[NETFILTER]: Use the ctl paths instead of hand-made analogue
[linux-2.6.git] / net / netfilter / nf_conntrack_proto.c
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/mutex.h>
16 #include <linux/skbuff.h>
17 #include <linux/vmalloc.h>
18 #include <linux/stddef.h>
19 #include <linux/err.h>
20 #include <linux/percpu.h>
21 #include <linux/moduleparam.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 **nf_ct_protos[PF_MAX] __read_mostly;
32 struct nf_conntrack_l3proto *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 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
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 *
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_l4proto *
77 nf_ct_l4proto_find_get(u_int16_t l3proto, u_int8_t l4proto)
78 {
79         struct nf_conntrack_l4proto *p;
80
81         rcu_read_lock();
82         p = __nf_ct_l4proto_find(l3proto, l4proto);
83         if (!try_module_get(p->me))
84                 p = &nf_conntrack_l4proto_generic;
85         rcu_read_unlock();
86
87         return p;
88 }
89 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
90
91 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
92 {
93         module_put(p->me);
94 }
95 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
96
97 struct nf_conntrack_l3proto *
98 nf_ct_l3proto_find_get(u_int16_t l3proto)
99 {
100         struct nf_conntrack_l3proto *p;
101
102         rcu_read_lock();
103         p = __nf_ct_l3proto_find(l3proto);
104         if (!try_module_get(p->me))
105                 p = &nf_conntrack_l3proto_generic;
106         rcu_read_unlock();
107
108         return p;
109 }
110 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
111
112 void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
113 {
114         module_put(p->me);
115 }
116 EXPORT_SYMBOL_GPL(nf_ct_l3proto_put);
117
118 int
119 nf_ct_l3proto_try_module_get(unsigned short l3proto)
120 {
121         int ret;
122         struct nf_conntrack_l3proto *p;
123
124 retry:  p = nf_ct_l3proto_find_get(l3proto);
125         if (p == &nf_conntrack_l3proto_generic) {
126                 ret = request_module("nf_conntrack-%d", l3proto);
127                 if (!ret)
128                         goto retry;
129
130                 return -EPROTOTYPE;
131         }
132
133         return 0;
134 }
135 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
136
137 void nf_ct_l3proto_module_put(unsigned short l3proto)
138 {
139         struct nf_conntrack_l3proto *p;
140
141         /* rcu_read_lock not necessary since the caller holds a reference */
142         p = __nf_ct_l3proto_find(l3proto);
143         module_put(p->me);
144 }
145 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
146
147 static int kill_l3proto(struct nf_conn *i, void *data)
148 {
149         return (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num ==
150                         ((struct nf_conntrack_l3proto *)data)->l3proto);
151 }
152
153 static int kill_l4proto(struct nf_conn *i, void *data)
154 {
155         struct nf_conntrack_l4proto *l4proto;
156         l4proto = (struct nf_conntrack_l4proto *)data;
157         return (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum ==
158                         l4proto->l4proto) &&
159                (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num ==
160                         l4proto->l3proto);
161 }
162
163 static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
164 {
165         int err = 0;
166
167 #ifdef CONFIG_SYSCTL
168         if (l3proto->ctl_table != NULL) {
169                 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
170                                             l3proto->ctl_table_path,
171                                             l3proto->ctl_table, NULL);
172         }
173 #endif
174         return err;
175 }
176
177 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
178 {
179 #ifdef CONFIG_SYSCTL
180         if (l3proto->ctl_table_header != NULL)
181                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
182                                         l3proto->ctl_table, NULL);
183 #endif
184 }
185
186 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
187 {
188         int ret = 0;
189
190         if (proto->l3proto >= AF_MAX)
191                 return -EBUSY;
192
193         mutex_lock(&nf_ct_proto_mutex);
194         if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
195                 ret = -EBUSY;
196                 goto out_unlock;
197         }
198
199         ret = nf_ct_l3proto_register_sysctl(proto);
200         if (ret < 0)
201                 goto out_unlock;
202
203         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
204
205 out_unlock:
206         mutex_unlock(&nf_ct_proto_mutex);
207         return ret;
208 }
209 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
210
211 void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
212 {
213         BUG_ON(proto->l3proto >= AF_MAX);
214
215         mutex_lock(&nf_ct_proto_mutex);
216         BUG_ON(nf_ct_l3protos[proto->l3proto] != proto);
217         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
218                            &nf_conntrack_l3proto_generic);
219         nf_ct_l3proto_unregister_sysctl(proto);
220         mutex_unlock(&nf_ct_proto_mutex);
221
222         synchronize_rcu();
223
224         /* Remove all contrack entries for this protocol */
225         nf_ct_iterate_cleanup(kill_l3proto, proto);
226 }
227 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
228
229 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
230 {
231         int err = 0;
232
233 #ifdef CONFIG_SYSCTL
234         if (l4proto->ctl_table != NULL) {
235                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
236                                             nf_net_netfilter_sysctl_path,
237                                             l4proto->ctl_table,
238                                             l4proto->ctl_table_users);
239                 if (err < 0)
240                         goto out;
241         }
242 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
243         if (l4proto->ctl_compat_table != NULL) {
244                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
245                                             nf_net_ipv4_netfilter_sysctl_path,
246                                             l4proto->ctl_compat_table, NULL);
247                 if (err == 0)
248                         goto out;
249                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
250                                         l4proto->ctl_table,
251                                         l4proto->ctl_table_users);
252         }
253 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
254 out:
255 #endif /* CONFIG_SYSCTL */
256         return err;
257 }
258
259 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
260 {
261 #ifdef CONFIG_SYSCTL
262         if (l4proto->ctl_table_header != NULL &&
263             *l4proto->ctl_table_header != NULL)
264                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
265                                         l4proto->ctl_table,
266                                         l4proto->ctl_table_users);
267 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
268         if (l4proto->ctl_compat_table_header != NULL)
269                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
270                                         l4proto->ctl_compat_table, NULL);
271 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
272 #endif /* CONFIG_SYSCTL */
273 }
274
275 /* FIXME: Allow NULL functions and sub in pointers to generic for
276    them. --RR */
277 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
278 {
279         int ret = 0;
280
281         if (l4proto->l3proto >= PF_MAX)
282                 return -EBUSY;
283
284         mutex_lock(&nf_ct_proto_mutex);
285         if (!nf_ct_protos[l4proto->l3proto]) {
286                 /* l3proto may be loaded latter. */
287                 struct nf_conntrack_l4proto **proto_array;
288                 int i;
289
290                 proto_array = kmalloc(MAX_NF_CT_PROTO *
291                                       sizeof(struct nf_conntrack_l4proto *),
292                                       GFP_KERNEL);
293                 if (proto_array == NULL) {
294                         ret = -ENOMEM;
295                         goto out_unlock;
296                 }
297
298                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
299                         proto_array[i] = &nf_conntrack_l4proto_generic;
300                 nf_ct_protos[l4proto->l3proto] = proto_array;
301         } else if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto] !=
302                                         &nf_conntrack_l4proto_generic) {
303                 ret = -EBUSY;
304                 goto out_unlock;
305         }
306
307         ret = nf_ct_l4proto_register_sysctl(l4proto);
308         if (ret < 0)
309                 goto out_unlock;
310
311         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
312                            l4proto);
313
314 out_unlock:
315         mutex_unlock(&nf_ct_proto_mutex);
316         return ret;
317 }
318 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
319
320 void nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
321 {
322         BUG_ON(l4proto->l3proto >= PF_MAX);
323
324         mutex_lock(&nf_ct_proto_mutex);
325         BUG_ON(nf_ct_protos[l4proto->l3proto][l4proto->l4proto] != l4proto);
326         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
327                            &nf_conntrack_l4proto_generic);
328         nf_ct_l4proto_unregister_sysctl(l4proto);
329         mutex_unlock(&nf_ct_proto_mutex);
330
331         synchronize_rcu();
332
333         /* Remove all contrack entries for this protocol */
334         nf_ct_iterate_cleanup(kill_l4proto, l4proto);
335 }
336 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);
337
338 int nf_conntrack_proto_init(void)
339 {
340         unsigned int i;
341         int err;
342
343         err = nf_ct_l4proto_register_sysctl(&nf_conntrack_l4proto_generic);
344         if (err < 0)
345                 return err;
346
347         for (i = 0; i < AF_MAX; i++)
348                 rcu_assign_pointer(nf_ct_l3protos[i],
349                                    &nf_conntrack_l3proto_generic);
350         return 0;
351 }
352
353 void nf_conntrack_proto_fini(void)
354 {
355         unsigned int i;
356
357         nf_ct_l4proto_unregister_sysctl(&nf_conntrack_l4proto_generic);
358
359         /* free l3proto protocol tables */
360         for (i = 0; i < PF_MAX; i++)
361                 kfree(nf_ct_protos[i]);
362 }