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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>
25
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>
33
34static DEFINE_MUTEX(nf_ct_helper_mutex);
35struct hlist_head *nf_ct_helper_hash __read_mostly;
36EXPORT_SYMBOL_GPL(nf_ct_helper_hash);
37unsigned int nf_ct_helper_hsize __read_mostly;
38EXPORT_SYMBOL_GPL(nf_ct_helper_hsize);
39static unsigned int nf_ct_helper_count __read_mostly;
40
41static bool nf_ct_auto_assign_helper __read_mostly = false;
42module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644);
43MODULE_PARM_DESC(nf_conntrack_helper,
44 "Enable automatic conntrack helper assignment (default 0)");
45
46#ifdef CONFIG_SYSCTL
47static struct ctl_table helper_sysctl_table[] = {
48 {
49 .procname = "nf_conntrack_helper",
50 .data = &init_net.ct.sysctl_auto_assign_helper,
51 .maxlen = sizeof(unsigned int),
52 .mode = 0644,
53 .proc_handler = proc_dointvec,
54 },
55 {}
56};
57
58static int nf_conntrack_helper_init_sysctl(struct net *net)
59{
60 struct ctl_table *table;
61
62 table = kmemdup(helper_sysctl_table, sizeof(helper_sysctl_table),
63 GFP_KERNEL);
64 if (!table)
65 goto out;
66
67 table[0].data = &net->ct.sysctl_auto_assign_helper;
68
69
70 if (net->user_ns != &init_user_ns)
71 table[0].procname = NULL;
72
73 net->ct.helper_sysctl_header =
74 register_net_sysctl(net, "net/netfilter", table);
75
76 if (!net->ct.helper_sysctl_header) {
77 pr_err("nf_conntrack_helper: can't register to sysctl.\n");
78 goto out_register;
79 }
80 return 0;
81
82out_register:
83 kfree(table);
84out:
85 return -ENOMEM;
86}
87
88static void nf_conntrack_helper_fini_sysctl(struct net *net)
89{
90 struct ctl_table *table;
91
92 table = net->ct.helper_sysctl_header->ctl_table_arg;
93 unregister_net_sysctl_table(net->ct.helper_sysctl_header);
94 kfree(table);
95}
96#else
97static int nf_conntrack_helper_init_sysctl(struct net *net)
98{
99 return 0;
100}
101
102static void nf_conntrack_helper_fini_sysctl(struct net *net)
103{
104}
105#endif
106
107
108
109static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
110{
111 return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^
112 (__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
113}
114
115static struct nf_conntrack_helper *
116__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
117{
118 struct nf_conntrack_helper *helper;
119 struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
120 unsigned int h;
121
122 if (!nf_ct_helper_count)
123 return NULL;
124
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))
128 return helper;
129 }
130 return NULL;
131}
132
133struct nf_conntrack_helper *
134__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
135{
136 struct nf_conntrack_helper *h;
137 unsigned int i;
138
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 continue;
143
144 if (h->tuple.src.l3num != NFPROTO_UNSPEC &&
145 h->tuple.src.l3num != l3num)
146 continue;
147
148 if (h->tuple.dst.protonum == protonum)
149 return h;
150 }
151 }
152 return NULL;
153}
154EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
155
156struct nf_conntrack_helper *
157nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
158{
159 struct nf_conntrack_helper *h;
160
161 h = __nf_conntrack_helper_find(name, l3num, protonum);
162#ifdef CONFIG_MODULES
163 if (h == NULL) {
164 if (request_module("nfct-helper-%s", name) == 0)
165 h = __nf_conntrack_helper_find(name, l3num, protonum);
166 }
167#endif
168 if (h != NULL && !try_module_get(h->me))
169 h = NULL;
170
171 return h;
172}
173EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
174
175struct nf_conn_help *
176nf_ct_helper_ext_add(struct nf_conn *ct,
177 struct nf_conntrack_helper *helper, gfp_t gfp)
178{
179 struct nf_conn_help *help;
180
181 help = nf_ct_ext_add_length(ct, NF_CT_EXT_HELPER,
182 helper->data_len, gfp);
183 if (help)
184 INIT_HLIST_HEAD(&help->expectations);
185 else
186 pr_debug("failed to add helper extension area");
187 return help;
188}
189EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
190
191int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
192 gfp_t flags)
193{
194 struct nf_conntrack_helper *helper = NULL;
195 struct nf_conn_help *help;
196 struct net *net = nf_ct_net(ct);
197
198
199
200
201
202
203
204 if (test_bit(IPS_HELPER_BIT, &ct->status))
205 return 0;
206
207 if (tmpl != NULL) {
208 help = nfct_help(tmpl);
209 if (help != NULL) {
210 helper = help->helper;
211 set_bit(IPS_HELPER_BIT, &ct->status);
212 }
213 }
214
215 help = nfct_help(ct);
216 if (net->ct.sysctl_auto_assign_helper && helper == NULL) {
217 helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
218 if (unlikely(!net->ct.auto_assign_helper_warned && helper)) {
219 pr_info("nf_conntrack: automatic helper "
220 "assignment is deprecated and it will "
221 "be removed soon. Use the iptables CT target "
222 "to attach helpers instead.\n");
223 net->ct.auto_assign_helper_warned = true;
224 }
225 }
226
227 if (helper == NULL) {
228 if (help)
229 RCU_INIT_POINTER(help->helper, NULL);
230 return 0;
231 }
232
233 if (help == NULL) {
234 help = nf_ct_helper_ext_add(ct, helper, flags);
235 if (help == NULL)
236 return -ENOMEM;
237 } else {
238
239
240
241 struct nf_conntrack_helper *tmp = rcu_dereference(help->helper);
242
243 if (tmp && tmp->help != helper->help) {
244 RCU_INIT_POINTER(help->helper, NULL);
245 return 0;
246 }
247 }
248
249 rcu_assign_pointer(help->helper, helper);
250
251 return 0;
252}
253EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
254
255
256static inline int unhelp(struct nf_conntrack_tuple_hash *i,
257 const struct nf_conntrack_helper *me)
258{
259 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
260 struct nf_conn_help *help = nfct_help(ct);
261
262 if (help && rcu_dereference_raw(help->helper) == me) {
263 nf_conntrack_event(IPCT_HELPER, ct);
264 RCU_INIT_POINTER(help->helper, NULL);
265 }
266 return 0;
267}
268
269void nf_ct_helper_destroy(struct nf_conn *ct)
270{
271 struct nf_conn_help *help = nfct_help(ct);
272 struct nf_conntrack_helper *helper;
273
274 if (help) {
275 rcu_read_lock();
276 helper = rcu_dereference(help->helper);
277 if (helper && helper->destroy)
278 helper->destroy(ct);
279 rcu_read_unlock();
280 }
281}
282
283static LIST_HEAD(nf_ct_helper_expectfn_list);
284
285void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
286{
287 spin_lock_bh(&nf_conntrack_expect_lock);
288 list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
289 spin_unlock_bh(&nf_conntrack_expect_lock);
290}
291EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);
292
293void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
294{
295 spin_lock_bh(&nf_conntrack_expect_lock);
296 list_del_rcu(&n->head);
297 spin_unlock_bh(&nf_conntrack_expect_lock);
298}
299EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
300
301struct nf_ct_helper_expectfn *
302nf_ct_helper_expectfn_find_by_name(const char *name)
303{
304 struct nf_ct_helper_expectfn *cur;
305 bool found = false;
306
307 rcu_read_lock();
308 list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
309 if (!strcmp(cur->name, name)) {
310 found = true;
311 break;
312 }
313 }
314 rcu_read_unlock();
315 return found ? cur : NULL;
316}
317EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);
318
319struct nf_ct_helper_expectfn *
320nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
321{
322 struct nf_ct_helper_expectfn *cur;
323 bool found = false;
324
325 rcu_read_lock();
326 list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
327 if (cur->expectfn == symbol) {
328 found = true;
329 break;
330 }
331 }
332 rcu_read_unlock();
333 return found ? cur : NULL;
334}
335EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
336
337__printf(3, 4)
338void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
339 const char *fmt, ...)
340{
341 const struct nf_conn_help *help;
342 const struct nf_conntrack_helper *helper;
343 struct va_format vaf;
344 va_list args;
345
346 va_start(args, fmt);
347
348 vaf.fmt = fmt;
349 vaf.va = &args;
350
351
352 help = nfct_help(ct);
353
354
355 helper = rcu_dereference(help->helper);
356
357 nf_log_packet(nf_ct_net(ct), nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL,
358 "nf_ct_%s: dropping packet: %pV ", helper->name, &vaf);
359
360 va_end(args);
361}
362EXPORT_SYMBOL_GPL(nf_ct_helper_log);
363
364int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
365{
366 struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
367 unsigned int h = helper_hash(&me->tuple);
368 struct nf_conntrack_helper *cur;
369 int ret = 0;
370
371 BUG_ON(me->expect_policy == NULL);
372 BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
373 BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
374
375 mutex_lock(&nf_ct_helper_mutex);
376 hlist_for_each_entry(cur, &nf_ct_helper_hash[h], hnode) {
377 if (nf_ct_tuple_src_mask_cmp(&cur->tuple, &me->tuple, &mask)) {
378 ret = -EEXIST;
379 goto out;
380 }
381 }
382 hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
383 nf_ct_helper_count++;
384out:
385 mutex_unlock(&nf_ct_helper_mutex);
386 return ret;
387}
388EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
389
390static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
391 struct net *net)
392{
393 struct nf_conntrack_tuple_hash *h;
394 const struct hlist_nulls_node *nn;
395 int cpu;
396
397
398 for_each_possible_cpu(cpu) {
399 struct ct_pcpu *pcpu = per_cpu_ptr(net->ct.pcpu_lists, cpu);
400
401 spin_lock_bh(&pcpu->lock);
402 hlist_nulls_for_each_entry(h, nn, &pcpu->unconfirmed, hnnode)
403 unhelp(h, me);
404 spin_unlock_bh(&pcpu->lock);
405 }
406}
407
408void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
409{
410 struct nf_conntrack_tuple_hash *h;
411 struct nf_conntrack_expect *exp;
412 const struct hlist_node *next;
413 const struct hlist_nulls_node *nn;
414 unsigned int last_hsize;
415 spinlock_t *lock;
416 struct net *net;
417 unsigned int i;
418
419 mutex_lock(&nf_ct_helper_mutex);
420 hlist_del_rcu(&me->hnode);
421 nf_ct_helper_count--;
422 mutex_unlock(&nf_ct_helper_mutex);
423
424
425
426
427 synchronize_rcu();
428
429
430 spin_lock_bh(&nf_conntrack_expect_lock);
431 for (i = 0; i < nf_ct_expect_hsize; i++) {
432 hlist_for_each_entry_safe(exp, next,
433 &nf_ct_expect_hash[i], hnode) {
434 struct nf_conn_help *help = nfct_help(exp->master);
435 if ((rcu_dereference_protected(
436 help->helper,
437 lockdep_is_held(&nf_conntrack_expect_lock)
438 ) == me || exp->helper == me) &&
439 del_timer(&exp->timeout)) {
440 nf_ct_unlink_expect(exp);
441 nf_ct_expect_put(exp);
442 }
443 }
444 }
445 spin_unlock_bh(&nf_conntrack_expect_lock);
446
447 rtnl_lock();
448 for_each_net(net)
449 __nf_conntrack_helper_unregister(me, net);
450 rtnl_unlock();
451
452 local_bh_disable();
453restart:
454 last_hsize = nf_conntrack_htable_size;
455 for (i = 0; i < last_hsize; i++) {
456 lock = &nf_conntrack_locks[i % CONNTRACK_LOCKS];
457 nf_conntrack_lock(lock);
458 if (last_hsize != nf_conntrack_htable_size) {
459 spin_unlock(lock);
460 goto restart;
461 }
462 hlist_nulls_for_each_entry(h, nn, &nf_conntrack_hash[i], hnnode)
463 unhelp(h, me);
464 spin_unlock(lock);
465 }
466 local_bh_enable();
467}
468EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
469
470void nf_ct_helper_init(struct nf_conntrack_helper *helper,
471 u16 l3num, u16 protonum, const char *name,
472 u16 default_port, u16 spec_port, u32 id,
473 const struct nf_conntrack_expect_policy *exp_pol,
474 u32 expect_class_max, u32 data_len,
475 int (*help)(struct sk_buff *skb, unsigned int protoff,
476 struct nf_conn *ct,
477 enum ip_conntrack_info ctinfo),
478 int (*from_nlattr)(struct nlattr *attr,
479 struct nf_conn *ct),
480 struct module *module)
481{
482 helper->tuple.src.l3num = l3num;
483 helper->tuple.dst.protonum = protonum;
484 helper->tuple.src.u.all = htons(spec_port);
485 helper->expect_policy = exp_pol;
486 helper->expect_class_max = expect_class_max;
487 helper->data_len = data_len;
488 helper->help = help;
489 helper->from_nlattr = from_nlattr;
490 helper->me = module;
491
492 if (spec_port == default_port)
493 snprintf(helper->name, sizeof(helper->name), "%s", name);
494 else
495 snprintf(helper->name, sizeof(helper->name), "%s-%u", name, id);
496}
497EXPORT_SYMBOL_GPL(nf_ct_helper_init);
498
499int nf_conntrack_helpers_register(struct nf_conntrack_helper *helper,
500 unsigned int n)
501{
502 unsigned int i;
503 int err = 0;
504
505 for (i = 0; i < n; i++) {
506 err = nf_conntrack_helper_register(&helper[i]);
507 if (err < 0)
508 goto err;
509 }
510
511 return err;
512err:
513 if (i > 0)
514 nf_conntrack_helpers_unregister(helper, i);
515 return err;
516}
517EXPORT_SYMBOL_GPL(nf_conntrack_helpers_register);
518
519void nf_conntrack_helpers_unregister(struct nf_conntrack_helper *helper,
520 unsigned int n)
521{
522 while (n-- > 0)
523 nf_conntrack_helper_unregister(&helper[n]);
524}
525EXPORT_SYMBOL_GPL(nf_conntrack_helpers_unregister);
526
527static struct nf_ct_ext_type helper_extend __read_mostly = {
528 .len = sizeof(struct nf_conn_help),
529 .align = __alignof__(struct nf_conn_help),
530 .id = NF_CT_EXT_HELPER,
531};
532
533int nf_conntrack_helper_pernet_init(struct net *net)
534{
535 net->ct.auto_assign_helper_warned = false;
536 net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
537 return nf_conntrack_helper_init_sysctl(net);
538}
539
540void nf_conntrack_helper_pernet_fini(struct net *net)
541{
542 nf_conntrack_helper_fini_sysctl(net);
543}
544
545int nf_conntrack_helper_init(void)
546{
547 int ret;
548 nf_ct_helper_hsize = 1;
549 nf_ct_helper_hash =
550 nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
551 if (!nf_ct_helper_hash)
552 return -ENOMEM;
553
554 ret = nf_ct_extend_register(&helper_extend);
555 if (ret < 0) {
556 pr_err("nf_ct_helper: Unable to register helper extension.\n");
557 goto out_extend;
558 }
559
560 return 0;
561out_extend:
562 nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
563 return ret;
564}
565
566void nf_conntrack_helper_fini(void)
567{
568 nf_ct_extend_unregister(&helper_extend);
569 nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
570}
571
