hw/tpm/tpm_passthrough.c

   1 /*
   2  *  passthrough TPM driver
   3  *
   4  *  Copyright (c) 2010 - 2013 IBM Corporation
   5  *  Authors:
   6  *    Stefan Berger <[email protected]>
   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 */
  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 bool tpm_passthrough_is_selftest(const uint8_t *in, uint32_t in_len)
 116 {
 117     struct tpm_req_hdr *hdr = (struct tpm_req_hdr *)in;
 118
 119     if (in_len >= sizeof(*hdr)) {
 120         return (be32_to_cpu(hdr->ordinal) == TPM_ORD_ContinueSelfTest);
 121     }
 122
 123     return false;
 124 }
 125
 126 static int tpm_passthrough_unix_tx_bufs(TPMPassthruState *tpm_pt,
 127                                         const uint8_t *in, uint32_t in_len,
 128                                         uint8_t *out, uint32_t out_len,
 129                                         bool *selftest_done)
 130 {
 131     int ret;
 132     bool is_selftest;
 133     const struct tpm_resp_hdr *hdr;
 134
 135     tpm_pt->tpm_op_canceled = false;
 136     tpm_pt->tpm_executing = true;
 137     *selftest_done = false;
 138
 139     is_selftest = tpm_passthrough_is_selftest(in, in_len);
 140
 141     ret = tpm_passthrough_unix_write(tpm_pt->tpm_fd, in, in_len);
 142     if (ret != in_len) {
 143         if (!tpm_pt->tpm_op_canceled ||
 144             (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {
 145             error_report("tpm_passthrough: error while transmitting data "
 146                          "to TPM: %s (%i)",
 147                          strerror(errno), errno);
 148         }
 149         goto err_exit;
 150     }
 151
 152     tpm_pt->tpm_executing = false;
 153
 154     ret = tpm_passthrough_unix_read(tpm_pt->tpm_fd, out, out_len);
 155     if (ret < 0) {
 156         if (!tpm_pt->tpm_op_canceled ||
 157             (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {
 158             error_report("tpm_passthrough: error while reading data from "
 159                          "TPM: %s (%i)",
 160                          strerror(errno), errno);
 161         }
 162     } else if (ret < sizeof(struct tpm_resp_hdr) ||
 163                tpm_passthrough_get_size_from_buffer(out) != ret) {
 164         ret = -1;
 165         error_report("tpm_passthrough: received invalid response "
 166                      "packet from TPM");
 167     }
 168
 169     if (is_selftest && (ret >= sizeof(struct tpm_resp_hdr))) {
 170         hdr = (struct tpm_resp_hdr *)out;
 171         *selftest_done = (be32_to_cpu(hdr->errcode) == 0);
 172     }
 173
 174 err_exit:
 175     if (ret < 0) {
 176         tpm_write_fatal_error_response(out, out_len);
 177     }
 178
 179     tpm_pt->tpm_executing = false;
 180
 181     return ret;
 182 }
 183
 184 static int tpm_passthrough_unix_transfer(TPMPassthruState *tpm_pt,
 185                                          const TPMLocality *locty_data,
 186                                          bool *selftest_done)
 187 {
 188     return tpm_passthrough_unix_tx_bufs(tpm_pt,
 189                                         locty_data->w_buffer.buffer,
 190                                         locty_data->w_offset,
 191                                         locty_data->r_buffer.buffer,
 192                                         locty_data->r_buffer.size,
 193                                         selftest_done);
 194 }
 195
 196 static void tpm_passthrough_worker_thread(gpointer data,
 197                                           gpointer user_data)
 198 {
 199     TPMPassthruThreadParams *thr_parms = user_data;
 200     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(thr_parms->tb);
 201     TPMBackendCmd cmd = (TPMBackendCmd)data;
 202     bool selftest_done = false;
 203
 204     DPRINTF("tpm_passthrough: processing command type %d\n", cmd);
 205
 206     switch (cmd) {
 207     case TPM_BACKEND_CMD_PROCESS_CMD:
 208         tpm_passthrough_unix_transfer(tpm_pt,
 209                                       thr_parms->tpm_state->locty_data,
 210                                       &selftest_done);
 211
 212         thr_parms->recv_data_callback(thr_parms->tpm_state,
 213                                       thr_parms->tpm_state->locty_number,
 214                                       selftest_done);
 215         break;
 216     case TPM_BACKEND_CMD_INIT:
 217     case TPM_BACKEND_CMD_END:
 218     case TPM_BACKEND_CMD_TPM_RESET:
 219         /* nothing to do */
 220         break;
 221     }
 222 }
 223
 224 /*
 225  * Start the TPM (thread). If it had been started before, then terminate
 226  * and start it again.
 227  */
 228 static int tpm_passthrough_startup_tpm(TPMBackend *tb)
 229 {
 230     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 231
 232     /* terminate a running TPM */
 233     tpm_backend_thread_end(&tpm_pt->tbt);
 234
 235     tpm_backend_thread_create(&tpm_pt->tbt,
 236                               tpm_passthrough_worker_thread,
 237                               &tpm_pt->tpm_thread_params);
 238
 239     return 0;
 240 }
 241
 242 static void tpm_passthrough_reset(TPMBackend *tb)
 243 {
 244     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 245
 246     DPRINTF("tpm_passthrough: CALL TO TPM_RESET!\n");
 247
 248     tpm_passthrough_cancel_cmd(tb);
 249
 250     tpm_backend_thread_end(&tpm_pt->tbt);
 251
 252     tpm_pt->had_startup_error = false;
 253 }
 254
 255 static int tpm_passthrough_init(TPMBackend *tb, TPMState *s,
 256                                 TPMRecvDataCB *recv_data_cb)
 257 {
 258     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 259
 260     tpm_pt->tpm_thread_params.tpm_state = s;
 261     tpm_pt->tpm_thread_params.recv_data_callback = recv_data_cb;
 262     tpm_pt->tpm_thread_params.tb = tb;
 263
 264     return 0;
 265 }
 266
 267 static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)
 268 {
 269     return false;
 270 }
 271
 272 static bool tpm_passthrough_get_startup_error(TPMBackend *tb)
 273 {
 274     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 275
 276     return tpm_pt->had_startup_error;
 277 }
 278
 279 static size_t tpm_passthrough_realloc_buffer(TPMSizedBuffer *sb)
 280 {
 281     size_t wanted_size = 4096; /* Linux tpm.c buffer size */
 282
 283     if (sb->size != wanted_size) {
 284         sb->buffer = g_realloc(sb->buffer, wanted_size);
 285         sb->size = wanted_size;
 286     }
 287     return sb->size;
 288 }
 289
 290 static void tpm_passthrough_deliver_request(TPMBackend *tb)
 291 {
 292     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 293
 294     tpm_backend_thread_deliver_request(&tpm_pt->tbt);
 295 }
 296
 297 static void tpm_passthrough_cancel_cmd(TPMBackend *tb)
 298 {
 299     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 300     int n;
 301
 302     /*
 303      * As of Linux 3.7 the tpm_tis driver does not properly cancel
 304      * commands on all TPM manufacturers' TPMs.
 305      * Only cancel if we're busy so we don't cancel someone else's
 306      * command, e.g., a command executed on the host.
 307      */
 308     if (tpm_pt->tpm_executing) {
 309         if (tpm_pt->cancel_fd >= 0) {
 310             n = write(tpm_pt->cancel_fd, "-", 1);
 311             if (n != 1) {
 312                 error_report("Canceling TPM command failed: %s",
 313                              strerror(errno));
 314             } else {
 315                 tpm_pt->tpm_op_canceled = true;
 316             }
 317         } else {
 318             error_report("Cannot cancel TPM command due to missing "
 319                          "TPM sysfs cancel entry");
 320         }
 321     }
 322 }
 323
 324 static const char *tpm_passthrough_create_desc(void)
 325 {
 326     return "Passthrough TPM backend driver";
 327 }
 328
 329 /*
 330  * A basic test of a TPM device. We expect a well formatted response header
 331  * (error response is fine) within one second.
 332  */
 333 static int tpm_passthrough_test_tpmdev(int fd)
 334 {
 335     struct tpm_req_hdr req = {
 336         .tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
 337         .len = cpu_to_be32(sizeof(req)),
 338         .ordinal = cpu_to_be32(TPM_ORD_GetTicks),
 339     };
 340     struct tpm_resp_hdr *resp;
 341     fd_set readfds;
 342     int n;
 343     struct timeval tv = {
 344         .tv_sec = 1,
 345         .tv_usec = 0,
 346     };
 347     unsigned char buf[1024];
 348
 349     n = write(fd, &req, sizeof(req));
 350     if (n < 0) {
 351         return errno;
 352     }
 353     if (n != sizeof(req)) {
 354         return EFAULT;
 355     }
 356
 357     FD_ZERO(&readfds);
 358     FD_SET(fd, &readfds);
 359
 360     /* wait for a second */
 361     n = select(fd + 1, &readfds, NULL, NULL, &tv);
 362     if (n != 1) {
 363         return errno;
 364     }
 365
 366     n = read(fd, &buf, sizeof(buf));
 367     if (n < sizeof(struct tpm_resp_hdr)) {
 368         return EFAULT;
 369     }
 370
 371     resp = (struct tpm_resp_hdr *)buf;
 372     /* check the header */
 373     if (be16_to_cpu(resp->tag) != TPM_TAG_RSP_COMMAND ||
 374         be32_to_cpu(resp->len) != n) {
 375         return EBADMSG;
 376     }
 377
 378     return 0;
 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  * From /dev/tpm0 create /sys/class/misc/tpm0/device/cancel
 386  */
 387 static int tpm_passthrough_open_sysfs_cancel(TPMBackend *tb)
 388 {
 389     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 390     int fd = -1;
 391     char *dev;
 392     char path[PATH_MAX];
 393
 394     if (tb->cancel_path) {
 395         fd = qemu_open(tb->cancel_path, O_WRONLY);
 396         if (fd < 0) {
 397             error_report("Could not open TPM cancel path : %s",
 398                          strerror(errno));
 399         }
 400         return fd;
 401     }
 402
 403     dev = strrchr(tpm_pt->tpm_dev, '/');
 404     if (dev) {
 405         dev++;
 406         if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
 407                      dev) < sizeof(path)) {
 408             fd = qemu_open(path, O_WRONLY);
 409             if (fd >= 0) {
 410                 tb->cancel_path = g_strdup(path);
 411             } else {
 412                 error_report("tpm_passthrough: Could not open TPM cancel "
 413                              "path %s : %s", path, strerror(errno));
 414             }
 415         }
 416     } else {
 417        error_report("tpm_passthrough: Bad TPM device path %s",
 418                     tpm_pt->tpm_dev);
 419     }
 420
 421     return fd;
 422 }
 423
 424 static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)
 425 {
 426     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 427     const char *value;
 428
 429     value = qemu_opt_get(opts, "cancel-path");
 430     tb->cancel_path = g_strdup(value);
 431
 432     value = qemu_opt_get(opts, "path");
 433     if (!value) {
 434         value = TPM_PASSTHROUGH_DEFAULT_DEVICE;
 435     }
 436
 437     tpm_pt->tpm_dev = g_strdup(value);
 438
 439     tb->path = g_strdup(tpm_pt->tpm_dev);
 440
 441     tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
 442     if (tpm_pt->tpm_fd < 0) {
 443         error_report("Cannot access TPM device using '%s': %s",
 444                      tpm_pt->tpm_dev, strerror(errno));
 445         goto err_free_parameters;
 446     }
 447
 448     if (tpm_passthrough_test_tpmdev(tpm_pt->tpm_fd)) {
 449         error_report("'%s' is not a TPM device.",
 450                      tpm_pt->tpm_dev);
 451         goto err_close_tpmdev;
 452     }
 453
 454     return 0;
 455
 456  err_close_tpmdev:
 457     qemu_close(tpm_pt->tpm_fd);
 458     tpm_pt->tpm_fd = -1;
 459
 460  err_free_parameters:
 461     g_free(tb->path);
 462     tb->path = NULL;
 463
 464     g_free(tpm_pt->tpm_dev);
 465     tpm_pt->tpm_dev = NULL;
 466
 467     return 1;
 468 }
 469
 470 static TPMBackend *tpm_passthrough_create(QemuOpts *opts, const char *id)
 471 {
 472     Object *obj = object_new(TYPE_TPM_PASSTHROUGH);
 473     TPMBackend *tb = TPM_BACKEND(obj);
 474     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 475
 476     tb->id = g_strdup(id);
 477     /* let frontend set the fe_model to proper value */
 478     tb->fe_model = -1;
 479
 480     tb->ops = &tpm_passthrough_driver;
 481
 482     if (tpm_passthrough_handle_device_opts(opts, tb)) {
 483         goto err_exit;
 484     }
 485
 486     tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tb);
 487     if (tpm_pt->cancel_fd < 0) {
 488         goto err_exit;
 489     }
 490
 491     return tb;
 492
 493 err_exit:
 494     g_free(tb->id);
 495
 496     return NULL;
 497 }
 498
 499 static void tpm_passthrough_destroy(TPMBackend *tb)
 500 {
 501     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 502
 503     tpm_passthrough_cancel_cmd(tb);
 504
 505     tpm_backend_thread_end(&tpm_pt->tbt);
 506
 507     qemu_close(tpm_pt->tpm_fd);
 508     qemu_close(tpm_pt->cancel_fd);
 509
 510     g_free(tb->id);
 511     g_free(tb->path);
 512     g_free(tb->cancel_path);
 513     g_free(tpm_pt->tpm_dev);
 514 }
 515
 516 static const QemuOptDesc tpm_passthrough_cmdline_opts[] = {
 517     TPM_STANDARD_CMDLINE_OPTS,
 518     {
 519         .name = "cancel-path",
 520         .type = QEMU_OPT_STRING,
 521         .help = "Sysfs file entry for canceling TPM commands",
 522     },
 523     {
 524         .name = "path",
 525         .type = QEMU_OPT_STRING,
 526         .help = "Path to TPM device on the host",
 527     },
 528     { /* end of list */ },
 529 };
 530
 531 static const TPMDriverOps tpm_passthrough_driver = {
 532     .type                     = TPM_TYPE_PASSTHROUGH,
 533     .opts                     = tpm_passthrough_cmdline_opts,
 534     .desc                     = tpm_passthrough_create_desc,
 535     .create                   = tpm_passthrough_create,
 536     .destroy                  = tpm_passthrough_destroy,
 537     .init                     = tpm_passthrough_init,
 538     .startup_tpm              = tpm_passthrough_startup_tpm,
 539     .realloc_buffer           = tpm_passthrough_realloc_buffer,
 540     .reset                    = tpm_passthrough_reset,
 541     .had_startup_error        = tpm_passthrough_get_startup_error,
 542     .deliver_request          = tpm_passthrough_deliver_request,
 543     .cancel_cmd               = tpm_passthrough_cancel_cmd,
 544     .get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag,
 545 };
 546
 547 static void tpm_passthrough_inst_init(Object *obj)
 548 {
 549 }
 550
 551 static void tpm_passthrough_inst_finalize(Object *obj)
 552 {
 553 }
 554
 555 static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
 556 {
 557     TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);
 558
 559     tbc->ops = &tpm_passthrough_driver;
 560 }
 561
 562 static const TypeInfo tpm_passthrough_info = {
 563     .name = TYPE_TPM_PASSTHROUGH,
 564     .parent = TYPE_TPM_BACKEND,
 565     .instance_size = sizeof(TPMPassthruState),
 566     .class_init = tpm_passthrough_class_init,
 567     .instance_init = tpm_passthrough_inst_init,
 568     .instance_finalize = tpm_passthrough_inst_finalize,
 569 };
 570
 571 static void tpm_passthrough_register(void)
 572 {
 573     type_register_static(&tpm_passthrough_info);
 574     tpm_register_driver(&tpm_passthrough_driver);
 575 }
 576
 577 type_init(tpm_passthrough_register)