[NETLINK]: Mark netlink policies const
[linux-2.6.git] / net / netlink / genetlink.c
1 /*
2  * NETLINK      Generic Netlink Family
3  *
4  *              Authors:        Jamal Hadi Salim
5  *                              Thomas Graf <tgraf@suug.ch>
6  */
7
8 #include <linux/module.h>
9 #include <linux/kernel.h>
10 #include <linux/errno.h>
11 #include <linux/types.h>
12 #include <linux/socket.h>
13 #include <linux/string.h>
14 #include <linux/skbuff.h>
15 #include <linux/mutex.h>
16 #include <net/sock.h>
17 #include <net/genetlink.h>
18
19 struct sock *genl_sock = NULL;
20
21 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
22
23 static void genl_lock(void)
24 {
25         mutex_lock(&genl_mutex);
26 }
27
28 static int genl_trylock(void)
29 {
30         return !mutex_trylock(&genl_mutex);
31 }
32
33 static void genl_unlock(void)
34 {
35         mutex_unlock(&genl_mutex);
36
37         if (genl_sock && genl_sock->sk_receive_queue.qlen)
38                 genl_sock->sk_data_ready(genl_sock, 0);
39 }
40
41 #define GENL_FAM_TAB_SIZE       16
42 #define GENL_FAM_TAB_MASK       (GENL_FAM_TAB_SIZE - 1)
43
44 static struct list_head family_ht[GENL_FAM_TAB_SIZE];
45
46 static int genl_ctrl_event(int event, void *data);
47
48 static inline unsigned int genl_family_hash(unsigned int id)
49 {
50         return id & GENL_FAM_TAB_MASK;
51 }
52
53 static inline struct list_head *genl_family_chain(unsigned int id)
54 {
55         return &family_ht[genl_family_hash(id)];
56 }
57
58 static struct genl_family *genl_family_find_byid(unsigned int id)
59 {
60         struct genl_family *f;
61
62         list_for_each_entry(f, genl_family_chain(id), family_list)
63                 if (f->id == id)
64                         return f;
65
66         return NULL;
67 }
68
69 static struct genl_family *genl_family_find_byname(char *name)
70 {
71         struct genl_family *f;
72         int i;
73
74         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
75                 list_for_each_entry(f, genl_family_chain(i), family_list)
76                         if (strcmp(f->name, name) == 0)
77                                 return f;
78
79         return NULL;
80 }
81
82 static struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
83 {
84         struct genl_ops *ops;
85
86         list_for_each_entry(ops, &family->ops_list, ops_list)
87                 if (ops->cmd == cmd)
88                         return ops;
89
90         return NULL;
91 }
92
93 /* Of course we are going to have problems once we hit
94  * 2^16 alive types, but that can only happen by year 2K
95 */
96 static inline u16 genl_generate_id(void)
97 {
98         static u16 id_gen_idx;
99         int overflowed = 0;
100
101         do {
102                 if (id_gen_idx == 0)
103                         id_gen_idx = GENL_MIN_ID;
104
105                 if (++id_gen_idx > GENL_MAX_ID) {
106                         if (!overflowed) {
107                                 overflowed = 1;
108                                 id_gen_idx = 0;
109                                 continue;
110                         } else
111                                 return 0;
112                 }
113
114         } while (genl_family_find_byid(id_gen_idx));
115
116         return id_gen_idx;
117 }
118
119 /**
120  * genl_register_ops - register generic netlink operations
121  * @family: generic netlink family
122  * @ops: operations to be registered
123  *
124  * Registers the specified operations and assigns them to the specified
125  * family. Either a doit or dumpit callback must be specified or the
126  * operation will fail. Only one operation structure per command
127  * identifier may be registered.
128  *
129  * See include/net/genetlink.h for more documenation on the operations
130  * structure.
131  *
132  * Returns 0 on success or a negative error code.
133  */
134 int genl_register_ops(struct genl_family *family, struct genl_ops *ops)
135 {
136         int err = -EINVAL;
137
138         if (ops->dumpit == NULL && ops->doit == NULL)
139                 goto errout;
140
141         if (genl_get_cmd(ops->cmd, family)) {
142                 err = -EEXIST;
143                 goto errout;
144         }
145
146         if (ops->dumpit)
147                 ops->flags |= GENL_CMD_CAP_DUMP;
148         if (ops->doit)
149                 ops->flags |= GENL_CMD_CAP_DO;
150         if (ops->policy)
151                 ops->flags |= GENL_CMD_CAP_HASPOL;
152
153         genl_lock();
154         list_add_tail(&ops->ops_list, &family->ops_list);
155         genl_unlock();
156
157         genl_ctrl_event(CTRL_CMD_NEWOPS, ops);
158         err = 0;
159 errout:
160         return err;
161 }
162
163 /**
164  * genl_unregister_ops - unregister generic netlink operations
165  * @family: generic netlink family
166  * @ops: operations to be unregistered
167  *
168  * Unregisters the specified operations and unassigns them from the
169  * specified family. The operation blocks until the current message
170  * processing has finished and doesn't start again until the
171  * unregister process has finished.
172  *
173  * Note: It is not necessary to unregister all operations before
174  *       unregistering the family, unregistering the family will cause
175  *       all assigned operations to be unregistered automatically.
176  *
177  * Returns 0 on success or a negative error code.
178  */
179 int genl_unregister_ops(struct genl_family *family, struct genl_ops *ops)
180 {
181         struct genl_ops *rc;
182
183         genl_lock();
184         list_for_each_entry(rc, &family->ops_list, ops_list) {
185                 if (rc == ops) {
186                         list_del(&ops->ops_list);
187                         genl_unlock();
188                         genl_ctrl_event(CTRL_CMD_DELOPS, ops);
189                         return 0;
190                 }
191         }
192         genl_unlock();
193
194         return -ENOENT;
195 }
196
197 /**
198  * genl_register_family - register a generic netlink family
199  * @family: generic netlink family
200  *
201  * Registers the specified family after validating it first. Only one
202  * family may be registered with the same family name or identifier.
203  * The family id may equal GENL_ID_GENERATE causing an unique id to
204  * be automatically generated and assigned.
205  *
206  * Return 0 on success or a negative error code.
207  */
208 int genl_register_family(struct genl_family *family)
209 {
210         int err = -EINVAL;
211
212         if (family->id && family->id < GENL_MIN_ID)
213                 goto errout;
214
215         if (family->id > GENL_MAX_ID)
216                 goto errout;
217
218         INIT_LIST_HEAD(&family->ops_list);
219
220         genl_lock();
221
222         if (genl_family_find_byname(family->name)) {
223                 err = -EEXIST;
224                 goto errout_locked;
225         }
226
227         if (genl_family_find_byid(family->id)) {
228                 err = -EEXIST;
229                 goto errout_locked;
230         }
231
232         if (family->id == GENL_ID_GENERATE) {
233                 u16 newid = genl_generate_id();
234
235                 if (!newid) {
236                         err = -ENOMEM;
237                         goto errout_locked;
238                 }
239
240                 family->id = newid;
241         }
242
243         if (family->maxattr) {
244                 family->attrbuf = kmalloc((family->maxattr+1) *
245                                         sizeof(struct nlattr *), GFP_KERNEL);
246                 if (family->attrbuf == NULL) {
247                         err = -ENOMEM;
248                         goto errout_locked;
249                 }
250         } else
251                 family->attrbuf = NULL;
252
253         list_add_tail(&family->family_list, genl_family_chain(family->id));
254         genl_unlock();
255
256         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);
257
258         return 0;
259
260 errout_locked:
261         genl_unlock();
262 errout:
263         return err;
264 }
265
266 /**
267  * genl_unregister_family - unregister generic netlink family
268  * @family: generic netlink family
269  *
270  * Unregisters the specified family.
271  *
272  * Returns 0 on success or a negative error code.
273  */
274 int genl_unregister_family(struct genl_family *family)
275 {
276         struct genl_family *rc;
277
278         genl_lock();
279
280         list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
281                 if (family->id != rc->id || strcmp(rc->name, family->name))
282                         continue;
283
284                 list_del(&rc->family_list);
285                 INIT_LIST_HEAD(&family->ops_list);
286                 genl_unlock();
287
288                 kfree(family->attrbuf);
289                 genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
290                 return 0;
291         }
292
293         genl_unlock();
294
295         return -ENOENT;
296 }
297
298 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
299 {
300         struct genl_ops *ops;
301         struct genl_family *family;
302         struct genl_info info;
303         struct genlmsghdr *hdr = nlmsg_data(nlh);
304         int hdrlen, err;
305
306         family = genl_family_find_byid(nlh->nlmsg_type);
307         if (family == NULL)
308                 return -ENOENT;
309
310         hdrlen = GENL_HDRLEN + family->hdrsize;
311         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
312                 return -EINVAL;
313
314         ops = genl_get_cmd(hdr->cmd, family);
315         if (ops == NULL)
316                 return -EOPNOTSUPP;
317
318         if ((ops->flags & GENL_ADMIN_PERM) &&
319             security_netlink_recv(skb, CAP_NET_ADMIN))
320                 return -EPERM;
321
322         if (nlh->nlmsg_flags & NLM_F_DUMP) {
323                 if (ops->dumpit == NULL)
324                         return -EOPNOTSUPP;
325
326                 return netlink_dump_start(genl_sock, skb, nlh,
327                                           ops->dumpit, ops->done);
328         }
329
330         if (ops->doit == NULL)
331                 return -EOPNOTSUPP;
332
333         if (family->attrbuf) {
334                 err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr,
335                                   ops->policy);
336                 if (err < 0)
337                         return err;
338         }
339
340         info.snd_seq = nlh->nlmsg_seq;
341         info.snd_pid = NETLINK_CB(skb).pid;
342         info.nlhdr = nlh;
343         info.genlhdr = nlmsg_data(nlh);
344         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
345         info.attrs = family->attrbuf;
346
347         return ops->doit(skb, &info);
348 }
349
350 static void genl_rcv(struct sock *sk, int len)
351 {
352         unsigned int qlen = 0;
353
354         do {
355                 if (genl_trylock())
356                         return;
357                 netlink_run_queue(sk, &qlen, genl_rcv_msg);
358                 genl_unlock();
359         } while (qlen && genl_sock && genl_sock->sk_receive_queue.qlen);
360 }
361
362 /**************************************************************************
363  * Controller
364  **************************************************************************/
365
366 static struct genl_family genl_ctrl = {
367         .id = GENL_ID_CTRL,
368         .name = "nlctrl",
369         .version = 0x2,
370         .maxattr = CTRL_ATTR_MAX,
371 };
372
373 static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
374                           u32 flags, struct sk_buff *skb, u8 cmd)
375 {
376         void *hdr;
377
378         hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
379         if (hdr == NULL)
380                 return -1;
381
382         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, family->name);
383         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, family->id);
384         NLA_PUT_U32(skb, CTRL_ATTR_VERSION, family->version);
385         NLA_PUT_U32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize);
386         NLA_PUT_U32(skb, CTRL_ATTR_MAXATTR, family->maxattr);
387
388         if (!list_empty(&family->ops_list)) {
389                 struct nlattr *nla_ops;
390                 struct genl_ops *ops;
391                 int idx = 1;
392
393                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
394                 if (nla_ops == NULL)
395                         goto nla_put_failure;
396
397                 list_for_each_entry(ops, &family->ops_list, ops_list) {
398                         struct nlattr *nest;
399
400                         nest = nla_nest_start(skb, idx++);
401                         if (nest == NULL)
402                                 goto nla_put_failure;
403
404                         NLA_PUT_U32(skb, CTRL_ATTR_OP_ID, ops->cmd);
405                         NLA_PUT_U32(skb, CTRL_ATTR_OP_FLAGS, ops->flags);
406
407                         nla_nest_end(skb, nest);
408                 }
409
410                 nla_nest_end(skb, nla_ops);
411         }
412
413         return genlmsg_end(skb, hdr);
414
415 nla_put_failure:
416         return genlmsg_cancel(skb, hdr);
417 }
418
419 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
420 {
421
422         int i, n = 0;
423         struct genl_family *rt;
424         int chains_to_skip = cb->args[0];
425         int fams_to_skip = cb->args[1];
426
427         if (chains_to_skip != 0)
428                 genl_lock();
429
430         for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
431                 if (i < chains_to_skip)
432                         continue;
433                 n = 0;
434                 list_for_each_entry(rt, genl_family_chain(i), family_list) {
435                         if (++n < fams_to_skip)
436                                 continue;
437                         if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).pid,
438                                            cb->nlh->nlmsg_seq, NLM_F_MULTI,
439                                            skb, CTRL_CMD_NEWFAMILY) < 0)
440                                 goto errout;
441                 }
442
443                 fams_to_skip = 0;
444         }
445
446 errout:
447         if (chains_to_skip != 0)
448                 genl_unlock();
449
450         cb->args[0] = i;
451         cb->args[1] = n;
452
453         return skb->len;
454 }
455
456 static struct sk_buff *ctrl_build_msg(struct genl_family *family, u32 pid,
457                                       int seq, u8 cmd)
458 {
459         struct sk_buff *skb;
460         int err;
461
462         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
463         if (skb == NULL)
464                 return ERR_PTR(-ENOBUFS);
465
466         err = ctrl_fill_info(family, pid, seq, 0, skb, cmd);
467         if (err < 0) {
468                 nlmsg_free(skb);
469                 return ERR_PTR(err);
470         }
471
472         return skb;
473 }
474
475 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
476         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
477         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
478                                     .len = GENL_NAMSIZ - 1 },
479 };
480
481 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
482 {
483         struct sk_buff *msg;
484         struct genl_family *res = NULL;
485         int err = -EINVAL;
486
487         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
488                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
489                 res = genl_family_find_byid(id);
490         }
491
492         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
493                 char *name;
494
495                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
496                 res = genl_family_find_byname(name);
497         }
498
499         if (res == NULL) {
500                 err = -ENOENT;
501                 goto errout;
502         }
503
504         msg = ctrl_build_msg(res, info->snd_pid, info->snd_seq,
505                              CTRL_CMD_NEWFAMILY);
506         if (IS_ERR(msg)) {
507                 err = PTR_ERR(msg);
508                 goto errout;
509         }
510
511         err = genlmsg_reply(msg, info);
512 errout:
513         return err;
514 }
515
516 static int genl_ctrl_event(int event, void *data)
517 {
518         struct sk_buff *msg;
519
520         if (genl_sock == NULL)
521                 return 0;
522
523         switch (event) {
524         case CTRL_CMD_NEWFAMILY:
525         case CTRL_CMD_DELFAMILY:
526                 msg = ctrl_build_msg(data, 0, 0, event);
527                 if (IS_ERR(msg))
528                         return PTR_ERR(msg);
529
530                 genlmsg_multicast(msg, 0, GENL_ID_CTRL, GFP_KERNEL);
531                 break;
532         }
533
534         return 0;
535 }
536
537 static struct genl_ops genl_ctrl_ops = {
538         .cmd            = CTRL_CMD_GETFAMILY,
539         .doit           = ctrl_getfamily,
540         .dumpit         = ctrl_dumpfamily,
541         .policy         = ctrl_policy,
542 };
543
544 static int __init genl_init(void)
545 {
546         int i, err;
547
548         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
549                 INIT_LIST_HEAD(&family_ht[i]);
550
551         err = genl_register_family(&genl_ctrl);
552         if (err < 0)
553                 goto errout;
554
555         err = genl_register_ops(&genl_ctrl, &genl_ctrl_ops);
556         if (err < 0)
557                 goto errout_register;
558
559         netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);
560         genl_sock = netlink_kernel_create(NETLINK_GENERIC, GENL_MAX_ID,
561                                           genl_rcv, NULL, THIS_MODULE);
562         if (genl_sock == NULL)
563                 panic("GENL: Cannot initialize generic netlink\n");
564
565         return 0;
566
567 errout_register:
568         genl_unregister_family(&genl_ctrl);
569 errout:
570         panic("GENL: Cannot register controller: %d\n", err);
571 }
572
573 subsys_initcall(genl_init);
574
575 EXPORT_SYMBOL(genl_sock);
576 EXPORT_SYMBOL(genl_register_ops);
577 EXPORT_SYMBOL(genl_unregister_ops);
578 EXPORT_SYMBOL(genl_register_family);
579 EXPORT_SYMBOL(genl_unregister_family);