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 "sysemu/tpm_backend.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 0
  38
  39 #define DPRINTF(fmt, ...) do { \
  40     if (DEBUG_TPM) { \
  41         fprintf(stderr, fmt, ## __VA_ARGS__); \
  42     } \
  43 } while (0);
  44
  45 #define TYPE_TPM_PASSTHROUGH "tpm-passthrough"
  46 #define TPM_PASSTHROUGH(obj) \
  47     OBJECT_CHECK(TPMPassthruState, (obj), TYPE_TPM_PASSTHROUGH)
  48
  49 static const TPMDriverOps tpm_passthrough_driver;
  50
  51 /* data structures */
  52 typedef struct TPMPassthruThreadParams {
  53     TPMState *tpm_state;
  54
  55     TPMRecvDataCB *recv_data_callback;
  56     TPMBackend *tb;
  57 } TPMPassthruThreadParams;
  58
  59 struct TPMPassthruState {
  60     TPMBackend parent;
  61
  62     TPMBackendThread tbt;
  63
  64     TPMPassthruThreadParams tpm_thread_params;
  65
  66     char *tpm_dev;
  67     int tpm_fd;
  68     bool tpm_executing;
  69     bool tpm_op_canceled;
  70     int cancel_fd;
  71     bool had_startup_error;
  72 };
  73
  74 typedef struct TPMPassthruState TPMPassthruState;
  75
  76 #define TPM_PASSTHROUGH_DEFAULT_DEVICE "/dev/tpm0"
  77
  78 /* functions */
  79
  80 static void tpm_passthrough_cancel_cmd(TPMBackend *tb);
  81
  82 static int tpm_passthrough_unix_write(int fd, const uint8_t *buf, uint32_t len)
  83 {
  84     return send_all(fd, buf, len);
  85 }
  86
  87 static int tpm_passthrough_unix_read(int fd, uint8_t *buf, uint32_t len)
  88 {
  89     return recv_all(fd, buf, len, true);
  90 }
  91
  92 static uint32_t tpm_passthrough_get_size_from_buffer(const uint8_t *buf)
  93 {
  94     struct tpm_resp_hdr *resp = (struct tpm_resp_hdr *)buf;
  95
  96     return be32_to_cpu(resp->len);
  97 }
  98
  99 /*
 100  * Write an error message in the given output buffer.
 101  */
 102 static void tpm_write_fatal_error_response(uint8_t *out, uint32_t out_len)
 103 {
 104     if (out_len >= sizeof(struct tpm_resp_hdr)) {
 105         struct tpm_resp_hdr *resp = (struct tpm_resp_hdr *)out;
 106
 107         resp->tag = cpu_to_be16(TPM_TAG_RSP_COMMAND);
 108         resp->len = cpu_to_be32(sizeof(struct tpm_resp_hdr));
 109         resp->errcode = cpu_to_be32(TPM_FAIL);
 110     }
 111 }
 112
 113 static bool tpm_passthrough_is_selftest(const uint8_t *in, uint32_t in_len)
 114 {
 115     struct tpm_req_hdr *hdr = (struct tpm_req_hdr *)in;
 116
 117     if (in_len >= sizeof(*hdr)) {
 118         return (be32_to_cpu(hdr->ordinal) == TPM_ORD_ContinueSelfTest);
 119     }
 120
 121     return false;
 122 }
 123
 124 static int tpm_passthrough_unix_tx_bufs(TPMPassthruState *tpm_pt,
 125                                         const uint8_t *in, uint32_t in_len,
 126                                         uint8_t *out, uint32_t out_len,
 127                                         bool *selftest_done)
 128 {
 129     int ret;
 130     bool is_selftest;
 131     const struct tpm_resp_hdr *hdr;
 132
 133     tpm_pt->tpm_op_canceled = false;
 134     tpm_pt->tpm_executing = true;
 135     *selftest_done = false;
 136
 137     is_selftest = tpm_passthrough_is_selftest(in, in_len);
 138
 139     ret = tpm_passthrough_unix_write(tpm_pt->tpm_fd, in, in_len);
 140     if (ret != in_len) {
 141         if (!tpm_pt->tpm_op_canceled ||
 142             (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {
 143             error_report("tpm_passthrough: error while transmitting data "
 144                          "to TPM: %s (%i)",
 145                          strerror(errno), errno);
 146         }
 147         goto err_exit;
 148     }
 149
 150     tpm_pt->tpm_executing = false;
 151
 152     ret = tpm_passthrough_unix_read(tpm_pt->tpm_fd, out, out_len);
 153     if (ret < 0) {
 154         if (!tpm_pt->tpm_op_canceled ||
 155             (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {
 156             error_report("tpm_passthrough: error while reading data from "
 157                          "TPM: %s (%i)",
 158                          strerror(errno), errno);
 159         }
 160     } else if (ret < sizeof(struct tpm_resp_hdr) ||
 161                tpm_passthrough_get_size_from_buffer(out) != ret) {
 162         ret = -1;
 163         error_report("tpm_passthrough: received invalid response "
 164                      "packet from TPM");
 165     }
 166
 167     if (is_selftest && (ret >= sizeof(struct tpm_resp_hdr))) {
 168         hdr = (struct tpm_resp_hdr *)out;
 169         *selftest_done = (be32_to_cpu(hdr->errcode) == 0);
 170     }
 171
 172 err_exit:
 173     if (ret < 0) {
 174         tpm_write_fatal_error_response(out, out_len);
 175     }
 176
 177     tpm_pt->tpm_executing = false;
 178
 179     return ret;
 180 }
 181
 182 static int tpm_passthrough_unix_transfer(TPMPassthruState *tpm_pt,
 183                                          const TPMLocality *locty_data,
 184                                          bool *selftest_done)
 185 {
 186     return tpm_passthrough_unix_tx_bufs(tpm_pt,
 187                                         locty_data->w_buffer.buffer,
 188                                         locty_data->w_offset,
 189                                         locty_data->r_buffer.buffer,
 190                                         locty_data->r_buffer.size,
 191                                         selftest_done);
 192 }
 193
 194 static void tpm_passthrough_worker_thread(gpointer data,
 195                                           gpointer user_data)
 196 {
 197     TPMPassthruThreadParams *thr_parms = user_data;
 198     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(thr_parms->tb);
 199     TPMBackendCmd cmd = (TPMBackendCmd)data;
 200     bool selftest_done = false;
 201
 202     DPRINTF("tpm_passthrough: processing command type %d\n", cmd);
 203
 204     switch (cmd) {
 205     case TPM_BACKEND_CMD_PROCESS_CMD:
 206         tpm_passthrough_unix_transfer(tpm_pt,
 207                                       thr_parms->tpm_state->locty_data,
 208                                       &selftest_done);
 209
 210         thr_parms->recv_data_callback(thr_parms->tpm_state,
 211                                       thr_parms->tpm_state->locty_number,
 212                                       selftest_done);
 213         break;
 214     case TPM_BACKEND_CMD_INIT:
 215     case TPM_BACKEND_CMD_END:
 216     case TPM_BACKEND_CMD_TPM_RESET:
 217         /* nothing to do */
 218         break;
 219     }
 220 }
 221
 222 /*
 223  * Start the TPM (thread). If it had been started before, then terminate
 224  * and start it again.
 225  */
 226 static int tpm_passthrough_startup_tpm(TPMBackend *tb)
 227 {
 228     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 229
 230     /* terminate a running TPM */
 231     tpm_backend_thread_end(&tpm_pt->tbt);
 232
 233     tpm_backend_thread_create(&tpm_pt->tbt,
 234                               tpm_passthrough_worker_thread,
 235                               &tpm_pt->tpm_thread_params);
 236
 237     return 0;
 238 }
 239
 240 static void tpm_passthrough_reset(TPMBackend *tb)
 241 {
 242     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 243
 244     DPRINTF("tpm_passthrough: CALL TO TPM_RESET!\n");
 245
 246     tpm_passthrough_cancel_cmd(tb);
 247
 248     tpm_backend_thread_end(&tpm_pt->tbt);
 249
 250     tpm_pt->had_startup_error = false;
 251 }
 252
 253 static int tpm_passthrough_init(TPMBackend *tb, TPMState *s,
 254                                 TPMRecvDataCB *recv_data_cb)
 255 {
 256     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 257
 258     tpm_pt->tpm_thread_params.tpm_state = s;
 259     tpm_pt->tpm_thread_params.recv_data_callback = recv_data_cb;
 260     tpm_pt->tpm_thread_params.tb = tb;
 261
 262     return 0;
 263 }
 264
 265 static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)
 266 {
 267     return false;
 268 }
 269
 270 static int tpm_passthrough_reset_tpm_established_flag(TPMBackend *tb,
 271                                                       uint8_t locty)
 272 {
 273     /* only a TPM 2.0 will support this */
 274     return 0;
 275 }
 276
 277 static bool tpm_passthrough_get_startup_error(TPMBackend *tb)
 278 {
 279     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 280
 281     return tpm_pt->had_startup_error;
 282 }
 283
 284 static size_t tpm_passthrough_realloc_buffer(TPMSizedBuffer *sb)
 285 {
 286     size_t wanted_size = 4096; /* Linux tpm.c buffer size */
 287
 288     if (sb->size != wanted_size) {
 289         sb->buffer = g_realloc(sb->buffer, wanted_size);
 290         sb->size = wanted_size;
 291     }
 292     return sb->size;
 293 }
 294
 295 static void tpm_passthrough_deliver_request(TPMBackend *tb)
 296 {
 297     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 298
 299     tpm_backend_thread_deliver_request(&tpm_pt->tbt);
 300 }
 301
 302 static void tpm_passthrough_cancel_cmd(TPMBackend *tb)
 303 {
 304     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 305     int n;
 306
 307     /*
 308      * As of Linux 3.7 the tpm_tis driver does not properly cancel
 309      * commands on all TPM manufacturers' TPMs.
 310      * Only cancel if we're busy so we don't cancel someone else's
 311      * command, e.g., a command executed on the host.
 312      */
 313     if (tpm_pt->tpm_executing) {
 314         if (tpm_pt->cancel_fd >= 0) {
 315             n = write(tpm_pt->cancel_fd, "-", 1);
 316             if (n != 1) {
 317                 error_report("Canceling TPM command failed: %s",
 318                              strerror(errno));
 319             } else {
 320                 tpm_pt->tpm_op_canceled = true;
 321             }
 322         } else {
 323             error_report("Cannot cancel TPM command due to missing "
 324                          "TPM sysfs cancel entry");
 325         }
 326     }
 327 }
 328
 329 static const char *tpm_passthrough_create_desc(void)
 330 {
 331     return "Passthrough TPM backend driver";
 332 }
 333
 334 static TPMVersion tpm_passthrough_get_tpm_version(TPMBackend *tb)
 335 {
 336     return TPM_VERSION_1_2;
 337 }
 338
 339 /*
 340  * A basic test of a TPM device. We expect a well formatted response header
 341  * (error response is fine) within one second.
 342  */
 343 static int tpm_passthrough_test_tpmdev(int fd)
 344 {
 345     struct tpm_req_hdr req = {
 346         .tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
 347         .len = cpu_to_be32(sizeof(req)),
 348         .ordinal = cpu_to_be32(TPM_ORD_GetTicks),
 349     };
 350     struct tpm_resp_hdr *resp;
 351     fd_set readfds;
 352     int n;
 353     struct timeval tv = {
 354         .tv_sec = 1,
 355         .tv_usec = 0,
 356     };
 357     unsigned char buf[1024];
 358
 359     n = write(fd, &req, sizeof(req));
 360     if (n < 0) {
 361         return errno;
 362     }
 363     if (n != sizeof(req)) {
 364         return EFAULT;
 365     }
 366
 367     FD_ZERO(&readfds);
 368     FD_SET(fd, &readfds);
 369
 370     /* wait for a second */
 371     n = select(fd + 1, &readfds, NULL, NULL, &tv);
 372     if (n != 1) {
 373         return errno;
 374     }
 375
 376     n = read(fd, &buf, sizeof(buf));
 377     if (n < sizeof(struct tpm_resp_hdr)) {
 378         return EFAULT;
 379     }
 380
 381     resp = (struct tpm_resp_hdr *)buf;
 382     /* check the header */
 383     if (be16_to_cpu(resp->tag) != TPM_TAG_RSP_COMMAND ||
 384         be32_to_cpu(resp->len) != n) {
 385         return EBADMSG;
 386     }
 387
 388     return 0;
 389 }
 390
 391 /*
 392  * Unless path or file descriptor set has been provided by user,
 393  * determine the sysfs cancel file following kernel documentation
 394  * in Documentation/ABI/stable/sysfs-class-tpm.
 395  * From /dev/tpm0 create /sys/class/misc/tpm0/device/cancel
 396  */
 397 static int tpm_passthrough_open_sysfs_cancel(TPMBackend *tb)
 398 {
 399     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 400     int fd = -1;
 401     char *dev;
 402     char path[PATH_MAX];
 403
 404     if (tb->cancel_path) {
 405         fd = qemu_open(tb->cancel_path, O_WRONLY);
 406         if (fd < 0) {
 407             error_report("Could not open TPM cancel path : %s",
 408                          strerror(errno));
 409         }
 410         return fd;
 411     }
 412
 413     dev = strrchr(tpm_pt->tpm_dev, '/');
 414     if (dev) {
 415         dev++;
 416         if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
 417                      dev) < sizeof(path)) {
 418             fd = qemu_open(path, O_WRONLY);
 419             if (fd >= 0) {
 420                 tb->cancel_path = g_strdup(path);
 421             } else {
 422                 error_report("tpm_passthrough: Could not open TPM cancel "
 423                              "path %s : %s", path, strerror(errno));
 424             }
 425         }
 426     } else {
 427        error_report("tpm_passthrough: Bad TPM device path %s",
 428                     tpm_pt->tpm_dev);
 429     }
 430
 431     return fd;
 432 }
 433
 434 static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)
 435 {
 436     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 437     const char *value;
 438
 439     value = qemu_opt_get(opts, "cancel-path");
 440     tb->cancel_path = g_strdup(value);
 441
 442     value = qemu_opt_get(opts, "path");
 443     if (!value) {
 444         value = TPM_PASSTHROUGH_DEFAULT_DEVICE;
 445     }
 446
 447     tpm_pt->tpm_dev = g_strdup(value);
 448
 449     tb->path = g_strdup(tpm_pt->tpm_dev);
 450
 451     tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
 452     if (tpm_pt->tpm_fd < 0) {
 453         error_report("Cannot access TPM device using '%s': %s",
 454                      tpm_pt->tpm_dev, strerror(errno));
 455         goto err_free_parameters;
 456     }
 457
 458     if (tpm_passthrough_test_tpmdev(tpm_pt->tpm_fd)) {
 459         error_report("'%s' is not a TPM device.",
 460                      tpm_pt->tpm_dev);
 461         goto err_close_tpmdev;
 462     }
 463
 464     return 0;
 465
 466  err_close_tpmdev:
 467     qemu_close(tpm_pt->tpm_fd);
 468     tpm_pt->tpm_fd = -1;
 469
 470  err_free_parameters:
 471     g_free(tb->path);
 472     tb->path = NULL;
 473
 474     g_free(tpm_pt->tpm_dev);
 475     tpm_pt->tpm_dev = NULL;
 476
 477     return 1;
 478 }
 479
 480 static TPMBackend *tpm_passthrough_create(QemuOpts *opts, const char *id)
 481 {
 482     Object *obj = object_new(TYPE_TPM_PASSTHROUGH);
 483     TPMBackend *tb = TPM_BACKEND(obj);
 484     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 485
 486     tb->id = g_strdup(id);
 487     /* let frontend set the fe_model to proper value */
 488     tb->fe_model = -1;
 489
 490     tb->ops = &tpm_passthrough_driver;
 491
 492     if (tpm_passthrough_handle_device_opts(opts, tb)) {
 493         goto err_exit;
 494     }
 495
 496     tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tb);
 497     if (tpm_pt->cancel_fd < 0) {
 498         goto err_exit;
 499     }
 500
 501     return tb;
 502
 503 err_exit:
 504     g_free(tb->id);
 505
 506     return NULL;
 507 }
 508
 509 static void tpm_passthrough_destroy(TPMBackend *tb)
 510 {
 511     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 512
 513     tpm_passthrough_cancel_cmd(tb);
 514
 515     tpm_backend_thread_end(&tpm_pt->tbt);
 516
 517     qemu_close(tpm_pt->tpm_fd);
 518     qemu_close(tpm_pt->cancel_fd);
 519
 520     g_free(tb->id);
 521     g_free(tb->path);
 522     g_free(tb->cancel_path);
 523     g_free(tpm_pt->tpm_dev);
 524 }
 525
 526 static const QemuOptDesc tpm_passthrough_cmdline_opts[] = {
 527     TPM_STANDARD_CMDLINE_OPTS,
 528     {
 529         .name = "cancel-path",
 530         .type = QEMU_OPT_STRING,
 531         .help = "Sysfs file entry for canceling TPM commands",
 532     },
 533     {
 534         .name = "path",
 535         .type = QEMU_OPT_STRING,
 536         .help = "Path to TPM device on the host",
 537     },
 538     { /* end of list */ },
 539 };
 540
 541 static const TPMDriverOps tpm_passthrough_driver = {
 542     .type                     = TPM_TYPE_PASSTHROUGH,
 543     .opts                     = tpm_passthrough_cmdline_opts,
 544     .desc                     = tpm_passthrough_create_desc,
 545     .create                   = tpm_passthrough_create,
 546     .destroy                  = tpm_passthrough_destroy,
 547     .init                     = tpm_passthrough_init,
 548     .startup_tpm              = tpm_passthrough_startup_tpm,
 549     .realloc_buffer           = tpm_passthrough_realloc_buffer,
 550     .reset                    = tpm_passthrough_reset,
 551     .had_startup_error        = tpm_passthrough_get_startup_error,
 552     .deliver_request          = tpm_passthrough_deliver_request,
 553     .cancel_cmd               = tpm_passthrough_cancel_cmd,
 554     .get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag,
 555     .reset_tpm_established_flag = tpm_passthrough_reset_tpm_established_flag,
 556     .get_tpm_version          = tpm_passthrough_get_tpm_version,
 557 };
 558
 559 static void tpm_passthrough_inst_init(Object *obj)
 560 {
 561 }
 562
 563 static void tpm_passthrough_inst_finalize(Object *obj)
 564 {
 565 }
 566
 567 static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
 568 {
 569     TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);
 570
 571     tbc->ops = &tpm_passthrough_driver;
 572 }
 573
 574 static const TypeInfo tpm_passthrough_info = {
 575     .name = TYPE_TPM_PASSTHROUGH,
 576     .parent = TYPE_TPM_BACKEND,
 577     .instance_size = sizeof(TPMPassthruState),
 578     .class_init = tpm_passthrough_class_init,
 579     .instance_init = tpm_passthrough_inst_init,
 580     .instance_finalize = tpm_passthrough_inst_finalize,
 581 };
 582
 583 static void tpm_passthrough_register(void)
 584 {
 585     type_register_static(&tpm_passthrough_info);
 586     tpm_register_driver(&tpm_passthrough_driver);
 587 }
 588
 589 type_init(tpm_passthrough_register)