genetlink: Optimize genl_register_family()
[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 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
22
23 static inline void genl_lock(void)
24 {
25         mutex_lock(&genl_mutex);
26 }
27
28 static inline void genl_unlock(void)
29 {
30         mutex_unlock(&genl_mutex);
31 }
32
33 #define GENL_FAM_TAB_SIZE       16
34 #define GENL_FAM_TAB_MASK       (GENL_FAM_TAB_SIZE - 1)
35
36 static struct list_head family_ht[GENL_FAM_TAB_SIZE];
37 /*
38  * Bitmap of multicast groups that are currently in use.
39  *
40  * To avoid an allocation at boot of just one unsigned long,
41  * declare it global instead.
42  * Bit 0 is marked as already used since group 0 is invalid.
43  */
44 static unsigned long mc_group_start = 0x1;
45 static unsigned long *mc_groups = &mc_group_start;
46 static unsigned long mc_groups_longs = 1;
47
48 static int genl_ctrl_event(int event, void *data);
49
50 static inline unsigned int genl_family_hash(unsigned int id)
51 {
52         return id & GENL_FAM_TAB_MASK;
53 }
54
55 static inline struct list_head *genl_family_chain(unsigned int id)
56 {
57         return &family_ht[genl_family_hash(id)];
58 }
59
60 static struct genl_family *genl_family_find_byid(unsigned int id)
61 {
62         struct genl_family *f;
63
64         list_for_each_entry(f, genl_family_chain(id), family_list)
65                 if (f->id == id)
66                         return f;
67
68         return NULL;
69 }
70
71 static struct genl_family *genl_family_find_byname(char *name)
72 {
73         struct genl_family *f;
74         int i;
75
76         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
77                 list_for_each_entry(f, genl_family_chain(i), family_list)
78                         if (strcmp(f->name, name) == 0)
79                                 return f;
80
81         return NULL;
82 }
83
84 static struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
85 {
86         struct genl_ops *ops;
87
88         list_for_each_entry(ops, &family->ops_list, ops_list)
89                 if (ops->cmd == cmd)
90                         return ops;
91
92         return NULL;
93 }
94
95 /* Of course we are going to have problems once we hit
96  * 2^16 alive types, but that can only happen by year 2K
97 */
98 static inline u16 genl_generate_id(void)
99 {
100         static u16 id_gen_idx;
101         int overflowed = 0;
102
103         do {
104                 if (id_gen_idx == 0)
105                         id_gen_idx = GENL_MIN_ID;
106
107                 if (++id_gen_idx > GENL_MAX_ID) {
108                         if (!overflowed) {
109                                 overflowed = 1;
110                                 id_gen_idx = 0;
111                                 continue;
112                         } else
113                                 return 0;
114                 }
115
116         } while (genl_family_find_byid(id_gen_idx));
117
118         return id_gen_idx;
119 }
120
121 static struct genl_multicast_group notify_grp;
122
123 /**
124  * genl_register_mc_group - register a multicast group
125  *
126  * Registers the specified multicast group and notifies userspace
127  * about the new group.
128  *
129  * Returns 0 on success or a negative error code.
130  *
131  * @family: The generic netlink family the group shall be registered for.
132  * @grp: The group to register, must have a name.
133  */
134 int genl_register_mc_group(struct genl_family *family,
135                            struct genl_multicast_group *grp)
136 {
137         int id;
138         unsigned long *new_groups;
139         int err = 0;
140
141         BUG_ON(grp->name[0] == '\0');
142
143         genl_lock();
144
145         /* special-case our own group */
146         if (grp == &notify_grp)
147                 id = GENL_ID_CTRL;
148         else
149                 id = find_first_zero_bit(mc_groups,
150                                          mc_groups_longs * BITS_PER_LONG);
151
152
153         if (id >= mc_groups_longs * BITS_PER_LONG) {
154                 size_t nlen = (mc_groups_longs + 1) * sizeof(unsigned long);
155
156                 if (mc_groups == &mc_group_start) {
157                         new_groups = kzalloc(nlen, GFP_KERNEL);
158                         if (!new_groups) {
159                                 err = -ENOMEM;
160                                 goto out;
161                         }
162                         mc_groups = new_groups;
163                         *mc_groups = mc_group_start;
164                 } else {
165                         new_groups = krealloc(mc_groups, nlen, GFP_KERNEL);
166                         if (!new_groups) {
167                                 err = -ENOMEM;
168                                 goto out;
169                         }
170                         mc_groups = new_groups;
171                         mc_groups[mc_groups_longs] = 0;
172                 }
173                 mc_groups_longs++;
174         }
175
176         if (family->netnsok) {
177                 struct net *net;
178
179                 netlink_table_grab();
180                 rcu_read_lock();
181                 for_each_net_rcu(net) {
182                         err = __netlink_change_ngroups(net->genl_sock,
183                                         mc_groups_longs * BITS_PER_LONG);
184                         if (err) {
185                                 /*
186                                  * No need to roll back, can only fail if
187                                  * memory allocation fails and then the
188                                  * number of _possible_ groups has been
189                                  * increased on some sockets which is ok.
190                                  */
191                                 rcu_read_unlock();
192                                 netlink_table_ungrab();
193                                 goto out;
194                         }
195                 }
196                 rcu_read_unlock();
197                 netlink_table_ungrab();
198         } else {
199                 err = netlink_change_ngroups(init_net.genl_sock,
200                                              mc_groups_longs * BITS_PER_LONG);
201                 if (err)
202                         goto out;
203         }
204
205         grp->id = id;
206         set_bit(id, mc_groups);
207         list_add_tail(&grp->list, &family->mcast_groups);
208         grp->family = family;
209
210         genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, grp);
211  out:
212         genl_unlock();
213         return err;
214 }
215 EXPORT_SYMBOL(genl_register_mc_group);
216
217 static void __genl_unregister_mc_group(struct genl_family *family,
218                                        struct genl_multicast_group *grp)
219 {
220         struct net *net;
221         BUG_ON(grp->family != family);
222
223         netlink_table_grab();
224         rcu_read_lock();
225         for_each_net_rcu(net)
226                 __netlink_clear_multicast_users(net->genl_sock, grp->id);
227         rcu_read_unlock();
228         netlink_table_ungrab();
229
230         clear_bit(grp->id, mc_groups);
231         list_del(&grp->list);
232         genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, grp);
233         grp->id = 0;
234         grp->family = NULL;
235 }
236
237 /**
238  * genl_unregister_mc_group - unregister a multicast group
239  *
240  * Unregisters the specified multicast group and notifies userspace
241  * about it. All current listeners on the group are removed.
242  *
243  * Note: It is not necessary to unregister all multicast groups before
244  *       unregistering the family, unregistering the family will cause
245  *       all assigned multicast groups to be unregistered automatically.
246  *
247  * @family: Generic netlink family the group belongs to.
248  * @grp: The group to unregister, must have been registered successfully
249  *       previously.
250  */
251 void genl_unregister_mc_group(struct genl_family *family,
252                               struct genl_multicast_group *grp)
253 {
254         genl_lock();
255         __genl_unregister_mc_group(family, grp);
256         genl_unlock();
257 }
258 EXPORT_SYMBOL(genl_unregister_mc_group);
259
260 static void genl_unregister_mc_groups(struct genl_family *family)
261 {
262         struct genl_multicast_group *grp, *tmp;
263
264         list_for_each_entry_safe(grp, tmp, &family->mcast_groups, list)
265                 __genl_unregister_mc_group(family, grp);
266 }
267
268 /**
269  * genl_register_ops - register generic netlink operations
270  * @family: generic netlink family
271  * @ops: operations to be registered
272  *
273  * Registers the specified operations and assigns them to the specified
274  * family. Either a doit or dumpit callback must be specified or the
275  * operation will fail. Only one operation structure per command
276  * identifier may be registered.
277  *
278  * See include/net/genetlink.h for more documenation on the operations
279  * structure.
280  *
281  * Returns 0 on success or a negative error code.
282  */
283 int genl_register_ops(struct genl_family *family, struct genl_ops *ops)
284 {
285         int err = -EINVAL;
286
287         if (ops->dumpit == NULL && ops->doit == NULL)
288                 goto errout;
289
290         if (genl_get_cmd(ops->cmd, family)) {
291                 err = -EEXIST;
292                 goto errout;
293         }
294
295         if (ops->dumpit)
296                 ops->flags |= GENL_CMD_CAP_DUMP;
297         if (ops->doit)
298                 ops->flags |= GENL_CMD_CAP_DO;
299         if (ops->policy)
300                 ops->flags |= GENL_CMD_CAP_HASPOL;
301
302         genl_lock();
303         list_add_tail(&ops->ops_list, &family->ops_list);
304         genl_unlock();
305
306         genl_ctrl_event(CTRL_CMD_NEWOPS, ops);
307         err = 0;
308 errout:
309         return err;
310 }
311
312 /**
313  * genl_unregister_ops - unregister generic netlink operations
314  * @family: generic netlink family
315  * @ops: operations to be unregistered
316  *
317  * Unregisters the specified operations and unassigns them from the
318  * specified family. The operation blocks until the current message
319  * processing has finished and doesn't start again until the
320  * unregister process has finished.
321  *
322  * Note: It is not necessary to unregister all operations before
323  *       unregistering the family, unregistering the family will cause
324  *       all assigned operations to be unregistered automatically.
325  *
326  * Returns 0 on success or a negative error code.
327  */
328 int genl_unregister_ops(struct genl_family *family, struct genl_ops *ops)
329 {
330         struct genl_ops *rc;
331
332         genl_lock();
333         list_for_each_entry(rc, &family->ops_list, ops_list) {
334                 if (rc == ops) {
335                         list_del(&ops->ops_list);
336                         genl_unlock();
337                         genl_ctrl_event(CTRL_CMD_DELOPS, ops);
338                         return 0;
339                 }
340         }
341         genl_unlock();
342
343         return -ENOENT;
344 }
345
346 /**
347  * genl_register_family - register a generic netlink family
348  * @family: generic netlink family
349  *
350  * Registers the specified family after validating it first. Only one
351  * family may be registered with the same family name or identifier.
352  * The family id may equal GENL_ID_GENERATE causing an unique id to
353  * be automatically generated and assigned.
354  *
355  * Return 0 on success or a negative error code.
356  */
357 int genl_register_family(struct genl_family *family)
358 {
359         int err = -EINVAL;
360
361         if (family->id && family->id < GENL_MIN_ID)
362                 goto errout;
363
364         if (family->id > GENL_MAX_ID)
365                 goto errout;
366
367         INIT_LIST_HEAD(&family->ops_list);
368         INIT_LIST_HEAD(&family->mcast_groups);
369
370         genl_lock();
371
372         if (genl_family_find_byname(family->name)) {
373                 err = -EEXIST;
374                 goto errout_locked;
375         }
376
377         if (family->id == GENL_ID_GENERATE) {
378                 u16 newid = genl_generate_id();
379
380                 if (!newid) {
381                         err = -ENOMEM;
382                         goto errout_locked;
383                 }
384
385                 family->id = newid;
386         } else if (genl_family_find_byid(family->id)) {
387                 err = -EEXIST;
388                 goto errout_locked;
389         }
390
391         if (family->maxattr) {
392                 family->attrbuf = kmalloc((family->maxattr+1) *
393                                         sizeof(struct nlattr *), GFP_KERNEL);
394                 if (family->attrbuf == NULL) {
395                         err = -ENOMEM;
396                         goto errout_locked;
397                 }
398         } else
399                 family->attrbuf = NULL;
400
401         list_add_tail(&family->family_list, genl_family_chain(family->id));
402         genl_unlock();
403
404         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);
405
406         return 0;
407
408 errout_locked:
409         genl_unlock();
410 errout:
411         return err;
412 }
413
414 /**
415  * genl_register_family_with_ops - register a generic netlink family
416  * @family: generic netlink family
417  * @ops: operations to be registered
418  * @n_ops: number of elements to register
419  *
420  * Registers the specified family and operations from the specified table.
421  * Only one family may be registered with the same family name or identifier.
422  *
423  * The family id may equal GENL_ID_GENERATE causing an unique id to
424  * be automatically generated and assigned.
425  *
426  * Either a doit or dumpit callback must be specified for every registered
427  * operation or the function will fail. Only one operation structure per
428  * command identifier may be registered.
429  *
430  * See include/net/genetlink.h for more documenation on the operations
431  * structure.
432  *
433  * This is equivalent to calling genl_register_family() followed by
434  * genl_register_ops() for every operation entry in the table taking
435  * care to unregister the family on error path.
436  *
437  * Return 0 on success or a negative error code.
438  */
439 int genl_register_family_with_ops(struct genl_family *family,
440         struct genl_ops *ops, size_t n_ops)
441 {
442         int err, i;
443
444         err = genl_register_family(family);
445         if (err)
446                 return err;
447
448         for (i = 0; i < n_ops; ++i, ++ops) {
449                 err = genl_register_ops(family, ops);
450                 if (err)
451                         goto err_out;
452         }
453         return 0;
454 err_out:
455         genl_unregister_family(family);
456         return err;
457 }
458 EXPORT_SYMBOL(genl_register_family_with_ops);
459
460 /**
461  * genl_unregister_family - unregister generic netlink family
462  * @family: generic netlink family
463  *
464  * Unregisters the specified family.
465  *
466  * Returns 0 on success or a negative error code.
467  */
468 int genl_unregister_family(struct genl_family *family)
469 {
470         struct genl_family *rc;
471
472         genl_lock();
473
474         genl_unregister_mc_groups(family);
475
476         list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
477                 if (family->id != rc->id || strcmp(rc->name, family->name))
478                         continue;
479
480                 list_del(&rc->family_list);
481                 INIT_LIST_HEAD(&family->ops_list);
482                 genl_unlock();
483
484                 kfree(family->attrbuf);
485                 genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
486                 return 0;
487         }
488
489         genl_unlock();
490
491         return -ENOENT;
492 }
493
494 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
495 {
496         struct genl_ops *ops;
497         struct genl_family *family;
498         struct net *net = sock_net(skb->sk);
499         struct genl_info info;
500         struct genlmsghdr *hdr = nlmsg_data(nlh);
501         int hdrlen, err;
502
503         family = genl_family_find_byid(nlh->nlmsg_type);
504         if (family == NULL)
505                 return -ENOENT;
506
507         /* this family doesn't exist in this netns */
508         if (!family->netnsok && !net_eq(net, &init_net))
509                 return -ENOENT;
510
511         hdrlen = GENL_HDRLEN + family->hdrsize;
512         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
513                 return -EINVAL;
514
515         ops = genl_get_cmd(hdr->cmd, family);
516         if (ops == NULL)
517                 return -EOPNOTSUPP;
518
519         if ((ops->flags & GENL_ADMIN_PERM) &&
520             security_netlink_recv(skb, CAP_NET_ADMIN))
521                 return -EPERM;
522
523         if (nlh->nlmsg_flags & NLM_F_DUMP) {
524                 if (ops->dumpit == NULL)
525                         return -EOPNOTSUPP;
526
527                 genl_unlock();
528                 err = netlink_dump_start(net->genl_sock, skb, nlh,
529                                          ops->dumpit, ops->done);
530                 genl_lock();
531                 return err;
532         }
533
534         if (ops->doit == NULL)
535                 return -EOPNOTSUPP;
536
537         if (family->attrbuf) {
538                 err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr,
539                                   ops->policy);
540                 if (err < 0)
541                         return err;
542         }
543
544         info.snd_seq = nlh->nlmsg_seq;
545         info.snd_pid = NETLINK_CB(skb).pid;
546         info.nlhdr = nlh;
547         info.genlhdr = nlmsg_data(nlh);
548         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
549         info.attrs = family->attrbuf;
550         genl_info_net_set(&info, net);
551
552         return ops->doit(skb, &info);
553 }
554
555 static void genl_rcv(struct sk_buff *skb)
556 {
557         genl_lock();
558         netlink_rcv_skb(skb, &genl_rcv_msg);
559         genl_unlock();
560 }
561
562 /**************************************************************************
563  * Controller
564  **************************************************************************/
565
566 static struct genl_family genl_ctrl = {
567         .id = GENL_ID_CTRL,
568         .name = "nlctrl",
569         .version = 0x2,
570         .maxattr = CTRL_ATTR_MAX,
571         .netnsok = true,
572 };
573
574 static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
575                           u32 flags, struct sk_buff *skb, u8 cmd)
576 {
577         void *hdr;
578
579         hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
580         if (hdr == NULL)
581                 return -1;
582
583         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, family->name);
584         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, family->id);
585         NLA_PUT_U32(skb, CTRL_ATTR_VERSION, family->version);
586         NLA_PUT_U32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize);
587         NLA_PUT_U32(skb, CTRL_ATTR_MAXATTR, family->maxattr);
588
589         if (!list_empty(&family->ops_list)) {
590                 struct nlattr *nla_ops;
591                 struct genl_ops *ops;
592                 int idx = 1;
593
594                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
595                 if (nla_ops == NULL)
596                         goto nla_put_failure;
597
598                 list_for_each_entry(ops, &family->ops_list, ops_list) {
599                         struct nlattr *nest;
600
601                         nest = nla_nest_start(skb, idx++);
602                         if (nest == NULL)
603                                 goto nla_put_failure;
604
605                         NLA_PUT_U32(skb, CTRL_ATTR_OP_ID, ops->cmd);
606                         NLA_PUT_U32(skb, CTRL_ATTR_OP_FLAGS, ops->flags);
607
608                         nla_nest_end(skb, nest);
609                 }
610
611                 nla_nest_end(skb, nla_ops);
612         }
613
614         if (!list_empty(&family->mcast_groups)) {
615                 struct genl_multicast_group *grp;
616                 struct nlattr *nla_grps;
617                 int idx = 1;
618
619                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
620                 if (nla_grps == NULL)
621                         goto nla_put_failure;
622
623                 list_for_each_entry(grp, &family->mcast_groups, list) {
624                         struct nlattr *nest;
625
626                         nest = nla_nest_start(skb, idx++);
627                         if (nest == NULL)
628                                 goto nla_put_failure;
629
630                         NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
631                         NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
632                                        grp->name);
633
634                         nla_nest_end(skb, nest);
635                 }
636                 nla_nest_end(skb, nla_grps);
637         }
638
639         return genlmsg_end(skb, hdr);
640
641 nla_put_failure:
642         genlmsg_cancel(skb, hdr);
643         return -EMSGSIZE;
644 }
645
646 static int ctrl_fill_mcgrp_info(struct genl_multicast_group *grp, u32 pid,
647                                 u32 seq, u32 flags, struct sk_buff *skb,
648                                 u8 cmd)
649 {
650         void *hdr;
651         struct nlattr *nla_grps;
652         struct nlattr *nest;
653
654         hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
655         if (hdr == NULL)
656                 return -1;
657
658         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, grp->family->name);
659         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, grp->family->id);
660
661         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
662         if (nla_grps == NULL)
663                 goto nla_put_failure;
664
665         nest = nla_nest_start(skb, 1);
666         if (nest == NULL)
667                 goto nla_put_failure;
668
669         NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
670         NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
671                        grp->name);
672
673         nla_nest_end(skb, nest);
674         nla_nest_end(skb, nla_grps);
675
676         return genlmsg_end(skb, hdr);
677
678 nla_put_failure:
679         genlmsg_cancel(skb, hdr);
680         return -EMSGSIZE;
681 }
682
683 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
684 {
685
686         int i, n = 0;
687         struct genl_family *rt;
688         struct net *net = sock_net(skb->sk);
689         int chains_to_skip = cb->args[0];
690         int fams_to_skip = cb->args[1];
691
692         for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
693                 if (i < chains_to_skip)
694                         continue;
695                 n = 0;
696                 list_for_each_entry(rt, genl_family_chain(i), family_list) {
697                         if (!rt->netnsok && !net_eq(net, &init_net))
698                                 continue;
699                         if (++n < fams_to_skip)
700                                 continue;
701                         if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).pid,
702                                            cb->nlh->nlmsg_seq, NLM_F_MULTI,
703                                            skb, CTRL_CMD_NEWFAMILY) < 0)
704                                 goto errout;
705                 }
706
707                 fams_to_skip = 0;
708         }
709
710 errout:
711         cb->args[0] = i;
712         cb->args[1] = n;
713
714         return skb->len;
715 }
716
717 static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
718                                              u32 pid, int seq, u8 cmd)
719 {
720         struct sk_buff *skb;
721         int err;
722
723         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
724         if (skb == NULL)
725                 return ERR_PTR(-ENOBUFS);
726
727         err = ctrl_fill_info(family, pid, seq, 0, skb, cmd);
728         if (err < 0) {
729                 nlmsg_free(skb);
730                 return ERR_PTR(err);
731         }
732
733         return skb;
734 }
735
736 static struct sk_buff *ctrl_build_mcgrp_msg(struct genl_multicast_group *grp,
737                                             u32 pid, int seq, u8 cmd)
738 {
739         struct sk_buff *skb;
740         int err;
741
742         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
743         if (skb == NULL)
744                 return ERR_PTR(-ENOBUFS);
745
746         err = ctrl_fill_mcgrp_info(grp, pid, seq, 0, skb, cmd);
747         if (err < 0) {
748                 nlmsg_free(skb);
749                 return ERR_PTR(err);
750         }
751
752         return skb;
753 }
754
755 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
756         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
757         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
758                                     .len = GENL_NAMSIZ - 1 },
759 };
760
761 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
762 {
763         struct sk_buff *msg;
764         struct genl_family *res = NULL;
765         int err = -EINVAL;
766
767         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
768                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
769                 res = genl_family_find_byid(id);
770                 err = -ENOENT;
771         }
772
773         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
774                 char *name;
775
776                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
777                 res = genl_family_find_byname(name);
778                 err = -ENOENT;
779         }
780
781         if (res == NULL)
782                 return err;
783
784         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
785                 /* family doesn't exist here */
786                 return -ENOENT;
787         }
788
789         msg = ctrl_build_family_msg(res, info->snd_pid, info->snd_seq,
790                                     CTRL_CMD_NEWFAMILY);
791         if (IS_ERR(msg))
792                 return PTR_ERR(msg);
793
794         return genlmsg_reply(msg, info);
795 }
796
797 static int genl_ctrl_event(int event, void *data)
798 {
799         struct sk_buff *msg;
800         struct genl_family *family;
801         struct genl_multicast_group *grp;
802
803         /* genl is still initialising */
804         if (!init_net.genl_sock)
805                 return 0;
806
807         switch (event) {
808         case CTRL_CMD_NEWFAMILY:
809         case CTRL_CMD_DELFAMILY:
810                 family = data;
811                 msg = ctrl_build_family_msg(family, 0, 0, event);
812                 break;
813         case CTRL_CMD_NEWMCAST_GRP:
814         case CTRL_CMD_DELMCAST_GRP:
815                 grp = data;
816                 family = grp->family;
817                 msg = ctrl_build_mcgrp_msg(data, 0, 0, event);
818                 break;
819         default:
820                 return -EINVAL;
821         }
822
823         if (IS_ERR(msg))
824                 return PTR_ERR(msg);
825
826         if (!family->netnsok) {
827                 genlmsg_multicast_netns(&init_net, msg, 0,
828                                         GENL_ID_CTRL, GFP_KERNEL);
829         } else {
830                 rcu_read_lock();
831                 genlmsg_multicast_allns(msg, 0, GENL_ID_CTRL, GFP_ATOMIC);
832                 rcu_read_unlock();
833         }
834
835         return 0;
836 }
837
838 static struct genl_ops genl_ctrl_ops = {
839         .cmd            = CTRL_CMD_GETFAMILY,
840         .doit           = ctrl_getfamily,
841         .dumpit         = ctrl_dumpfamily,
842         .policy         = ctrl_policy,
843 };
844
845 static struct genl_multicast_group notify_grp = {
846         .name           = "notify",
847 };
848
849 static int __net_init genl_pernet_init(struct net *net)
850 {
851         /* we'll bump the group number right afterwards */
852         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, 0,
853                                                genl_rcv, &genl_mutex,
854                                                THIS_MODULE);
855
856         if (!net->genl_sock && net_eq(net, &init_net))
857                 panic("GENL: Cannot initialize generic netlink\n");
858
859         if (!net->genl_sock)
860                 return -ENOMEM;
861
862         return 0;
863 }
864
865 static void __net_exit genl_pernet_exit(struct net *net)
866 {
867         netlink_kernel_release(net->genl_sock);
868         net->genl_sock = NULL;
869 }
870
871 static struct pernet_operations genl_pernet_ops = {
872         .init = genl_pernet_init,
873         .exit = genl_pernet_exit,
874 };
875
876 static int __init genl_init(void)
877 {
878         int i, err;
879
880         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
881                 INIT_LIST_HEAD(&family_ht[i]);
882
883         err = genl_register_family(&genl_ctrl);
884         if (err < 0)
885                 goto problem;
886
887         err = genl_register_ops(&genl_ctrl, &genl_ctrl_ops);
888         if (err < 0)
889                 goto problem;
890
891         netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);
892
893         err = register_pernet_subsys(&genl_pernet_ops);
894         if (err)
895                 goto problem;
896
897         err = genl_register_mc_group(&genl_ctrl, &notify_grp);
898         if (err < 0)
899                 goto problem;
900
901         return 0;
902
903 problem:
904         panic("GENL: Cannot register controller: %d\n", err);
905 }
906
907 subsys_initcall(genl_init);
908
909 EXPORT_SYMBOL(genl_register_ops);
910 EXPORT_SYMBOL(genl_unregister_ops);
911 EXPORT_SYMBOL(genl_register_family);
912 EXPORT_SYMBOL(genl_unregister_family);
913
914 static int genlmsg_mcast(struct sk_buff *skb, u32 pid, unsigned long group,
915                          gfp_t flags)
916 {
917         struct sk_buff *tmp;
918         struct net *net, *prev = NULL;
919         int err;
920
921         for_each_net_rcu(net) {
922                 if (prev) {
923                         tmp = skb_clone(skb, flags);
924                         if (!tmp) {
925                                 err = -ENOMEM;
926                                 goto error;
927                         }
928                         err = nlmsg_multicast(prev->genl_sock, tmp,
929                                               pid, group, flags);
930                         if (err)
931                                 goto error;
932                 }
933
934                 prev = net;
935         }
936
937         return nlmsg_multicast(prev->genl_sock, skb, pid, group, flags);
938  error:
939         kfree_skb(skb);
940         return err;
941 }
942
943 int genlmsg_multicast_allns(struct sk_buff *skb, u32 pid, unsigned int group,
944                             gfp_t flags)
945 {
946         return genlmsg_mcast(skb, pid, group, flags);
947 }
948 EXPORT_SYMBOL(genlmsg_multicast_allns);