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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> | |
29 | ||
30 | #include <net/sock.h> | |
31 | ||
32 | MODULE_LICENSE("GPL"); | |
33 | MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>"); | |
34 | MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector."); | |
35 | ||
36 | static u32 cn_idx = CN_IDX_CONNECTOR; | |
37 | static u32 cn_val = CN_VAL_CONNECTOR; | |
38 | ||
39 | module_param(cn_idx, uint, 0); | |
40 | module_param(cn_val, uint, 0); | |
41 | MODULE_PARM_DESC(cn_idx, "Connector's main device idx."); | |
42 | MODULE_PARM_DESC(cn_val, "Connector's main device val."); | |
43 | ||
44 | static DECLARE_MUTEX(notify_lock); | |
45 | static LIST_HEAD(notify_list); | |
46 | ||
47 | static struct cn_dev cdev; | |
48 | ||
49 | int cn_already_initialized = 0; | |
50 | ||
51 | /* | |
52 | * msg->seq and msg->ack are used to determine message genealogy. | |
53 | * When someone sends message it puts there locally unique sequence | |
54 | * and random acknowledge numbers. Sequence number may be copied into | |
55 | * nlmsghdr->nlmsg_seq too. | |
56 | * | |
57 | * Sequence number is incremented with each message to be sent. | |
58 | * | |
59 | * If we expect reply to our message then the sequence number in | |
60 | * received message MUST be the same as in original message, and | |
61 | * acknowledge number MUST be the same + 1. | |
62 | * | |
63 | * If we receive a message and its sequence number is not equal to the | |
64 | * one we are expecting then it is a new message. | |
65 | * | |
66 | * If we receive a message and its sequence number is the same as one | |
67 | * we are expecting but it's acknowledgement number is not equal to | |
68 | * the acknowledgement number in the original message + 1, then it is | |
69 | * a new message. | |
70 | * | |
71 | */ | |
72 | int cn_netlink_send(struct cn_msg *msg, u32 __group, int gfp_mask) | |
73 | { | |
74 | struct cn_callback_entry *__cbq; | |
75 | unsigned int size; | |
76 | struct sk_buff *skb; | |
77 | struct nlmsghdr *nlh; | |
78 | struct cn_msg *data; | |
79 | struct cn_dev *dev = &cdev; | |
80 | u32 group = 0; | |
81 | int found = 0; | |
82 | ||
83 | if (!__group) { | |
84 | spin_lock_bh(&dev->cbdev->queue_lock); | |
85 | list_for_each_entry(__cbq, &dev->cbdev->queue_list, | |
86 | callback_entry) { | |
87 | if (cn_cb_equal(&__cbq->cb->id, &msg->id)) { | |
88 | found = 1; | |
89 | group = __cbq->group; | |
90 | } | |
91 | } | |
92 | spin_unlock_bh(&dev->cbdev->queue_lock); | |
93 | ||
94 | if (!found) | |
95 | return -ENODEV; | |
96 | } else { | |
97 | group = __group; | |
98 | } | |
99 | ||
100 | size = NLMSG_SPACE(sizeof(*msg) + msg->len); | |
101 | ||
102 | skb = alloc_skb(size, gfp_mask); | |
103 | if (!skb) | |
104 | return -ENOMEM; | |
105 | ||
106 | nlh = NLMSG_PUT(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh)); | |
107 | ||
108 | data = NLMSG_DATA(nlh); | |
109 | ||
110 | memcpy(data, msg, sizeof(*data) + msg->len); | |
111 | ||
112 | NETLINK_CB(skb).dst_group = group; | |
113 | ||
114 | netlink_broadcast(dev->nls, skb, 0, group, gfp_mask); | |
115 | ||
116 | return 0; | |
117 | ||
118 | nlmsg_failure: | |
119 | kfree_skb(skb); | |
120 | return -EINVAL; | |
121 | } | |
122 | ||
123 | /* | |
124 | * Callback helper - queues work and setup destructor for given data. | |
125 | */ | |
126 | static int cn_call_callback(struct cn_msg *msg, void (*destruct_data)(void *), void *data) | |
127 | { | |
128 | struct cn_callback_entry *__cbq; | |
129 | struct cn_dev *dev = &cdev; | |
130 | int found = 0; | |
131 | ||
132 | spin_lock_bh(&dev->cbdev->queue_lock); | |
133 | list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) { | |
134 | if (cn_cb_equal(&__cbq->cb->id, &msg->id)) { | |
135 | /* | |
136 | * Let's scream if there is some magic and the | |
137 | * data will arrive asynchronously here. | |
138 | * [i.e. netlink messages will be queued]. | |
139 | * After the first warning I will fix it | |
140 | * quickly, but now I think it is | |
141 | * impossible. --zbr (2004_04_27). | |
142 | */ | |
143 | if (likely(!test_bit(0, &__cbq->work.pending) && | |
144 | __cbq->ddata == NULL)) { | |
145 | __cbq->cb->priv = msg; | |
146 | ||
147 | __cbq->ddata = data; | |
148 | __cbq->destruct_data = destruct_data; | |
149 | ||
150 | if (queue_work(dev->cbdev->cn_queue, | |
151 | &__cbq->work)) | |
152 | found = 1; | |
153 | } else { | |
154 | printk("%s: cbq->data=%p, " | |
155 | "work->pending=%08lx.\n", | |
156 | __func__, __cbq->ddata, | |
157 | __cbq->work.pending); | |
158 | WARN_ON(1); | |
159 | } | |
160 | break; | |
161 | } | |
162 | } | |
163 | spin_unlock_bh(&dev->cbdev->queue_lock); | |
164 | ||
165 | return found ? 0 : -ENODEV; | |
166 | } | |
167 | ||
168 | /* | |
169 | * Skb receive helper - checks skb and msg size and calls callback | |
170 | * helper. | |
171 | */ | |
172 | static int __cn_rx_skb(struct sk_buff *skb, struct nlmsghdr *nlh) | |
173 | { | |
174 | u32 pid, uid, seq, group; | |
175 | struct cn_msg *msg; | |
176 | ||
177 | pid = NETLINK_CREDS(skb)->pid; | |
178 | uid = NETLINK_CREDS(skb)->uid; | |
179 | seq = nlh->nlmsg_seq; | |
180 | group = NETLINK_CB((skb)).dst_group; | |
181 | msg = NLMSG_DATA(nlh); | |
182 | ||
183 | return cn_call_callback(msg, (void (*)(void *))kfree_skb, skb); | |
184 | } | |
185 | ||
186 | /* | |
187 | * Main netlink receiving function. | |
188 | * | |
189 | * It checks skb and netlink header sizes and calls the skb receive | |
190 | * helper with a shared skb. | |
191 | */ | |
192 | static void cn_rx_skb(struct sk_buff *__skb) | |
193 | { | |
194 | struct nlmsghdr *nlh; | |
195 | u32 len; | |
196 | int err; | |
197 | struct sk_buff *skb; | |
198 | ||
199 | skb = skb_get(__skb); | |
200 | ||
201 | if (skb->len >= NLMSG_SPACE(0)) { | |
202 | nlh = (struct nlmsghdr *)skb->data; | |
203 | ||
204 | if (nlh->nlmsg_len < sizeof(struct cn_msg) || | |
205 | skb->len < nlh->nlmsg_len || | |
206 | nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) { | |
207 | kfree_skb(skb); | |
208 | goto out; | |
209 | } | |
210 | ||
211 | len = NLMSG_ALIGN(nlh->nlmsg_len); | |
212 | if (len > skb->len) | |
213 | len = skb->len; | |
214 | ||
215 | err = __cn_rx_skb(skb, nlh); | |
216 | if (err < 0) | |
217 | kfree_skb(skb); | |
218 | } | |
219 | ||
220 | out: | |
221 | kfree_skb(__skb); | |
222 | } | |
223 | ||
224 | /* | |
225 | * Netlink socket input callback - dequeues the skbs and calls the | |
226 | * main netlink receiving function. | |
227 | */ | |
228 | static void cn_input(struct sock *sk, int len) | |
229 | { | |
230 | struct sk_buff *skb; | |
231 | ||
232 | while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) | |
233 | cn_rx_skb(skb); | |
234 | } | |
235 | ||
236 | /* | |
237 | * Notification routing. | |
238 | * | |
239 | * Gets id and checks if there are notification request for it's idx | |
240 | * and val. If there are such requests notify the listeners with the | |
241 | * given notify event. | |
242 | * | |
243 | */ | |
244 | static void cn_notify(struct cb_id *id, u32 notify_event) | |
245 | { | |
246 | struct cn_ctl_entry *ent; | |
247 | ||
248 | down(¬ify_lock); | |
249 | list_for_each_entry(ent, ¬ify_list, notify_entry) { | |
250 | int i; | |
251 | struct cn_notify_req *req; | |
252 | struct cn_ctl_msg *ctl = ent->msg; | |
253 | int idx_found, val_found; | |
254 | ||
255 | idx_found = val_found = 0; | |
256 | ||
257 | req = (struct cn_notify_req *)ctl->data; | |
258 | for (i = 0; i < ctl->idx_notify_num; ++i, ++req) { | |
259 | if (id->idx >= req->first && | |
260 | id->idx < req->first + req->range) { | |
261 | idx_found = 1; | |
262 | break; | |
263 | } | |
264 | } | |
265 | ||
266 | for (i = 0; i < ctl->val_notify_num; ++i, ++req) { | |
267 | if (id->val >= req->first && | |
268 | id->val < req->first + req->range) { | |
269 | val_found = 1; | |
270 | break; | |
271 | } | |
272 | } | |
273 | ||
274 | if (idx_found && val_found) { | |
275 | struct cn_msg m = { .ack = notify_event, }; | |
276 | ||
277 | memcpy(&m.id, id, sizeof(m.id)); | |
278 | cn_netlink_send(&m, ctl->group, GFP_KERNEL); | |
279 | } | |
280 | } | |
281 | up(¬ify_lock); | |
282 | } | |
283 | ||
284 | /* | |
285 | * Callback add routing - adds callback with given ID and name. | |
286 | * If there is registered callback with the same ID it will not be added. | |
287 | * | |
288 | * May sleep. | |
289 | */ | |
290 | int cn_add_callback(struct cb_id *id, char *name, void (*callback)(void *)) | |
291 | { | |
292 | int err; | |
293 | struct cn_dev *dev = &cdev; | |
294 | struct cn_callback *cb; | |
295 | ||
296 | cb = kzalloc(sizeof(*cb), GFP_KERNEL); | |
297 | if (!cb) | |
298 | return -ENOMEM; | |
299 | ||
300 | scnprintf(cb->name, sizeof(cb->name), "%s", name); | |
301 | ||
302 | memcpy(&cb->id, id, sizeof(cb->id)); | |
303 | cb->callback = callback; | |
304 | ||
305 | err = cn_queue_add_callback(dev->cbdev, cb); | |
306 | if (err) { | |
307 | kfree(cb); | |
308 | return err; | |
309 | } | |
310 | ||
311 | cn_notify(id, 0); | |
312 | ||
313 | return 0; | |
314 | } | |
315 | ||
316 | /* | |
317 | * Callback remove routing - removes callback | |
318 | * with given ID. | |
319 | * If there is no registered callback with given | |
320 | * ID nothing happens. | |
321 | * | |
322 | * May sleep while waiting for reference counter to become zero. | |
323 | */ | |
324 | void cn_del_callback(struct cb_id *id) | |
325 | { | |
326 | struct cn_dev *dev = &cdev; | |
327 | ||
328 | cn_queue_del_callback(dev->cbdev, id); | |
329 | cn_notify(id, 1); | |
330 | } | |
331 | ||
332 | /* | |
333 | * Checks two connector's control messages to be the same. | |
334 | * Returns 1 if they are the same or if the first one is corrupted. | |
335 | */ | |
336 | static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2) | |
337 | { | |
338 | int i; | |
339 | struct cn_notify_req *req1, *req2; | |
340 | ||
341 | if (m1->idx_notify_num != m2->idx_notify_num) | |
342 | return 0; | |
343 | ||
344 | if (m1->val_notify_num != m2->val_notify_num) | |
345 | return 0; | |
346 | ||
347 | if (m1->len != m2->len) | |
348 | return 0; | |
349 | ||
350 | if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) != | |
351 | m1->len) | |
352 | return 1; | |
353 | ||
354 | req1 = (struct cn_notify_req *)m1->data; | |
355 | req2 = (struct cn_notify_req *)m2->data; | |
356 | ||
357 | for (i = 0; i < m1->idx_notify_num; ++i) { | |
358 | if (req1->first != req2->first || req1->range != req2->range) | |
359 | return 0; | |
360 | req1++; | |
361 | req2++; | |
362 | } | |
363 | ||
364 | for (i = 0; i < m1->val_notify_num; ++i) { | |
365 | if (req1->first != req2->first || req1->range != req2->range) | |
366 | return 0; | |
367 | req1++; | |
368 | req2++; | |
369 | } | |
370 | ||
371 | return 1; | |
372 | } | |
373 | ||
374 | /* | |
375 | * Main connector device's callback. | |
376 | * | |
377 | * Used for notification of a request's processing. | |
378 | */ | |
379 | static void cn_callback(void *data) | |
380 | { | |
381 | struct cn_msg *msg = data; | |
382 | struct cn_ctl_msg *ctl; | |
383 | struct cn_ctl_entry *ent; | |
384 | u32 size; | |
385 | ||
386 | if (msg->len < sizeof(*ctl)) | |
387 | return; | |
388 | ||
389 | ctl = (struct cn_ctl_msg *)msg->data; | |
390 | ||
391 | size = (sizeof(*ctl) + ((ctl->idx_notify_num + | |
392 | ctl->val_notify_num) * | |
393 | sizeof(struct cn_notify_req))); | |
394 | ||
395 | if (msg->len != size) | |
396 | return; | |
397 | ||
398 | if (ctl->len + sizeof(*ctl) != msg->len) | |
399 | return; | |
400 | ||
401 | /* | |
402 | * Remove notification. | |
403 | */ | |
404 | if (ctl->group == 0) { | |
405 | struct cn_ctl_entry *n; | |
406 | ||
407 | down(¬ify_lock); | |
408 | list_for_each_entry_safe(ent, n, ¬ify_list, notify_entry) { | |
409 | if (cn_ctl_msg_equals(ent->msg, ctl)) { | |
410 | list_del(&ent->notify_entry); | |
411 | kfree(ent); | |
412 | } | |
413 | } | |
414 | up(¬ify_lock); | |
415 | ||
416 | return; | |
417 | } | |
418 | ||
419 | size += sizeof(*ent); | |
420 | ||
421 | ent = kzalloc(size, GFP_KERNEL); | |
422 | if (!ent) | |
423 | return; | |
424 | ||
425 | ent->msg = (struct cn_ctl_msg *)(ent + 1); | |
426 | ||
427 | memcpy(ent->msg, ctl, size - sizeof(*ent)); | |
428 | ||
429 | down(¬ify_lock); | |
430 | list_add(&ent->notify_entry, ¬ify_list); | |
431 | up(¬ify_lock); | |
432 | } | |
433 | ||
434 | static int __init cn_init(void) | |
435 | { | |
436 | struct cn_dev *dev = &cdev; | |
437 | int err; | |
438 | ||
439 | dev->input = cn_input; | |
440 | dev->id.idx = cn_idx; | |
441 | dev->id.val = cn_val; | |
442 | ||
443 | dev->nls = netlink_kernel_create(NETLINK_CONNECTOR, | |
444 | CN_NETLINK_USERS + 0xf, | |
445 | dev->input, THIS_MODULE); | |
446 | if (!dev->nls) | |
447 | return -EIO; | |
448 | ||
449 | dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls); | |
450 | if (!dev->cbdev) { | |
451 | if (dev->nls->sk_socket) | |
452 | sock_release(dev->nls->sk_socket); | |
453 | return -EINVAL; | |
454 | } | |
455 | ||
456 | err = cn_add_callback(&dev->id, "connector", &cn_callback); | |
457 | if (err) { | |
458 | cn_queue_free_dev(dev->cbdev); | |
459 | if (dev->nls->sk_socket) | |
460 | sock_release(dev->nls->sk_socket); | |
461 | return -EINVAL; | |
462 | } | |
463 | ||
464 | cn_already_initialized = 1; | |
465 | ||
466 | return 0; | |
467 | } | |
468 | ||
469 | static void __exit cn_fini(void) | |
470 | { | |
471 | struct cn_dev *dev = &cdev; | |
472 | ||
473 | cn_already_initialized = 0; | |
474 | ||
475 | cn_del_callback(&dev->id); | |
476 | cn_queue_free_dev(dev->cbdev); | |
477 | if (dev->nls->sk_socket) | |
478 | sock_release(dev->nls->sk_socket); | |
479 | } | |
480 | ||
481 | module_init(cn_init); | |
482 | module_exit(cn_fini); | |
483 | ||
484 | EXPORT_SYMBOL_GPL(cn_add_callback); | |
485 | EXPORT_SYMBOL_GPL(cn_del_callback); | |
486 | EXPORT_SYMBOL_GPL(cn_netlink_send); |