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7672d0b5 EP |
1 | /* |
2 | * connector.c | |
3 | * | |
4 | * 2004-2005 Copyright (c) Evgeniy Polyakov <johnpol@2ka.mipt.ru> | |
5 | * All rights reserved. | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License as published by | |
9 | * the Free Software Foundation; either version 2 of the License, or | |
10 | * (at your option) any later version. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | * GNU General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License | |
18 | * along with this program; if not, write to the Free Software | |
19 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
20 | */ | |
21 | ||
22 | #include <linux/kernel.h> | |
23 | #include <linux/module.h> | |
24 | #include <linux/list.h> | |
25 | #include <linux/skbuff.h> | |
26 | #include <linux/netlink.h> | |
27 | #include <linux/moduleparam.h> | |
28 | #include <linux/connector.h> | |
8ed965d6 | 29 | #include <linux/mutex.h> |
7672d0b5 EP |
30 | |
31 | #include <net/sock.h> | |
32 | ||
33 | MODULE_LICENSE("GPL"); | |
34 | MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>"); | |
35 | MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector."); | |
36 | ||
37 | static u32 cn_idx = CN_IDX_CONNECTOR; | |
38 | static u32 cn_val = CN_VAL_CONNECTOR; | |
39 | ||
40 | module_param(cn_idx, uint, 0); | |
41 | module_param(cn_val, uint, 0); | |
42 | MODULE_PARM_DESC(cn_idx, "Connector's main device idx."); | |
43 | MODULE_PARM_DESC(cn_val, "Connector's main device val."); | |
44 | ||
8ed965d6 | 45 | static DEFINE_MUTEX(notify_lock); |
7672d0b5 EP |
46 | static LIST_HEAD(notify_list); |
47 | ||
48 | static struct cn_dev cdev; | |
49 | ||
50 | int cn_already_initialized = 0; | |
51 | ||
52 | /* | |
53 | * msg->seq and msg->ack are used to determine message genealogy. | |
54 | * When someone sends message it puts there locally unique sequence | |
55 | * and random acknowledge numbers. Sequence number may be copied into | |
56 | * nlmsghdr->nlmsg_seq too. | |
57 | * | |
58 | * Sequence number is incremented with each message to be sent. | |
59 | * | |
60 | * If we expect reply to our message then the sequence number in | |
61 | * received message MUST be the same as in original message, and | |
62 | * acknowledge number MUST be the same + 1. | |
63 | * | |
64 | * If we receive a message and its sequence number is not equal to the | |
65 | * one we are expecting then it is a new message. | |
66 | * | |
67 | * If we receive a message and its sequence number is the same as one | |
68 | * we are expecting but it's acknowledgement number is not equal to | |
69 | * the acknowledgement number in the original message + 1, then it is | |
70 | * a new message. | |
71 | * | |
72 | */ | |
dd0fc66f | 73 | int cn_netlink_send(struct cn_msg *msg, u32 __group, gfp_t gfp_mask) |
7672d0b5 EP |
74 | { |
75 | struct cn_callback_entry *__cbq; | |
76 | unsigned int size; | |
77 | struct sk_buff *skb; | |
78 | struct nlmsghdr *nlh; | |
79 | struct cn_msg *data; | |
80 | struct cn_dev *dev = &cdev; | |
81 | u32 group = 0; | |
82 | int found = 0; | |
83 | ||
84 | if (!__group) { | |
85 | spin_lock_bh(&dev->cbdev->queue_lock); | |
86 | list_for_each_entry(__cbq, &dev->cbdev->queue_list, | |
87 | callback_entry) { | |
acd042bb | 88 | if (cn_cb_equal(&__cbq->id.id, &msg->id)) { |
7672d0b5 EP |
89 | found = 1; |
90 | group = __cbq->group; | |
91 | } | |
92 | } | |
93 | spin_unlock_bh(&dev->cbdev->queue_lock); | |
94 | ||
95 | if (!found) | |
96 | return -ENODEV; | |
97 | } else { | |
98 | group = __group; | |
99 | } | |
100 | ||
b191ba0d EP |
101 | if (!netlink_has_listeners(dev->nls, group)) |
102 | return -ESRCH; | |
103 | ||
7672d0b5 EP |
104 | size = NLMSG_SPACE(sizeof(*msg) + msg->len); |
105 | ||
106 | skb = alloc_skb(size, gfp_mask); | |
107 | if (!skb) | |
108 | return -ENOMEM; | |
109 | ||
110 | nlh = NLMSG_PUT(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh)); | |
111 | ||
112 | data = NLMSG_DATA(nlh); | |
113 | ||
114 | memcpy(data, msg, sizeof(*data) + msg->len); | |
115 | ||
116 | NETLINK_CB(skb).dst_group = group; | |
117 | ||
b191ba0d | 118 | return netlink_broadcast(dev->nls, skb, 0, group, gfp_mask); |
7672d0b5 EP |
119 | |
120 | nlmsg_failure: | |
121 | kfree_skb(skb); | |
122 | return -EINVAL; | |
123 | } | |
124 | ||
125 | /* | |
126 | * Callback helper - queues work and setup destructor for given data. | |
127 | */ | |
128 | static int cn_call_callback(struct cn_msg *msg, void (*destruct_data)(void *), void *data) | |
129 | { | |
130 | struct cn_callback_entry *__cbq; | |
131 | struct cn_dev *dev = &cdev; | |
acd042bb | 132 | int err = -ENODEV; |
7672d0b5 EP |
133 | |
134 | spin_lock_bh(&dev->cbdev->queue_lock); | |
135 | list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) { | |
acd042bb | 136 | if (cn_cb_equal(&__cbq->id.id, &msg->id)) { |
7672d0b5 | 137 | if (likely(!test_bit(0, &__cbq->work.pending) && |
acd042bb EP |
138 | __cbq->data.ddata == NULL)) { |
139 | __cbq->data.callback_priv = msg; | |
7672d0b5 | 140 | |
acd042bb EP |
141 | __cbq->data.ddata = data; |
142 | __cbq->data.destruct_data = destruct_data; | |
7672d0b5 EP |
143 | |
144 | if (queue_work(dev->cbdev->cn_queue, | |
145 | &__cbq->work)) | |
acd042bb | 146 | err = 0; |
7672d0b5 | 147 | } else { |
acd042bb EP |
148 | struct work_struct *w; |
149 | struct cn_callback_data *d; | |
150 | ||
151 | w = kzalloc(sizeof(*w) + sizeof(*d), GFP_ATOMIC); | |
152 | if (w) { | |
153 | d = (struct cn_callback_data *)(w+1); | |
154 | ||
155 | d->callback_priv = msg; | |
156 | d->callback = __cbq->data.callback; | |
157 | d->ddata = data; | |
158 | d->destruct_data = destruct_data; | |
159 | d->free = w; | |
160 | ||
161 | INIT_LIST_HEAD(&w->entry); | |
162 | w->pending = 0; | |
163 | w->func = &cn_queue_wrapper; | |
164 | w->data = d; | |
165 | init_timer(&w->timer); | |
166 | ||
167 | if (queue_work(dev->cbdev->cn_queue, w)) | |
168 | err = 0; | |
169 | else { | |
170 | kfree(w); | |
171 | err = -EINVAL; | |
172 | } | |
173 | } else | |
174 | err = -ENOMEM; | |
7672d0b5 EP |
175 | } |
176 | break; | |
177 | } | |
178 | } | |
179 | spin_unlock_bh(&dev->cbdev->queue_lock); | |
180 | ||
acd042bb | 181 | return err; |
7672d0b5 EP |
182 | } |
183 | ||
184 | /* | |
185 | * Skb receive helper - checks skb and msg size and calls callback | |
186 | * helper. | |
187 | */ | |
188 | static int __cn_rx_skb(struct sk_buff *skb, struct nlmsghdr *nlh) | |
189 | { | |
190 | u32 pid, uid, seq, group; | |
191 | struct cn_msg *msg; | |
192 | ||
193 | pid = NETLINK_CREDS(skb)->pid; | |
194 | uid = NETLINK_CREDS(skb)->uid; | |
195 | seq = nlh->nlmsg_seq; | |
196 | group = NETLINK_CB((skb)).dst_group; | |
197 | msg = NLMSG_DATA(nlh); | |
198 | ||
199 | return cn_call_callback(msg, (void (*)(void *))kfree_skb, skb); | |
200 | } | |
201 | ||
202 | /* | |
203 | * Main netlink receiving function. | |
204 | * | |
205 | * It checks skb and netlink header sizes and calls the skb receive | |
206 | * helper with a shared skb. | |
207 | */ | |
208 | static void cn_rx_skb(struct sk_buff *__skb) | |
209 | { | |
210 | struct nlmsghdr *nlh; | |
211 | u32 len; | |
212 | int err; | |
213 | struct sk_buff *skb; | |
214 | ||
215 | skb = skb_get(__skb); | |
216 | ||
217 | if (skb->len >= NLMSG_SPACE(0)) { | |
218 | nlh = (struct nlmsghdr *)skb->data; | |
219 | ||
220 | if (nlh->nlmsg_len < sizeof(struct cn_msg) || | |
221 | skb->len < nlh->nlmsg_len || | |
222 | nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) { | |
223 | kfree_skb(skb); | |
224 | goto out; | |
225 | } | |
226 | ||
227 | len = NLMSG_ALIGN(nlh->nlmsg_len); | |
228 | if (len > skb->len) | |
229 | len = skb->len; | |
230 | ||
231 | err = __cn_rx_skb(skb, nlh); | |
232 | if (err < 0) | |
233 | kfree_skb(skb); | |
234 | } | |
235 | ||
236 | out: | |
237 | kfree_skb(__skb); | |
238 | } | |
239 | ||
240 | /* | |
241 | * Netlink socket input callback - dequeues the skbs and calls the | |
242 | * main netlink receiving function. | |
243 | */ | |
244 | static void cn_input(struct sock *sk, int len) | |
245 | { | |
246 | struct sk_buff *skb; | |
247 | ||
248 | while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) | |
249 | cn_rx_skb(skb); | |
250 | } | |
251 | ||
252 | /* | |
253 | * Notification routing. | |
254 | * | |
255 | * Gets id and checks if there are notification request for it's idx | |
256 | * and val. If there are such requests notify the listeners with the | |
257 | * given notify event. | |
258 | * | |
259 | */ | |
260 | static void cn_notify(struct cb_id *id, u32 notify_event) | |
261 | { | |
262 | struct cn_ctl_entry *ent; | |
263 | ||
8ed965d6 | 264 | mutex_lock(¬ify_lock); |
7672d0b5 EP |
265 | list_for_each_entry(ent, ¬ify_list, notify_entry) { |
266 | int i; | |
267 | struct cn_notify_req *req; | |
268 | struct cn_ctl_msg *ctl = ent->msg; | |
269 | int idx_found, val_found; | |
270 | ||
271 | idx_found = val_found = 0; | |
272 | ||
273 | req = (struct cn_notify_req *)ctl->data; | |
274 | for (i = 0; i < ctl->idx_notify_num; ++i, ++req) { | |
275 | if (id->idx >= req->first && | |
276 | id->idx < req->first + req->range) { | |
277 | idx_found = 1; | |
278 | break; | |
279 | } | |
280 | } | |
281 | ||
282 | for (i = 0; i < ctl->val_notify_num; ++i, ++req) { | |
283 | if (id->val >= req->first && | |
284 | id->val < req->first + req->range) { | |
285 | val_found = 1; | |
286 | break; | |
287 | } | |
288 | } | |
289 | ||
290 | if (idx_found && val_found) { | |
291 | struct cn_msg m = { .ack = notify_event, }; | |
292 | ||
293 | memcpy(&m.id, id, sizeof(m.id)); | |
294 | cn_netlink_send(&m, ctl->group, GFP_KERNEL); | |
295 | } | |
296 | } | |
8ed965d6 | 297 | mutex_unlock(¬ify_lock); |
7672d0b5 EP |
298 | } |
299 | ||
300 | /* | |
301 | * Callback add routing - adds callback with given ID and name. | |
302 | * If there is registered callback with the same ID it will not be added. | |
303 | * | |
304 | * May sleep. | |
305 | */ | |
306 | int cn_add_callback(struct cb_id *id, char *name, void (*callback)(void *)) | |
307 | { | |
308 | int err; | |
309 | struct cn_dev *dev = &cdev; | |
7672d0b5 | 310 | |
acd042bb EP |
311 | err = cn_queue_add_callback(dev->cbdev, name, id, callback); |
312 | if (err) | |
7672d0b5 | 313 | return err; |
7672d0b5 EP |
314 | |
315 | cn_notify(id, 0); | |
316 | ||
317 | return 0; | |
318 | } | |
319 | ||
320 | /* | |
321 | * Callback remove routing - removes callback | |
322 | * with given ID. | |
323 | * If there is no registered callback with given | |
324 | * ID nothing happens. | |
325 | * | |
326 | * May sleep while waiting for reference counter to become zero. | |
327 | */ | |
328 | void cn_del_callback(struct cb_id *id) | |
329 | { | |
330 | struct cn_dev *dev = &cdev; | |
331 | ||
332 | cn_queue_del_callback(dev->cbdev, id); | |
333 | cn_notify(id, 1); | |
334 | } | |
335 | ||
336 | /* | |
337 | * Checks two connector's control messages to be the same. | |
338 | * Returns 1 if they are the same or if the first one is corrupted. | |
339 | */ | |
340 | static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2) | |
341 | { | |
342 | int i; | |
343 | struct cn_notify_req *req1, *req2; | |
344 | ||
345 | if (m1->idx_notify_num != m2->idx_notify_num) | |
346 | return 0; | |
347 | ||
348 | if (m1->val_notify_num != m2->val_notify_num) | |
349 | return 0; | |
350 | ||
351 | if (m1->len != m2->len) | |
352 | return 0; | |
353 | ||
354 | if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) != | |
355 | m1->len) | |
356 | return 1; | |
357 | ||
358 | req1 = (struct cn_notify_req *)m1->data; | |
359 | req2 = (struct cn_notify_req *)m2->data; | |
360 | ||
361 | for (i = 0; i < m1->idx_notify_num; ++i) { | |
362 | if (req1->first != req2->first || req1->range != req2->range) | |
363 | return 0; | |
364 | req1++; | |
365 | req2++; | |
366 | } | |
367 | ||
368 | for (i = 0; i < m1->val_notify_num; ++i) { | |
369 | if (req1->first != req2->first || req1->range != req2->range) | |
370 | return 0; | |
371 | req1++; | |
372 | req2++; | |
373 | } | |
374 | ||
375 | return 1; | |
376 | } | |
377 | ||
378 | /* | |
379 | * Main connector device's callback. | |
380 | * | |
381 | * Used for notification of a request's processing. | |
382 | */ | |
383 | static void cn_callback(void *data) | |
384 | { | |
385 | struct cn_msg *msg = data; | |
386 | struct cn_ctl_msg *ctl; | |
387 | struct cn_ctl_entry *ent; | |
388 | u32 size; | |
389 | ||
390 | if (msg->len < sizeof(*ctl)) | |
391 | return; | |
392 | ||
393 | ctl = (struct cn_ctl_msg *)msg->data; | |
394 | ||
395 | size = (sizeof(*ctl) + ((ctl->idx_notify_num + | |
396 | ctl->val_notify_num) * | |
397 | sizeof(struct cn_notify_req))); | |
398 | ||
399 | if (msg->len != size) | |
400 | return; | |
401 | ||
402 | if (ctl->len + sizeof(*ctl) != msg->len) | |
403 | return; | |
404 | ||
405 | /* | |
406 | * Remove notification. | |
407 | */ | |
408 | if (ctl->group == 0) { | |
409 | struct cn_ctl_entry *n; | |
410 | ||
8ed965d6 | 411 | mutex_lock(¬ify_lock); |
7672d0b5 EP |
412 | list_for_each_entry_safe(ent, n, ¬ify_list, notify_entry) { |
413 | if (cn_ctl_msg_equals(ent->msg, ctl)) { | |
414 | list_del(&ent->notify_entry); | |
415 | kfree(ent); | |
416 | } | |
417 | } | |
8ed965d6 | 418 | mutex_unlock(¬ify_lock); |
7672d0b5 EP |
419 | |
420 | return; | |
421 | } | |
422 | ||
423 | size += sizeof(*ent); | |
424 | ||
425 | ent = kzalloc(size, GFP_KERNEL); | |
426 | if (!ent) | |
427 | return; | |
428 | ||
429 | ent->msg = (struct cn_ctl_msg *)(ent + 1); | |
430 | ||
431 | memcpy(ent->msg, ctl, size - sizeof(*ent)); | |
432 | ||
8ed965d6 | 433 | mutex_lock(¬ify_lock); |
7672d0b5 | 434 | list_add(&ent->notify_entry, ¬ify_list); |
8ed965d6 | 435 | mutex_unlock(¬ify_lock); |
7672d0b5 EP |
436 | } |
437 | ||
438 | static int __init cn_init(void) | |
439 | { | |
440 | struct cn_dev *dev = &cdev; | |
441 | int err; | |
442 | ||
443 | dev->input = cn_input; | |
444 | dev->id.idx = cn_idx; | |
445 | dev->id.val = cn_val; | |
446 | ||
447 | dev->nls = netlink_kernel_create(NETLINK_CONNECTOR, | |
448 | CN_NETLINK_USERS + 0xf, | |
449 | dev->input, THIS_MODULE); | |
450 | if (!dev->nls) | |
451 | return -EIO; | |
452 | ||
453 | dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls); | |
454 | if (!dev->cbdev) { | |
455 | if (dev->nls->sk_socket) | |
456 | sock_release(dev->nls->sk_socket); | |
457 | return -EINVAL; | |
458 | } | |
459 | ||
460 | err = cn_add_callback(&dev->id, "connector", &cn_callback); | |
461 | if (err) { | |
462 | cn_queue_free_dev(dev->cbdev); | |
463 | if (dev->nls->sk_socket) | |
464 | sock_release(dev->nls->sk_socket); | |
465 | return -EINVAL; | |
466 | } | |
467 | ||
468 | cn_already_initialized = 1; | |
469 | ||
470 | return 0; | |
471 | } | |
472 | ||
473 | static void __exit cn_fini(void) | |
474 | { | |
475 | struct cn_dev *dev = &cdev; | |
476 | ||
477 | cn_already_initialized = 0; | |
478 | ||
479 | cn_del_callback(&dev->id); | |
480 | cn_queue_free_dev(dev->cbdev); | |
481 | if (dev->nls->sk_socket) | |
482 | sock_release(dev->nls->sk_socket); | |
483 | } | |
484 | ||
485 | module_init(cn_init); | |
486 | module_exit(cn_fini); | |
487 | ||
488 | EXPORT_SYMBOL_GPL(cn_add_callback); | |
489 | EXPORT_SYMBOL_GPL(cn_del_callback); | |
490 | EXPORT_SYMBOL_GPL(cn_netlink_send); |