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