf_conntrack_tuple_hash *i,
240 const struct nf_conntrack_helper *me)
242 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
243 struct nf_conn_help *help = nfct_help(ct);
245 if (help && rcu_dereference_protected(
247 lockdep_is_held(&nf_conntrack_lock)
249 nf_conntrack_event(IPCT_HELPER, ct);
250 RCU_INIT_POINTER(help->helper, NULL);
255 void nf_ct_helper_destroy(struct nf_conn *ct)
257 struct nf_conn_help *help = nfct_help(ct);
258 struct nf_conntrack_helper *helper;
262 helper = rcu_dereference(help->helper);
263 if (helper && helper->destroy)
269 static LIST_HEAD(nf_ct_helper_expectfn_list);
271 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
273 spin_lock_bh(&nf_conntrack_lock);
274 list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
275 spin_unlock_bh(&nf_conntrack_lock);
277 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);
279 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
281 spin_lock_bh(&nf_conntrack_lock);
282 list_del_rcu(&n->head);
283 spin_unlock_bh(&nf_conntrack_lock);
285 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
287 struct nf_ct_helper_expectfn *
288 nf_ct_helper_expectfn_find_by_name(const char *name)
290 struct nf_ct_helper_expectfn *cur;
294 list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
295 if (!strcmp(cur->name, name)) {
301 return found ? cur : NULL;
303 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);
305 struct nf_ct_helper_expectfn *
306 nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
308 struct nf_ct_helper_expectfn *cur;
312 list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
313 if (cur->expectfn == symbol) {
319 return found ? cur : NULL;
321 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
323 int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
325 unsigned int h = helper_hash(&me->tuple);
327 BUG_ON(me->expect_policy == NULL);
328 BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
329 BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
331 mutex_lock(&nf_ct_helper_mutex);
332 hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
333 nf_ct_helper_count++;
334 mutex_unlock(&nf_ct_helper_mutex);
338 EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
340 static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
343 struct nf_conntrack_tuple_hash *h;
344 struct nf_conntrack_expect *exp;
345 const struct hlist_node *n, *next;
346 const struct hlist_nulls_node *nn;
349 /* Get rid of expectations */
350 for (i = 0; i < nf_ct_expect_hsize; i++) {
351 hlist_for_each_entry_safe(exp, n, next,
352 &net->ct.expect_hash[i], hnode) {
353 struct nf_conn_help *help = nfct_help(exp->master);
354 if ((rcu_dereference_protected(
356 lockdep_is_held(&nf_conntrack_lock)
357 ) == me || exp->helper == me) &&
358 del_timer(&exp->timeout)) {
359 nf_ct_unlink_expect(exp);
360 nf_ct_expect_put(exp);
365 /* Get rid of expecteds, set helpers to NULL. */
366 hlist_nulls_for_each_entry(h, nn, &net->ct.unconfirmed, hnnode)
368 for (i = 0; i < net->ct.htable_size; i++) {
369 hlist_nulls_for_each_entry(h, nn, &net->ct.hash[i], hnnode)
374 void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
378 mutex_lock(&nf_ct_helper_mutex);
379 hlist_del_rcu(&me->hnode);
380 nf_ct_helper_count--;
381 mutex_unlock(&nf_ct_helper_mutex);
383 /* Make sure every nothing is still using the helper unless its a
384 * connection in the hash.
389 spin_lock_bh(&nf_conntrack_lock);
391 __nf_conntrack_helper_unregister(me, net);
392 spin_unlock_bh(&nf_conntrack_lock);
395 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
397 static struct nf_ct_ext_type helper_extend __read_mostly = {
398 .len = sizeof(struct nf_conn_help),
399 .align = __alignof__(struct nf_conn_help),
400 .id = NF_CT_EXT_HELPER,
403 int nf_conntrack_helper_init(struct net *net)
407 net->ct.auto_assign_helper_warned = false;
408 net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
410 if (net_eq(net, &init_net)) {
411 nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
413 nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
414 if (!nf_ct_helper_hash)
417 err = nf_ct_extend_register(&helper_extend);
422 err = nf_conntrack_helper_init_sysctl(net);
429 if (net_eq(net, &init_net))
430 nf_ct_extend_unregister(&helper_extend);
432 nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
436 void nf_conntrack_helper_fini(struct net *net)
438 nf_conntrack_helper_fini_sysctl(net);
439 if (net_eq(net, &init_net)) {
440 nf_ct_extend_unregister(&helper_extend);
441 nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);