netlink: genl: fix circular locking
[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  *                              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                 genl_unlock();
448                 err = netlink_dump_start(genl_sock, skb, nlh,
449                                          ops->dumpit, ops->done);
450                 genl_lock();
451                 return err;
452         }
453
454         if (ops->doit == NULL)
455                 return -EOPNOTSUPP;
456
457         if (family->attrbuf) {
458                 err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr,
459                                   ops->policy);
460                 if (err < 0)
461                         return err;
462         }
463
464         info.snd_seq = nlh->nlmsg_seq;
465         info.snd_pid = NETLINK_CB(skb).pid;
466         info.nlhdr = nlh;
467         info.genlhdr = nlmsg_data(nlh);
468         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
469         info.attrs = family->attrbuf;
470
471         return ops->doit(skb, &info);
472 }
473
474 static void genl_rcv(struct sk_buff *skb)
475 {
476         genl_lock();
477         netlink_rcv_skb(skb, &genl_rcv_msg);
478         genl_unlock();
479 }
480
481 /**************************************************************************
482  * Controller
483  **************************************************************************/
484
485 static struct genl_family genl_ctrl = {
486         .id = GENL_ID_CTRL,
487         .name = "nlctrl",
488         .version = 0x2,
489         .maxattr = CTRL_ATTR_MAX,
490 };
491
492 static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
493                           u32 flags, struct sk_buff *skb, u8 cmd)
494 {
495         void *hdr;
496
497         hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
498         if (hdr == NULL)
499                 return -1;
500
501         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, family->name);
502         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, family->id);
503         NLA_PUT_U32(skb, CTRL_ATTR_VERSION, family->version);
504         NLA_PUT_U32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize);
505         NLA_PUT_U32(skb, CTRL_ATTR_MAXATTR, family->maxattr);
506
507         if (!list_empty(&family->ops_list)) {
508                 struct nlattr *nla_ops;
509                 struct genl_ops *ops;
510                 int idx = 1;
511
512                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
513                 if (nla_ops == NULL)
514                         goto nla_put_failure;
515
516                 list_for_each_entry(ops, &family->ops_list, ops_list) {
517                         struct nlattr *nest;
518
519                         nest = nla_nest_start(skb, idx++);
520                         if (nest == NULL)
521                                 goto nla_put_failure;
522
523                         NLA_PUT_U32(skb, CTRL_ATTR_OP_ID, ops->cmd);
524                         NLA_PUT_U32(skb, CTRL_ATTR_OP_FLAGS, ops->flags);
525
526                         nla_nest_end(skb, nest);
527                 }
528
529                 nla_nest_end(skb, nla_ops);
530         }
531
532         if (!list_empty(&family->mcast_groups)) {
533                 struct genl_multicast_group *grp;
534                 struct nlattr *nla_grps;
535                 int idx = 1;
536
537                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
538                 if (nla_grps == NULL)
539                         goto nla_put_failure;
540
541                 list_for_each_entry(grp, &family->mcast_groups, list) {
542                         struct nlattr *nest;
543
544                         nest = nla_nest_start(skb, idx++);
545                         if (nest == NULL)
546                                 goto nla_put_failure;
547
548                         NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
549                         NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
550                                        grp->name);
551
552                         nla_nest_end(skb, nest);
553                 }
554                 nla_nest_end(skb, nla_grps);
555         }
556
557         return genlmsg_end(skb, hdr);
558
559 nla_put_failure:
560         genlmsg_cancel(skb, hdr);
561         return -EMSGSIZE;
562 }
563
564 static int ctrl_fill_mcgrp_info(struct genl_multicast_group *grp, u32 pid,
565                                 u32 seq, u32 flags, struct sk_buff *skb,
566                                 u8 cmd)
567 {
568         void *hdr;
569         struct nlattr *nla_grps;
570         struct nlattr *nest;
571
572         hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
573         if (hdr == NULL)
574                 return -1;
575
576         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, grp->family->name);
577         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, grp->family->id);
578
579         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
580         if (nla_grps == NULL)
581                 goto nla_put_failure;
582
583         nest = nla_nest_start(skb, 1);
584         if (nest == NULL)
585                 goto nla_put_failure;
586
587         NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
588         NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
589                        grp->name);
590
591         nla_nest_end(skb, nest);
592         nla_nest_end(skb, nla_grps);
593
594         return genlmsg_end(skb, hdr);
595
596 nla_put_failure:
597         genlmsg_cancel(skb, hdr);
598         return -EMSGSIZE;
599 }
600
601 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
602 {
603
604         int i, n = 0;
605         struct genl_family *rt;
606         int chains_to_skip = cb->args[0];
607         int fams_to_skip = cb->args[1];
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         cb->args[0] = i;
627         cb->args[1] = n;
628
629         return skb->len;
630 }
631
632 static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
633                                              u32 pid, int seq, u8 cmd)
634 {
635         struct sk_buff *skb;
636         int err;
637
638         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
639         if (skb == NULL)
640                 return ERR_PTR(-ENOBUFS);
641
642         err = ctrl_fill_info(family, pid, seq, 0, skb, cmd);
643         if (err < 0) {
644                 nlmsg_free(skb);
645                 return ERR_PTR(err);
646         }
647
648         return skb;
649 }
650
651 static struct sk_buff *ctrl_build_mcgrp_msg(struct genl_multicast_group *grp,
652                                             u32 pid, int seq, u8 cmd)
653 {
654         struct sk_buff *skb;
655         int err;
656
657         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
658         if (skb == NULL)
659                 return ERR_PTR(-ENOBUFS);
660
661         err = ctrl_fill_mcgrp_info(grp, pid, seq, 0, skb, cmd);
662         if (err < 0) {
663                 nlmsg_free(skb);
664                 return ERR_PTR(err);
665         }
666
667         return skb;
668 }
669
670 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
671         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
672         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
673                                     .len = GENL_NAMSIZ - 1 },
674 };
675
676 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
677 {
678         struct sk_buff *msg;
679         struct genl_family *res = NULL;
680         int err = -EINVAL;
681
682         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
683                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
684                 res = genl_family_find_byid(id);
685         }
686
687         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
688                 char *name;
689
690                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
691                 res = genl_family_find_byname(name);
692         }
693
694         if (res == NULL) {
695                 err = -ENOENT;
696                 goto errout;
697         }
698
699         msg = ctrl_build_family_msg(res, info->snd_pid, info->snd_seq,
700                                     CTRL_CMD_NEWFAMILY);
701         if (IS_ERR(msg)) {
702                 err = PTR_ERR(msg);
703                 goto errout;
704         }
705
706         err = genlmsg_reply(msg, info);
707 errout:
708         return err;
709 }
710
711 static int genl_ctrl_event(int event, void *data)
712 {
713         struct sk_buff *msg;
714
715         if (genl_sock == NULL)
716                 return 0;
717
718         switch (event) {
719         case CTRL_CMD_NEWFAMILY:
720         case CTRL_CMD_DELFAMILY:
721                 msg = ctrl_build_family_msg(data, 0, 0, event);
722                 if (IS_ERR(msg))
723                         return PTR_ERR(msg);
724
725                 genlmsg_multicast(msg, 0, GENL_ID_CTRL, GFP_KERNEL);
726                 break;
727         case CTRL_CMD_NEWMCAST_GRP:
728         case CTRL_CMD_DELMCAST_GRP:
729                 msg = ctrl_build_mcgrp_msg(data, 0, 0, event);
730                 if (IS_ERR(msg))
731                         return PTR_ERR(msg);
732
733                 genlmsg_multicast(msg, 0, GENL_ID_CTRL, GFP_KERNEL);
734                 break;
735         }
736
737         return 0;
738 }
739
740 static struct genl_ops genl_ctrl_ops = {
741         .cmd            = CTRL_CMD_GETFAMILY,
742         .doit           = ctrl_getfamily,
743         .dumpit         = ctrl_dumpfamily,
744         .policy         = ctrl_policy,
745 };
746
747 static struct genl_multicast_group notify_grp = {
748         .name           = "notify",
749 };
750
751 static int __init genl_init(void)
752 {
753         int i, err;
754
755         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
756                 INIT_LIST_HEAD(&family_ht[i]);
757
758         err = genl_register_family(&genl_ctrl);
759         if (err < 0)
760                 goto errout;
761
762         err = genl_register_ops(&genl_ctrl, &genl_ctrl_ops);
763         if (err < 0)
764                 goto errout_register;
765
766         netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);
767
768         /* we'll bump the group number right afterwards */
769         genl_sock = netlink_kernel_create(&init_net, NETLINK_GENERIC, 0,
770                                           genl_rcv, &genl_mutex, THIS_MODULE);
771         if (genl_sock == NULL)
772                 panic("GENL: Cannot initialize generic netlink\n");
773
774         err = genl_register_mc_group(&genl_ctrl, &notify_grp);
775         if (err < 0)
776                 goto errout_register;
777
778         return 0;
779
780 errout_register:
781         genl_unregister_family(&genl_ctrl);
782 errout:
783         panic("GENL: Cannot register controller: %d\n", err);
784 }
785
786 subsys_initcall(genl_init);
787
788 EXPORT_SYMBOL(genl_sock);
789 EXPORT_SYMBOL(genl_register_ops);
790 EXPORT_SYMBOL(genl_unregister_ops);
791 EXPORT_SYMBOL(genl_register_family);
792 EXPORT_SYMBOL(genl_unregister_family);