287cfcc56951a86d145bd442a5dd7e9229de44e5
[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/config.h>
9 #include <linux/module.h>
10 #include <linux/kernel.h>
11 #include <linux/errno.h>
12 #include <linux/types.h>
13 #include <linux/socket.h>
14 #include <linux/string.h>
15 #include <linux/skbuff.h>
16 #include <net/sock.h>
17 #include <net/genetlink.h>
18
19 struct sock *genl_sock = NULL;
20
21 static DECLARE_MUTEX(genl_sem); /* serialization of message processing */
22
23 static void genl_lock(void)
24 {
25         down(&genl_sem);
26 }
27
28 static int genl_trylock(void)
29 {
30         return down_trylock(&genl_sem);
31 }
32
33 static void genl_unlock(void)
34 {
35         up(&genl_sem);
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         genl_lock();
147         list_add_tail(&ops->ops_list, &family->ops_list);
148         genl_unlock();
149
150         genl_ctrl_event(CTRL_CMD_NEWOPS, ops);
151         err = 0;
152 errout:
153         return err;
154 }
155
156 /**
157  * genl_unregister_ops - unregister generic netlink operations
158  * @family: generic netlink family
159  * @ops: operations to be unregistered
160  *
161  * Unregisters the specified operations and unassigns them from the
162  * specified family. The operation blocks until the current message
163  * processing has finished and doesn't start again until the
164  * unregister process has finished.
165  *
166  * Note: It is not necessary to unregister all operations before
167  *       unregistering the family, unregistering the family will cause
168  *       all assigned operations to be unregistered automatically.
169  *
170  * Returns 0 on success or a negative error code.
171  */
172 int genl_unregister_ops(struct genl_family *family, struct genl_ops *ops)
173 {
174         struct genl_ops *rc;
175
176         genl_lock();
177         list_for_each_entry(rc, &family->ops_list, ops_list) {
178                 if (rc == ops) {
179                         list_del(&ops->ops_list);
180                         genl_unlock();
181                         genl_ctrl_event(CTRL_CMD_DELOPS, ops);
182                         return 0;
183                 }
184         }
185         genl_unlock();
186
187         return -ENOENT;
188 }
189
190 /**
191  * genl_register_family - register a generic netlink family
192  * @family: generic netlink family
193  *
194  * Registers the specified family after validating it first. Only one
195  * family may be registered with the same family name or identifier.
196  * The family id may equal GENL_ID_GENERATE causing an unique id to
197  * be automatically generated and assigned.
198  *
199  * Return 0 on success or a negative error code.
200  */
201 int genl_register_family(struct genl_family *family)
202 {
203         int err = -EINVAL;
204
205         if (family->id && family->id < GENL_MIN_ID)
206                 goto errout;
207
208         if (family->id > GENL_MAX_ID)
209                 goto errout;
210
211         INIT_LIST_HEAD(&family->ops_list);
212
213         genl_lock();
214
215         if (genl_family_find_byname(family->name)) {
216                 err = -EEXIST;
217                 goto errout_locked;
218         }
219
220         if (genl_family_find_byid(family->id)) {
221                 err = -EEXIST;
222                 goto errout_locked;
223         }
224
225         if (!try_module_get(family->owner)) {
226                 err = -EBUSY;
227                 goto errout_locked;
228         }
229
230         if (family->id == GENL_ID_GENERATE) {
231                 u16 newid = genl_generate_id();
232
233                 if (!newid) {
234                         err = -ENOMEM;
235                         goto errout_locked;
236                 }
237
238                 family->id = newid;
239         }
240
241         if (family->maxattr) {
242                 family->attrbuf = kmalloc((family->maxattr+1) *
243                                         sizeof(struct nlattr *), GFP_KERNEL);
244                 if (family->attrbuf == NULL) {
245                         err = -ENOMEM;
246                         goto errout;
247                 }
248         } else
249                 family->attrbuf = NULL;
250
251         list_add_tail(&family->family_list, genl_family_chain(family->id));
252         genl_unlock();
253
254         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);
255
256         return 0;
257
258 errout_locked:
259         genl_unlock();
260 errout:
261         return err;
262 }
263
264 /**
265  * genl_unregister_family - unregister generic netlink family
266  * @family: generic netlink family
267  *
268  * Unregisters the specified family.
269  *
270  * Returns 0 on success or a negative error code.
271  */
272 int genl_unregister_family(struct genl_family *family)
273 {
274         struct genl_family *rc;
275
276         genl_lock();
277
278         list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
279                 if (family->id != rc->id || strcmp(rc->name, family->name))
280                         continue;
281
282                 list_del(&rc->family_list);
283                 INIT_LIST_HEAD(&family->ops_list);
284                 genl_unlock();
285
286                 module_put(family->owner);
287                 kfree(family->attrbuf);
288                 genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
289                 return 0;
290         }
291
292         genl_unlock();
293
294         return -ENOENT;
295 }
296
297 static inline int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
298                                int *errp)
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 = -EINVAL;
305
306         if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
307                 goto ignore;
308
309         if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
310                 goto ignore;
311
312         family = genl_family_find_byid(nlh->nlmsg_type);
313         if (family == NULL) {
314                 err = -ENOENT;
315                 goto errout;
316         }
317
318         hdrlen = GENL_HDRLEN + family->hdrsize;
319         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
320                 goto errout;
321
322         ops = genl_get_cmd(hdr->cmd, family);
323         if (ops == NULL) {
324                 err = -EOPNOTSUPP;
325                 goto errout;
326         }
327
328         if ((ops->flags & GENL_ADMIN_PERM) && security_netlink_recv(skb)) {
329                 err = -EPERM;
330                 goto errout;
331         }
332
333         if (nlh->nlmsg_flags & NLM_F_DUMP) {
334                 if (ops->dumpit == NULL) {
335                         err = -EOPNOTSUPP;
336                         goto errout;
337                 }
338
339                 *errp = err = netlink_dump_start(genl_sock, skb, nlh,
340                                                  ops->dumpit, NULL);
341                 if (err == 0)
342                         skb_pull(skb, min(NLMSG_ALIGN(nlh->nlmsg_len),
343                                           skb->len));
344                 return -1;
345         }
346
347         if (ops->doit == NULL) {
348                 err = -EOPNOTSUPP;
349                 goto errout;
350         }
351
352         if (family->attrbuf) {
353                 err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr,
354                                   ops->policy);
355                 if (err < 0)
356                         goto errout;
357         }
358
359         info.snd_seq = nlh->nlmsg_seq;
360         info.snd_pid = NETLINK_CB(skb).pid;
361         info.nlhdr = nlh;
362         info.genlhdr = nlmsg_data(nlh);
363         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
364         info.attrs = family->attrbuf;
365
366         *errp = err = ops->doit(skb, &info);
367         return err;
368
369 ignore:
370         return 0;
371
372 errout:
373         *errp = err;
374         return -1;
375 }
376
377 static void genl_rcv(struct sock *sk, int len)
378 {
379         unsigned int qlen = 0;
380
381         do {
382                 if (genl_trylock())
383                         return;
384                 netlink_run_queue(sk, &qlen, &genl_rcv_msg);
385                 genl_unlock();
386         } while (qlen && genl_sock && genl_sock->sk_receive_queue.qlen);
387 }
388
389 /**************************************************************************
390  * Controller
391  **************************************************************************/
392
393 static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
394                           u32 flags, struct sk_buff *skb, u8 cmd)
395 {
396         void *hdr;
397
398         hdr = genlmsg_put(skb, pid, seq, GENL_ID_CTRL, 0, flags, cmd,
399                           family->version);
400         if (hdr == NULL)
401                 return -1;
402
403         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, family->name);
404         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, family->id);
405
406         return genlmsg_end(skb, hdr);
407
408 nla_put_failure:
409         return genlmsg_cancel(skb, hdr);
410 }
411
412 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
413 {
414
415         int i, n = 0;
416         struct genl_family *rt;
417         int chains_to_skip = cb->args[0];
418         int fams_to_skip = cb->args[1];
419
420         for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
421                 if (i < chains_to_skip)
422                         continue;
423                 n = 0;
424                 list_for_each_entry(rt, genl_family_chain(i), family_list) {
425                         if (++n < fams_to_skip)
426                                 continue;
427                         if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).pid,
428                                            cb->nlh->nlmsg_seq, NLM_F_MULTI,
429                                            skb, CTRL_CMD_NEWFAMILY) < 0)
430                                 goto errout;
431                 }
432
433                 fams_to_skip = 0;
434         }
435
436 errout:
437         cb->args[0] = i;
438         cb->args[1] = n;
439
440         return skb->len;
441 }
442
443 static struct sk_buff *ctrl_build_msg(struct genl_family *family, u32 pid,
444                                       int seq, int cmd)
445 {
446         struct sk_buff *skb;
447         int err;
448
449         skb = nlmsg_new(NLMSG_GOODSIZE);
450         if (skb == NULL)
451                 return ERR_PTR(-ENOBUFS);
452
453         err = ctrl_fill_info(family, pid, seq, 0, skb, cmd);
454         if (err < 0) {
455                 nlmsg_free(skb);
456                 return ERR_PTR(err);
457         }
458
459         return skb;
460 }
461
462 static struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] __read_mostly = {
463         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
464         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_STRING },
465 };
466
467 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
468 {
469         struct sk_buff *msg;
470         struct genl_family *res = NULL;
471         int err = -EINVAL;
472
473         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
474                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
475                 res = genl_family_find_byid(id);
476         }
477
478         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
479                 char name[GENL_NAMSIZ];
480
481                 if (nla_strlcpy(name, info->attrs[CTRL_ATTR_FAMILY_NAME],
482                                 GENL_NAMSIZ) >= GENL_NAMSIZ)
483                         goto errout;
484
485                 res = genl_family_find_byname(name);
486         }
487
488         if (res == NULL) {
489                 err = -ENOENT;
490                 goto errout;
491         }
492
493         msg = ctrl_build_msg(res, info->snd_pid, info->snd_seq,
494                              CTRL_CMD_NEWFAMILY);
495         if (IS_ERR(msg)) {
496                 err = PTR_ERR(msg);
497                 goto errout;
498         }
499
500         err = genlmsg_unicast(msg, info->snd_pid);
501 errout:
502         return err;
503 }
504
505 static int genl_ctrl_event(int event, void *data)
506 {
507         struct sk_buff *msg;
508
509         if (genl_sock == NULL)
510                 return 0;
511
512         switch (event) {
513         case CTRL_CMD_NEWFAMILY:
514         case CTRL_CMD_DELFAMILY:
515                 msg = ctrl_build_msg(data, 0, 0, event);
516                 if (IS_ERR(msg))
517                         return PTR_ERR(msg);
518
519                 genlmsg_multicast(msg, 0, GENL_ID_CTRL);
520                 break;
521         }
522
523         return 0;
524 }
525
526 static struct genl_ops genl_ctrl_ops = {
527         .cmd            = CTRL_CMD_GETFAMILY,
528         .doit           = ctrl_getfamily,
529         .dumpit         = ctrl_dumpfamily,
530         .policy         = ctrl_policy,
531 };
532
533 static struct genl_family genl_ctrl = {
534         .id = GENL_ID_CTRL,
535         .name = "nlctrl",
536         .version = 0x1,
537         .maxattr = CTRL_ATTR_MAX,
538         .owner = THIS_MODULE,
539 };
540
541 static int __init genl_init(void)
542 {
543         int i, err;
544
545         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
546                 INIT_LIST_HEAD(&family_ht[i]);
547
548         err = genl_register_family(&genl_ctrl);
549         if (err < 0)
550                 goto errout;
551
552         err = genl_register_ops(&genl_ctrl, &genl_ctrl_ops);
553         if (err < 0)
554                 goto errout_register;
555
556         netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);
557         genl_sock = netlink_kernel_create(NETLINK_GENERIC, GENL_MAX_ID,
558                                           genl_rcv, THIS_MODULE);
559         if (genl_sock == NULL) {
560                 panic("GENL: Cannot initialize generic netlink\n");
561                 return -ENOMEM;
562         }
563
564         return 0;
565
566 errout_register:
567         genl_unregister_family(&genl_ctrl);
568 errout:
569         panic("GENL: Cannot register controller: %d\n", err);
570         return 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);