aboutsummaryrefslogtreecommitdiff
path: root/net/netlink/genetlink.c
blob: 8903ef93db5b6be2be73d95f9f9ab421d41a7c5d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
/*
 * NETLINK      Generic Netlink Family
 *
 * 		Authors:	Jamal Hadi Salim
 * 				Thomas Graf <tgraf@suug.ch>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <linux/mutex.h>
#include <net/sock.h>
#include <net/genetlink.h>

struct sock *genl_sock = NULL;

static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */

static void genl_lock(void)
{
	mutex_lock(&genl_mutex);
}

static int genl_trylock(void)
{
	return !mutex_trylock(&genl_mutex);
}

static void genl_unlock(void)
{
	mutex_unlock(&genl_mutex);

	if (genl_sock && genl_sock->sk_receive_queue.qlen)
		genl_sock->sk_data_ready(genl_sock, 0);
}

#define GENL_FAM_TAB_SIZE	16
#define GENL_FAM_TAB_MASK	(GENL_FAM_TAB_SIZE - 1)

static struct list_head family_ht[GENL_FAM_TAB_SIZE];

static int genl_ctrl_event(int event, void *data);

static inline unsigned int genl_family_hash(unsigned int id)
{
	return id & GENL_FAM_TAB_MASK;
}

static inline struct list_head *genl_family_chain(unsigned int id)
{
	return &family_ht[genl_family_hash(id)];
}

static struct genl_family *genl_family_find_byid(unsigned int id)
{
	struct genl_family *f;

	list_for_each_entry(f, genl_family_chain(id), family_list)
		if (f->id == id)
			return f;

	return NULL;
}

static struct genl_family *genl_family_find_byname(char *name)
{
	struct genl_family *f;
	int i;

	for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
		list_for_each_entry(f, genl_family_chain(i), family_list)
			if (strcmp(f->name, name) == 0)
				return f;

	return NULL;
}

static struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
{
	struct genl_ops *ops;

	list_for_each_entry(ops, &family->ops_list, ops_list)
		if (ops->cmd == cmd)
			return ops;

	return NULL;
}

/* Of course we are going to have problems once we hit
 * 2^16 alive types, but that can only happen by year 2K
*/
static inline u16 genl_generate_id(void)
{
	static u16 id_gen_idx;
	int overflowed = 0;

	do {
		if (id_gen_idx == 0)
			id_gen_idx = GENL_MIN_ID;

		if (++id_gen_idx > GENL_MAX_ID) {
			if (!overflowed) {
				overflowed = 1;
				id_gen_idx = 0;
				continue;
			} else
				return 0;
		}

	} while (genl_family_find_byid(id_gen_idx));

	return id_gen_idx;
}

/**
 * genl_register_ops - register generic netlink operations
 * @family: generic netlink family
 * @ops: operations to be registered
 *
 * Registers the specified operations and assigns them to the specified
 * family. Either a doit or dumpit callback must be specified or the
 * operation will fail. Only one operation structure per command
 * identifier may be registered.
 *
 * See include/net/genetlink.h for more documenation on the operations
 * structure.
 *
 * Returns 0 on success or a negative error code.
 */
int genl_register_ops(struct genl_family *family, struct genl_ops *ops)
{
	int err = -EINVAL;

	if (ops->dumpit == NULL && ops->doit == NULL)
		goto errout;

	if (genl_get_cmd(ops->cmd, family)) {
		err = -EEXIST;
		goto errout;
	}

	genl_lock();
	list_add_tail(&ops->ops_list, &family->ops_list);
	genl_unlock();

	genl_ctrl_event(CTRL_CMD_NEWOPS, ops);
	err = 0;
errout:
	return err;
}

/**
 * genl_unregister_ops - unregister generic netlink operations
 * @family: generic netlink family
 * @ops: operations to be unregistered
 *
 * Unregisters the specified operations and unassigns them from the
 * specified family. The operation blocks until the current message
 * processing has finished and doesn't start again until the
 * unregister process has finished.
 *
 * Note: It is not necessary to unregister all operations before
 *       unregistering the family, unregistering the family will cause
 *       all assigned operations to be unregistered automatically.
 *
 * Returns 0 on success or a negative error code.
 */
int genl_unregister_ops(struct genl_family *family, struct genl_ops *ops)
{
	struct genl_ops *rc;

	genl_lock();
	list_for_each_entry(rc, &family->ops_list, ops_list) {
		if (rc == ops) {
			list_del(&ops->ops_list);
			genl_unlock();
			genl_ctrl_event(CTRL_CMD_DELOPS, ops);
			return 0;
		}
	}
	genl_unlock();

	return -ENOENT;
}

/**
 * genl_register_family - register a generic netlink family
 * @family: generic netlink family
 *
 * Registers the specified family after validating it first. Only one
 * family may be registered with the same family name or identifier.
 * The family id may equal GENL_ID_GENERATE causing an unique id to
 * be automatically generated and assigned.
 *
 * Return 0 on success or a negative error code.
 */
int genl_register_family(struct genl_family *family)
{
	int err = -EINVAL;

	if (family->id && family->id < GENL_MIN_ID)
		goto errout;

	if (family->id > GENL_MAX_ID)
		goto errout;

	INIT_LIST_HEAD(&family->ops_list);

	genl_lock();

	if (genl_family_find_byname(family->name)) {
		err = -EEXIST;
		goto errout_locked;
	}

	if (genl_family_find_byid(family->id)) {
		err = -EEXIST;
		goto errout_locked;
	}

	if (family->id == GENL_ID_GENERATE) {
		u16 newid = genl_generate_id();

		if (!newid) {
			err = -ENOMEM;
			goto errout_locked;
		}

		family->id = newid;
	}

	if (family->maxattr) {
		family->attrbuf = kmalloc((family->maxattr+1) *
					sizeof(struct nlattr *), GFP_KERNEL);
		if (family->attrbuf == NULL) {
			err = -ENOMEM;
			goto errout_locked;
		}
	} else
		family->attrbuf = NULL;

	list_add_tail(&family->family_list, genl_family_chain(family->id));
	genl_unlock();

	genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);

	return 0;

errout_locked:
	genl_unlock();
errout:
	return err;
}

/**
 * genl_unregister_family - unregister generic netlink family
 * @family: generic netlink family
 *
 * Unregisters the specified family.
 *
 * Returns 0 on success or a negative error code.
 */
int genl_unregister_family(struct genl_family *family)
{
	struct genl_family *rc;

	genl_lock();

	list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
		if (family->id != rc->id || strcmp(rc->name, family->name))
			continue;

		list_del(&rc->family_list);
		INIT_LIST_HEAD(&family->ops_list);
		genl_unlock();

		kfree(family->attrbuf);
		genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
		return 0;
	}

	genl_unlock();

	return -ENOENT;
}

static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
			       int *errp)
{
	struct genl_ops *ops;
	struct genl_family *family;
	struct genl_info info;
	struct genlmsghdr *hdr = nlmsg_data(nlh);
	int hdrlen, err = -EINVAL;

	if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
		goto ignore;

	if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
		goto ignore;

       	family = genl_family_find_byid(nlh->nlmsg_type);
	if (family == NULL) {
		err = -ENOENT;
		goto errout;
	}

	hdrlen = GENL_HDRLEN + family->hdrsize;
	if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
		goto errout;

	ops = genl_get_cmd(hdr->cmd, family);
	if (ops == NULL) {
		err = -EOPNOTSUPP;
		goto errout;
	}

	if ((ops->flags & GENL_ADMIN_PERM) && security_netlink_recv(skb, CAP_NET_ADMIN)) {
		err = -EPERM;
		goto errout;
	}

	if (nlh->nlmsg_flags & NLM_F_DUMP) {
		if (ops->dumpit == NULL) {
			err = -EOPNOTSUPP;
			goto errout;
		}

		*errp = err = netlink_dump_start(genl_sock, skb, nlh,
						 ops->dumpit, NULL);
		if (err == 0)
			skb_pull(skb, min(NLMSG_ALIGN(nlh->nlmsg_len),
					  skb->len));
		return -1;
	}

	if (ops->doit == NULL) {
		err = -EOPNOTSUPP;
		goto errout;
	}

	if (family->attrbuf) {
		err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr,
				  ops->policy);
		if (err < 0)
			goto errout;
	}

	info.snd_seq = nlh->nlmsg_seq;
	info.snd_pid = NETLINK_CB(skb).pid;
	info.nlhdr = nlh;
	info.genlhdr = nlmsg_data(nlh);
	info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
	info.attrs = family->attrbuf;

	*errp = err = ops->doit(skb, &info);
	return err;

ignore:
	return 0;

errout:
	*errp = err;
	return -1;
}

static void genl_rcv(struct sock *sk, int len)
{
	unsigned int qlen = 0;

	do {
		if (genl_trylock())
			return;
		netlink_run_queue(sk, &qlen, genl_rcv_msg);
		genl_unlock();
	} while (qlen && genl_sock && genl_sock->sk_receive_queue.qlen);
}

/**************************************************************************
 * Controller
 **************************************************************************/

static struct genl_family genl_ctrl = {
	.id = GENL_ID_CTRL,
	.name = "nlctrl",
	.version = 0x1,
	.maxattr = CTRL_ATTR_MAX,
};

static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
			  u32 flags, struct sk_buff *skb, u8 cmd)
{
	struct nlattr *nla_ops;
	struct genl_ops *ops;
	void *hdr;
	int idx = 1;

	hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
	if (hdr == NULL)
		return -1;

	NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, family->name);
	NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, family->id);
	NLA_PUT_U32(skb, CTRL_ATTR_VERSION, family->version);
	NLA_PUT_U32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize);
	NLA_PUT_U32(skb, CTRL_ATTR_MAXATTR, family->maxattr);

	nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
	if (nla_ops == NULL)
		goto nla_put_failure;

	list_for_each_entry(ops, &family->ops_list, ops_list) {
		struct nlattr *nest;

		nest = nla_nest_start(skb, idx++);
		if (nest == NULL)
			goto nla_put_failure;

		NLA_PUT_U32(skb, CTRL_ATTR_OP_ID, ops->cmd);
		NLA_PUT_U32(skb, CTRL_ATTR_OP_FLAGS, ops->flags);

		if (ops->policy)
			NLA_PUT_FLAG(skb, CTRL_ATTR_OP_POLICY);

		if (ops->doit)
			NLA_PUT_FLAG(skb, CTRL_ATTR_OP_DOIT);

		if (ops->dumpit)
			NLA_PUT_FLAG(skb, CTRL_ATTR_OP_DUMPIT);

		nla_nest_end(skb, nest);
	}

	nla_nest_end(skb, nla_ops);

	return genlmsg_end(skb, hdr);

nla_put_failure:
	return genlmsg_cancel(skb, hdr);
}

static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
{

	int i, n = 0;
	struct genl_family *rt;
	int chains_to_skip = cb->args[0];
	int fams_to_skip = cb->args[1];

	if (chains_to_skip != 0)
		genl_lock();

	for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
		if (i < chains_to_skip)
			continue;
		n = 0;
		list_for_each_entry(rt, genl_family_chain(i), family_list) {
			if (++n < fams_to_skip)
				continue;
			if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).pid,
					   cb->nlh->nlmsg_seq, NLM_F_MULTI,
					   skb, CTRL_CMD_NEWFAMILY) < 0)
				goto errout;
		}

		fams_to_skip = 0;
	}

errout:
	if (chains_to_skip != 0)
		genl_unlock();

	cb->args[0] = i;
	cb->args[1] = n;

	return skb->len;
}

static struct sk_buff *ctrl_build_msg(struct genl_family *family, u32 pid,
				      int seq, u8 cmd)
{
	struct sk_buff *skb;
	int err;

	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
	if (skb == NULL)
		return ERR_PTR(-ENOBUFS);

	err = ctrl_fill_info(family, pid, seq, 0, skb, cmd);
	if (err < 0) {
		nlmsg_free(skb);
		return ERR_PTR(err);
	}

	return skb;
}

static struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] __read_mostly = {
	[CTRL_ATTR_FAMILY_ID]	= { .type = NLA_U16 },
	[CTRL_ATTR_FAMILY_NAME]	= { .type = NLA_NUL_STRING,
				    .len = GENL_NAMSIZ - 1 },
};

static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
{
	struct sk_buff *msg;
	struct genl_family *res = NULL;
	int err = -EINVAL;

	if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
		u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
		res = genl_family_find_byid(id);
	}

	if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
		char *name;

		name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
		res = genl_family_find_byname(name);
	}

	if (res == NULL) {
		err = -ENOENT;
		goto errout;
	}

	msg = ctrl_build_msg(res, info->snd_pid, info->snd_seq,
			     CTRL_CMD_NEWFAMILY);
	if (IS_ERR(msg)) {
		err = PTR_ERR(msg);
		goto errout;
	}

	err = genlmsg_reply(msg, info);
errout:
	return err;
}

static int genl_ctrl_event(int event, void *data)
{
	struct sk_buff *msg;

	if (genl_sock == NULL)
		return 0;

	switch (event) {
	case CTRL_CMD_NEWFAMILY:
	case CTRL_CMD_DELFAMILY:
		msg = ctrl_build_msg(data, 0, 0, event);
		if (IS_ERR(msg))
			return PTR_ERR(msg);

		genlmsg_multicast(msg, 0, GENL_ID_CTRL, GFP_KERNEL);
		break;
	}

	return 0;
}

static struct genl_ops genl_ctrl_ops = {
	.cmd		= CTRL_CMD_GETFAMILY,
	.doit		= ctrl_getfamily,
	.dumpit		= ctrl_dumpfamily,
	.policy		= ctrl_policy,
};

static int __init genl_init(void)
{
	int i, err;

	for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
		INIT_LIST_HEAD(&family_ht[i]);

	err = genl_register_family(&genl_ctrl);
	if (err < 0)
		goto errout;

	err = genl_register_ops(&genl_ctrl, &genl_ctrl_ops);
	if (err < 0)
		goto errout_register;

	netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);
	genl_sock = netlink_kernel_create(NETLINK_GENERIC, GENL_MAX_ID,
					  genl_rcv, THIS_MODULE);
	if (genl_sock == NULL)
		panic("GENL: Cannot initialize generic netlink\n");

	return 0;

errout_register:
	genl_unregister_family(&genl_ctrl);
errout:
	panic("GENL: Cannot register controller: %d\n", err);
}

subsys_initcall(genl_init);

EXPORT_SYMBOL(genl_sock);
EXPORT_SYMBOL(genl_register_ops);
EXPORT_SYMBOL(genl_unregister_ops);
EXPORT_SYMBOL(genl_register_family);
EXPORT_SYMBOL(genl_unregister_family);