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
nf_ct_register_sysctl(struct net * net,struct ctl_table_header ** header,const char * path,struct ctl_table * table)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
nf_ct_unregister_sysctl(struct ctl_table_header ** header,struct ctl_table ** table,unsigned int users)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 *
__nf_ct_l4proto_find(u_int16_t l3proto,u_int8_t 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 *
nf_ct_l3proto_find_get(u_int16_t 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
nf_ct_l3proto_try_module_get(unsigned short l3proto)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
nf_ct_l3proto_module_put(unsigned short l3proto)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 *
nf_ct_l4proto_find_get(u_int16_t l3num,u_int8_t l4num)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
nf_ct_l4proto_put(struct nf_conntrack_l4proto * p)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
kill_l3proto(struct nf_conn * i,void * data)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
kill_l4proto(struct nf_conn * i,void * data)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
nf_ct_l3proto_net(struct net * net,struct nf_conntrack_l3proto * l3proto)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
nf_ct_l3proto_register_sysctl(struct net * net,struct nf_conntrack_l3proto * l3proto)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
nf_ct_l3proto_unregister_sysctl(struct net * net,struct nf_conntrack_l3proto * l3proto)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
nf_ct_l3proto_register(struct nf_conntrack_l3proto * proto)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
nf_ct_l3proto_pernet_register(struct net * net,struct nf_conntrack_l3proto * proto)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
nf_ct_l3proto_unregister(struct nf_conntrack_l3proto * proto)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
nf_ct_l3proto_pernet_unregister(struct net * net,struct nf_conntrack_l3proto * proto)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
nf_ct_l4proto_net(struct net * net,struct nf_conntrack_l4proto * l4proto)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
nf_ct_l4proto_register_sysctl(struct net * net,struct nf_proto_net * pn,struct nf_conntrack_l4proto * l4proto)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
nf_ct_l4proto_unregister_sysctl(struct net * net,struct nf_proto_net * pn,struct nf_conntrack_l4proto * l4proto)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 */
nf_ct_l4proto_register(struct nf_conntrack_l4proto * l4proto)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
nf_ct_l4proto_pernet_register(struct net * net,struct nf_conntrack_l4proto * l4proto)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
nf_ct_l4proto_unregister(struct nf_conntrack_l4proto * l4proto)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
nf_ct_l4proto_pernet_unregister(struct net * net,struct nf_conntrack_l4proto * l4proto)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
nf_conntrack_proto_pernet_init(struct net * net)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
nf_conntrack_proto_pernet_fini(struct net * net)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
nf_conntrack_proto_init(void)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
nf_conntrack_proto_fini(void)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