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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 | */ | |
dd0fc66f | 72 | int cn_netlink_send(struct cn_msg *msg, u32 __group, gfp_t gfp_mask) |
7672d0b5 EP |
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) { | |
acd042bb | 87 | if (cn_cb_equal(&__cbq->id.id, &msg->id)) { |
7672d0b5 EP |
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; | |
acd042bb | 130 | int err = -ENODEV; |
7672d0b5 EP |
131 | |
132 | spin_lock_bh(&dev->cbdev->queue_lock); | |
133 | list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) { | |
acd042bb | 134 | if (cn_cb_equal(&__cbq->id.id, &msg->id)) { |
7672d0b5 | 135 | if (likely(!test_bit(0, &__cbq->work.pending) && |
acd042bb EP |
136 | __cbq->data.ddata == NULL)) { |
137 | __cbq->data.callback_priv = msg; | |
7672d0b5 | 138 | |
acd042bb EP |
139 | __cbq->data.ddata = data; |
140 | __cbq->data.destruct_data = destruct_data; | |
7672d0b5 EP |
141 | |
142 | if (queue_work(dev->cbdev->cn_queue, | |
143 | &__cbq->work)) | |
acd042bb | 144 | err = 0; |
7672d0b5 | 145 | } else { |
acd042bb EP |
146 | struct work_struct *w; |
147 | struct cn_callback_data *d; | |
148 | ||
149 | w = kzalloc(sizeof(*w) + sizeof(*d), GFP_ATOMIC); | |
150 | if (w) { | |
151 | d = (struct cn_callback_data *)(w+1); | |
152 | ||
153 | d->callback_priv = msg; | |
154 | d->callback = __cbq->data.callback; | |
155 | d->ddata = data; | |
156 | d->destruct_data = destruct_data; | |
157 | d->free = w; | |
158 | ||
159 | INIT_LIST_HEAD(&w->entry); | |
160 | w->pending = 0; | |
161 | w->func = &cn_queue_wrapper; | |
162 | w->data = d; | |
163 | init_timer(&w->timer); | |
164 | ||
165 | if (queue_work(dev->cbdev->cn_queue, w)) | |
166 | err = 0; | |
167 | else { | |
168 | kfree(w); | |
169 | err = -EINVAL; | |
170 | } | |
171 | } else | |
172 | err = -ENOMEM; | |
7672d0b5 EP |
173 | } |
174 | break; | |
175 | } | |
176 | } | |
177 | spin_unlock_bh(&dev->cbdev->queue_lock); | |
178 | ||
acd042bb | 179 | return err; |
7672d0b5 EP |
180 | } |
181 | ||
182 | /* | |
183 | * Skb receive helper - checks skb and msg size and calls callback | |
184 | * helper. | |
185 | */ | |
186 | static int __cn_rx_skb(struct sk_buff *skb, struct nlmsghdr *nlh) | |
187 | { | |
188 | u32 pid, uid, seq, group; | |
189 | struct cn_msg *msg; | |
190 | ||
191 | pid = NETLINK_CREDS(skb)->pid; | |
192 | uid = NETLINK_CREDS(skb)->uid; | |
193 | seq = nlh->nlmsg_seq; | |
194 | group = NETLINK_CB((skb)).dst_group; | |
195 | msg = NLMSG_DATA(nlh); | |
196 | ||
197 | return cn_call_callback(msg, (void (*)(void *))kfree_skb, skb); | |
198 | } | |
199 | ||
200 | /* | |
201 | * Main netlink receiving function. | |
202 | * | |
203 | * It checks skb and netlink header sizes and calls the skb receive | |
204 | * helper with a shared skb. | |
205 | */ | |
206 | static void cn_rx_skb(struct sk_buff *__skb) | |
207 | { | |
208 | struct nlmsghdr *nlh; | |
209 | u32 len; | |
210 | int err; | |
211 | struct sk_buff *skb; | |
212 | ||
213 | skb = skb_get(__skb); | |
214 | ||
215 | if (skb->len >= NLMSG_SPACE(0)) { | |
216 | nlh = (struct nlmsghdr *)skb->data; | |
217 | ||
218 | if (nlh->nlmsg_len < sizeof(struct cn_msg) || | |
219 | skb->len < nlh->nlmsg_len || | |
220 | nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) { | |
221 | kfree_skb(skb); | |
222 | goto out; | |
223 | } | |
224 | ||
225 | len = NLMSG_ALIGN(nlh->nlmsg_len); | |
226 | if (len > skb->len) | |
227 | len = skb->len; | |
228 | ||
229 | err = __cn_rx_skb(skb, nlh); | |
230 | if (err < 0) | |
231 | kfree_skb(skb); | |
232 | } | |
233 | ||
234 | out: | |
235 | kfree_skb(__skb); | |
236 | } | |
237 | ||
238 | /* | |
239 | * Netlink socket input callback - dequeues the skbs and calls the | |
240 | * main netlink receiving function. | |
241 | */ | |
242 | static void cn_input(struct sock *sk, int len) | |
243 | { | |
244 | struct sk_buff *skb; | |
245 | ||
246 | while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) | |
247 | cn_rx_skb(skb); | |
248 | } | |
249 | ||
250 | /* | |
251 | * Notification routing. | |
252 | * | |
253 | * Gets id and checks if there are notification request for it's idx | |
254 | * and val. If there are such requests notify the listeners with the | |
255 | * given notify event. | |
256 | * | |
257 | */ | |
258 | static void cn_notify(struct cb_id *id, u32 notify_event) | |
259 | { | |
260 | struct cn_ctl_entry *ent; | |
261 | ||
262 | down(¬ify_lock); | |
263 | list_for_each_entry(ent, ¬ify_list, notify_entry) { | |
264 | int i; | |
265 | struct cn_notify_req *req; | |
266 | struct cn_ctl_msg *ctl = ent->msg; | |
267 | int idx_found, val_found; | |
268 | ||
269 | idx_found = val_found = 0; | |
270 | ||
271 | req = (struct cn_notify_req *)ctl->data; | |
272 | for (i = 0; i < ctl->idx_notify_num; ++i, ++req) { | |
273 | if (id->idx >= req->first && | |
274 | id->idx < req->first + req->range) { | |
275 | idx_found = 1; | |
276 | break; | |
277 | } | |
278 | } | |
279 | ||
280 | for (i = 0; i < ctl->val_notify_num; ++i, ++req) { | |
281 | if (id->val >= req->first && | |
282 | id->val < req->first + req->range) { | |
283 | val_found = 1; | |
284 | break; | |
285 | } | |
286 | } | |
287 | ||
288 | if (idx_found && val_found) { | |
289 | struct cn_msg m = { .ack = notify_event, }; | |
290 | ||
291 | memcpy(&m.id, id, sizeof(m.id)); | |
292 | cn_netlink_send(&m, ctl->group, GFP_KERNEL); | |
293 | } | |
294 | } | |
295 | up(¬ify_lock); | |
296 | } | |
297 | ||
298 | /* | |
299 | * Callback add routing - adds callback with given ID and name. | |
300 | * If there is registered callback with the same ID it will not be added. | |
301 | * | |
302 | * May sleep. | |
303 | */ | |
304 | int cn_add_callback(struct cb_id *id, char *name, void (*callback)(void *)) | |
305 | { | |
306 | int err; | |
307 | struct cn_dev *dev = &cdev; | |
7672d0b5 | 308 | |
acd042bb EP |
309 | err = cn_queue_add_callback(dev->cbdev, name, id, callback); |
310 | if (err) | |
7672d0b5 | 311 | return err; |
7672d0b5 EP |
312 | |
313 | cn_notify(id, 0); | |
314 | ||
315 | return 0; | |
316 | } | |
317 | ||
318 | /* | |
319 | * Callback remove routing - removes callback | |
320 | * with given ID. | |
321 | * If there is no registered callback with given | |
322 | * ID nothing happens. | |
323 | * | |
324 | * May sleep while waiting for reference counter to become zero. | |
325 | */ | |
326 | void cn_del_callback(struct cb_id *id) | |
327 | { | |
328 | struct cn_dev *dev = &cdev; | |
329 | ||
330 | cn_queue_del_callback(dev->cbdev, id); | |
331 | cn_notify(id, 1); | |
332 | } | |
333 | ||
334 | /* | |
335 | * Checks two connector's control messages to be the same. | |
336 | * Returns 1 if they are the same or if the first one is corrupted. | |
337 | */ | |
338 | static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2) | |
339 | { | |
340 | int i; | |
341 | struct cn_notify_req *req1, *req2; | |
342 | ||
343 | if (m1->idx_notify_num != m2->idx_notify_num) | |
344 | return 0; | |
345 | ||
346 | if (m1->val_notify_num != m2->val_notify_num) | |
347 | return 0; | |
348 | ||
349 | if (m1->len != m2->len) | |
350 | return 0; | |
351 | ||
352 | if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) != | |
353 | m1->len) | |
354 | return 1; | |
355 | ||
356 | req1 = (struct cn_notify_req *)m1->data; | |
357 | req2 = (struct cn_notify_req *)m2->data; | |
358 | ||
359 | for (i = 0; i < m1->idx_notify_num; ++i) { | |
360 | if (req1->first != req2->first || req1->range != req2->range) | |
361 | return 0; | |
362 | req1++; | |
363 | req2++; | |
364 | } | |
365 | ||
366 | for (i = 0; i < m1->val_notify_num; ++i) { | |
367 | if (req1->first != req2->first || req1->range != req2->range) | |
368 | return 0; | |
369 | req1++; | |
370 | req2++; | |
371 | } | |
372 | ||
373 | return 1; | |
374 | } | |
375 | ||
376 | /* | |
377 | * Main connector device's callback. | |
378 | * | |
379 | * Used for notification of a request's processing. | |
380 | */ | |
381 | static void cn_callback(void *data) | |
382 | { | |
383 | struct cn_msg *msg = data; | |
384 | struct cn_ctl_msg *ctl; | |
385 | struct cn_ctl_entry *ent; | |
386 | u32 size; | |
387 | ||
388 | if (msg->len < sizeof(*ctl)) | |
389 | return; | |
390 | ||
391 | ctl = (struct cn_ctl_msg *)msg->data; | |
392 | ||
393 | size = (sizeof(*ctl) + ((ctl->idx_notify_num + | |
394 | ctl->val_notify_num) * | |
395 | sizeof(struct cn_notify_req))); | |
396 | ||
397 | if (msg->len != size) | |
398 | return; | |
399 | ||
400 | if (ctl->len + sizeof(*ctl) != msg->len) | |
401 | return; | |
402 | ||
403 | /* | |
404 | * Remove notification. | |
405 | */ | |
406 | if (ctl->group == 0) { | |
407 | struct cn_ctl_entry *n; | |
408 | ||
409 | down(¬ify_lock); | |
410 | list_for_each_entry_safe(ent, n, ¬ify_list, notify_entry) { | |
411 | if (cn_ctl_msg_equals(ent->msg, ctl)) { | |
412 | list_del(&ent->notify_entry); | |
413 | kfree(ent); | |
414 | } | |
415 | } | |
416 | up(¬ify_lock); | |
417 | ||
418 | return; | |
419 | } | |
420 | ||
421 | size += sizeof(*ent); | |
422 | ||
423 | ent = kzalloc(size, GFP_KERNEL); | |
424 | if (!ent) | |
425 | return; | |
426 | ||
427 | ent->msg = (struct cn_ctl_msg *)(ent + 1); | |
428 | ||
429 | memcpy(ent->msg, ctl, size - sizeof(*ent)); | |
430 | ||
431 | down(¬ify_lock); | |
432 | list_add(&ent->notify_entry, ¬ify_list); | |
433 | up(¬ify_lock); | |
434 | } | |
435 | ||
436 | static int __init cn_init(void) | |
437 | { | |
438 | struct cn_dev *dev = &cdev; | |
439 | int err; | |
440 | ||
441 | dev->input = cn_input; | |
442 | dev->id.idx = cn_idx; | |
443 | dev->id.val = cn_val; | |
444 | ||
445 | dev->nls = netlink_kernel_create(NETLINK_CONNECTOR, | |
446 | CN_NETLINK_USERS + 0xf, | |
447 | dev->input, THIS_MODULE); | |
448 | if (!dev->nls) | |
449 | return -EIO; | |
450 | ||
451 | dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls); | |
452 | if (!dev->cbdev) { | |
453 | if (dev->nls->sk_socket) | |
454 | sock_release(dev->nls->sk_socket); | |
455 | return -EINVAL; | |
456 | } | |
457 | ||
458 | err = cn_add_callback(&dev->id, "connector", &cn_callback); | |
459 | if (err) { | |
460 | cn_queue_free_dev(dev->cbdev); | |
461 | if (dev->nls->sk_socket) | |
462 | sock_release(dev->nls->sk_socket); | |
463 | return -EINVAL; | |
464 | } | |
465 | ||
466 | cn_already_initialized = 1; | |
467 | ||
468 | return 0; | |
469 | } | |
470 | ||
471 | static void __exit cn_fini(void) | |
472 | { | |
473 | struct cn_dev *dev = &cdev; | |
474 | ||
475 | cn_already_initialized = 0; | |
476 | ||
477 | cn_del_callback(&dev->id); | |
478 | cn_queue_free_dev(dev->cbdev); | |
479 | if (dev->nls->sk_socket) | |
480 | sock_release(dev->nls->sk_socket); | |
481 | } | |
482 | ||
483 | module_init(cn_init); | |
484 | module_exit(cn_fini); | |
485 | ||
486 | EXPORT_SYMBOL_GPL(cn_add_callback); | |
487 | EXPORT_SYMBOL_GPL(cn_del_callback); | |
488 | EXPORT_SYMBOL_GPL(cn_netlink_send); |