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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[PF_MAX] __read_mostly;
 32 struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[AF_MAX] __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 >= AF_MAX || 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 = (struct nf_conntrack_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 >= AF_MAX)
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 >= AF_MAX);
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 }
269 EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);
270 
271 void nf_ct_l3proto_pernet_unregister(struct net *net,
272                                      struct nf_conntrack_l3proto *proto)
273 {
274         /*
275          * nf_conntrack_default_on *might* have registered hooks.
276          * ->net_ns_put must cope with more puts() than get(), i.e.
277          * if nf_conntrack_default_on was 0 at time of
278          * nf_ct_l3proto_pernet_register invocation this net_ns_put()
279          * should be a noop.
280          */
281         if (proto->net_ns_put)
282                 proto->net_ns_put(net);
283 
284         /* Remove all contrack entries for this protocol */
285         nf_ct_iterate_cleanup(net, kill_l3proto, proto, 0, 0);
286 }
287 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_unregister);
288 
289 static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,
290                                               struct nf_conntrack_l4proto *l4proto)
291 {
292         if (l4proto->get_net_proto) {
293                 /* statically built-in protocols use static per-net */
294                 return l4proto->get_net_proto(net);
295         } else if (l4proto->net_id) {
296                 /* ... and loadable protocols use dynamic per-net */
297                 return net_generic(net, *l4proto->net_id);
298         }
299         return NULL;
300 }
301 
302 static
303 int nf_ct_l4proto_register_sysctl(struct net *net,
304                                   struct nf_proto_net *pn,
305                                   struct nf_conntrack_l4proto *l4proto)
306 {
307         int err = 0;
308 
309 #ifdef CONFIG_SYSCTL
310         if (pn->ctl_table != NULL) {
311                 err = nf_ct_register_sysctl(net,
312                                             &pn->ctl_table_header,
313                                             "net/netfilter",
314                                             pn->ctl_table);
315                 if (err < 0) {
316                         if (!pn->users) {
317                                 kfree(pn->ctl_table);
318                                 pn->ctl_table = NULL;
319                         }
320                 }
321         }
322 #endif /* CONFIG_SYSCTL */
323         return err;
324 }
325 
326 static
327 void nf_ct_l4proto_unregister_sysctl(struct net *net,
328                                      struct nf_proto_net *pn,
329                                      struct nf_conntrack_l4proto *l4proto)
330 {
331 #ifdef CONFIG_SYSCTL
332         if (pn->ctl_table_header != NULL)
333                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
334                                         &pn->ctl_table,
335                                         pn->users);
336 #endif /* CONFIG_SYSCTL */
337 }
338 
339 /* FIXME: Allow NULL functions and sub in pointers to generic for
340    them. --RR */
341 int nf_ct_l4proto_register_one(struct nf_conntrack_l4proto *l4proto)
342 {
343         int ret = 0;
344 
345         if (l4proto->l3proto >= PF_MAX)
346                 return -EBUSY;
347 
348         if ((l4proto->to_nlattr && !l4proto->nlattr_size) ||
349             (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
350                 return -EINVAL;
351 
352         mutex_lock(&nf_ct_proto_mutex);
353         if (!nf_ct_protos[l4proto->l3proto]) {
354                 /* l3proto may be loaded latter. */
355                 struct nf_conntrack_l4proto __rcu **proto_array;
356                 int i;
357 
358                 proto_array = kmalloc(MAX_NF_CT_PROTO *
359                                       sizeof(struct nf_conntrack_l4proto *),
360                                       GFP_KERNEL);
361                 if (proto_array == NULL) {
362                         ret = -ENOMEM;
363                         goto out_unlock;
364                 }
365 
366                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
367                         RCU_INIT_POINTER(proto_array[i],
368                                          &nf_conntrack_l4proto_generic);
369 
370                 /* Before making proto_array visible to lockless readers,
371                  * we must make sure its content is committed to memory.
372                  */
373                 smp_wmb();
374 
375                 nf_ct_protos[l4proto->l3proto] = proto_array;
376         } else if (rcu_dereference_protected(
377                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
378                         lockdep_is_held(&nf_ct_proto_mutex)
379                         ) != &nf_conntrack_l4proto_generic) {
380                 ret = -EBUSY;
381                 goto out_unlock;
382         }
383 
384         l4proto->nla_size = 0;
385         if (l4proto->nlattr_size)
386                 l4proto->nla_size += l4proto->nlattr_size();
387         if (l4proto->nlattr_tuple_size)
388                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
389 
390         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
391                            l4proto);
392 out_unlock:
393         mutex_unlock(&nf_ct_proto_mutex);
394         return ret;
395 }
396 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register_one);
397 
398 int nf_ct_l4proto_pernet_register_one(struct net *net,
399                                       struct nf_conntrack_l4proto *l4proto)
400 {
401         int ret = 0;
402         struct nf_proto_net *pn = NULL;
403 
404         if (l4proto->init_net) {
405                 ret = l4proto->init_net(net, l4proto->l3proto);
406                 if (ret < 0)
407                         goto out;
408         }
409 
410         pn = nf_ct_l4proto_net(net, l4proto);
411         if (pn == NULL)
412                 goto out;
413 
414         ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
415         if (ret < 0)
416                 goto out;
417 
418         pn->users++;
419 out:
420         return ret;
421 }
422 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register_one);
423 
424 void nf_ct_l4proto_unregister_one(struct nf_conntrack_l4proto *l4proto)
425 {
426         BUG_ON(l4proto->l3proto >= PF_MAX);
427 
428         mutex_lock(&nf_ct_proto_mutex);
429         BUG_ON(rcu_dereference_protected(
430                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
431                         lockdep_is_held(&nf_ct_proto_mutex)
432                         ) != l4proto);
433         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
434                            &nf_conntrack_l4proto_generic);
435         mutex_unlock(&nf_ct_proto_mutex);
436 
437         synchronize_rcu();
438 }
439 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister_one);
440 
441 void nf_ct_l4proto_pernet_unregister_one(struct net *net,
442                                          struct nf_conntrack_l4proto *l4proto)
443 {
444         struct nf_proto_net *pn = NULL;
445 
446         pn = nf_ct_l4proto_net(net, l4proto);
447         if (pn == NULL)
448                 return;
449 
450         pn->users--;
451         nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
452 
453         /* Remove all contrack entries for this protocol */
454         nf_ct_iterate_cleanup(net, kill_l4proto, l4proto, 0, 0);
455 }
456 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister_one);
457 
458 int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto[],
459                            unsigned int num_proto)
460 {
461         int ret = -EINVAL, ver;
462         unsigned int i;
463 
464         for (i = 0; i < num_proto; i++) {
465                 ret = nf_ct_l4proto_register_one(l4proto[i]);
466                 if (ret < 0)
467                         break;
468         }
469         if (i != num_proto) {
470                 ver = l4proto[i]->l3proto == PF_INET6 ? 6 : 4;
471                 pr_err("nf_conntrack_ipv%d: can't register %s%d proto.\n",
472                        ver, l4proto[i]->name, ver);
473                 nf_ct_l4proto_unregister(l4proto, i);
474         }
475         return ret;
476 }
477 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);
478 
479 int nf_ct_l4proto_pernet_register(struct net *net,
480                                   struct nf_conntrack_l4proto *l4proto[],
481                                   unsigned int num_proto)
482 {
483         int ret = -EINVAL;
484         unsigned int i;
485 
486         for (i = 0; i < num_proto; i++) {
487                 ret = nf_ct_l4proto_pernet_register_one(net, l4proto[i]);
488                 if (ret < 0)
489                         break;
490         }
491         if (i != num_proto) {
492                 pr_err("nf_conntrack_%s%d: pernet registration failed\n",
493                        l4proto[i]->name,
494                        l4proto[i]->l3proto == PF_INET6 ? 6 : 4);
495                 nf_ct_l4proto_pernet_unregister(net, l4proto, i);
496         }
497         return ret;
498 }
499 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);
500 
501 void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto[],
502                               unsigned int num_proto)
503 {
504         while (num_proto-- != 0)
505                 nf_ct_l4proto_unregister_one(l4proto[num_proto]);
506 }
507 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);
508 
509 void nf_ct_l4proto_pernet_unregister(struct net *net,
510                                      struct nf_conntrack_l4proto *l4proto[],
511                                      unsigned int num_proto)
512 {
513         while (num_proto-- != 0)
514                 nf_ct_l4proto_pernet_unregister_one(net, l4proto[num_proto]);
515 }
516 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);
517 
518 int nf_conntrack_proto_pernet_init(struct net *net)
519 {
520         int err;
521         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
522                                         &nf_conntrack_l4proto_generic);
523 
524         err = nf_conntrack_l4proto_generic.init_net(net,
525                                         nf_conntrack_l4proto_generic.l3proto);
526         if (err < 0)
527                 return err;
528         err = nf_ct_l4proto_register_sysctl(net,
529                                             pn,
530                                             &nf_conntrack_l4proto_generic);
531         if (err < 0)
532                 return err;
533 
534         pn->users++;
535         return 0;
536 }
537 
538 void nf_conntrack_proto_pernet_fini(struct net *net)
539 {
540         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
541                                         &nf_conntrack_l4proto_generic);
542 
543         pn->users--;
544         nf_ct_l4proto_unregister_sysctl(net,
545                                         pn,
546                                         &nf_conntrack_l4proto_generic);
547 }
548 
549 int nf_conntrack_proto_init(void)
550 {
551         unsigned int i;
552         for (i = 0; i < AF_MAX; i++)
553                 rcu_assign_pointer(nf_ct_l3protos[i],
554                                    &nf_conntrack_l3proto_generic);
555         return 0;
556 }
557 
558 void nf_conntrack_proto_fini(void)
559 {
560         unsigned int i;
561         /* free l3proto protocol tables */
562         for (i = 0; i < PF_MAX; i++)
563                 kfree(nf_ct_protos[i]);
564 }
565 

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