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