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 */
  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  * Unless path or file descriptor set has been provided by user,
 356  * determine the sysfs cancel file following kernel documentation
 357  * in Documentation/ABI/stable/sysfs-class-tpm.
 358  * From /dev/tpm0 create /sys/class/misc/tpm0/device/cancel
 359  */
 360 static int tpm_passthrough_open_sysfs_cancel(TPMBackend *tb)
 361 {
 362     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 363     int fd = -1;
 364     char *dev;
 365     char path[PATH_MAX];
 366
 367     if (tb->cancel_path) {
 368         fd = qemu_open(tb->cancel_path, O_WRONLY);
 369         if (fd < 0) {
 370             error_report("Could not open TPM cancel path : %s",
 371                          strerror(errno));
 372         }
 373         return fd;
 374     }
 375
 376     dev = strrchr(tpm_pt->tpm_dev, '/');
 377     if (dev) {
 378         dev++;
 379         if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
 380                      dev) < sizeof(path)) {
 381             fd = qemu_open(path, O_WRONLY);
 382             if (fd >= 0) {
 383                 tb->cancel_path = g_strdup(path);
 384             } else {
 385                 error_report("tpm_passthrough: Could not open TPM cancel "
 386                              "path %s : %s", path, strerror(errno));
 387             }
 388         }
 389     } else {
 390        error_report("tpm_passthrough: Bad TPM device path %s",
 391                     tpm_pt->tpm_dev);
 392     }
 393
 394     return fd;
 395 }
 396
 397 static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)
 398 {
 399     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 400     const char *value;
 401
 402     value = qemu_opt_get(opts, "cancel-path");
 403     if (value) {
 404         tb->cancel_path = g_strdup(value);
 405     }
 406
 407     value = qemu_opt_get(opts, "path");
 408     if (!value) {
 409         value = TPM_PASSTHROUGH_DEFAULT_DEVICE;
 410     }
 411
 412     tpm_pt->tpm_dev = g_strdup(value);
 413
 414     tb->path = g_strdup(tpm_pt->tpm_dev);
 415
 416     tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
 417     if (tpm_pt->tpm_fd < 0) {
 418         error_report("Cannot access TPM device using '%s': %s\n",
 419                      tpm_pt->tpm_dev, strerror(errno));
 420         goto err_free_parameters;
 421     }
 422
 423     if (tpm_passthrough_test_tpmdev(tpm_pt->tpm_fd)) {
 424         error_report("'%s' is not a TPM device.\n",
 425                      tpm_pt->tpm_dev);
 426         goto err_close_tpmdev;
 427     }
 428
 429     return 0;
 430
 431  err_close_tpmdev:
 432     qemu_close(tpm_pt->tpm_fd);
 433     tpm_pt->tpm_fd = -1;
 434
 435  err_free_parameters:
 436     g_free(tb->path);
 437     tb->path = NULL;
 438
 439     g_free(tpm_pt->tpm_dev);
 440     tpm_pt->tpm_dev = NULL;
 441
 442     return 1;
 443 }
 444
 445 static TPMBackend *tpm_passthrough_create(QemuOpts *opts, const char *id)
 446 {
 447     Object *obj = object_new(TYPE_TPM_PASSTHROUGH);
 448     TPMBackend *tb = TPM_BACKEND(obj);
 449     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 450
 451     tb->id = g_strdup(id);
 452     /* let frontend set the fe_model to proper value */
 453     tb->fe_model = -1;
 454
 455     tb->ops = &tpm_passthrough_driver;
 456
 457     if (tpm_passthrough_handle_device_opts(opts, tb)) {
 458         goto err_exit;
 459     }
 460
 461     tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tb);
 462     if (tpm_pt->cancel_fd < 0) {
 463         goto err_exit;
 464     }
 465
 466     return tb;
 467
 468 err_exit:
 469     g_free(tb->id);
 470
 471     return NULL;
 472 }
 473
 474 static void tpm_passthrough_destroy(TPMBackend *tb)
 475 {
 476     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 477
 478     tpm_passthrough_cancel_cmd(tb);
 479
 480     tpm_backend_thread_end(&tpm_pt->tbt);
 481
 482     qemu_close(tpm_pt->tpm_fd);
 483     qemu_close(tpm_pt->cancel_fd);
 484
 485     g_free(tb->id);
 486     g_free(tb->path);
 487     g_free(tb->cancel_path);
 488     g_free(tpm_pt->tpm_dev);
 489 }
 490
 491 static const QemuOptDesc tpm_passthrough_cmdline_opts[] = {
 492     TPM_STANDARD_CMDLINE_OPTS,
 493     {
 494         .name = "cancel-path",
 495         .type = QEMU_OPT_STRING,
 496         .help = "Sysfs file entry for canceling TPM commands",
 497     },
 498     {
 499         .name = "path",
 500         .type = QEMU_OPT_STRING,
 501         .help = "Path to TPM device on the host",
 502     },
 503     { /* end of list */ },
 504 };
 505
 506 static const TPMDriverOps tpm_passthrough_driver = {
 507     .type                     = TPM_TYPE_PASSTHROUGH,
 508     .opts                     = tpm_passthrough_cmdline_opts,
 509     .desc                     = tpm_passthrough_create_desc,
 510     .create                   = tpm_passthrough_create,
 511     .destroy                  = tpm_passthrough_destroy,
 512     .init                     = tpm_passthrough_init,
 513     .startup_tpm              = tpm_passthrough_startup_tpm,
 514     .realloc_buffer           = tpm_passthrough_realloc_buffer,
 515     .reset                    = tpm_passthrough_reset,
 516     .had_startup_error        = tpm_passthrough_get_startup_error,
 517     .deliver_request          = tpm_passthrough_deliver_request,
 518     .cancel_cmd               = tpm_passthrough_cancel_cmd,
 519     .get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag,
 520 };
 521
 522 static void tpm_passthrough_inst_init(Object *obj)
 523 {
 524 }
 525
 526 static void tpm_passthrough_inst_finalize(Object *obj)
 527 {
 528 }
 529
 530 static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
 531 {
 532     TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);
 533
 534     tbc->ops = &tpm_passthrough_driver;
 535 }
 536
 537 static const TypeInfo tpm_passthrough_info = {
 538     .name = TYPE_TPM_PASSTHROUGH,
 539     .parent = TYPE_TPM_BACKEND,
 540     .instance_size = sizeof(TPMPassthruState),
 541     .class_init = tpm_passthrough_class_init,
 542     .instance_init = tpm_passthrough_inst_init,
 543     .instance_finalize = tpm_passthrough_inst_finalize,
 544 };
 545
 546 static void tpm_passthrough_register(void)
 547 {
 548     type_register_static(&tpm_passthrough_info);
 549     tpm_register_driver(&tpm_passthrough_driver);
 550 }
 551
 552 type_init(tpm_passthrough_register)