[NETFILTER]: nf_conntrack: properly use RCU API for nf_ct_protos/nf_ct_l3protos arrays
[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 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 #ifdef CONFIG_SYSCTL
36 static DEFINE_MUTEX(nf_ct_proto_sysctl_mutex);
37
38 static int
39 nf_ct_register_sysctl(struct ctl_table_header **header, struct ctl_table *path,
40                       struct ctl_table *table, unsigned int *users)
41 {
42         if (*header == NULL) {
43                 *header = nf_register_sysctl_table(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         nf_unregister_sysctl_table(*header, table);
59         *header = NULL;
60 }
61 #endif
62
63 struct nf_conntrack_l4proto *
64 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
65 {
66         if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
67                 return &nf_conntrack_l4proto_generic;
68
69         return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
70 }
71 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
72
73 /* this is guaranteed to always return a valid protocol helper, since
74  * it falls back to generic_protocol */
75 struct nf_conntrack_l4proto *
76 nf_ct_l4proto_find_get(u_int16_t l3proto, u_int8_t l4proto)
77 {
78         struct nf_conntrack_l4proto *p;
79
80         rcu_read_lock();
81         p = __nf_ct_l4proto_find(l3proto, l4proto);
82         if (!try_module_get(p->me))
83                 p = &nf_conntrack_l4proto_generic;
84         rcu_read_unlock();
85
86         return p;
87 }
88 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
89
90 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
91 {
92         module_put(p->me);
93 }
94 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
95
96 struct nf_conntrack_l3proto *
97 nf_ct_l3proto_find_get(u_int16_t l3proto)
98 {
99         struct nf_conntrack_l3proto *p;
100
101         rcu_read_lock();
102         p = __nf_ct_l3proto_find(l3proto);
103         if (!try_module_get(p->me))
104                 p = &nf_conntrack_l3proto_generic;
105         rcu_read_unlock();
106
107         return p;
108 }
109 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
110
111 void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
112 {
113         module_put(p->me);
114 }
115 EXPORT_SYMBOL_GPL(nf_ct_l3proto_put);
116
117 int
118 nf_ct_l3proto_try_module_get(unsigned short l3proto)
119 {
120         int ret;
121         struct nf_conntrack_l3proto *p;
122
123 retry:  p = nf_ct_l3proto_find_get(l3proto);
124         if (p == &nf_conntrack_l3proto_generic) {
125                 ret = request_module("nf_conntrack-%d", l3proto);
126                 if (!ret)
127                         goto retry;
128
129                 return -EPROTOTYPE;
130         }
131
132         return 0;
133 }
134 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
135
136 void nf_ct_l3proto_module_put(unsigned short l3proto)
137 {
138         struct nf_conntrack_l3proto *p;
139
140         /* rcu_read_lock not necessary since the caller holds a reference */
141         p = __nf_ct_l3proto_find(l3proto);
142         module_put(p->me);
143 }
144 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
145
146 static int kill_l3proto(struct nf_conn *i, void *data)
147 {
148         return (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num ==
149                         ((struct nf_conntrack_l3proto *)data)->l3proto);
150 }
151
152 static int kill_l4proto(struct nf_conn *i, void *data)
153 {
154         struct nf_conntrack_l4proto *l4proto;
155         l4proto = (struct nf_conntrack_l4proto *)data;
156         return (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum ==
157                         l4proto->l4proto) &&
158                (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num ==
159                         l4proto->l3proto);
160 }
161
162 static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
163 {
164         int err = 0;
165
166 #ifdef CONFIG_SYSCTL
167         mutex_lock(&nf_ct_proto_sysctl_mutex);
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         mutex_unlock(&nf_ct_proto_sysctl_mutex);
174 #endif
175         return err;
176 }
177
178 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
179 {
180 #ifdef CONFIG_SYSCTL
181         mutex_lock(&nf_ct_proto_sysctl_mutex);
182         if (l3proto->ctl_table_header != NULL)
183                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
184                                         l3proto->ctl_table, NULL);
185         mutex_unlock(&nf_ct_proto_sysctl_mutex);
186 #endif
187 }
188
189 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
190 {
191         int ret = 0;
192
193         if (proto->l3proto >= AF_MAX) {
194                 ret = -EBUSY;
195                 goto out;
196         }
197
198         write_lock_bh(&nf_conntrack_lock);
199         if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
200                 ret = -EBUSY;
201                 goto out_unlock;
202         }
203         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
204         write_unlock_bh(&nf_conntrack_lock);
205
206         ret = nf_ct_l3proto_register_sysctl(proto);
207         if (ret < 0)
208                 nf_conntrack_l3proto_unregister(proto);
209         return ret;
210
211 out_unlock:
212         write_unlock_bh(&nf_conntrack_lock);
213 out:
214         return ret;
215 }
216 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
217
218 int nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
219 {
220         int ret = 0;
221
222         if (proto->l3proto >= AF_MAX) {
223                 ret = -EBUSY;
224                 goto out;
225         }
226
227         write_lock_bh(&nf_conntrack_lock);
228         if (nf_ct_l3protos[proto->l3proto] != proto) {
229                 write_unlock_bh(&nf_conntrack_lock);
230                 ret = -EBUSY;
231                 goto out;
232         }
233
234         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
235                            &nf_conntrack_l3proto_generic);
236         write_unlock_bh(&nf_conntrack_lock);
237         synchronize_rcu();
238
239         nf_ct_l3proto_unregister_sysctl(proto);
240
241         /* Remove all contrack entries for this protocol */
242         nf_ct_iterate_cleanup(kill_l3proto, proto);
243
244 out:
245         return ret;
246 }
247 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
248
249 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
250 {
251         int err = 0;
252
253 #ifdef CONFIG_SYSCTL
254         mutex_lock(&nf_ct_proto_sysctl_mutex);
255         if (l4proto->ctl_table != NULL) {
256                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
257                                             nf_net_netfilter_sysctl_path,
258                                             l4proto->ctl_table,
259                                             l4proto->ctl_table_users);
260                 if (err < 0)
261                         goto out;
262         }
263 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
264         if (l4proto->ctl_compat_table != NULL) {
265                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
266                                             nf_net_ipv4_netfilter_sysctl_path,
267                                             l4proto->ctl_compat_table, NULL);
268                 if (err == 0)
269                         goto out;
270                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
271                                         l4proto->ctl_table,
272                                         l4proto->ctl_table_users);
273         }
274 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
275 out:
276         mutex_unlock(&nf_ct_proto_sysctl_mutex);
277 #endif /* CONFIG_SYSCTL */
278         return err;
279 }
280
281 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
282 {
283 #ifdef CONFIG_SYSCTL
284         mutex_lock(&nf_ct_proto_sysctl_mutex);
285         if (l4proto->ctl_table_header != NULL &&
286             *l4proto->ctl_table_header != NULL)
287                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
288                                         l4proto->ctl_table,
289                                         l4proto->ctl_table_users);
290 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
291         if (l4proto->ctl_compat_table_header != NULL)
292                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
293                                         l4proto->ctl_compat_table, NULL);
294 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
295         mutex_unlock(&nf_ct_proto_sysctl_mutex);
296 #endif /* CONFIG_SYSCTL */
297 }
298
299 /* FIXME: Allow NULL functions and sub in pointers to generic for
300    them. --RR */
301 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
302 {
303         int ret = 0;
304
305         if (l4proto->l3proto >= PF_MAX) {
306                 ret = -EBUSY;
307                 goto out;
308         }
309
310         if (l4proto == &nf_conntrack_l4proto_generic)
311                 return nf_ct_l4proto_register_sysctl(l4proto);
312
313 retry:
314         write_lock_bh(&nf_conntrack_lock);
315         if (nf_ct_protos[l4proto->l3proto]) {
316                 if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
317                                 != &nf_conntrack_l4proto_generic) {
318                         ret = -EBUSY;
319                         goto out_unlock;
320                 }
321         } else {
322                 /* l3proto may be loaded latter. */
323                 struct nf_conntrack_l4proto **proto_array;
324                 int i;
325
326                 write_unlock_bh(&nf_conntrack_lock);
327
328                 proto_array = (struct nf_conntrack_l4proto **)
329                                 kmalloc(MAX_NF_CT_PROTO *
330                                          sizeof(struct nf_conntrack_l4proto *),
331                                         GFP_KERNEL);
332                 if (proto_array == NULL) {
333                         ret = -ENOMEM;
334                         goto out;
335                 }
336                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
337                         proto_array[i] = &nf_conntrack_l4proto_generic;
338
339                 write_lock_bh(&nf_conntrack_lock);
340                 if (nf_ct_protos[l4proto->l3proto]) {
341                         /* bad timing, but no problem */
342                         write_unlock_bh(&nf_conntrack_lock);
343                         kfree(proto_array);
344                 } else {
345                         nf_ct_protos[l4proto->l3proto] = proto_array;
346                         write_unlock_bh(&nf_conntrack_lock);
347                 }
348
349                 /*
350                  * Just once because array is never freed until unloading
351                  * nf_conntrack.ko
352                  */
353                 goto retry;
354         }
355
356         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto], l4proto);
357         write_unlock_bh(&nf_conntrack_lock);
358
359         ret = nf_ct_l4proto_register_sysctl(l4proto);
360         if (ret < 0)
361                 nf_conntrack_l4proto_unregister(l4proto);
362         return ret;
363
364 out_unlock:
365         write_unlock_bh(&nf_conntrack_lock);
366 out:
367         return ret;
368 }
369 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
370
371 int nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
372 {
373         int ret = 0;
374
375         if (l4proto->l3proto >= PF_MAX) {
376                 ret = -EBUSY;
377                 goto out;
378         }
379
380         if (l4proto == &nf_conntrack_l4proto_generic) {
381                 nf_ct_l4proto_unregister_sysctl(l4proto);
382                 goto out;
383         }
384
385         write_lock_bh(&nf_conntrack_lock);
386         if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
387             != l4proto) {
388                 write_unlock_bh(&nf_conntrack_lock);
389                 ret = -EBUSY;
390                 goto out;
391         }
392         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
393                            &nf_conntrack_l4proto_generic);
394         write_unlock_bh(&nf_conntrack_lock);
395         synchronize_rcu();
396
397         nf_ct_l4proto_unregister_sysctl(l4proto);
398
399         /* Remove all contrack entries for this protocol */
400         nf_ct_iterate_cleanup(kill_l4proto, l4proto);
401
402 out:
403         return ret;
404 }
405 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);