5701c8dd783c02df1ef6d055f473845754e37d30
[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/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
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_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
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
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
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 static int kill_l3proto(struct nf_conn *i, void *data)
131 {
132         return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
133 }
134
135 static int kill_l4proto(struct nf_conn *i, void *data)
136 {
137         struct nf_conntrack_l4proto *l4proto;
138         l4proto = (struct nf_conntrack_l4proto *)data;
139         return nf_ct_protonum(i) == l4proto->l4proto &&
140                nf_ct_l3num(i) == l4proto->l3proto;
141 }
142
143 static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
144 {
145         int err = 0;
146
147 #ifdef CONFIG_SYSCTL
148         if (l3proto->ctl_table != NULL) {
149                 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
150                                             l3proto->ctl_table_path,
151                                             l3proto->ctl_table, NULL);
152         }
153 #endif
154         return err;
155 }
156
157 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
158 {
159 #ifdef CONFIG_SYSCTL
160         if (l3proto->ctl_table_header != NULL)
161                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
162                                         l3proto->ctl_table, NULL);
163 #endif
164 }
165
166 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
167 {
168         int ret = 0;
169         struct nf_conntrack_l3proto *old;
170
171         if (proto->l3proto >= AF_MAX)
172                 return -EBUSY;
173
174         if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
175                 return -EINVAL;
176
177         mutex_lock(&nf_ct_proto_mutex);
178         old = rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
179                                         lockdep_is_held(&nf_ct_proto_mutex));
180         if (old != &nf_conntrack_l3proto_generic) {
181                 ret = -EBUSY;
182                 goto out_unlock;
183         }
184
185         ret = nf_ct_l3proto_register_sysctl(proto);
186         if (ret < 0)
187                 goto out_unlock;
188
189         if (proto->nlattr_tuple_size)
190                 proto->nla_size = 3 * proto->nlattr_tuple_size();
191
192         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
193
194 out_unlock:
195         mutex_unlock(&nf_ct_proto_mutex);
196         return ret;
197 }
198 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
199
200 void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
201 {
202         struct net *net;
203
204         BUG_ON(proto->l3proto >= AF_MAX);
205
206         mutex_lock(&nf_ct_proto_mutex);
207         BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
208                                          lockdep_is_held(&nf_ct_proto_mutex)
209                                          ) != proto);
210         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
211                            &nf_conntrack_l3proto_generic);
212         nf_ct_l3proto_unregister_sysctl(proto);
213         mutex_unlock(&nf_ct_proto_mutex);
214
215         synchronize_rcu();
216
217         /* Remove all contrack entries for this protocol */
218         rtnl_lock();
219         for_each_net(net)
220                 nf_ct_iterate_cleanup(net, kill_l3proto, proto);
221         rtnl_unlock();
222 }
223 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
224
225 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
226 {
227         int err = 0;
228
229 #ifdef CONFIG_SYSCTL
230         if (l4proto->ctl_table != NULL) {
231                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
232                                             nf_net_netfilter_sysctl_path,
233                                             l4proto->ctl_table,
234                                             l4proto->ctl_table_users);
235                 if (err < 0)
236                         goto out;
237         }
238 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
239         if (l4proto->ctl_compat_table != NULL) {
240                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
241                                             nf_net_ipv4_netfilter_sysctl_path,
242                                             l4proto->ctl_compat_table, NULL);
243                 if (err == 0)
244                         goto out;
245                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
246                                         l4proto->ctl_table,
247                                         l4proto->ctl_table_users);
248         }
249 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
250 out:
251 #endif /* CONFIG_SYSCTL */
252         return err;
253 }
254
255 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
256 {
257 #ifdef CONFIG_SYSCTL
258         if (l4proto->ctl_table_header != NULL &&
259             *l4proto->ctl_table_header != NULL)
260                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
261                                         l4proto->ctl_table,
262                                         l4proto->ctl_table_users);
263 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
264         if (l4proto->ctl_compat_table_header != NULL)
265                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
266                                         l4proto->ctl_compat_table, NULL);
267 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
268 #endif /* CONFIG_SYSCTL */
269 }
270
271 /* FIXME: Allow NULL functions and sub in pointers to generic for
272    them. --RR */
273 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
274 {
275         int ret = 0;
276
277         if (l4proto->l3proto >= PF_MAX)
278                 return -EBUSY;
279
280         if ((l4proto->to_nlattr && !l4proto->nlattr_size)
281                 || (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
282                 return -EINVAL;
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 __rcu **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                         RCU_INIT_POINTER(proto_array[i], &nf_conntrack_l4proto_generic);
300
301                 /* Before making proto_array visible to lockless readers,
302                  * we must make sure its content is committed to memory.
303                  */
304                 smp_wmb();
305
306                 nf_ct_protos[l4proto->l3proto] = proto_array;
307         } else if (rcu_dereference_protected(
308                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
309                         lockdep_is_held(&nf_ct_proto_mutex)
310                         ) != &nf_conntrack_l4proto_generic) {
311                 ret = -EBUSY;
312                 goto out_unlock;
313         }
314
315         ret = nf_ct_l4proto_register_sysctl(l4proto);
316         if (ret < 0)
317                 goto out_unlock;
318
319         l4proto->nla_size = 0;
320         if (l4proto->nlattr_size)
321                 l4proto->nla_size += l4proto->nlattr_size();
322         if (l4proto->nlattr_tuple_size)
323                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
324
325         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
326                            l4proto);
327
328 out_unlock:
329         mutex_unlock(&nf_ct_proto_mutex);
330         return ret;
331 }
332 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
333
334 void nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
335 {
336         struct net *net;
337
338         BUG_ON(l4proto->l3proto >= PF_MAX);
339
340         mutex_lock(&nf_ct_proto_mutex);
341         BUG_ON(rcu_dereference_protected(
342                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
343                         lockdep_is_held(&nf_ct_proto_mutex)
344                         ) != l4proto);
345         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
346                            &nf_conntrack_l4proto_generic);
347         nf_ct_l4proto_unregister_sysctl(l4proto);
348         mutex_unlock(&nf_ct_proto_mutex);
349
350         synchronize_rcu();
351
352         /* Remove all contrack entries for this protocol */
353         rtnl_lock();
354         for_each_net(net)
355                 nf_ct_iterate_cleanup(net, kill_l4proto, l4proto);
356         rtnl_unlock();
357 }
358 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);
359
360 int nf_conntrack_proto_init(void)
361 {
362         unsigned int i;
363         int err;
364
365         err = nf_ct_l4proto_register_sysctl(&nf_conntrack_l4proto_generic);
366         if (err < 0)
367                 return err;
368
369         for (i = 0; i < AF_MAX; i++)
370                 rcu_assign_pointer(nf_ct_l3protos[i],
371                                    &nf_conntrack_l3proto_generic);
372         return 0;
373 }
374
375 void nf_conntrack_proto_fini(void)
376 {
377         unsigned int i;
378
379         nf_ct_l4proto_unregister_sysctl(&nf_conntrack_l4proto_generic);
380
381         /* free l3proto protocol tables */
382         for (i = 0; i < PF_MAX; i++)
383                 kfree(nf_ct_protos[i]);
384 }