aboutsummaryrefslogtreecommitdiff
path: root/drivers/connector/connector.c
blob: 3f45669f5d760b1ec5fa104eea00c0a25c114ef4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
/*
 * 	connector.c
 *
 * 2004-2005 Copyright (c) Evgeniy Polyakov <johnpol@2ka.mipt.ru>
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/moduleparam.h>
#include <linux/connector.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/spinlock.h>

#include <net/sock.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>");
MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");

static u32 cn_idx = CN_IDX_CONNECTOR;
static u32 cn_val = CN_VAL_CONNECTOR;

module_param(cn_idx, uint, 0);
module_param(cn_val, uint, 0);
MODULE_PARM_DESC(cn_idx, "Connector's main device idx.");
MODULE_PARM_DESC(cn_val, "Connector's main device val.");

static DEFINE_MUTEX(notify_lock);
static LIST_HEAD(notify_list);

static struct cn_dev cdev;

static int cn_already_initialized;

/*
 * msg->seq and msg->ack are used to determine message genealogy.
 * When someone sends message it puts there locally unique sequence
 * and random acknowledge numbers.  Sequence number may be copied into
 * nlmsghdr->nlmsg_seq too.
 *
 * Sequence number is incremented with each message to be sent.
 *
 * If we expect reply to our message then the sequence number in
 * received message MUST be the same as in original message, and
 * acknowledge number MUST be the same + 1.
 *
 * If we receive a message and its sequence number is not equal to the
 * one we are expecting then it is a new message.
 *
 * If we receive a message and its sequence number is the same as one
 * we are expecting but it's acknowledgement number is not equal to
 * the acknowledgement number in the original message + 1, then it is
 * a new message.
 *
 */
int cn_netlink_send(struct cn_msg *msg, u32 __group, gfp_t gfp_mask)
{
	struct cn_callback_entry *__cbq;
	unsigned int size;
	struct sk_buff *skb;
	struct nlmsghdr *nlh;
	struct cn_msg *data;
	struct cn_dev *dev = &cdev;
	u32 group = 0;
	int found = 0;

	if (!__group) {
		spin_lock_bh(&dev->cbdev->queue_lock);
		list_for_each_entry(__cbq, &dev->cbdev->queue_list,
				    callback_entry) {
			if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
				found = 1;
				group = __cbq->group;
				break;
			}
		}
		spin_unlock_bh(&dev->cbdev->queue_lock);

		if (!found)
			return -ENODEV;
	} else {
		group = __group;
	}

	if (!netlink_has_listeners(dev->nls, group))
		return -ESRCH;

	size = NLMSG_SPACE(sizeof(*msg) + msg->len);

	skb = alloc_skb(size, gfp_mask);
	if (!skb)
		return -ENOMEM;

	nlh = NLMSG_PUT(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh));

	data = NLMSG_DATA(nlh);

	memcpy(data, msg, sizeof(*data) + msg->len);

	NETLINK_CB(skb).dst_group = group;

	return netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);

nlmsg_failure:
	kfree_skb(skb);
	return -EINVAL;
}
EXPORT_SYMBOL_GPL(cn_netlink_send);

/*
 * Callback helper - queues work and setup destructor for given data.
 */
static int cn_call_callback(struct cn_msg *msg, void (*destruct_data)(void *), void *data)
{
	struct cn_callback_entry *__cbq, *__new_cbq;
	struct cn_dev *dev = &cdev;
	int err = -ENODEV;

	spin_lock_bh(&dev->cbdev->queue_lock);
	list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) {
		if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
			if (likely(!work_pending(&__cbq->work) &&
					__cbq->data.ddata == NULL)) {
				__cbq->data.callback_priv = msg;

				__cbq->data.ddata = data;
				__cbq->data.destruct_data = destruct_data;

				if (queue_cn_work(__cbq, &__cbq->work))
					err = 0;
				else
					err = -EINVAL;
			} else {
				struct cn_callback_data *d;

				err = -ENOMEM;
				__new_cbq = kzalloc(sizeof(struct cn_callback_entry), GFP_ATOMIC);
				if (__new_cbq) {
					d = &__new_cbq->data;
					d->callback_priv = msg;
					d->callback = __cbq->data.callback;
					d->ddata = data;
					d->destruct_data = destruct_data;
					d->free = __new_cbq;

					__new_cbq->pdev = __cbq->pdev;

					INIT_WORK(&__new_cbq->work,
							&cn_queue_wrapper);

					if (queue_cn_work(__new_cbq,
						    &__new_cbq->work))
						err = 0;
					else {
						kfree(__new_cbq);
						err = -EINVAL;
					}
				}
			}
			break;
		}
	}
	spin_unlock_bh(&dev->cbdev->queue_lock);

	return err;
}

/*
 * Main netlink receiving function.
 *
 * It checks skb, netlink header and msg sizes, and calls callback helper.
 */
static void cn_rx_skb(struct sk_buff *__skb)
{
	struct cn_msg *msg;
	struct nlmsghdr *nlh;
	int err;
	struct sk_buff *skb;

	skb = skb_get(__skb);

	if (skb->len >= NLMSG_SPACE(0)) {
		nlh = nlmsg_hdr(skb);

		if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
		    skb->len < nlh->nlmsg_len ||
		    nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
			kfree_skb(skb);
			return;
		}

		msg = NLMSG_DATA(nlh);
		err = cn_call_callback(msg, (void (*)(void *))kfree_skb, skb);
		if (err < 0)
			kfree_skb(skb);
	}
}

/*
 * Notification routing.
 *
 * Gets id and checks if there are notification request for it's idx
 * and val.  If there are such requests notify the listeners with the
 * given notify event.
 *
 */
static void cn_notify(struct cb_id *id, u32 notify_event)
{
	struct cn_ctl_entry *ent;

	mutex_lock(&notify_lock);
	list_for_each_entry(ent, &notify_list, notify_entry) {
		int i;
		struct cn_notify_req *req;
		struct cn_ctl_msg *ctl = ent->msg;
		int idx_found, val_found;

		idx_found = val_found = 0;

		req = (struct cn_notify_req *)ctl->data;
		for (i = 0; i < ctl->idx_notify_num; ++i, ++req) {
			if (id->idx >= req->first &&
					id->idx < req->first + req->range) {
				idx_found = 1;
				break;
			}
		}

		for (i = 0; i < ctl->val_notify_num; ++i, ++req) {
			if (id->val >= req->first &&
					id->val < req->first + req->range) {
				val_found = 1;
				break;
			}
		}

		if (idx_found && val_found) {
			struct cn_msg m = { .ack = notify_event, };

			memcpy(&m.id, id, sizeof(m.id));
			cn_netlink_send(&m, ctl->group, GFP_KERNEL);
		}
	}
	mutex_unlock(&notify_lock);
}

/*
 * Callback add routing - adds callback with given ID and name.
 * If there is registered callback with the same ID it will not be added.
 *
 * May sleep.
 */
int cn_add_callback(struct cb_id *id, char *name,
		    void (*callback)(struct cn_msg *))
{
	int err;
	struct cn_dev *dev = &cdev;

	if (!cn_already_initialized)
		return -EAGAIN;

	err = cn_queue_add_callback(dev->cbdev, name, id, callback);
	if (err)
		return err;

	cn_notify(id, 0);

	return 0;
}
EXPORT_SYMBOL_GPL(cn_add_callback);

/*
 * Callback remove routing - removes callback
 * with given ID.
 * If there is no registered callback with given
 * ID nothing happens.
 *
 * May sleep while waiting for reference counter to become zero.
 */
void cn_del_callback(struct cb_id *id)
{
	struct cn_dev *dev = &cdev;

	cn_queue_del_callback(dev->cbdev, id);
	cn_notify(id, 1);
}
EXPORT_SYMBOL_GPL(cn_del_callback);

/*
 * Checks two connector's control messages to be the same.
 * Returns 1 if they are the same or if the first one is corrupted.
 */
static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2)
{
	int i;
	struct cn_notify_req *req1, *req2;

	if (m1->idx_notify_num != m2->idx_notify_num)
		return 0;

	if (m1->val_notify_num != m2->val_notify_num)
		return 0;

	if (m1->len != m2->len)
		return 0;

	if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) !=
	    m1->len)
		return 1;

	req1 = (struct cn_notify_req *)m1->data;
	req2 = (struct cn_notify_req *)m2->data;

	for (i = 0; i < m1->idx_notify_num; ++i) {
		if (req1->first != req2->first || req1->range != req2->range)
			return 0;
		req1++;
		req2++;
	}

	for (i = 0; i < m1->val_notify_num; ++i) {
		if (req1->first != req2->first || req1->range != req2->range)
			return 0;
		req1++;
		req2++;
	}

	return 1;
}

/*
 * Main connector device's callback.
 *
 * Used for notification of a request's processing.
 */
static void cn_callback(struct cn_msg *msg)
{
	struct cn_ctl_msg *ctl;
	struct cn_ctl_entry *ent;
	u32 size;

	if (msg->len < sizeof(*ctl))
		return;

	ctl = (struct cn_ctl_msg *)msg->data;

	size = (sizeof(*ctl) + ((ctl->idx_notify_num +
				 ctl->val_notify_num) *
				sizeof(struct cn_notify_req)));

	if (msg->len != size)
		return;

	if (ctl->len + sizeof(*ctl) != msg->len)
		return;

	/*
	 * Remove notification.
	 */
	if (ctl->group == 0) {
		struct cn_ctl_entry *n;

		mutex_lock(&notify_lock);
		list_for_each_entry_safe(ent, n, &notify_list, notify_entry) {
			if (cn_ctl_msg_equals(ent->msg, ctl)) {
				list_del(&ent->notify_entry);
				kfree(ent);
			}
		}
		mutex_unlock(&notify_lock);

		return;
	}

	size += sizeof(*ent);

	ent = kzalloc(size, GFP_KERNEL);
	if (!ent)
		return;

	ent->msg = (struct cn_ctl_msg *)(ent + 1);

	memcpy(ent->msg, ctl, size - sizeof(*ent));

	mutex_lock(&notify_lock);
	list_add(&ent->notify_entry, &notify_list);
	mutex_unlock(&notify_lock);
}

static int cn_proc_show(struct seq_file *m, void *v)
{
	struct cn_queue_dev *dev = cdev.cbdev;
	struct cn_callback_entry *cbq;

	seq_printf(m, "Name            ID\n");

	spin_lock_bh(&dev->queue_lock);

	list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
		seq_printf(m, "%-15s %u:%u\n",
			   cbq->id.name,
			   cbq->id.id.idx,
			   cbq->id.id.val);
	}

	spin_unlock_bh(&dev->queue_lock);

	return 0;
}

static int cn_proc_open(struct inode *inode, struct file *file)
{
	return single_open(file, cn_proc_show, NULL);
}

static const struct file_operations cn_file_ops = {
	.owner   = THIS_MODULE,
	.open    = cn_proc_open,
	.read    = seq_read,
	.llseek  = seq_lseek,
	.release = single_release
};

static int __devinit cn_init(void)
{
	struct cn_dev *dev = &cdev;
	int err;

	dev->input = cn_rx_skb;
	dev->id.idx = cn_idx;
	dev->id.val = cn_val;

	dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR,
					 CN_NETLINK_USERS + 0xf,
					 dev->input, NULL, THIS_MODULE);
	if (!dev->nls)
		return -EIO;

	dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
	if (!dev->cbdev) {
		netlink_kernel_release(dev->nls);
		return -EINVAL;
	}

	cn_already_initialized = 1;

	err = cn_add_callback(&dev->id, "connector", &cn_callback);
	if (err) {
		cn_already_initialized = 0;
		cn_queue_free_dev(dev->cbdev);
		netlink_kernel_release(dev->nls);
		return -EINVAL;
	}

	proc_net_fops_create(&init_net, "connector", S_IRUGO, &cn_file_ops);

	return 0;
}

static void __devexit cn_fini(void)
{
	struct cn_dev *dev = &cdev;

	cn_already_initialized = 0;

	proc_net_remove(&init_net, "connector");

	cn_del_callback(&dev->id);
	cn_queue_free_dev(dev->cbdev);
	netlink_kernel_release(dev->nls);
}

subsys_initcall(cn_init);
module_exit(cn_fini);