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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 <linux/idr.h>
21#include <net/sock.h>
22#include <net/genetlink.h>
23
24static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
25static DECLARE_RWSEM(cb_lock);
26
27atomic_t genl_sk_destructing_cnt = ATOMIC_INIT(0);
28DECLARE_WAIT_QUEUE_HEAD(genl_sk_destructing_waitq);
29
30void genl_lock(void)
31{
32 mutex_lock(&genl_mutex);
33}
34EXPORT_SYMBOL(genl_lock);
35
36void genl_unlock(void)
37{
38 mutex_unlock(&genl_mutex);
39}
40EXPORT_SYMBOL(genl_unlock);
41
42#ifdef CONFIG_LOCKDEP
43bool lockdep_genl_is_held(void)
44{
45 return lockdep_is_held(&genl_mutex);
46}
47EXPORT_SYMBOL(lockdep_genl_is_held);
48#endif
49
50static void genl_lock_all(void)
51{
52 down_write(&cb_lock);
53 genl_lock();
54}
55
56static void genl_unlock_all(void)
57{
58 genl_unlock();
59 up_write(&cb_lock);
60}
61
62static DEFINE_IDR(genl_fam_idr);
63
64/*
65 * Bitmap of multicast groups that are currently in use.
66 *
67 * To avoid an allocation at boot of just one unsigned long,
68 * declare it global instead.
69 * Bit 0 is marked as already used since group 0 is invalid.
70 * Bit 1 is marked as already used since the drop-monitor code
71 * abuses the API and thinks it can statically use group 1.
72 * That group will typically conflict with other groups that
73 * any proper users use.
74 * Bit 16 is marked as used since it's used for generic netlink
75 * and the code no longer marks pre-reserved IDs as used.
76 * Bit 17 is marked as already used since the VFS quota code
77 * also abused this API and relied on family == group ID, we
78 * cater to that by giving it a static family and group ID.
79 * Bit 18 is marked as already used since the PMCRAID driver
80 * did the same thing as the VFS quota code (maybe copied?)
81 */
82static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) |
83 BIT(GENL_ID_VFS_DQUOT) |
84 BIT(GENL_ID_PMCRAID);
85static unsigned long *mc_groups = &mc_group_start;
86static unsigned long mc_groups_longs = 1;
87
88static int genl_ctrl_event(int event, const struct genl_family *family,
89 const struct genl_multicast_group *grp,
90 int grp_id);
91
92static const struct genl_family *genl_family_find_byid(unsigned int id)
93{
94 return idr_find(&genl_fam_idr, id);
95}
96
97static const struct genl_family *genl_family_find_byname(char *name)
98{
99 const struct genl_family *family;
100 unsigned int id;
101
102 idr_for_each_entry(&genl_fam_idr, family, id)
103 if (strcmp(family->name, name) == 0)
104 return family;
105
106 return NULL;
107}
108
109static const struct genl_ops *genl_get_cmd(u8 cmd,
110 const struct genl_family *family)
111{
112 int i;
113
114 for (i = 0; i < family->n_ops; i++)
115 if (family->ops[i].cmd == cmd)
116 return &family->ops[i];
117
118 return NULL;
119}
120
121static int genl_allocate_reserve_groups(int n_groups, int *first_id)
122{
123 unsigned long *new_groups;
124 int start = 0;
125 int i;
126 int id;
127 bool fits;
128
129 do {
130 if (start == 0)
131 id = find_first_zero_bit(mc_groups,
132 mc_groups_longs *
133 BITS_PER_LONG);
134 else
135 id = find_next_zero_bit(mc_groups,
136 mc_groups_longs * BITS_PER_LONG,
137 start);
138
139 fits = true;
140 for (i = id;
141 i < min_t(int, id + n_groups,
142 mc_groups_longs * BITS_PER_LONG);
143 i++) {
144 if (test_bit(i, mc_groups)) {
145 start = i;
146 fits = false;
147 break;
148 }
149 }
150
151 if (id + n_groups > mc_groups_longs * BITS_PER_LONG) {
152 unsigned long new_longs = mc_groups_longs +
153 BITS_TO_LONGS(n_groups);
154 size_t nlen = new_longs * sizeof(unsigned long);
155
156 if (mc_groups == &mc_group_start) {
157 new_groups = kzalloc(nlen, GFP_KERNEL);
158 if (!new_groups)
159 return -ENOMEM;
160 mc_groups = new_groups;
161 *mc_groups = mc_group_start;
162 } else {
163 new_groups = krealloc(mc_groups, nlen,
164 GFP_KERNEL);
165 if (!new_groups)
166 return -ENOMEM;
167 mc_groups = new_groups;
168 for (i = 0; i < BITS_TO_LONGS(n_groups); i++)
169 mc_groups[mc_groups_longs + i] = 0;
170 }
171 mc_groups_longs = new_longs;
172 }
173 } while (!fits);
174
175 for (i = id; i < id + n_groups; i++)
176 set_bit(i, mc_groups);
177 *first_id = id;
178 return 0;
179}
180
181static struct genl_family genl_ctrl;
182
183static int genl_validate_assign_mc_groups(struct genl_family *family)
184{
185 int first_id;
186 int n_groups = family->n_mcgrps;
187 int err = 0, i;
188 bool groups_allocated = false;
189
190 if (!n_groups)
191 return 0;
192
193 for (i = 0; i < n_groups; i++) {
194 const struct genl_multicast_group *grp = &family->mcgrps[i];
195
196 if (WARN_ON(grp->name[0] == '\0'))
197 return -EINVAL;
198 if (WARN_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL))
199 return -EINVAL;
200 }
201
202 /* special-case our own group and hacks */
203 if (family == &genl_ctrl) {
204 first_id = GENL_ID_CTRL;
205 BUG_ON(n_groups != 1);
206 } else if (strcmp(family->name, "NET_DM") == 0) {
207 first_id = 1;
208 BUG_ON(n_groups != 1);
209 } else if (family->id == GENL_ID_VFS_DQUOT) {
210 first_id = GENL_ID_VFS_DQUOT;
211 BUG_ON(n_groups != 1);
212 } else if (family->id == GENL_ID_PMCRAID) {
213 first_id = GENL_ID_PMCRAID;
214 BUG_ON(n_groups != 1);
215 } else {
216 groups_allocated = true;
217 err = genl_allocate_reserve_groups(n_groups, &first_id);
218 if (err)
219 return err;
220 }
221
222 family->mcgrp_offset = first_id;
223
224 /* if still initializing, can't and don't need to to realloc bitmaps */
225 if (!init_net.genl_sock)
226 return 0;
227
228 if (family->netnsok) {
229 struct net *net;
230
231 netlink_table_grab();
232 rcu_read_lock();
233 for_each_net_rcu(net) {
234 err = __netlink_change_ngroups(net->genl_sock,
235 mc_groups_longs * BITS_PER_LONG);
236 if (err) {
237 /*
238 * No need to roll back, can only fail if
239 * memory allocation fails and then the
240 * number of _possible_ groups has been
241 * increased on some sockets which is ok.
242 */
243 break;
244 }
245 }
246 rcu_read_unlock();
247 netlink_table_ungrab();
248 } else {
249 err = netlink_change_ngroups(init_net.genl_sock,
250 mc_groups_longs * BITS_PER_LONG);
251 }
252
253 if (groups_allocated && err) {
254 for (i = 0; i < family->n_mcgrps; i++)
255 clear_bit(family->mcgrp_offset + i, mc_groups);
256 }
257
258 return err;
259}
260
261static void genl_unregister_mc_groups(const struct genl_family *family)
262{
263 struct net *net;
264 int i;
265
266 netlink_table_grab();
267 rcu_read_lock();
268 for_each_net_rcu(net) {
269 for (i = 0; i < family->n_mcgrps; i++)
270 __netlink_clear_multicast_users(
271 net->genl_sock, family->mcgrp_offset + i);
272 }
273 rcu_read_unlock();
274 netlink_table_ungrab();
275
276 for (i = 0; i < family->n_mcgrps; i++) {
277 int grp_id = family->mcgrp_offset + i;
278
279 if (grp_id != 1)
280 clear_bit(grp_id, mc_groups);
281 genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, family,
282 &family->mcgrps[i], grp_id);
283 }
284}
285
286static int genl_validate_ops(const struct genl_family *family)
287{
288 const struct genl_ops *ops = family->ops;
289 unsigned int n_ops = family->n_ops;
290 int i, j;
291
292 if (WARN_ON(n_ops && !ops))
293 return -EINVAL;
294
295 if (!n_ops)
296 return 0;
297
298 for (i = 0; i < n_ops; i++) {
299 if (ops[i].dumpit == NULL && ops[i].doit == NULL)
300 return -EINVAL;
301 for (j = i + 1; j < n_ops; j++)
302 if (ops[i].cmd == ops[j].cmd)
303 return -EINVAL;
304 }
305
306 return 0;
307}
308
309/**
310 * genl_register_family - register a generic netlink family
311 * @family: generic netlink family
312 *
313 * Registers the specified family after validating it first. Only one
314 * family may be registered with the same family name or identifier.
315 *
316 * The family's ops, multicast groups and module pointer must already
317 * be assigned.
318 *
319 * Return 0 on success or a negative error code.
320 */
321int genl_register_family(struct genl_family *family)
322{
323 int err, i;
324 int start = GENL_START_ALLOC, end = GENL_MAX_ID;
325
326 err = genl_validate_ops(family);
327 if (err)
328 return err;
329
330 genl_lock_all();
331
332 if (genl_family_find_byname(family->name)) {
333 err = -EEXIST;
334 goto errout_locked;
335 }
336
337 /*
338 * Sadly, a few cases need to be special-cased
339 * due to them having previously abused the API
340 * and having used their family ID also as their
341 * multicast group ID, so we use reserved IDs
342 * for both to be sure we can do that mapping.
343 */
344 if (family == &genl_ctrl) {
345 /* and this needs to be special for initial family lookups */
346 start = end = GENL_ID_CTRL;
347 } else if (strcmp(family->name, "pmcraid") == 0) {
348 start = end = GENL_ID_PMCRAID;
349 } else if (strcmp(family->name, "VFS_DQUOT") == 0) {
350 start = end = GENL_ID_VFS_DQUOT;
351 }
352
353 if (family->maxattr && !family->parallel_ops) {
354 family->attrbuf = kmalloc((family->maxattr+1) *
355 sizeof(struct nlattr *), GFP_KERNEL);
356 if (family->attrbuf == NULL) {
357 err = -ENOMEM;
358 goto errout_locked;
359 }
360 } else
361 family->attrbuf = NULL;
362
363 family->id = idr_alloc(&genl_fam_idr, family,
364 start, end + 1, GFP_KERNEL);
365 if (family->id < 0) {
366 err = family->id;
367 goto errout_locked;
368 }
369
370 err = genl_validate_assign_mc_groups(family);
371 if (err)
372 goto errout_remove;
373
374 genl_unlock_all();
375
376 /* send all events */
377 genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0);
378 for (i = 0; i < family->n_mcgrps; i++)
379 genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family,
380 &family->mcgrps[i], family->mcgrp_offset + i);
381
382 return 0;
383
384errout_remove:
385 idr_remove(&genl_fam_idr, family->id);
386 kfree(family->attrbuf);
387errout_locked:
388 genl_unlock_all();
389 return err;
390}
391EXPORT_SYMBOL(genl_register_family);
392
393/**
394 * genl_unregister_family - unregister generic netlink family
395 * @family: generic netlink family
396 *
397 * Unregisters the specified family.
398 *
399 * Returns 0 on success or a negative error code.
400 */
401int genl_unregister_family(const struct genl_family *family)
402{
403 genl_lock_all();
404
405 if (!genl_family_find_byid(family->id)) {
406 genl_unlock_all();
407 return -ENOENT;
408 }
409
410 genl_unregister_mc_groups(family);
411
412 idr_remove(&genl_fam_idr, family->id);
413
414 up_write(&cb_lock);
415 wait_event(genl_sk_destructing_waitq,
416 atomic_read(&genl_sk_destructing_cnt) == 0);
417 genl_unlock();
418
419 kfree(family->attrbuf);
420
421 genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
422
423 return 0;
424}
425EXPORT_SYMBOL(genl_unregister_family);
426
427/**
428 * genlmsg_put - Add generic netlink header to netlink message
429 * @skb: socket buffer holding the message
430 * @portid: netlink portid the message is addressed to
431 * @seq: sequence number (usually the one of the sender)
432 * @family: generic netlink family
433 * @flags: netlink message flags
434 * @cmd: generic netlink command
435 *
436 * Returns pointer to user specific header
437 */
438void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
439 const struct genl_family *family, int flags, u8 cmd)
440{
441 struct nlmsghdr *nlh;
442 struct genlmsghdr *hdr;
443
444 nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
445 family->hdrsize, flags);
446 if (nlh == NULL)
447 return NULL;
448
449 hdr = nlmsg_data(nlh);
450 hdr->cmd = cmd;
451 hdr->version = family->version;
452 hdr->reserved = 0;
453
454 return (char *) hdr + GENL_HDRLEN;
455}
456EXPORT_SYMBOL(genlmsg_put);
457
458static int genl_lock_start(struct netlink_callback *cb)
459{
460 /* our ops are always const - netlink API doesn't propagate that */
461 const struct genl_ops *ops = cb->data;
462 int rc = 0;
463
464 if (ops->start) {
465 genl_lock();
466 rc = ops->start(cb);
467 genl_unlock();
468 }
469 return rc;
470}
471
472static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
473{
474 /* our ops are always const - netlink API doesn't propagate that */
475 const struct genl_ops *ops = cb->data;
476 int rc;
477
478 genl_lock();
479 rc = ops->dumpit(skb, cb);
480 genl_unlock();
481 return rc;
482}
483
484static int genl_lock_done(struct netlink_callback *cb)
485{
486 /* our ops are always const - netlink API doesn't propagate that */
487 const struct genl_ops *ops = cb->data;
488 int rc = 0;
489
490 if (ops->done) {
491 genl_lock();
492 rc = ops->done(cb);
493 genl_unlock();
494 }
495 return rc;
496}
497
498static int genl_family_rcv_msg(const struct genl_family *family,
499 struct sk_buff *skb,
500 struct nlmsghdr *nlh)
501{
502 const struct genl_ops *ops;
503 struct net *net = sock_net(skb->sk);
504 struct genl_info info;
505 struct genlmsghdr *hdr = nlmsg_data(nlh);
506 struct nlattr **attrbuf;
507 int hdrlen, err;
508
509 /* this family doesn't exist in this netns */
510 if (!family->netnsok && !net_eq(net, &init_net))
511 return -ENOENT;
512
513 hdrlen = GENL_HDRLEN + family->hdrsize;
514 if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
515 return -EINVAL;
516
517 ops = genl_get_cmd(hdr->cmd, family);
518 if (ops == NULL)
519 return -EOPNOTSUPP;
520
521 if ((ops->flags & GENL_ADMIN_PERM) &&
522 !netlink_capable(skb, CAP_NET_ADMIN))
523 return -EPERM;
524
525 if ((ops->flags & GENL_UNS_ADMIN_PERM) &&
526 !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
527 return -EPERM;
528
529 if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
530 int rc;
531
532 if (ops->dumpit == NULL)
533 return -EOPNOTSUPP;
534
535 if (!family->parallel_ops) {
536 struct netlink_dump_control c = {
537 .module = family->module,
538 /* we have const, but the netlink API doesn't */
539 .data = (void *)ops,
540 .start = genl_lock_start,
541 .dump = genl_lock_dumpit,
542 .done = genl_lock_done,
543 };
544
545 genl_unlock();
546 rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
547 genl_lock();
548
549 } else {
550 struct netlink_dump_control c = {
551 .module = family->module,
552 .start = ops->start,
553 .dump = ops->dumpit,
554 .done = ops->done,
555 };
556
557 rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
558 }
559
560 return rc;
561 }
562
563 if (ops->doit == NULL)
564 return -EOPNOTSUPP;
565
566 if (family->maxattr && family->parallel_ops) {
567 attrbuf = kmalloc((family->maxattr+1) *
568 sizeof(struct nlattr *), GFP_KERNEL);
569 if (attrbuf == NULL)
570 return -ENOMEM;
571 } else
572 attrbuf = family->attrbuf;
573
574 if (attrbuf) {
575 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
576 ops->policy);
577 if (err < 0)
578 goto out;
579 }
580
581 info.snd_seq = nlh->nlmsg_seq;
582 info.snd_portid = NETLINK_CB(skb).portid;
583 info.nlhdr = nlh;
584 info.genlhdr = nlmsg_data(nlh);
585 info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
586 info.attrs = attrbuf;
587 genl_info_net_set(&info, net);
588 memset(&info.user_ptr, 0, sizeof(info.user_ptr));
589
590 if (family->pre_doit) {
591 err = family->pre_doit(ops, skb, &info);
592 if (err)
593 goto out;
594 }
595
596 err = ops->doit(skb, &info);
597
598 if (family->post_doit)
599 family->post_doit(ops, skb, &info);
600
601out:
602 if (family->parallel_ops)
603 kfree(attrbuf);
604
605 return err;
606}
607
608static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
609{
610 const struct genl_family *family;
611 int err;
612
613 family = genl_family_find_byid(nlh->nlmsg_type);
614 if (family == NULL)
615 return -ENOENT;
616
617 if (!family->parallel_ops)
618 genl_lock();
619
620 err = genl_family_rcv_msg(family, skb, nlh);
621
622 if (!family->parallel_ops)
623 genl_unlock();
624
625 return err;
626}
627
628static void genl_rcv(struct sk_buff *skb)
629{
630 down_read(&cb_lock);
631 netlink_rcv_skb(skb, &genl_rcv_msg);
632 up_read(&cb_lock);
633}
634
635/**************************************************************************
636 * Controller
637 **************************************************************************/
638
639static struct genl_family genl_ctrl;
640
641static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
642 u32 flags, struct sk_buff *skb, u8 cmd)
643{
644 void *hdr;
645
646 hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
647 if (hdr == NULL)
648 return -1;
649
650 if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
651 nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
652 nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
653 nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
654 nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
655 goto nla_put_failure;
656
657 if (family->n_ops) {
658 struct nlattr *nla_ops;
659 int i;
660
661 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
662 if (nla_ops == NULL)
663 goto nla_put_failure;
664
665 for (i = 0; i < family->n_ops; i++) {
666 struct nlattr *nest;
667 const struct genl_ops *ops = &family->ops[i];
668 u32 op_flags = ops->flags;
669
670 if (ops->dumpit)
671 op_flags |= GENL_CMD_CAP_DUMP;
672 if (ops->doit)
673 op_flags |= GENL_CMD_CAP_DO;
674 if (ops->policy)
675 op_flags |= GENL_CMD_CAP_HASPOL;
676
677 nest = nla_nest_start(skb, i + 1);
678 if (nest == NULL)
679 goto nla_put_failure;
680
681 if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
682 nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
683 goto nla_put_failure;
684
685 nla_nest_end(skb, nest);
686 }
687
688 nla_nest_end(skb, nla_ops);
689 }
690
691 if (family->n_mcgrps) {
692 struct nlattr *nla_grps;
693 int i;
694
695 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
696 if (nla_grps == NULL)
697 goto nla_put_failure;
698
699 for (i = 0; i < family->n_mcgrps; i++) {
700 struct nlattr *nest;
701 const struct genl_multicast_group *grp;
702
703 grp = &family->mcgrps[i];
704
705 nest = nla_nest_start(skb, i + 1);
706 if (nest == NULL)
707 goto nla_put_failure;
708
709 if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
710 family->mcgrp_offset + i) ||
711 nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
712 grp->name))
713 goto nla_put_failure;
714
715 nla_nest_end(skb, nest);
716 }
717 nla_nest_end(skb, nla_grps);
718 }
719
720 genlmsg_end(skb, hdr);
721 return 0;
722
723nla_put_failure:
724 genlmsg_cancel(skb, hdr);
725 return -EMSGSIZE;
726}
727
728static int ctrl_fill_mcgrp_info(const struct genl_family *family,
729 const struct genl_multicast_group *grp,
730 int grp_id, u32 portid, u32 seq, u32 flags,
731 struct sk_buff *skb, u8 cmd)
732{
733 void *hdr;
734 struct nlattr *nla_grps;
735 struct nlattr *nest;
736
737 hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
738 if (hdr == NULL)
739 return -1;
740
741 if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
742 nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
743 goto nla_put_failure;
744
745 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
746 if (nla_grps == NULL)
747 goto nla_put_failure;
748
749 nest = nla_nest_start(skb, 1);
750 if (nest == NULL)
751 goto nla_put_failure;
752
753 if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
754 nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
755 grp->name))
756 goto nla_put_failure;
757
758 nla_nest_end(skb, nest);
759 nla_nest_end(skb, nla_grps);
760
761 genlmsg_end(skb, hdr);
762 return 0;
763
764nla_put_failure:
765 genlmsg_cancel(skb, hdr);
766 return -EMSGSIZE;
767}
768
769static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
770{
771 int n = 0;
772 struct genl_family *rt;
773 struct net *net = sock_net(skb->sk);
774 int fams_to_skip = cb->args[0];
775 unsigned int id;
776
777 idr_for_each_entry(&genl_fam_idr, rt, id) {
778 if (!rt->netnsok && !net_eq(net, &init_net))
779 continue;
780
781 if (n++ < fams_to_skip)
782 continue;
783
784 if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
785 cb->nlh->nlmsg_seq, NLM_F_MULTI,
786 skb, CTRL_CMD_NEWFAMILY) < 0) {
787 n--;
788 break;
789 }
790 }
791
792 cb->args[0] = n;
793 return skb->len;
794}
795
796static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family,
797 u32 portid, int seq, u8 cmd)
798{
799 struct sk_buff *skb;
800 int err;
801
802 skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
803 if (skb == NULL)
804 return ERR_PTR(-ENOBUFS);
805
806 err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
807 if (err < 0) {
808 nlmsg_free(skb);
809 return ERR_PTR(err);
810 }
811
812 return skb;
813}
814
815static struct sk_buff *
816ctrl_build_mcgrp_msg(const struct genl_family *family,
817 const struct genl_multicast_group *grp,
818 int grp_id, u32 portid, int seq, u8 cmd)
819{
820 struct sk_buff *skb;
821 int err;
822
823 skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
824 if (skb == NULL)
825 return ERR_PTR(-ENOBUFS);
826
827 err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
828 seq, 0, skb, cmd);
829 if (err < 0) {
830 nlmsg_free(skb);
831 return ERR_PTR(err);
832 }
833
834 return skb;
835}
836
837static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
838 [CTRL_ATTR_FAMILY_ID] = { .type = NLA_U16 },
839 [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
840 .len = GENL_NAMSIZ - 1 },
841};
842
843static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
844{
845 struct sk_buff *msg;
846 const struct genl_family *res = NULL;
847 int err = -EINVAL;
848
849 if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
850 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
851 res = genl_family_find_byid(id);
852 err = -ENOENT;
853 }
854
855 if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
856 char *name;
857
858 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
859 res = genl_family_find_byname(name);
860#ifdef CONFIG_MODULES
861 if (res == NULL) {
862 genl_unlock();
863 up_read(&cb_lock);
864 request_module("net-pf-%d-proto-%d-family-%s",
865 PF_NETLINK, NETLINK_GENERIC, name);
866 down_read(&cb_lock);
867 genl_lock();
868 res = genl_family_find_byname(name);
869 }
870#endif
871 err = -ENOENT;
872 }
873
874 if (res == NULL)
875 return err;
876
877 if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
878 /* family doesn't exist here */
879 return -ENOENT;
880 }
881
882 msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
883 CTRL_CMD_NEWFAMILY);
884 if (IS_ERR(msg))
885 return PTR_ERR(msg);
886
887 return genlmsg_reply(msg, info);
888}
889
890static int genl_ctrl_event(int event, const struct genl_family *family,
891 const struct genl_multicast_group *grp,
892 int grp_id)
893{
894 struct sk_buff *msg;
895
896 /* genl is still initialising */
897 if (!init_net.genl_sock)
898 return 0;
899
900 switch (event) {
901 case CTRL_CMD_NEWFAMILY:
902 case CTRL_CMD_DELFAMILY:
903 WARN_ON(grp);
904 msg = ctrl_build_family_msg(family, 0, 0, event);
905 break;
906 case CTRL_CMD_NEWMCAST_GRP:
907 case CTRL_CMD_DELMCAST_GRP:
908 BUG_ON(!grp);
909 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
910 break;
911 default:
912 return -EINVAL;
913 }
914
915 if (IS_ERR(msg))
916 return PTR_ERR(msg);
917
918 if (!family->netnsok) {
919 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
920 0, GFP_KERNEL);
921 } else {
922 rcu_read_lock();
923 genlmsg_multicast_allns(&genl_ctrl, msg, 0,
924 0, GFP_ATOMIC);
925 rcu_read_unlock();
926 }
927
928 return 0;
929}
930
931static const struct genl_ops genl_ctrl_ops[] = {
932 {
933 .cmd = CTRL_CMD_GETFAMILY,
934 .doit = ctrl_getfamily,
935 .dumpit = ctrl_dumpfamily,
936 .policy = ctrl_policy,
937 },
938};
939
940static const struct genl_multicast_group genl_ctrl_groups[] = {
941 { .name = "notify", },
942};
943
944static struct genl_family genl_ctrl __ro_after_init = {
945 .module = THIS_MODULE,
946 .ops = genl_ctrl_ops,
947 .n_ops = ARRAY_SIZE(genl_ctrl_ops),
948 .mcgrps = genl_ctrl_groups,
949 .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups),
950 .id = GENL_ID_CTRL,
951 .name = "nlctrl",
952 .version = 0x2,
953 .maxattr = CTRL_ATTR_MAX,
954 .netnsok = true,
955};
956
957static int genl_bind(struct net *net, int group)
958{
959 struct genl_family *f;
960 int err = -ENOENT;
961 unsigned int id;
962
963 down_read(&cb_lock);
964
965 idr_for_each_entry(&genl_fam_idr, f, id) {
966 if (group >= f->mcgrp_offset &&
967 group < f->mcgrp_offset + f->n_mcgrps) {
968 int fam_grp = group - f->mcgrp_offset;
969
970 if (!f->netnsok && net != &init_net)
971 err = -ENOENT;
972 else if (f->mcast_bind)
973 err = f->mcast_bind(net, fam_grp);
974 else
975 err = 0;
976 break;
977 }
978 }
979 up_read(&cb_lock);
980
981 return err;
982}
983
984static void genl_unbind(struct net *net, int group)
985{
986 struct genl_family *f;
987 unsigned int id;
988
989 down_read(&cb_lock);
990
991 idr_for_each_entry(&genl_fam_idr, f, id) {
992 if (group >= f->mcgrp_offset &&
993 group < f->mcgrp_offset + f->n_mcgrps) {
994 int fam_grp = group - f->mcgrp_offset;
995
996 if (f->mcast_unbind)
997 f->mcast_unbind(net, fam_grp);
998 break;
999 }
1000 }
1001 up_read(&cb_lock);
1002}
1003
1004static int __net_init genl_pernet_init(struct net *net)
1005{
1006 struct netlink_kernel_cfg cfg = {
1007 .input = genl_rcv,
1008 .flags = NL_CFG_F_NONROOT_RECV,
1009 .bind = genl_bind,
1010 .unbind = genl_unbind,
1011 };
1012
1013 /* we'll bump the group number right afterwards */
1014 net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
1015
1016 if (!net->genl_sock && net_eq(net, &init_net))
1017 panic("GENL: Cannot initialize generic netlink\n");
1018
1019 if (!net->genl_sock)
1020 return -ENOMEM;
1021
1022 return 0;
1023}
1024
1025static void __net_exit genl_pernet_exit(struct net *net)
1026{
1027 netlink_kernel_release(net->genl_sock);
1028 net->genl_sock = NULL;
1029}
1030
1031static struct pernet_operations genl_pernet_ops = {
1032 .init = genl_pernet_init,
1033 .exit = genl_pernet_exit,
1034};
1035
1036static int __init genl_init(void)
1037{
1038 int err;
1039
1040 err = genl_register_family(&genl_ctrl);
1041 if (err < 0)
1042 goto problem;
1043
1044 err = register_pernet_subsys(&genl_pernet_ops);
1045 if (err)
1046 goto problem;
1047
1048 return 0;
1049
1050problem:
1051 panic("GENL: Cannot register controller: %d\n", err);
1052}
1053
1054subsys_initcall(genl_init);
1055
1056/**
1057 * genl_family_attrbuf - return family's attrbuf
1058 * @family: the family
1059 *
1060 * Return the family's attrbuf, while validating that it's
1061 * actually valid to access it.
1062 *
1063 * You cannot use this function with a family that has parallel_ops
1064 * and you can only use it within (pre/post) doit/dumpit callbacks.
1065 */
1066struct nlattr **genl_family_attrbuf(const struct genl_family *family)
1067{
1068 if (!WARN_ON(family->parallel_ops))
1069 lockdep_assert_held(&genl_mutex);
1070
1071 return family->attrbuf;
1072}
1073EXPORT_SYMBOL(genl_family_attrbuf);
1074
1075static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
1076 gfp_t flags)
1077{
1078 struct sk_buff *tmp;
1079 struct net *net, *prev = NULL;
1080 int err;
1081
1082 for_each_net_rcu(net) {
1083 if (prev) {
1084 tmp = skb_clone(skb, flags);
1085 if (!tmp) {
1086 err = -ENOMEM;
1087 goto error;
1088 }
1089 err = nlmsg_multicast(prev->genl_sock, tmp,
1090 portid, group, flags);
1091 if (err)
1092 goto error;
1093 }
1094
1095 prev = net;
1096 }
1097
1098 return nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1099 error:
1100 kfree_skb(skb);
1101 return err;
1102}
1103
1104int genlmsg_multicast_allns(const struct genl_family *family,
1105 struct sk_buff *skb, u32 portid,
1106 unsigned int group, gfp_t flags)
1107{
1108 if (WARN_ON_ONCE(group >= family->n_mcgrps))
1109 return -EINVAL;
1110 group = family->mcgrp_offset + group;
1111 return genlmsg_mcast(skb, portid, group, flags);
1112}
1113EXPORT_SYMBOL(genlmsg_multicast_allns);
1114
1115void genl_notify(const struct genl_family *family, struct sk_buff *skb,
1116 struct genl_info *info, u32 group, gfp_t flags)
1117{
1118 struct net *net = genl_info_net(info);
1119 struct sock *sk = net->genl_sock;
1120 int report = 0;
1121
1122 if (info->nlhdr)
1123 report = nlmsg_report(info->nlhdr);
1124
1125 if (WARN_ON_ONCE(group >= family->n_mcgrps))
1126 return;
1127 group = family->mcgrp_offset + group;
1128 nlmsg_notify(sk, skb, info->snd_portid, group, report, flags);
1129}
1130EXPORT_SYMBOL(genl_notify);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * NETLINK Generic Netlink Family
4 *
5 * Authors: Jamal Hadi Salim
6 * Thomas Graf <tgraf@suug.ch>
7 * Johannes Berg <johannes@sipsolutions.net>
8 */
9
10#include <linux/module.h>
11#include <linux/kernel.h>
12#include <linux/slab.h>
13#include <linux/errno.h>
14#include <linux/types.h>
15#include <linux/socket.h>
16#include <linux/string.h>
17#include <linux/skbuff.h>
18#include <linux/mutex.h>
19#include <linux/bitmap.h>
20#include <linux/rwsem.h>
21#include <linux/idr.h>
22#include <net/sock.h>
23#include <net/genetlink.h>
24
25static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
26static DECLARE_RWSEM(cb_lock);
27
28atomic_t genl_sk_destructing_cnt = ATOMIC_INIT(0);
29DECLARE_WAIT_QUEUE_HEAD(genl_sk_destructing_waitq);
30
31void genl_lock(void)
32{
33 mutex_lock(&genl_mutex);
34}
35EXPORT_SYMBOL(genl_lock);
36
37void genl_unlock(void)
38{
39 mutex_unlock(&genl_mutex);
40}
41EXPORT_SYMBOL(genl_unlock);
42
43#ifdef CONFIG_LOCKDEP
44bool lockdep_genl_is_held(void)
45{
46 return lockdep_is_held(&genl_mutex);
47}
48EXPORT_SYMBOL(lockdep_genl_is_held);
49#endif
50
51static void genl_lock_all(void)
52{
53 down_write(&cb_lock);
54 genl_lock();
55}
56
57static void genl_unlock_all(void)
58{
59 genl_unlock();
60 up_write(&cb_lock);
61}
62
63static DEFINE_IDR(genl_fam_idr);
64
65/*
66 * Bitmap of multicast groups that are currently in use.
67 *
68 * To avoid an allocation at boot of just one unsigned long,
69 * declare it global instead.
70 * Bit 0 is marked as already used since group 0 is invalid.
71 * Bit 1 is marked as already used since the drop-monitor code
72 * abuses the API and thinks it can statically use group 1.
73 * That group will typically conflict with other groups that
74 * any proper users use.
75 * Bit 16 is marked as used since it's used for generic netlink
76 * and the code no longer marks pre-reserved IDs as used.
77 * Bit 17 is marked as already used since the VFS quota code
78 * also abused this API and relied on family == group ID, we
79 * cater to that by giving it a static family and group ID.
80 * Bit 18 is marked as already used since the PMCRAID driver
81 * did the same thing as the VFS quota code (maybe copied?)
82 */
83static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) |
84 BIT(GENL_ID_VFS_DQUOT) |
85 BIT(GENL_ID_PMCRAID);
86static unsigned long *mc_groups = &mc_group_start;
87static unsigned long mc_groups_longs = 1;
88
89static int genl_ctrl_event(int event, const struct genl_family *family,
90 const struct genl_multicast_group *grp,
91 int grp_id);
92
93static const struct genl_family *genl_family_find_byid(unsigned int id)
94{
95 return idr_find(&genl_fam_idr, id);
96}
97
98static const struct genl_family *genl_family_find_byname(char *name)
99{
100 const struct genl_family *family;
101 unsigned int id;
102
103 idr_for_each_entry(&genl_fam_idr, family, id)
104 if (strcmp(family->name, name) == 0)
105 return family;
106
107 return NULL;
108}
109
110static const struct genl_ops *genl_get_cmd(u8 cmd,
111 const struct genl_family *family)
112{
113 int i;
114
115 for (i = 0; i < family->n_ops; i++)
116 if (family->ops[i].cmd == cmd)
117 return &family->ops[i];
118
119 return NULL;
120}
121
122static int genl_allocate_reserve_groups(int n_groups, int *first_id)
123{
124 unsigned long *new_groups;
125 int start = 0;
126 int i;
127 int id;
128 bool fits;
129
130 do {
131 if (start == 0)
132 id = find_first_zero_bit(mc_groups,
133 mc_groups_longs *
134 BITS_PER_LONG);
135 else
136 id = find_next_zero_bit(mc_groups,
137 mc_groups_longs * BITS_PER_LONG,
138 start);
139
140 fits = true;
141 for (i = id;
142 i < min_t(int, id + n_groups,
143 mc_groups_longs * BITS_PER_LONG);
144 i++) {
145 if (test_bit(i, mc_groups)) {
146 start = i;
147 fits = false;
148 break;
149 }
150 }
151
152 if (id + n_groups > mc_groups_longs * BITS_PER_LONG) {
153 unsigned long new_longs = mc_groups_longs +
154 BITS_TO_LONGS(n_groups);
155 size_t nlen = new_longs * sizeof(unsigned long);
156
157 if (mc_groups == &mc_group_start) {
158 new_groups = kzalloc(nlen, GFP_KERNEL);
159 if (!new_groups)
160 return -ENOMEM;
161 mc_groups = new_groups;
162 *mc_groups = mc_group_start;
163 } else {
164 new_groups = krealloc(mc_groups, nlen,
165 GFP_KERNEL);
166 if (!new_groups)
167 return -ENOMEM;
168 mc_groups = new_groups;
169 for (i = 0; i < BITS_TO_LONGS(n_groups); i++)
170 mc_groups[mc_groups_longs + i] = 0;
171 }
172 mc_groups_longs = new_longs;
173 }
174 } while (!fits);
175
176 for (i = id; i < id + n_groups; i++)
177 set_bit(i, mc_groups);
178 *first_id = id;
179 return 0;
180}
181
182static struct genl_family genl_ctrl;
183
184static int genl_validate_assign_mc_groups(struct genl_family *family)
185{
186 int first_id;
187 int n_groups = family->n_mcgrps;
188 int err = 0, i;
189 bool groups_allocated = false;
190
191 if (!n_groups)
192 return 0;
193
194 for (i = 0; i < n_groups; i++) {
195 const struct genl_multicast_group *grp = &family->mcgrps[i];
196
197 if (WARN_ON(grp->name[0] == '\0'))
198 return -EINVAL;
199 if (WARN_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL))
200 return -EINVAL;
201 }
202
203 /* special-case our own group and hacks */
204 if (family == &genl_ctrl) {
205 first_id = GENL_ID_CTRL;
206 BUG_ON(n_groups != 1);
207 } else if (strcmp(family->name, "NET_DM") == 0) {
208 first_id = 1;
209 BUG_ON(n_groups != 1);
210 } else if (family->id == GENL_ID_VFS_DQUOT) {
211 first_id = GENL_ID_VFS_DQUOT;
212 BUG_ON(n_groups != 1);
213 } else if (family->id == GENL_ID_PMCRAID) {
214 first_id = GENL_ID_PMCRAID;
215 BUG_ON(n_groups != 1);
216 } else {
217 groups_allocated = true;
218 err = genl_allocate_reserve_groups(n_groups, &first_id);
219 if (err)
220 return err;
221 }
222
223 family->mcgrp_offset = first_id;
224
225 /* if still initializing, can't and don't need to to realloc bitmaps */
226 if (!init_net.genl_sock)
227 return 0;
228
229 if (family->netnsok) {
230 struct net *net;
231
232 netlink_table_grab();
233 rcu_read_lock();
234 for_each_net_rcu(net) {
235 err = __netlink_change_ngroups(net->genl_sock,
236 mc_groups_longs * BITS_PER_LONG);
237 if (err) {
238 /*
239 * No need to roll back, can only fail if
240 * memory allocation fails and then the
241 * number of _possible_ groups has been
242 * increased on some sockets which is ok.
243 */
244 break;
245 }
246 }
247 rcu_read_unlock();
248 netlink_table_ungrab();
249 } else {
250 err = netlink_change_ngroups(init_net.genl_sock,
251 mc_groups_longs * BITS_PER_LONG);
252 }
253
254 if (groups_allocated && err) {
255 for (i = 0; i < family->n_mcgrps; i++)
256 clear_bit(family->mcgrp_offset + i, mc_groups);
257 }
258
259 return err;
260}
261
262static void genl_unregister_mc_groups(const struct genl_family *family)
263{
264 struct net *net;
265 int i;
266
267 netlink_table_grab();
268 rcu_read_lock();
269 for_each_net_rcu(net) {
270 for (i = 0; i < family->n_mcgrps; i++)
271 __netlink_clear_multicast_users(
272 net->genl_sock, family->mcgrp_offset + i);
273 }
274 rcu_read_unlock();
275 netlink_table_ungrab();
276
277 for (i = 0; i < family->n_mcgrps; i++) {
278 int grp_id = family->mcgrp_offset + i;
279
280 if (grp_id != 1)
281 clear_bit(grp_id, mc_groups);
282 genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, family,
283 &family->mcgrps[i], grp_id);
284 }
285}
286
287static int genl_validate_ops(const struct genl_family *family)
288{
289 const struct genl_ops *ops = family->ops;
290 unsigned int n_ops = family->n_ops;
291 int i, j;
292
293 if (WARN_ON(n_ops && !ops))
294 return -EINVAL;
295
296 if (!n_ops)
297 return 0;
298
299 for (i = 0; i < n_ops; i++) {
300 if (ops[i].dumpit == NULL && ops[i].doit == NULL)
301 return -EINVAL;
302 for (j = i + 1; j < n_ops; j++)
303 if (ops[i].cmd == ops[j].cmd)
304 return -EINVAL;
305 }
306
307 return 0;
308}
309
310/**
311 * genl_register_family - register a generic netlink family
312 * @family: generic netlink family
313 *
314 * Registers the specified family after validating it first. Only one
315 * family may be registered with the same family name or identifier.
316 *
317 * The family's ops, multicast groups and module pointer must already
318 * be assigned.
319 *
320 * Return 0 on success or a negative error code.
321 */
322int genl_register_family(struct genl_family *family)
323{
324 int err, i;
325 int start = GENL_START_ALLOC, end = GENL_MAX_ID;
326
327 err = genl_validate_ops(family);
328 if (err)
329 return err;
330
331 genl_lock_all();
332
333 if (genl_family_find_byname(family->name)) {
334 err = -EEXIST;
335 goto errout_locked;
336 }
337
338 /*
339 * Sadly, a few cases need to be special-cased
340 * due to them having previously abused the API
341 * and having used their family ID also as their
342 * multicast group ID, so we use reserved IDs
343 * for both to be sure we can do that mapping.
344 */
345 if (family == &genl_ctrl) {
346 /* and this needs to be special for initial family lookups */
347 start = end = GENL_ID_CTRL;
348 } else if (strcmp(family->name, "pmcraid") == 0) {
349 start = end = GENL_ID_PMCRAID;
350 } else if (strcmp(family->name, "VFS_DQUOT") == 0) {
351 start = end = GENL_ID_VFS_DQUOT;
352 }
353
354 if (family->maxattr && !family->parallel_ops) {
355 family->attrbuf = kmalloc((family->maxattr+1) *
356 sizeof(struct nlattr *), GFP_KERNEL);
357 if (family->attrbuf == NULL) {
358 err = -ENOMEM;
359 goto errout_locked;
360 }
361 } else
362 family->attrbuf = NULL;
363
364 family->id = idr_alloc(&genl_fam_idr, family,
365 start, end + 1, GFP_KERNEL);
366 if (family->id < 0) {
367 err = family->id;
368 goto errout_locked;
369 }
370
371 err = genl_validate_assign_mc_groups(family);
372 if (err)
373 goto errout_remove;
374
375 genl_unlock_all();
376
377 /* send all events */
378 genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0);
379 for (i = 0; i < family->n_mcgrps; i++)
380 genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family,
381 &family->mcgrps[i], family->mcgrp_offset + i);
382
383 return 0;
384
385errout_remove:
386 idr_remove(&genl_fam_idr, family->id);
387 kfree(family->attrbuf);
388errout_locked:
389 genl_unlock_all();
390 return err;
391}
392EXPORT_SYMBOL(genl_register_family);
393
394/**
395 * genl_unregister_family - unregister generic netlink family
396 * @family: generic netlink family
397 *
398 * Unregisters the specified family.
399 *
400 * Returns 0 on success or a negative error code.
401 */
402int genl_unregister_family(const struct genl_family *family)
403{
404 genl_lock_all();
405
406 if (!genl_family_find_byid(family->id)) {
407 genl_unlock_all();
408 return -ENOENT;
409 }
410
411 genl_unregister_mc_groups(family);
412
413 idr_remove(&genl_fam_idr, family->id);
414
415 up_write(&cb_lock);
416 wait_event(genl_sk_destructing_waitq,
417 atomic_read(&genl_sk_destructing_cnt) == 0);
418 genl_unlock();
419
420 kfree(family->attrbuf);
421
422 genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
423
424 return 0;
425}
426EXPORT_SYMBOL(genl_unregister_family);
427
428/**
429 * genlmsg_put - Add generic netlink header to netlink message
430 * @skb: socket buffer holding the message
431 * @portid: netlink portid the message is addressed to
432 * @seq: sequence number (usually the one of the sender)
433 * @family: generic netlink family
434 * @flags: netlink message flags
435 * @cmd: generic netlink command
436 *
437 * Returns pointer to user specific header
438 */
439void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
440 const struct genl_family *family, int flags, u8 cmd)
441{
442 struct nlmsghdr *nlh;
443 struct genlmsghdr *hdr;
444
445 nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
446 family->hdrsize, flags);
447 if (nlh == NULL)
448 return NULL;
449
450 hdr = nlmsg_data(nlh);
451 hdr->cmd = cmd;
452 hdr->version = family->version;
453 hdr->reserved = 0;
454
455 return (char *) hdr + GENL_HDRLEN;
456}
457EXPORT_SYMBOL(genlmsg_put);
458
459static int genl_lock_start(struct netlink_callback *cb)
460{
461 /* our ops are always const - netlink API doesn't propagate that */
462 const struct genl_ops *ops = cb->data;
463 int rc = 0;
464
465 if (ops->start) {
466 genl_lock();
467 rc = ops->start(cb);
468 genl_unlock();
469 }
470 return rc;
471}
472
473static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
474{
475 /* our ops are always const - netlink API doesn't propagate that */
476 const struct genl_ops *ops = cb->data;
477 int rc;
478
479 genl_lock();
480 rc = ops->dumpit(skb, cb);
481 genl_unlock();
482 return rc;
483}
484
485static int genl_lock_done(struct netlink_callback *cb)
486{
487 /* our ops are always const - netlink API doesn't propagate that */
488 const struct genl_ops *ops = cb->data;
489 int rc = 0;
490
491 if (ops->done) {
492 genl_lock();
493 rc = ops->done(cb);
494 genl_unlock();
495 }
496 return rc;
497}
498
499static int genl_family_rcv_msg(const struct genl_family *family,
500 struct sk_buff *skb,
501 struct nlmsghdr *nlh,
502 struct netlink_ext_ack *extack)
503{
504 const struct genl_ops *ops;
505 struct net *net = sock_net(skb->sk);
506 struct genl_info info;
507 struct genlmsghdr *hdr = nlmsg_data(nlh);
508 struct nlattr **attrbuf;
509 int hdrlen, err;
510
511 /* this family doesn't exist in this netns */
512 if (!family->netnsok && !net_eq(net, &init_net))
513 return -ENOENT;
514
515 hdrlen = GENL_HDRLEN + family->hdrsize;
516 if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
517 return -EINVAL;
518
519 ops = genl_get_cmd(hdr->cmd, family);
520 if (ops == NULL)
521 return -EOPNOTSUPP;
522
523 if ((ops->flags & GENL_ADMIN_PERM) &&
524 !netlink_capable(skb, CAP_NET_ADMIN))
525 return -EPERM;
526
527 if ((ops->flags & GENL_UNS_ADMIN_PERM) &&
528 !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
529 return -EPERM;
530
531 if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
532 int rc;
533
534 if (ops->dumpit == NULL)
535 return -EOPNOTSUPP;
536
537 if (!family->parallel_ops) {
538 struct netlink_dump_control c = {
539 .module = family->module,
540 /* we have const, but the netlink API doesn't */
541 .data = (void *)ops,
542 .start = genl_lock_start,
543 .dump = genl_lock_dumpit,
544 .done = genl_lock_done,
545 };
546
547 genl_unlock();
548 rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
549 genl_lock();
550
551 } else {
552 struct netlink_dump_control c = {
553 .module = family->module,
554 .start = ops->start,
555 .dump = ops->dumpit,
556 .done = ops->done,
557 };
558
559 rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
560 }
561
562 return rc;
563 }
564
565 if (ops->doit == NULL)
566 return -EOPNOTSUPP;
567
568 if (family->maxattr && family->parallel_ops) {
569 attrbuf = kmalloc((family->maxattr+1) *
570 sizeof(struct nlattr *), GFP_KERNEL);
571 if (attrbuf == NULL)
572 return -ENOMEM;
573 } else
574 attrbuf = family->attrbuf;
575
576 if (attrbuf) {
577 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
578 ops->policy, extack);
579 if (err < 0)
580 goto out;
581 }
582
583 info.snd_seq = nlh->nlmsg_seq;
584 info.snd_portid = NETLINK_CB(skb).portid;
585 info.nlhdr = nlh;
586 info.genlhdr = nlmsg_data(nlh);
587 info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
588 info.attrs = attrbuf;
589 info.extack = extack;
590 genl_info_net_set(&info, net);
591 memset(&info.user_ptr, 0, sizeof(info.user_ptr));
592
593 if (family->pre_doit) {
594 err = family->pre_doit(ops, skb, &info);
595 if (err)
596 goto out;
597 }
598
599 err = ops->doit(skb, &info);
600
601 if (family->post_doit)
602 family->post_doit(ops, skb, &info);
603
604out:
605 if (family->parallel_ops)
606 kfree(attrbuf);
607
608 return err;
609}
610
611static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
612 struct netlink_ext_ack *extack)
613{
614 const struct genl_family *family;
615 int err;
616
617 family = genl_family_find_byid(nlh->nlmsg_type);
618 if (family == NULL)
619 return -ENOENT;
620
621 if (!family->parallel_ops)
622 genl_lock();
623
624 err = genl_family_rcv_msg(family, skb, nlh, extack);
625
626 if (!family->parallel_ops)
627 genl_unlock();
628
629 return err;
630}
631
632static void genl_rcv(struct sk_buff *skb)
633{
634 down_read(&cb_lock);
635 netlink_rcv_skb(skb, &genl_rcv_msg);
636 up_read(&cb_lock);
637}
638
639/**************************************************************************
640 * Controller
641 **************************************************************************/
642
643static struct genl_family genl_ctrl;
644
645static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
646 u32 flags, struct sk_buff *skb, u8 cmd)
647{
648 void *hdr;
649
650 hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
651 if (hdr == NULL)
652 return -1;
653
654 if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
655 nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
656 nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
657 nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
658 nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
659 goto nla_put_failure;
660
661 if (family->n_ops) {
662 struct nlattr *nla_ops;
663 int i;
664
665 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
666 if (nla_ops == NULL)
667 goto nla_put_failure;
668
669 for (i = 0; i < family->n_ops; i++) {
670 struct nlattr *nest;
671 const struct genl_ops *ops = &family->ops[i];
672 u32 op_flags = ops->flags;
673
674 if (ops->dumpit)
675 op_flags |= GENL_CMD_CAP_DUMP;
676 if (ops->doit)
677 op_flags |= GENL_CMD_CAP_DO;
678 if (ops->policy)
679 op_flags |= GENL_CMD_CAP_HASPOL;
680
681 nest = nla_nest_start(skb, i + 1);
682 if (nest == NULL)
683 goto nla_put_failure;
684
685 if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
686 nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
687 goto nla_put_failure;
688
689 nla_nest_end(skb, nest);
690 }
691
692 nla_nest_end(skb, nla_ops);
693 }
694
695 if (family->n_mcgrps) {
696 struct nlattr *nla_grps;
697 int i;
698
699 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
700 if (nla_grps == NULL)
701 goto nla_put_failure;
702
703 for (i = 0; i < family->n_mcgrps; i++) {
704 struct nlattr *nest;
705 const struct genl_multicast_group *grp;
706
707 grp = &family->mcgrps[i];
708
709 nest = nla_nest_start(skb, i + 1);
710 if (nest == NULL)
711 goto nla_put_failure;
712
713 if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
714 family->mcgrp_offset + i) ||
715 nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
716 grp->name))
717 goto nla_put_failure;
718
719 nla_nest_end(skb, nest);
720 }
721 nla_nest_end(skb, nla_grps);
722 }
723
724 genlmsg_end(skb, hdr);
725 return 0;
726
727nla_put_failure:
728 genlmsg_cancel(skb, hdr);
729 return -EMSGSIZE;
730}
731
732static int ctrl_fill_mcgrp_info(const struct genl_family *family,
733 const struct genl_multicast_group *grp,
734 int grp_id, u32 portid, u32 seq, u32 flags,
735 struct sk_buff *skb, u8 cmd)
736{
737 void *hdr;
738 struct nlattr *nla_grps;
739 struct nlattr *nest;
740
741 hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
742 if (hdr == NULL)
743 return -1;
744
745 if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
746 nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
747 goto nla_put_failure;
748
749 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
750 if (nla_grps == NULL)
751 goto nla_put_failure;
752
753 nest = nla_nest_start(skb, 1);
754 if (nest == NULL)
755 goto nla_put_failure;
756
757 if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
758 nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
759 grp->name))
760 goto nla_put_failure;
761
762 nla_nest_end(skb, nest);
763 nla_nest_end(skb, nla_grps);
764
765 genlmsg_end(skb, hdr);
766 return 0;
767
768nla_put_failure:
769 genlmsg_cancel(skb, hdr);
770 return -EMSGSIZE;
771}
772
773static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
774{
775 int n = 0;
776 struct genl_family *rt;
777 struct net *net = sock_net(skb->sk);
778 int fams_to_skip = cb->args[0];
779 unsigned int id;
780
781 idr_for_each_entry(&genl_fam_idr, rt, id) {
782 if (!rt->netnsok && !net_eq(net, &init_net))
783 continue;
784
785 if (n++ < fams_to_skip)
786 continue;
787
788 if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
789 cb->nlh->nlmsg_seq, NLM_F_MULTI,
790 skb, CTRL_CMD_NEWFAMILY) < 0) {
791 n--;
792 break;
793 }
794 }
795
796 cb->args[0] = n;
797 return skb->len;
798}
799
800static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family,
801 u32 portid, int seq, u8 cmd)
802{
803 struct sk_buff *skb;
804 int err;
805
806 skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
807 if (skb == NULL)
808 return ERR_PTR(-ENOBUFS);
809
810 err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
811 if (err < 0) {
812 nlmsg_free(skb);
813 return ERR_PTR(err);
814 }
815
816 return skb;
817}
818
819static struct sk_buff *
820ctrl_build_mcgrp_msg(const struct genl_family *family,
821 const struct genl_multicast_group *grp,
822 int grp_id, u32 portid, int seq, u8 cmd)
823{
824 struct sk_buff *skb;
825 int err;
826
827 skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
828 if (skb == NULL)
829 return ERR_PTR(-ENOBUFS);
830
831 err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
832 seq, 0, skb, cmd);
833 if (err < 0) {
834 nlmsg_free(skb);
835 return ERR_PTR(err);
836 }
837
838 return skb;
839}
840
841static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
842 [CTRL_ATTR_FAMILY_ID] = { .type = NLA_U16 },
843 [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
844 .len = GENL_NAMSIZ - 1 },
845};
846
847static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
848{
849 struct sk_buff *msg;
850 const struct genl_family *res = NULL;
851 int err = -EINVAL;
852
853 if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
854 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
855 res = genl_family_find_byid(id);
856 err = -ENOENT;
857 }
858
859 if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
860 char *name;
861
862 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
863 res = genl_family_find_byname(name);
864#ifdef CONFIG_MODULES
865 if (res == NULL) {
866 genl_unlock();
867 up_read(&cb_lock);
868 request_module("net-pf-%d-proto-%d-family-%s",
869 PF_NETLINK, NETLINK_GENERIC, name);
870 down_read(&cb_lock);
871 genl_lock();
872 res = genl_family_find_byname(name);
873 }
874#endif
875 err = -ENOENT;
876 }
877
878 if (res == NULL)
879 return err;
880
881 if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
882 /* family doesn't exist here */
883 return -ENOENT;
884 }
885
886 msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
887 CTRL_CMD_NEWFAMILY);
888 if (IS_ERR(msg))
889 return PTR_ERR(msg);
890
891 return genlmsg_reply(msg, info);
892}
893
894static int genl_ctrl_event(int event, const struct genl_family *family,
895 const struct genl_multicast_group *grp,
896 int grp_id)
897{
898 struct sk_buff *msg;
899
900 /* genl is still initialising */
901 if (!init_net.genl_sock)
902 return 0;
903
904 switch (event) {
905 case CTRL_CMD_NEWFAMILY:
906 case CTRL_CMD_DELFAMILY:
907 WARN_ON(grp);
908 msg = ctrl_build_family_msg(family, 0, 0, event);
909 break;
910 case CTRL_CMD_NEWMCAST_GRP:
911 case CTRL_CMD_DELMCAST_GRP:
912 BUG_ON(!grp);
913 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
914 break;
915 default:
916 return -EINVAL;
917 }
918
919 if (IS_ERR(msg))
920 return PTR_ERR(msg);
921
922 if (!family->netnsok) {
923 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
924 0, GFP_KERNEL);
925 } else {
926 rcu_read_lock();
927 genlmsg_multicast_allns(&genl_ctrl, msg, 0,
928 0, GFP_ATOMIC);
929 rcu_read_unlock();
930 }
931
932 return 0;
933}
934
935static const struct genl_ops genl_ctrl_ops[] = {
936 {
937 .cmd = CTRL_CMD_GETFAMILY,
938 .doit = ctrl_getfamily,
939 .dumpit = ctrl_dumpfamily,
940 .policy = ctrl_policy,
941 },
942};
943
944static const struct genl_multicast_group genl_ctrl_groups[] = {
945 { .name = "notify", },
946};
947
948static struct genl_family genl_ctrl __ro_after_init = {
949 .module = THIS_MODULE,
950 .ops = genl_ctrl_ops,
951 .n_ops = ARRAY_SIZE(genl_ctrl_ops),
952 .mcgrps = genl_ctrl_groups,
953 .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups),
954 .id = GENL_ID_CTRL,
955 .name = "nlctrl",
956 .version = 0x2,
957 .maxattr = CTRL_ATTR_MAX,
958 .netnsok = true,
959};
960
961static int genl_bind(struct net *net, int group)
962{
963 struct genl_family *f;
964 int err = -ENOENT;
965 unsigned int id;
966
967 down_read(&cb_lock);
968
969 idr_for_each_entry(&genl_fam_idr, f, id) {
970 if (group >= f->mcgrp_offset &&
971 group < f->mcgrp_offset + f->n_mcgrps) {
972 int fam_grp = group - f->mcgrp_offset;
973
974 if (!f->netnsok && net != &init_net)
975 err = -ENOENT;
976 else if (f->mcast_bind)
977 err = f->mcast_bind(net, fam_grp);
978 else
979 err = 0;
980 break;
981 }
982 }
983 up_read(&cb_lock);
984
985 return err;
986}
987
988static void genl_unbind(struct net *net, int group)
989{
990 struct genl_family *f;
991 unsigned int id;
992
993 down_read(&cb_lock);
994
995 idr_for_each_entry(&genl_fam_idr, f, id) {
996 if (group >= f->mcgrp_offset &&
997 group < f->mcgrp_offset + f->n_mcgrps) {
998 int fam_grp = group - f->mcgrp_offset;
999
1000 if (f->mcast_unbind)
1001 f->mcast_unbind(net, fam_grp);
1002 break;
1003 }
1004 }
1005 up_read(&cb_lock);
1006}
1007
1008static int __net_init genl_pernet_init(struct net *net)
1009{
1010 struct netlink_kernel_cfg cfg = {
1011 .input = genl_rcv,
1012 .flags = NL_CFG_F_NONROOT_RECV,
1013 .bind = genl_bind,
1014 .unbind = genl_unbind,
1015 };
1016
1017 /* we'll bump the group number right afterwards */
1018 net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
1019
1020 if (!net->genl_sock && net_eq(net, &init_net))
1021 panic("GENL: Cannot initialize generic netlink\n");
1022
1023 if (!net->genl_sock)
1024 return -ENOMEM;
1025
1026 return 0;
1027}
1028
1029static void __net_exit genl_pernet_exit(struct net *net)
1030{
1031 netlink_kernel_release(net->genl_sock);
1032 net->genl_sock = NULL;
1033}
1034
1035static struct pernet_operations genl_pernet_ops = {
1036 .init = genl_pernet_init,
1037 .exit = genl_pernet_exit,
1038};
1039
1040static int __init genl_init(void)
1041{
1042 int err;
1043
1044 err = genl_register_family(&genl_ctrl);
1045 if (err < 0)
1046 goto problem;
1047
1048 err = register_pernet_subsys(&genl_pernet_ops);
1049 if (err)
1050 goto problem;
1051
1052 return 0;
1053
1054problem:
1055 panic("GENL: Cannot register controller: %d\n", err);
1056}
1057
1058subsys_initcall(genl_init);
1059
1060/**
1061 * genl_family_attrbuf - return family's attrbuf
1062 * @family: the family
1063 *
1064 * Return the family's attrbuf, while validating that it's
1065 * actually valid to access it.
1066 *
1067 * You cannot use this function with a family that has parallel_ops
1068 * and you can only use it within (pre/post) doit/dumpit callbacks.
1069 */
1070struct nlattr **genl_family_attrbuf(const struct genl_family *family)
1071{
1072 if (!WARN_ON(family->parallel_ops))
1073 lockdep_assert_held(&genl_mutex);
1074
1075 return family->attrbuf;
1076}
1077EXPORT_SYMBOL(genl_family_attrbuf);
1078
1079static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
1080 gfp_t flags)
1081{
1082 struct sk_buff *tmp;
1083 struct net *net, *prev = NULL;
1084 bool delivered = false;
1085 int err;
1086
1087 for_each_net_rcu(net) {
1088 if (prev) {
1089 tmp = skb_clone(skb, flags);
1090 if (!tmp) {
1091 err = -ENOMEM;
1092 goto error;
1093 }
1094 err = nlmsg_multicast(prev->genl_sock, tmp,
1095 portid, group, flags);
1096 if (!err)
1097 delivered = true;
1098 else if (err != -ESRCH)
1099 goto error;
1100 }
1101
1102 prev = net;
1103 }
1104
1105 err = nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1106 if (!err)
1107 delivered = true;
1108 else if (err != -ESRCH)
1109 return err;
1110 return delivered ? 0 : -ESRCH;
1111 error:
1112 kfree_skb(skb);
1113 return err;
1114}
1115
1116int genlmsg_multicast_allns(const struct genl_family *family,
1117 struct sk_buff *skb, u32 portid,
1118 unsigned int group, gfp_t flags)
1119{
1120 if (WARN_ON_ONCE(group >= family->n_mcgrps))
1121 return -EINVAL;
1122 group = family->mcgrp_offset + group;
1123 return genlmsg_mcast(skb, portid, group, flags);
1124}
1125EXPORT_SYMBOL(genlmsg_multicast_allns);
1126
1127void genl_notify(const struct genl_family *family, struct sk_buff *skb,
1128 struct genl_info *info, u32 group, gfp_t flags)
1129{
1130 struct net *net = genl_info_net(info);
1131 struct sock *sk = net->genl_sock;
1132 int report = 0;
1133
1134 if (info->nlhdr)
1135 report = nlmsg_report(info->nlhdr);
1136
1137 if (WARN_ON_ONCE(group >= family->n_mcgrps))
1138 return;
1139 group = family->mcgrp_offset + group;
1140 nlmsg_notify(sk, skb, info->snd_portid, group, report, flags);
1141}
1142EXPORT_SYMBOL(genl_notify);