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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 <[email protected]>
5  * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  */
11 
12 #include <linux/types.h>
13 #include <linux/netfilter.h>
14 #include <linux/module.h>
15 #include <linux/slab.h>
16 #include <linux/mutex.h>
17 #include <linux/vmalloc.h>
18 #include <linux/stddef.h>
19 #include <linux/err.h>
20 #include <linux/percpu.h>
21 #include <linux/notifier.h>
22 #include <linux/kernel.h>
23 #include <linux/netdevice.h>
24 
25 #include <net/netfilter/nf_conntrack.h>
26 #include <net/netfilter/nf_conntrack_l3proto.h>
27 #include <net/netfilter/nf_conntrack_l4proto.h>
28 #include <net/netfilter/nf_conntrack_core.h>
29 
30 static struct nf_conntrack_l4proto __rcu **nf_ct_protos[PF_MAX] __read_mostly;
31 struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[AF_MAX] __read_mostly;
32 EXPORT_SYMBOL_GPL(nf_ct_l3protos);
33 
34 static DEFINE_MUTEX(nf_ct_proto_mutex);
35 
36 #ifdef CONFIG_SYSCTL
37 static int
38 nf_ct_register_sysctl(struct net *net,
39  struct ctl_table_header **header,
40  const char *path,
41  struct ctl_table *table)
42 {
43  if (*header == NULL) {
44  *header = register_net_sysctl(net, path, table);
45  if (*header == NULL)
46  return -ENOMEM;
47  }
48 
49  return 0;
50 }
51 
52 static void
53 nf_ct_unregister_sysctl(struct ctl_table_header **header,
54  struct ctl_table **table,
55  unsigned int users)
56 {
57  if (users > 0)
58  return;
59 
60  unregister_net_sysctl_table(*header);
61  kfree(*table);
62  *header = NULL;
63  *table = NULL;
64 }
65 #endif
66 
67 struct nf_conntrack_l4proto *
68 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
69 {
70  if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
71  return &nf_conntrack_l4proto_generic;
72 
73  return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
74 }
75 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
76 
77 /* this is guaranteed to always return a valid protocol helper, since
78  * it falls back to generic_protocol */
79 struct nf_conntrack_l3proto *
80 nf_ct_l3proto_find_get(u_int16_t l3proto)
81 {
82  struct nf_conntrack_l3proto *p;
83 
84  rcu_read_lock();
85  p = __nf_ct_l3proto_find(l3proto);
86  if (!try_module_get(p->me))
87  p = &nf_conntrack_l3proto_generic;
88  rcu_read_unlock();
89 
90  return p;
91 }
92 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
93 
94 void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
95 {
96  module_put(p->me);
97 }
98 EXPORT_SYMBOL_GPL(nf_ct_l3proto_put);
99 
100 int
101 nf_ct_l3proto_try_module_get(unsigned short l3proto)
102 {
103  int ret;
104  struct nf_conntrack_l3proto *p;
105 
106 retry: p = nf_ct_l3proto_find_get(l3proto);
107  if (p == &nf_conntrack_l3proto_generic) {
108  ret = request_module("nf_conntrack-%d", l3proto);
109  if (!ret)
110  goto retry;
111 
112  return -EPROTOTYPE;
113  }
114 
115  return 0;
116 }
117 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
118 
119 void nf_ct_l3proto_module_put(unsigned short l3proto)
120 {
121  struct nf_conntrack_l3proto *p;
122 
123  /* rcu_read_lock not necessary since the caller holds a reference, but
124  * taken anyways to avoid lockdep warnings in __nf_ct_l3proto_find()
125  */
126  rcu_read_lock();
127  p = __nf_ct_l3proto_find(l3proto);
128  module_put(p->me);
129  rcu_read_unlock();
130 }
131 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
132 
133 struct nf_conntrack_l4proto *
134 nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
135 {
136  struct nf_conntrack_l4proto *p;
137 
138  rcu_read_lock();
139  p = __nf_ct_l4proto_find(l3num, l4num);
140  if (!try_module_get(p->me))
141  p = &nf_conntrack_l4proto_generic;
142  rcu_read_unlock();
143 
144  return p;
145 }
146 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
147 
148 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
149 {
150  module_put(p->me);
151 }
152 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
153 
154 static int kill_l3proto(struct nf_conn *i, void *data)
155 {
156  return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
157 }
158 
159 static int kill_l4proto(struct nf_conn *i, void *data)
160 {
161  struct nf_conntrack_l4proto *l4proto;
162  l4proto = (struct nf_conntrack_l4proto *)data;
163  return nf_ct_protonum(i) == l4proto->l4proto &&
164  nf_ct_l3num(i) == l4proto->l3proto;
165 }
166 
167 static struct nf_ip_net *nf_ct_l3proto_net(struct net *net,
168  struct nf_conntrack_l3proto *l3proto)
169 {
170  if (l3proto->l3proto == PF_INET)
171  return &net->ct.nf_ct_proto;
172  else
173  return NULL;
174 }
175 
176 static int nf_ct_l3proto_register_sysctl(struct net *net,
177  struct nf_conntrack_l3proto *l3proto)
178 {
179  int err = 0;
180  struct nf_ip_net *in = nf_ct_l3proto_net(net, l3proto);
181  /* nf_conntrack_l3proto_ipv6 doesn't support sysctl */
182  if (in == NULL)
183  return 0;
184 
185 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
186  if (in->ctl_table != NULL) {
187  err = nf_ct_register_sysctl(net,
188  &in->ctl_table_header,
189  l3proto->ctl_table_path,
190  in->ctl_table);
191  if (err < 0) {
192  kfree(in->ctl_table);
193  in->ctl_table = NULL;
194  }
195  }
196 #endif
197  return err;
198 }
199 
200 static void nf_ct_l3proto_unregister_sysctl(struct net *net,
201  struct nf_conntrack_l3proto *l3proto)
202 {
203  struct nf_ip_net *in = nf_ct_l3proto_net(net, l3proto);
204 
205  if (in == NULL)
206  return;
207 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
208  if (in->ctl_table_header != NULL)
209  nf_ct_unregister_sysctl(&in->ctl_table_header,
210  &in->ctl_table,
211  0);
212 #endif
213 }
214 
215 static int
216 nf_conntrack_l3proto_register_net(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 
246 int nf_conntrack_l3proto_register(struct net *net,
247  struct nf_conntrack_l3proto *proto)
248 {
249  int ret = 0;
250 
251  if (proto->init_net) {
252  ret = proto->init_net(net);
253  if (ret < 0)
254  return ret;
255  }
256 
257  ret = nf_ct_l3proto_register_sysctl(net, proto);
258  if (ret < 0)
259  return ret;
260 
261  if (net == &init_net) {
262  ret = nf_conntrack_l3proto_register_net(proto);
263  if (ret < 0)
264  nf_ct_l3proto_unregister_sysctl(net, proto);
265  }
266 
267  return ret;
268 }
269 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
270 
271 static void
272 nf_conntrack_l3proto_unregister_net(struct nf_conntrack_l3proto *proto)
273 {
274  BUG_ON(proto->l3proto >= AF_MAX);
275 
276  mutex_lock(&nf_ct_proto_mutex);
277  BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
278  lockdep_is_held(&nf_ct_proto_mutex)
279  ) != proto);
280  rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
281  &nf_conntrack_l3proto_generic);
282  mutex_unlock(&nf_ct_proto_mutex);
283 
284  synchronize_rcu();
285 }
286 
287 void nf_conntrack_l3proto_unregister(struct net *net,
288  struct nf_conntrack_l3proto *proto)
289 {
290  if (net == &init_net)
291  nf_conntrack_l3proto_unregister_net(proto);
292 
293  nf_ct_l3proto_unregister_sysctl(net, proto);
294 
295  /* Remove all contrack entries for this protocol */
296  nf_ct_iterate_cleanup(net, kill_l3proto, proto);
297 }
298 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
299 
300 static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,
301  struct nf_conntrack_l4proto *l4proto)
302 {
303  if (l4proto->get_net_proto) {
304  /* statically built-in protocols use static per-net */
305  return l4proto->get_net_proto(net);
306  } else if (l4proto->net_id) {
307  /* ... and loadable protocols use dynamic per-net */
308  return net_generic(net, *l4proto->net_id);
309  }
310  return NULL;
311 }
312 
313 static
314 int nf_ct_l4proto_register_sysctl(struct net *net,
315  struct nf_proto_net *pn,
316  struct nf_conntrack_l4proto *l4proto)
317 {
318  int err = 0;
319 
320 #ifdef CONFIG_SYSCTL
321  if (pn->ctl_table != NULL) {
322  err = nf_ct_register_sysctl(net,
323  &pn->ctl_table_header,
324  "net/netfilter",
325  pn->ctl_table);
326  if (err < 0) {
327  if (!pn->users) {
328  kfree(pn->ctl_table);
329  pn->ctl_table = NULL;
330  }
331  }
332  }
333 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
334  if (l4proto->l3proto != AF_INET6 && pn->ctl_compat_table != NULL) {
335  if (err < 0) {
336  nf_ct_kfree_compat_sysctl_table(pn);
337  goto out;
338  }
339  err = nf_ct_register_sysctl(net,
340  &pn->ctl_compat_header,
341  "net/ipv4/netfilter",
342  pn->ctl_compat_table);
343  if (err == 0)
344  goto out;
345 
346  nf_ct_kfree_compat_sysctl_table(pn);
347  nf_ct_unregister_sysctl(&pn->ctl_table_header,
348  &pn->ctl_table,
349  pn->users);
350  }
351 out:
352 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
353 #endif /* CONFIG_SYSCTL */
354  return err;
355 }
356 
357 static
358 void nf_ct_l4proto_unregister_sysctl(struct net *net,
359  struct nf_proto_net *pn,
360  struct nf_conntrack_l4proto *l4proto)
361 {
362 #ifdef CONFIG_SYSCTL
363  if (pn->ctl_table_header != NULL)
364  nf_ct_unregister_sysctl(&pn->ctl_table_header,
365  &pn->ctl_table,
366  pn->users);
367 
368 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
369  if (l4proto->l3proto != AF_INET6 && pn->ctl_compat_header != NULL)
370  nf_ct_unregister_sysctl(&pn->ctl_compat_header,
371  &pn->ctl_compat_table,
372  0);
373 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
374 #endif /* CONFIG_SYSCTL */
375 }
376 
377 /* FIXME: Allow NULL functions and sub in pointers to generic for
378  them. --RR */
379 static int
380 nf_conntrack_l4proto_register_net(struct nf_conntrack_l4proto *l4proto)
381 {
382  int ret = 0;
383 
384  if (l4proto->l3proto >= PF_MAX)
385  return -EBUSY;
386 
387  if ((l4proto->to_nlattr && !l4proto->nlattr_size)
388  || (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
389  return -EINVAL;
390 
391  mutex_lock(&nf_ct_proto_mutex);
392  if (!nf_ct_protos[l4proto->l3proto]) {
393  /* l3proto may be loaded latter. */
394  struct nf_conntrack_l4proto __rcu **proto_array;
395  int i;
396 
397  proto_array = kmalloc(MAX_NF_CT_PROTO *
398  sizeof(struct nf_conntrack_l4proto *),
399  GFP_KERNEL);
400  if (proto_array == NULL) {
401  ret = -ENOMEM;
402  goto out_unlock;
403  }
404 
405  for (i = 0; i < MAX_NF_CT_PROTO; i++)
406  RCU_INIT_POINTER(proto_array[i], &nf_conntrack_l4proto_generic);
407 
408  /* Before making proto_array visible to lockless readers,
409  * we must make sure its content is committed to memory.
410  */
411  smp_wmb();
412 
413  nf_ct_protos[l4proto->l3proto] = proto_array;
414  } else if (rcu_dereference_protected(
415  nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
416  lockdep_is_held(&nf_ct_proto_mutex)
417  ) != &nf_conntrack_l4proto_generic) {
418  ret = -EBUSY;
419  goto out_unlock;
420  }
421 
422  l4proto->nla_size = 0;
423  if (l4proto->nlattr_size)
424  l4proto->nla_size += l4proto->nlattr_size();
425  if (l4proto->nlattr_tuple_size)
426  l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
427 
428  rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
429  l4proto);
430 out_unlock:
431  mutex_unlock(&nf_ct_proto_mutex);
432  return ret;
433 }
434 
435 int nf_conntrack_l4proto_register(struct net *net,
436  struct nf_conntrack_l4proto *l4proto)
437 {
438  int ret = 0;
439  struct nf_proto_net *pn = NULL;
440 
441  if (l4proto->init_net) {
442  ret = l4proto->init_net(net, l4proto->l3proto);
443  if (ret < 0)
444  goto out;
445  }
446 
447  pn = nf_ct_l4proto_net(net, l4proto);
448  if (pn == NULL)
449  goto out;
450 
451  ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
452  if (ret < 0)
453  goto out;
454 
455  if (net == &init_net) {
456  ret = nf_conntrack_l4proto_register_net(l4proto);
457  if (ret < 0) {
458  nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
459  goto out;
460  }
461  }
462 
463  pn->users++;
464 out:
465  return ret;
466 }
467 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
468 
469 static void
470 nf_conntrack_l4proto_unregister_net(struct nf_conntrack_l4proto *l4proto)
471 {
472  BUG_ON(l4proto->l3proto >= PF_MAX);
473 
474  mutex_lock(&nf_ct_proto_mutex);
475  BUG_ON(rcu_dereference_protected(
476  nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
477  lockdep_is_held(&nf_ct_proto_mutex)
478  ) != l4proto);
479  rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
480  &nf_conntrack_l4proto_generic);
481  mutex_unlock(&nf_ct_proto_mutex);
482 
483  synchronize_rcu();
484 }
485 
486 void nf_conntrack_l4proto_unregister(struct net *net,
487  struct nf_conntrack_l4proto *l4proto)
488 {
489  struct nf_proto_net *pn = NULL;
490 
491  if (net == &init_net)
492  nf_conntrack_l4proto_unregister_net(l4proto);
493 
494  pn = nf_ct_l4proto_net(net, l4proto);
495  if (pn == NULL)
496  return;
497 
498  pn->users--;
499  nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
500 
501  /* Remove all contrack entries for this protocol */
502  nf_ct_iterate_cleanup(net, kill_l4proto, l4proto);
503 }
504 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);
505 
506 int nf_conntrack_proto_init(struct net *net)
507 {
508  unsigned int i;
509  int err;
510  struct nf_proto_net *pn = nf_ct_l4proto_net(net,
511  &nf_conntrack_l4proto_generic);
512 
513  err = nf_conntrack_l4proto_generic.init_net(net,
514  nf_conntrack_l4proto_generic.l3proto);
515  if (err < 0)
516  return err;
517  err = nf_ct_l4proto_register_sysctl(net,
518  pn,
519  &nf_conntrack_l4proto_generic);
520  if (err < 0)
521  return err;
522 
523  if (net == &init_net) {
524  for (i = 0; i < AF_MAX; i++)
525  rcu_assign_pointer(nf_ct_l3protos[i],
526  &nf_conntrack_l3proto_generic);
527  }
528 
529  pn->users++;
530  return 0;
531 }
532 
533 void nf_conntrack_proto_fini(struct net *net)
534 {
535  unsigned int i;
536  struct nf_proto_net *pn = nf_ct_l4proto_net(net,
537  &nf_conntrack_l4proto_generic);
538 
539  pn->users--;
540  nf_ct_l4proto_unregister_sysctl(net,
541  pn,
542  &nf_conntrack_l4proto_generic);
543  if (net == &init_net) {
544  /* free l3proto protocol tables */
545  for (i = 0; i < PF_MAX; i++)
546  kfree(nf_ct_protos[i]);
547  }
548 }
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