root/drivers/staging/wusbcore/security.c

DEFINITIONS

1. wusbhc_sec_create
2. wusbhc_sec_destroy
3. wusbhc_next_tkid
4. wusbhc_generate_gtk
5. wusbhc_sec_start
6. wusbhc_sec_stop
7. wusb_et_name
8. wusb_dev_set_encryption
9. wusb_dev_set_gtk
10. wusb_dev_sec_add
11. wusb_dev_sec_rm
12. wusb_dev_update_address
13. wusb_dev_4way_handshake
14. wusbhc_gtk_rekey_work
15. wusbhc_gtk_rekey

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Wireless USB Host Controller
   4  * Security support: encryption enablement, etc
   5  *
   6  * Copyright (C) 2006 Intel Corporation
   7  * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
   8  *
   9  * FIXME: docs
  10  */
  11 #include <linux/types.h>
  12 #include <linux/slab.h>
  13 #include <linux/usb/ch9.h>
  14 #include <linux/random.h>
  15 #include <linux/export.h>
  16 #include "wusbhc.h"
  17 #include <asm/unaligned.h>
  18 
  19 static void wusbhc_gtk_rekey_work(struct work_struct *work);
  20 
  21 int wusbhc_sec_create(struct wusbhc *wusbhc)
  22 {
  23         /*
  24          * WQ is singlethread because we need to serialize rekey operations.
  25          * Use a separate workqueue for security operations instead of the
  26          * wusbd workqueue because security operations may need to communicate
  27          * directly with downstream wireless devices using synchronous URBs.
  28          * If a device is not responding, this could block other host
  29          * controller operations.
  30          */
  31         wusbhc->wq_security = create_singlethread_workqueue("wusbd_security");
  32         if (wusbhc->wq_security == NULL) {
  33                 pr_err("WUSB-core: Cannot create wusbd_security workqueue\n");
  34                 return -ENOMEM;
  35         }
  36 
  37         wusbhc->gtk.descr.bLength = sizeof(wusbhc->gtk.descr) +
  38                 sizeof(wusbhc->gtk.data);
  39         wusbhc->gtk.descr.bDescriptorType = USB_DT_KEY;
  40         wusbhc->gtk.descr.bReserved = 0;
  41         wusbhc->gtk_index = 0;
  42 
  43         INIT_WORK(&wusbhc->gtk_rekey_work, wusbhc_gtk_rekey_work);
  44 
  45         return 0;
  46 }
  47 
  48 
  49 /* Called when the HC is destroyed */
  50 void wusbhc_sec_destroy(struct wusbhc *wusbhc)
  51 {
  52         destroy_workqueue(wusbhc->wq_security);
  53 }
  54 
  55 
  56 /**
  57  * wusbhc_next_tkid - generate a new, currently unused, TKID
  58  * @wusbhc:   the WUSB host controller
  59  * @wusb_dev: the device whose PTK the TKID is for
  60  *            (or NULL for a TKID for a GTK)
  61  *
  62  * The generated TKID consists of two parts: the device's authenticated
  63  * address (or 0 or a GTK); and an incrementing number.  This ensures
  64  * that TKIDs cannot be shared between devices and by the time the
  65  * incrementing number wraps around the older TKIDs will no longer be
  66  * in use (a maximum of two keys may be active at any one time).
  67  */
  68 static u32 wusbhc_next_tkid(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
  69 {
  70         u32 *tkid;
  71         u32 addr;
  72 
  73         if (wusb_dev == NULL) {
  74                 tkid = &wusbhc->gtk_tkid;
  75                 addr = 0;
  76         } else {
  77                 tkid = &wusb_port_by_idx(wusbhc, wusb_dev->port_idx)->ptk_tkid;
  78                 addr = wusb_dev->addr & 0x7f;
  79         }
  80 
  81         *tkid = (addr << 8) | ((*tkid + 1) & 0xff);
  82 
  83         return *tkid;
  84 }
  85 
  86 static void wusbhc_generate_gtk(struct wusbhc *wusbhc)
  87 {
  88         const size_t key_size = sizeof(wusbhc->gtk.data);
  89         u32 tkid;
  90 
  91         tkid = wusbhc_next_tkid(wusbhc, NULL);
  92 
  93         wusbhc->gtk.descr.tTKID[0] = (tkid >>  0) & 0xff;
  94         wusbhc->gtk.descr.tTKID[1] = (tkid >>  8) & 0xff;
  95         wusbhc->gtk.descr.tTKID[2] = (tkid >> 16) & 0xff;
  96 
  97         get_random_bytes(wusbhc->gtk.descr.bKeyData, key_size);
  98 }
  99 
 100 /**
 101  * wusbhc_sec_start - start the security management process
 102  * @wusbhc: the WUSB host controller
 103  *
 104  * Generate and set an initial GTK on the host controller.
 105  *
 106  * Called when the HC is started.
 107  */
 108 int wusbhc_sec_start(struct wusbhc *wusbhc)
 109 {
 110         const size_t key_size = sizeof(wusbhc->gtk.data);
 111         int result;
 112 
 113         wusbhc_generate_gtk(wusbhc);
 114 
 115         result = wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid,
 116                                 &wusbhc->gtk.descr.bKeyData, key_size);
 117         if (result < 0)
 118                 dev_err(wusbhc->dev, "cannot set GTK for the host: %d\n",
 119                         result);
 120 
 121         return result;
 122 }
 123 
 124 /**
 125  * wusbhc_sec_stop - stop the security management process
 126  * @wusbhc: the WUSB host controller
 127  *
 128  * Wait for any pending GTK rekeys to stop.
 129  */
 130 void wusbhc_sec_stop(struct wusbhc *wusbhc)
 131 {
 132         cancel_work_sync(&wusbhc->gtk_rekey_work);
 133 }
 134 
 135 
 136 /** @returns encryption type name */
 137 const char *wusb_et_name(u8 x)
 138 {
 139         switch (x) {
 140         case USB_ENC_TYPE_UNSECURE:     return "unsecure";
 141         case USB_ENC_TYPE_WIRED:        return "wired";
 142         case USB_ENC_TYPE_CCM_1:        return "CCM-1";
 143         case USB_ENC_TYPE_RSA_1:        return "RSA-1";
 144         default:                        return "unknown";
 145         }
 146 }
 147 EXPORT_SYMBOL_GPL(wusb_et_name);
 148 
 149 /*
 150  * Set the device encryption method
 151  *
 152  * We tell the device which encryption method to use; we do this when
 153  * setting up the device's security.
 154  */
 155 static int wusb_dev_set_encryption(struct usb_device *usb_dev, int value)
 156 {
 157         int result;
 158         struct device *dev = &usb_dev->dev;
 159         struct wusb_dev *wusb_dev = usb_dev->wusb_dev;
 160 
 161         if (value) {
 162                 value = wusb_dev->ccm1_etd.bEncryptionValue;
 163         } else {
 164                 /* FIXME: should be wusb_dev->etd[UNSECURE].bEncryptionValue */
 165                 value = 0;
 166         }
 167         /* Set device's */
 168         result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
 169                         USB_REQ_SET_ENCRYPTION,
 170                         USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 171                         value, 0, NULL, 0, USB_CTRL_SET_TIMEOUT);
 172         if (result < 0)
 173                 dev_err(dev, "Can't set device's WUSB encryption to "
 174                         "%s (value %d): %d\n",
 175                         wusb_et_name(wusb_dev->ccm1_etd.bEncryptionType),
 176                         wusb_dev->ccm1_etd.bEncryptionValue,  result);
 177         return result;
 178 }
 179 
 180 /*
 181  * Set the GTK to be used by a device.
 182  *
 183  * The device must be authenticated.
 184  */
 185 static int wusb_dev_set_gtk(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
 186 {
 187         struct usb_device *usb_dev = wusb_dev->usb_dev;
 188         u8 key_index = wusb_key_index(wusbhc->gtk_index,
 189                 WUSB_KEY_INDEX_TYPE_GTK, WUSB_KEY_INDEX_ORIGINATOR_HOST);
 190 
 191         return usb_control_msg(
 192                 usb_dev, usb_sndctrlpipe(usb_dev, 0),
 193                 USB_REQ_SET_DESCRIPTOR,
 194                 USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 195                 USB_DT_KEY << 8 | key_index, 0,
 196                 &wusbhc->gtk.descr, wusbhc->gtk.descr.bLength,
 197                 USB_CTRL_SET_TIMEOUT);
 198 }
 199 
 200 
 201 /* FIXME: prototype for adding security */
 202 int wusb_dev_sec_add(struct wusbhc *wusbhc,
 203                      struct usb_device *usb_dev, struct wusb_dev *wusb_dev)
 204 {
 205         int result, bytes, secd_size;
 206         struct device *dev = &usb_dev->dev;
 207         struct usb_security_descriptor *secd, *new_secd;
 208         const struct usb_encryption_descriptor *etd, *ccm1_etd = NULL;
 209         const void *itr, *top;
 210         char buf[64];
 211 
 212         secd = kmalloc(sizeof(*secd), GFP_KERNEL);
 213         if (secd == NULL) {
 214                 result = -ENOMEM;
 215                 goto out;
 216         }
 217 
 218         result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
 219                                     0, secd, sizeof(*secd));
 220         if (result < (int)sizeof(*secd)) {
 221                 dev_err(dev, "Can't read security descriptor or "
 222                         "not enough data: %d\n", result);
 223                 goto out;
 224         }
 225         secd_size = le16_to_cpu(secd->wTotalLength);
 226         new_secd = krealloc(secd, secd_size, GFP_KERNEL);
 227         if (new_secd == NULL) {
 228                 dev_err(dev,
 229                         "Can't allocate space for security descriptors\n");
 230                 result = -ENOMEM;
 231                 goto out;
 232         }
 233         secd = new_secd;
 234         result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
 235                                     0, secd, secd_size);
 236         if (result < secd_size) {
 237                 dev_err(dev, "Can't read security descriptor or "
 238                         "not enough data: %d\n", result);
 239                 goto out;
 240         }
 241         bytes = 0;
 242         itr = &secd[1];
 243         top = (void *)secd + result;
 244         while (itr < top) {
 245                 etd = itr;
 246                 if (top - itr < sizeof(*etd)) {
 247                         dev_err(dev, "BUG: bad device security descriptor; "
 248                                 "not enough data (%zu vs %zu bytes left)\n",
 249                                 top - itr, sizeof(*etd));
 250                         break;
 251                 }
 252                 if (etd->bLength < sizeof(*etd)) {
 253                         dev_err(dev, "BUG: bad device encryption descriptor; "
 254                                 "descriptor is too short "
 255                                 "(%u vs %zu needed)\n",
 256                                 etd->bLength, sizeof(*etd));
 257                         break;
 258                 }
 259                 itr += etd->bLength;
 260                 bytes += snprintf(buf + bytes, sizeof(buf) - bytes,
 261                                   "%s (0x%02x/%02x) ",
 262                                   wusb_et_name(etd->bEncryptionType),
 263                                   etd->bEncryptionValue, etd->bAuthKeyIndex);
 264                 if (etd->bEncryptionType == USB_ENC_TYPE_CCM_1)
 265                         ccm1_etd = etd;
 266         }
 267         /* This code only supports CCM1 as of now. */
 268         /* FIXME: user has to choose which sec mode to use?
 269          * In theory we want CCM */
 270         if (ccm1_etd == NULL) {
 271                 dev_err(dev, "WUSB device doesn't support CCM1 encryption, "
 272                         "can't use!\n");
 273                 result = -EINVAL;
 274                 goto out;
 275         }
 276         wusb_dev->ccm1_etd = *ccm1_etd;
 277         dev_dbg(dev, "supported encryption: %s; using %s (0x%02x/%02x)\n",
 278                 buf, wusb_et_name(ccm1_etd->bEncryptionType),
 279                 ccm1_etd->bEncryptionValue, ccm1_etd->bAuthKeyIndex);
 280         result = 0;
 281 out:
 282         kfree(secd);
 283         return result;
 284 }
 285 
 286 void wusb_dev_sec_rm(struct wusb_dev *wusb_dev)
 287 {
 288         /* Nothing so far */
 289 }
 290 
 291 /**
 292  * Update the address of an unauthenticated WUSB device
 293  *
 294  * Once we have successfully authenticated, we take it to addr0 state
 295  * and then to a normal address.
 296  *
 297  * Before the device's address (as known by it) was usb_dev->devnum |
 298  * 0x80 (unauthenticated address). With this we update it to usb_dev->devnum.
 299  */
 300 int wusb_dev_update_address(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
 301 {
 302         int result = -ENOMEM;
 303         struct usb_device *usb_dev = wusb_dev->usb_dev;
 304         struct device *dev = &usb_dev->dev;
 305         u8 new_address = wusb_dev->addr & 0x7F;
 306 
 307         /* Set address 0 */
 308         result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
 309                         USB_REQ_SET_ADDRESS,
 310                         USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 311                          0, 0, NULL, 0, USB_CTRL_SET_TIMEOUT);
 312         if (result < 0) {
 313                 dev_err(dev, "auth failed: can't set address 0: %d\n",
 314                         result);
 315                 goto error_addr0;
 316         }
 317         result = wusb_set_dev_addr(wusbhc, wusb_dev, 0);
 318         if (result < 0)
 319                 goto error_addr0;
 320         usb_set_device_state(usb_dev, USB_STATE_DEFAULT);
 321         usb_ep0_reinit(usb_dev);
 322 
 323         /* Set new (authenticated) address. */
 324         result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
 325                         USB_REQ_SET_ADDRESS,
 326                         USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 327                         new_address, 0, NULL, 0,
 328                         USB_CTRL_SET_TIMEOUT);
 329         if (result < 0) {
 330                 dev_err(dev, "auth failed: can't set address %u: %d\n",
 331                         new_address, result);
 332                 goto error_addr;
 333         }
 334         result = wusb_set_dev_addr(wusbhc, wusb_dev, new_address);
 335         if (result < 0)
 336                 goto error_addr;
 337         usb_set_device_state(usb_dev, USB_STATE_ADDRESS);
 338         usb_ep0_reinit(usb_dev);
 339         usb_dev->authenticated = 1;
 340 error_addr:
 341 error_addr0:
 342         return result;
 343 }
 344 
 345 /*
 346  *
 347  *
 348  */
 349 /* FIXME: split and cleanup */
 350 int wusb_dev_4way_handshake(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev,
 351                             struct wusb_ckhdid *ck)
 352 {
 353         int result = -ENOMEM;
 354         struct usb_device *usb_dev = wusb_dev->usb_dev;
 355         struct device *dev = &usb_dev->dev;
 356         u32 tkid;
 357         struct usb_handshake *hs;
 358         struct aes_ccm_nonce ccm_n;
 359         u8 mic[8];
 360         struct wusb_keydvt_in keydvt_in;
 361         struct wusb_keydvt_out keydvt_out;
 362 
 363         hs = kcalloc(3, sizeof(hs[0]), GFP_KERNEL);
 364         if (!hs)
 365                 goto error_kzalloc;
 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 
 375         hs[0].bMessageNumber = 1;
 376         hs[0].bStatus = 0;
 377         put_unaligned_le32(tkid, hs[0].tTKID);
 378         hs[0].bReserved = 0;
 379         memcpy(hs[0].CDID, &wusb_dev->cdid, sizeof(hs[0].CDID));
 380         get_random_bytes(&hs[0].nonce, sizeof(hs[0].nonce));
 381         memset(hs[0].MIC, 0, sizeof(hs[0].MIC)); /* Per WUSB1.0[T7-22] */
 382 
 383         result = usb_control_msg(
 384                 usb_dev, usb_sndctrlpipe(usb_dev, 0),
 385                 USB_REQ_SET_HANDSHAKE,
 386                 USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 387                 1, 0, &hs[0], sizeof(hs[0]), USB_CTRL_SET_TIMEOUT);
 388         if (result < 0) {
 389                 dev_err(dev, "Handshake1: request failed: %d\n", result);
 390                 goto error_hs1;
 391         }
 392 
 393         /* Handshake 2, from the device -- need to verify fields */
 394         result = usb_control_msg(
 395                 usb_dev, usb_rcvctrlpipe(usb_dev, 0),
 396                 USB_REQ_GET_HANDSHAKE,
 397                 USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 398                 2, 0, &hs[1], sizeof(hs[1]), USB_CTRL_GET_TIMEOUT);
 399         if (result < 0) {
 400                 dev_err(dev, "Handshake2: request failed: %d\n", result);
 401                 goto error_hs2;
 402         }
 403 
 404         result = -EINVAL;
 405         if (hs[1].bMessageNumber != 2) {
 406                 dev_err(dev, "Handshake2 failed: bad message number %u\n",
 407                         hs[1].bMessageNumber);
 408                 goto error_hs2;
 409         }
 410         if (hs[1].bStatus != 0) {
 411                 dev_err(dev, "Handshake2 failed: bad status %u\n",
 412                         hs[1].bStatus);
 413                 goto error_hs2;
 414         }
 415         if (memcmp(hs[0].tTKID, hs[1].tTKID, sizeof(hs[0].tTKID))) {
 416                 dev_err(dev, "Handshake2 failed: TKID mismatch "
 417                         "(#1 0x%02x%02x%02x vs #2 0x%02x%02x%02x)\n",
 418                         hs[0].tTKID[0], hs[0].tTKID[1], hs[0].tTKID[2],
 419                         hs[1].tTKID[0], hs[1].tTKID[1], hs[1].tTKID[2]);
 420                 goto error_hs2;
 421         }
 422         if (memcmp(hs[0].CDID, hs[1].CDID, sizeof(hs[0].CDID))) {
 423                 dev_err(dev, "Handshake2 failed: CDID mismatch\n");
 424                 goto error_hs2;
 425         }
 426 
 427         /* Setup the CCM nonce */
 428         memset(&ccm_n.sfn, 0, sizeof(ccm_n.sfn)); /* Per WUSB1.0[6.5.2] */
 429         put_unaligned_le32(tkid, ccm_n.tkid);
 430         ccm_n.src_addr = wusbhc->uwb_rc->uwb_dev.dev_addr;
 431         ccm_n.dest_addr.data[0] = wusb_dev->addr;
 432         ccm_n.dest_addr.data[1] = 0;
 433 
 434         /* Derive the KCK and PTK from CK, the CCM, H and D nonces */
 435         memcpy(keydvt_in.hnonce, hs[0].nonce, sizeof(keydvt_in.hnonce));
 436         memcpy(keydvt_in.dnonce, hs[1].nonce, sizeof(keydvt_in.dnonce));
 437         result = wusb_key_derive(&keydvt_out, ck->data, &ccm_n, &keydvt_in);
 438         if (result < 0) {
 439                 dev_err(dev, "Handshake2 failed: cannot derive keys: %d\n",
 440                         result);
 441                 goto error_hs2;
 442         }
 443 
 444         /* Compute MIC and verify it */
 445         result = wusb_oob_mic(mic, keydvt_out.kck, &ccm_n, &hs[1]);
 446         if (result < 0) {
 447                 dev_err(dev, "Handshake2 failed: cannot compute MIC: %d\n",
 448                         result);
 449                 goto error_hs2;
 450         }
 451 
 452         if (memcmp(hs[1].MIC, mic, sizeof(hs[1].MIC))) {
 453                 dev_err(dev, "Handshake2 failed: MIC mismatch\n");
 454                 goto error_hs2;
 455         }
 456 
 457         /* Send Handshake3 */
 458         hs[2].bMessageNumber = 3;
 459         hs[2].bStatus = 0;
 460         put_unaligned_le32(tkid, hs[2].tTKID);
 461         hs[2].bReserved = 0;
 462         memcpy(hs[2].CDID, &wusb_dev->cdid, sizeof(hs[2].CDID));
 463         memcpy(hs[2].nonce, hs[0].nonce, sizeof(hs[2].nonce));
 464         result = wusb_oob_mic(hs[2].MIC, keydvt_out.kck, &ccm_n, &hs[2]);
 465         if (result < 0) {
 466                 dev_err(dev, "Handshake3 failed: cannot compute MIC: %d\n",
 467                         result);
 468                 goto error_hs2;
 469         }
 470 
 471         result = usb_control_msg(
 472                 usb_dev, usb_sndctrlpipe(usb_dev, 0),
 473                 USB_REQ_SET_HANDSHAKE,
 474                 USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
 475                 3, 0, &hs[2], sizeof(hs[2]), USB_CTRL_SET_TIMEOUT);
 476         if (result < 0) {
 477                 dev_err(dev, "Handshake3: request failed: %d\n", result);
 478                 goto error_hs3;
 479         }
 480 
 481         result = wusbhc->set_ptk(wusbhc, wusb_dev->port_idx, tkid,
 482                                  keydvt_out.ptk, sizeof(keydvt_out.ptk));
 483         if (result < 0)
 484                 goto error_wusbhc_set_ptk;
 485 
 486         result = wusb_dev_set_gtk(wusbhc, wusb_dev);
 487         if (result < 0) {
 488                 dev_err(dev, "Set GTK for device: request failed: %d\n",
 489                         result);
 490                 goto error_wusbhc_set_gtk;
 491         }
 492 
 493         /* Update the device's address from unauth to auth */
 494         if (usb_dev->authenticated == 0) {
 495                 result = wusb_dev_update_address(wusbhc, wusb_dev);
 496                 if (result < 0)
 497                         goto error_dev_update_address;
 498         }
 499         result = 0;
 500         dev_info(dev, "device authenticated\n");
 501 
 502 error_dev_update_address:
 503 error_wusbhc_set_gtk:
 504 error_wusbhc_set_ptk:
 505 error_hs3:
 506 error_hs2:
 507 error_hs1:
 508         memset(hs, 0, 3*sizeof(hs[0]));
 509         memzero_explicit(&keydvt_out, sizeof(keydvt_out));
 510         memzero_explicit(&keydvt_in, sizeof(keydvt_in));
 511         memzero_explicit(&ccm_n, sizeof(ccm_n));
 512         memzero_explicit(mic, sizeof(mic));
 513         if (result < 0)
 514                 wusb_dev_set_encryption(usb_dev, 0);
 515 error_dev_set_encryption:
 516         kfree(hs);
 517 error_kzalloc:
 518         return result;
 519 }
 520 
 521 /*
 522  * Once all connected and authenticated devices have received the new
 523  * GTK, switch the host to using it.
 524  */
 525 static void wusbhc_gtk_rekey_work(struct work_struct *work)
 526 {
 527         struct wusbhc *wusbhc = container_of(work,
 528                                         struct wusbhc, gtk_rekey_work);
 529         size_t key_size = sizeof(wusbhc->gtk.data);
 530         int port_idx;
 531         struct wusb_dev *wusb_dev, *wusb_dev_next;
 532         LIST_HEAD(rekey_list);
 533 
 534         mutex_lock(&wusbhc->mutex);
 535         /* generate the new key */
 536         wusbhc_generate_gtk(wusbhc);
 537         /* roll the gtk index. */
 538         wusbhc->gtk_index = (wusbhc->gtk_index + 1) % (WUSB_KEY_INDEX_MAX + 1);
 539         /*
 540          * Save all connected devices on a list while holding wusbhc->mutex and
 541          * take a reference to each one.  Then submit the set key request to
 542          * them after releasing the lock in order to avoid a deadlock.
 543          */
 544         for (port_idx = 0; port_idx < wusbhc->ports_max; port_idx++) {
 545                 wusb_dev = wusbhc->port[port_idx].wusb_dev;
 546                 if (!wusb_dev || !wusb_dev->usb_dev
 547                         || !wusb_dev->usb_dev->authenticated)
 548                         continue;
 549 
 550                 wusb_dev_get(wusb_dev);
 551                 list_add_tail(&wusb_dev->rekey_node, &rekey_list);
 552         }
 553         mutex_unlock(&wusbhc->mutex);
 554 
 555         /* Submit the rekey requests without holding wusbhc->mutex. */
 556         list_for_each_entry_safe(wusb_dev, wusb_dev_next, &rekey_list,
 557                 rekey_node) {
 558                 list_del_init(&wusb_dev->rekey_node);
 559                 dev_dbg(&wusb_dev->usb_dev->dev,
 560                         "%s: rekey device at port %d\n",
 561                         __func__, wusb_dev->port_idx);
 562 
 563                 if (wusb_dev_set_gtk(wusbhc, wusb_dev) < 0) {
 564                         dev_err(&wusb_dev->usb_dev->dev,
 565                                 "%s: rekey device at port %d failed\n",
 566                                 __func__, wusb_dev->port_idx);
 567                 }
 568                 wusb_dev_put(wusb_dev);
 569         }
 570 
 571         /* Switch the host controller to use the new GTK. */
 572         mutex_lock(&wusbhc->mutex);
 573         wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid,
 574                 &wusbhc->gtk.descr.bKeyData, key_size);
 575         mutex_unlock(&wusbhc->mutex);
 576 }
 577 
 578 /**
 579  * wusbhc_gtk_rekey - generate and distribute a new GTK
 580  * @wusbhc: the WUSB host controller
 581  *
 582  * Generate a new GTK and distribute it to all connected and
 583  * authenticated devices.  When all devices have the new GTK, the host
 584  * starts using it.
 585  *
 586  * This must be called after every device disconnect (see [WUSB]
 587  * section 6.2.11.2).
 588  */
 589 void wusbhc_gtk_rekey(struct wusbhc *wusbhc)
 590 {
 591         /*
 592          * We need to submit a URB to the downstream WUSB devices in order to
 593          * change the group key.  This can't be done while holding the
 594          * wusbhc->mutex since that is also taken in the urb_enqueue routine
 595          * and will cause a deadlock.  Instead, queue a work item to do
 596          * it when the lock is not held
 597          */
 598         queue_work(wusbhc->wq_security, &wusbhc->gtk_rekey_work);
 599 }