[NETFILTER]: nf_conntrack: move conntrack protocol sysctls to individual modules
[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
34 #ifdef CONFIG_SYSCTL
35 static DEFINE_MUTEX(nf_ct_proto_sysctl_mutex);
36
37 static int
38 nf_ct_register_sysctl(struct ctl_table_header **header, struct ctl_table *path,
39                       struct ctl_table *table, unsigned int *users)
40 {
41         if (*header == NULL) {
42                 *header = nf_register_sysctl_table(path, table);
43                 if (*header == NULL)
44                         return -ENOMEM;
45         }
46         if (users != NULL)
47                 (*users)++;
48         return 0;
49 }
50
51 static void
52 nf_ct_unregister_sysctl(struct ctl_table_header **header,
53                         struct ctl_table *table, unsigned int *users)
54 {
55         if (users != NULL && --*users > 0)
56                 return;
57         nf_unregister_sysctl_table(*header, table);
58         *header = NULL;
59 }
60 #endif
61
62 struct nf_conntrack_l4proto *
63 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
64 {
65         if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
66                 return &nf_conntrack_l4proto_generic;
67
68         return nf_ct_protos[l3proto][l4proto];
69 }
70
71 /* this is guaranteed to always return a valid protocol helper, since
72  * it falls back to generic_protocol */
73 struct nf_conntrack_l4proto *
74 nf_ct_l4proto_find_get(u_int16_t l3proto, u_int8_t l4proto)
75 {
76         struct nf_conntrack_l4proto *p;
77
78         preempt_disable();
79         p = __nf_ct_l4proto_find(l3proto, l4proto);
80         if (!try_module_get(p->me))
81                 p = &nf_conntrack_l4proto_generic;
82         preempt_enable();
83
84         return p;
85 }
86
87 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
88 {
89         module_put(p->me);
90 }
91
92 struct nf_conntrack_l3proto *
93 nf_ct_l3proto_find_get(u_int16_t l3proto)
94 {
95         struct nf_conntrack_l3proto *p;
96
97         preempt_disable();
98         p = __nf_ct_l3proto_find(l3proto);
99         if (!try_module_get(p->me))
100                 p = &nf_conntrack_l3proto_generic;
101         preempt_enable();
102
103         return p;
104 }
105
106 void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
107 {
108         module_put(p->me);
109 }
110
111 int
112 nf_ct_l3proto_try_module_get(unsigned short l3proto)
113 {
114         int ret;
115         struct nf_conntrack_l3proto *p;
116
117 retry:  p = nf_ct_l3proto_find_get(l3proto);
118         if (p == &nf_conntrack_l3proto_generic) {
119                 ret = request_module("nf_conntrack-%d", l3proto);
120                 if (!ret)
121                         goto retry;
122
123                 return -EPROTOTYPE;
124         }
125
126         return 0;
127 }
128
129 void nf_ct_l3proto_module_put(unsigned short l3proto)
130 {
131         struct nf_conntrack_l3proto *p;
132
133         preempt_disable();
134         p = __nf_ct_l3proto_find(l3proto);
135         preempt_enable();
136
137         module_put(p->me);
138 }
139
140 static int kill_l3proto(struct nf_conn *i, void *data)
141 {
142         return (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num ==
143                         ((struct nf_conntrack_l3proto *)data)->l3proto);
144 }
145
146 static int kill_l4proto(struct nf_conn *i, void *data)
147 {
148         struct nf_conntrack_l4proto *l4proto;
149         l4proto = (struct nf_conntrack_l4proto *)data;
150         return (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum ==
151                         l4proto->l4proto) &&
152                (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num ==
153                         l4proto->l3proto);
154 }
155
156 static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
157 {
158         int err = 0;
159
160 #ifdef CONFIG_SYSCTL
161         mutex_lock(&nf_ct_proto_sysctl_mutex);
162         if (l3proto->ctl_table != NULL) {
163                 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
164                                             l3proto->ctl_table_path,
165                                             l3proto->ctl_table, NULL);
166         }
167         mutex_unlock(&nf_ct_proto_sysctl_mutex);
168 #endif
169         return err;
170 }
171
172 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
173 {
174 #ifdef CONFIG_SYSCTL
175         mutex_lock(&nf_ct_proto_sysctl_mutex);
176         if (l3proto->ctl_table_header != NULL)
177                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
178                                         l3proto->ctl_table, NULL);
179         mutex_unlock(&nf_ct_proto_sysctl_mutex);
180 #endif
181 }
182
183 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
184 {
185         int ret = 0;
186
187         if (proto->l3proto >= AF_MAX) {
188                 ret = -EBUSY;
189                 goto out;
190         }
191
192         write_lock_bh(&nf_conntrack_lock);
193         if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
194                 ret = -EBUSY;
195                 goto out_unlock;
196         }
197         nf_ct_l3protos[proto->l3proto] = proto;
198         write_unlock_bh(&nf_conntrack_lock);
199
200         ret = nf_ct_l3proto_register_sysctl(proto);
201         if (ret < 0)
202                 nf_conntrack_l3proto_unregister(proto);
203         return ret;
204
205 out_unlock:
206         write_unlock_bh(&nf_conntrack_lock);
207 out:
208         return ret;
209 }
210
211 int nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
212 {
213         int ret = 0;
214
215         if (proto->l3proto >= AF_MAX) {
216                 ret = -EBUSY;
217                 goto out;
218         }
219
220         write_lock_bh(&nf_conntrack_lock);
221         if (nf_ct_l3protos[proto->l3proto] != proto) {
222                 write_unlock_bh(&nf_conntrack_lock);
223                 ret = -EBUSY;
224                 goto out;
225         }
226
227         nf_ct_l3protos[proto->l3proto] = &nf_conntrack_l3proto_generic;
228         write_unlock_bh(&nf_conntrack_lock);
229
230         nf_ct_l3proto_unregister_sysctl(proto);
231
232         /* Somebody could be still looking at the proto in bh. */
233         synchronize_net();
234
235         /* Remove all contrack entries for this protocol */
236         nf_ct_iterate_cleanup(kill_l3proto, proto);
237
238 out:
239         return ret;
240 }
241
242 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
243 {
244         int err = 0;
245
246 #ifdef CONFIG_SYSCTL
247         mutex_lock(&nf_ct_proto_sysctl_mutex);
248         if (l4proto->ctl_table != NULL) {
249                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
250                                             nf_net_netfilter_sysctl_path,
251                                             l4proto->ctl_table,
252                                             l4proto->ctl_table_users);
253         }
254         mutex_unlock(&nf_ct_proto_sysctl_mutex);
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         mutex_lock(&nf_ct_proto_sysctl_mutex);
263         if (l4proto->ctl_table_header != NULL &&
264             *l4proto->ctl_table_header != NULL)
265                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
266                                         l4proto->ctl_table,
267                                         l4proto->ctl_table_users);
268         mutex_unlock(&nf_ct_proto_sysctl_mutex);
269 #endif /* CONFIG_SYSCTL */
270 }
271
272 /* FIXME: Allow NULL functions and sub in pointers to generic for
273    them. --RR */
274 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
275 {
276         int ret = 0;
277
278         if (l4proto->l3proto >= PF_MAX) {
279                 ret = -EBUSY;
280                 goto out;
281         }
282
283         if (l4proto == &nf_conntrack_l4proto_generic)
284                 return nf_ct_l4proto_register_sysctl(l4proto);
285
286 retry:
287         write_lock_bh(&nf_conntrack_lock);
288         if (nf_ct_protos[l4proto->l3proto]) {
289                 if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
290                                 != &nf_conntrack_l4proto_generic) {
291                         ret = -EBUSY;
292                         goto out_unlock;
293                 }
294         } else {
295                 /* l3proto may be loaded latter. */
296                 struct nf_conntrack_l4proto **proto_array;
297                 int i;
298
299                 write_unlock_bh(&nf_conntrack_lock);
300
301                 proto_array = (struct nf_conntrack_l4proto **)
302                                 kmalloc(MAX_NF_CT_PROTO *
303                                          sizeof(struct nf_conntrack_l4proto *),
304                                         GFP_KERNEL);
305                 if (proto_array == NULL) {
306                         ret = -ENOMEM;
307                         goto out;
308                 }
309                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
310                         proto_array[i] = &nf_conntrack_l4proto_generic;
311
312                 write_lock_bh(&nf_conntrack_lock);
313                 if (nf_ct_protos[l4proto->l3proto]) {
314                         /* bad timing, but no problem */
315                         write_unlock_bh(&nf_conntrack_lock);
316                         kfree(proto_array);
317                 } else {
318                         nf_ct_protos[l4proto->l3proto] = proto_array;
319                         write_unlock_bh(&nf_conntrack_lock);
320                 }
321
322                 /*
323                  * Just once because array is never freed until unloading
324                  * nf_conntrack.ko
325                  */
326                 goto retry;
327         }
328
329         nf_ct_protos[l4proto->l3proto][l4proto->l4proto] = l4proto;
330         write_unlock_bh(&nf_conntrack_lock);
331
332         ret = nf_ct_l4proto_register_sysctl(l4proto);
333         if (ret < 0)
334                 nf_conntrack_l4proto_unregister(l4proto);
335         return ret;
336
337 out_unlock:
338         write_unlock_bh(&nf_conntrack_lock);
339 out:
340         return ret;
341 }
342
343 int nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
344 {
345         int ret = 0;
346
347         if (l4proto->l3proto >= PF_MAX) {
348                 ret = -EBUSY;
349                 goto out;
350         }
351
352         if (l4proto == &nf_conntrack_l4proto_generic) {
353                 nf_ct_l4proto_unregister_sysctl(l4proto);
354                 goto out;
355         }
356
357         write_lock_bh(&nf_conntrack_lock);
358         if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
359             != l4proto) {
360                 write_unlock_bh(&nf_conntrack_lock);
361                 ret = -EBUSY;
362                 goto out;
363         }
364         nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
365                 = &nf_conntrack_l4proto_generic;
366         write_unlock_bh(&nf_conntrack_lock);
367
368         nf_ct_l4proto_unregister_sysctl(l4proto);
369
370         /* Somebody could be still looking at the proto in bh. */
371         synchronize_net();
372
373         /* Remove all contrack entries for this protocol */
374         nf_ct_iterate_cleanup(kill_l4proto, l4proto);
375
376 out:
377         return ret;
378 }