Merge branch 'mv-merge'
[linux-2.6] / net / netlink / genetlink.c
1 /*
2  * NETLINK      Generic Netlink Family
3  *
4  *              Authors:        Jamal Hadi Salim
5  *                              Thomas Graf <tgraf@suug.ch>
6  */
7
8 #include <linux/config.h>
9 #include <linux/module.h>
10 #include <linux/kernel.h>
11 #include <linux/errno.h>
12 #include <linux/types.h>
13 #include <linux/socket.h>
14 #include <linux/string.h>
15 #include <linux/skbuff.h>
16 #include <linux/mutex.h>
17 #include <net/sock.h>
18 #include <net/genetlink.h>
19
20 struct sock *genl_sock = NULL;
21
22 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
23
24 static void genl_lock(void)
25 {
26         mutex_lock(&genl_mutex);
27 }
28
29 static int genl_trylock(void)
30 {
31         return !mutex_trylock(&genl_mutex);
32 }
33
34 static void genl_unlock(void)
35 {
36         mutex_unlock(&genl_mutex);
37
38         if (genl_sock && genl_sock->sk_receive_queue.qlen)
39                 genl_sock->sk_data_ready(genl_sock, 0);
40 }
41
42 #define GENL_FAM_TAB_SIZE       16
43 #define GENL_FAM_TAB_MASK       (GENL_FAM_TAB_SIZE - 1)
44
45 static struct list_head family_ht[GENL_FAM_TAB_SIZE];
46
47 static int genl_ctrl_event(int event, void *data);
48
49 static inline unsigned int genl_family_hash(unsigned int id)
50 {
51         return id & GENL_FAM_TAB_MASK;
52 }
53
54 static inline struct list_head *genl_family_chain(unsigned int id)
55 {
56         return &family_ht[genl_family_hash(id)];
57 }
58
59 static struct genl_family *genl_family_find_byid(unsigned int id)
60 {
61         struct genl_family *f;
62
63         list_for_each_entry(f, genl_family_chain(id), family_list)
64                 if (f->id == id)
65                         return f;
66
67         return NULL;
68 }
69
70 static struct genl_family *genl_family_find_byname(char *name)
71 {
72         struct genl_family *f;
73         int i;
74
75         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
76                 list_for_each_entry(f, genl_family_chain(i), family_list)
77                         if (strcmp(f->name, name) == 0)
78                                 return f;
79
80         return NULL;
81 }
82
83 static struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
84 {
85         struct genl_ops *ops;
86
87         list_for_each_entry(ops, &family->ops_list, ops_list)
88                 if (ops->cmd == cmd)
89                         return ops;
90
91         return NULL;
92 }
93
94 /* Of course we are going to have problems once we hit
95  * 2^16 alive types, but that can only happen by year 2K
96 */
97 static inline u16 genl_generate_id(void)
98 {
99         static u16 id_gen_idx;
100         int overflowed = 0;
101
102         do {
103                 if (id_gen_idx == 0)
104                         id_gen_idx = GENL_MIN_ID;
105
106                 if (++id_gen_idx > GENL_MAX_ID) {
107                         if (!overflowed) {
108                                 overflowed = 1;
109                                 id_gen_idx = 0;
110                                 continue;
111                         } else
112                                 return 0;
113                 }
114
115         } while (genl_family_find_byid(id_gen_idx));
116
117         return id_gen_idx;
118 }
119
120 /**
121  * genl_register_ops - register generic netlink operations
122  * @family: generic netlink family
123  * @ops: operations to be registered
124  *
125  * Registers the specified operations and assigns them to the specified
126  * family. Either a doit or dumpit callback must be specified or the
127  * operation will fail. Only one operation structure per command
128  * identifier may be registered.
129  *
130  * See include/net/genetlink.h for more documenation on the operations
131  * structure.
132  *
133  * Returns 0 on success or a negative error code.
134  */
135 int genl_register_ops(struct genl_family *family, struct genl_ops *ops)
136 {
137         int err = -EINVAL;
138
139         if (ops->dumpit == NULL && ops->doit == NULL)
140                 goto errout;
141
142         if (genl_get_cmd(ops->cmd, family)) {
143                 err = -EEXIST;
144                 goto errout;
145         }
146
147         genl_lock();
148         list_add_tail(&ops->ops_list, &family->ops_list);
149         genl_unlock();
150
151         genl_ctrl_event(CTRL_CMD_NEWOPS, ops);
152         err = 0;
153 errout:
154         return err;
155 }
156
157 /**
158  * genl_unregister_ops - unregister generic netlink operations
159  * @family: generic netlink family
160  * @ops: operations to be unregistered
161  *
162  * Unregisters the specified operations and unassigns them from the
163  * specified family. The operation blocks until the current message
164  * processing has finished and doesn't start again until the
165  * unregister process has finished.
166  *
167  * Note: It is not necessary to unregister all operations before
168  *       unregistering the family, unregistering the family will cause
169  *       all assigned operations to be unregistered automatically.
170  *
171  * Returns 0 on success or a negative error code.
172  */
173 int genl_unregister_ops(struct genl_family *family, struct genl_ops *ops)
174 {
175         struct genl_ops *rc;
176
177         genl_lock();
178         list_for_each_entry(rc, &family->ops_list, ops_list) {
179                 if (rc == ops) {
180                         list_del(&ops->ops_list);
181                         genl_unlock();
182                         genl_ctrl_event(CTRL_CMD_DELOPS, ops);
183                         return 0;
184                 }
185         }
186         genl_unlock();
187
188         return -ENOENT;
189 }
190
191 /**
192  * genl_register_family - register a generic netlink family
193  * @family: generic netlink family
194  *
195  * Registers the specified family after validating it first. Only one
196  * family may be registered with the same family name or identifier.
197  * The family id may equal GENL_ID_GENERATE causing an unique id to
198  * be automatically generated and assigned.
199  *
200  * Return 0 on success or a negative error code.
201  */
202 int genl_register_family(struct genl_family *family)
203 {
204         int err = -EINVAL;
205
206         if (family->id && family->id < GENL_MIN_ID)
207                 goto errout;
208
209         if (family->id > GENL_MAX_ID)
210                 goto errout;
211
212         INIT_LIST_HEAD(&family->ops_list);
213
214         genl_lock();
215
216         if (genl_family_find_byname(family->name)) {
217                 err = -EEXIST;
218                 goto errout_locked;
219         }
220
221         if (genl_family_find_byid(family->id)) {
222                 err = -EEXIST;
223                 goto errout_locked;
224         }
225
226         if (family->id == GENL_ID_GENERATE) {
227                 u16 newid = genl_generate_id();
228
229                 if (!newid) {
230                         err = -ENOMEM;
231                         goto errout_locked;
232                 }
233
234                 family->id = newid;
235         }
236
237         if (family->maxattr) {
238                 family->attrbuf = kmalloc((family->maxattr+1) *
239                                         sizeof(struct nlattr *), GFP_KERNEL);
240                 if (family->attrbuf == NULL) {
241                         err = -ENOMEM;
242                         goto errout_locked;
243                 }
244         } else
245                 family->attrbuf = NULL;
246
247         list_add_tail(&family->family_list, genl_family_chain(family->id));
248         genl_unlock();
249
250         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);
251
252         return 0;
253
254 errout_locked:
255         genl_unlock();
256 errout:
257         return err;
258 }
259
260 /**
261  * genl_unregister_family - unregister generic netlink family
262  * @family: generic netlink family
263  *
264  * Unregisters the specified family.
265  *
266  * Returns 0 on success or a negative error code.
267  */
268 int genl_unregister_family(struct genl_family *family)
269 {
270         struct genl_family *rc;
271
272         genl_lock();
273
274         list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
275                 if (family->id != rc->id || strcmp(rc->name, family->name))
276                         continue;
277
278                 list_del(&rc->family_list);
279                 INIT_LIST_HEAD(&family->ops_list);
280                 genl_unlock();
281
282                 kfree(family->attrbuf);
283                 genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
284                 return 0;
285         }
286
287         genl_unlock();
288
289         return -ENOENT;
290 }
291
292 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
293                                int *errp)
294 {
295         struct genl_ops *ops;
296         struct genl_family *family;
297         struct genl_info info;
298         struct genlmsghdr *hdr = nlmsg_data(nlh);
299         int hdrlen, err = -EINVAL;
300
301         if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
302                 goto ignore;
303
304         if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
305                 goto ignore;
306
307         family = genl_family_find_byid(nlh->nlmsg_type);
308         if (family == NULL) {
309                 err = -ENOENT;
310                 goto errout;
311         }
312
313         hdrlen = GENL_HDRLEN + family->hdrsize;
314         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
315                 goto errout;
316
317         ops = genl_get_cmd(hdr->cmd, family);
318         if (ops == NULL) {
319                 err = -EOPNOTSUPP;
320                 goto errout;
321         }
322
323         if ((ops->flags & GENL_ADMIN_PERM) && security_netlink_recv(skb)) {
324                 err = -EPERM;
325                 goto errout;
326         }
327
328         if (nlh->nlmsg_flags & NLM_F_DUMP) {
329                 if (ops->dumpit == NULL) {
330                         err = -EOPNOTSUPP;
331                         goto errout;
332                 }
333
334                 *errp = err = netlink_dump_start(genl_sock, skb, nlh,
335                                                  ops->dumpit, NULL);
336                 if (err == 0)
337                         skb_pull(skb, min(NLMSG_ALIGN(nlh->nlmsg_len),
338                                           skb->len));
339                 return -1;
340         }
341
342         if (ops->doit == NULL) {
343                 err = -EOPNOTSUPP;
344                 goto errout;
345         }
346
347         if (family->attrbuf) {
348                 err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr,
349                                   ops->policy);
350                 if (err < 0)
351                         goto errout;
352         }
353
354         info.snd_seq = nlh->nlmsg_seq;
355         info.snd_pid = NETLINK_CB(skb).pid;
356         info.nlhdr = nlh;
357         info.genlhdr = nlmsg_data(nlh);
358         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
359         info.attrs = family->attrbuf;
360
361         *errp = err = ops->doit(skb, &info);
362         return err;
363
364 ignore:
365         return 0;
366
367 errout:
368         *errp = err;
369         return -1;
370 }
371
372 static void genl_rcv(struct sock *sk, int len)
373 {
374         unsigned int qlen = 0;
375
376         do {
377                 if (genl_trylock())
378                         return;
379                 netlink_run_queue(sk, &qlen, genl_rcv_msg);
380                 genl_unlock();
381         } while (qlen && genl_sock && genl_sock->sk_receive_queue.qlen);
382 }
383
384 /**************************************************************************
385  * Controller
386  **************************************************************************/
387
388 static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
389                           u32 flags, struct sk_buff *skb, u8 cmd)
390 {
391         void *hdr;
392
393         hdr = genlmsg_put(skb, pid, seq, GENL_ID_CTRL, 0, flags, cmd,
394                           family->version);
395         if (hdr == NULL)
396                 return -1;
397
398         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, family->name);
399         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, family->id);
400
401         return genlmsg_end(skb, hdr);
402
403 nla_put_failure:
404         return genlmsg_cancel(skb, hdr);
405 }
406
407 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
408 {
409
410         int i, n = 0;
411         struct genl_family *rt;
412         int chains_to_skip = cb->args[0];
413         int fams_to_skip = cb->args[1];
414
415         for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
416                 if (i < chains_to_skip)
417                         continue;
418                 n = 0;
419                 list_for_each_entry(rt, genl_family_chain(i), family_list) {
420                         if (++n < fams_to_skip)
421                                 continue;
422                         if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).pid,
423                                            cb->nlh->nlmsg_seq, NLM_F_MULTI,
424                                            skb, CTRL_CMD_NEWFAMILY) < 0)
425                                 goto errout;
426                 }
427
428                 fams_to_skip = 0;
429         }
430
431 errout:
432         cb->args[0] = i;
433         cb->args[1] = n;
434
435         return skb->len;
436 }
437
438 static struct sk_buff *ctrl_build_msg(struct genl_family *family, u32 pid,
439                                       int seq, u8 cmd)
440 {
441         struct sk_buff *skb;
442         int err;
443
444         skb = nlmsg_new(NLMSG_GOODSIZE);
445         if (skb == NULL)
446                 return ERR_PTR(-ENOBUFS);
447
448         err = ctrl_fill_info(family, pid, seq, 0, skb, cmd);
449         if (err < 0) {
450                 nlmsg_free(skb);
451                 return ERR_PTR(err);
452         }
453
454         return skb;
455 }
456
457 static struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] __read_mostly = {
458         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
459         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_STRING },
460 };
461
462 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
463 {
464         struct sk_buff *msg;
465         struct genl_family *res = NULL;
466         int err = -EINVAL;
467
468         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
469                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
470                 res = genl_family_find_byid(id);
471         }
472
473         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
474                 char name[GENL_NAMSIZ];
475
476                 if (nla_strlcpy(name, info->attrs[CTRL_ATTR_FAMILY_NAME],
477                                 GENL_NAMSIZ) >= GENL_NAMSIZ)
478                         goto errout;
479
480                 res = genl_family_find_byname(name);
481         }
482
483         if (res == NULL) {
484                 err = -ENOENT;
485                 goto errout;
486         }
487
488         msg = ctrl_build_msg(res, info->snd_pid, info->snd_seq,
489                              CTRL_CMD_NEWFAMILY);
490         if (IS_ERR(msg)) {
491                 err = PTR_ERR(msg);
492                 goto errout;
493         }
494
495         err = genlmsg_unicast(msg, info->snd_pid);
496 errout:
497         return err;
498 }
499
500 static int genl_ctrl_event(int event, void *data)
501 {
502         struct sk_buff *msg;
503
504         if (genl_sock == NULL)
505                 return 0;
506
507         switch (event) {
508         case CTRL_CMD_NEWFAMILY:
509         case CTRL_CMD_DELFAMILY:
510                 msg = ctrl_build_msg(data, 0, 0, event);
511                 if (IS_ERR(msg))
512                         return PTR_ERR(msg);
513
514                 genlmsg_multicast(msg, 0, GENL_ID_CTRL);
515                 break;
516         }
517
518         return 0;
519 }
520
521 static struct genl_ops genl_ctrl_ops = {
522         .cmd            = CTRL_CMD_GETFAMILY,
523         .doit           = ctrl_getfamily,
524         .dumpit         = ctrl_dumpfamily,
525         .policy         = ctrl_policy,
526 };
527
528 static struct genl_family genl_ctrl = {
529         .id = GENL_ID_CTRL,
530         .name = "nlctrl",
531         .version = 0x1,
532         .maxattr = CTRL_ATTR_MAX,
533 };
534
535 static int __init genl_init(void)
536 {
537         int i, err;
538
539         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
540                 INIT_LIST_HEAD(&family_ht[i]);
541
542         err = genl_register_family(&genl_ctrl);
543         if (err < 0)
544                 goto errout;
545
546         err = genl_register_ops(&genl_ctrl, &genl_ctrl_ops);
547         if (err < 0)
548                 goto errout_register;
549
550         netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);
551         genl_sock = netlink_kernel_create(NETLINK_GENERIC, GENL_MAX_ID,
552                                           genl_rcv, THIS_MODULE);
553         if (genl_sock == NULL)
554                 panic("GENL: Cannot initialize generic netlink\n");
555
556         return 0;
557
558 errout_register:
559         genl_unregister_family(&genl_ctrl);
560 errout:
561         panic("GENL: Cannot register controller: %d\n", err);
562 }
563
564 subsys_initcall(genl_init);
565
566 EXPORT_SYMBOL(genl_sock);
567 EXPORT_SYMBOL(genl_register_ops);
568 EXPORT_SYMBOL(genl_unregister_ops);
569 EXPORT_SYMBOL(genl_register_family);
570 EXPORT_SYMBOL(genl_unregister_family);