drivers/usb/wusbcore/security.c

   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 <linux/export.h>
  30 #include "wusbhc.h"
  31
  32 static void wusbhc_gtk_rekey_work(struct work_struct *work);
  33
  34 int wusbhc_sec_create(struct wusbhc *wusbhc)
  35 {
  36         wusbhc->gtk.descr.bLength = sizeof(wusbhc->gtk.descr) +
  37                 sizeof(wusbhc->gtk.data);
  38         wusbhc->gtk.descr.bDescriptorType = USB_DT_KEY;
  39         wusbhc->gtk.descr.bReserved = 0;
  40         wusbhc->gtk_index = 0;
  41
  42         INIT_WORK(&wusbhc->gtk_rekey_work, wusbhc_gtk_rekey_work);
  43
  44         return 0;
  45 }
  46
  47
  48 /* Called when the HC is destroyed */
  49 void wusbhc_sec_destroy(struct wusbhc *wusbhc)
  50 {
  51 }
  52
  53
  54 /**
  55  * wusbhc_next_tkid - generate a new, currently unused, TKID
  56  * @wusbhc:   the WUSB host controller
  57  * @wusb_dev: the device whose PTK the TKID is for
  58  *            (or NULL for a TKID for a GTK)
  59  *
  60  * The generated TKID consists of two parts: the device's authenticated
  61  * address (or 0 or a GTK); and an incrementing number.  This ensures
  62  * that TKIDs cannot be shared between devices and by the time the
  63  * incrementing number wraps around the older TKIDs will no longer be
  64  * in use (a maximum of two keys may be active at any one time).
  65  */
  66 static u32 wusbhc_next_tkid(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
  67 {
  68         u32 *tkid;
  69         u32 addr;
  70
  71         if (wusb_dev == NULL) {
  72                 tkid = &wusbhc->gtk_tkid;
  73                 addr = 0;
  74         } else {
  75                 tkid = &wusb_port_by_idx(wusbhc, wusb_dev->port_idx)->ptk_tkid;
  76                 addr = wusb_dev->addr & 0x7f;
  77         }
  78
  79         *tkid = (addr << 8) | ((*tkid + 1) & 0xff);
  80
  81         return *tkid;
  82 }
  83
  84 static void wusbhc_generate_gtk(struct wusbhc *wusbhc)
  85 {
  86         const size_t key_size = sizeof(wusbhc->gtk.data);
  87         u32 tkid;
  88
  89         tkid = wusbhc_next_tkid(wusbhc, NULL);
  90
  91         wusbhc->gtk.descr.tTKID[0] = (tkid >>  0) & 0xff;
  92         wusbhc->gtk.descr.tTKID[1] = (tkid >>  8) & 0xff;
  93         wusbhc->gtk.descr.tTKID[2] = (tkid >> 16) & 0xff;
  94
  95         get_random_bytes(wusbhc->gtk.descr.bKeyData, key_size);
  96 }
  97
  98 /**
  99  * wusbhc_sec_start - start the security management process
 100  * @wusbhc: the WUSB host controller
 101  *
 102  * Generate and set an initial GTK on the host controller.
 103  *
 104  * Called when the HC is started.
 105  */
 106 int wusbhc_sec_start(struct wusbhc *wusbhc)
 107 {
 108         const size_t key_size = sizeof(wusbhc->gtk.data);
 109         int result;
 110
 111         wusbhc_generate_gtk(wusbhc);
 112
 113         result = wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid,
 114                                 &wusbhc->gtk.descr.bKeyData, key_size);
 115         if (result < 0)
 116                 dev_err(wusbhc->dev, "cannot set GTK for the host: %d\n",
 117                         result);
 118
 119         return result;
 120 }
 121
 122 /**
 123  * wusbhc_sec_stop - stop the security management process
 124  * @wusbhc: the WUSB host controller
 125  *
 126  * Wait for any pending GTK rekeys to stop.
 127  */
 128 void wusbhc_sec_stop(struct wusbhc *wusbhc)
 129 {
 130         cancel_work_sync(&wusbhc->gtk_rekey_work);
 131 }
 132
 133
 134 /** @returns encryption type name */
 135 const char *wusb_et_name(u8 x)
 136 {
 137         switch (x) {
 138         case USB_ENC_TYPE_UNSECURE:     return "unsecure";
 139         case USB_ENC_TYPE_WIRED:        return "wired";
 140         case USB_ENC_TYPE_CCM_1:        return "CCM-1";
 141         case USB_ENC_TYPE_RSA_1:        return "RSA-1";
 142         default:                        return "unknown";
 143         }
 144 }
 145 EXPORT_SYMBOL_GPL(wusb_et_name);
 146
 147 /*
 148  * Set the device encryption method
 149  *
 150  * We tell the device which encryption method to use; we do this when
 151  * setting up the device's security.
 152  */
 153 static int wusb_dev_set_encryption(struct usb_device *usb_dev, int value)
 154 {
 155         int result;
 156         struct device *dev = &usb_dev->dev;
 157         struct wusb_dev *wusb_dev = usb_dev->wusb_dev;
 158
 159         if (value) {
 160                 value = wusb_dev->ccm1_etd.bEncryptionValue;
 161         } else {
 162                 /* FIXME: should be wusb_dev->etd[UNSECURE].bEncryptionValue */
 163                 value = 0;
 164         }
 165         /* Set device's */
 166         result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
 167                         USB_REQ_SET_ENCRYPTION,
 168                         USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 169                         value, 0, NULL, 0, USB_CTRL_SET_TIMEOUT);
 170         if (result < 0)
 171                 dev_err(dev, "Can't set device's WUSB encryption to "
 172                         "%s (value %d): %d\n",
 173                         wusb_et_name(wusb_dev->ccm1_etd.bEncryptionType),
 174                         wusb_dev->ccm1_etd.bEncryptionValue,  result);
 175         return result;
 176 }
 177
 178 /*
 179  * Set the GTK to be used by a device.
 180  *
 181  * The device must be authenticated.
 182  */
 183 static int wusb_dev_set_gtk(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
 184 {
 185         struct usb_device *usb_dev = wusb_dev->usb_dev;
 186         u8 key_index = wusb_key_index(wusbhc->gtk_index,
 187                 WUSB_KEY_INDEX_TYPE_GTK, WUSB_KEY_INDEX_ORIGINATOR_HOST);
 188
 189         return usb_control_msg(
 190                 usb_dev, usb_sndctrlpipe(usb_dev, 0),
 191                 USB_REQ_SET_DESCRIPTOR,
 192                 USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 193                 USB_DT_KEY << 8 | key_index, 0,
 194                 &wusbhc->gtk.descr, wusbhc->gtk.descr.bLength,
 195                 USB_CTRL_SET_TIMEOUT);
 196 }
 197
 198
 199 /* FIXME: prototype for adding security */
 200 int wusb_dev_sec_add(struct wusbhc *wusbhc,
 201                      struct usb_device *usb_dev, struct wusb_dev *wusb_dev)
 202 {
 203         int result, bytes, secd_size;
 204         struct device *dev = &usb_dev->dev;
 205         struct usb_security_descriptor *secd, *new_secd;
 206         const struct usb_encryption_descriptor *etd, *ccm1_etd = NULL;
 207         const void *itr, *top;
 208         char buf[64];
 209
 210         secd = kmalloc(sizeof(*secd), GFP_KERNEL);
 211         if (secd == NULL) {
 212                 result = -ENOMEM;
 213                 goto out;
 214         }
 215
 216         result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
 217                                     0, secd, sizeof(*secd));
 218         if (result < sizeof(*secd)) {
 219                 dev_err(dev, "Can't read security descriptor or "
 220                         "not enough data: %d\n", result);
 221                 goto out;
 222         }
 223         secd_size = le16_to_cpu(secd->wTotalLength);
 224         new_secd = krealloc(secd, secd_size, GFP_KERNEL);
 225         if (new_secd == NULL) {
 226                 dev_err(dev,
 227                         "Can't allocate space for security descriptors\n");
 228                 goto out;
 229         }
 230         secd = new_secd;
 231         result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
 232                                     0, secd, secd_size);
 233         if (result < secd_size) {
 234                 dev_err(dev, "Can't read security descriptor or "
 235                         "not enough data: %d\n", result);
 236                 goto out;
 237         }
 238         bytes = 0;
 239         itr = &secd[1];
 240         top = (void *)secd + result;
 241         while (itr < top) {
 242                 etd = itr;
 243                 if (top - itr < sizeof(*etd)) {
 244                         dev_err(dev, "BUG: bad device security descriptor; "
 245                                 "not enough data (%zu vs %zu bytes left)\n",
 246                                 top - itr, sizeof(*etd));
 247                         break;
 248                 }
 249                 if (etd->bLength < sizeof(*etd)) {
 250                         dev_err(dev, "BUG: bad device encryption descriptor; "
 251                                 "descriptor is too short "
 252                                 "(%u vs %zu needed)\n",
 253                                 etd->bLength, sizeof(*etd));
 254                         break;
 255                 }
 256                 itr += etd->bLength;
 257                 bytes += snprintf(buf + bytes, sizeof(buf) - bytes,
 258                                   "%s (0x%02x/%02x) ",
 259                                   wusb_et_name(etd->bEncryptionType),
 260                                   etd->bEncryptionValue, etd->bAuthKeyIndex);
 261                 if (etd->bEncryptionType == USB_ENC_TYPE_CCM_1)
 262                         ccm1_etd = etd;
 263         }
 264         /* This code only supports CCM1 as of now. */
 265         /* FIXME: user has to choose which sec mode to use?
 266          * In theory we want CCM */
 267         if (ccm1_etd == NULL) {
 268                 dev_err(dev, "WUSB device doesn't support CCM1 encryption, "
 269                         "can't use!\n");
 270                 result = -EINVAL;
 271                 goto out;
 272         }
 273         wusb_dev->ccm1_etd = *ccm1_etd;
 274         dev_dbg(dev, "supported encryption: %s; using %s (0x%02x/%02x)\n",
 275                 buf, wusb_et_name(ccm1_etd->bEncryptionType),
 276                 ccm1_etd->bEncryptionValue, ccm1_etd->bAuthKeyIndex);
 277         result = 0;
 278 out:
 279         kfree(secd);
 280         return result;
 281 }
 282
 283 void wusb_dev_sec_rm(struct wusb_dev *wusb_dev)
 284 {
 285         /* Nothing so far */
 286 }
 287
 288 /**
 289  * Update the address of an unauthenticated WUSB device
 290  *
 291  * Once we have successfully authenticated, we take it to addr0 state
 292  * and then to a normal address.
 293  *
 294  * Before the device's address (as known by it) was usb_dev->devnum |
 295  * 0x80 (unauthenticated address). With this we update it to usb_dev->devnum.
 296  */
 297 int wusb_dev_update_address(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
 298 {
 299         int result = -ENOMEM;
 300         struct usb_device *usb_dev = wusb_dev->usb_dev;
 301         struct device *dev = &usb_dev->dev;
 302         u8 new_address = wusb_dev->addr & 0x7F;
 303
 304         /* Set address 0 */
 305         result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
 306                         USB_REQ_SET_ADDRESS,
 307                         USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 308                          0, 0, NULL, 0, USB_CTRL_SET_TIMEOUT);
 309         if (result < 0) {
 310                 dev_err(dev, "auth failed: can't set address 0: %d\n",
 311                         result);
 312                 goto error_addr0;
 313         }
 314         result = wusb_set_dev_addr(wusbhc, wusb_dev, 0);
 315         if (result < 0)
 316                 goto error_addr0;
 317         usb_set_device_state(usb_dev, USB_STATE_DEFAULT);
 318         usb_ep0_reinit(usb_dev);
 319
 320         /* Set new (authenticated) address. */
 321         result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
 322                         USB_REQ_SET_ADDRESS,
 323                         USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 324                         new_address, 0, NULL, 0,
 325                         USB_CTRL_SET_TIMEOUT);
 326         if (result < 0) {
 327                 dev_err(dev, "auth failed: can't set address %u: %d\n",
 328                         new_address, result);
 329                 goto error_addr;
 330         }
 331         result = wusb_set_dev_addr(wusbhc, wusb_dev, new_address);
 332         if (result < 0)
 333                 goto error_addr;
 334         usb_set_device_state(usb_dev, USB_STATE_ADDRESS);
 335         usb_ep0_reinit(usb_dev);
 336         usb_dev->authenticated = 1;
 337 error_addr:
 338 error_addr0:
 339         return result;
 340 }
 341
 342 /*
 343  *
 344  *
 345  */
 346 /* FIXME: split and cleanup */
 347 int wusb_dev_4way_handshake(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev,
 348                             struct wusb_ckhdid *ck)
 349 {
 350         int result = -ENOMEM;
 351         struct usb_device *usb_dev = wusb_dev->usb_dev;
 352         struct device *dev = &usb_dev->dev;
 353         u32 tkid;
 354         __le32 tkid_le;
 355         struct usb_handshake *hs;
 356         struct aes_ccm_nonce ccm_n;
 357         u8 mic[8];
 358         struct wusb_keydvt_in keydvt_in;
 359         struct wusb_keydvt_out keydvt_out;
 360
 361         hs = kcalloc(3, sizeof(hs[0]), GFP_KERNEL);
 362         if (hs == NULL) {
 363                 dev_err(dev, "can't allocate handshake data\n");
 364                 goto error_kzalloc;
 365         }
 366
 367         /* We need to turn encryption before beginning the 4way
 368          * hshake (WUSB1.0[.3.2.2]) */
 369         result = wusb_dev_set_encryption(usb_dev, 1);
 370         if (result < 0)
 371                 goto error_dev_set_encryption;
 372
 373         tkid = wusbhc_next_tkid(wusbhc, wusb_dev);
 374         tkid_le = cpu_to_le32(tkid);
 375
 376         hs[0].bMessageNumber = 1;
 377         hs[0].bStatus = 0;
 378         memcpy(hs[0].tTKID, &tkid_le, sizeof(hs[0].tTKID));
 379         hs[0].bReserved = 0;
 380         memcpy(hs[0].CDID, &wusb_dev->cdid, sizeof(hs[0].CDID));
 381         get_random_bytes(&hs[0].nonce, sizeof(hs[0].nonce));
 382         memset(hs[0].MIC, 0, sizeof(hs[0].MIC)); /* Per WUSB1.0[T7-22] */
 383
 384         result = usb_control_msg(
 385                 usb_dev, usb_sndctrlpipe(usb_dev, 0),
 386                 USB_REQ_SET_HANDSHAKE,
 387                 USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 388                 1, 0, &hs[0], sizeof(hs[0]), USB_CTRL_SET_TIMEOUT);
 389         if (result < 0) {
 390                 dev_err(dev, "Handshake1: request failed: %d\n", result);
 391                 goto error_hs1;
 392         }
 393
 394         /* Handshake 2, from the device -- need to verify fields */
 395         result = usb_control_msg(
 396                 usb_dev, usb_rcvctrlpipe(usb_dev, 0),
 397                 USB_REQ_GET_HANDSHAKE,
 398                 USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 399                 2, 0, &hs[1], sizeof(hs[1]), USB_CTRL_GET_TIMEOUT);
 400         if (result < 0) {
 401                 dev_err(dev, "Handshake2: request failed: %d\n", result);
 402                 goto error_hs2;
 403         }
 404
 405         result = -EINVAL;
 406         if (hs[1].bMessageNumber != 2) {
 407                 dev_err(dev, "Handshake2 failed: bad message number %u\n",
 408                         hs[1].bMessageNumber);
 409                 goto error_hs2;
 410         }
 411         if (hs[1].bStatus != 0) {
 412                 dev_err(dev, "Handshake2 failed: bad status %u\n",
 413                         hs[1].bStatus);
 414                 goto error_hs2;
 415         }
 416         if (memcmp(hs[0].tTKID, hs[1].tTKID, sizeof(hs[0].tTKID))) {
 417                 dev_err(dev, "Handshake2 failed: TKID mismatch "
 418                         "(#1 0x%02x%02x%02x vs #2 0x%02x%02x%02x)\n",
 419                         hs[0].tTKID[0], hs[0].tTKID[1], hs[0].tTKID[2],
 420                         hs[1].tTKID[0], hs[1].tTKID[1], hs[1].tTKID[2]);
 421                 goto error_hs2;
 422         }
 423         if (memcmp(hs[0].CDID, hs[1].CDID, sizeof(hs[0].CDID))) {
 424                 dev_err(dev, "Handshake2 failed: CDID mismatch\n");
 425                 goto error_hs2;
 426         }
 427
 428         /* Setup the CCM nonce */
 429         memset(&ccm_n.sfn, 0, sizeof(ccm_n.sfn)); /* Per WUSB1.0[6.5.2] */
 430         memcpy(ccm_n.tkid, &tkid_le, sizeof(ccm_n.tkid));
 431         ccm_n.src_addr = wusbhc->uwb_rc->uwb_dev.dev_addr;
 432         ccm_n.dest_addr.data[0] = wusb_dev->addr;
 433         ccm_n.dest_addr.data[1] = 0;
 434
 435         /* Derive the KCK and PTK from CK, the CCM, H and D nonces */
 436         memcpy(keydvt_in.hnonce, hs[0].nonce, sizeof(keydvt_in.hnonce));
 437         memcpy(keydvt_in.dnonce, hs[1].nonce, sizeof(keydvt_in.dnonce));
 438         result = wusb_key_derive(&keydvt_out, ck->data, &ccm_n, &keydvt_in);
 439         if (result < 0) {
 440                 dev_err(dev, "Handshake2 failed: cannot derive keys: %d\n",
 441                         result);
 442                 goto error_hs2;
 443         }
 444
 445         /* Compute MIC and verify it */
 446         result = wusb_oob_mic(mic, keydvt_out.kck, &ccm_n, &hs[1]);
 447         if (result < 0) {
 448                 dev_err(dev, "Handshake2 failed: cannot compute MIC: %d\n",
 449                         result);
 450                 goto error_hs2;
 451         }
 452
 453         if (memcmp(hs[1].MIC, mic, sizeof(hs[1].MIC))) {
 454                 dev_err(dev, "Handshake2 failed: MIC mismatch\n");
 455                 goto error_hs2;
 456         }
 457
 458         /* Send Handshake3 */
 459         hs[2].bMessageNumber = 3;
 460         hs[2].bStatus = 0;
 461         memcpy(hs[2].tTKID, &tkid_le, sizeof(hs[2].tTKID));
 462         hs[2].bReserved = 0;
 463         memcpy(hs[2].CDID, &wusb_dev->cdid, sizeof(hs[2].CDID));
 464         memcpy(hs[2].nonce, hs[0].nonce, sizeof(hs[2].nonce));
 465         result = wusb_oob_mic(hs[2].MIC, keydvt_out.kck, &ccm_n, &hs[2]);
 466         if (result < 0) {
 467                 dev_err(dev, "Handshake3 failed: cannot compute MIC: %d\n",
 468                         result);
 469                 goto error_hs2;
 470         }
 471
 472         result = usb_control_msg(
 473                 usb_dev, usb_sndctrlpipe(usb_dev, 0),
 474                 USB_REQ_SET_HANDSHAKE,
 475                 USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 476                 3, 0, &hs[2], sizeof(hs[2]), USB_CTRL_SET_TIMEOUT);
 477         if (result < 0) {
 478                 dev_err(dev, "Handshake3: request failed: %d\n", result);
 479                 goto error_hs3;
 480         }
 481
 482         result = wusbhc->set_ptk(wusbhc, wusb_dev->port_idx, tkid,
 483                                  keydvt_out.ptk, sizeof(keydvt_out.ptk));
 484         if (result < 0)
 485                 goto error_wusbhc_set_ptk;
 486
 487         result = wusb_dev_set_gtk(wusbhc, wusb_dev);
 488         if (result < 0) {
 489                 dev_err(dev, "Set GTK for device: request failed: %d\n",
 490                         result);
 491                 goto error_wusbhc_set_gtk;
 492         }
 493
 494         /* Update the device's address from unauth to auth */
 495         if (usb_dev->authenticated == 0) {
 496                 result = wusb_dev_update_address(wusbhc, wusb_dev);
 497                 if (result < 0)
 498                         goto error_dev_update_address;
 499         }
 500         result = 0;
 501         dev_info(dev, "device authenticated\n");
 502
 503 error_dev_update_address:
 504 error_wusbhc_set_gtk:
 505 error_wusbhc_set_ptk:
 506 error_hs3:
 507 error_hs2:
 508 error_hs1:
 509         memset(hs, 0, 3*sizeof(hs[0]));
 510         memset(&keydvt_out, 0, sizeof(keydvt_out));
 511         memset(&keydvt_in, 0, sizeof(keydvt_in));
 512         memset(&ccm_n, 0, sizeof(ccm_n));
 513         memset(mic, 0, sizeof(mic));
 514         if (result < 0)
 515                 wusb_dev_set_encryption(usb_dev, 0);
 516 error_dev_set_encryption:
 517         kfree(hs);
 518 error_kzalloc:
 519         return result;
 520 }
 521
 522 /*
 523  * Once all connected and authenticated devices have received the new
 524  * GTK, switch the host to using it.
 525  */
 526 static void wusbhc_gtk_rekey_work(struct work_struct *work)
 527 {
 528         struct wusbhc *wusbhc = container_of(work,
 529                                         struct wusbhc, gtk_rekey_work);
 530         size_t key_size = sizeof(wusbhc->gtk.data);
 531         int port_idx;
 532         struct wusb_dev *wusb_dev, *wusb_dev_next;
 533         LIST_HEAD(rekey_list);
 534
 535         mutex_lock(&wusbhc->mutex);
 536         /* generate the new key */
 537         wusbhc_generate_gtk(wusbhc);
 538         /* roll the gtk index. */
 539         wusbhc->gtk_index = (wusbhc->gtk_index + 1) % (WUSB_KEY_INDEX_MAX + 1);
 540         /*
 541          * Save all connected devices on a list while holding wusbhc->mutex and
 542          * take a reference to each one.  Then submit the set key request to
 543          * them after releasing the lock in order to avoid a deadlock.
 544          */
 545         for (port_idx = 0; port_idx < wusbhc->ports_max; port_idx++) {
 546                 wusb_dev = wusbhc->port[port_idx].wusb_dev;
 547                 if (!wusb_dev || !wusb_dev->usb_dev
 548                         || !wusb_dev->usb_dev->authenticated)
 549                         continue;
 550
 551                 wusb_dev_get(wusb_dev);
 552                 list_add_tail(&wusb_dev->rekey_node, &rekey_list);
 553         }
 554         mutex_unlock(&wusbhc->mutex);
 555
 556         /* Submit the rekey requests without holding wusbhc->mutex. */
 557         list_for_each_entry_safe(wusb_dev, wusb_dev_next, &rekey_list,
 558                 rekey_node) {
 559                 list_del_init(&wusb_dev->rekey_node);
 560                 dev_dbg(&wusb_dev->usb_dev->dev,
 561                         "%s: rekey device at port %d\n",
 562                         __func__, wusb_dev->port_idx);
 563
 564                 if (wusb_dev_set_gtk(wusbhc, wusb_dev) < 0) {
 565                         dev_err(&wusb_dev->usb_dev->dev,
 566                                 "%s: rekey device at port %d failed\n",
 567                                 __func__, wusb_dev->port_idx);
 568                 }
 569                 wusb_dev_put(wusb_dev);
 570         }
 571
 572         /* Switch the host controller to use the new GTK. */
 573         mutex_lock(&wusbhc->mutex);
 574         wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid,
 575                 &wusbhc->gtk.descr.bKeyData, key_size);
 576         mutex_unlock(&wusbhc->mutex);
 577 }
 578
 579 /**
 580  * wusbhc_gtk_rekey - generate and distribute a new GTK
 581  * @wusbhc: the WUSB host controller
 582  *
 583  * Generate a new GTK and distribute it to all connected and
 584  * authenticated devices.  When all devices have the new GTK, the host
 585  * starts using it.
 586  *
 587  * This must be called after every device disconnect (see [WUSB]
 588  * section 6.2.11.2).
 589  */
 590 void wusbhc_gtk_rekey(struct wusbhc *wusbhc)
 591 {
 592         /*
 593          * We need to submit a URB to the downstream WUSB devices in order to
 594          * change the group key.  This can't be done while holding the
 595          * wusbhc->mutex since that is also taken in the urb_enqueue routine
 596          * and will cause a deadlock.  Instead, queue a work item to do
 597          * it when the lock is not held
 598          */
 599         queue_work(wusbd, &wusbhc->gtk_rekey_work);
 600 }