summaryrefslogtreecommitdiffstats
path: root/drivers/usb/wusbcore/security.c
blob: 8c9421b69da00adb560dc7d18719591065c0f8d8 (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
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
/*
 * Wireless USB Host Controller
 * Security support: encryption enablement, etc
 *
 * Copyright (C) 2006 Intel Corporation
 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 *
 * FIXME: docs
 */
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/usb/ch9.h>
#include <linux/random.h>
#include <linux/export.h>
#include "wusbhc.h"

static void wusbhc_gtk_rekey_work(struct work_struct *work);

int wusbhc_sec_create(struct wusbhc *wusbhc)
{
	/*
	 * WQ is singlethread because we need to serialize rekey operations.
	 * Use a separate workqueue for security operations instead of the
	 * wusbd workqueue because security operations may need to communicate
	 * directly with downstream wireless devices using synchronous URBs.
	 * If a device is not responding, this could block other host
	 * controller operations.
	 */
	wusbhc->wq_security = create_singlethread_workqueue("wusbd_security");
	if (wusbhc->wq_security == NULL) {
		pr_err("WUSB-core: Cannot create wusbd_security workqueue\n");
		return -ENOMEM;
	}

	wusbhc->gtk.descr.bLength = sizeof(wusbhc->gtk.descr) +
		sizeof(wusbhc->gtk.data);
	wusbhc->gtk.descr.bDescriptorType = USB_DT_KEY;
	wusbhc->gtk.descr.bReserved = 0;
	wusbhc->gtk_index = 0;

	INIT_WORK(&wusbhc->gtk_rekey_work, wusbhc_gtk_rekey_work);

	return 0;
}


/* Called when the HC is destroyed */
void wusbhc_sec_destroy(struct wusbhc *wusbhc)
{
	destroy_workqueue(wusbhc->wq_security);
}


/**
 * wusbhc_next_tkid - generate a new, currently unused, TKID
 * @wusbhc:   the WUSB host controller
 * @wusb_dev: the device whose PTK the TKID is for
 *            (or NULL for a TKID for a GTK)
 *
 * The generated TKID consists of two parts: the device's authenticated
 * address (or 0 or a GTK); and an incrementing number.  This ensures
 * that TKIDs cannot be shared between devices and by the time the
 * incrementing number wraps around the older TKIDs will no longer be
 * in use (a maximum of two keys may be active at any one time).
 */
static u32 wusbhc_next_tkid(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
{
	u32 *tkid;
	u32 addr;

	if (wusb_dev == NULL) {
		tkid = &wusbhc->gtk_tkid;
		addr = 0;
	} else {
		tkid = &wusb_port_by_idx(wusbhc, wusb_dev->port_idx)->ptk_tkid;
		addr = wusb_dev->addr & 0x7f;
	}

	*tkid = (addr << 8) | ((*tkid + 1) & 0xff);

	return *tkid;
}

static void wusbhc_generate_gtk(struct wusbhc *wusbhc)
{
	const size_t key_size = sizeof(wusbhc->gtk.data);
	u32 tkid;

	tkid = wusbhc_next_tkid(wusbhc, NULL);

	wusbhc->gtk.descr.tTKID[0] = (tkid >>  0) & 0xff;
	wusbhc->gtk.descr.tTKID[1] = (tkid >>  8) & 0xff;
	wusbhc->gtk.descr.tTKID[2] = (tkid >> 16) & 0xff;

	get_random_bytes(wusbhc->gtk.descr.bKeyData, key_size);
}

/**
 * wusbhc_sec_start - start the security management process
 * @wusbhc: the WUSB host controller
 *
 * Generate and set an initial GTK on the host controller.
 *
 * Called when the HC is started.
 */
int wusbhc_sec_start(struct wusbhc *wusbhc)
{
	const size_t key_size = sizeof(wusbhc->gtk.data);
	int result;

	wusbhc_generate_gtk(wusbhc);

	result = wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid,
				&wusbhc->gtk.descr.bKeyData, key_size);
	if (result < 0)
		dev_err(wusbhc->dev, "cannot set GTK for the host: %d\n",
			result);

	return result;
}

/**
 * wusbhc_sec_stop - stop the security management process
 * @wusbhc: the WUSB host controller
 *
 * Wait for any pending GTK rekeys to stop.
 */
void wusbhc_sec_stop(struct wusbhc *wusbhc)
{
	cancel_work_sync(&wusbhc->gtk_rekey_work);
}


/** @returns encryption type name */
const char *wusb_et_name(u8 x)
{
	switch (x) {
	case USB_ENC_TYPE_UNSECURE:	return "unsecure";
	case USB_ENC_TYPE_WIRED:	return "wired";
	case USB_ENC_TYPE_CCM_1:	return "CCM-1";
	case USB_ENC_TYPE_RSA_1:	return "RSA-1";
	default:			return "unknown";
	}
}
EXPORT_SYMBOL_GPL(wusb_et_name);

/*
 * Set the device encryption method
 *
 * We tell the device which encryption method to use; we do this when
 * setting up the device's security.
 */
static int wusb_dev_set_encryption(struct usb_device *usb_dev, int value)
{
	int result;
	struct device *dev = &usb_dev->dev;
	struct wusb_dev *wusb_dev = usb_dev->wusb_dev;

	if (value) {
		value = wusb_dev->ccm1_etd.bEncryptionValue;
	} else {
		/* FIXME: should be wusb_dev->etd[UNSECURE].bEncryptionValue */
		value = 0;
	}
	/* Set device's */
	result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
			USB_REQ_SET_ENCRYPTION,
			USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
			value, 0, NULL, 0, USB_CTRL_SET_TIMEOUT);
	if (result < 0)
		dev_err(dev, "Can't set device's WUSB encryption to "
			"%s (value %d): %d\n",
			wusb_et_name(wusb_dev->ccm1_etd.bEncryptionType),
			wusb_dev->ccm1_etd.bEncryptionValue,  result);
	return result;
}

/*
 * Set the GTK to be used by a device.
 *
 * The device must be authenticated.
 */
static int wusb_dev_set_gtk(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
{
	struct usb_device *usb_dev = wusb_dev->usb_dev;
	u8 key_index = wusb_key_index(wusbhc->gtk_index,
		WUSB_KEY_INDEX_TYPE_GTK, WUSB_KEY_INDEX_ORIGINATOR_HOST);

	return usb_control_msg(
		usb_dev, usb_sndctrlpipe(usb_dev, 0),
		USB_REQ_SET_DESCRIPTOR,
		USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
		USB_DT_KEY << 8 | key_index, 0,
		&wusbhc->gtk.descr, wusbhc->gtk.descr.bLength,
		USB_CTRL_SET_TIMEOUT);
}


/* FIXME: prototype for adding security */
int wusb_dev_sec_add(struct wusbhc *wusbhc,
		     struct usb_device *usb_dev, struct wusb_dev *wusb_dev)
{
	int result, bytes, secd_size;
	struct device *dev = &usb_dev->dev;
	struct usb_security_descriptor *secd, *new_secd;
	const struct usb_encryption_descriptor *etd, *ccm1_etd = NULL;
	const void *itr, *top;
	char buf[64];

	secd = kmalloc(sizeof(*secd), GFP_KERNEL);
	if (secd == NULL) {
		result = -ENOMEM;
		goto out;
	}

	result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
				    0, secd, sizeof(*secd));
	if (result < sizeof(*secd)) {
		dev_err(dev, "Can't read security descriptor or "
			"not enough data: %d\n", result);
		goto out;
	}
	secd_size = le16_to_cpu(secd->wTotalLength);
	new_secd = krealloc(secd, secd_size, GFP_KERNEL);
	if (new_secd == NULL) {
		dev_err(dev,
			"Can't allocate space for security descriptors\n");
		goto out;
	}
	secd = new_secd;
	result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
				    0, secd, secd_size);
	if (result < secd_size) {
		dev_err(dev, "Can't read security descriptor or "
			"not enough data: %d\n", result);
		goto out;
	}
	bytes = 0;
	itr = &secd[1];
	top = (void *)secd + result;
	while (itr < top) {
		etd = itr;
		if (top - itr < sizeof(*etd)) {
			dev_err(dev, "BUG: bad device security descriptor; "
				"not enough data (%zu vs %zu bytes left)\n",
				top - itr, sizeof(*etd));
			break;
		}
		if (etd->bLength < sizeof(*etd)) {
			dev_err(dev, "BUG: bad device encryption descriptor; "
				"descriptor is too short "
				"(%u vs %zu needed)\n",
				etd->bLength, sizeof(*etd));
			break;
		}
		itr += etd->bLength;
		bytes += snprintf(buf + bytes, sizeof(buf) - bytes,
				  "%s (0x%02x/%02x) ",
				  wusb_et_name(etd->bEncryptionType),
				  etd->bEncryptionValue, etd->bAuthKeyIndex);
		if (etd->bEncryptionType == USB_ENC_TYPE_CCM_1)
			ccm1_etd = etd;
	}
	/* This code only supports CCM1 as of now. */
	/* FIXME: user has to choose which sec mode to use?
	 * In theory we want CCM */
	if (ccm1_etd == NULL) {
		dev_err(dev, "WUSB device doesn't support CCM1 encryption, "
			"can't use!\n");
		result = -EINVAL;
		goto out;
	}
	wusb_dev->ccm1_etd = *ccm1_etd;
	dev_dbg(dev, "supported encryption: %s; using %s (0x%02x/%02x)\n",
		buf, wusb_et_name(ccm1_etd->bEncryptionType),
		ccm1_etd->bEncryptionValue, ccm1_etd->bAuthKeyIndex);
	result = 0;
out:
	kfree(secd);
	return result;
}

void wusb_dev_sec_rm(struct wusb_dev *wusb_dev)
{
	/* Nothing so far */
}

/**
 * Update the address of an unauthenticated WUSB device
 *
 * Once we have successfully authenticated, we take it to addr0 state
 * and then to a normal address.
 *
 * Before the device's address (as known by it) was usb_dev->devnum |
 * 0x80 (unauthenticated address). With this we update it to usb_dev->devnum.
 */
int wusb_dev_update_address(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
{
	int result = -ENOMEM;
	struct usb_device *usb_dev = wusb_dev->usb_dev;
	struct device *dev = &usb_dev->dev;
	u8 new_address = wusb_dev->addr & 0x7F;

	/* Set address 0 */
	result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
			USB_REQ_SET_ADDRESS,
			USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
			 0, 0, NULL, 0, USB_CTRL_SET_TIMEOUT);
	if (result < 0) {
		dev_err(dev, "auth failed: can't set address 0: %d\n",
			result);
		goto error_addr0;
	}
	result = wusb_set_dev_addr(wusbhc, wusb_dev, 0);
	if (result < 0)
		goto error_addr0;
	usb_set_device_state(usb_dev, USB_STATE_DEFAULT);
	usb_ep0_reinit(usb_dev);

	/* Set new (authenticated) address. */
	result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
			USB_REQ_SET_ADDRESS,
			USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
			new_address, 0, NULL, 0,
			USB_CTRL_SET_TIMEOUT);
	if (result < 0) {
		dev_err(dev, "auth failed: can't set address %u: %d\n",
			new_address, result);
		goto error_addr;
	}
	result = wusb_set_dev_addr(wusbhc, wusb_dev, new_address);
	if (result < 0)
		goto error_addr;
	usb_set_device_state(usb_dev, USB_STATE_ADDRESS);
	usb_ep0_reinit(usb_dev);
	usb_dev->authenticated = 1;
error_addr:
error_addr0:
	return result;
}

/*
 *
 *
 */
/* FIXME: split and cleanup */
int wusb_dev_4way_handshake(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev,
			    struct wusb_ckhdid *ck)
{
	int result = -ENOMEM;
	struct usb_device *usb_dev = wusb_dev->usb_dev;
	struct device *dev = &usb_dev->dev;
	u32 tkid;
	__le32 tkid_le;
	struct usb_handshake *hs;
	struct aes_ccm_nonce ccm_n;
	u8 mic[8];
	struct wusb_keydvt_in keydvt_in;
	struct wusb_keydvt_out keydvt_out;

	hs = kcalloc(3, sizeof(hs[0]), GFP_KERNEL);
	if (!hs)
		goto error_kzalloc;

	/* We need to turn encryption before beginning the 4way
	 * hshake (WUSB1.0[.3.2.2]) */
	result = wusb_dev_set_encryption(usb_dev, 1);
	if (result < 0)
		goto error_dev_set_encryption;

	tkid = wusbhc_next_tkid(wusbhc, wusb_dev);
	tkid_le = cpu_to_le32(tkid);

	hs[0].bMessageNumber = 1;
	hs[0].bStatus = 0;
	memcpy(hs[0].tTKID, &tkid_le, sizeof(hs[0].tTKID));
	hs[0].bReserved = 0;
	memcpy(hs[0].CDID, &wusb_dev->cdid, sizeof(hs[0].CDID));
	get_random_bytes(&hs[0].nonce, sizeof(hs[0].nonce));
	memset(hs[0].MIC, 0, sizeof(hs[0].MIC)); /* Per WUSB1.0[T7-22] */

	result = usb_control_msg(
		usb_dev, usb_sndctrlpipe(usb_dev, 0),
		USB_REQ_SET_HANDSHAKE,
		USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
		1, 0, &hs[0], sizeof(hs[0]), USB_CTRL_SET_TIMEOUT);
	if (result < 0) {
		dev_err(dev, "Handshake1: request failed: %d\n", result);
		goto error_hs1;
	}

	/* Handshake 2, from the device -- need to verify fields */
	result = usb_control_msg(
		usb_dev, usb_rcvctrlpipe(usb_dev, 0),
		USB_REQ_GET_HANDSHAKE,
		USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
		2, 0, &hs[1], sizeof(hs[1]), USB_CTRL_GET_TIMEOUT);
	if (result < 0) {
		dev_err(dev, "Handshake2: request failed: %d\n", result);
		goto error_hs2;
	}

	result = -EINVAL;
	if (hs[1].bMessageNumber != 2) {
		dev_err(dev, "Handshake2 failed: bad message number %u\n",
			hs[1].bMessageNumber);
		goto error_hs2;
	}
	if (hs[1].bStatus != 0) {
		dev_err(dev, "Handshake2 failed: bad status %u\n",
			hs[1].bStatus);
		goto error_hs2;
	}
	if (memcmp(hs[0].tTKID, hs[1].tTKID, sizeof(hs[0].tTKID))) {
		dev_err(dev, "Handshake2 failed: TKID mismatch "
			"(#1 0x%02x%02x%02x vs #2 0x%02x%02x%02x)\n",
			hs[0].tTKID[0], hs[0].tTKID[1], hs[0].tTKID[2],
			hs[1].tTKID[0], hs[1].tTKID[1], hs[1].tTKID[2]);
		goto error_hs2;
	}
	if (memcmp(hs[0].CDID, hs[1].CDID, sizeof(hs[0].CDID))) {
		dev_err(dev, "Handshake2 failed: CDID mismatch\n");
		goto error_hs2;
	}

	/* Setup the CCM nonce */
	memset(&ccm_n.sfn, 0, sizeof(ccm_n.sfn)); /* Per WUSB1.0[6.5.2] */
	memcpy(ccm_n.tkid, &tkid_le, sizeof(ccm_n.tkid));
	ccm_n.src_addr = wusbhc->uwb_rc->uwb_dev.dev_addr;
	ccm_n.dest_addr.data[0] = wusb_dev->addr;
	ccm_n.dest_addr.data[1] = 0;

	/* Derive the KCK and PTK from CK, the CCM, H and D nonces */
	memcpy(keydvt_in.hnonce, hs[0].nonce, sizeof(keydvt_in.hnonce));
	memcpy(keydvt_in.dnonce, hs[1].nonce, sizeof(keydvt_in.dnonce));
	result = wusb_key_derive(&keydvt_out, ck->data, &ccm_n, &keydvt_in);
	if (result < 0) {
		dev_err(dev, "Handshake2 failed: cannot derive keys: %d\n",
			result);
		goto error_hs2;
	}

	/* Compute MIC and verify it */
	result = wusb_oob_mic(mic, keydvt_out.kck, &ccm_n, &hs[1]);
	if (result < 0) {
		dev_err(dev, "Handshake2 failed: cannot compute MIC: %d\n",
			result);
		goto error_hs2;
	}

	if (memcmp(hs[1].MIC, mic, sizeof(hs[1].MIC))) {
		dev_err(dev, "Handshake2 failed: MIC mismatch\n");
		goto error_hs2;
	}

	/* Send Handshake3 */
	hs[2].bMessageNumber = 3;
	hs[2].bStatus = 0;
	memcpy(hs[2].tTKID, &tkid_le, sizeof(hs[2].tTKID));
	hs[2].bReserved = 0;
	memcpy(hs[2].CDID, &wusb_dev->cdid, sizeof(hs[2].CDID));
	memcpy(hs[2].nonce, hs[0].nonce, sizeof(hs[2].nonce));
	result = wusb_oob_mic(hs[2].MIC, keydvt_out.kck, &ccm_n, &hs[2]);
	if (result < 0) {
		dev_err(dev, "Handshake3 failed: cannot compute MIC: %d\n",
			result);
		goto error_hs2;
	}

	result = usb_control_msg(
		usb_dev, usb_sndctrlpipe(usb_dev, 0),
		USB_REQ_SET_HANDSHAKE,
		USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
		3, 0, &hs[2], sizeof(hs[2]), USB_CTRL_SET_TIMEOUT);
	if (result < 0) {
		dev_err(dev, "Handshake3: request failed: %d\n", result);
		goto error_hs3;
	}

	result = wusbhc->set_ptk(wusbhc, wusb_dev->port_idx, tkid,
				 keydvt_out.ptk, sizeof(keydvt_out.ptk));
	if (result < 0)
		goto error_wusbhc_set_ptk;

	result = wusb_dev_set_gtk(wusbhc, wusb_dev);
	if (result < 0) {
		dev_err(dev, "Set GTK for device: request failed: %d\n",
			result);
		goto error_wusbhc_set_gtk;
	}

	/* Update the device's address from unauth to auth */
	if (usb_dev->authenticated == 0) {
		result = wusb_dev_update_address(wusbhc, wusb_dev);
		if (result < 0)
			goto error_dev_update_address;
	}
	result = 0;
	dev_info(dev, "device authenticated\n");

error_dev_update_address:
error_wusbhc_set_gtk:
error_wusbhc_set_ptk:
error_hs3:
error_hs2:
error_hs1:
	memset(hs, 0, 3*sizeof(hs[0]));
	memzero_explicit(&keydvt_out, sizeof(keydvt_out));
	memzero_explicit(&keydvt_in, sizeof(keydvt_in));
	memzero_explicit(&ccm_n, sizeof(ccm_n));
	memzero_explicit(mic, sizeof(mic));
	if (result < 0)
		wusb_dev_set_encryption(usb_dev, 0);
error_dev_set_encryption:
	kfree(hs);
error_kzalloc:
	return result;
}

/*
 * Once all connected and authenticated devices have received the new
 * GTK, switch the host to using it.
 */
static void wusbhc_gtk_rekey_work(struct work_struct *work)
{
	struct wusbhc *wusbhc = container_of(work,
					struct wusbhc, gtk_rekey_work);
	size_t key_size = sizeof(wusbhc->gtk.data);
	int port_idx;
	struct wusb_dev *wusb_dev, *wusb_dev_next;
	LIST_HEAD(rekey_list);

	mutex_lock(&wusbhc->mutex);
	/* generate the new key */
	wusbhc_generate_gtk(wusbhc);
	/* roll the gtk index. */
	wusbhc->gtk_index = (wusbhc->gtk_index + 1) % (WUSB_KEY_INDEX_MAX + 1);
	/*
	 * Save all connected devices on a list while holding wusbhc->mutex and
	 * take a reference to each one.  Then submit the set key request to
	 * them after releasing the lock in order to avoid a deadlock.
	 */
	for (port_idx = 0; port_idx < wusbhc->ports_max; port_idx++) {
		wusb_dev = wusbhc->port[port_idx].wusb_dev;
		if (!wusb_dev || !wusb_dev->usb_dev
			|| !wusb_dev->usb_dev->authenticated)
			continue;

		wusb_dev_get(wusb_dev);
		list_add_tail(&wusb_dev->rekey_node, &rekey_list);
	}
	mutex_unlock(&wusbhc->mutex);

	/* Submit the rekey requests without holding wusbhc->mutex. */
	list_for_each_entry_safe(wusb_dev, wusb_dev_next, &rekey_list,
		rekey_node) {
		list_del_init(&wusb_dev->rekey_node);
		dev_dbg(&wusb_dev->usb_dev->dev,
			"%s: rekey device at port %d\n",
			__func__, wusb_dev->port_idx);

		if (wusb_dev_set_gtk(wusbhc, wusb_dev) < 0) {
			dev_err(&wusb_dev->usb_dev->dev,
				"%s: rekey device at port %d failed\n",
				__func__, wusb_dev->port_idx);
		}
		wusb_dev_put(wusb_dev);
	}

	/* Switch the host controller to use the new GTK. */
	mutex_lock(&wusbhc->mutex);
	wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid,
		&wusbhc->gtk.descr.bKeyData, key_size);
	mutex_unlock(&wusbhc->mutex);
}

/**
 * wusbhc_gtk_rekey - generate and distribute a new GTK
 * @wusbhc: the WUSB host controller
 *
 * Generate a new GTK and distribute it to all connected and
 * authenticated devices.  When all devices have the new GTK, the host
 * starts using it.
 *
 * This must be called after every device disconnect (see [WUSB]
 * section 6.2.11.2).
 */
void wusbhc_gtk_rekey(struct wusbhc *wusbhc)
{
	/*
	 * We need to submit a URB to the downstream WUSB devices in order to
	 * change the group key.  This can't be done while holding the
	 * wusbhc->mutex since that is also taken in the urb_enqueue routine
	 * and will cause a deadlock.  Instead, queue a work item to do
	 * it when the lock is not held
	 */
	queue_work(wusbhc->wq_security, &wusbhc->gtk_rekey_work);
}
OpenPOWER on IntegriCloud