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Linux/net/netfilter/nf_conntrack_proto.c

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  1 /* L3/L4 protocol support for nf_conntrack. */
  2 
  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>
  7  *
  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.
 11  */
 12 
 13 #include <linux/types.h>
 14 #include <linux/netfilter.h>
 15 #include <linux/module.h>
 16 #include <linux/slab.h>
 17 #include <linux/mutex.h>
 18 #include <linux/vmalloc.h>
 19 #include <linux/stddef.h>
 20 #include <linux/err.h>
 21 #include <linux/percpu.h>
 22 #include <linux/notifier.h>
 23 #include <linux/kernel.h>
 24 #include <linux/netdevice.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_core.h>
 30 
 31 static struct nf_conntrack_l4proto __rcu **nf_ct_protos[NFPROTO_NUMPROTO] __read_mostly;
 32 struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[NFPROTO_NUMPROTO] __read_mostly;
 33 EXPORT_SYMBOL_GPL(nf_ct_l3protos);
 34 
 35 static DEFINE_MUTEX(nf_ct_proto_mutex);
 36 
 37 #ifdef CONFIG_SYSCTL
 38 static int
 39 nf_ct_register_sysctl(struct net *net,
 40                       struct ctl_table_header **header,
 41                       const char *path,
 42                       struct ctl_table *table)
 43 {
 44         if (*header == NULL) {
 45                 *header = register_net_sysctl(net, path, table);
 46                 if (*header == NULL)
 47                         return -ENOMEM;
 48         }
 49 
 50         return 0;
 51 }
 52 
 53 static void
 54 nf_ct_unregister_sysctl(struct ctl_table_header **header,
 55                         struct ctl_table **table,
 56                         unsigned int users)
 57 {
 58         if (users > 0)
 59                 return;
 60 
 61         unregister_net_sysctl_table(*header);
 62         kfree(*table);
 63         *header = NULL;
 64         *table = NULL;
 65 }
 66 #endif
 67 
 68 struct nf_conntrack_l4proto *
 69 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
 70 {
 71         if (unlikely(l3proto >= NFPROTO_NUMPROTO || nf_ct_protos[l3proto] == NULL))
 72                 return &nf_conntrack_l4proto_generic;
 73 
 74         return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
 75 }
 76 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
 77 
 78 /* this is guaranteed to always return a valid protocol helper, since
 79  * it falls back to generic_protocol */
 80 struct nf_conntrack_l3proto *
 81 nf_ct_l3proto_find_get(u_int16_t l3proto)
 82 {
 83         struct nf_conntrack_l3proto *p;
 84 
 85         rcu_read_lock();
 86         p = __nf_ct_l3proto_find(l3proto);
 87         if (!try_module_get(p->me))
 88                 p = &nf_conntrack_l3proto_generic;
 89         rcu_read_unlock();
 90 
 91         return p;
 92 }
 93 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
 94 
 95 int
 96 nf_ct_l3proto_try_module_get(unsigned short l3proto)
 97 {
 98         int ret;
 99         struct nf_conntrack_l3proto *p;
100 
101 retry:  p = nf_ct_l3proto_find_get(l3proto);
102         if (p == &nf_conntrack_l3proto_generic) {
103                 ret = request_module("nf_conntrack-%d", l3proto);
104                 if (!ret)
105                         goto retry;
106 
107                 return -EPROTOTYPE;
108         }
109 
110         return 0;
111 }
112 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
113 
114 void nf_ct_l3proto_module_put(unsigned short l3proto)
115 {
116         struct nf_conntrack_l3proto *p;
117 
118         /* rcu_read_lock not necessary since the caller holds a reference, but
119          * taken anyways to avoid lockdep warnings in __nf_ct_l3proto_find()
120          */
121         rcu_read_lock();
122         p = __nf_ct_l3proto_find(l3proto);
123         module_put(p->me);
124         rcu_read_unlock();
125 }
126 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
127 
128 int nf_ct_netns_get(struct net *net, u8 nfproto)
129 {
130         const struct nf_conntrack_l3proto *l3proto;
131         int ret;
132 
133         might_sleep();
134 
135         ret = nf_ct_l3proto_try_module_get(nfproto);
136         if (ret < 0)
137                 return ret;
138 
139         /* we already have a reference, can't fail */
140         rcu_read_lock();
141         l3proto = __nf_ct_l3proto_find(nfproto);
142         rcu_read_unlock();
143 
144         if (!l3proto->net_ns_get)
145                 return 0;
146 
147         ret = l3proto->net_ns_get(net);
148         if (ret < 0)
149                 nf_ct_l3proto_module_put(nfproto);
150 
151         return ret;
152 }
153 EXPORT_SYMBOL_GPL(nf_ct_netns_get);
154 
155 void nf_ct_netns_put(struct net *net, u8 nfproto)
156 {
157         const struct nf_conntrack_l3proto *l3proto;
158 
159         might_sleep();
160 
161         /* same as nf_conntrack_netns_get(), reference assumed */
162         rcu_read_lock();
163         l3proto = __nf_ct_l3proto_find(nfproto);
164         rcu_read_unlock();
165 
166         if (WARN_ON(!l3proto))
167                 return;
168 
169         if (l3proto->net_ns_put)
170                 l3proto->net_ns_put(net);
171 
172         nf_ct_l3proto_module_put(nfproto);
173 }
174 EXPORT_SYMBOL_GPL(nf_ct_netns_put);
175 
176 struct nf_conntrack_l4proto *
177 nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
178 {
179         struct nf_conntrack_l4proto *p;
180 
181         rcu_read_lock();
182         p = __nf_ct_l4proto_find(l3num, l4num);
183         if (!try_module_get(p->me))
184                 p = &nf_conntrack_l4proto_generic;
185         rcu_read_unlock();
186 
187         return p;
188 }
189 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
190 
191 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
192 {
193         module_put(p->me);
194 }
195 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
196 
197 static int kill_l3proto(struct nf_conn *i, void *data)
198 {
199         return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
200 }
201 
202 static int kill_l4proto(struct nf_conn *i, void *data)
203 {
204         struct nf_conntrack_l4proto *l4proto;
205         l4proto = data;
206         return nf_ct_protonum(i) == l4proto->l4proto &&
207                nf_ct_l3num(i) == l4proto->l3proto;
208 }
209 
210 int nf_ct_l3proto_register(struct nf_conntrack_l3proto *proto)
211 {
212         int ret = 0;
213         struct nf_conntrack_l3proto *old;
214 
215         if (proto->l3proto >= NFPROTO_NUMPROTO)
216                 return -EBUSY;
217 
218         if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
219                 return -EINVAL;
220 
221         mutex_lock(&nf_ct_proto_mutex);
222         old = rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
223                                         lockdep_is_held(&nf_ct_proto_mutex));
224         if (old != &nf_conntrack_l3proto_generic) {
225                 ret = -EBUSY;
226                 goto out_unlock;
227         }
228 
229         if (proto->nlattr_tuple_size)
230                 proto->nla_size = 3 * proto->nlattr_tuple_size();
231 
232         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
233 
234 out_unlock:
235         mutex_unlock(&nf_ct_proto_mutex);
236         return ret;
237 
238 }
239 EXPORT_SYMBOL_GPL(nf_ct_l3proto_register);
240 
241 #ifdef CONFIG_SYSCTL
242 extern unsigned int nf_conntrack_default_on;
243 
244 int nf_ct_l3proto_pernet_register(struct net *net,
245                                   struct nf_conntrack_l3proto *proto)
246 {
247         if (nf_conntrack_default_on == 0)
248                 return 0;
249 
250         return proto->net_ns_get ? proto->net_ns_get(net) : 0;
251 }
252 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_register);
253 #endif
254 
255 void nf_ct_l3proto_unregister(struct nf_conntrack_l3proto *proto)
256 {
257         BUG_ON(proto->l3proto >= NFPROTO_NUMPROTO);
258 
259         mutex_lock(&nf_ct_proto_mutex);
260         BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
261                                          lockdep_is_held(&nf_ct_proto_mutex)
262                                          ) != proto);
263         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
264                            &nf_conntrack_l3proto_generic);
265         mutex_unlock(&nf_ct_proto_mutex);
266 
267         synchronize_rcu();
268         /* Remove all contrack entries for this protocol */
269         nf_ct_iterate_destroy(kill_l3proto, proto);
270 }
271 EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);
272 
273 void nf_ct_l3proto_pernet_unregister(struct net *net,
274                                      struct nf_conntrack_l3proto *proto)
275 {
276         /*
277          * nf_conntrack_default_on *might* have registered hooks.
278          * ->net_ns_put must cope with more puts() than get(), i.e.
279          * if nf_conntrack_default_on was 0 at time of
280          * nf_ct_l3proto_pernet_register invocation this net_ns_put()
281          * should be a noop.
282          */
283         if (proto->net_ns_put)
284                 proto->net_ns_put(net);
285 }
286 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_unregister);
287 
288 static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,
289                                               struct nf_conntrack_l4proto *l4proto)
290 {
291         if (l4proto->get_net_proto) {
292                 /* statically built-in protocols use static per-net */
293                 return l4proto->get_net_proto(net);
294         } else if (l4proto->net_id) {
295                 /* ... and loadable protocols use dynamic per-net */
296                 return net_generic(net, *l4proto->net_id);
297         }
298         return NULL;
299 }
300 
301 static
302 int nf_ct_l4proto_register_sysctl(struct net *net,
303                                   struct nf_proto_net *pn,
304                                   struct nf_conntrack_l4proto *l4proto)
305 {
306         int err = 0;
307 
308 #ifdef CONFIG_SYSCTL
309         if (pn->ctl_table != NULL) {
310                 err = nf_ct_register_sysctl(net,
311                                             &pn->ctl_table_header,
312                                             "net/netfilter",
313                                             pn->ctl_table);
314                 if (err < 0) {
315                         if (!pn->users) {
316                                 kfree(pn->ctl_table);
317                                 pn->ctl_table = NULL;
318                         }
319                 }
320         }
321 #endif /* CONFIG_SYSCTL */
322         return err;
323 }
324 
325 static
326 void nf_ct_l4proto_unregister_sysctl(struct net *net,
327                                      struct nf_proto_net *pn,
328                                      struct nf_conntrack_l4proto *l4proto)
329 {
330 #ifdef CONFIG_SYSCTL
331         if (pn->ctl_table_header != NULL)
332                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
333                                         &pn->ctl_table,
334                                         pn->users);
335 #endif /* CONFIG_SYSCTL */
336 }
337 
338 /* FIXME: Allow NULL functions and sub in pointers to generic for
339    them. --RR */
340 int nf_ct_l4proto_register_one(struct nf_conntrack_l4proto *l4proto)
341 {
342         int ret = 0;
343 
344         if (l4proto->l3proto >= ARRAY_SIZE(nf_ct_protos))
345                 return -EBUSY;
346 
347         if ((l4proto->to_nlattr && !l4proto->nlattr_size) ||
348             (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
349                 return -EINVAL;
350 
351         mutex_lock(&nf_ct_proto_mutex);
352         if (!nf_ct_protos[l4proto->l3proto]) {
353                 /* l3proto may be loaded latter. */
354                 struct nf_conntrack_l4proto __rcu **proto_array;
355                 int i;
356 
357                 proto_array = kmalloc(MAX_NF_CT_PROTO *
358                                       sizeof(struct nf_conntrack_l4proto *),
359                                       GFP_KERNEL);
360                 if (proto_array == NULL) {
361                         ret = -ENOMEM;
362                         goto out_unlock;
363                 }
364 
365                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
366                         RCU_INIT_POINTER(proto_array[i],
367                                          &nf_conntrack_l4proto_generic);
368 
369                 /* Before making proto_array visible to lockless readers,
370                  * we must make sure its content is committed to memory.
371                  */
372                 smp_wmb();
373 
374                 nf_ct_protos[l4proto->l3proto] = proto_array;
375         } else if (rcu_dereference_protected(
376                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
377                         lockdep_is_held(&nf_ct_proto_mutex)
378                         ) != &nf_conntrack_l4proto_generic) {
379                 ret = -EBUSY;
380                 goto out_unlock;
381         }
382 
383         l4proto->nla_size = 0;
384         if (l4proto->nlattr_size)
385                 l4proto->nla_size += l4proto->nlattr_size();
386         if (l4proto->nlattr_tuple_size)
387                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
388 
389         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
390                            l4proto);
391 out_unlock:
392         mutex_unlock(&nf_ct_proto_mutex);
393         return ret;
394 }
395 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register_one);
396 
397 int nf_ct_l4proto_pernet_register_one(struct net *net,
398                                       struct nf_conntrack_l4proto *l4proto)
399 {
400         int ret = 0;
401         struct nf_proto_net *pn = NULL;
402 
403         if (l4proto->init_net) {
404                 ret = l4proto->init_net(net, l4proto->l3proto);
405                 if (ret < 0)
406                         goto out;
407         }
408 
409         pn = nf_ct_l4proto_net(net, l4proto);
410         if (pn == NULL)
411                 goto out;
412 
413         ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
414         if (ret < 0)
415                 goto out;
416 
417         pn->users++;
418 out:
419         return ret;
420 }
421 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register_one);
422 
423 static void __nf_ct_l4proto_unregister_one(struct nf_conntrack_l4proto *l4proto)
424 
425 {
426         BUG_ON(l4proto->l3proto >= ARRAY_SIZE(nf_ct_protos));
427 
428         BUG_ON(rcu_dereference_protected(
429                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
430                         lockdep_is_held(&nf_ct_proto_mutex)
431                         ) != l4proto);
432         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
433                            &nf_conntrack_l4proto_generic);
434 }
435 
436 void nf_ct_l4proto_unregister_one(struct nf_conntrack_l4proto *l4proto)
437 {
438         mutex_lock(&nf_ct_proto_mutex);
439         __nf_ct_l4proto_unregister_one(l4proto);
440         mutex_unlock(&nf_ct_proto_mutex);
441 
442         synchronize_rcu();
443 }
444 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister_one);
445 
446 void nf_ct_l4proto_pernet_unregister_one(struct net *net,
447                                          struct nf_conntrack_l4proto *l4proto)
448 {
449         struct nf_proto_net *pn = nf_ct_l4proto_net(net, l4proto);
450 
451         if (pn == NULL)
452                 return;
453 
454         pn->users--;
455         nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
456 }
457 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister_one);
458 
459 int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto[],
460                            unsigned int num_proto)
461 {
462         int ret = -EINVAL, ver;
463         unsigned int i;
464 
465         for (i = 0; i < num_proto; i++) {
466                 ret = nf_ct_l4proto_register_one(l4proto[i]);
467                 if (ret < 0)
468                         break;
469         }
470         if (i != num_proto) {
471                 ver = l4proto[i]->l3proto == PF_INET6 ? 6 : 4;
472                 pr_err("nf_conntrack_ipv%d: can't register %s%d proto.\n",
473                        ver, l4proto[i]->name, ver);
474                 nf_ct_l4proto_unregister(l4proto, i);
475         }
476         return ret;
477 }
478 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);
479 
480 int nf_ct_l4proto_pernet_register(struct net *net,
481                                   struct nf_conntrack_l4proto *l4proto[],
482                                   unsigned int num_proto)
483 {
484         int ret = -EINVAL;
485         unsigned int i;
486 
487         for (i = 0; i < num_proto; i++) {
488                 ret = nf_ct_l4proto_pernet_register_one(net, l4proto[i]);
489                 if (ret < 0)
490                         break;
491         }
492         if (i != num_proto) {
493                 pr_err("nf_conntrack_%s%d: pernet registration failed\n",
494                        l4proto[i]->name,
495                        l4proto[i]->l3proto == PF_INET6 ? 6 : 4);
496                 nf_ct_l4proto_pernet_unregister(net, l4proto, i);
497         }
498         return ret;
499 }
500 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);
501 
502 void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto[],
503                               unsigned int num_proto)
504 {
505         mutex_lock(&nf_ct_proto_mutex);
506         while (num_proto-- != 0)
507                 __nf_ct_l4proto_unregister_one(l4proto[num_proto]);
508         mutex_unlock(&nf_ct_proto_mutex);
509 
510         synchronize_net();
511         /* Remove all contrack entries for this protocol */
512         nf_ct_iterate_destroy(kill_l4proto, l4proto);
513 }
514 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);
515 
516 void nf_ct_l4proto_pernet_unregister(struct net *net,
517                                      struct nf_conntrack_l4proto *l4proto[],
518                                      unsigned int num_proto)
519 {
520         while (num_proto-- != 0)
521                 nf_ct_l4proto_pernet_unregister_one(net, l4proto[num_proto]);
522 }
523 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);
524 
525 int nf_conntrack_proto_pernet_init(struct net *net)
526 {
527         int err;
528         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
529                                         &nf_conntrack_l4proto_generic);
530 
531         err = nf_conntrack_l4proto_generic.init_net(net,
532                                         nf_conntrack_l4proto_generic.l3proto);
533         if (err < 0)
534                 return err;
535         err = nf_ct_l4proto_register_sysctl(net,
536                                             pn,
537                                             &nf_conntrack_l4proto_generic);
538         if (err < 0)
539                 return err;
540 
541         pn->users++;
542         return 0;
543 }
544 
545 void nf_conntrack_proto_pernet_fini(struct net *net)
546 {
547         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
548                                         &nf_conntrack_l4proto_generic);
549 
550         pn->users--;
551         nf_ct_l4proto_unregister_sysctl(net,
552                                         pn,
553                                         &nf_conntrack_l4proto_generic);
554 }
555 
556 int nf_conntrack_proto_init(void)
557 {
558         unsigned int i;
559         for (i = 0; i < NFPROTO_NUMPROTO; i++)
560                 rcu_assign_pointer(nf_ct_l3protos[i],
561                                    &nf_conntrack_l3proto_generic);
562         return 0;
563 }
564 
565 void nf_conntrack_proto_fini(void)
566 {
567         unsigned int i;
568         /* free l3proto protocol tables */
569         for (i = 0; i < ARRAY_SIZE(nf_ct_protos); i++)
570                 kfree(nf_ct_protos[i]);
571 }
572 

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