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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 void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
 96 {
 97         module_put(p->me);
 98 }
 99 EXPORT_SYMBOL_GPL(nf_ct_l3proto_put);
100 
101 int
102 nf_ct_l3proto_try_module_get(unsigned short l3proto)
103 {
104         int ret;
105         struct nf_conntrack_l3proto *p;
106 
107 retry:  p = nf_ct_l3proto_find_get(l3proto);
108         if (p == &nf_conntrack_l3proto_generic) {
109                 ret = request_module("nf_conntrack-%d", l3proto);
110                 if (!ret)
111                         goto retry;
112 
113                 return -EPROTOTYPE;
114         }
115 
116         return 0;
117 }
118 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
119 
120 void nf_ct_l3proto_module_put(unsigned short l3proto)
121 {
122         struct nf_conntrack_l3proto *p;
123 
124         /* rcu_read_lock not necessary since the caller holds a reference, but
125          * taken anyways to avoid lockdep warnings in __nf_ct_l3proto_find()
126          */
127         rcu_read_lock();
128         p = __nf_ct_l3proto_find(l3proto);
129         module_put(p->me);
130         rcu_read_unlock();
131 }
132 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
133 
134 struct nf_conntrack_l4proto *
135 nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
136 {
137         struct nf_conntrack_l4proto *p;
138 
139         rcu_read_lock();
140         p = __nf_ct_l4proto_find(l3num, l4num);
141         if (!try_module_get(p->me))
142                 p = &nf_conntrack_l4proto_generic;
143         rcu_read_unlock();
144 
145         return p;
146 }
147 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
148 
149 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
150 {
151         module_put(p->me);
152 }
153 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
154 
155 static int kill_l3proto(struct nf_conn *i, void *data)
156 {
157         return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
158 }
159 
160 static int kill_l4proto(struct nf_conn *i, void *data)
161 {
162         struct nf_conntrack_l4proto *l4proto;
163         l4proto = (struct nf_conntrack_l4proto *)data;
164         return nf_ct_protonum(i) == l4proto->l4proto &&
165                nf_ct_l3num(i) == l4proto->l3proto;
166 }
167 
168 static struct nf_ip_net *nf_ct_l3proto_net(struct net *net,
169                                            struct nf_conntrack_l3proto *l3proto)
170 {
171         if (l3proto->l3proto == PF_INET)
172                 return &net->ct.nf_ct_proto;
173         else
174                 return NULL;
175 }
176 
177 static int nf_ct_l3proto_register_sysctl(struct net *net,
178                                          struct nf_conntrack_l3proto *l3proto)
179 {
180         int err = 0;
181         struct nf_ip_net *in = nf_ct_l3proto_net(net, l3proto);
182         /* nf_conntrack_l3proto_ipv6 doesn't support sysctl */
183         if (in == NULL)
184                 return 0;
185 
186 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
187         if (in->ctl_table != NULL) {
188                 err = nf_ct_register_sysctl(net,
189                                             &in->ctl_table_header,
190                                             l3proto->ctl_table_path,
191                                             in->ctl_table);
192                 if (err < 0) {
193                         kfree(in->ctl_table);
194                         in->ctl_table = NULL;
195                 }
196         }
197 #endif
198         return err;
199 }
200 
201 static void nf_ct_l3proto_unregister_sysctl(struct net *net,
202                                             struct nf_conntrack_l3proto *l3proto)
203 {
204         struct nf_ip_net *in = nf_ct_l3proto_net(net, l3proto);
205 
206         if (in == NULL)
207                 return;
208 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
209         if (in->ctl_table_header != NULL)
210                 nf_ct_unregister_sysctl(&in->ctl_table_header,
211                                         &in->ctl_table,
212                                         0);
213 #endif
214 }
215 
216 int nf_ct_l3proto_register(struct nf_conntrack_l3proto *proto)
217 {
218         int ret = 0;
219         struct nf_conntrack_l3proto *old;
220 
221         if (proto->l3proto >= AF_MAX)
222                 return -EBUSY;
223 
224         if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
225                 return -EINVAL;
226 
227         mutex_lock(&nf_ct_proto_mutex);
228         old = rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
229                                         lockdep_is_held(&nf_ct_proto_mutex));
230         if (old != &nf_conntrack_l3proto_generic) {
231                 ret = -EBUSY;
232                 goto out_unlock;
233         }
234 
235         if (proto->nlattr_tuple_size)
236                 proto->nla_size = 3 * proto->nlattr_tuple_size();
237 
238         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
239 
240 out_unlock:
241         mutex_unlock(&nf_ct_proto_mutex);
242         return ret;
243 
244 }
245 EXPORT_SYMBOL_GPL(nf_ct_l3proto_register);
246 
247 int nf_ct_l3proto_pernet_register(struct net *net,
248                                   struct nf_conntrack_l3proto *proto)
249 {
250         int ret = 0;
251 
252         if (proto->init_net) {
253                 ret = proto->init_net(net);
254                 if (ret < 0)
255                         return ret;
256         }
257 
258         return nf_ct_l3proto_register_sysctl(net, proto);
259 }
260 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_register);
261 
262 void nf_ct_l3proto_unregister(struct nf_conntrack_l3proto *proto)
263 {
264         BUG_ON(proto->l3proto >= AF_MAX);
265 
266         mutex_lock(&nf_ct_proto_mutex);
267         BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
268                                          lockdep_is_held(&nf_ct_proto_mutex)
269                                          ) != proto);
270         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
271                            &nf_conntrack_l3proto_generic);
272         mutex_unlock(&nf_ct_proto_mutex);
273 
274         synchronize_rcu();
275 }
276 EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);
277 
278 void nf_ct_l3proto_pernet_unregister(struct net *net,
279                                      struct nf_conntrack_l3proto *proto)
280 {
281         nf_ct_l3proto_unregister_sysctl(net, proto);
282 
283         /* Remove all contrack entries for this protocol */
284         nf_ct_iterate_cleanup(net, kill_l3proto, proto);
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 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
322         if (l4proto->l3proto != AF_INET6 && pn->ctl_compat_table != NULL) {
323                 if (err < 0) {
324                         nf_ct_kfree_compat_sysctl_table(pn);
325                         goto out;
326                 }
327                 err = nf_ct_register_sysctl(net,
328                                             &pn->ctl_compat_header,
329                                             "net/ipv4/netfilter",
330                                             pn->ctl_compat_table);
331                 if (err == 0)
332                         goto out;
333 
334                 nf_ct_kfree_compat_sysctl_table(pn);
335                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
336                                         &pn->ctl_table,
337                                         pn->users);
338         }
339 out:
340 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
341 #endif /* CONFIG_SYSCTL */
342         return err;
343 }
344 
345 static
346 void nf_ct_l4proto_unregister_sysctl(struct net *net,
347                                      struct nf_proto_net *pn,
348                                      struct nf_conntrack_l4proto *l4proto)
349 {
350 #ifdef CONFIG_SYSCTL
351         if (pn->ctl_table_header != NULL)
352                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
353                                         &pn->ctl_table,
354                                         pn->users);
355 
356 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
357         if (l4proto->l3proto != AF_INET6 && pn->ctl_compat_header != NULL)
358                 nf_ct_unregister_sysctl(&pn->ctl_compat_header,
359                                         &pn->ctl_compat_table,
360                                         0);
361 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
362 #endif /* CONFIG_SYSCTL */
363 }
364 
365 /* FIXME: Allow NULL functions and sub in pointers to generic for
366    them. --RR */
367 int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto)
368 {
369         int ret = 0;
370 
371         if (l4proto->l3proto >= PF_MAX)
372                 return -EBUSY;
373 
374         if ((l4proto->to_nlattr && !l4proto->nlattr_size)
375                 || (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
376                 return -EINVAL;
377 
378         mutex_lock(&nf_ct_proto_mutex);
379         if (!nf_ct_protos[l4proto->l3proto]) {
380                 /* l3proto may be loaded latter. */
381                 struct nf_conntrack_l4proto __rcu **proto_array;
382                 int i;
383 
384                 proto_array = kmalloc(MAX_NF_CT_PROTO *
385                                       sizeof(struct nf_conntrack_l4proto *),
386                                       GFP_KERNEL);
387                 if (proto_array == NULL) {
388                         ret = -ENOMEM;
389                         goto out_unlock;
390                 }
391 
392                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
393                         RCU_INIT_POINTER(proto_array[i], &nf_conntrack_l4proto_generic);
394 
395                 /* Before making proto_array visible to lockless readers,
396                  * we must make sure its content is committed to memory.
397                  */
398                 smp_wmb();
399 
400                 nf_ct_protos[l4proto->l3proto] = proto_array;
401         } else if (rcu_dereference_protected(
402                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
403                         lockdep_is_held(&nf_ct_proto_mutex)
404                         ) != &nf_conntrack_l4proto_generic) {
405                 ret = -EBUSY;
406                 goto out_unlock;
407         }
408 
409         l4proto->nla_size = 0;
410         if (l4proto->nlattr_size)
411                 l4proto->nla_size += l4proto->nlattr_size();
412         if (l4proto->nlattr_tuple_size)
413                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
414 
415         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
416                            l4proto);
417 out_unlock:
418         mutex_unlock(&nf_ct_proto_mutex);
419         return ret;
420 }
421 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);
422 
423 int nf_ct_l4proto_pernet_register(struct net *net,
424                                   struct nf_conntrack_l4proto *l4proto)
425 {
426         int ret = 0;
427         struct nf_proto_net *pn = NULL;
428 
429         if (l4proto->init_net) {
430                 ret = l4proto->init_net(net, l4proto->l3proto);
431                 if (ret < 0)
432                         goto out;
433         }
434 
435         pn = nf_ct_l4proto_net(net, l4proto);
436         if (pn == NULL)
437                 goto out;
438 
439         ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
440         if (ret < 0)
441                 goto out;
442 
443         pn->users++;
444 out:
445         return ret;
446 }
447 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);
448 
449 void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
450 {
451         BUG_ON(l4proto->l3proto >= PF_MAX);
452 
453         mutex_lock(&nf_ct_proto_mutex);
454         BUG_ON(rcu_dereference_protected(
455                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
456                         lockdep_is_held(&nf_ct_proto_mutex)
457                         ) != l4proto);
458         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
459                            &nf_conntrack_l4proto_generic);
460         mutex_unlock(&nf_ct_proto_mutex);
461 
462         synchronize_rcu();
463 }
464 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);
465 
466 void nf_ct_l4proto_pernet_unregister(struct net *net,
467                                      struct nf_conntrack_l4proto *l4proto)
468 {
469         struct nf_proto_net *pn = NULL;
470 
471         pn = nf_ct_l4proto_net(net, l4proto);
472         if (pn == NULL)
473                 return;
474 
475         pn->users--;
476         nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
477 
478         /* Remove all contrack entries for this protocol */
479         nf_ct_iterate_cleanup(net, kill_l4proto, l4proto);
480 }
481 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);
482 
483 int nf_conntrack_proto_pernet_init(struct net *net)
484 {
485         int err;
486         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
487                                         &nf_conntrack_l4proto_generic);
488 
489         err = nf_conntrack_l4proto_generic.init_net(net,
490                                         nf_conntrack_l4proto_generic.l3proto);
491         if (err < 0)
492                 return err;
493         err = nf_ct_l4proto_register_sysctl(net,
494                                             pn,
495                                             &nf_conntrack_l4proto_generic);
496         if (err < 0)
497                 return err;
498 
499         pn->users++;
500         return 0;
501 }
502 
503 void nf_conntrack_proto_pernet_fini(struct net *net)
504 {
505         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
506                                         &nf_conntrack_l4proto_generic);
507 
508         pn->users--;
509         nf_ct_l4proto_unregister_sysctl(net,
510                                         pn,
511                                         &nf_conntrack_l4proto_generic);
512 }
513 
514 int nf_conntrack_proto_init(void)
515 {
516         unsigned int i;
517         for (i = 0; i < AF_MAX; i++)
518                 rcu_assign_pointer(nf_ct_l3protos[i],
519                                    &nf_conntrack_l3proto_generic);
520         return 0;
521 }
522 
523 void nf_conntrack_proto_fini(void)
524 {
525         unsigned int i;
526         /* free l3proto protocol tables */
527         for (i = 0; i < PF_MAX; i++)
528                 kfree(nf_ct_protos[i]);
529 }
530 

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