blob: 49bc2db7982b656096f219d670e4a74c344834a7 [file] [log] [blame]
Thomas Graf482a8522005-11-10 02:25:56 +01001/*
2 * NETLINK Generic Netlink Family
3 *
4 * Authors: Jamal Hadi Salim
5 * Thomas Graf <tgraf@suug.ch>
6 */
7
Thomas Graf482a8522005-11-10 02:25:56 +01008#include <linux/module.h>
9#include <linux/kernel.h>
10#include <linux/errno.h>
11#include <linux/types.h>
12#include <linux/socket.h>
13#include <linux/string.h>
14#include <linux/skbuff.h>
Ingo Molnar14cc3e22006-03-26 01:37:14 -080015#include <linux/mutex.h>
Thomas Graf482a8522005-11-10 02:25:56 +010016#include <net/sock.h>
17#include <net/genetlink.h>
18
19struct sock *genl_sock = NULL;
20
Ingo Molnar14cc3e22006-03-26 01:37:14 -080021static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
Thomas Graf482a8522005-11-10 02:25:56 +010022
23static void genl_lock(void)
24{
Ingo Molnar14cc3e22006-03-26 01:37:14 -080025 mutex_lock(&genl_mutex);
Thomas Graf482a8522005-11-10 02:25:56 +010026}
27
28static int genl_trylock(void)
29{
Ingo Molnar14cc3e22006-03-26 01:37:14 -080030 return !mutex_trylock(&genl_mutex);
Thomas Graf482a8522005-11-10 02:25:56 +010031}
32
33static void genl_unlock(void)
34{
Ingo Molnar14cc3e22006-03-26 01:37:14 -080035 mutex_unlock(&genl_mutex);
Thomas Graf482a8522005-11-10 02:25:56 +010036
37 if (genl_sock && genl_sock->sk_receive_queue.qlen)
38 genl_sock->sk_data_ready(genl_sock, 0);
39}
40
41#define GENL_FAM_TAB_SIZE 16
42#define GENL_FAM_TAB_MASK (GENL_FAM_TAB_SIZE - 1)
43
44static struct list_head family_ht[GENL_FAM_TAB_SIZE];
45
46static int genl_ctrl_event(int event, void *data);
47
48static inline unsigned int genl_family_hash(unsigned int id)
49{
50 return id & GENL_FAM_TAB_MASK;
51}
52
53static inline struct list_head *genl_family_chain(unsigned int id)
54{
55 return &family_ht[genl_family_hash(id)];
56}
57
58static struct genl_family *genl_family_find_byid(unsigned int id)
59{
60 struct genl_family *f;
61
62 list_for_each_entry(f, genl_family_chain(id), family_list)
63 if (f->id == id)
64 return f;
65
66 return NULL;
67}
68
69static struct genl_family *genl_family_find_byname(char *name)
70{
71 struct genl_family *f;
72 int i;
73
74 for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
75 list_for_each_entry(f, genl_family_chain(i), family_list)
76 if (strcmp(f->name, name) == 0)
77 return f;
78
79 return NULL;
80}
81
82static struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
83{
84 struct genl_ops *ops;
85
86 list_for_each_entry(ops, &family->ops_list, ops_list)
87 if (ops->cmd == cmd)
88 return ops;
89
90 return NULL;
91}
92
93/* Of course we are going to have problems once we hit
94 * 2^16 alive types, but that can only happen by year 2K
95*/
96static inline u16 genl_generate_id(void)
97{
98 static u16 id_gen_idx;
99 int overflowed = 0;
100
101 do {
102 if (id_gen_idx == 0)
103 id_gen_idx = GENL_MIN_ID;
104
105 if (++id_gen_idx > GENL_MAX_ID) {
106 if (!overflowed) {
107 overflowed = 1;
108 id_gen_idx = 0;
109 continue;
110 } else
111 return 0;
112 }
113
114 } while (genl_family_find_byid(id_gen_idx));
115
116 return id_gen_idx;
117}
118
119/**
120 * genl_register_ops - register generic netlink operations
121 * @family: generic netlink family
122 * @ops: operations to be registered
123 *
124 * Registers the specified operations and assigns them to the specified
125 * family. Either a doit or dumpit callback must be specified or the
126 * operation will fail. Only one operation structure per command
127 * identifier may be registered.
128 *
129 * See include/net/genetlink.h for more documenation on the operations
130 * structure.
131 *
132 * Returns 0 on success or a negative error code.
133 */
134int genl_register_ops(struct genl_family *family, struct genl_ops *ops)
135{
136 int err = -EINVAL;
137
138 if (ops->dumpit == NULL && ops->doit == NULL)
139 goto errout;
140
141 if (genl_get_cmd(ops->cmd, family)) {
142 err = -EEXIST;
143 goto errout;
144 }
145
146 genl_lock();
147 list_add_tail(&ops->ops_list, &family->ops_list);
148 genl_unlock();
149
150 genl_ctrl_event(CTRL_CMD_NEWOPS, ops);
151 err = 0;
152errout:
153 return err;
154}
155
156/**
157 * genl_unregister_ops - unregister generic netlink operations
158 * @family: generic netlink family
159 * @ops: operations to be unregistered
160 *
161 * Unregisters the specified operations and unassigns them from the
162 * specified family. The operation blocks until the current message
163 * processing has finished and doesn't start again until the
164 * unregister process has finished.
165 *
166 * Note: It is not necessary to unregister all operations before
167 * unregistering the family, unregistering the family will cause
168 * all assigned operations to be unregistered automatically.
169 *
170 * Returns 0 on success or a negative error code.
171 */
172int genl_unregister_ops(struct genl_family *family, struct genl_ops *ops)
173{
174 struct genl_ops *rc;
175
176 genl_lock();
177 list_for_each_entry(rc, &family->ops_list, ops_list) {
178 if (rc == ops) {
179 list_del(&ops->ops_list);
180 genl_unlock();
181 genl_ctrl_event(CTRL_CMD_DELOPS, ops);
182 return 0;
183 }
184 }
185 genl_unlock();
186
187 return -ENOENT;
188}
189
190/**
191 * genl_register_family - register a generic netlink family
192 * @family: generic netlink family
193 *
194 * Registers the specified family after validating it first. Only one
195 * family may be registered with the same family name or identifier.
196 * The family id may equal GENL_ID_GENERATE causing an unique id to
197 * be automatically generated and assigned.
198 *
199 * Return 0 on success or a negative error code.
200 */
201int genl_register_family(struct genl_family *family)
202{
203 int err = -EINVAL;
204
205 if (family->id && family->id < GENL_MIN_ID)
206 goto errout;
207
208 if (family->id > GENL_MAX_ID)
209 goto errout;
210
211 INIT_LIST_HEAD(&family->ops_list);
212
213 genl_lock();
214
215 if (genl_family_find_byname(family->name)) {
216 err = -EEXIST;
217 goto errout_locked;
218 }
219
220 if (genl_family_find_byid(family->id)) {
221 err = -EEXIST;
222 goto errout_locked;
223 }
224
Thomas Graf482a8522005-11-10 02:25:56 +0100225 if (family->id == GENL_ID_GENERATE) {
226 u16 newid = genl_generate_id();
227
228 if (!newid) {
229 err = -ENOMEM;
230 goto errout_locked;
231 }
232
233 family->id = newid;
234 }
235
236 if (family->maxattr) {
237 family->attrbuf = kmalloc((family->maxattr+1) *
238 sizeof(struct nlattr *), GFP_KERNEL);
239 if (family->attrbuf == NULL) {
240 err = -ENOMEM;
Jamal Hadi Salime200bd82006-02-13 15:51:24 -0800241 goto errout_locked;
Thomas Graf482a8522005-11-10 02:25:56 +0100242 }
243 } else
244 family->attrbuf = NULL;
245
246 list_add_tail(&family->family_list, genl_family_chain(family->id));
247 genl_unlock();
248
249 genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);
250
251 return 0;
252
253errout_locked:
254 genl_unlock();
255errout:
256 return err;
257}
258
259/**
260 * genl_unregister_family - unregister generic netlink family
261 * @family: generic netlink family
262 *
263 * Unregisters the specified family.
264 *
265 * Returns 0 on success or a negative error code.
266 */
267int genl_unregister_family(struct genl_family *family)
268{
269 struct genl_family *rc;
270
271 genl_lock();
272
273 list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
274 if (family->id != rc->id || strcmp(rc->name, family->name))
275 continue;
276
277 list_del(&rc->family_list);
278 INIT_LIST_HEAD(&family->ops_list);
279 genl_unlock();
280
Thomas Graf482a8522005-11-10 02:25:56 +0100281 kfree(family->attrbuf);
282 genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
283 return 0;
284 }
285
286 genl_unlock();
287
288 return -ENOENT;
289}
290
Jamal Hadi Salime200bd82006-02-13 15:51:24 -0800291static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
Thomas Graf482a8522005-11-10 02:25:56 +0100292 int *errp)
293{
294 struct genl_ops *ops;
295 struct genl_family *family;
296 struct genl_info info;
297 struct genlmsghdr *hdr = nlmsg_data(nlh);
298 int hdrlen, err = -EINVAL;
299
300 if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
301 goto ignore;
302
303 if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
304 goto ignore;
305
306 family = genl_family_find_byid(nlh->nlmsg_type);
307 if (family == NULL) {
308 err = -ENOENT;
309 goto errout;
310 }
311
312 hdrlen = GENL_HDRLEN + family->hdrsize;
313 if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
314 goto errout;
315
316 ops = genl_get_cmd(hdr->cmd, family);
317 if (ops == NULL) {
318 err = -EOPNOTSUPP;
319 goto errout;
320 }
321
Darrel Goeddelc7bdb542006-06-27 13:26:11 -0700322 if ((ops->flags & GENL_ADMIN_PERM) && security_netlink_recv(skb, CAP_NET_ADMIN)) {
Thomas Graf482a8522005-11-10 02:25:56 +0100323 err = -EPERM;
324 goto errout;
325 }
326
327 if (nlh->nlmsg_flags & NLM_F_DUMP) {
328 if (ops->dumpit == NULL) {
329 err = -EOPNOTSUPP;
330 goto errout;
331 }
332
333 *errp = err = netlink_dump_start(genl_sock, skb, nlh,
334 ops->dumpit, NULL);
335 if (err == 0)
336 skb_pull(skb, min(NLMSG_ALIGN(nlh->nlmsg_len),
337 skb->len));
338 return -1;
339 }
340
341 if (ops->doit == NULL) {
342 err = -EOPNOTSUPP;
343 goto errout;
344 }
345
346 if (family->attrbuf) {
347 err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr,
348 ops->policy);
349 if (err < 0)
350 goto errout;
351 }
352
353 info.snd_seq = nlh->nlmsg_seq;
354 info.snd_pid = NETLINK_CB(skb).pid;
355 info.nlhdr = nlh;
356 info.genlhdr = nlmsg_data(nlh);
357 info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
358 info.attrs = family->attrbuf;
359
360 *errp = err = ops->doit(skb, &info);
361 return err;
362
363ignore:
364 return 0;
365
366errout:
367 *errp = err;
368 return -1;
369}
370
371static void genl_rcv(struct sock *sk, int len)
372{
373 unsigned int qlen = 0;
374
375 do {
376 if (genl_trylock())
377 return;
Jamal Hadi Salime200bd82006-02-13 15:51:24 -0800378 netlink_run_queue(sk, &qlen, genl_rcv_msg);
Thomas Graf482a8522005-11-10 02:25:56 +0100379 genl_unlock();
380 } while (qlen && genl_sock && genl_sock->sk_receive_queue.qlen);
381}
382
383/**************************************************************************
384 * Controller
385 **************************************************************************/
386
387static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
388 u32 flags, struct sk_buff *skb, u8 cmd)
389{
Thomas Grafeb328112006-09-18 00:01:59 -0700390 struct nlattr *nla_ops;
391 struct genl_ops *ops;
Thomas Graf482a8522005-11-10 02:25:56 +0100392 void *hdr;
Thomas Grafeb328112006-09-18 00:01:59 -0700393 int idx = 1;
Thomas Graf482a8522005-11-10 02:25:56 +0100394
395 hdr = genlmsg_put(skb, pid, seq, GENL_ID_CTRL, 0, flags, cmd,
396 family->version);
397 if (hdr == NULL)
398 return -1;
399
400 NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, family->name);
401 NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, family->id);
Thomas Grafeb328112006-09-18 00:01:59 -0700402 NLA_PUT_U32(skb, CTRL_ATTR_VERSION, family->version);
403 NLA_PUT_U32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize);
404 NLA_PUT_U32(skb, CTRL_ATTR_MAXATTR, family->maxattr);
405
406 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
407 if (nla_ops == NULL)
408 goto nla_put_failure;
409
410 list_for_each_entry(ops, &family->ops_list, ops_list) {
411 struct nlattr *nest;
412
413 nest = nla_nest_start(skb, idx++);
414 if (nest == NULL)
415 goto nla_put_failure;
416
417 NLA_PUT_U32(skb, CTRL_ATTR_OP_ID, ops->cmd);
418 NLA_PUT_U32(skb, CTRL_ATTR_OP_FLAGS, ops->flags);
419
420 if (ops->policy)
421 NLA_PUT_FLAG(skb, CTRL_ATTR_OP_POLICY);
422
423 if (ops->doit)
424 NLA_PUT_FLAG(skb, CTRL_ATTR_OP_DOIT);
425
426 if (ops->dumpit)
427 NLA_PUT_FLAG(skb, CTRL_ATTR_OP_DUMPIT);
428
429 nla_nest_end(skb, nest);
430 }
431
432 nla_nest_end(skb, nla_ops);
Thomas Graf482a8522005-11-10 02:25:56 +0100433
434 return genlmsg_end(skb, hdr);
435
436nla_put_failure:
437 return genlmsg_cancel(skb, hdr);
438}
439
440static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
441{
442
443 int i, n = 0;
444 struct genl_family *rt;
445 int chains_to_skip = cb->args[0];
446 int fams_to_skip = cb->args[1];
447
Thomas Grafeb328112006-09-18 00:01:59 -0700448 if (chains_to_skip != 0)
449 genl_lock();
450
Thomas Graf482a8522005-11-10 02:25:56 +0100451 for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
452 if (i < chains_to_skip)
453 continue;
454 n = 0;
455 list_for_each_entry(rt, genl_family_chain(i), family_list) {
456 if (++n < fams_to_skip)
457 continue;
458 if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).pid,
459 cb->nlh->nlmsg_seq, NLM_F_MULTI,
460 skb, CTRL_CMD_NEWFAMILY) < 0)
461 goto errout;
462 }
463
464 fams_to_skip = 0;
465 }
466
467errout:
Thomas Grafeb328112006-09-18 00:01:59 -0700468 if (chains_to_skip != 0)
469 genl_unlock();
470
Thomas Graf482a8522005-11-10 02:25:56 +0100471 cb->args[0] = i;
472 cb->args[1] = n;
473
474 return skb->len;
475}
476
477static struct sk_buff *ctrl_build_msg(struct genl_family *family, u32 pid,
Per Lidenb461d2f2006-01-03 14:13:29 -0800478 int seq, u8 cmd)
Thomas Graf482a8522005-11-10 02:25:56 +0100479{
480 struct sk_buff *skb;
481 int err;
482
Thomas Graffe4944e2006-08-04 23:03:05 -0700483 skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
Thomas Graf482a8522005-11-10 02:25:56 +0100484 if (skb == NULL)
485 return ERR_PTR(-ENOBUFS);
486
487 err = ctrl_fill_info(family, pid, seq, 0, skb, cmd);
488 if (err < 0) {
489 nlmsg_free(skb);
490 return ERR_PTR(err);
491 }
492
493 return skb;
494}
495
496static struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] __read_mostly = {
497 [CTRL_ATTR_FAMILY_ID] = { .type = NLA_U16 },
Thomas Graf5176f912006-08-26 20:13:18 -0700498 [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
499 .len = GENL_NAMSIZ - 1 },
Thomas Graf482a8522005-11-10 02:25:56 +0100500};
501
502static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
503{
504 struct sk_buff *msg;
505 struct genl_family *res = NULL;
506 int err = -EINVAL;
507
508 if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
509 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
510 res = genl_family_find_byid(id);
511 }
512
513 if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
Thomas Graf5176f912006-08-26 20:13:18 -0700514 char *name;
Thomas Graf482a8522005-11-10 02:25:56 +0100515
Thomas Graf5176f912006-08-26 20:13:18 -0700516 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
Thomas Graf482a8522005-11-10 02:25:56 +0100517 res = genl_family_find_byname(name);
518 }
519
520 if (res == NULL) {
521 err = -ENOENT;
522 goto errout;
523 }
524
525 msg = ctrl_build_msg(res, info->snd_pid, info->snd_seq,
526 CTRL_CMD_NEWFAMILY);
527 if (IS_ERR(msg)) {
528 err = PTR_ERR(msg);
529 goto errout;
530 }
531
532 err = genlmsg_unicast(msg, info->snd_pid);
533errout:
534 return err;
535}
536
537static int genl_ctrl_event(int event, void *data)
538{
539 struct sk_buff *msg;
540
541 if (genl_sock == NULL)
542 return 0;
543
544 switch (event) {
545 case CTRL_CMD_NEWFAMILY:
546 case CTRL_CMD_DELFAMILY:
547 msg = ctrl_build_msg(data, 0, 0, event);
548 if (IS_ERR(msg))
549 return PTR_ERR(msg);
550
Thomas Grafd387f6a2006-08-15 00:31:06 -0700551 genlmsg_multicast(msg, 0, GENL_ID_CTRL, GFP_KERNEL);
Thomas Graf482a8522005-11-10 02:25:56 +0100552 break;
553 }
554
555 return 0;
556}
557
558static struct genl_ops genl_ctrl_ops = {
559 .cmd = CTRL_CMD_GETFAMILY,
560 .doit = ctrl_getfamily,
561 .dumpit = ctrl_dumpfamily,
562 .policy = ctrl_policy,
563};
564
565static struct genl_family genl_ctrl = {
566 .id = GENL_ID_CTRL,
567 .name = "nlctrl",
568 .version = 0x1,
569 .maxattr = CTRL_ATTR_MAX,
Thomas Graf482a8522005-11-10 02:25:56 +0100570};
571
572static int __init genl_init(void)
573{
574 int i, err;
575
576 for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
577 INIT_LIST_HEAD(&family_ht[i]);
578
579 err = genl_register_family(&genl_ctrl);
580 if (err < 0)
581 goto errout;
582
583 err = genl_register_ops(&genl_ctrl, &genl_ctrl_ops);
584 if (err < 0)
585 goto errout_register;
586
587 netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);
588 genl_sock = netlink_kernel_create(NETLINK_GENERIC, GENL_MAX_ID,
589 genl_rcv, THIS_MODULE);
Jamal Hadi Salime200bd82006-02-13 15:51:24 -0800590 if (genl_sock == NULL)
Thomas Graf482a8522005-11-10 02:25:56 +0100591 panic("GENL: Cannot initialize generic netlink\n");
Thomas Graf482a8522005-11-10 02:25:56 +0100592
593 return 0;
594
595errout_register:
596 genl_unregister_family(&genl_ctrl);
597errout:
598 panic("GENL: Cannot register controller: %d\n", err);
Thomas Graf482a8522005-11-10 02:25:56 +0100599}
600
601subsys_initcall(genl_init);
602
603EXPORT_SYMBOL(genl_sock);
604EXPORT_SYMBOL(genl_register_ops);
605EXPORT_SYMBOL(genl_unregister_ops);
606EXPORT_SYMBOL(genl_register_family);
607EXPORT_SYMBOL(genl_unregister_family);