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>
6 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
13 #include <linux/types.h>
14 #include <linux/netfilter.h>
15 #include <linux/module.h>
16 #include <linux/skbuff.h>
17 #include <linux/vmalloc.h>
18 #include <linux/stddef.h>
19 #include <linux/random.h>
20 #include <linux/err.h>
21 #include <linux/kernel.h>
22 #include <linux/netdevice.h>
23 #include <linux/rculist.h>
24 #include <linux/rtnetlink.h>
26 #include <net/netfilter/nf_conntrack.h>
27 #include <net/netfilter/nf_conntrack_l3proto.h>
28 #include <net/netfilter/nf_conntrack_l4proto.h>
29 #include <net/netfilter/nf_conntrack_helper.h>
30 #include <net/netfilter/nf_conntrack_core.h>
31 #include <net/netfilter/nf_conntrack_extend.h>
32 #include <net/netfilter/nf_log.h>
34 static DEFINE_MUTEX(nf_ct_helper_mutex);
35 struct hlist_head *nf_ct_helper_hash __read_mostly;
36 EXPORT_SYMBOL_GPL(nf_ct_helper_hash);
37 unsigned int nf_ct_helper_hsize __read_mostly;
38 EXPORT_SYMBOL_GPL(nf_ct_helper_hsize);
39 static unsigned int nf_ct_helper_count __read_mostly;
41 static bool nf_ct_auto_assign_helper __read_mostly = false;
42 module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644);
43 MODULE_PARM_DESC(nf_conntrack_helper,
44 "Enable automatic conntrack helper assignment (default 0)");
47 static struct ctl_table helper_sysctl_table[] = {
49 .procname = "nf_conntrack_helper",
50 .data = &init_net.ct.sysctl_auto_assign_helper,
51 .maxlen = sizeof(unsigned int),
53 .proc_handler = proc_dointvec,
58 static int nf_conntrack_helper_init_sysctl(struct net *net)
60 struct ctl_table *table;
62 table = kmemdup(helper_sysctl_table, sizeof(helper_sysctl_table),
67 table[0].data = &net->ct.sysctl_auto_assign_helper;
69 /* Don't export sysctls to unprivileged users */
70 if (net->user_ns != &init_user_ns)
71 table[0].procname = NULL;
73 net->ct.helper_sysctl_header =
74 register_net_sysctl(net, "net/netfilter", table);
76 if (!net->ct.helper_sysctl_header) {
77 pr_err("nf_conntrack_helper: can't register to sysctl.\n");
88 static void nf_conntrack_helper_fini_sysctl(struct net *net)
90 struct ctl_table *table;
92 table = net->ct.helper_sysctl_header->ctl_table_arg;
93 unregister_net_sysctl_table(net->ct.helper_sysctl_header);
97 static int nf_conntrack_helper_init_sysctl(struct net *net)
102 static void nf_conntrack_helper_fini_sysctl(struct net *net)
105 #endif /* CONFIG_SYSCTL */
107 /* Stupid hash, but collision free for the default registrations of the
108 * helpers currently in the kernel. */
109 static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
111 return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^
112 (__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
115 static struct nf_conntrack_helper *
116 __nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
118 struct nf_conntrack_helper *helper;
119 struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
122 if (!nf_ct_helper_count)
125 h = helper_hash(tuple);
126 hlist_for_each_entry_rcu(helper, &nf_ct_helper_hash[h], hnode) {
127 if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
133 struct nf_conntrack_helper *
134 __nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
136 struct nf_conntrack_helper *h;
139 for (i = 0; i < nf_ct_helper_hsize; i++) {
140 hlist_for_each_entry_rcu(h, &nf_ct_helper_hash[i], hnode) {
141 if (!strcmp(h->name, name) &&
142 h->tuple.src.l3num == l3num &&
143 h->tuple.dst.protonum == protonum)
149 EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
151 struct nf_conntrack_helper *
152 nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
154 struct nf_conntrack_helper *h;
156 h = __nf_conntrack_helper_find(name, l3num, protonum);
157 #ifdef CONFIG_MODULES
159 if (request_module("nfct-helper-%s", name) == 0)
160 h = __nf_conntrack_helper_find(name, l3num, protonum);
163 if (h != NULL && !try_module_get(h->me))
168 EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
170 struct nf_conn_help *
171 nf_ct_helper_ext_add(struct nf_conn *ct,
172 struct nf_conntrack_helper *helper, gfp_t gfp)
174 struct nf_conn_help *help;
176 help = nf_ct_ext_add_length(ct, NF_CT_EXT_HELPER,
177 helper->data_len, gfp);
179 INIT_HLIST_HEAD(&help->expectations);
181 pr_debug("failed to add helper extension area");
184 EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
186 int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
189 struct nf_conntrack_helper *helper = NULL;
190 struct nf_conn_help *help;
191 struct net *net = nf_ct_net(ct);
194 /* We already got a helper explicitly attached. The function
195 * nf_conntrack_alter_reply - in case NAT is in use - asks for looking
196 * the helper up again. Since now the user is in full control of
197 * making consistent helper configurations, skip this automatic
198 * re-lookup, otherwise we'll lose the helper.
200 if (test_bit(IPS_HELPER_BIT, &ct->status))
204 help = nfct_help(tmpl);
206 helper = help->helper;
207 set_bit(IPS_HELPER_BIT, &ct->status);
211 help = nfct_help(ct);
212 if (net->ct.sysctl_auto_assign_helper && helper == NULL) {
213 helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
214 if (unlikely(!net->ct.auto_assign_helper_warned && helper)) {
215 pr_info("nf_conntrack: automatic helper "
216 "assignment is deprecated and it will "
217 "be removed soon. Use the iptables CT target "
218 "to attach helpers instead.\n");
219 net->ct.auto_assign_helper_warned = true;
223 if (helper == NULL) {
225 RCU_INIT_POINTER(help->helper, NULL);
230 help = nf_ct_helper_ext_add(ct, helper, flags);
236 /* We only allow helper re-assignment of the same sort since
237 * we cannot reallocate the helper extension area.
239 struct nf_conntrack_helper *tmp = rcu_dereference(help->helper);
241 if (tmp && tmp->help != helper->help) {
242 RCU_INIT_POINTER(help->helper, NULL);
247 rcu_assign_pointer(help->helper, helper);
251 EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
253 /* appropriate ct lock protecting must be taken by caller */
254 static inline int unhelp(struct nf_conntrack_tuple_hash *i,
255 const struct nf_conntrack_helper *me)
257 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
258 struct nf_conn_help *help = nfct_help(ct);
260 if (help && rcu_dereference_raw(help->helper) == me) {
261 nf_conntrack_event(IPCT_HELPER, ct);
262 RCU_INIT_POINTER(help->helper, NULL);
267 void nf_ct_helper_destroy(struct nf_conn *ct)
269 struct nf_conn_help *help = nfct_help(ct);
270 struct nf_conntrack_helper *helper;
274 helper = rcu_dereference(help->helper);
275 if (helper && helper->destroy)
281 static LIST_HEAD(nf_ct_helper_expectfn_list);
283 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
285 spin_lock_bh(&nf_conntrack_expect_lock);
286 list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
287 spin_unlock_bh(&nf_conntrack_expect_lock);
289 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);
291 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
293 spin_lock_bh(&nf_conntrack_expect_lock);
294 list_del_rcu(&n->head);
295 spin_unlock_bh(&nf_conntrack_expect_lock);
297 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
299 struct nf_ct_helper_expectfn *
300 nf_ct_helper_expectfn_find_by_name(const char *name)
302 struct nf_ct_helper_expectfn *cur;
306 list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
307 if (!strcmp(cur->name, name)) {
313 return found ? cur : NULL;
315 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);
317 struct nf_ct_helper_expectfn *
318 nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
320 struct nf_ct_helper_expectfn *cur;
324 list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
325 if (cur->expectfn == symbol) {
331 return found ? cur : NULL;
333 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
336 void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
337 const char *fmt, ...)
339 const struct nf_conn_help *help;
340 const struct nf_conntrack_helper *helper;
341 struct va_format vaf;
349 /* Called from the helper function, this call never fails */
350 help = nfct_help(ct);
352 /* rcu_read_lock()ed by nf_hook_slow */
353 helper = rcu_dereference(help->helper);
355 nf_log_packet(nf_ct_net(ct), nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL,
356 "nf_ct_%s: dropping packet: %pV ", helper->name, &vaf);
360 EXPORT_SYMBOL_GPL(nf_ct_helper_log);
362 int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
364 struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
365 unsigned int h = helper_hash(&me->tuple);
366 struct nf_conntrack_helper *cur;
369 BUG_ON(me->expect_policy == NULL);
370 BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
371 BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
373 mutex_lock(&nf_ct_helper_mutex);
374 hlist_for_each_entry(cur, &nf_ct_helper_hash[h], hnode) {
375 if (nf_ct_tuple_src_mask_cmp(&cur->tuple, &me->tuple, &mask)) {
380 hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
381 nf_ct_helper_count++;
383 mutex_unlock(&nf_ct_helper_mutex);
386 EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
388 static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
391 struct nf_conntrack_tuple_hash *h;
392 const struct hlist_nulls_node *nn;
395 /* Get rid of expecteds, set helpers to NULL. */
396 for_each_possible_cpu(cpu) {
397 struct ct_pcpu *pcpu = per_cpu_ptr(net->ct.pcpu_lists, cpu);
399 spin_lock_bh(&pcpu->lock);
400 hlist_nulls_for_each_entry(h, nn, &pcpu->unconfirmed, hnnode)
402 spin_unlock_bh(&pcpu->lock);
406 void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
408 struct nf_conntrack_tuple_hash *h;
409 struct nf_conntrack_expect *exp;
410 const struct hlist_node *next;
411 const struct hlist_nulls_node *nn;
412 unsigned int last_hsize;
417 mutex_lock(&nf_ct_helper_mutex);
418 hlist_del_rcu(&me->hnode);
419 nf_ct_helper_count--;
420 mutex_unlock(&nf_ct_helper_mutex);
422 /* Make sure every nothing is still using the helper unless its a
423 * connection in the hash.
427 /* Get rid of expectations */
428 spin_lock_bh(&nf_conntrack_expect_lock);
429 for (i = 0; i < nf_ct_expect_hsize; i++) {
430 hlist_for_each_entry_safe(exp, next,
431 &nf_ct_expect_hash[i], hnode) {
432 struct nf_conn_help *help = nfct_help(exp->master);
433 if ((rcu_dereference_protected(
435 lockdep_is_held(&nf_conntrack_expect_lock)
436 ) == me || exp->helper == me) &&
437 del_timer(&exp->timeout)) {
438 nf_ct_unlink_expect(exp);
439 nf_ct_expect_put(exp);
443 spin_unlock_bh(&nf_conntrack_expect_lock);
447 __nf_conntrack_helper_unregister(me, net);
452 last_hsize = nf_conntrack_htable_size;
453 for (i = 0; i < last_hsize; i++) {
454 lock = &nf_conntrack_locks[i % CONNTRACK_LOCKS];
455 nf_conntrack_lock(lock);
456 if (last_hsize != nf_conntrack_htable_size) {
460 hlist_nulls_for_each_entry(h, nn, &nf_conntrack_hash[i], hnnode)
466 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
468 void nf_ct_helper_init(struct nf_conntrack_helper *helper,
469 u16 l3num, u16 protonum, const char *name,
470 u16 default_port, u16 spec_port, u32 id,
471 const struct nf_conntrack_expect_policy *exp_pol,
472 u32 expect_class_max, u32 data_len,
473 int (*help)(struct sk_buff *skb, unsigned int protoff,
475 enum ip_conntrack_info ctinfo),
476 int (*from_nlattr)(struct nlattr *attr,
478 struct module *module)
480 helper->tuple.src.l3num = l3num;
481 helper->tuple.dst.protonum = protonum;
482 helper->tuple.src.u.all = htons(spec_port);
483 helper->expect_policy = exp_pol;
484 helper->expect_class_max = expect_class_max;
485 helper->data_len = data_len;
487 helper->from_nlattr = from_nlattr;
490 if (spec_port == default_port)
491 snprintf(helper->name, sizeof(helper->name), "%s", name);
493 snprintf(helper->name, sizeof(helper->name), "%s-%u", name, id);
495 EXPORT_SYMBOL_GPL(nf_ct_helper_init);
497 int nf_conntrack_helpers_register(struct nf_conntrack_helper *helper,
503 for (i = 0; i < n; i++) {
504 err = nf_conntrack_helper_register(&helper[i]);
512 nf_conntrack_helpers_unregister(helper, i);
515 EXPORT_SYMBOL_GPL(nf_conntrack_helpers_register);
517 void nf_conntrack_helpers_unregister(struct nf_conntrack_helper *helper,
521 nf_conntrack_helper_unregister(&helper[n]);
523 EXPORT_SYMBOL_GPL(nf_conntrack_helpers_unregister);
525 static struct nf_ct_ext_type helper_extend __read_mostly = {
526 .len = sizeof(struct nf_conn_help),
527 .align = __alignof__(struct nf_conn_help),
528 .id = NF_CT_EXT_HELPER,
531 int nf_conntrack_helper_pernet_init(struct net *net)
533 net->ct.auto_assign_helper_warned = false;
534 net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
535 return nf_conntrack_helper_init_sysctl(net);
538 void nf_conntrack_helper_pernet_fini(struct net *net)
540 nf_conntrack_helper_fini_sysctl(net);
543 int nf_conntrack_helper_init(void)
546 nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
548 nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
549 if (!nf_ct_helper_hash)
552 ret = nf_ct_extend_register(&helper_extend);
554 pr_err("nf_ct_helper: Unable to register helper extension.\n");
560 nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
564 void nf_conntrack_helper_fini(void)
566 nf_ct_extend_unregister(&helper_extend);
567 nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);