[NETFILTER]: nf_conntrack: simplify protocol locking
[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 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_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         if (l3proto->ctl_table != NULL) {
168                 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
169                                             l3proto->ctl_table_path,
170                                             l3proto->ctl_table, NULL);
171         }
172 #endif
173         return err;
174 }
175
176 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
177 {
178 #ifdef CONFIG_SYSCTL
179         if (l3proto->ctl_table_header != NULL)
180                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
181                                         l3proto->ctl_table, NULL);
182 #endif
183 }
184
185 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
186 {
187         int ret = 0;
188
189         if (proto->l3proto >= AF_MAX)
190                 return -EBUSY;
191
192         mutex_lock(&nf_ct_proto_mutex);
193         if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
194                 ret = -EBUSY;
195                 goto out_unlock;
196         }
197
198         ret = nf_ct_l3proto_register_sysctl(proto);
199         if (ret < 0)
200                 goto out_unlock;
201
202         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
203
204 out_unlock:
205         mutex_unlock(&nf_ct_proto_mutex);
206         return ret;
207 }
208 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
209
210 void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
211 {
212         BUG_ON(proto->l3proto >= AF_MAX);
213
214         mutex_lock(&nf_ct_proto_mutex);
215         BUG_ON(nf_ct_l3protos[proto->l3proto] != proto);
216         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
217                            &nf_conntrack_l3proto_generic);
218         nf_ct_l3proto_unregister_sysctl(proto);
219         mutex_unlock(&nf_ct_proto_mutex);
220
221         synchronize_rcu();
222
223         /* Remove all contrack entries for this protocol */
224         nf_ct_iterate_cleanup(kill_l3proto, proto);
225 }
226 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
227
228 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
229 {
230         int err = 0;
231
232 #ifdef CONFIG_SYSCTL
233         if (l4proto->ctl_table != NULL) {
234                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
235                                             nf_net_netfilter_sysctl_path,
236                                             l4proto->ctl_table,
237                                             l4proto->ctl_table_users);
238                 if (err < 0)
239                         goto out;
240         }
241 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
242         if (l4proto->ctl_compat_table != NULL) {
243                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
244                                             nf_net_ipv4_netfilter_sysctl_path,
245                                             l4proto->ctl_compat_table, NULL);
246                 if (err == 0)
247                         goto out;
248                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
249                                         l4proto->ctl_table,
250                                         l4proto->ctl_table_users);
251         }
252 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
253 out:
254 #endif /* CONFIG_SYSCTL */
255         return err;
256 }
257
258 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
259 {
260 #ifdef CONFIG_SYSCTL
261         if (l4proto->ctl_table_header != NULL &&
262             *l4proto->ctl_table_header != NULL)
263                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
264                                         l4proto->ctl_table,
265                                         l4proto->ctl_table_users);
266 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
267         if (l4proto->ctl_compat_table_header != NULL)
268                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
269                                         l4proto->ctl_compat_table, NULL);
270 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
271 #endif /* CONFIG_SYSCTL */
272 }
273
274 /* FIXME: Allow NULL functions and sub in pointers to generic for
275    them. --RR */
276 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
277 {
278         int ret = 0;
279
280         if (l4proto->l3proto >= PF_MAX)
281                 return -EBUSY;
282
283         mutex_lock(&nf_ct_proto_mutex);
284 retry:
285         if (nf_ct_protos[l4proto->l3proto]) {
286                 if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
287                                 != &nf_conntrack_l4proto_generic) {
288                         ret = -EBUSY;
289                         goto out_unlock;
290                 }
291         } else {
292                 /* l3proto may be loaded latter. */
293                 struct nf_conntrack_l4proto **proto_array;
294                 int i;
295
296                 proto_array = (struct nf_conntrack_l4proto **)
297                                 kmalloc(MAX_NF_CT_PROTO *
298                                          sizeof(struct nf_conntrack_l4proto *),
299                                         GFP_KERNEL);
300                 if (proto_array == NULL) {
301                         ret = -ENOMEM;
302                         goto out_unlock;
303                 }
304                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
305                         proto_array[i] = &nf_conntrack_l4proto_generic;
306
307                 if (nf_ct_protos[l4proto->l3proto])
308                         /* bad timing, but no problem */
309                         kfree(proto_array);
310                 else
311                         nf_ct_protos[l4proto->l3proto] = proto_array;
312
313                 /*
314                  * Just once because array is never freed until unloading
315                  * nf_conntrack.ko
316                  */
317                 goto retry;
318         }
319
320         ret = nf_ct_l4proto_register_sysctl(l4proto);
321         if (ret < 0)
322                 goto out_unlock;
323
324         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto], l4proto);
325
326 out_unlock:
327         mutex_unlock(&nf_ct_proto_mutex);
328         return ret;
329 }
330 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
331
332 void nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
333 {
334         BUG_ON(l4proto->l3proto >= PF_MAX);
335
336         mutex_lock(&nf_ct_proto_mutex);
337         BUG_ON(nf_ct_protos[l4proto->l3proto][l4proto->l4proto] != l4proto);
338         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
339                            &nf_conntrack_l4proto_generic);
340         nf_ct_l4proto_unregister_sysctl(l4proto);
341         mutex_unlock(&nf_ct_proto_mutex);
342
343         synchronize_rcu();
344
345         /* Remove all contrack entries for this protocol */
346         nf_ct_iterate_cleanup(kill_l4proto, l4proto);
347 }
348 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);
349
350 int nf_conntrack_proto_init(void)
351 {
352         unsigned int i;
353         int err;
354
355         err = nf_ct_l4proto_register_sysctl(&nf_conntrack_l4proto_generic);
356         if (err < 0)
357                 return err;
358
359         for (i = 0; i < AF_MAX; i++)
360                 rcu_assign_pointer(nf_ct_l3protos[i],
361                                    &nf_conntrack_l3proto_generic);
362         return 0;
363 }
364
365 void nf_conntrack_proto_fini(void)
366 {
367         unsigned int i;
368
369         nf_ct_l4proto_unregister_sysctl(&nf_conntrack_l4proto_generic);
370
371         /* free l3proto protocol tables */
372         for (i = 0; i < PF_MAX; i++)
373                 kfree(nf_ct_protos[i]);
374 }