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Linux 5.7.7
[linux/fpc-iii.git] / net / netlink / genetlink.c
blob9c1c27f3a08946f84af21e6559268a7e3d3ad729
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
25 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
26 static DECLARE_RWSEM(cb_lock);
27
28 atomic_t genl_sk_destructing_cnt = ATOMIC_INIT(0);
29 DECLARE_WAIT_QUEUE_HEAD(genl_sk_destructing_waitq);
30
31 void genl_lock(void)
32 {
33 mutex_lock(&genl_mutex);
34 }
35 EXPORT_SYMBOL(genl_lock);
36
37 void genl_unlock(void)
38 {
39 mutex_unlock(&genl_mutex);
40 }
41 EXPORT_SYMBOL(genl_unlock);
42
43 #ifdef CONFIG_LOCKDEP
44 bool lockdep_genl_is_held(void)
45 {
46 return lockdep_is_held(&genl_mutex);
47 }
48 EXPORT_SYMBOL(lockdep_genl_is_held);
49 #endif
50
51 static void genl_lock_all(void)
52 {
53 down_write(&cb_lock);
54 genl_lock();
55 }
56
57 static void genl_unlock_all(void)
58 {
59 genl_unlock();
60 up_write(&cb_lock);
61 }
62
63 static 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 */
83 static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) |
84 BIT(GENL_ID_VFS_DQUOT) |
85 BIT(GENL_ID_PMCRAID);
86 static unsigned long *mc_groups = &mc_group_start;
87 static unsigned long mc_groups_longs = 1;
88
89 static int genl_ctrl_event(int event, const struct genl_family *family,
90 const struct genl_multicast_group *grp,
91 int grp_id);
92
93 static const struct genl_family *genl_family_find_byid(unsigned int id)
94 {
95 return idr_find(&genl_fam_idr, id);
96 }
97
98 static 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
110 static 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
122 static 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
182 static struct genl_family genl_ctrl;
183
184 static 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
262 static 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
287 static 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 */
322 int 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_array(family->maxattr + 1,
356 sizeof(struct nlattr *),
357 GFP_KERNEL);
358 if (family->attrbuf == NULL) {
359 err = -ENOMEM;
360 goto errout_locked;
361 }
362 } else
363 family->attrbuf = NULL;
364
365 family->id = idr_alloc_cyclic(&genl_fam_idr, family,
366 start, end + 1, GFP_KERNEL);
367 if (family->id < 0) {
368 err = family->id;
369 goto errout_free;
370 }
371
372 err = genl_validate_assign_mc_groups(family);
373 if (err)
374 goto errout_remove;
375
376 genl_unlock_all();
377
378 /* send all events */
379 genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0);
380 for (i = 0; i < family->n_mcgrps; i++)
381 genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family,
382 &family->mcgrps[i], family->mcgrp_offset + i);
383
384 return 0;
385
386 errout_remove:
387 idr_remove(&genl_fam_idr, family->id);
388 errout_free:
389 kfree(family->attrbuf);
390 errout_locked:
391 genl_unlock_all();
392 return err;
393 }
394 EXPORT_SYMBOL(genl_register_family);
395
396 /**
397 * genl_unregister_family - unregister generic netlink family
398 * @family: generic netlink family
399 *
400 * Unregisters the specified family.
401 *
402 * Returns 0 on success or a negative error code.
403 */
404 int genl_unregister_family(const struct genl_family *family)
405 {
406 genl_lock_all();
407
408 if (!genl_family_find_byid(family->id)) {
409 genl_unlock_all();
410 return -ENOENT;
411 }
412
413 genl_unregister_mc_groups(family);
414
415 idr_remove(&genl_fam_idr, family->id);
416
417 up_write(&cb_lock);
418 wait_event(genl_sk_destructing_waitq,
419 atomic_read(&genl_sk_destructing_cnt) == 0);
420 genl_unlock();
421
422 kfree(family->attrbuf);
423
424 genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
425
426 return 0;
427 }
428 EXPORT_SYMBOL(genl_unregister_family);
429
430 /**
431 * genlmsg_put - Add generic netlink header to netlink message
432 * @skb: socket buffer holding the message
433 * @portid: netlink portid the message is addressed to
434 * @seq: sequence number (usually the one of the sender)
435 * @family: generic netlink family
436 * @flags: netlink message flags
437 * @cmd: generic netlink command
438 *
439 * Returns pointer to user specific header
440 */
441 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
442 const struct genl_family *family, int flags, u8 cmd)
443 {
444 struct nlmsghdr *nlh;
445 struct genlmsghdr *hdr;
446
447 nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
448 family->hdrsize, flags);
449 if (nlh == NULL)
450 return NULL;
451
452 hdr = nlmsg_data(nlh);
453 hdr->cmd = cmd;
454 hdr->version = family->version;
455 hdr->reserved = 0;
456
457 return (char *) hdr + GENL_HDRLEN;
458 }
459 EXPORT_SYMBOL(genlmsg_put);
460
461 static struct genl_dumpit_info *genl_dumpit_info_alloc(void)
462 {
463 return kmalloc(sizeof(struct genl_dumpit_info), GFP_KERNEL);
464 }
465
466 static void genl_dumpit_info_free(const struct genl_dumpit_info *info)
467 {
468 kfree(info);
469 }
470
471 static struct nlattr **
472 genl_family_rcv_msg_attrs_parse(const struct genl_family *family,
473 struct nlmsghdr *nlh,
474 struct netlink_ext_ack *extack,
475 const struct genl_ops *ops,
476 int hdrlen,
477 enum genl_validate_flags no_strict_flag)
478 {
479 enum netlink_validation validate = ops->validate & no_strict_flag ?
480 NL_VALIDATE_LIBERAL :
481 NL_VALIDATE_STRICT;
482 struct nlattr **attrbuf;
483 int err;
484
485 if (!family->maxattr)
486 return NULL;
487
488 if (family->parallel_ops) {
489 attrbuf = kmalloc_array(family->maxattr + 1,
490 sizeof(struct nlattr *), GFP_KERNEL);
491 if (!attrbuf)
492 return ERR_PTR(-ENOMEM);
493 } else {
494 attrbuf = family->attrbuf;
495 }
496
497 err = __nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
498 family->policy, validate, extack);
499 if (err) {
500 if (family->parallel_ops)
501 kfree(attrbuf);
502 return ERR_PTR(err);
503 }
504 return attrbuf;
505 }
506
507 static void genl_family_rcv_msg_attrs_free(const struct genl_family *family,
508 struct nlattr **attrbuf)
509 {
510 if (family->parallel_ops)
511 kfree(attrbuf);
512 }
513
514 struct genl_start_context {
515 const struct genl_family *family;
516 struct nlmsghdr *nlh;
517 struct netlink_ext_ack *extack;
518 const struct genl_ops *ops;
519 int hdrlen;
520 };
521
522 static int genl_start(struct netlink_callback *cb)
523 {
524 struct genl_start_context *ctx = cb->data;
525 const struct genl_ops *ops = ctx->ops;
526 struct genl_dumpit_info *info;
527 struct nlattr **attrs = NULL;
528 int rc = 0;
529
530 if (ops->validate & GENL_DONT_VALIDATE_DUMP)
531 goto no_attrs;
532
533 if (ctx->nlh->nlmsg_len < nlmsg_msg_size(ctx->hdrlen))
534 return -EINVAL;
535
536 attrs = genl_family_rcv_msg_attrs_parse(ctx->family, ctx->nlh, ctx->extack,
537 ops, ctx->hdrlen,
538 GENL_DONT_VALIDATE_DUMP_STRICT);
539 if (IS_ERR(attrs))
540 return PTR_ERR(attrs);
541
542 no_attrs:
543 info = genl_dumpit_info_alloc();
544 if (!info) {
545 genl_family_rcv_msg_attrs_free(ctx->family, attrs);
546 return -ENOMEM;
547 }
548 info->family = ctx->family;
549 info->ops = ops;
550 info->attrs = attrs;
551
552 cb->data = info;
553 if (ops->start) {
554 if (!ctx->family->parallel_ops)
555 genl_lock();
556 rc = ops->start(cb);
557 if (!ctx->family->parallel_ops)
558 genl_unlock();
559 }
560
561 if (rc) {
562 genl_family_rcv_msg_attrs_free(info->family, info->attrs);
563 genl_dumpit_info_free(info);
564 cb->data = NULL;
565 }
566 return rc;
567 }
568
569 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
570 {
571 const struct genl_ops *ops = genl_dumpit_info(cb)->ops;
572 int rc;
573
574 genl_lock();
575 rc = ops->dumpit(skb, cb);
576 genl_unlock();
577 return rc;
578 }
579
580 static int genl_lock_done(struct netlink_callback *cb)
581 {
582 const struct genl_dumpit_info *info = genl_dumpit_info(cb);
583 const struct genl_ops *ops = info->ops;
584 int rc = 0;
585
586 if (ops->done) {
587 genl_lock();
588 rc = ops->done(cb);
589 genl_unlock();
590 }
591 genl_family_rcv_msg_attrs_free(info->family, info->attrs);
592 genl_dumpit_info_free(info);
593 return rc;
594 }
595
596 static int genl_parallel_done(struct netlink_callback *cb)
597 {
598 const struct genl_dumpit_info *info = genl_dumpit_info(cb);
599 const struct genl_ops *ops = info->ops;
600 int rc = 0;
601
602 if (ops->done)
603 rc = ops->done(cb);
604 genl_family_rcv_msg_attrs_free(info->family, info->attrs);
605 genl_dumpit_info_free(info);
606 return rc;
607 }
608
609 static int genl_family_rcv_msg_dumpit(const struct genl_family *family,
610 struct sk_buff *skb,
611 struct nlmsghdr *nlh,
612 struct netlink_ext_ack *extack,
613 const struct genl_ops *ops,
614 int hdrlen, struct net *net)
615 {
616 struct genl_start_context ctx;
617 int err;
618
619 if (!ops->dumpit)
620 return -EOPNOTSUPP;
621
622 ctx.family = family;
623 ctx.nlh = nlh;
624 ctx.extack = extack;
625 ctx.ops = ops;
626 ctx.hdrlen = hdrlen;
627
628 if (!family->parallel_ops) {
629 struct netlink_dump_control c = {
630 .module = family->module,
631 .data = &ctx,
632 .start = genl_start,
633 .dump = genl_lock_dumpit,
634 .done = genl_lock_done,
635 };
636
637 genl_unlock();
638 err = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
639 genl_lock();
640 } else {
641 struct netlink_dump_control c = {
642 .module = family->module,
643 .data = &ctx,
644 .start = genl_start,
645 .dump = ops->dumpit,
646 .done = genl_parallel_done,
647 };
648
649 err = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
650 }
651
652 return err;
653 }
654
655 static int genl_family_rcv_msg_doit(const struct genl_family *family,
656 struct sk_buff *skb,
657 struct nlmsghdr *nlh,
658 struct netlink_ext_ack *extack,
659 const struct genl_ops *ops,
660 int hdrlen, struct net *net)
661 {
662 struct nlattr **attrbuf;
663 struct genl_info info;
664 int err;
665
666 if (!ops->doit)
667 return -EOPNOTSUPP;
668
669 attrbuf = genl_family_rcv_msg_attrs_parse(family, nlh, extack,
670 ops, hdrlen,
671 GENL_DONT_VALIDATE_STRICT);
672 if (IS_ERR(attrbuf))
673 return PTR_ERR(attrbuf);
674
675 info.snd_seq = nlh->nlmsg_seq;
676 info.snd_portid = NETLINK_CB(skb).portid;
677 info.nlhdr = nlh;
678 info.genlhdr = nlmsg_data(nlh);
679 info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
680 info.attrs = attrbuf;
681 info.extack = extack;
682 genl_info_net_set(&info, net);
683 memset(&info.user_ptr, 0, sizeof(info.user_ptr));
684
685 if (family->pre_doit) {
686 err = family->pre_doit(ops, skb, &info);
687 if (err)
688 goto out;
689 }
690
691 err = ops->doit(skb, &info);
692
693 if (family->post_doit)
694 family->post_doit(ops, skb, &info);
695
696 out:
697 genl_family_rcv_msg_attrs_free(family, attrbuf);
698
699 return err;
700 }
701
702 static int genl_family_rcv_msg(const struct genl_family *family,
703 struct sk_buff *skb,
704 struct nlmsghdr *nlh,
705 struct netlink_ext_ack *extack)
706 {
707 const struct genl_ops *ops;
708 struct net *net = sock_net(skb->sk);
709 struct genlmsghdr *hdr = nlmsg_data(nlh);
710 int hdrlen;
711
712 /* this family doesn't exist in this netns */
713 if (!family->netnsok && !net_eq(net, &init_net))
714 return -ENOENT;
715
716 hdrlen = GENL_HDRLEN + family->hdrsize;
717 if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
718 return -EINVAL;
719
720 ops = genl_get_cmd(hdr->cmd, family);
721 if (ops == NULL)
722 return -EOPNOTSUPP;
723
724 if ((ops->flags & GENL_ADMIN_PERM) &&
725 !netlink_capable(skb, CAP_NET_ADMIN))
726 return -EPERM;
727
728 if ((ops->flags & GENL_UNS_ADMIN_PERM) &&
729 !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
730 return -EPERM;
731
732 if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP)
733 return genl_family_rcv_msg_dumpit(family, skb, nlh, extack,
734 ops, hdrlen, net);
735 else
736 return genl_family_rcv_msg_doit(family, skb, nlh, extack,
737 ops, hdrlen, net);
738 }
739
740 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
741 struct netlink_ext_ack *extack)
742 {
743 const struct genl_family *family;
744 int err;
745
746 family = genl_family_find_byid(nlh->nlmsg_type);
747 if (family == NULL)
748 return -ENOENT;
749
750 if (!family->parallel_ops)
751 genl_lock();
752
753 err = genl_family_rcv_msg(family, skb, nlh, extack);
754
755 if (!family->parallel_ops)
756 genl_unlock();
757
758 return err;
759 }
760
761 static void genl_rcv(struct sk_buff *skb)
762 {
763 down_read(&cb_lock);
764 netlink_rcv_skb(skb, &genl_rcv_msg);
765 up_read(&cb_lock);
766 }
767
768 /**************************************************************************
769 * Controller
770 **************************************************************************/
771
772 static struct genl_family genl_ctrl;
773
774 static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
775 u32 flags, struct sk_buff *skb, u8 cmd)
776 {
777 void *hdr;
778
779 hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
780 if (hdr == NULL)
781 return -1;
782
783 if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
784 nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
785 nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
786 nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
787 nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
788 goto nla_put_failure;
789
790 if (family->n_ops) {
791 struct nlattr *nla_ops;
792 int i;
793
794 nla_ops = nla_nest_start_noflag(skb, CTRL_ATTR_OPS);
795 if (nla_ops == NULL)
796 goto nla_put_failure;
797
798 for (i = 0; i < family->n_ops; i++) {
799 struct nlattr *nest;
800 const struct genl_ops *ops = &family->ops[i];
801 u32 op_flags = ops->flags;
802
803 if (ops->dumpit)
804 op_flags |= GENL_CMD_CAP_DUMP;
805 if (ops->doit)
806 op_flags |= GENL_CMD_CAP_DO;
807 if (family->policy)
808 op_flags |= GENL_CMD_CAP_HASPOL;
809
810 nest = nla_nest_start_noflag(skb, i + 1);
811 if (nest == NULL)
812 goto nla_put_failure;
813
814 if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
815 nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
816 goto nla_put_failure;
817
818 nla_nest_end(skb, nest);
819 }
820
821 nla_nest_end(skb, nla_ops);
822 }
823
824 if (family->n_mcgrps) {
825 struct nlattr *nla_grps;
826 int i;
827
828 nla_grps = nla_nest_start_noflag(skb, CTRL_ATTR_MCAST_GROUPS);
829 if (nla_grps == NULL)
830 goto nla_put_failure;
831
832 for (i = 0; i < family->n_mcgrps; i++) {
833 struct nlattr *nest;
834 const struct genl_multicast_group *grp;
835
836 grp = &family->mcgrps[i];
837
838 nest = nla_nest_start_noflag(skb, i + 1);
839 if (nest == NULL)
840 goto nla_put_failure;
841
842 if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
843 family->mcgrp_offset + i) ||
844 nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
845 grp->name))
846 goto nla_put_failure;
847
848 nla_nest_end(skb, nest);
849 }
850 nla_nest_end(skb, nla_grps);
851 }
852
853 genlmsg_end(skb, hdr);
854 return 0;
855
856 nla_put_failure:
857 genlmsg_cancel(skb, hdr);
858 return -EMSGSIZE;
859 }
860
861 static int ctrl_fill_mcgrp_info(const struct genl_family *family,
862 const struct genl_multicast_group *grp,
863 int grp_id, u32 portid, u32 seq, u32 flags,
864 struct sk_buff *skb, u8 cmd)
865 {
866 void *hdr;
867 struct nlattr *nla_grps;
868 struct nlattr *nest;
869
870 hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
871 if (hdr == NULL)
872 return -1;
873
874 if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
875 nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
876 goto nla_put_failure;
877
878 nla_grps = nla_nest_start_noflag(skb, CTRL_ATTR_MCAST_GROUPS);
879 if (nla_grps == NULL)
880 goto nla_put_failure;
881
882 nest = nla_nest_start_noflag(skb, 1);
883 if (nest == NULL)
884 goto nla_put_failure;
885
886 if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
887 nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
888 grp->name))
889 goto nla_put_failure;
890
891 nla_nest_end(skb, nest);
892 nla_nest_end(skb, nla_grps);
893
894 genlmsg_end(skb, hdr);
895 return 0;
896
897 nla_put_failure:
898 genlmsg_cancel(skb, hdr);
899 return -EMSGSIZE;
900 }
901
902 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
903 {
904 int n = 0;
905 struct genl_family *rt;
906 struct net *net = sock_net(skb->sk);
907 int fams_to_skip = cb->args[0];
908 unsigned int id;
909
910 idr_for_each_entry(&genl_fam_idr, rt, id) {
911 if (!rt->netnsok && !net_eq(net, &init_net))
912 continue;
913
914 if (n++ < fams_to_skip)
915 continue;
916
917 if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
918 cb->nlh->nlmsg_seq, NLM_F_MULTI,
919 skb, CTRL_CMD_NEWFAMILY) < 0) {
920 n--;
921 break;
922 }
923 }
924
925 cb->args[0] = n;
926 return skb->len;
927 }
928
929 static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family,
930 u32 portid, int seq, u8 cmd)
931 {
932 struct sk_buff *skb;
933 int err;
934
935 skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
936 if (skb == NULL)
937 return ERR_PTR(-ENOBUFS);
938
939 err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
940 if (err < 0) {
941 nlmsg_free(skb);
942 return ERR_PTR(err);
943 }
944
945 return skb;
946 }
947
948 static struct sk_buff *
949 ctrl_build_mcgrp_msg(const struct genl_family *family,
950 const struct genl_multicast_group *grp,
951 int grp_id, u32 portid, int seq, u8 cmd)
952 {
953 struct sk_buff *skb;
954 int err;
955
956 skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
957 if (skb == NULL)
958 return ERR_PTR(-ENOBUFS);
959
960 err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
961 seq, 0, skb, cmd);
962 if (err < 0) {
963 nlmsg_free(skb);
964 return ERR_PTR(err);
965 }
966
967 return skb;
968 }
969
970 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
971 [CTRL_ATTR_FAMILY_ID] = { .type = NLA_U16 },
972 [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
973 .len = GENL_NAMSIZ - 1 },
974 };
975
976 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
977 {
978 struct sk_buff *msg;
979 const struct genl_family *res = NULL;
980 int err = -EINVAL;
981
982 if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
983 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
984 res = genl_family_find_byid(id);
985 err = -ENOENT;
986 }
987
988 if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
989 char *name;
990
991 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
992 res = genl_family_find_byname(name);
993 #ifdef CONFIG_MODULES
994 if (res == NULL) {
995 genl_unlock();
996 up_read(&cb_lock);
997 request_module("net-pf-%d-proto-%d-family-%s",
998 PF_NETLINK, NETLINK_GENERIC, name);
999 down_read(&cb_lock);
1000 genl_lock();
1001 res = genl_family_find_byname(name);
1002 }
1003 #endif
1004 err = -ENOENT;
1005 }
1006
1007 if (res == NULL)
1008 return err;
1009
1010 if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
1011 /* family doesn't exist here */
1012 return -ENOENT;
1013 }
1014
1015 msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
1016 CTRL_CMD_NEWFAMILY);
1017 if (IS_ERR(msg))
1018 return PTR_ERR(msg);
1019
1020 return genlmsg_reply(msg, info);
1021 }
1022
1023 static int genl_ctrl_event(int event, const struct genl_family *family,
1024 const struct genl_multicast_group *grp,
1025 int grp_id)
1026 {
1027 struct sk_buff *msg;
1028
1029 /* genl is still initialising */
1030 if (!init_net.genl_sock)
1031 return 0;
1032
1033 switch (event) {
1034 case CTRL_CMD_NEWFAMILY:
1035 case CTRL_CMD_DELFAMILY:
1036 WARN_ON(grp);
1037 msg = ctrl_build_family_msg(family, 0, 0, event);
1038 break;
1039 case CTRL_CMD_NEWMCAST_GRP:
1040 case CTRL_CMD_DELMCAST_GRP:
1041 BUG_ON(!grp);
1042 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
1043 break;
1044 default:
1045 return -EINVAL;
1046 }
1047
1048 if (IS_ERR(msg))
1049 return PTR_ERR(msg);
1050
1051 if (!family->netnsok) {
1052 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
1053 0, GFP_KERNEL);
1054 } else {
1055 rcu_read_lock();
1056 genlmsg_multicast_allns(&genl_ctrl, msg, 0,
1057 0, GFP_ATOMIC);
1058 rcu_read_unlock();
1059 }
1060
1061 return 0;
1062 }
1063
1064 static const struct genl_ops genl_ctrl_ops[] = {
1065 {
1066 .cmd = CTRL_CMD_GETFAMILY,
1067 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
1068 .doit = ctrl_getfamily,
1069 .dumpit = ctrl_dumpfamily,
1070 },
1071 };
1072
1073 static const struct genl_multicast_group genl_ctrl_groups[] = {
1074 { .name = "notify", },
1075 };
1076
1077 static struct genl_family genl_ctrl __ro_after_init = {
1078 .module = THIS_MODULE,
1079 .ops = genl_ctrl_ops,
1080 .n_ops = ARRAY_SIZE(genl_ctrl_ops),
1081 .mcgrps = genl_ctrl_groups,
1082 .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups),
1083 .id = GENL_ID_CTRL,
1084 .name = "nlctrl",
1085 .version = 0x2,
1086 .maxattr = CTRL_ATTR_MAX,
1087 .policy = ctrl_policy,
1088 .netnsok = true,
1089 };
1090
1091 static int genl_bind(struct net *net, int group)
1092 {
1093 struct genl_family *f;
1094 int err = -ENOENT;
1095 unsigned int id;
1096
1097 down_read(&cb_lock);
1098
1099 idr_for_each_entry(&genl_fam_idr, f, id) {
1100 if (group >= f->mcgrp_offset &&
1101 group < f->mcgrp_offset + f->n_mcgrps) {
1102 int fam_grp = group - f->mcgrp_offset;
1103
1104 if (!f->netnsok && net != &init_net)
1105 err = -ENOENT;
1106 else if (f->mcast_bind)
1107 err = f->mcast_bind(net, fam_grp);
1108 else
1109 err = 0;
1110 break;
1111 }
1112 }
1113 up_read(&cb_lock);
1114
1115 return err;
1116 }
1117
1118 static void genl_unbind(struct net *net, int group)
1119 {
1120 struct genl_family *f;
1121 unsigned int id;
1122
1123 down_read(&cb_lock);
1124
1125 idr_for_each_entry(&genl_fam_idr, f, id) {
1126 if (group >= f->mcgrp_offset &&
1127 group < f->mcgrp_offset + f->n_mcgrps) {
1128 int fam_grp = group - f->mcgrp_offset;
1129
1130 if (f->mcast_unbind)
1131 f->mcast_unbind(net, fam_grp);
1132 break;
1133 }
1134 }
1135 up_read(&cb_lock);
1136 }
1137
1138 static int __net_init genl_pernet_init(struct net *net)
1139 {
1140 struct netlink_kernel_cfg cfg = {
1141 .input = genl_rcv,
1142 .flags = NL_CFG_F_NONROOT_RECV,
1143 .bind = genl_bind,
1144 .unbind = genl_unbind,
1145 };
1146
1147 /* we'll bump the group number right afterwards */
1148 net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
1149
1150 if (!net->genl_sock && net_eq(net, &init_net))
1151 panic("GENL: Cannot initialize generic netlink\n");
1152
1153 if (!net->genl_sock)
1154 return -ENOMEM;
1155
1156 return 0;
1157 }
1158
1159 static void __net_exit genl_pernet_exit(struct net *net)
1160 {
1161 netlink_kernel_release(net->genl_sock);
1162 net->genl_sock = NULL;
1163 }
1164
1165 static struct pernet_operations genl_pernet_ops = {
1166 .init = genl_pernet_init,
1167 .exit = genl_pernet_exit,
1168 };
1169
1170 static int __init genl_init(void)
1171 {
1172 int err;
1173
1174 err = genl_register_family(&genl_ctrl);
1175 if (err < 0)
1176 goto problem;
1177
1178 err = register_pernet_subsys(&genl_pernet_ops);
1179 if (err)
1180 goto problem;
1181
1182 return 0;
1183
1184 problem:
1185 panic("GENL: Cannot register controller: %d\n", err);
1186 }
1187
1188 subsys_initcall(genl_init);
1189
1190 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
1191 gfp_t flags)
1192 {
1193 struct sk_buff *tmp;
1194 struct net *net, *prev = NULL;
1195 bool delivered = false;
1196 int err;
1197
1198 for_each_net_rcu(net) {
1199 if (prev) {
1200 tmp = skb_clone(skb, flags);
1201 if (!tmp) {
1202 err = -ENOMEM;
1203 goto error;
1204 }
1205 err = nlmsg_multicast(prev->genl_sock, tmp,
1206 portid, group, flags);
1207 if (!err)
1208 delivered = true;
1209 else if (err != -ESRCH)
1210 goto error;
1211 }
1212
1213 prev = net;
1214 }
1215
1216 err = nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1217 if (!err)
1218 delivered = true;
1219 else if (err != -ESRCH)
1220 return err;
1221 return delivered ? 0 : -ESRCH;
1222 error:
1223 kfree_skb(skb);
1224 return err;
1225 }
1226
1227 int genlmsg_multicast_allns(const struct genl_family *family,
1228 struct sk_buff *skb, u32 portid,
1229 unsigned int group, gfp_t flags)
1230 {
1231 if (WARN_ON_ONCE(group >= family->n_mcgrps))
1232 return -EINVAL;
1233 group = family->mcgrp_offset + group;
1234 return genlmsg_mcast(skb, portid, group, flags);
1235 }
1236 EXPORT_SYMBOL(genlmsg_multicast_allns);
1237
1238 void genl_notify(const struct genl_family *family, struct sk_buff *skb,
1239 struct genl_info *info, u32 group, gfp_t flags)
1240 {
1241 struct net *net = genl_info_net(info);
1242 struct sock *sk = net->genl_sock;
1243 int report = 0;
1244
1245 if (info->nlhdr)
1246 report = nlmsg_report(info->nlhdr);
1247
1248 if (WARN_ON_ONCE(group >= family->n_mcgrps))
1249 return;
1250 group = family->mcgrp_offset + group;
1251 nlmsg_notify(sk, skb, info->snd_portid, group, report, flags);
1252 }
1253 EXPORT_SYMBOL(genl_notify);
Linux with added FPC-III support