hw/tpm/tpm_passthrough.c

   1 /*
   2  *  passthrough TPM driver
   3  *
   4  *  Copyright (c) 2010 - 2013 IBM Corporation
   5  *  Authors:
   6  *    Stefan Berger <stefanb@us.ibm.com>
   7  *
   8  *  Copyright (C) 2011 IAIK, Graz University of Technology
   9  *    Author: Andreas Niederl
  10  *
  11  * This library is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU Lesser General Public
  13  * License as published by the Free Software Foundation; either
  14  * version 2 of the License, or (at your option) any later version.
  15  *
  16  * This library is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19  * Lesser General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public
  22  * License along with this library; if not, see <http://www.gnu.org/licenses/>
  23  */
  24
  25 #include <dirent.h>
  26
  27 #include "qemu-common.h"
  28 #include "qapi/error.h"
  29 #include "qemu/sockets.h"
  30 #include "backends/tpm.h"
  31 #include "tpm_int.h"
  32 #include "hw/hw.h"
  33 #include "hw/i386/pc.h"
  34 #include "sysemu/tpm_backend_int.h"
  35 #include "tpm_tis.h"
  36
  37 /* #define DEBUG_TPM */
  38
  39 #ifdef DEBUG_TPM
  40 #define DPRINTF(fmt, ...) \
  41     do { fprintf(stderr, fmt, ## __VA_ARGS__); } while (0)
  42 #else
  43 #define DPRINTF(fmt, ...) \
  44     do { } while (0)
  45 #endif
  46
  47 #define TYPE_TPM_PASSTHROUGH "tpm-passthrough"
  48 #define TPM_PASSTHROUGH(obj) \
  49     OBJECT_CHECK(TPMPassthruState, (obj), TYPE_TPM_PASSTHROUGH)
  50
  51 static const TPMDriverOps tpm_passthrough_driver;
  52
  53 /* data structures */
  54 typedef struct TPMPassthruThreadParams {
  55     TPMState *tpm_state;
  56
  57     TPMRecvDataCB *recv_data_callback;
  58     TPMBackend *tb;
  59 } TPMPassthruThreadParams;
  60
  61 struct TPMPassthruState {
  62     TPMBackend parent;
  63
  64     TPMBackendThread tbt;
  65
  66     TPMPassthruThreadParams tpm_thread_params;
  67
  68     char *tpm_dev;
  69     int tpm_fd;
  70     bool tpm_executing;
  71     bool tpm_op_canceled;
  72     int cancel_fd;
  73     bool had_startup_error;
  74 };
  75
  76 typedef struct TPMPassthruState TPMPassthruState;
  77
  78 #define TPM_PASSTHROUGH_DEFAULT_DEVICE "/dev/tpm0"
  79
  80 /* functions */
  81
  82 static void tpm_passthrough_cancel_cmd(TPMBackend *tb);
  83
  84 static int tpm_passthrough_unix_write(int fd, const uint8_t *buf, uint32_t len)
  85 {
  86     return send_all(fd, buf, len);
  87 }
  88
  89 static int tpm_passthrough_unix_read(int fd, uint8_t *buf, uint32_t len)
  90 {
  91     return recv_all(fd, buf, len, true);
  92 }
  93
  94 static uint32_t tpm_passthrough_get_size_from_buffer(const uint8_t *buf)
  95 {
  96     struct tpm_resp_hdr *resp = (struct tpm_resp_hdr *)buf;
  97
  98     return be32_to_cpu(resp->len);
  99 }
 100
 101 /*
 102  * Write an error message in the given output buffer.
 103  */
 104 static void tpm_write_fatal_error_response(uint8_t *out, uint32_t out_len)
 105 {
 106     if (out_len >= sizeof(struct tpm_resp_hdr)) {
 107         struct tpm_resp_hdr *resp = (struct tpm_resp_hdr *)out;
 108
 109         resp->tag = cpu_to_be16(TPM_TAG_RSP_COMMAND);
 110         resp->len = cpu_to_be32(sizeof(struct tpm_resp_hdr));
 111         resp->errcode = cpu_to_be32(TPM_FAIL);
 112     }
 113 }
 114
 115 static int tpm_passthrough_unix_tx_bufs(TPMPassthruState *tpm_pt,
 116                                         const uint8_t *in, uint32_t in_len,
 117                                         uint8_t *out, uint32_t out_len)
 118 {
 119     int ret;
 120
 121     tpm_pt->tpm_op_canceled = false;
 122     tpm_pt->tpm_executing = true;
 123
 124     ret = tpm_passthrough_unix_write(tpm_pt->tpm_fd, in, in_len);
 125     if (ret != in_len) {
 126         if (!tpm_pt->tpm_op_canceled ||
 127             (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {
 128             error_report("tpm_passthrough: error while transmitting data "
 129                          "to TPM: %s (%i)\n",
 130                          strerror(errno), errno);
 131         }
 132         goto err_exit;
 133     }
 134
 135     tpm_pt->tpm_executing = false;
 136
 137     ret = tpm_passthrough_unix_read(tpm_pt->tpm_fd, out, out_len);
 138     if (ret < 0) {
 139         if (!tpm_pt->tpm_op_canceled ||
 140             (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {
 141             error_report("tpm_passthrough: error while reading data from "
 142                          "TPM: %s (%i)\n",
 143                          strerror(errno), errno);
 144         }
 145     } else if (ret < sizeof(struct tpm_resp_hdr) ||
 146                tpm_passthrough_get_size_from_buffer(out) != ret) {
 147         ret = -1;
 148         error_report("tpm_passthrough: received invalid response "
 149                      "packet from TPM\n");
 150     }
 151
 152 err_exit:
 153     if (ret < 0) {
 154         tpm_write_fatal_error_response(out, out_len);
 155     }
 156
 157     tpm_pt->tpm_executing = false;
 158
 159     return ret;
 160 }
 161
 162 static int tpm_passthrough_unix_transfer(TPMPassthruState *tpm_pt,
 163                                          const TPMLocality *locty_data)
 164 {
 165     return tpm_passthrough_unix_tx_bufs(tpm_pt,
 166                                         locty_data->w_buffer.buffer,
 167                                         locty_data->w_offset,
 168                                         locty_data->r_buffer.buffer,
 169                                         locty_data->r_buffer.size);
 170 }
 171
 172 static void tpm_passthrough_worker_thread(gpointer data,
 173                                           gpointer user_data)
 174 {
 175     TPMPassthruThreadParams *thr_parms = user_data;
 176     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(thr_parms->tb);
 177     TPMBackendCmd cmd = (TPMBackendCmd)data;
 178
 179     DPRINTF("tpm_passthrough: processing command type %d\n", cmd);
 180
 181     switch (cmd) {
 182     case TPM_BACKEND_CMD_PROCESS_CMD:
 183         tpm_passthrough_unix_transfer(tpm_pt,
 184                                       thr_parms->tpm_state->locty_data);
 185
 186         thr_parms->recv_data_callback(thr_parms->tpm_state,
 187                                       thr_parms->tpm_state->locty_number);
 188         break;
 189     case TPM_BACKEND_CMD_INIT:
 190     case TPM_BACKEND_CMD_END:
 191     case TPM_BACKEND_CMD_TPM_RESET:
 192         /* nothing to do */
 193         break;
 194     }
 195 }
 196
 197 /*
 198  * Start the TPM (thread). If it had been started before, then terminate
 199  * and start it again.
 200  */
 201 static int tpm_passthrough_startup_tpm(TPMBackend *tb)
 202 {
 203     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 204
 205     /* terminate a running TPM */
 206     tpm_backend_thread_end(&tpm_pt->tbt);
 207
 208     tpm_backend_thread_create(&tpm_pt->tbt,
 209                               tpm_passthrough_worker_thread,
 210                               &tpm_pt->tpm_thread_params);
 211
 212     return 0;
 213 }
 214
 215 static void tpm_passthrough_reset(TPMBackend *tb)
 216 {
 217     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 218
 219     DPRINTF("tpm_passthrough: CALL TO TPM_RESET!\n");
 220
 221     tpm_passthrough_cancel_cmd(tb);
 222
 223     tpm_backend_thread_end(&tpm_pt->tbt);
 224
 225     tpm_pt->had_startup_error = false;
 226 }
 227
 228 static int tpm_passthrough_init(TPMBackend *tb, TPMState *s,
 229                                 TPMRecvDataCB *recv_data_cb)
 230 {
 231     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 232
 233     tpm_pt->tpm_thread_params.tpm_state = s;
 234     tpm_pt->tpm_thread_params.recv_data_callback = recv_data_cb;
 235     tpm_pt->tpm_thread_params.tb = tb;
 236
 237     return 0;
 238 }
 239
 240 static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)
 241 {
 242     return false;
 243 }
 244
 245 static bool tpm_passthrough_get_startup_error(TPMBackend *tb)
 246 {
 247     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 248
 249     return tpm_pt->had_startup_error;
 250 }
 251
 252 static size_t tpm_passthrough_realloc_buffer(TPMSizedBuffer *sb)
 253 {
 254     size_t wanted_size = 4096; /* Linux tpm.c buffer size */
 255
 256     if (sb->size != wanted_size) {
 257         sb->buffer = g_realloc(sb->buffer, wanted_size);
 258         sb->size = wanted_size;
 259     }
 260     return sb->size;
 261 }
 262
 263 static void tpm_passthrough_deliver_request(TPMBackend *tb)
 264 {
 265     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 266
 267     tpm_backend_thread_deliver_request(&tpm_pt->tbt);
 268 }
 269
 270 static void tpm_passthrough_cancel_cmd(TPMBackend *tb)
 271 {
 272     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 273     int n;
 274
 275     /*
 276      * As of Linux 3.7 the tpm_tis driver does not properly cancel
 277      * commands on all TPM manufacturers' TPMs.
 278      * Only cancel if we're busy so we don't cancel someone else's
 279      * command, e.g., a command executed on the host.
 280      */
 281     if (tpm_pt->tpm_executing) {
 282         if (tpm_pt->cancel_fd >= 0) {
 283             n = write(tpm_pt->cancel_fd, "-", 1);
 284             if (n != 1) {
 285                 error_report("Canceling TPM command failed: %s\n",
 286                              strerror(errno));
 287             } else {
 288                 tpm_pt->tpm_op_canceled = true;
 289             }
 290         } else {
 291             error_report("Cannot cancel TPM command due to missing "
 292                          "TPM sysfs cancel entry");
 293         }
 294     }
 295 }
 296
 297 static const char *tpm_passthrough_create_desc(void)
 298 {
 299     return "Passthrough TPM backend driver";
 300 }
 301
 302 /*
 303  * A basic test of a TPM device. We expect a well formatted response header
 304  * (error response is fine) within one second.
 305  */
 306 static int tpm_passthrough_test_tpmdev(int fd)
 307 {
 308     struct tpm_req_hdr req = {
 309         .tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
 310         .len = cpu_to_be32(sizeof(req)),
 311         .ordinal = cpu_to_be32(TPM_ORD_GetTicks),
 312     };
 313     struct tpm_resp_hdr *resp;
 314     fd_set readfds;
 315     int n;
 316     struct timeval tv = {
 317         .tv_sec = 1,
 318         .tv_usec = 0,
 319     };
 320     unsigned char buf[1024];
 321
 322     n = write(fd, &req, sizeof(req));
 323     if (n < 0) {
 324         return errno;
 325     }
 326     if (n != sizeof(req)) {
 327         return EFAULT;
 328     }
 329
 330     FD_ZERO(&readfds);
 331     FD_SET(fd, &readfds);
 332
 333     /* wait for a second */
 334     n = select(fd + 1, &readfds, NULL, NULL, &tv);
 335     if (n != 1) {
 336         return errno;
 337     }
 338
 339     n = read(fd, &buf, sizeof(buf));
 340     if (n < sizeof(struct tpm_resp_hdr)) {
 341         return EFAULT;
 342     }
 343
 344     resp = (struct tpm_resp_hdr *)buf;
 345     /* check the header */
 346     if (be16_to_cpu(resp->tag) != TPM_TAG_RSP_COMMAND ||
 347         be32_to_cpu(resp->len) != n) {
 348         return EBADMSG;
 349     }
 350
 351     return 0;
 352 }
 353
 354 /*
 355  * Check whether the given base path, e.g.,  /sys/class/misc/tpm0/device,
 356  * is the sysfs directory of a TPM. A TPM sysfs directory should be uniquely
 357  * recognizable by the file entries 'pcrs' and 'cancel'.
 358  * Upon success 'true' is returned and the basebath buffer has '/cancel'
 359  * appended.
 360  */
 361 static bool tpm_passthrough_check_sysfs_cancel(char *basepath, size_t bufsz)
 362 {
 363     char path[PATH_MAX];
 364     struct stat statbuf;
 365
 366     snprintf(path, sizeof(path), "%s/pcrs", basepath);
 367     if (stat(path, &statbuf) == -1 || !S_ISREG(statbuf.st_mode)) {
 368         return false;
 369     }
 370
 371     snprintf(path, sizeof(path), "%s/cancel", basepath);
 372     if (stat(path, &statbuf) == -1 || !S_ISREG(statbuf.st_mode)) {
 373         return false;
 374     }
 375
 376     strncpy(basepath, path, bufsz);
 377
 378     return true;
 379 }
 380
 381 /*
 382  * Unless path or file descriptor set has been provided by user,
 383  * determine the sysfs cancel file following kernel documentation
 384  * in Documentation/ABI/stable/sysfs-class-tpm.
 385  */
 386 static int tpm_passthrough_open_sysfs_cancel(TPMBackend *tb)
 387 {
 388     int fd = -1;
 389     unsigned int idx;
 390     DIR *pnp_dir;
 391     char path[PATH_MAX];
 392     struct dirent entry, *result;
 393     int len;
 394
 395     if (tb->cancel_path) {
 396         fd = qemu_open(tb->cancel_path, O_WRONLY);
 397         if (fd < 0) {
 398             error_report("Could not open TPM cancel path : %s",
 399                          strerror(errno));
 400         }
 401         return fd;
 402     }
 403
 404     snprintf(path, sizeof(path), "/sys/class/misc");
 405     pnp_dir = opendir(path);
 406     if (pnp_dir != NULL) {
 407         while (readdir_r(pnp_dir, &entry, &result) == 0 &&
 408                result != NULL) {
 409             /*
 410              * only allow /sys/class/misc/tpm%u type of paths
 411              */
 412             if (sscanf(entry.d_name, "tpm%u%n", &idx, &len) < 1 ||
 413                 len <= strlen("tpm") ||
 414                 len != strlen(entry.d_name)) {
 415                 continue;
 416             }
 417
 418             snprintf(path, sizeof(path), "/sys/class/misc/%s/device",
 419                      entry.d_name);
 420             if (!tpm_passthrough_check_sysfs_cancel(path, sizeof(path))) {
 421                 continue;
 422             }
 423
 424             fd = qemu_open(path, O_WRONLY);
 425             break;
 426         }
 427         closedir(pnp_dir);
 428     }
 429
 430     if (fd >= 0) {
 431         tb->cancel_path = g_strdup(path);
 432     }
 433
 434     return fd;
 435 }
 436
 437 static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)
 438 {
 439     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 440     const char *value;
 441
 442     value = qemu_opt_get(opts, "cancel-path");
 443     if (value) {
 444         tb->cancel_path = g_strdup(value);
 445     }
 446
 447     value = qemu_opt_get(opts, "path");
 448     if (!value) {
 449         value = TPM_PASSTHROUGH_DEFAULT_DEVICE;
 450     }
 451
 452     tpm_pt->tpm_dev = g_strdup(value);
 453
 454     tb->path = g_strdup(tpm_pt->tpm_dev);
 455
 456     tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
 457     if (tpm_pt->tpm_fd < 0) {
 458         error_report("Cannot access TPM device using '%s': %s\n",
 459                      tpm_pt->tpm_dev, strerror(errno));
 460         goto err_free_parameters;
 461     }
 462
 463     if (tpm_passthrough_test_tpmdev(tpm_pt->tpm_fd)) {
 464         error_report("'%s' is not a TPM device.\n",
 465                      tpm_pt->tpm_dev);
 466         goto err_close_tpmdev;
 467     }
 468
 469     return 0;
 470
 471  err_close_tpmdev:
 472     qemu_close(tpm_pt->tpm_fd);
 473     tpm_pt->tpm_fd = -1;
 474
 475  err_free_parameters:
 476     g_free(tb->path);
 477     tb->path = NULL;
 478
 479     g_free(tpm_pt->tpm_dev);
 480     tpm_pt->tpm_dev = NULL;
 481
 482     return 1;
 483 }
 484
 485 static TPMBackend *tpm_passthrough_create(QemuOpts *opts, const char *id)
 486 {
 487     Object *obj = object_new(TYPE_TPM_PASSTHROUGH);
 488     TPMBackend *tb = TPM_BACKEND(obj);
 489     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 490
 491     tb->id = g_strdup(id);
 492     /* let frontend set the fe_model to proper value */
 493     tb->fe_model = -1;
 494
 495     tb->ops = &tpm_passthrough_driver;
 496
 497     if (tpm_passthrough_handle_device_opts(opts, tb)) {
 498         goto err_exit;
 499     }
 500
 501     tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tb);
 502     if (tpm_pt->cancel_fd < 0) {
 503         goto err_exit;
 504     }
 505
 506     return tb;
 507
 508 err_exit:
 509     g_free(tb->id);
 510
 511     return NULL;
 512 }
 513
 514 static void tpm_passthrough_destroy(TPMBackend *tb)
 515 {
 516     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 517
 518     tpm_passthrough_cancel_cmd(tb);
 519
 520     tpm_backend_thread_end(&tpm_pt->tbt);
 521
 522     qemu_close(tpm_pt->tpm_fd);
 523     qemu_close(tpm_pt->cancel_fd);
 524
 525     g_free(tb->id);
 526     g_free(tb->path);
 527     g_free(tb->cancel_path);
 528     g_free(tpm_pt->tpm_dev);
 529 }
 530
 531 static const TPMDriverOps tpm_passthrough_driver = {
 532     .type                     = TPM_TYPE_PASSTHROUGH,
 533     .desc                     = tpm_passthrough_create_desc,
 534     .create                   = tpm_passthrough_create,
 535     .destroy                  = tpm_passthrough_destroy,
 536     .init                     = tpm_passthrough_init,
 537     .startup_tpm              = tpm_passthrough_startup_tpm,
 538     .realloc_buffer           = tpm_passthrough_realloc_buffer,
 539     .reset                    = tpm_passthrough_reset,
 540     .had_startup_error        = tpm_passthrough_get_startup_error,
 541     .deliver_request          = tpm_passthrough_deliver_request,
 542     .cancel_cmd               = tpm_passthrough_cancel_cmd,
 543     .get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag,
 544 };
 545
 546 static void tpm_passthrough_inst_init(Object *obj)
 547 {
 548 }
 549
 550 static void tpm_passthrough_inst_finalize(Object *obj)
 551 {
 552 }
 553
 554 static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
 555 {
 556     TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);
 557
 558     tbc->ops = &tpm_passthrough_driver;
 559 }
 560
 561 static const TypeInfo tpm_passthrough_info = {
 562     .name = TYPE_TPM_PASSTHROUGH,
 563     .parent = TYPE_TPM_BACKEND,
 564     .instance_size = sizeof(TPMPassthruState),
 565     .class_init = tpm_passthrough_class_init,
 566     .instance_init = tpm_passthrough_inst_init,
 567     .instance_finalize = tpm_passthrough_inst_finalize,
 568 };
 569
 570 static void tpm_passthrough_register(void)
 571 {
 572     type_register_static(&tpm_passthrough_info);
 573     tpm_register_driver(&tpm_passthrough_driver);
 574 }
 575
 576 type_init(tpm_passthrough_register)