1 /*
2  * Wireless USB Host Controller
3  * Security support: encryption enablement, etc
4  *
5  * Copyright (C) 2006 Intel Corporation
6  * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
7  *
8  * This program is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU General Public License version
10  * 2 as published by the Free Software Foundation.
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., 51 Franklin Street, Fifth Floor, Boston, MA
20  * 02110-1301, USA.
21  *
22  *
23  * FIXME: docs
24  */
25 #include <linux/types.h>
26 #include <linux/slab.h>
27 #include <linux/usb/ch9.h>
28 #include <linux/random.h>
29 #include "wusbhc.h"
30 
31 static void wusbhc_set_gtk_callback(struct urb *urb);
32 static void wusbhc_gtk_rekey_done_work(struct work_struct *work);
33 
wusbhc_sec_create(struct wusbhc * wusbhc)34 int wusbhc_sec_create(struct wusbhc *wusbhc)
35 {
36 	wusbhc->gtk.descr.bLength = sizeof(wusbhc->gtk.descr) + sizeof(wusbhc->gtk.data);
37 	wusbhc->gtk.descr.bDescriptorType = USB_DT_KEY;
38 	wusbhc->gtk.descr.bReserved = 0;
39 
40 	wusbhc->gtk_index = wusb_key_index(0, WUSB_KEY_INDEX_TYPE_GTK,
41 					   WUSB_KEY_INDEX_ORIGINATOR_HOST);
42 
43 	INIT_WORK(&wusbhc->gtk_rekey_done_work, wusbhc_gtk_rekey_done_work);
44 
45 	return 0;
46 }
47 
48 
49 /* Called when the HC is destroyed */
wusbhc_sec_destroy(struct wusbhc * wusbhc)50 void wusbhc_sec_destroy(struct wusbhc *wusbhc)
51 {
52 }
53 
54 
55 /**
56  * wusbhc_next_tkid - generate a new, currently unused, TKID
57  * @wusbhc:   the WUSB host controller
58  * @wusb_dev: the device whose PTK the TKID is for
59  *            (or NULL for a TKID for a GTK)
60  *
61  * The generated TKID consist of two parts: the device's authenicated
62  * address (or 0 or a GTK); and an incrementing number.  This ensures
63  * that TKIDs cannot be shared between devices and by the time the
64  * incrementing number wraps around the older TKIDs will no longer be
65  * in use (a maximum of two keys may be active at any one time).
66  */
wusbhc_next_tkid(struct wusbhc * wusbhc,struct wusb_dev * wusb_dev)67 static u32 wusbhc_next_tkid(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
68 {
69 	u32 *tkid;
70 	u32 addr;
71 
72 	if (wusb_dev == NULL) {
73 		tkid = &wusbhc->gtk_tkid;
74 		addr = 0;
75 	} else {
76 		tkid = &wusb_port_by_idx(wusbhc, wusb_dev->port_idx)->ptk_tkid;
77 		addr = wusb_dev->addr & 0x7f;
78 	}
79 
80 	*tkid = (addr << 8) | ((*tkid + 1) & 0xff);
81 
82 	return *tkid;
83 }
84 
wusbhc_generate_gtk(struct wusbhc * wusbhc)85 static void wusbhc_generate_gtk(struct wusbhc *wusbhc)
86 {
87 	const size_t key_size = sizeof(wusbhc->gtk.data);
88 	u32 tkid;
89 
90 	tkid = wusbhc_next_tkid(wusbhc, NULL);
91 
92 	wusbhc->gtk.descr.tTKID[0] = (tkid >>  0) & 0xff;
93 	wusbhc->gtk.descr.tTKID[1] = (tkid >>  8) & 0xff;
94 	wusbhc->gtk.descr.tTKID[2] = (tkid >> 16) & 0xff;
95 
96 	get_random_bytes(wusbhc->gtk.descr.bKeyData, key_size);
97 }
98 
99 /**
100  * wusbhc_sec_start - start the security management process
101  * @wusbhc: the WUSB host controller
102  *
103  * Generate and set an initial GTK on the host controller.
104  *
105  * Called when the HC is started.
106  */
wusbhc_sec_start(struct wusbhc * wusbhc)107 int wusbhc_sec_start(struct wusbhc *wusbhc)
108 {
109 	const size_t key_size = sizeof(wusbhc->gtk.data);
110 	int result;
111 
112 	wusbhc_generate_gtk(wusbhc);
113 
114 	result = wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid,
115 				 &wusbhc->gtk.descr.bKeyData, key_size);
116 	if (result < 0)
117 		dev_err(wusbhc->dev, "cannot set GTK for the host: %d\n",
118 			result);
119 
120 	return result;
121 }
122 
123 /**
124  * wusbhc_sec_stop - stop the security management process
125  * @wusbhc: the WUSB host controller
126  *
127  * Wait for any pending GTK rekeys to stop.
128  */
wusbhc_sec_stop(struct wusbhc * wusbhc)129 void wusbhc_sec_stop(struct wusbhc *wusbhc)
130 {
131 	cancel_work_sync(&wusbhc->gtk_rekey_done_work);
132 }
133 
134 
135 /** @returns encryption type name */
wusb_et_name(u8 x)136 const char *wusb_et_name(u8 x)
137 {
138 	switch (x) {
139 	case USB_ENC_TYPE_UNSECURE:	return "unsecure";
140 	case USB_ENC_TYPE_WIRED:	return "wired";
141 	case USB_ENC_TYPE_CCM_1:	return "CCM-1";
142 	case USB_ENC_TYPE_RSA_1:	return "RSA-1";
143 	default: 			return "unknown";
144 	}
145 }
146 EXPORT_SYMBOL_GPL(wusb_et_name);
147 
148 /*
149  * Set the device encryption method
150  *
151  * We tell the device which encryption method to use; we do this when
152  * setting up the device's security.
153  */
wusb_dev_set_encryption(struct usb_device * usb_dev,int value)154 static int wusb_dev_set_encryption(struct usb_device *usb_dev, int value)
155 {
156 	int result;
157 	struct device *dev = &usb_dev->dev;
158 	struct wusb_dev *wusb_dev = usb_dev->wusb_dev;
159 
160 	if (value) {
161 		value = wusb_dev->ccm1_etd.bEncryptionValue;
162 	} else {
163 		/* FIXME: should be wusb_dev->etd[UNSECURE].bEncryptionValue */
164 		value = 0;
165 	}
166 	/* Set device's */
167 	result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
168 			USB_REQ_SET_ENCRYPTION,
169 			USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
170 			value, 0, NULL, 0, 1000 /* FIXME: arbitrary */);
171 	if (result < 0)
172 		dev_err(dev, "Can't set device's WUSB encryption to "
173 			"%s (value %d): %d\n",
174 			wusb_et_name(wusb_dev->ccm1_etd.bEncryptionType),
175 			wusb_dev->ccm1_etd.bEncryptionValue,  result);
176 	return result;
177 }
178 
179 /*
180  * Set the GTK to be used by a device.
181  *
182  * The device must be authenticated.
183  */
wusb_dev_set_gtk(struct wusbhc * wusbhc,struct wusb_dev * wusb_dev)184 static int wusb_dev_set_gtk(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
185 {
186 	struct usb_device *usb_dev = wusb_dev->usb_dev;
187 
188 	return usb_control_msg(
189 		usb_dev, usb_sndctrlpipe(usb_dev, 0),
190 		USB_REQ_SET_DESCRIPTOR,
191 		USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
192 		USB_DT_KEY << 8 | wusbhc->gtk_index, 0,
193 		&wusbhc->gtk.descr, wusbhc->gtk.descr.bLength,
194 		1000);
195 }
196 
197 
198 /* FIXME: prototype for adding security */
wusb_dev_sec_add(struct wusbhc * wusbhc,struct usb_device * usb_dev,struct wusb_dev * wusb_dev)199 int wusb_dev_sec_add(struct wusbhc *wusbhc,
200 		     struct usb_device *usb_dev, struct wusb_dev *wusb_dev)
201 {
202 	int result, bytes, secd_size;
203 	struct device *dev = &usb_dev->dev;
204 	struct usb_security_descriptor *secd;
205 	const struct usb_encryption_descriptor *etd, *ccm1_etd = NULL;
206 	const void *itr, *top;
207 	char buf[64];
208 
209 	secd = kmalloc(sizeof(*secd), GFP_KERNEL);
210 	if (secd == NULL) {
211 		result = -ENOMEM;
212 		goto out;
213 	}
214 
215 	result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
216 				    0, secd, sizeof(*secd));
217 	if (result < sizeof(*secd)) {
218 		dev_err(dev, "Can't read security descriptor or "
219 			"not enough data: %d\n", result);
220 		goto out;
221 	}
222 	secd_size = le16_to_cpu(secd->wTotalLength);
223 	secd = krealloc(secd, secd_size, GFP_KERNEL);
224 	if (secd == NULL) {
225 		dev_err(dev, "Can't allocate space for security descriptors\n");
226 		goto out;
227 	}
228 	result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
229 				    0, secd, secd_size);
230 	if (result < secd_size) {
231 		dev_err(dev, "Can't read security descriptor or "
232 			"not enough data: %d\n", result);
233 		goto out;
234 	}
235 	bytes = 0;
236 	itr = &secd[1];
237 	top = (void *)secd + result;
238 	while (itr < top) {
239 		etd = itr;
240 		if (top - itr < sizeof(*etd)) {
241 			dev_err(dev, "BUG: bad device security descriptor; "
242 				"not enough data (%zu vs %zu bytes left)\n",
243 				top - itr, sizeof(*etd));
244 			break;
245 		}
246 		if (etd->bLength < sizeof(*etd)) {
247 			dev_err(dev, "BUG: bad device encryption descriptor; "
248 				"descriptor is too short "
249 				"(%u vs %zu needed)\n",
250 				etd->bLength, sizeof(*etd));
251 			break;
252 		}
253 		itr += etd->bLength;
254 		bytes += snprintf(buf + bytes, sizeof(buf) - bytes,
255 				  "%s (0x%02x/%02x) ",
256 				  wusb_et_name(etd->bEncryptionType),
257 				  etd->bEncryptionValue, etd->bAuthKeyIndex);
258 		if (etd->bEncryptionType == USB_ENC_TYPE_CCM_1)
259 			ccm1_etd = etd;
260 	}
261 	/* This code only supports CCM1 as of now. */
262 	/* FIXME: user has to choose which sec mode to use?
263 	 * In theory we want CCM */
264 	if (ccm1_etd == NULL) {
265 		dev_err(dev, "WUSB device doesn't support CCM1 encryption, "
266 			"can't use!\n");
267 		result = -EINVAL;
268 		goto out;
269 	}
270 	wusb_dev->ccm1_etd = *ccm1_etd;
271 	dev_dbg(dev, "supported encryption: %s; using %s (0x%02x/%02x)\n",
272 		buf, wusb_et_name(ccm1_etd->bEncryptionType),
273 		ccm1_etd->bEncryptionValue, ccm1_etd->bAuthKeyIndex);
274 	result = 0;
275 out:
276 	kfree(secd);
277 	return result;
278 }
279 
wusb_dev_sec_rm(struct wusb_dev * wusb_dev)280 void wusb_dev_sec_rm(struct wusb_dev *wusb_dev)
281 {
282 	/* Nothing so far */
283 }
284 
285 /**
286  * Update the address of an unauthenticated WUSB device
287  *
288  * Once we have successfully authenticated, we take it to addr0 state
289  * and then to a normal address.
290  *
291  * Before the device's address (as known by it) was usb_dev->devnum |
292  * 0x80 (unauthenticated address). With this we update it to usb_dev->devnum.
293  */
wusb_dev_update_address(struct wusbhc * wusbhc,struct wusb_dev * wusb_dev)294 int wusb_dev_update_address(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
295 {
296 	int result = -ENOMEM;
297 	struct usb_device *usb_dev = wusb_dev->usb_dev;
298 	struct device *dev = &usb_dev->dev;
299 	u8 new_address = wusb_dev->addr & 0x7F;
300 
301 	/* Set address 0 */
302 	result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
303 				 USB_REQ_SET_ADDRESS, 0,
304 				 0, 0, NULL, 0, 1000 /* FIXME: arbitrary */);
305 	if (result < 0) {
306 		dev_err(dev, "auth failed: can't set address 0: %d\n",
307 			result);
308 		goto error_addr0;
309 	}
310 	result = wusb_set_dev_addr(wusbhc, wusb_dev, 0);
311 	if (result < 0)
312 		goto error_addr0;
313 	usb_set_device_state(usb_dev, USB_STATE_DEFAULT);
314 	usb_ep0_reinit(usb_dev);
315 
316 	/* Set new (authenticated) address. */
317 	result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
318 				 USB_REQ_SET_ADDRESS, 0,
319 				 new_address, 0, NULL, 0,
320 				 1000 /* FIXME: arbitrary */);
321 	if (result < 0) {
322 		dev_err(dev, "auth failed: can't set address %u: %d\n",
323 			new_address, result);
324 		goto error_addr;
325 	}
326 	result = wusb_set_dev_addr(wusbhc, wusb_dev, new_address);
327 	if (result < 0)
328 		goto error_addr;
329 	usb_set_device_state(usb_dev, USB_STATE_ADDRESS);
330 	usb_ep0_reinit(usb_dev);
331 	usb_dev->authenticated = 1;
332 error_addr:
333 error_addr0:
334 	return result;
335 }
336 
337 /*
338  *
339  *
340  */
341 /* FIXME: split and cleanup */
wusb_dev_4way_handshake(struct wusbhc * wusbhc,struct wusb_dev * wusb_dev,struct wusb_ckhdid * ck)342 int wusb_dev_4way_handshake(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev,
343 			    struct wusb_ckhdid *ck)
344 {
345 	int result = -ENOMEM;
346 	struct usb_device *usb_dev = wusb_dev->usb_dev;
347 	struct device *dev = &usb_dev->dev;
348 	u32 tkid;
349 	__le32 tkid_le;
350 	struct usb_handshake *hs;
351 	struct aes_ccm_nonce ccm_n;
352 	u8 mic[8];
353 	struct wusb_keydvt_in keydvt_in;
354 	struct wusb_keydvt_out keydvt_out;
355 
356 	hs = kzalloc(3*sizeof(hs[0]), GFP_KERNEL);
357 	if (hs == NULL) {
358 		dev_err(dev, "can't allocate handshake data\n");
359 		goto error_kzalloc;
360 	}
361 
362 	/* We need to turn encryption before beginning the 4way
363 	 * hshake (WUSB1.0[.3.2.2]) */
364 	result = wusb_dev_set_encryption(usb_dev, 1);
365 	if (result < 0)
366 		goto error_dev_set_encryption;
367 
368 	tkid = wusbhc_next_tkid(wusbhc, wusb_dev);
369 	tkid_le = cpu_to_le32(tkid);
370 
371 	hs[0].bMessageNumber = 1;
372 	hs[0].bStatus = 0;
373 	memcpy(hs[0].tTKID, &tkid_le, sizeof(hs[0].tTKID));
374 	hs[0].bReserved = 0;
375 	memcpy(hs[0].CDID, &wusb_dev->cdid, sizeof(hs[0].CDID));
376 	get_random_bytes(&hs[0].nonce, sizeof(hs[0].nonce));
377 	memset(hs[0].MIC, 0, sizeof(hs[0].MIC));	/* Per WUSB1.0[T7-22] */
378 
379 	result = usb_control_msg(
380 		usb_dev, usb_sndctrlpipe(usb_dev, 0),
381 		USB_REQ_SET_HANDSHAKE,
382 		USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
383 		1, 0, &hs[0], sizeof(hs[0]), 1000 /* FIXME: arbitrary */);
384 	if (result < 0) {
385 		dev_err(dev, "Handshake1: request failed: %d\n", result);
386 		goto error_hs1;
387 	}
388 
389 	/* Handshake 2, from the device -- need to verify fields */
390 	result = usb_control_msg(
391 		usb_dev, usb_rcvctrlpipe(usb_dev, 0),
392 		USB_REQ_GET_HANDSHAKE,
393 		USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
394 		2, 0, &hs[1], sizeof(hs[1]), 1000 /* FIXME: arbitrary */);
395 	if (result < 0) {
396 		dev_err(dev, "Handshake2: request failed: %d\n", result);
397 		goto error_hs2;
398 	}
399 
400 	result = -EINVAL;
401 	if (hs[1].bMessageNumber != 2) {
402 		dev_err(dev, "Handshake2 failed: bad message number %u\n",
403 			hs[1].bMessageNumber);
404 		goto error_hs2;
405 	}
406 	if (hs[1].bStatus != 0) {
407 		dev_err(dev, "Handshake2 failed: bad status %u\n",
408 			hs[1].bStatus);
409 		goto error_hs2;
410 	}
411 	if (memcmp(hs[0].tTKID, hs[1].tTKID, sizeof(hs[0].tTKID))) {
412 		dev_err(dev, "Handshake2 failed: TKID mismatch "
413 			"(#1 0x%02x%02x%02x vs #2 0x%02x%02x%02x)\n",
414 			hs[0].tTKID[0], hs[0].tTKID[1], hs[0].tTKID[2],
415 			hs[1].tTKID[0], hs[1].tTKID[1], hs[1].tTKID[2]);
416 		goto error_hs2;
417 	}
418 	if (memcmp(hs[0].CDID, hs[1].CDID, sizeof(hs[0].CDID))) {
419 		dev_err(dev, "Handshake2 failed: CDID mismatch\n");
420 		goto error_hs2;
421 	}
422 
423 	/* Setup the CCM nonce */
424 	memset(&ccm_n.sfn, 0, sizeof(ccm_n.sfn));	/* Per WUSB1.0[6.5.2] */
425 	memcpy(ccm_n.tkid, &tkid_le, sizeof(ccm_n.tkid));
426 	ccm_n.src_addr = wusbhc->uwb_rc->uwb_dev.dev_addr;
427 	ccm_n.dest_addr.data[0] = wusb_dev->addr;
428 	ccm_n.dest_addr.data[1] = 0;
429 
430 	/* Derive the KCK and PTK from CK, the CCM, H and D nonces */
431 	memcpy(keydvt_in.hnonce, hs[0].nonce, sizeof(keydvt_in.hnonce));
432 	memcpy(keydvt_in.dnonce, hs[1].nonce, sizeof(keydvt_in.dnonce));
433 	result = wusb_key_derive(&keydvt_out, ck->data, &ccm_n, &keydvt_in);
434 	if (result < 0) {
435 		dev_err(dev, "Handshake2 failed: cannot derive keys: %d\n",
436 			result);
437 		goto error_hs2;
438 	}
439 
440 	/* Compute MIC and verify it */
441 	result = wusb_oob_mic(mic, keydvt_out.kck, &ccm_n, &hs[1]);
442 	if (result < 0) {
443 		dev_err(dev, "Handshake2 failed: cannot compute MIC: %d\n",
444 			result);
445 		goto error_hs2;
446 	}
447 
448 	if (memcmp(hs[1].MIC, mic, sizeof(hs[1].MIC))) {
449 		dev_err(dev, "Handshake2 failed: MIC mismatch\n");
450 		goto error_hs2;
451 	}
452 
453 	/* Send Handshake3 */
454 	hs[2].bMessageNumber = 3;
455 	hs[2].bStatus = 0;
456 	memcpy(hs[2].tTKID, &tkid_le, sizeof(hs[2].tTKID));
457 	hs[2].bReserved = 0;
458 	memcpy(hs[2].CDID, &wusb_dev->cdid, sizeof(hs[2].CDID));
459 	memcpy(hs[2].nonce, hs[0].nonce, sizeof(hs[2].nonce));
460 	result = wusb_oob_mic(hs[2].MIC, keydvt_out.kck, &ccm_n, &hs[2]);
461 	if (result < 0) {
462 		dev_err(dev, "Handshake3 failed: cannot compute MIC: %d\n",
463 			result);
464 		goto error_hs2;
465 	}
466 
467 	result = usb_control_msg(
468 		usb_dev, usb_sndctrlpipe(usb_dev, 0),
469 		USB_REQ_SET_HANDSHAKE,
470 		USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
471 		3, 0, &hs[2], sizeof(hs[2]), 1000 /* FIXME: arbitrary */);
472 	if (result < 0) {
473 		dev_err(dev, "Handshake3: request failed: %d\n", result);
474 		goto error_hs3;
475 	}
476 
477 	result = wusbhc->set_ptk(wusbhc, wusb_dev->port_idx, tkid,
478 				 keydvt_out.ptk, sizeof(keydvt_out.ptk));
479 	if (result < 0)
480 		goto error_wusbhc_set_ptk;
481 
482 	result = wusb_dev_set_gtk(wusbhc, wusb_dev);
483 	if (result < 0) {
484 		dev_err(dev, "Set GTK for device: request failed: %d\n",
485 			result);
486 		goto error_wusbhc_set_gtk;
487 	}
488 
489 	/* Update the device's address from unauth to auth */
490 	if (usb_dev->authenticated == 0) {
491 		result = wusb_dev_update_address(wusbhc, wusb_dev);
492 		if (result < 0)
493 			goto error_dev_update_address;
494 	}
495 	result = 0;
496 	dev_info(dev, "device authenticated\n");
497 
498 error_dev_update_address:
499 error_wusbhc_set_gtk:
500 error_wusbhc_set_ptk:
501 error_hs3:
502 error_hs2:
503 error_hs1:
504 	memset(hs, 0, 3*sizeof(hs[0]));
505 	memset(&keydvt_out, 0, sizeof(keydvt_out));
506 	memset(&keydvt_in, 0, sizeof(keydvt_in));
507 	memset(&ccm_n, 0, sizeof(ccm_n));
508 	memset(mic, 0, sizeof(mic));
509 	if (result < 0)
510 		wusb_dev_set_encryption(usb_dev, 0);
511 error_dev_set_encryption:
512 	kfree(hs);
513 error_kzalloc:
514 	return result;
515 }
516 
517 /*
518  * Once all connected and authenticated devices have received the new
519  * GTK, switch the host to using it.
520  */
wusbhc_gtk_rekey_done_work(struct work_struct * work)521 static void wusbhc_gtk_rekey_done_work(struct work_struct *work)
522 {
523 	struct wusbhc *wusbhc = container_of(work, struct wusbhc, gtk_rekey_done_work);
524 	size_t key_size = sizeof(wusbhc->gtk.data);
525 
526 	mutex_lock(&wusbhc->mutex);
527 
528 	if (--wusbhc->pending_set_gtks == 0)
529 		wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid, &wusbhc->gtk.descr.bKeyData, key_size);
530 
531 	mutex_unlock(&wusbhc->mutex);
532 }
533 
wusbhc_set_gtk_callback(struct urb * urb)534 static void wusbhc_set_gtk_callback(struct urb *urb)
535 {
536 	struct wusbhc *wusbhc = urb->context;
537 
538 	queue_work(wusbd, &wusbhc->gtk_rekey_done_work);
539 }
540 
541 /**
542  * wusbhc_gtk_rekey - generate and distribute a new GTK
543  * @wusbhc: the WUSB host controller
544  *
545  * Generate a new GTK and distribute it to all connected and
546  * authenticated devices.  When all devices have the new GTK, the host
547  * starts using it.
548  *
549  * This must be called after every device disconnect (see [WUSB]
550  * section 6.2.11.2).
551  */
wusbhc_gtk_rekey(struct wusbhc * wusbhc)552 void wusbhc_gtk_rekey(struct wusbhc *wusbhc)
553 {
554 	static const size_t key_size = sizeof(wusbhc->gtk.data);
555 	int p;
556 
557 	wusbhc_generate_gtk(wusbhc);
558 
559 	for (p = 0; p < wusbhc->ports_max; p++) {
560 		struct wusb_dev *wusb_dev;
561 
562 		wusb_dev = wusbhc->port[p].wusb_dev;
563 		if (!wusb_dev || !wusb_dev->usb_dev || !wusb_dev->usb_dev->authenticated)
564 			continue;
565 
566 		usb_fill_control_urb(wusb_dev->set_gtk_urb, wusb_dev->usb_dev,
567 				     usb_sndctrlpipe(wusb_dev->usb_dev, 0),
568 				     (void *)wusb_dev->set_gtk_req,
569 				     &wusbhc->gtk.descr, wusbhc->gtk.descr.bLength,
570 				     wusbhc_set_gtk_callback, wusbhc);
571 		if (usb_submit_urb(wusb_dev->set_gtk_urb, GFP_KERNEL) == 0)
572 			wusbhc->pending_set_gtks++;
573 	}
574 	if (wusbhc->pending_set_gtks == 0)
575 		wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid, &wusbhc->gtk.descr.bKeyData, key_size);
576 }
577