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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 struct nf_conntrack_l4proto *
129 nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
130 {
131         struct nf_conntrack_l4proto *p;
132 
133         rcu_read_lock();
134         p = __nf_ct_l4proto_find(l3num, l4num);
135         if (!try_module_get(p->me))
136                 p = &nf_conntrack_l4proto_generic;
137         rcu_read_unlock();
138 
139         return p;
140 }
141 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
142 
143 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
144 {
145         module_put(p->me);
146 }
147 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
148 
149 static int kill_l3proto(struct nf_conn *i, void *data)
150 {
151         return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
152 }
153 
154 static int kill_l4proto(struct nf_conn *i, void *data)
155 {
156         struct nf_conntrack_l4proto *l4proto;
157         l4proto = (struct nf_conntrack_l4proto *)data;
158         return nf_ct_protonum(i) == l4proto->l4proto &&
159                nf_ct_l3num(i) == l4proto->l3proto;
160 }
161 
162 static struct nf_ip_net *nf_ct_l3proto_net(struct net *net,
163                                            struct nf_conntrack_l3proto *l3proto)
164 {
165         if (l3proto->l3proto == PF_INET)
166                 return &net->ct.nf_ct_proto;
167         else
168                 return NULL;
169 }
170 
171 static int nf_ct_l3proto_register_sysctl(struct net *net,
172                                          struct nf_conntrack_l3proto *l3proto)
173 {
174         int err = 0;
175         struct nf_ip_net *in = nf_ct_l3proto_net(net, l3proto);
176         /* nf_conntrack_l3proto_ipv6 doesn't support sysctl */
177         if (in == NULL)
178                 return 0;
179 
180 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
181         if (in->ctl_table != NULL) {
182                 err = nf_ct_register_sysctl(net,
183                                             &in->ctl_table_header,
184                                             l3proto->ctl_table_path,
185                                             in->ctl_table);
186                 if (err < 0) {
187                         kfree(in->ctl_table);
188                         in->ctl_table = NULL;
189                 }
190         }
191 #endif
192         return err;
193 }
194 
195 static void nf_ct_l3proto_unregister_sysctl(struct net *net,
196                                             struct nf_conntrack_l3proto *l3proto)
197 {
198         struct nf_ip_net *in = nf_ct_l3proto_net(net, l3proto);
199 
200         if (in == NULL)
201                 return;
202 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
203         if (in->ctl_table_header != NULL)
204                 nf_ct_unregister_sysctl(&in->ctl_table_header,
205                                         &in->ctl_table,
206                                         0);
207 #endif
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 int nf_ct_l3proto_pernet_register(struct net *net,
242                                   struct nf_conntrack_l3proto *proto)
243 {
244         int ret = 0;
245 
246         if (proto->init_net) {
247                 ret = proto->init_net(net);
248                 if (ret < 0)
249                         return ret;
250         }
251 
252         return nf_ct_l3proto_register_sysctl(net, proto);
253 }
254 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_register);
255 
256 void nf_ct_l3proto_unregister(struct nf_conntrack_l3proto *proto)
257 {
258         BUG_ON(proto->l3proto >= AF_MAX);
259 
260         mutex_lock(&nf_ct_proto_mutex);
261         BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
262                                          lockdep_is_held(&nf_ct_proto_mutex)
263                                          ) != proto);
264         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
265                            &nf_conntrack_l3proto_generic);
266         mutex_unlock(&nf_ct_proto_mutex);
267 
268         synchronize_rcu();
269 }
270 EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);
271 
272 void nf_ct_l3proto_pernet_unregister(struct net *net,
273                                      struct nf_conntrack_l3proto *proto)
274 {
275         nf_ct_l3proto_unregister_sysctl(net, proto);
276 
277         /* Remove all contrack entries for this protocol */
278         nf_ct_iterate_cleanup(net, kill_l3proto, proto, 0, 0);
279 }
280 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_unregister);
281 
282 static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,
283                                               struct nf_conntrack_l4proto *l4proto)
284 {
285         if (l4proto->get_net_proto) {
286                 /* statically built-in protocols use static per-net */
287                 return l4proto->get_net_proto(net);
288         } else if (l4proto->net_id) {
289                 /* ... and loadable protocols use dynamic per-net */
290                 return net_generic(net, *l4proto->net_id);
291         }
292         return NULL;
293 }
294 
295 static
296 int nf_ct_l4proto_register_sysctl(struct net *net,
297                                   struct nf_proto_net *pn,
298                                   struct nf_conntrack_l4proto *l4proto)
299 {
300         int err = 0;
301 
302 #ifdef CONFIG_SYSCTL
303         if (pn->ctl_table != NULL) {
304                 err = nf_ct_register_sysctl(net,
305                                             &pn->ctl_table_header,
306                                             "net/netfilter",
307                                             pn->ctl_table);
308                 if (err < 0) {
309                         if (!pn->users) {
310                                 kfree(pn->ctl_table);
311                                 pn->ctl_table = NULL;
312                         }
313                 }
314         }
315 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
316         if (l4proto->l3proto != AF_INET6 && pn->ctl_compat_table != NULL) {
317                 if (err < 0) {
318                         nf_ct_kfree_compat_sysctl_table(pn);
319                         goto out;
320                 }
321                 err = nf_ct_register_sysctl(net,
322                                             &pn->ctl_compat_header,
323                                             "net/ipv4/netfilter",
324                                             pn->ctl_compat_table);
325                 if (err == 0)
326                         goto out;
327 
328                 nf_ct_kfree_compat_sysctl_table(pn);
329                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
330                                         &pn->ctl_table,
331                                         pn->users);
332         }
333 out:
334 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
335 #endif /* CONFIG_SYSCTL */
336         return err;
337 }
338 
339 static
340 void nf_ct_l4proto_unregister_sysctl(struct net *net,
341                                      struct nf_proto_net *pn,
342                                      struct nf_conntrack_l4proto *l4proto)
343 {
344 #ifdef CONFIG_SYSCTL
345         if (pn->ctl_table_header != NULL)
346                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
347                                         &pn->ctl_table,
348                                         pn->users);
349 
350 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
351         if (l4proto->l3proto != AF_INET6 && pn->ctl_compat_header != NULL)
352                 nf_ct_unregister_sysctl(&pn->ctl_compat_header,
353                                         &pn->ctl_compat_table,
354                                         0);
355 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
356 #endif /* CONFIG_SYSCTL */
357 }
358 
359 /* FIXME: Allow NULL functions and sub in pointers to generic for
360    them. --RR */
361 int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto)
362 {
363         int ret = 0;
364 
365         if (l4proto->l3proto >= PF_MAX)
366                 return -EBUSY;
367 
368         if ((l4proto->to_nlattr && !l4proto->nlattr_size)
369                 || (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
370                 return -EINVAL;
371 
372         mutex_lock(&nf_ct_proto_mutex);
373         if (!nf_ct_protos[l4proto->l3proto]) {
374                 /* l3proto may be loaded latter. */
375                 struct nf_conntrack_l4proto __rcu **proto_array;
376                 int i;
377 
378                 proto_array = kmalloc(MAX_NF_CT_PROTO *
379                                       sizeof(struct nf_conntrack_l4proto *),
380                                       GFP_KERNEL);
381                 if (proto_array == NULL) {
382                         ret = -ENOMEM;
383                         goto out_unlock;
384                 }
385 
386                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
387                         RCU_INIT_POINTER(proto_array[i], &nf_conntrack_l4proto_generic);
388 
389                 /* Before making proto_array visible to lockless readers,
390                  * we must make sure its content is committed to memory.
391                  */
392                 smp_wmb();
393 
394                 nf_ct_protos[l4proto->l3proto] = proto_array;
395         } else if (rcu_dereference_protected(
396                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
397                         lockdep_is_held(&nf_ct_proto_mutex)
398                         ) != &nf_conntrack_l4proto_generic) {
399                 ret = -EBUSY;
400                 goto out_unlock;
401         }
402 
403         l4proto->nla_size = 0;
404         if (l4proto->nlattr_size)
405                 l4proto->nla_size += l4proto->nlattr_size();
406         if (l4proto->nlattr_tuple_size)
407                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
408 
409         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
410                            l4proto);
411 out_unlock:
412         mutex_unlock(&nf_ct_proto_mutex);
413         return ret;
414 }
415 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);
416 
417 int nf_ct_l4proto_pernet_register(struct net *net,
418                                   struct nf_conntrack_l4proto *l4proto)
419 {
420         int ret = 0;
421         struct nf_proto_net *pn = NULL;
422 
423         if (l4proto->init_net) {
424                 ret = l4proto->init_net(net, l4proto->l3proto);
425                 if (ret < 0)
426                         goto out;
427         }
428 
429         pn = nf_ct_l4proto_net(net, l4proto);
430         if (pn == NULL)
431                 goto out;
432 
433         ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
434         if (ret < 0)
435                 goto out;
436 
437         pn->users++;
438 out:
439         return ret;
440 }
441 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);
442 
443 void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
444 {
445         BUG_ON(l4proto->l3proto >= PF_MAX);
446 
447         mutex_lock(&nf_ct_proto_mutex);
448         BUG_ON(rcu_dereference_protected(
449                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
450                         lockdep_is_held(&nf_ct_proto_mutex)
451                         ) != l4proto);
452         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
453                            &nf_conntrack_l4proto_generic);
454         mutex_unlock(&nf_ct_proto_mutex);
455 
456         synchronize_rcu();
457 }
458 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);
459 
460 void nf_ct_l4proto_pernet_unregister(struct net *net,
461                                      struct nf_conntrack_l4proto *l4proto)
462 {
463         struct nf_proto_net *pn = NULL;
464 
465         pn = nf_ct_l4proto_net(net, l4proto);
466         if (pn == NULL)
467                 return;
468 
469         pn->users--;
470         nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
471 
472         /* Remove all contrack entries for this protocol */
473         nf_ct_iterate_cleanup(net, kill_l4proto, l4proto, 0, 0);
474 }
475 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);
476 
477 int nf_conntrack_proto_pernet_init(struct net *net)
478 {
479         int err;
480         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
481                                         &nf_conntrack_l4proto_generic);
482 
483         err = nf_conntrack_l4proto_generic.init_net(net,
484                                         nf_conntrack_l4proto_generic.l3proto);
485         if (err < 0)
486                 return err;
487         err = nf_ct_l4proto_register_sysctl(net,
488                                             pn,
489                                             &nf_conntrack_l4proto_generic);
490         if (err < 0)
491                 return err;
492 
493         pn->users++;
494         return 0;
495 }
496 
497 void nf_conntrack_proto_pernet_fini(struct net *net)
498 {
499         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
500                                         &nf_conntrack_l4proto_generic);
501 
502         pn->users--;
503         nf_ct_l4proto_unregister_sysctl(net,
504                                         pn,
505                                         &nf_conntrack_l4proto_generic);
506 }
507 
508 int nf_conntrack_proto_init(void)
509 {
510         unsigned int i;
511         for (i = 0; i < AF_MAX; i++)
512                 rcu_assign_pointer(nf_ct_l3protos[i],
513                                    &nf_conntrack_l3proto_generic);
514         return 0;
515 }
516 
517 void nf_conntrack_proto_fini(void)
518 {
519         unsigned int i;
520         /* free l3proto protocol tables */
521         for (i = 0; i < PF_MAX; i++)
522                 kfree(nf_ct_protos[i]);
523 }
524 

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