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 *
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 #include <linux/rtnetlink.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 ctl_table_header ** header,struct ctl_path * path,struct ctl_table * table,unsigned int * users)39 nf_ct_register_sysctl(struct ctl_table_header **header, struct ctl_path *path,
40 struct ctl_table *table, unsigned int *users)
41 {
42 if (*header == NULL) {
43 *header = register_sysctl_paths(path, table);
44 if (*header == NULL)
45 return -ENOMEM;
46 }
47 if (users != NULL)
48 (*users)++;
49 return 0;
50 }
51
52 static void
nf_ct_unregister_sysctl(struct ctl_table_header ** header,struct ctl_table * table,unsigned int * users)53 nf_ct_unregister_sysctl(struct ctl_table_header **header,
54 struct ctl_table *table, unsigned int *users)
55 {
56 if (users != NULL && --*users > 0)
57 return;
58
59 unregister_sysctl_table(*header);
60 *header = NULL;
61 }
62 #endif
63
64 struct nf_conntrack_l4proto *
__nf_ct_l4proto_find(u_int16_t l3proto,u_int8_t l4proto)65 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
66 {
67 if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
68 return &nf_conntrack_l4proto_generic;
69
70 return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
71 }
72 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
73
74 /* this is guaranteed to always return a valid protocol helper, since
75 * it falls back to generic_protocol */
76 struct nf_conntrack_l3proto *
nf_ct_l3proto_find_get(u_int16_t l3proto)77 nf_ct_l3proto_find_get(u_int16_t l3proto)
78 {
79 struct nf_conntrack_l3proto *p;
80
81 rcu_read_lock();
82 p = __nf_ct_l3proto_find(l3proto);
83 if (!try_module_get(p->me))
84 p = &nf_conntrack_l3proto_generic;
85 rcu_read_unlock();
86
87 return p;
88 }
89 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
90
nf_ct_l3proto_put(struct nf_conntrack_l3proto * p)91 void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
92 {
93 module_put(p->me);
94 }
95 EXPORT_SYMBOL_GPL(nf_ct_l3proto_put);
96
97 int
nf_ct_l3proto_try_module_get(unsigned short l3proto)98 nf_ct_l3proto_try_module_get(unsigned short l3proto)
99 {
100 int ret;
101 struct nf_conntrack_l3proto *p;
102
103 retry: p = nf_ct_l3proto_find_get(l3proto);
104 if (p == &nf_conntrack_l3proto_generic) {
105 ret = request_module("nf_conntrack-%d", l3proto);
106 if (!ret)
107 goto retry;
108
109 return -EPROTOTYPE;
110 }
111
112 return 0;
113 }
114 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
115
nf_ct_l3proto_module_put(unsigned short l3proto)116 void nf_ct_l3proto_module_put(unsigned short l3proto)
117 {
118 struct nf_conntrack_l3proto *p;
119
120 /* rcu_read_lock not necessary since the caller holds a reference, but
121 * taken anyways to avoid lockdep warnings in __nf_ct_l3proto_find()
122 */
123 rcu_read_lock();
124 p = __nf_ct_l3proto_find(l3proto);
125 module_put(p->me);
126 rcu_read_unlock();
127 }
128 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
129
130 struct nf_conntrack_l4proto *
nf_ct_l4proto_find_get(u_int16_t l3num,u_int8_t l4num)131 nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
132 {
133 struct nf_conntrack_l4proto *p;
134
135 rcu_read_lock();
136 p = __nf_ct_l4proto_find(l3num, l4num);
137 if (!try_module_get(p->me))
138 p = &nf_conntrack_l4proto_generic;
139 rcu_read_unlock();
140
141 return p;
142 }
143 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
144
nf_ct_l4proto_put(struct nf_conntrack_l4proto * p)145 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
146 {
147 module_put(p->me);
148 }
149 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
150
kill_l3proto(struct nf_conn * i,void * data)151 static int kill_l3proto(struct nf_conn *i, void *data)
152 {
153 return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
154 }
155
kill_l4proto(struct nf_conn * i,void * data)156 static int kill_l4proto(struct nf_conn *i, void *data)
157 {
158 struct nf_conntrack_l4proto *l4proto;
159 l4proto = (struct nf_conntrack_l4proto *)data;
160 return nf_ct_protonum(i) == l4proto->l4proto &&
161 nf_ct_l3num(i) == l4proto->l3proto;
162 }
163
nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto * l3proto)164 static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
165 {
166 int err = 0;
167
168 #ifdef CONFIG_SYSCTL
169 if (l3proto->ctl_table != NULL) {
170 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
171 l3proto->ctl_table_path,
172 l3proto->ctl_table, NULL);
173 }
174 #endif
175 return err;
176 }
177
nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto * l3proto)178 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
179 {
180 #ifdef CONFIG_SYSCTL
181 if (l3proto->ctl_table_header != NULL)
182 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
183 l3proto->ctl_table, NULL);
184 #endif
185 }
186
nf_conntrack_l3proto_register(struct nf_conntrack_l3proto * proto)187 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
188 {
189 int ret = 0;
190 struct nf_conntrack_l3proto *old;
191
192 if (proto->l3proto >= AF_MAX)
193 return -EBUSY;
194
195 if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
196 return -EINVAL;
197
198 mutex_lock(&nf_ct_proto_mutex);
199 old = rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
200 lockdep_is_held(&nf_ct_proto_mutex));
201 if (old != &nf_conntrack_l3proto_generic) {
202 ret = -EBUSY;
203 goto out_unlock;
204 }
205
206 ret = nf_ct_l3proto_register_sysctl(proto);
207 if (ret < 0)
208 goto out_unlock;
209
210 if (proto->nlattr_tuple_size)
211 proto->nla_size = 3 * proto->nlattr_tuple_size();
212
213 rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
214
215 out_unlock:
216 mutex_unlock(&nf_ct_proto_mutex);
217 return ret;
218 }
219 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
220
nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto * proto)221 void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
222 {
223 struct net *net;
224
225 BUG_ON(proto->l3proto >= AF_MAX);
226
227 mutex_lock(&nf_ct_proto_mutex);
228 BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
229 lockdep_is_held(&nf_ct_proto_mutex)
230 ) != proto);
231 rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
232 &nf_conntrack_l3proto_generic);
233 nf_ct_l3proto_unregister_sysctl(proto);
234 mutex_unlock(&nf_ct_proto_mutex);
235
236 synchronize_rcu();
237
238 /* Remove all contrack entries for this protocol */
239 rtnl_lock();
240 for_each_net(net)
241 nf_ct_iterate_cleanup(net, kill_l3proto, proto);
242 rtnl_unlock();
243 }
244 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
245
nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto * l4proto)246 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
247 {
248 int err = 0;
249
250 #ifdef CONFIG_SYSCTL
251 if (l4proto->ctl_table != NULL) {
252 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
253 nf_net_netfilter_sysctl_path,
254 l4proto->ctl_table,
255 l4proto->ctl_table_users);
256 if (err < 0)
257 goto out;
258 }
259 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
260 if (l4proto->ctl_compat_table != NULL) {
261 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
262 nf_net_ipv4_netfilter_sysctl_path,
263 l4proto->ctl_compat_table, NULL);
264 if (err == 0)
265 goto out;
266 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
267 l4proto->ctl_table,
268 l4proto->ctl_table_users);
269 }
270 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
271 out:
272 #endif /* CONFIG_SYSCTL */
273 return err;
274 }
275
nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto * l4proto)276 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
277 {
278 #ifdef CONFIG_SYSCTL
279 if (l4proto->ctl_table_header != NULL &&
280 *l4proto->ctl_table_header != NULL)
281 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
282 l4proto->ctl_table,
283 l4proto->ctl_table_users);
284 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
285 if (l4proto->ctl_compat_table_header != NULL)
286 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
287 l4proto->ctl_compat_table, NULL);
288 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
289 #endif /* CONFIG_SYSCTL */
290 }
291
292 /* FIXME: Allow NULL functions and sub in pointers to generic for
293 them. --RR */
nf_conntrack_l4proto_register(struct nf_conntrack_l4proto * l4proto)294 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
295 {
296 int ret = 0;
297
298 if (l4proto->l3proto >= PF_MAX)
299 return -EBUSY;
300
301 if ((l4proto->to_nlattr && !l4proto->nlattr_size)
302 || (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
303 return -EINVAL;
304
305 mutex_lock(&nf_ct_proto_mutex);
306 if (!nf_ct_protos[l4proto->l3proto]) {
307 /* l3proto may be loaded latter. */
308 struct nf_conntrack_l4proto __rcu **proto_array;
309 int i;
310
311 proto_array = kmalloc(MAX_NF_CT_PROTO *
312 sizeof(struct nf_conntrack_l4proto *),
313 GFP_KERNEL);
314 if (proto_array == NULL) {
315 ret = -ENOMEM;
316 goto out_unlock;
317 }
318
319 for (i = 0; i < MAX_NF_CT_PROTO; i++)
320 RCU_INIT_POINTER(proto_array[i], &nf_conntrack_l4proto_generic);
321
322 /* Before making proto_array visible to lockless readers,
323 * we must make sure its content is committed to memory.
324 */
325 smp_wmb();
326
327 nf_ct_protos[l4proto->l3proto] = proto_array;
328 } else if (rcu_dereference_protected(
329 nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
330 lockdep_is_held(&nf_ct_proto_mutex)
331 ) != &nf_conntrack_l4proto_generic) {
332 ret = -EBUSY;
333 goto out_unlock;
334 }
335
336 ret = nf_ct_l4proto_register_sysctl(l4proto);
337 if (ret < 0)
338 goto out_unlock;
339
340 l4proto->nla_size = 0;
341 if (l4proto->nlattr_size)
342 l4proto->nla_size += l4proto->nlattr_size();
343 if (l4proto->nlattr_tuple_size)
344 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
345
346 rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
347 l4proto);
348
349 out_unlock:
350 mutex_unlock(&nf_ct_proto_mutex);
351 return ret;
352 }
353 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
354
nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto * l4proto)355 void nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
356 {
357 struct net *net;
358
359 BUG_ON(l4proto->l3proto >= PF_MAX);
360
361 mutex_lock(&nf_ct_proto_mutex);
362 BUG_ON(rcu_dereference_protected(
363 nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
364 lockdep_is_held(&nf_ct_proto_mutex)
365 ) != l4proto);
366 rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
367 &nf_conntrack_l4proto_generic);
368 nf_ct_l4proto_unregister_sysctl(l4proto);
369 mutex_unlock(&nf_ct_proto_mutex);
370
371 synchronize_rcu();
372
373 /* Remove all contrack entries for this protocol */
374 rtnl_lock();
375 for_each_net(net)
376 nf_ct_iterate_cleanup(net, kill_l4proto, l4proto);
377 rtnl_unlock();
378 }
379 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);
380
nf_conntrack_proto_init(void)381 int nf_conntrack_proto_init(void)
382 {
383 unsigned int i;
384 int err;
385
386 err = nf_ct_l4proto_register_sysctl(&nf_conntrack_l4proto_generic);
387 if (err < 0)
388 return err;
389
390 for (i = 0; i < AF_MAX; i++)
391 rcu_assign_pointer(nf_ct_l3protos[i],
392 &nf_conntrack_l3proto_generic);
393 return 0;
394 }
395
nf_conntrack_proto_fini(void)396 void nf_conntrack_proto_fini(void)
397 {
398 unsigned int i;
399
400 nf_ct_l4proto_unregister_sysctl(&nf_conntrack_l4proto_generic);
401
402 /* free l3proto protocol tables */
403 for (i = 0; i < PF_MAX; i++)
404 kfree(nf_ct_protos[i]);
405 }
406