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 "qemu/osdep.h"
  26 #include "qemu-common.h"
  27 #include "qemu/error-report.h"
  28 #include "qemu/sockets.h"
  29 #include "sysemu/tpm_backend.h"
  30 #include "tpm_int.h"
  31 #include "hw/hw.h"
  32 #include "hw/i386/pc.h"
  33 #include "qapi/clone-visitor.h"
  34 #include "tpm_tis.h"
  35 #include "tpm_util.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 /* data structures */
  50 struct TPMPassthruState {
  51     TPMBackend parent;
  52
  53     TPMPassthroughOptions *options;
  54     const char *tpm_dev;
  55     int tpm_fd;
  56     bool tpm_executing;
  57     bool tpm_op_canceled;
  58     int cancel_fd;
  59
  60     TPMVersion tpm_version;
  61 };
  62
  63 typedef struct TPMPassthruState TPMPassthruState;
  64
  65 #define TPM_PASSTHROUGH_DEFAULT_DEVICE "/dev/tpm0"
  66
  67 /* functions */
  68
  69 static void tpm_passthrough_cancel_cmd(TPMBackend *tb);
  70
  71 static int tpm_passthrough_unix_write(int fd, const uint8_t *buf, uint32_t len)
  72 {
  73     int ret, remain;
  74
  75     remain = len;
  76     while (remain > 0) {
  77         ret = write(fd, buf, remain);
  78         if (ret < 0) {
  79             if (errno != EINTR && errno != EAGAIN) {
  80                 return -1;
  81             }
  82         } else if (ret == 0) {
  83             break;
  84         } else {
  85             buf += ret;
  86             remain -= ret;
  87         }
  88     }
  89     return len - remain;
  90 }
  91
  92 static int tpm_passthrough_unix_read(int fd, uint8_t *buf, uint32_t len)
  93 {
  94     int ret;
  95  reread:
  96     ret = read(fd, buf, len);
  97     if (ret < 0) {
  98         if (errno != EINTR && errno != EAGAIN) {
  99             return -1;
 100         }
 101         goto reread;
 102     }
 103     return ret;
 104 }
 105
 106 static uint32_t tpm_passthrough_get_size_from_buffer(const uint8_t *buf)
 107 {
 108     struct tpm_resp_hdr *resp = (struct tpm_resp_hdr *)buf;
 109
 110     return be32_to_cpu(resp->len);
 111 }
 112
 113 /*
 114  * Write an error message in the given output buffer.
 115  */
 116 static void tpm_write_fatal_error_response(uint8_t *out, uint32_t out_len)
 117 {
 118     if (out_len >= sizeof(struct tpm_resp_hdr)) {
 119         struct tpm_resp_hdr *resp = (struct tpm_resp_hdr *)out;
 120
 121         resp->tag = cpu_to_be16(TPM_TAG_RSP_COMMAND);
 122         resp->len = cpu_to_be32(sizeof(struct tpm_resp_hdr));
 123         resp->errcode = cpu_to_be32(TPM_FAIL);
 124     }
 125 }
 126
 127 static bool tpm_passthrough_is_selftest(const uint8_t *in, uint32_t in_len)
 128 {
 129     struct tpm_req_hdr *hdr = (struct tpm_req_hdr *)in;
 130
 131     if (in_len >= sizeof(*hdr)) {
 132         return (be32_to_cpu(hdr->ordinal) == TPM_ORD_ContinueSelfTest);
 133     }
 134
 135     return false;
 136 }
 137
 138 static int tpm_passthrough_unix_tx_bufs(TPMPassthruState *tpm_pt,
 139                                         const uint8_t *in, uint32_t in_len,
 140                                         uint8_t *out, uint32_t out_len,
 141                                         bool *selftest_done)
 142 {
 143     int ret;
 144     bool is_selftest;
 145     const struct tpm_resp_hdr *hdr;
 146
 147     tpm_pt->tpm_op_canceled = false;
 148     tpm_pt->tpm_executing = true;
 149     *selftest_done = false;
 150
 151     is_selftest = tpm_passthrough_is_selftest(in, in_len);
 152
 153     ret = tpm_passthrough_unix_write(tpm_pt->tpm_fd, in, in_len);
 154     if (ret != in_len) {
 155         if (!tpm_pt->tpm_op_canceled || errno != ECANCELED) {
 156             error_report("tpm_passthrough: error while transmitting data "
 157                          "to TPM: %s (%i)",
 158                          strerror(errno), errno);
 159         }
 160         goto err_exit;
 161     }
 162
 163     tpm_pt->tpm_executing = false;
 164
 165     ret = tpm_passthrough_unix_read(tpm_pt->tpm_fd, out, out_len);
 166     if (ret < 0) {
 167         if (!tpm_pt->tpm_op_canceled || errno != ECANCELED) {
 168             error_report("tpm_passthrough: error while reading data from "
 169                          "TPM: %s (%i)",
 170                          strerror(errno), errno);
 171         }
 172     } else if (ret < sizeof(struct tpm_resp_hdr) ||
 173                tpm_passthrough_get_size_from_buffer(out) != ret) {
 174         ret = -1;
 175         error_report("tpm_passthrough: received invalid response "
 176                      "packet from TPM");
 177     }
 178
 179     if (is_selftest && (ret >= sizeof(struct tpm_resp_hdr))) {
 180         hdr = (struct tpm_resp_hdr *)out;
 181         *selftest_done = (be32_to_cpu(hdr->errcode) == 0);
 182     }
 183
 184 err_exit:
 185     if (ret < 0) {
 186         tpm_write_fatal_error_response(out, out_len);
 187     }
 188
 189     tpm_pt->tpm_executing = false;
 190
 191     return ret;
 192 }
 193
 194 static int tpm_passthrough_unix_transfer(TPMPassthruState *tpm_pt,
 195                                          const TPMLocality *locty_data,
 196                                          bool *selftest_done)
 197 {
 198     return tpm_passthrough_unix_tx_bufs(tpm_pt,
 199                                         locty_data->w_buffer.buffer,
 200                                         locty_data->w_offset,
 201                                         locty_data->r_buffer.buffer,
 202                                         locty_data->r_buffer.size,
 203                                         selftest_done);
 204 }
 205
 206 static void tpm_passthrough_handle_request(TPMBackend *tb, TPMBackendCmd cmd)
 207 {
 208     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 209     bool selftest_done = false;
 210
 211     DPRINTF("tpm_passthrough: processing command type %d\n", cmd);
 212
 213     switch (cmd) {
 214     case TPM_BACKEND_CMD_PROCESS_CMD:
 215         tpm_passthrough_unix_transfer(tpm_pt,
 216                                       tb->tpm_state->locty_data,
 217                                       &selftest_done);
 218
 219         tb->recv_data_callback(tb->tpm_state,
 220                                tb->tpm_state->locty_number,
 221                                selftest_done);
 222         break;
 223     case TPM_BACKEND_CMD_INIT:
 224     case TPM_BACKEND_CMD_END:
 225     case TPM_BACKEND_CMD_TPM_RESET:
 226         /* nothing to do */
 227         break;
 228     }
 229 }
 230
 231 static void tpm_passthrough_reset(TPMBackend *tb)
 232 {
 233     DPRINTF("tpm_passthrough: CALL TO TPM_RESET!\n");
 234
 235     tpm_passthrough_cancel_cmd(tb);
 236 }
 237
 238 static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)
 239 {
 240     return false;
 241 }
 242
 243 static int tpm_passthrough_reset_tpm_established_flag(TPMBackend *tb,
 244                                                       uint8_t locty)
 245 {
 246     /* only a TPM 2.0 will support this */
 247     return 0;
 248 }
 249
 250 static size_t tpm_passthrough_realloc_buffer(TPMSizedBuffer *sb)
 251 {
 252     size_t wanted_size = 4096; /* Linux tpm.c buffer size */
 253
 254     if (sb->size != wanted_size) {
 255         sb->buffer = g_realloc(sb->buffer, wanted_size);
 256         sb->size = wanted_size;
 257     }
 258     return sb->size;
 259 }
 260
 261 static void tpm_passthrough_cancel_cmd(TPMBackend *tb)
 262 {
 263     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 264     int n;
 265
 266     /*
 267      * As of Linux 3.7 the tpm_tis driver does not properly cancel
 268      * commands on all TPM manufacturers' TPMs.
 269      * Only cancel if we're busy so we don't cancel someone else's
 270      * command, e.g., a command executed on the host.
 271      */
 272     if (tpm_pt->tpm_executing) {
 273         if (tpm_pt->cancel_fd >= 0) {
 274             n = write(tpm_pt->cancel_fd, "-", 1);
 275             if (n != 1) {
 276                 error_report("Canceling TPM command failed: %s",
 277                              strerror(errno));
 278             } else {
 279                 tpm_pt->tpm_op_canceled = true;
 280             }
 281         } else {
 282             error_report("Cannot cancel TPM command due to missing "
 283                          "TPM sysfs cancel entry");
 284         }
 285     }
 286 }
 287
 288 static TPMVersion tpm_passthrough_get_tpm_version(TPMBackend *tb)
 289 {
 290     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 291
 292     return tpm_pt->tpm_version;
 293 }
 294
 295 /*
 296  * Unless path or file descriptor set has been provided by user,
 297  * determine the sysfs cancel file following kernel documentation
 298  * in Documentation/ABI/stable/sysfs-class-tpm.
 299  * From /dev/tpm0 create /sys/class/misc/tpm0/device/cancel
 300  */
 301 static int tpm_passthrough_open_sysfs_cancel(TPMPassthruState *tpm_pt)
 302 {
 303     int fd = -1;
 304     char *dev;
 305     char path[PATH_MAX];
 306
 307     if (tpm_pt->options->cancel_path) {
 308         fd = qemu_open(tpm_pt->options->cancel_path, O_WRONLY);
 309         if (fd < 0) {
 310             error_report("Could not open TPM cancel path : %s",
 311                          strerror(errno));
 312         }
 313         return fd;
 314     }
 315
 316     dev = strrchr(tpm_pt->tpm_dev, '/');
 317     if (dev) {
 318         dev++;
 319         if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
 320                      dev) < sizeof(path)) {
 321             fd = qemu_open(path, O_WRONLY);
 322             if (fd >= 0) {
 323                 tpm_pt->options->cancel_path = g_strdup(path);
 324             } else {
 325                 error_report("tpm_passthrough: Could not open TPM cancel "
 326                              "path %s : %s", path, strerror(errno));
 327             }
 328         }
 329     } else {
 330        error_report("tpm_passthrough: Bad TPM device path %s",
 331                     tpm_pt->tpm_dev);
 332     }
 333
 334     return fd;
 335 }
 336
 337 static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)
 338 {
 339     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 340     const char *value;
 341
 342     value = qemu_opt_get(opts, "cancel-path");
 343     if (value) {
 344         tpm_pt->options->cancel_path = g_strdup(value);
 345         tpm_pt->options->has_cancel_path = true;
 346     }
 347
 348     value = qemu_opt_get(opts, "path");
 349     if (value) {
 350         tpm_pt->options->has_path = true;
 351         tpm_pt->options->path = g_strdup(value);
 352     }
 353
 354     tpm_pt->tpm_dev = value ? value : TPM_PASSTHROUGH_DEFAULT_DEVICE;
 355     tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
 356     if (tpm_pt->tpm_fd < 0) {
 357         error_report("Cannot access TPM device using '%s': %s",
 358                      tpm_pt->tpm_dev, strerror(errno));
 359         goto err_free_parameters;
 360     }
 361
 362     if (tpm_util_test_tpmdev(tpm_pt->tpm_fd, &tpm_pt->tpm_version)) {
 363         error_report("'%s' is not a TPM device.",
 364                      tpm_pt->tpm_dev);
 365         goto err_close_tpmdev;
 366     }
 367
 368     return 0;
 369
 370  err_close_tpmdev:
 371     qemu_close(tpm_pt->tpm_fd);
 372     tpm_pt->tpm_fd = -1;
 373
 374  err_free_parameters:
 375     qapi_free_TPMPassthroughOptions(tpm_pt->options);
 376     tpm_pt->options = NULL;
 377     tpm_pt->tpm_dev = NULL;
 378
 379     return 1;
 380 }
 381
 382 static TPMBackend *tpm_passthrough_create(QemuOpts *opts, const char *id)
 383 {
 384     Object *obj = object_new(TYPE_TPM_PASSTHROUGH);
 385     TPMBackend *tb = TPM_BACKEND(obj);
 386     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 387
 388     tb->id = g_strdup(id);
 389
 390     if (tpm_passthrough_handle_device_opts(opts, tb)) {
 391         goto err_exit;
 392     }
 393
 394     tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tpm_pt);
 395     if (tpm_pt->cancel_fd < 0) {
 396         goto err_exit;
 397     }
 398
 399     return tb;
 400
 401 err_exit:
 402     object_unref(obj);
 403
 404     return NULL;
 405 }
 406
 407 static TpmTypeOptions *tpm_passthrough_get_tpm_options(TPMBackend *tb)
 408 {
 409     TpmTypeOptions *options = g_new0(TpmTypeOptions, 1);
 410
 411     options->type = TPM_TYPE_OPTIONS_KIND_PASSTHROUGH;
 412     options->u.passthrough.data = QAPI_CLONE(TPMPassthroughOptions,
 413                                              TPM_PASSTHROUGH(tb)->options);
 414
 415     return options;
 416 }
 417
 418 static const QemuOptDesc tpm_passthrough_cmdline_opts[] = {
 419     TPM_STANDARD_CMDLINE_OPTS,
 420     {
 421         .name = "cancel-path",
 422         .type = QEMU_OPT_STRING,
 423         .help = "Sysfs file entry for canceling TPM commands",
 424     },
 425     {
 426         .name = "path",
 427         .type = QEMU_OPT_STRING,
 428         .help = "Path to TPM device on the host",
 429     },
 430     { /* end of list */ },
 431 };
 432
 433 static const TPMDriverOps tpm_passthrough_driver = {
 434     .type                     = TPM_TYPE_PASSTHROUGH,
 435     .opts                     = tpm_passthrough_cmdline_opts,
 436     .desc                     = "Passthrough TPM backend driver",
 437     .create                   = tpm_passthrough_create,
 438     .realloc_buffer           = tpm_passthrough_realloc_buffer,
 439     .reset                    = tpm_passthrough_reset,
 440     .cancel_cmd               = tpm_passthrough_cancel_cmd,
 441     .get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag,
 442     .reset_tpm_established_flag = tpm_passthrough_reset_tpm_established_flag,
 443     .get_tpm_version          = tpm_passthrough_get_tpm_version,
 444     .get_tpm_options          = tpm_passthrough_get_tpm_options,
 445 };
 446
 447 static void tpm_passthrough_inst_init(Object *obj)
 448 {
 449     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
 450
 451     tpm_pt->options = g_new0(TPMPassthroughOptions, 1);
 452     tpm_pt->tpm_fd = -1;
 453     tpm_pt->cancel_fd = -1;
 454 }
 455
 456 static void tpm_passthrough_inst_finalize(Object *obj)
 457 {
 458     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
 459
 460     tpm_passthrough_cancel_cmd(TPM_BACKEND(obj));
 461
 462     qemu_close(tpm_pt->tpm_fd);
 463     qemu_close(tpm_pt->cancel_fd);
 464     qapi_free_TPMPassthroughOptions(tpm_pt->options);
 465 }
 466
 467 static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
 468 {
 469     TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);
 470
 471     tbc->ops = &tpm_passthrough_driver;
 472     tbc->handle_request = tpm_passthrough_handle_request;
 473 }
 474
 475 static const TypeInfo tpm_passthrough_info = {
 476     .name = TYPE_TPM_PASSTHROUGH,
 477     .parent = TYPE_TPM_BACKEND,
 478     .instance_size = sizeof(TPMPassthruState),
 479     .class_init = tpm_passthrough_class_init,
 480     .instance_init = tpm_passthrough_inst_init,
 481     .instance_finalize = tpm_passthrough_inst_finalize,
 482 };
 483
 484 static void tpm_passthrough_register(void)
 485 {
 486     type_register_static(&tpm_passthrough_info);
 487     tpm_register_driver(&tpm_passthrough_driver);
 488 }
 489
 490 type_init(tpm_passthrough_register)