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Linux/net/netlink/genetlink.c

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  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/slab.h>
 12 #include <linux/errno.h>
 13 #include <linux/types.h>
 14 #include <linux/socket.h>
 15 #include <linux/string.h>
 16 #include <linux/skbuff.h>
 17 #include <linux/mutex.h>
 18 #include <linux/bitmap.h>
 19 #include <linux/rwsem.h>
 20 #include <net/sock.h>
 21 #include <net/genetlink.h>
 22 
 23 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
 24 static DECLARE_RWSEM(cb_lock);
 25 
 26 void genl_lock(void)
 27 {
 28         mutex_lock(&genl_mutex);
 29 }
 30 EXPORT_SYMBOL(genl_lock);
 31 
 32 void genl_unlock(void)
 33 {
 34         mutex_unlock(&genl_mutex);
 35 }
 36 EXPORT_SYMBOL(genl_unlock);
 37 
 38 #ifdef CONFIG_LOCKDEP
 39 int lockdep_genl_is_held(void)
 40 {
 41         return lockdep_is_held(&genl_mutex);
 42 }
 43 EXPORT_SYMBOL(lockdep_genl_is_held);
 44 #endif
 45 
 46 static void genl_lock_all(void)
 47 {
 48         down_write(&cb_lock);
 49         genl_lock();
 50 }
 51 
 52 static void genl_unlock_all(void)
 53 {
 54         genl_unlock();
 55         up_write(&cb_lock);
 56 }
 57 
 58 #define GENL_FAM_TAB_SIZE       16
 59 #define GENL_FAM_TAB_MASK       (GENL_FAM_TAB_SIZE - 1)
 60 
 61 static struct list_head family_ht[GENL_FAM_TAB_SIZE];
 62 /*
 63  * Bitmap of multicast groups that are currently in use.
 64  *
 65  * To avoid an allocation at boot of just one unsigned long,
 66  * declare it global instead.
 67  * Bit 0 is marked as already used since group 0 is invalid.
 68  * Bit 1 is marked as already used since the drop-monitor code
 69  * abuses the API and thinks it can statically use group 1.
 70  * That group will typically conflict with other groups that
 71  * any proper users use.
 72  * Bit 16 is marked as used since it's used for generic netlink
 73  * and the code no longer marks pre-reserved IDs as used.
 74  * Bit 17 is marked as already used since the VFS quota code
 75  * also abused this API and relied on family == group ID, we
 76  * cater to that by giving it a static family and group ID.
 77  * Bit 18 is marked as already used since the PMCRAID driver
 78  * did the same thing as the VFS quota code (maybe copied?)
 79  */
 80 static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) |
 81                                       BIT(GENL_ID_VFS_DQUOT) |
 82                                       BIT(GENL_ID_PMCRAID);
 83 static unsigned long *mc_groups = &mc_group_start;
 84 static unsigned long mc_groups_longs = 1;
 85 
 86 static int genl_ctrl_event(int event, struct genl_family *family,
 87                            const struct genl_multicast_group *grp,
 88                            int grp_id);
 89 
 90 static inline unsigned int genl_family_hash(unsigned int id)
 91 {
 92         return id & GENL_FAM_TAB_MASK;
 93 }
 94 
 95 static inline struct list_head *genl_family_chain(unsigned int id)
 96 {
 97         return &family_ht[genl_family_hash(id)];
 98 }
 99 
100 static struct genl_family *genl_family_find_byid(unsigned int id)
101 {
102         struct genl_family *f;
103 
104         list_for_each_entry(f, genl_family_chain(id), family_list)
105                 if (f->id == id)
106                         return f;
107 
108         return NULL;
109 }
110 
111 static struct genl_family *genl_family_find_byname(char *name)
112 {
113         struct genl_family *f;
114         int i;
115 
116         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
117                 list_for_each_entry(f, genl_family_chain(i), family_list)
118                         if (strcmp(f->name, name) == 0)
119                                 return f;
120 
121         return NULL;
122 }
123 
124 static const struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
125 {
126         int i;
127 
128         for (i = 0; i < family->n_ops; i++)
129                 if (family->ops[i].cmd == cmd)
130                         return &family->ops[i];
131 
132         return NULL;
133 }
134 
135 /* Of course we are going to have problems once we hit
136  * 2^16 alive types, but that can only happen by year 2K
137 */
138 static u16 genl_generate_id(void)
139 {
140         static u16 id_gen_idx = GENL_MIN_ID;
141         int i;
142 
143         for (i = 0; i <= GENL_MAX_ID - GENL_MIN_ID; i++) {
144                 if (id_gen_idx != GENL_ID_VFS_DQUOT &&
145                     id_gen_idx != GENL_ID_PMCRAID &&
146                     !genl_family_find_byid(id_gen_idx))
147                         return id_gen_idx;
148                 if (++id_gen_idx > GENL_MAX_ID)
149                         id_gen_idx = GENL_MIN_ID;
150         }
151 
152         return 0;
153 }
154 
155 static int genl_allocate_reserve_groups(int n_groups, int *first_id)
156 {
157         unsigned long *new_groups;
158         int start = 0;
159         int i;
160         int id;
161         bool fits;
162 
163         do {
164                 if (start == 0)
165                         id = find_first_zero_bit(mc_groups,
166                                                  mc_groups_longs *
167                                                  BITS_PER_LONG);
168                 else
169                         id = find_next_zero_bit(mc_groups,
170                                                 mc_groups_longs * BITS_PER_LONG,
171                                                 start);
172 
173                 fits = true;
174                 for (i = id;
175                      i < min_t(int, id + n_groups,
176                                mc_groups_longs * BITS_PER_LONG);
177                      i++) {
178                         if (test_bit(i, mc_groups)) {
179                                 start = i;
180                                 fits = false;
181                                 break;
182                         }
183                 }
184 
185                 if (id >= mc_groups_longs * BITS_PER_LONG) {
186                         unsigned long new_longs = mc_groups_longs +
187                                                   BITS_TO_LONGS(n_groups);
188                         size_t nlen = new_longs * sizeof(unsigned long);
189 
190                         if (mc_groups == &mc_group_start) {
191                                 new_groups = kzalloc(nlen, GFP_KERNEL);
192                                 if (!new_groups)
193                                         return -ENOMEM;
194                                 mc_groups = new_groups;
195                                 *mc_groups = mc_group_start;
196                         } else {
197                                 new_groups = krealloc(mc_groups, nlen,
198                                                       GFP_KERNEL);
199                                 if (!new_groups)
200                                         return -ENOMEM;
201                                 mc_groups = new_groups;
202                                 for (i = 0; i < BITS_TO_LONGS(n_groups); i++)
203                                         mc_groups[mc_groups_longs + i] = 0;
204                         }
205                         mc_groups_longs = new_longs;
206                 }
207         } while (!fits);
208 
209         for (i = id; i < id + n_groups; i++)
210                 set_bit(i, mc_groups);
211         *first_id = id;
212         return 0;
213 }
214 
215 static struct genl_family genl_ctrl;
216 
217 static int genl_validate_assign_mc_groups(struct genl_family *family)
218 {
219         int first_id;
220         int n_groups = family->n_mcgrps;
221         int err = 0, i;
222         bool groups_allocated = false;
223 
224         if (!n_groups)
225                 return 0;
226 
227         for (i = 0; i < n_groups; i++) {
228                 const struct genl_multicast_group *grp = &family->mcgrps[i];
229 
230                 if (WARN_ON(grp->name[0] == '\0'))
231                         return -EINVAL;
232                 if (WARN_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL))
233                         return -EINVAL;
234         }
235 
236         /* special-case our own group and hacks */
237         if (family == &genl_ctrl) {
238                 first_id = GENL_ID_CTRL;
239                 BUG_ON(n_groups != 1);
240         } else if (strcmp(family->name, "NET_DM") == 0) {
241                 first_id = 1;
242                 BUG_ON(n_groups != 1);
243         } else if (family->id == GENL_ID_VFS_DQUOT) {
244                 first_id = GENL_ID_VFS_DQUOT;
245                 BUG_ON(n_groups != 1);
246         } else if (family->id == GENL_ID_PMCRAID) {
247                 first_id = GENL_ID_PMCRAID;
248                 BUG_ON(n_groups != 1);
249         } else {
250                 groups_allocated = true;
251                 err = genl_allocate_reserve_groups(n_groups, &first_id);
252                 if (err)
253                         return err;
254         }
255 
256         family->mcgrp_offset = first_id;
257 
258         /* if still initializing, can't and don't need to to realloc bitmaps */
259         if (!init_net.genl_sock)
260                 return 0;
261 
262         if (family->netnsok) {
263                 struct net *net;
264 
265                 netlink_table_grab();
266                 rcu_read_lock();
267                 for_each_net_rcu(net) {
268                         err = __netlink_change_ngroups(net->genl_sock,
269                                         mc_groups_longs * BITS_PER_LONG);
270                         if (err) {
271                                 /*
272                                  * No need to roll back, can only fail if
273                                  * memory allocation fails and then the
274                                  * number of _possible_ groups has been
275                                  * increased on some sockets which is ok.
276                                  */
277                                 break;
278                         }
279                 }
280                 rcu_read_unlock();
281                 netlink_table_ungrab();
282         } else {
283                 err = netlink_change_ngroups(init_net.genl_sock,
284                                              mc_groups_longs * BITS_PER_LONG);
285         }
286 
287         if (groups_allocated && err) {
288                 for (i = 0; i < family->n_mcgrps; i++)
289                         clear_bit(family->mcgrp_offset + i, mc_groups);
290         }
291 
292         return err;
293 }
294 
295 static void genl_unregister_mc_groups(struct genl_family *family)
296 {
297         struct net *net;
298         int i;
299 
300         netlink_table_grab();
301         rcu_read_lock();
302         for_each_net_rcu(net) {
303                 for (i = 0; i < family->n_mcgrps; i++)
304                         __netlink_clear_multicast_users(
305                                 net->genl_sock, family->mcgrp_offset + i);
306         }
307         rcu_read_unlock();
308         netlink_table_ungrab();
309 
310         for (i = 0; i < family->n_mcgrps; i++) {
311                 int grp_id = family->mcgrp_offset + i;
312 
313                 if (grp_id != 1)
314                         clear_bit(grp_id, mc_groups);
315                 genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, family,
316                                 &family->mcgrps[i], grp_id);
317         }
318 }
319 
320 static int genl_validate_ops(const struct genl_family *family)
321 {
322         const struct genl_ops *ops = family->ops;
323         unsigned int n_ops = family->n_ops;
324         int i, j;
325 
326         if (WARN_ON(n_ops && !ops))
327                 return -EINVAL;
328 
329         if (!n_ops)
330                 return 0;
331 
332         for (i = 0; i < n_ops; i++) {
333                 if (ops[i].dumpit == NULL && ops[i].doit == NULL)
334                         return -EINVAL;
335                 for (j = i + 1; j < n_ops; j++)
336                         if (ops[i].cmd == ops[j].cmd)
337                                 return -EINVAL;
338         }
339 
340         return 0;
341 }
342 
343 /**
344  * __genl_register_family - register a generic netlink family
345  * @family: generic netlink family
346  *
347  * Registers the specified family after validating it first. Only one
348  * family may be registered with the same family name or identifier.
349  * The family id may equal GENL_ID_GENERATE causing an unique id to
350  * be automatically generated and assigned.
351  *
352  * The family's ops array must already be assigned, you can use the
353  * genl_register_family_with_ops() helper function.
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, i;
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         err = genl_validate_ops(family);
368         if (err)
369                 return err;
370 
371         genl_lock_all();
372 
373         if (genl_family_find_byname(family->name)) {
374                 err = -EEXIST;
375                 goto errout_locked;
376         }
377 
378         if (family->id == GENL_ID_GENERATE) {
379                 u16 newid = genl_generate_id();
380 
381                 if (!newid) {
382                         err = -ENOMEM;
383                         goto errout_locked;
384                 }
385 
386                 family->id = newid;
387         } else if (genl_family_find_byid(family->id)) {
388                 err = -EEXIST;
389                 goto errout_locked;
390         }
391 
392         if (family->maxattr && !family->parallel_ops) {
393                 family->attrbuf = kmalloc((family->maxattr+1) *
394                                         sizeof(struct nlattr *), GFP_KERNEL);
395                 if (family->attrbuf == NULL) {
396                         err = -ENOMEM;
397                         goto errout_locked;
398                 }
399         } else
400                 family->attrbuf = NULL;
401 
402         err = genl_validate_assign_mc_groups(family);
403         if (err)
404                 goto errout_locked;
405 
406         list_add_tail(&family->family_list, genl_family_chain(family->id));
407         genl_unlock_all();
408 
409         /* send all events */
410         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0);
411         for (i = 0; i < family->n_mcgrps; i++)
412                 genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family,
413                                 &family->mcgrps[i], family->mcgrp_offset + i);
414 
415         return 0;
416 
417 errout_locked:
418         genl_unlock_all();
419 errout:
420         return err;
421 }
422 EXPORT_SYMBOL(__genl_register_family);
423 
424 /**
425  * genl_unregister_family - unregister generic netlink family
426  * @family: generic netlink family
427  *
428  * Unregisters the specified family.
429  *
430  * Returns 0 on success or a negative error code.
431  */
432 int genl_unregister_family(struct genl_family *family)
433 {
434         struct genl_family *rc;
435 
436         genl_lock_all();
437 
438         genl_unregister_mc_groups(family);
439 
440         list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
441                 if (family->id != rc->id || strcmp(rc->name, family->name))
442                         continue;
443 
444                 list_del(&rc->family_list);
445                 family->n_ops = 0;
446                 genl_unlock_all();
447 
448                 kfree(family->attrbuf);
449                 genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
450                 return 0;
451         }
452 
453         genl_unlock_all();
454 
455         return -ENOENT;
456 }
457 EXPORT_SYMBOL(genl_unregister_family);
458 
459 /**
460  * genlmsg_new_unicast - Allocate generic netlink message for unicast
461  * @payload: size of the message payload
462  * @info: information on destination
463  * @flags: the type of memory to allocate
464  *
465  * Allocates a new sk_buff large enough to cover the specified payload
466  * plus required Netlink headers. Will check receiving socket for
467  * memory mapped i/o capability and use it if enabled. Will fall back
468  * to non-mapped skb if message size exceeds the frame size of the ring.
469  */
470 struct sk_buff *genlmsg_new_unicast(size_t payload, struct genl_info *info,
471                                     gfp_t flags)
472 {
473         size_t len = nlmsg_total_size(genlmsg_total_size(payload));
474 
475         return netlink_alloc_skb(info->dst_sk, len, info->snd_portid, flags);
476 }
477 EXPORT_SYMBOL_GPL(genlmsg_new_unicast);
478 
479 /**
480  * genlmsg_put - Add generic netlink header to netlink message
481  * @skb: socket buffer holding the message
482  * @portid: netlink portid the message is addressed to
483  * @seq: sequence number (usually the one of the sender)
484  * @family: generic netlink family
485  * @flags: netlink message flags
486  * @cmd: generic netlink command
487  *
488  * Returns pointer to user specific header
489  */
490 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
491                                 struct genl_family *family, int flags, u8 cmd)
492 {
493         struct nlmsghdr *nlh;
494         struct genlmsghdr *hdr;
495 
496         nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
497                         family->hdrsize, flags);
498         if (nlh == NULL)
499                 return NULL;
500 
501         hdr = nlmsg_data(nlh);
502         hdr->cmd = cmd;
503         hdr->version = family->version;
504         hdr->reserved = 0;
505 
506         return (char *) hdr + GENL_HDRLEN;
507 }
508 EXPORT_SYMBOL(genlmsg_put);
509 
510 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
511 {
512         /* our ops are always const - netlink API doesn't propagate that */
513         const struct genl_ops *ops = cb->data;
514         int rc;
515 
516         genl_lock();
517         rc = ops->dumpit(skb, cb);
518         genl_unlock();
519         return rc;
520 }
521 
522 static int genl_lock_done(struct netlink_callback *cb)
523 {
524         /* our ops are always const - netlink API doesn't propagate that */
525         const struct genl_ops *ops = cb->data;
526         int rc = 0;
527 
528         if (ops->done) {
529                 genl_lock();
530                 rc = ops->done(cb);
531                 genl_unlock();
532         }
533         return rc;
534 }
535 
536 static int genl_family_rcv_msg(struct genl_family *family,
537                                struct sk_buff *skb,
538                                struct nlmsghdr *nlh)
539 {
540         const struct genl_ops *ops;
541         struct net *net = sock_net(skb->sk);
542         struct genl_info info;
543         struct genlmsghdr *hdr = nlmsg_data(nlh);
544         struct nlattr **attrbuf;
545         int hdrlen, err;
546 
547         /* this family doesn't exist in this netns */
548         if (!family->netnsok && !net_eq(net, &init_net))
549                 return -ENOENT;
550 
551         hdrlen = GENL_HDRLEN + family->hdrsize;
552         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
553                 return -EINVAL;
554 
555         ops = genl_get_cmd(hdr->cmd, family);
556         if (ops == NULL)
557                 return -EOPNOTSUPP;
558 
559         if ((ops->flags & GENL_ADMIN_PERM) &&
560             !netlink_capable(skb, CAP_NET_ADMIN))
561                 return -EPERM;
562 
563         if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
564                 int rc;
565 
566                 if (ops->dumpit == NULL)
567                         return -EOPNOTSUPP;
568 
569                 if (!family->parallel_ops) {
570                         struct netlink_dump_control c = {
571                                 .module = family->module,
572                                 /* we have const, but the netlink API doesn't */
573                                 .data = (void *)ops,
574                                 .dump = genl_lock_dumpit,
575                                 .done = genl_lock_done,
576                         };
577 
578                         genl_unlock();
579                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
580                         genl_lock();
581 
582                 } else {
583                         struct netlink_dump_control c = {
584                                 .module = family->module,
585                                 .dump = ops->dumpit,
586                                 .done = ops->done,
587                         };
588 
589                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
590                 }
591 
592                 return rc;
593         }
594 
595         if (ops->doit == NULL)
596                 return -EOPNOTSUPP;
597 
598         if (family->maxattr && family->parallel_ops) {
599                 attrbuf = kmalloc((family->maxattr+1) *
600                                         sizeof(struct nlattr *), GFP_KERNEL);
601                 if (attrbuf == NULL)
602                         return -ENOMEM;
603         } else
604                 attrbuf = family->attrbuf;
605 
606         if (attrbuf) {
607                 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
608                                   ops->policy);
609                 if (err < 0)
610                         goto out;
611         }
612 
613         info.snd_seq = nlh->nlmsg_seq;
614         info.snd_portid = NETLINK_CB(skb).portid;
615         info.nlhdr = nlh;
616         info.genlhdr = nlmsg_data(nlh);
617         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
618         info.attrs = attrbuf;
619         info.dst_sk = skb->sk;
620         genl_info_net_set(&info, net);
621         memset(&info.user_ptr, 0, sizeof(info.user_ptr));
622 
623         if (family->pre_doit) {
624                 err = family->pre_doit(ops, skb, &info);
625                 if (err)
626                         goto out;
627         }
628 
629         err = ops->doit(skb, &info);
630 
631         if (family->post_doit)
632                 family->post_doit(ops, skb, &info);
633 
634 out:
635         if (family->parallel_ops)
636                 kfree(attrbuf);
637 
638         return err;
639 }
640 
641 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
642 {
643         struct genl_family *family;
644         int err;
645 
646         family = genl_family_find_byid(nlh->nlmsg_type);
647         if (family == NULL)
648                 return -ENOENT;
649 
650         if (!family->parallel_ops)
651                 genl_lock();
652 
653         err = genl_family_rcv_msg(family, skb, nlh);
654 
655         if (!family->parallel_ops)
656                 genl_unlock();
657 
658         return err;
659 }
660 
661 static void genl_rcv(struct sk_buff *skb)
662 {
663         down_read(&cb_lock);
664         netlink_rcv_skb(skb, &genl_rcv_msg);
665         up_read(&cb_lock);
666 }
667 
668 /**************************************************************************
669  * Controller
670  **************************************************************************/
671 
672 static struct genl_family genl_ctrl = {
673         .id = GENL_ID_CTRL,
674         .name = "nlctrl",
675         .version = 0x2,
676         .maxattr = CTRL_ATTR_MAX,
677         .netnsok = true,
678 };
679 
680 static int ctrl_fill_info(struct genl_family *family, u32 portid, u32 seq,
681                           u32 flags, struct sk_buff *skb, u8 cmd)
682 {
683         void *hdr;
684 
685         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
686         if (hdr == NULL)
687                 return -1;
688 
689         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
690             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
691             nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
692             nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
693             nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
694                 goto nla_put_failure;
695 
696         if (family->n_ops) {
697                 struct nlattr *nla_ops;
698                 int i;
699 
700                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
701                 if (nla_ops == NULL)
702                         goto nla_put_failure;
703 
704                 for (i = 0; i < family->n_ops; i++) {
705                         struct nlattr *nest;
706                         const struct genl_ops *ops = &family->ops[i];
707                         u32 op_flags = ops->flags;
708 
709                         if (ops->dumpit)
710                                 op_flags |= GENL_CMD_CAP_DUMP;
711                         if (ops->doit)
712                                 op_flags |= GENL_CMD_CAP_DO;
713                         if (ops->policy)
714                                 op_flags |= GENL_CMD_CAP_HASPOL;
715 
716                         nest = nla_nest_start(skb, i + 1);
717                         if (nest == NULL)
718                                 goto nla_put_failure;
719 
720                         if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
721                             nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
722                                 goto nla_put_failure;
723 
724                         nla_nest_end(skb, nest);
725                 }
726 
727                 nla_nest_end(skb, nla_ops);
728         }
729 
730         if (family->n_mcgrps) {
731                 struct nlattr *nla_grps;
732                 int i;
733 
734                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
735                 if (nla_grps == NULL)
736                         goto nla_put_failure;
737 
738                 for (i = 0; i < family->n_mcgrps; i++) {
739                         struct nlattr *nest;
740                         const struct genl_multicast_group *grp;
741 
742                         grp = &family->mcgrps[i];
743 
744                         nest = nla_nest_start(skb, i + 1);
745                         if (nest == NULL)
746                                 goto nla_put_failure;
747 
748                         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
749                                         family->mcgrp_offset + i) ||
750                             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
751                                            grp->name))
752                                 goto nla_put_failure;
753 
754                         nla_nest_end(skb, nest);
755                 }
756                 nla_nest_end(skb, nla_grps);
757         }
758 
759         return genlmsg_end(skb, hdr);
760 
761 nla_put_failure:
762         genlmsg_cancel(skb, hdr);
763         return -EMSGSIZE;
764 }
765 
766 static int ctrl_fill_mcgrp_info(struct genl_family *family,
767                                 const struct genl_multicast_group *grp,
768                                 int grp_id, u32 portid, u32 seq, u32 flags,
769                                 struct sk_buff *skb, u8 cmd)
770 {
771         void *hdr;
772         struct nlattr *nla_grps;
773         struct nlattr *nest;
774 
775         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
776         if (hdr == NULL)
777                 return -1;
778 
779         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
780             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
781                 goto nla_put_failure;
782 
783         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
784         if (nla_grps == NULL)
785                 goto nla_put_failure;
786 
787         nest = nla_nest_start(skb, 1);
788         if (nest == NULL)
789                 goto nla_put_failure;
790 
791         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
792             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
793                            grp->name))
794                 goto nla_put_failure;
795 
796         nla_nest_end(skb, nest);
797         nla_nest_end(skb, nla_grps);
798 
799         return genlmsg_end(skb, hdr);
800 
801 nla_put_failure:
802         genlmsg_cancel(skb, hdr);
803         return -EMSGSIZE;
804 }
805 
806 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
807 {
808 
809         int i, n = 0;
810         struct genl_family *rt;
811         struct net *net = sock_net(skb->sk);
812         int chains_to_skip = cb->args[0];
813         int fams_to_skip = cb->args[1];
814 
815         for (i = chains_to_skip; i < GENL_FAM_TAB_SIZE; i++) {
816                 n = 0;
817                 list_for_each_entry(rt, genl_family_chain(i), family_list) {
818                         if (!rt->netnsok && !net_eq(net, &init_net))
819                                 continue;
820                         if (++n < fams_to_skip)
821                                 continue;
822                         if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
823                                            cb->nlh->nlmsg_seq, NLM_F_MULTI,
824                                            skb, CTRL_CMD_NEWFAMILY) < 0)
825                                 goto errout;
826                 }
827 
828                 fams_to_skip = 0;
829         }
830 
831 errout:
832         cb->args[0] = i;
833         cb->args[1] = n;
834 
835         return skb->len;
836 }
837 
838 static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
839                                              u32 portid, int seq, u8 cmd)
840 {
841         struct sk_buff *skb;
842         int err;
843 
844         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
845         if (skb == NULL)
846                 return ERR_PTR(-ENOBUFS);
847 
848         err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
849         if (err < 0) {
850                 nlmsg_free(skb);
851                 return ERR_PTR(err);
852         }
853 
854         return skb;
855 }
856 
857 static struct sk_buff *
858 ctrl_build_mcgrp_msg(struct genl_family *family,
859                      const struct genl_multicast_group *grp,
860                      int grp_id, u32 portid, int seq, u8 cmd)
861 {
862         struct sk_buff *skb;
863         int err;
864 
865         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
866         if (skb == NULL)
867                 return ERR_PTR(-ENOBUFS);
868 
869         err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
870                                    seq, 0, skb, cmd);
871         if (err < 0) {
872                 nlmsg_free(skb);
873                 return ERR_PTR(err);
874         }
875 
876         return skb;
877 }
878 
879 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
880         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
881         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
882                                     .len = GENL_NAMSIZ - 1 },
883 };
884 
885 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
886 {
887         struct sk_buff *msg;
888         struct genl_family *res = NULL;
889         int err = -EINVAL;
890 
891         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
892                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
893                 res = genl_family_find_byid(id);
894                 err = -ENOENT;
895         }
896 
897         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
898                 char *name;
899 
900                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
901                 res = genl_family_find_byname(name);
902 #ifdef CONFIG_MODULES
903                 if (res == NULL) {
904                         genl_unlock();
905                         up_read(&cb_lock);
906                         request_module("net-pf-%d-proto-%d-family-%s",
907                                        PF_NETLINK, NETLINK_GENERIC, name);
908                         down_read(&cb_lock);
909                         genl_lock();
910                         res = genl_family_find_byname(name);
911                 }
912 #endif
913                 err = -ENOENT;
914         }
915 
916         if (res == NULL)
917                 return err;
918 
919         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
920                 /* family doesn't exist here */
921                 return -ENOENT;
922         }
923 
924         msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
925                                     CTRL_CMD_NEWFAMILY);
926         if (IS_ERR(msg))
927                 return PTR_ERR(msg);
928 
929         return genlmsg_reply(msg, info);
930 }
931 
932 static int genl_ctrl_event(int event, struct genl_family *family,
933                            const struct genl_multicast_group *grp,
934                            int grp_id)
935 {
936         struct sk_buff *msg;
937 
938         /* genl is still initialising */
939         if (!init_net.genl_sock)
940                 return 0;
941 
942         switch (event) {
943         case CTRL_CMD_NEWFAMILY:
944         case CTRL_CMD_DELFAMILY:
945                 WARN_ON(grp);
946                 msg = ctrl_build_family_msg(family, 0, 0, event);
947                 break;
948         case CTRL_CMD_NEWMCAST_GRP:
949         case CTRL_CMD_DELMCAST_GRP:
950                 BUG_ON(!grp);
951                 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
952                 break;
953         default:
954                 return -EINVAL;
955         }
956 
957         if (IS_ERR(msg))
958                 return PTR_ERR(msg);
959 
960         if (!family->netnsok) {
961                 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
962                                         0, GFP_KERNEL);
963         } else {
964                 rcu_read_lock();
965                 genlmsg_multicast_allns(&genl_ctrl, msg, 0,
966                                         0, GFP_ATOMIC);
967                 rcu_read_unlock();
968         }
969 
970         return 0;
971 }
972 
973 static struct genl_ops genl_ctrl_ops[] = {
974         {
975                 .cmd            = CTRL_CMD_GETFAMILY,
976                 .doit           = ctrl_getfamily,
977                 .dumpit         = ctrl_dumpfamily,
978                 .policy         = ctrl_policy,
979         },
980 };
981 
982 static struct genl_multicast_group genl_ctrl_groups[] = {
983         { .name = "notify", },
984 };
985 
986 static int __net_init genl_pernet_init(struct net *net)
987 {
988         struct netlink_kernel_cfg cfg = {
989                 .input          = genl_rcv,
990                 .flags          = NL_CFG_F_NONROOT_RECV,
991         };
992 
993         /* we'll bump the group number right afterwards */
994         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
995 
996         if (!net->genl_sock && net_eq(net, &init_net))
997                 panic("GENL: Cannot initialize generic netlink\n");
998 
999         if (!net->genl_sock)
1000                 return -ENOMEM;
1001 
1002         return 0;
1003 }
1004 
1005 static void __net_exit genl_pernet_exit(struct net *net)
1006 {
1007         netlink_kernel_release(net->genl_sock);
1008         net->genl_sock = NULL;
1009 }
1010 
1011 static struct pernet_operations genl_pernet_ops = {
1012         .init = genl_pernet_init,
1013         .exit = genl_pernet_exit,
1014 };
1015 
1016 static int __init genl_init(void)
1017 {
1018         int i, err;
1019 
1020         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
1021                 INIT_LIST_HEAD(&family_ht[i]);
1022 
1023         err = genl_register_family_with_ops_groups(&genl_ctrl, genl_ctrl_ops,
1024                                                    genl_ctrl_groups);
1025         if (err < 0)
1026                 goto problem;
1027 
1028         err = register_pernet_subsys(&genl_pernet_ops);
1029         if (err)
1030                 goto problem;
1031 
1032         return 0;
1033 
1034 problem:
1035         panic("GENL: Cannot register controller: %d\n", err);
1036 }
1037 
1038 subsys_initcall(genl_init);
1039 
1040 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
1041                          gfp_t flags)
1042 {
1043         struct sk_buff *tmp;
1044         struct net *net, *prev = NULL;
1045         int err;
1046 
1047         for_each_net_rcu(net) {
1048                 if (prev) {
1049                         tmp = skb_clone(skb, flags);
1050                         if (!tmp) {
1051                                 err = -ENOMEM;
1052                                 goto error;
1053                         }
1054                         err = nlmsg_multicast(prev->genl_sock, tmp,
1055                                               portid, group, flags);
1056                         if (err)
1057                                 goto error;
1058                 }
1059 
1060                 prev = net;
1061         }
1062 
1063         return nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1064  error:
1065         kfree_skb(skb);
1066         return err;
1067 }
1068 
1069 int genlmsg_multicast_allns(struct genl_family *family, struct sk_buff *skb,
1070                             u32 portid, unsigned int group, gfp_t flags)
1071 {
1072         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1073                 return -EINVAL;
1074         group = family->mcgrp_offset + group;
1075         return genlmsg_mcast(skb, portid, group, flags);
1076 }
1077 EXPORT_SYMBOL(genlmsg_multicast_allns);
1078 
1079 void genl_notify(struct genl_family *family,
1080                  struct sk_buff *skb, struct net *net, u32 portid, u32 group,
1081                  struct nlmsghdr *nlh, gfp_t flags)
1082 {
1083         struct sock *sk = net->genl_sock;
1084         int report = 0;
1085 
1086         if (nlh)
1087                 report = nlmsg_report(nlh);
1088 
1089         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1090                 return;
1091         group = family->mcgrp_offset + group;
1092         nlmsg_notify(sk, skb, portid, group, report, flags);
1093 }
1094 EXPORT_SYMBOL(genl_notify);
1095 

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