kernel/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         /*
  37          * WQ is singlethread because we need to serialize rekey operations.
  38          * Use a separate workqueue for security operations instead of the
  39          * wusbd workqueue because security operations may need to communicate
  40          * directly with downstream wireless devices using synchronous URBs.
  41          * If a device is not responding, this could block other host
  42          * controller operations.
  43          */
  44         wusbhc->wq_security = create_singlethread_workqueue("wusbd_security");
  45         if (wusbhc->wq_security == NULL) {
  46                 pr_err("WUSB-core: Cannot create wusbd_security workqueue\n");
  47                 return -ENOMEM;
  48         }
  49
  50         wusbhc->gtk.descr.bLength = sizeof(wusbhc->gtk.descr) +
  51                 sizeof(wusbhc->gtk.data);
  52         wusbhc->gtk.descr.bDescriptorType = USB_DT_KEY;
  53         wusbhc->gtk.descr.bReserved = 0;
  54         wusbhc->gtk_index = 0;
  55
  56         INIT_WORK(&wusbhc->gtk_rekey_work, wusbhc_gtk_rekey_work);
  57
  58         return 0;
  59 }
  60
  61
  62 /* Called when the HC is destroyed */
  63 void wusbhc_sec_destroy(struct wusbhc *wusbhc)
  64 {
  65         destroy_workqueue(wusbhc->wq_security);
  66 }
  67
  68
  69 /**
  70  * wusbhc_next_tkid - generate a new, currently unused, TKID
  71  * @wusbhc:   the WUSB host controller
  72  * @wusb_dev: the device whose PTK the TKID is for
  73  *            (or NULL for a TKID for a GTK)
  74  *
  75  * The generated TKID consists of two parts: the device's authenticated
  76  * address (or 0 or a GTK); and an incrementing number.  This ensures
  77  * that TKIDs cannot be shared between devices and by the time the
  78  * incrementing number wraps around the older TKIDs will no longer be
  79  * in use (a maximum of two keys may be active at any one time).
  80  */
  81 static u32 wusbhc_next_tkid(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
  82 {
  83         u32 *tkid;
  84         u32 addr;
  85
  86         if (wusb_dev == NULL) {
  87                 tkid = &wusbhc->gtk_tkid;
  88                 addr = 0;
  89         } else {
  90                 tkid = &wusb_port_by_idx(wusbhc, wusb_dev->port_idx)->ptk_tkid;
  91                 addr = wusb_dev->addr & 0x7f;
  92         }
  93
  94         *tkid = (addr << 8) | ((*tkid + 1) & 0xff);
  95
  96         return *tkid;
  97 }
  98
  99 static void wusbhc_generate_gtk(struct wusbhc *wusbhc)
 100 {
 101         const size_t key_size = sizeof(wusbhc->gtk.data);
 102         u32 tkid;
 103
 104         tkid = wusbhc_next_tkid(wusbhc, NULL);
 105
 106         wusbhc->gtk.descr.tTKID[0] = (tkid >>  0) & 0xff;
 107         wusbhc->gtk.descr.tTKID[1] = (tkid >>  8) & 0xff;
 108         wusbhc->gtk.descr.tTKID[2] = (tkid >> 16) & 0xff;
 109
 110         get_random_bytes(wusbhc->gtk.descr.bKeyData, key_size);
 111 }
 112
 113 /**
 114  * wusbhc_sec_start - start the security management process
 115  * @wusbhc: the WUSB host controller
 116  *
 117  * Generate and set an initial GTK on the host controller.
 118  *
 119  * Called when the HC is started.
 120  */
 121 int wusbhc_sec_start(struct wusbhc *wusbhc)
 122 {
 123         const size_t key_size = sizeof(wusbhc->gtk.data);
 124         int result;
 125
 126         wusbhc_generate_gtk(wusbhc);
 127
 128         result = wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid,
 129                                 &wusbhc->gtk.descr.bKeyData, key_size);
 130         if (result < 0)
 131                 dev_err(wusbhc->dev, "cannot set GTK for the host: %d\n",
 132                         result);
 133
 134         return result;
 135 }
 136
 137 /**
 138  * wusbhc_sec_stop - stop the security management process
 139  * @wusbhc: the WUSB host controller
 140  *
 141  * Wait for any pending GTK rekeys to stop.
 142  */
 143 void wusbhc_sec_stop(struct wusbhc *wusbhc)
 144 {
 145         cancel_work_sync(&wusbhc->gtk_rekey_work);
 146 }
 147
 148
 149 /** @returns encryption type name */
 150 const char *wusb_et_name(u8 x)
 151 {
 152         switch (x) {
 153         case USB_ENC_TYPE_UNSECURE:     return "unsecure";
 154         case USB_ENC_TYPE_WIRED:        return "wired";
 155         case USB_ENC_TYPE_CCM_1:        return "CCM-1";
 156         case USB_ENC_TYPE_RSA_1:        return "RSA-1";
 157         default:                        return "unknown";
 158         }
 159 }
 160 EXPORT_SYMBOL_GPL(wusb_et_name);
 161
 162 /*
 163  * Set the device encryption method
 164  *
 165  * We tell the device which encryption method to use; we do this when
 166  * setting up the device's security.
 167  */
 168 static int wusb_dev_set_encryption(struct usb_device *usb_dev, int value)
 169 {
 170         int result;
 171         struct device *dev = &usb_dev->dev;
 172         struct wusb_dev *wusb_dev = usb_dev->wusb_dev;
 173
 174         if (value) {
 175                 value = wusb_dev->ccm1_etd.bEncryptionValue;
 176         } else {
 177                 /* FIXME: should be wusb_dev->etd[UNSECURE].bEncryptionValue */
 178                 value = 0;
 179         }
 180         /* Set device's */
 181         result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
 182                         USB_REQ_SET_ENCRYPTION,
 183                         USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 184                         value, 0, NULL, 0, USB_CTRL_SET_TIMEOUT);
 185         if (result < 0)
 186                 dev_err(dev, "Can't set device's WUSB encryption to "
 187                         "%s (value %d): %d\n",
 188                         wusb_et_name(wusb_dev->ccm1_etd.bEncryptionType),
 189                         wusb_dev->ccm1_etd.bEncryptionValue,  result);
 190         return result;
 191 }
 192
 193 /*
 194  * Set the GTK to be used by a device.
 195  *
 196  * The device must be authenticated.
 197  */
 198 static int wusb_dev_set_gtk(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
 199 {
 200         struct usb_device *usb_dev = wusb_dev->usb_dev;
 201         u8 key_index = wusb_key_index(wusbhc->gtk_index,
 202                 WUSB_KEY_INDEX_TYPE_GTK, WUSB_KEY_INDEX_ORIGINATOR_HOST);
 203
 204         return usb_control_msg(
 205                 usb_dev, usb_sndctrlpipe(usb_dev, 0),
 206                 USB_REQ_SET_DESCRIPTOR,
 207                 USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 208                 USB_DT_KEY << 8 | key_index, 0,
 209                 &wusbhc->gtk.descr, wusbhc->gtk.descr.bLength,
 210                 USB_CTRL_SET_TIMEOUT);
 211 }
 212
 213
 214 /* FIXME: prototype for adding security */
 215 int wusb_dev_sec_add(struct wusbhc *wusbhc,
 216                      struct usb_device *usb_dev, struct wusb_dev *wusb_dev)
 217 {
 218         int result, bytes, secd_size;
 219         struct device *dev = &usb_dev->dev;
 220         struct usb_security_descriptor *secd, *new_secd;
 221         const struct usb_encryption_descriptor *etd, *ccm1_etd = NULL;
 222         const void *itr, *top;
 223         char buf[64];
 224
 225         secd = kmalloc(sizeof(*secd), GFP_KERNEL);
 226         if (secd == NULL) {
 227                 result = -ENOMEM;
 228                 goto out;
 229         }
 230
 231         result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
 232                                     0, secd, sizeof(*secd));
 233         if (result < sizeof(*secd)) {
 234                 dev_err(dev, "Can't read security descriptor or "
 235                         "not enough data: %d\n", result);
 236                 goto out;
 237         }
 238         secd_size = le16_to_cpu(secd->wTotalLength);
 239         new_secd = krealloc(secd, secd_size, GFP_KERNEL);
 240         if (new_secd == NULL) {
 241                 dev_err(dev,
 242                         "Can't allocate space for security descriptors\n");
 243                 goto out;
 244         }
 245         secd = new_secd;
 246         result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
 247                                     0, secd, secd_size);
 248         if (result < secd_size) {
 249                 dev_err(dev, "Can't read security descriptor or "
 250                         "not enough data: %d\n", result);
 251                 goto out;
 252         }
 253         bytes = 0;
 254         itr = &secd[1];
 255         top = (void *)secd + result;
 256         while (itr < top) {
 257                 etd = itr;
 258                 if (top - itr < sizeof(*etd)) {
 259                         dev_err(dev, "BUG: bad device security descriptor; "
 260                                 "not enough data (%zu vs %zu bytes left)\n",
 261                                 top - itr, sizeof(*etd));
 262                         break;
 263                 }
 264                 if (etd->bLength < sizeof(*etd)) {
 265                         dev_err(dev, "BUG: bad device encryption descriptor; "
 266                                 "descriptor is too short "
 267                                 "(%u vs %zu needed)\n",
 268                                 etd->bLength, sizeof(*etd));
 269                         break;
 270                 }
 271                 itr += etd->bLength;
 272                 bytes += snprintf(buf + bytes, sizeof(buf) - bytes,
 273                                   "%s (0x%02x/%02x) ",
 274                                   wusb_et_name(etd->bEncryptionType),
 275                                   etd->bEncryptionValue, etd->bAuthKeyIndex);
 276                 if (etd->bEncryptionType == USB_ENC_TYPE_CCM_1)
 277                         ccm1_etd = etd;
 278         }
 279         /* This code only supports CCM1 as of now. */
 280         /* FIXME: user has to choose which sec mode to use?
 281          * In theory we want CCM */
 282         if (ccm1_etd == NULL) {
 283                 dev_err(dev, "WUSB device doesn't support CCM1 encryption, "
 284                         "can't use!\n");
 285                 result = -EINVAL;
 286                 goto out;
 287         }
 288         wusb_dev->ccm1_etd = *ccm1_etd;
 289         dev_dbg(dev, "supported encryption: %s; using %s (0x%02x/%02x)\n",
 290                 buf, wusb_et_name(ccm1_etd->bEncryptionType),
 291                 ccm1_etd->bEncryptionValue, ccm1_etd->bAuthKeyIndex);
 292         result = 0;
 293 out:
 294         kfree(secd);
 295         return result;
 296 }
 297
 298 void wusb_dev_sec_rm(struct wusb_dev *wusb_dev)
 299 {
 300         /* Nothing so far */
 301 }
 302
 303 /**
 304  * Update the address of an unauthenticated WUSB device
 305  *
 306  * Once we have successfully authenticated, we take it to addr0 state
 307  * and then to a normal address.
 308  *
 309  * Before the device's address (as known by it) was usb_dev->devnum |
 310  * 0x80 (unauthenticated address). With this we update it to usb_dev->devnum.
 311  */
 312 int wusb_dev_update_address(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
 313 {
 314         int result = -ENOMEM;
 315         struct usb_device *usb_dev = wusb_dev->usb_dev;
 316         struct device *dev = &usb_dev->dev;
 317         u8 new_address = wusb_dev->addr & 0x7F;
 318
 319         /* Set address 0 */
 320         result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
 321                         USB_REQ_SET_ADDRESS,
 322                         USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 323                          0, 0, NULL, 0, USB_CTRL_SET_TIMEOUT);
 324         if (result < 0) {
 325                 dev_err(dev, "auth failed: can't set address 0: %d\n",
 326                         result);
 327                 goto error_addr0;
 328         }
 329         result = wusb_set_dev_addr(wusbhc, wusb_dev, 0);
 330         if (result < 0)
 331                 goto error_addr0;
 332         usb_set_device_state(usb_dev, USB_STATE_DEFAULT);
 333         usb_ep0_reinit(usb_dev);
 334
 335         /* Set new (authenticated) address. */
 336         result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
 337                         USB_REQ_SET_ADDRESS,
 338                         USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 339                         new_address, 0, NULL, 0,
 340                         USB_CTRL_SET_TIMEOUT);
 341         if (result < 0) {
 342                 dev_err(dev, "auth failed: can't set address %u: %d\n",
 343                         new_address, result);
 344                 goto error_addr;
 345         }
 346         result = wusb_set_dev_addr(wusbhc, wusb_dev, new_address);
 347         if (result < 0)
 348                 goto error_addr;
 349         usb_set_device_state(usb_dev, USB_STATE_ADDRESS);
 350         usb_ep0_reinit(usb_dev);
 351         usb_dev->authenticated = 1;
 352 error_addr:
 353 error_addr0:
 354         return result;
 355 }
 356
 357 /*
 358  *
 359  *
 360  */
 361 /* FIXME: split and cleanup */
 362 int wusb_dev_4way_handshake(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev,
 363                             struct wusb_ckhdid *ck)
 364 {
 365         int result = -ENOMEM;
 366         struct usb_device *usb_dev = wusb_dev->usb_dev;
 367         struct device *dev = &usb_dev->dev;
 368         u32 tkid;
 369         __le32 tkid_le;
 370         struct usb_handshake *hs;
 371         struct aes_ccm_nonce ccm_n;
 372         u8 mic[8];
 373         struct wusb_keydvt_in keydvt_in;
 374         struct wusb_keydvt_out keydvt_out;
 375
 376         hs = kcalloc(3, sizeof(hs[0]), GFP_KERNEL);
 377         if (hs == NULL) {
 378                 dev_err(dev, "can't allocate handshake data\n");
 379                 goto error_kzalloc;
 380         }
 381
 382         /* We need to turn encryption before beginning the 4way
 383          * hshake (WUSB1.0[.3.2.2]) */
 384         result = wusb_dev_set_encryption(usb_dev, 1);
 385         if (result < 0)
 386                 goto error_dev_set_encryption;
 387
 388         tkid = wusbhc_next_tkid(wusbhc, wusb_dev);
 389         tkid_le = cpu_to_le32(tkid);
 390
 391         hs[0].bMessageNumber = 1;
 392         hs[0].bStatus = 0;
 393         memcpy(hs[0].tTKID, &tkid_le, sizeof(hs[0].tTKID));
 394         hs[0].bReserved = 0;
 395         memcpy(hs[0].CDID, &wusb_dev->cdid, sizeof(hs[0].CDID));
 396         get_random_bytes(&hs[0].nonce, sizeof(hs[0].nonce));
 397         memset(hs[0].MIC, 0, sizeof(hs[0].MIC)); /* Per WUSB1.0[T7-22] */
 398
 399         result = usb_control_msg(
 400                 usb_dev, usb_sndctrlpipe(usb_dev, 0),
 401                 USB_REQ_SET_HANDSHAKE,
 402                 USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 403                 1, 0, &hs[0], sizeof(hs[0]), USB_CTRL_SET_TIMEOUT);
 404         if (result < 0) {
 405                 dev_err(dev, "Handshake1: request failed: %d\n", result);
 406                 goto error_hs1;
 407         }
 408
 409         /* Handshake 2, from the device -- need to verify fields */
 410         result = usb_control_msg(
 411                 usb_dev, usb_rcvctrlpipe(usb_dev, 0),
 412                 USB_REQ_GET_HANDSHAKE,
 413                 USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 414                 2, 0, &hs[1], sizeof(hs[1]), USB_CTRL_GET_TIMEOUT);
 415         if (result < 0) {
 416                 dev_err(dev, "Handshake2: request failed: %d\n", result);
 417                 goto error_hs2;
 418         }
 419
 420         result = -EINVAL;
 421         if (hs[1].bMessageNumber != 2) {
 422                 dev_err(dev, "Handshake2 failed: bad message number %u\n",
 423                         hs[1].bMessageNumber);
 424                 goto error_hs2;
 425         }
 426         if (hs[1].bStatus != 0) {
 427                 dev_err(dev, "Handshake2 failed: bad status %u\n",
 428                         hs[1].bStatus);
 429                 goto error_hs2;
 430         }
 431         if (memcmp(hs[0].tTKID, hs[1].tTKID, sizeof(hs[0].tTKID))) {
 432                 dev_err(dev, "Handshake2 failed: TKID mismatch "
 433                         "(#1 0x%02x%02x%02x vs #2 0x%02x%02x%02x)\n",
 434                         hs[0].tTKID[0], hs[0].tTKID[1], hs[0].tTKID[2],
 435                         hs[1].tTKID[0], hs[1].tTKID[1], hs[1].tTKID[2]);
 436                 goto error_hs2;
 437         }
 438         if (memcmp(hs[0].CDID, hs[1].CDID, sizeof(hs[0].CDID))) {
 439                 dev_err(dev, "Handshake2 failed: CDID mismatch\n");
 440                 goto error_hs2;
 441         }
 442
 443         /* Setup the CCM nonce */
 444         memset(&ccm_n.sfn, 0, sizeof(ccm_n.sfn)); /* Per WUSB1.0[6.5.2] */
 445         memcpy(ccm_n.tkid, &tkid_le, sizeof(ccm_n.tkid));
 446         ccm_n.src_addr = wusbhc->uwb_rc->uwb_dev.dev_addr;
 447         ccm_n.dest_addr.data[0] = wusb_dev->addr;
 448         ccm_n.dest_addr.data[1] = 0;
 449
 450         /* Derive the KCK and PTK from CK, the CCM, H and D nonces */
 451         memcpy(keydvt_in.hnonce, hs[0].nonce, sizeof(keydvt_in.hnonce));
 452         memcpy(keydvt_in.dnonce, hs[1].nonce, sizeof(keydvt_in.dnonce));
 453         result = wusb_key_derive(&keydvt_out, ck->data, &ccm_n, &keydvt_in);
 454         if (result < 0) {
 455                 dev_err(dev, "Handshake2 failed: cannot derive keys: %d\n",
 456                         result);
 457                 goto error_hs2;
 458         }
 459
 460         /* Compute MIC and verify it */
 461         result = wusb_oob_mic(mic, keydvt_out.kck, &ccm_n, &hs[1]);
 462         if (result < 0) {
 463                 dev_err(dev, "Handshake2 failed: cannot compute MIC: %d\n",
 464                         result);
 465                 goto error_hs2;
 466         }
 467
 468         if (memcmp(hs[1].MIC, mic, sizeof(hs[1].MIC))) {
 469                 dev_err(dev, "Handshake2 failed: MIC mismatch\n");
 470                 goto error_hs2;
 471         }
 472
 473         /* Send Handshake3 */
 474         hs[2].bMessageNumber = 3;
 475         hs[2].bStatus = 0;
 476         memcpy(hs[2].tTKID, &tkid_le, sizeof(hs[2].tTKID));
 477         hs[2].bReserved = 0;
 478         memcpy(hs[2].CDID, &wusb_dev->cdid, sizeof(hs[2].CDID));
 479         memcpy(hs[2].nonce, hs[0].nonce, sizeof(hs[2].nonce));
 480         result = wusb_oob_mic(hs[2].MIC, keydvt_out.kck, &ccm_n, &hs[2]);
 481         if (result < 0) {
 482                 dev_err(dev, "Handshake3 failed: cannot compute MIC: %d\n",
 483                         result);
 484                 goto error_hs2;
 485         }
 486
 487         result = usb_control_msg(
 488                 usb_dev, usb_sndctrlpipe(usb_dev, 0),
 489                 USB_REQ_SET_HANDSHAKE,
 490                 USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 491                 3, 0, &hs[2], sizeof(hs[2]), USB_CTRL_SET_TIMEOUT);
 492         if (result < 0) {
 493                 dev_err(dev, "Handshake3: request failed: %d\n", result);
 494                 goto error_hs3;
 495         }
 496
 497         result = wusbhc->set_ptk(wusbhc, wusb_dev->port_idx, tkid,
 498                                  keydvt_out.ptk, sizeof(keydvt_out.ptk));
 499         if (result < 0)
 500                 goto error_wusbhc_set_ptk;
 501
 502         result = wusb_dev_set_gtk(wusbhc, wusb_dev);
 503         if (result < 0) {
 504                 dev_err(dev, "Set GTK for device: request failed: %d\n",
 505                         result);
 506                 goto error_wusbhc_set_gtk;
 507         }
 508
 509         /* Update the device's address from unauth to auth */
 510         if (usb_dev->authenticated == 0) {
 511                 result = wusb_dev_update_address(wusbhc, wusb_dev);
 512                 if (result < 0)
 513                         goto error_dev_update_address;
 514         }
 515         result = 0;
 516         dev_info(dev, "device authenticated\n");
 517
 518 error_dev_update_address:
 519 error_wusbhc_set_gtk:
 520 error_wusbhc_set_ptk:
 521 error_hs3:
 522 error_hs2:
 523 error_hs1:
 524         memset(hs, 0, 3*sizeof(hs[0]));
 525         memzero_explicit(&keydvt_out, sizeof(keydvt_out));
 526         memzero_explicit(&keydvt_in, sizeof(keydvt_in));
 527         memzero_explicit(&ccm_n, sizeof(ccm_n));
 528         memzero_explicit(mic, sizeof(mic));
 529         if (result < 0)
 530                 wusb_dev_set_encryption(usb_dev, 0);
 531 error_dev_set_encryption:
 532         kfree(hs);
 533 error_kzalloc:
 534         return result;
 535 }
 536
 537 /*
 538  * Once all connected and authenticated devices have received the new
 539  * GTK, switch the host to using it.
 540  */
 541 static void wusbhc_gtk_rekey_work(struct work_struct *work)
 542 {
 543         struct wusbhc *wusbhc = container_of(work,
 544                                         struct wusbhc, gtk_rekey_work);
 545         size_t key_size = sizeof(wusbhc->gtk.data);
 546         int port_idx;
 547         struct wusb_dev *wusb_dev, *wusb_dev_next;
 548         LIST_HEAD(rekey_list);
 549
 550         mutex_lock(&wusbhc->mutex);
 551         /* generate the new key */
 552         wusbhc_generate_gtk(wusbhc);
 553         /* roll the gtk index. */
 554         wusbhc->gtk_index = (wusbhc->gtk_index + 1) % (WUSB_KEY_INDEX_MAX + 1);
 555         /*
 556          * Save all connected devices on a list while holding wusbhc->mutex and
 557          * take a reference to each one.  Then submit the set key request to
 558          * them after releasing the lock in order to avoid a deadlock.
 559          */
 560         for (port_idx = 0; port_idx < wusbhc->ports_max; port_idx++) {
 561                 wusb_dev = wusbhc->port[port_idx].wusb_dev;
 562                 if (!wusb_dev || !wusb_dev->usb_dev
 563                         || !wusb_dev->usb_dev->authenticated)
 564                         continue;
 565
 566                 wusb_dev_get(wusb_dev);
 567                 list_add_tail(&wusb_dev->rekey_node, &rekey_list);
 568         }
 569         mutex_unlock(&wusbhc->mutex);
 570
 571         /* Submit the rekey requests without holding wusbhc->mutex. */
 572         list_for_each_entry_safe(wusb_dev, wusb_dev_next, &rekey_list,
 573                 rekey_node) {
 574                 list_del_init(&wusb_dev->rekey_node);
 575                 dev_dbg(&wusb_dev->usb_dev->dev,
 576                         "%s: rekey device at port %d\n",
 577                         __func__, wusb_dev->port_idx);
 578
 579                 if (wusb_dev_set_gtk(wusbhc, wusb_dev) < 0) {
 580                         dev_err(&wusb_dev->usb_dev->dev,
 581                                 "%s: rekey device at port %d failed\n",
 582                                 __func__, wusb_dev->port_idx);
 583                 }
 584                 wusb_dev_put(wusb_dev);
 585         }
 586
 587         /* Switch the host controller to use the new GTK. */
 588         mutex_lock(&wusbhc->mutex);
 589         wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid,
 590                 &wusbhc->gtk.descr.bKeyData, key_size);
 591         mutex_unlock(&wusbhc->mutex);
 592 }
 593
 594 /**
 595  * wusbhc_gtk_rekey - generate and distribute a new GTK
 596  * @wusbhc: the WUSB host controller
 597  *
 598  * Generate a new GTK and distribute it to all connected and
 599  * authenticated devices.  When all devices have the new GTK, the host
 600  * starts using it.
 601  *
 602  * This must be called after every device disconnect (see [WUSB]
 603  * section 6.2.11.2).
 604  */
 605 void wusbhc_gtk_rekey(struct wusbhc *wusbhc)
 606 {
 607         /*
 608          * We need to submit a URB to the downstream WUSB devices in order to
 609          * change the group key.  This can't be done while holding the
 610          * wusbhc->mutex since that is also taken in the urb_enqueue routine
 611          * and will cause a deadlock.  Instead, queue a work item to do
 612          * it when the lock is not held
 613          */
 614         queue_work(wusbhc->wq_security, &wusbhc->gtk_rekey_work);
 615 }