xref: /openbmc/linux/net/netlink/genetlink.c (revision 732a675a)
1 /*
2  * NETLINK      Generic Netlink Family
3  *
4  * 		Authors:	Jamal Hadi Salim
5  * 				Thomas Graf <tgraf@suug.ch>
6  *				Johannes Berg <johannes@sipsolutions.net>
7  */
8 
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 <linux/mutex.h>
17 #include <linux/bitmap.h>
18 #include <net/sock.h>
19 #include <net/genetlink.h>
20 
21 struct sock *genl_sock = NULL;
22 
23 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
24 
25 static inline void genl_lock(void)
26 {
27 	mutex_lock(&genl_mutex);
28 }
29 
30 static inline void genl_unlock(void)
31 {
32 	mutex_unlock(&genl_mutex);
33 }
34 
35 #define GENL_FAM_TAB_SIZE	16
36 #define GENL_FAM_TAB_MASK	(GENL_FAM_TAB_SIZE - 1)
37 
38 static struct list_head family_ht[GENL_FAM_TAB_SIZE];
39 /*
40  * Bitmap of multicast groups that are currently in use.
41  *
42  * To avoid an allocation at boot of just one unsigned long,
43  * declare it global instead.
44  * Bit 0 is marked as already used since group 0 is invalid.
45  */
46 static unsigned long mc_group_start = 0x1;
47 static unsigned long *mc_groups = &mc_group_start;
48 static unsigned long mc_groups_longs = 1;
49 
50 static int genl_ctrl_event(int event, void *data);
51 
52 static inline unsigned int genl_family_hash(unsigned int id)
53 {
54 	return id & GENL_FAM_TAB_MASK;
55 }
56 
57 static inline struct list_head *genl_family_chain(unsigned int id)
58 {
59 	return &family_ht[genl_family_hash(id)];
60 }
61 
62 static struct genl_family *genl_family_find_byid(unsigned int id)
63 {
64 	struct genl_family *f;
65 
66 	list_for_each_entry(f, genl_family_chain(id), family_list)
67 		if (f->id == id)
68 			return f;
69 
70 	return NULL;
71 }
72 
73 static struct genl_family *genl_family_find_byname(char *name)
74 {
75 	struct genl_family *f;
76 	int i;
77 
78 	for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
79 		list_for_each_entry(f, genl_family_chain(i), family_list)
80 			if (strcmp(f->name, name) == 0)
81 				return f;
82 
83 	return NULL;
84 }
85 
86 static struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
87 {
88 	struct genl_ops *ops;
89 
90 	list_for_each_entry(ops, &family->ops_list, ops_list)
91 		if (ops->cmd == cmd)
92 			return ops;
93 
94 	return NULL;
95 }
96 
97 /* Of course we are going to have problems once we hit
98  * 2^16 alive types, but that can only happen by year 2K
99 */
100 static inline u16 genl_generate_id(void)
101 {
102 	static u16 id_gen_idx;
103 	int overflowed = 0;
104 
105 	do {
106 		if (id_gen_idx == 0)
107 			id_gen_idx = GENL_MIN_ID;
108 
109 		if (++id_gen_idx > GENL_MAX_ID) {
110 			if (!overflowed) {
111 				overflowed = 1;
112 				id_gen_idx = 0;
113 				continue;
114 			} else
115 				return 0;
116 		}
117 
118 	} while (genl_family_find_byid(id_gen_idx));
119 
120 	return id_gen_idx;
121 }
122 
123 static struct genl_multicast_group notify_grp;
124 
125 /**
126  * genl_register_mc_group - register a multicast group
127  *
128  * Registers the specified multicast group and notifies userspace
129  * about the new group.
130  *
131  * Returns 0 on success or a negative error code.
132  *
133  * @family: The generic netlink family the group shall be registered for.
134  * @grp: The group to register, must have a name.
135  */
136 int genl_register_mc_group(struct genl_family *family,
137 			   struct genl_multicast_group *grp)
138 {
139 	int id;
140 	unsigned long *new_groups;
141 	int err;
142 
143 	BUG_ON(grp->name[0] == '\0');
144 
145 	genl_lock();
146 
147 	/* special-case our own group */
148 	if (grp == &notify_grp)
149 		id = GENL_ID_CTRL;
150 	else
151 		id = find_first_zero_bit(mc_groups,
152 					 mc_groups_longs * BITS_PER_LONG);
153 
154 
155 	if (id >= mc_groups_longs * BITS_PER_LONG) {
156 		size_t nlen = (mc_groups_longs + 1) * sizeof(unsigned long);
157 
158 		if (mc_groups == &mc_group_start) {
159 			new_groups = kzalloc(nlen, GFP_KERNEL);
160 			if (!new_groups) {
161 				err = -ENOMEM;
162 				goto out;
163 			}
164 			mc_groups = new_groups;
165 			*mc_groups = mc_group_start;
166 		} else {
167 			new_groups = krealloc(mc_groups, nlen, GFP_KERNEL);
168 			if (!new_groups) {
169 				err = -ENOMEM;
170 				goto out;
171 			}
172 			mc_groups = new_groups;
173 			mc_groups[mc_groups_longs] = 0;
174 		}
175 		mc_groups_longs++;
176 	}
177 
178 	err = netlink_change_ngroups(genl_sock,
179 				     mc_groups_longs * BITS_PER_LONG);
180 	if (err)
181 		goto out;
182 
183 	grp->id = id;
184 	set_bit(id, mc_groups);
185 	list_add_tail(&grp->list, &family->mcast_groups);
186 	grp->family = family;
187 
188 	genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, grp);
189  out:
190 	genl_unlock();
191 	return err;
192 }
193 EXPORT_SYMBOL(genl_register_mc_group);
194 
195 static void __genl_unregister_mc_group(struct genl_family *family,
196 				       struct genl_multicast_group *grp)
197 {
198 	BUG_ON(grp->family != family);
199 	netlink_clear_multicast_users(genl_sock, grp->id);
200 	clear_bit(grp->id, mc_groups);
201 	list_del(&grp->list);
202 	genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, grp);
203 	grp->id = 0;
204 	grp->family = NULL;
205 }
206 
207 /**
208  * genl_unregister_mc_group - unregister a multicast group
209  *
210  * Unregisters the specified multicast group and notifies userspace
211  * about it. All current listeners on the group are removed.
212  *
213  * Note: It is not necessary to unregister all multicast groups before
214  *       unregistering the family, unregistering the family will cause
215  *       all assigned multicast groups to be unregistered automatically.
216  *
217  * @family: Generic netlink family the group belongs to.
218  * @grp: The group to unregister, must have been registered successfully
219  *	 previously.
220  */
221 void genl_unregister_mc_group(struct genl_family *family,
222 			      struct genl_multicast_group *grp)
223 {
224 	genl_lock();
225 	__genl_unregister_mc_group(family, grp);
226 	genl_unlock();
227 }
228 
229 static void genl_unregister_mc_groups(struct genl_family *family)
230 {
231 	struct genl_multicast_group *grp, *tmp;
232 
233 	list_for_each_entry_safe(grp, tmp, &family->mcast_groups, list)
234 		__genl_unregister_mc_group(family, grp);
235 }
236 
237 /**
238  * genl_register_ops - register generic netlink operations
239  * @family: generic netlink family
240  * @ops: operations to be registered
241  *
242  * Registers the specified operations and assigns them to the specified
243  * family. Either a doit or dumpit callback must be specified or the
244  * operation will fail. Only one operation structure per command
245  * identifier may be registered.
246  *
247  * See include/net/genetlink.h for more documenation on the operations
248  * structure.
249  *
250  * Returns 0 on success or a negative error code.
251  */
252 int genl_register_ops(struct genl_family *family, struct genl_ops *ops)
253 {
254 	int err = -EINVAL;
255 
256 	if (ops->dumpit == NULL && ops->doit == NULL)
257 		goto errout;
258 
259 	if (genl_get_cmd(ops->cmd, family)) {
260 		err = -EEXIST;
261 		goto errout;
262 	}
263 
264 	if (ops->dumpit)
265 		ops->flags |= GENL_CMD_CAP_DUMP;
266 	if (ops->doit)
267 		ops->flags |= GENL_CMD_CAP_DO;
268 	if (ops->policy)
269 		ops->flags |= GENL_CMD_CAP_HASPOL;
270 
271 	genl_lock();
272 	list_add_tail(&ops->ops_list, &family->ops_list);
273 	genl_unlock();
274 
275 	genl_ctrl_event(CTRL_CMD_NEWOPS, ops);
276 	err = 0;
277 errout:
278 	return err;
279 }
280 
281 /**
282  * genl_unregister_ops - unregister generic netlink operations
283  * @family: generic netlink family
284  * @ops: operations to be unregistered
285  *
286  * Unregisters the specified operations and unassigns them from the
287  * specified family. The operation blocks until the current message
288  * processing has finished and doesn't start again until the
289  * unregister process has finished.
290  *
291  * Note: It is not necessary to unregister all operations before
292  *       unregistering the family, unregistering the family will cause
293  *       all assigned operations to be unregistered automatically.
294  *
295  * Returns 0 on success or a negative error code.
296  */
297 int genl_unregister_ops(struct genl_family *family, struct genl_ops *ops)
298 {
299 	struct genl_ops *rc;
300 
301 	genl_lock();
302 	list_for_each_entry(rc, &family->ops_list, ops_list) {
303 		if (rc == ops) {
304 			list_del(&ops->ops_list);
305 			genl_unlock();
306 			genl_ctrl_event(CTRL_CMD_DELOPS, ops);
307 			return 0;
308 		}
309 	}
310 	genl_unlock();
311 
312 	return -ENOENT;
313 }
314 
315 /**
316  * genl_register_family - register a generic netlink family
317  * @family: generic netlink family
318  *
319  * Registers the specified family after validating it first. Only one
320  * family may be registered with the same family name or identifier.
321  * The family id may equal GENL_ID_GENERATE causing an unique id to
322  * be automatically generated and assigned.
323  *
324  * Return 0 on success or a negative error code.
325  */
326 int genl_register_family(struct genl_family *family)
327 {
328 	int err = -EINVAL;
329 
330 	if (family->id && family->id < GENL_MIN_ID)
331 		goto errout;
332 
333 	if (family->id > GENL_MAX_ID)
334 		goto errout;
335 
336 	INIT_LIST_HEAD(&family->ops_list);
337 	INIT_LIST_HEAD(&family->mcast_groups);
338 
339 	genl_lock();
340 
341 	if (genl_family_find_byname(family->name)) {
342 		err = -EEXIST;
343 		goto errout_locked;
344 	}
345 
346 	if (genl_family_find_byid(family->id)) {
347 		err = -EEXIST;
348 		goto errout_locked;
349 	}
350 
351 	if (family->id == GENL_ID_GENERATE) {
352 		u16 newid = genl_generate_id();
353 
354 		if (!newid) {
355 			err = -ENOMEM;
356 			goto errout_locked;
357 		}
358 
359 		family->id = newid;
360 	}
361 
362 	if (family->maxattr) {
363 		family->attrbuf = kmalloc((family->maxattr+1) *
364 					sizeof(struct nlattr *), GFP_KERNEL);
365 		if (family->attrbuf == NULL) {
366 			err = -ENOMEM;
367 			goto errout_locked;
368 		}
369 	} else
370 		family->attrbuf = NULL;
371 
372 	list_add_tail(&family->family_list, genl_family_chain(family->id));
373 	genl_unlock();
374 
375 	genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);
376 
377 	return 0;
378 
379 errout_locked:
380 	genl_unlock();
381 errout:
382 	return err;
383 }
384 
385 /**
386  * genl_unregister_family - unregister generic netlink family
387  * @family: generic netlink family
388  *
389  * Unregisters the specified family.
390  *
391  * Returns 0 on success or a negative error code.
392  */
393 int genl_unregister_family(struct genl_family *family)
394 {
395 	struct genl_family *rc;
396 
397 	genl_lock();
398 
399 	genl_unregister_mc_groups(family);
400 
401 	list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
402 		if (family->id != rc->id || strcmp(rc->name, family->name))
403 			continue;
404 
405 		list_del(&rc->family_list);
406 		INIT_LIST_HEAD(&family->ops_list);
407 		genl_unlock();
408 
409 		kfree(family->attrbuf);
410 		genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
411 		return 0;
412 	}
413 
414 	genl_unlock();
415 
416 	return -ENOENT;
417 }
418 
419 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
420 {
421 	struct genl_ops *ops;
422 	struct genl_family *family;
423 	struct genl_info info;
424 	struct genlmsghdr *hdr = nlmsg_data(nlh);
425 	int hdrlen, err;
426 
427 	family = genl_family_find_byid(nlh->nlmsg_type);
428 	if (family == NULL)
429 		return -ENOENT;
430 
431 	hdrlen = GENL_HDRLEN + family->hdrsize;
432 	if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
433 		return -EINVAL;
434 
435 	ops = genl_get_cmd(hdr->cmd, family);
436 	if (ops == NULL)
437 		return -EOPNOTSUPP;
438 
439 	if ((ops->flags & GENL_ADMIN_PERM) &&
440 	    security_netlink_recv(skb, CAP_NET_ADMIN))
441 		return -EPERM;
442 
443 	if (nlh->nlmsg_flags & NLM_F_DUMP) {
444 		if (ops->dumpit == NULL)
445 			return -EOPNOTSUPP;
446 
447 		return netlink_dump_start(genl_sock, skb, nlh,
448 					  ops->dumpit, ops->done);
449 	}
450 
451 	if (ops->doit == NULL)
452 		return -EOPNOTSUPP;
453 
454 	if (family->attrbuf) {
455 		err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr,
456 				  ops->policy);
457 		if (err < 0)
458 			return err;
459 	}
460 
461 	info.snd_seq = nlh->nlmsg_seq;
462 	info.snd_pid = NETLINK_CB(skb).pid;
463 	info.nlhdr = nlh;
464 	info.genlhdr = nlmsg_data(nlh);
465 	info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
466 	info.attrs = family->attrbuf;
467 
468 	return ops->doit(skb, &info);
469 }
470 
471 static void genl_rcv(struct sk_buff *skb)
472 {
473 	genl_lock();
474 	netlink_rcv_skb(skb, &genl_rcv_msg);
475 	genl_unlock();
476 }
477 
478 /**************************************************************************
479  * Controller
480  **************************************************************************/
481 
482 static struct genl_family genl_ctrl = {
483 	.id = GENL_ID_CTRL,
484 	.name = "nlctrl",
485 	.version = 0x2,
486 	.maxattr = CTRL_ATTR_MAX,
487 };
488 
489 static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
490 			  u32 flags, struct sk_buff *skb, u8 cmd)
491 {
492 	void *hdr;
493 
494 	hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
495 	if (hdr == NULL)
496 		return -1;
497 
498 	NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, family->name);
499 	NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, family->id);
500 	NLA_PUT_U32(skb, CTRL_ATTR_VERSION, family->version);
501 	NLA_PUT_U32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize);
502 	NLA_PUT_U32(skb, CTRL_ATTR_MAXATTR, family->maxattr);
503 
504 	if (!list_empty(&family->ops_list)) {
505 		struct nlattr *nla_ops;
506 		struct genl_ops *ops;
507 		int idx = 1;
508 
509 		nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
510 		if (nla_ops == NULL)
511 			goto nla_put_failure;
512 
513 		list_for_each_entry(ops, &family->ops_list, ops_list) {
514 			struct nlattr *nest;
515 
516 			nest = nla_nest_start(skb, idx++);
517 			if (nest == NULL)
518 				goto nla_put_failure;
519 
520 			NLA_PUT_U32(skb, CTRL_ATTR_OP_ID, ops->cmd);
521 			NLA_PUT_U32(skb, CTRL_ATTR_OP_FLAGS, ops->flags);
522 
523 			nla_nest_end(skb, nest);
524 		}
525 
526 		nla_nest_end(skb, nla_ops);
527 	}
528 
529 	if (!list_empty(&family->mcast_groups)) {
530 		struct genl_multicast_group *grp;
531 		struct nlattr *nla_grps;
532 		int idx = 1;
533 
534 		nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
535 		if (nla_grps == NULL)
536 			goto nla_put_failure;
537 
538 		list_for_each_entry(grp, &family->mcast_groups, list) {
539 			struct nlattr *nest;
540 
541 			nest = nla_nest_start(skb, idx++);
542 			if (nest == NULL)
543 				goto nla_put_failure;
544 
545 			NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
546 			NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
547 				       grp->name);
548 
549 			nla_nest_end(skb, nest);
550 		}
551 		nla_nest_end(skb, nla_grps);
552 	}
553 
554 	return genlmsg_end(skb, hdr);
555 
556 nla_put_failure:
557 	genlmsg_cancel(skb, hdr);
558 	return -EMSGSIZE;
559 }
560 
561 static int ctrl_fill_mcgrp_info(struct genl_multicast_group *grp, u32 pid,
562 				u32 seq, u32 flags, struct sk_buff *skb,
563 				u8 cmd)
564 {
565 	void *hdr;
566 	struct nlattr *nla_grps;
567 	struct nlattr *nest;
568 
569 	hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
570 	if (hdr == NULL)
571 		return -1;
572 
573 	NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, grp->family->name);
574 	NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, grp->family->id);
575 
576 	nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
577 	if (nla_grps == NULL)
578 		goto nla_put_failure;
579 
580 	nest = nla_nest_start(skb, 1);
581 	if (nest == NULL)
582 		goto nla_put_failure;
583 
584 	NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
585 	NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
586 		       grp->name);
587 
588 	nla_nest_end(skb, nest);
589 	nla_nest_end(skb, nla_grps);
590 
591 	return genlmsg_end(skb, hdr);
592 
593 nla_put_failure:
594 	genlmsg_cancel(skb, hdr);
595 	return -EMSGSIZE;
596 }
597 
598 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
599 {
600 
601 	int i, n = 0;
602 	struct genl_family *rt;
603 	int chains_to_skip = cb->args[0];
604 	int fams_to_skip = cb->args[1];
605 
606 	if (chains_to_skip != 0)
607 		genl_lock();
608 
609 	for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
610 		if (i < chains_to_skip)
611 			continue;
612 		n = 0;
613 		list_for_each_entry(rt, genl_family_chain(i), family_list) {
614 			if (++n < fams_to_skip)
615 				continue;
616 			if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).pid,
617 					   cb->nlh->nlmsg_seq, NLM_F_MULTI,
618 					   skb, CTRL_CMD_NEWFAMILY) < 0)
619 				goto errout;
620 		}
621 
622 		fams_to_skip = 0;
623 	}
624 
625 errout:
626 	if (chains_to_skip != 0)
627 		genl_unlock();
628 
629 	cb->args[0] = i;
630 	cb->args[1] = n;
631 
632 	return skb->len;
633 }
634 
635 static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
636 					     u32 pid, int seq, u8 cmd)
637 {
638 	struct sk_buff *skb;
639 	int err;
640 
641 	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
642 	if (skb == NULL)
643 		return ERR_PTR(-ENOBUFS);
644 
645 	err = ctrl_fill_info(family, pid, seq, 0, skb, cmd);
646 	if (err < 0) {
647 		nlmsg_free(skb);
648 		return ERR_PTR(err);
649 	}
650 
651 	return skb;
652 }
653 
654 static struct sk_buff *ctrl_build_mcgrp_msg(struct genl_multicast_group *grp,
655 					    u32 pid, int seq, u8 cmd)
656 {
657 	struct sk_buff *skb;
658 	int err;
659 
660 	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
661 	if (skb == NULL)
662 		return ERR_PTR(-ENOBUFS);
663 
664 	err = ctrl_fill_mcgrp_info(grp, pid, seq, 0, skb, cmd);
665 	if (err < 0) {
666 		nlmsg_free(skb);
667 		return ERR_PTR(err);
668 	}
669 
670 	return skb;
671 }
672 
673 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
674 	[CTRL_ATTR_FAMILY_ID]	= { .type = NLA_U16 },
675 	[CTRL_ATTR_FAMILY_NAME]	= { .type = NLA_NUL_STRING,
676 				    .len = GENL_NAMSIZ - 1 },
677 };
678 
679 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
680 {
681 	struct sk_buff *msg;
682 	struct genl_family *res = NULL;
683 	int err = -EINVAL;
684 
685 	if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
686 		u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
687 		res = genl_family_find_byid(id);
688 	}
689 
690 	if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
691 		char *name;
692 
693 		name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
694 		res = genl_family_find_byname(name);
695 	}
696 
697 	if (res == NULL) {
698 		err = -ENOENT;
699 		goto errout;
700 	}
701 
702 	msg = ctrl_build_family_msg(res, info->snd_pid, info->snd_seq,
703 				    CTRL_CMD_NEWFAMILY);
704 	if (IS_ERR(msg)) {
705 		err = PTR_ERR(msg);
706 		goto errout;
707 	}
708 
709 	err = genlmsg_reply(msg, info);
710 errout:
711 	return err;
712 }
713 
714 static int genl_ctrl_event(int event, void *data)
715 {
716 	struct sk_buff *msg;
717 
718 	if (genl_sock == NULL)
719 		return 0;
720 
721 	switch (event) {
722 	case CTRL_CMD_NEWFAMILY:
723 	case CTRL_CMD_DELFAMILY:
724 		msg = ctrl_build_family_msg(data, 0, 0, event);
725 		if (IS_ERR(msg))
726 			return PTR_ERR(msg);
727 
728 		genlmsg_multicast(msg, 0, GENL_ID_CTRL, GFP_KERNEL);
729 		break;
730 	case CTRL_CMD_NEWMCAST_GRP:
731 	case CTRL_CMD_DELMCAST_GRP:
732 		msg = ctrl_build_mcgrp_msg(data, 0, 0, event);
733 		if (IS_ERR(msg))
734 			return PTR_ERR(msg);
735 
736 		genlmsg_multicast(msg, 0, GENL_ID_CTRL, GFP_KERNEL);
737 		break;
738 	}
739 
740 	return 0;
741 }
742 
743 static struct genl_ops genl_ctrl_ops = {
744 	.cmd		= CTRL_CMD_GETFAMILY,
745 	.doit		= ctrl_getfamily,
746 	.dumpit		= ctrl_dumpfamily,
747 	.policy		= ctrl_policy,
748 };
749 
750 static struct genl_multicast_group notify_grp = {
751 	.name		= "notify",
752 };
753 
754 static int __init genl_init(void)
755 {
756 	int i, err;
757 
758 	for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
759 		INIT_LIST_HEAD(&family_ht[i]);
760 
761 	err = genl_register_family(&genl_ctrl);
762 	if (err < 0)
763 		goto errout;
764 
765 	err = genl_register_ops(&genl_ctrl, &genl_ctrl_ops);
766 	if (err < 0)
767 		goto errout_register;
768 
769 	netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);
770 
771 	/* we'll bump the group number right afterwards */
772 	genl_sock = netlink_kernel_create(&init_net, NETLINK_GENERIC, 0,
773 					  genl_rcv, NULL, THIS_MODULE);
774 	if (genl_sock == NULL)
775 		panic("GENL: Cannot initialize generic netlink\n");
776 
777 	err = genl_register_mc_group(&genl_ctrl, &notify_grp);
778 	if (err < 0)
779 		goto errout_register;
780 
781 	return 0;
782 
783 errout_register:
784 	genl_unregister_family(&genl_ctrl);
785 errout:
786 	panic("GENL: Cannot register controller: %d\n", err);
787 }
788 
789 subsys_initcall(genl_init);
790 
791 EXPORT_SYMBOL(genl_sock);
792 EXPORT_SYMBOL(genl_register_ops);
793 EXPORT_SYMBOL(genl_unregister_ops);
794 EXPORT_SYMBOL(genl_register_family);
795 EXPORT_SYMBOL(genl_unregister_family);
796