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 "qapi/clone-visitor.h"
  33 #include "tpm_util.h"
  34
  35 #define DEBUG_TPM 0
  36
  37 #define DPRINTF(fmt, ...) do { \
  38     if (DEBUG_TPM) { \
  39         fprintf(stderr, fmt, ## __VA_ARGS__); \
  40     } \
  41 } while (0)
  42
  43 #define TYPE_TPM_PASSTHROUGH "tpm-passthrough"
  44 #define TPM_PASSTHROUGH(obj) \
  45     OBJECT_CHECK(TPMPassthruState, (obj), TYPE_TPM_PASSTHROUGH)
  46
  47 /* data structures */
  48 struct TPMPassthruState {
  49     TPMBackend parent;
  50
  51     TPMPassthroughOptions *options;
  52     const char *tpm_dev;
  53     int tpm_fd;
  54     bool tpm_executing;
  55     bool tpm_op_canceled;
  56     int cancel_fd;
  57
  58     TPMVersion tpm_version;
  59     size_t tpm_buffersize;
  60 };
  61
  62 typedef struct TPMPassthruState TPMPassthruState;
  63
  64 #define TPM_PASSTHROUGH_DEFAULT_DEVICE "/dev/tpm0"
  65
  66 /* functions */
  67
  68 static void tpm_passthrough_cancel_cmd(TPMBackend *tb);
  69
  70 static int tpm_passthrough_unix_read(int fd, uint8_t *buf, uint32_t len)
  71 {
  72     int ret;
  73  reread:
  74     ret = read(fd, buf, len);
  75     if (ret < 0) {
  76         if (errno != EINTR && errno != EAGAIN) {
  77             return -1;
  78         }
  79         goto reread;
  80     }
  81     return ret;
  82 }
  83
  84 static void 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, Error **errp)
  88 {
  89     ssize_t ret;
  90     bool is_selftest;
  91
  92     /* FIXME: protect shared variables or use other sync mechanism */
  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, in, in_len);
 100     if (ret != in_len) {
 101         if (!tpm_pt->tpm_op_canceled || errno != ECANCELED) {
 102             error_setg_errno(errp, errno, "tpm_passthrough: error while "
 103                              "transmitting data to TPM");
 104         }
 105         goto err_exit;
 106     }
 107
 108     tpm_pt->tpm_executing = false;
 109
 110     ret = tpm_passthrough_unix_read(tpm_pt->tpm_fd, out, out_len);
 111     if (ret < 0) {
 112         if (!tpm_pt->tpm_op_canceled || errno != ECANCELED) {
 113             error_setg_errno(errp, errno, "tpm_passthrough: error while "
 114                              "reading data from TPM");
 115         }
 116     } else if (ret < sizeof(struct tpm_resp_hdr) ||
 117                tpm_cmd_get_size(out) != ret) {
 118         ret = -1;
 119         error_setg_errno(errp, errno, "tpm_passthrough: received invalid "
 120                      "response packet from TPM");
 121     }
 122
 123     if (is_selftest && (ret >= sizeof(struct tpm_resp_hdr))) {
 124         *selftest_done = tpm_cmd_get_errcode(out) == 0;
 125     }
 126
 127 err_exit:
 128     if (ret < 0) {
 129         tpm_util_write_fatal_error_response(out, out_len);
 130     }
 131
 132     tpm_pt->tpm_executing = false;
 133 }
 134
 135 static void tpm_passthrough_handle_request(TPMBackend *tb, TPMBackendCmd *cmd,
 136                                            Error **errp)
 137 {
 138     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 139
 140     DPRINTF("tpm_passthrough: processing command %p\n", cmd);
 141
 142     tpm_passthrough_unix_tx_bufs(tpm_pt, cmd->in, cmd->in_len,
 143                                  cmd->out, cmd->out_len, &cmd->selftest_done,
 144                                  errp);
 145 }
 146
 147 static void tpm_passthrough_reset(TPMBackend *tb)
 148 {
 149     DPRINTF("tpm_passthrough: CALL TO TPM_RESET!\n");
 150
 151     tpm_passthrough_cancel_cmd(tb);
 152 }
 153
 154 static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)
 155 {
 156     return false;
 157 }
 158
 159 static int tpm_passthrough_reset_tpm_established_flag(TPMBackend *tb,
 160                                                       uint8_t locty)
 161 {
 162     /* only a TPM 2.0 will support this */
 163     return 0;
 164 }
 165
 166 static void tpm_passthrough_cancel_cmd(TPMBackend *tb)
 167 {
 168     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 169     int n;
 170
 171     /*
 172      * As of Linux 3.7 the tpm_tis driver does not properly cancel
 173      * commands on all TPM manufacturers' TPMs.
 174      * Only cancel if we're busy so we don't cancel someone else's
 175      * command, e.g., a command executed on the host.
 176      */
 177     if (tpm_pt->tpm_executing) {
 178         if (tpm_pt->cancel_fd >= 0) {
 179             tpm_pt->tpm_op_canceled = true;
 180             n = write(tpm_pt->cancel_fd, "-", 1);
 181             if (n != 1) {
 182                 error_report("Canceling TPM command failed: %s",
 183                              strerror(errno));
 184             }
 185         } else {
 186             error_report("Cannot cancel TPM command due to missing "
 187                          "TPM sysfs cancel entry");
 188         }
 189     }
 190 }
 191
 192 static TPMVersion tpm_passthrough_get_tpm_version(TPMBackend *tb)
 193 {
 194     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 195
 196     return tpm_pt->tpm_version;
 197 }
 198
 199 static size_t tpm_passthrough_get_buffer_size(TPMBackend *tb)
 200 {
 201     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 202     int ret;
 203
 204     ret = tpm_util_get_buffer_size(tpm_pt->tpm_fd, tpm_pt->tpm_version,
 205                                    &tpm_pt->tpm_buffersize);
 206     if (ret < 0) {
 207         tpm_pt->tpm_buffersize = 4096;
 208     }
 209     return tpm_pt->tpm_buffersize;
 210 }
 211
 212 /*
 213  * Unless path or file descriptor set has been provided by user,
 214  * determine the sysfs cancel file following kernel documentation
 215  * in Documentation/ABI/stable/sysfs-class-tpm.
 216  * From /dev/tpm0 create /sys/class/tpm/tpm0/device/cancel
 217  * before 4.0: /sys/class/misc/tpm0/device/cancel
 218  */
 219 static int tpm_passthrough_open_sysfs_cancel(TPMPassthruState *tpm_pt)
 220 {
 221     int fd = -1;
 222     char *dev;
 223     char path[PATH_MAX];
 224
 225     if (tpm_pt->options->cancel_path) {
 226         fd = qemu_open(tpm_pt->options->cancel_path, O_WRONLY);
 227         if (fd < 0) {
 228             error_report("tpm_passthrough: Could not open TPM cancel path: %s",
 229                          strerror(errno));
 230         }
 231         return fd;
 232     }
 233
 234     dev = strrchr(tpm_pt->tpm_dev, '/');
 235     if (!dev) {
 236         error_report("tpm_passthrough: Bad TPM device path %s",
 237                      tpm_pt->tpm_dev);
 238         return -1;
 239     }
 240
 241     dev++;
 242     if (snprintf(path, sizeof(path), "/sys/class/tpm/%s/device/cancel",
 243                  dev) < sizeof(path)) {
 244         fd = qemu_open(path, O_WRONLY);
 245         if (fd < 0) {
 246             if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
 247                          dev) < sizeof(path)) {
 248                 fd = qemu_open(path, O_WRONLY);
 249             }
 250         }
 251     }
 252
 253     if (fd < 0) {
 254         error_report("tpm_passthrough: Could not guess TPM cancel path");
 255     } else {
 256         tpm_pt->options->cancel_path = g_strdup(path);
 257     }
 258
 259     return fd;
 260 }
 261
 262 static int
 263 tpm_passthrough_handle_device_opts(TPMPassthruState *tpm_pt, QemuOpts *opts)
 264 {
 265     const char *value;
 266
 267     value = qemu_opt_get(opts, "cancel-path");
 268     if (value) {
 269         tpm_pt->options->cancel_path = g_strdup(value);
 270         tpm_pt->options->has_cancel_path = true;
 271     }
 272
 273     value = qemu_opt_get(opts, "path");
 274     if (value) {
 275         tpm_pt->options->has_path = true;
 276         tpm_pt->options->path = g_strdup(value);
 277     }
 278
 279     tpm_pt->tpm_dev = value ? value : TPM_PASSTHROUGH_DEFAULT_DEVICE;
 280     tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
 281     if (tpm_pt->tpm_fd < 0) {
 282         error_report("Cannot access TPM device using '%s': %s",
 283                      tpm_pt->tpm_dev, strerror(errno));
 284         return -1;
 285     }
 286
 287     if (tpm_util_test_tpmdev(tpm_pt->tpm_fd, &tpm_pt->tpm_version)) {
 288         error_report("'%s' is not a TPM device.",
 289                      tpm_pt->tpm_dev);
 290         return -1;
 291     }
 292
 293     tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tpm_pt);
 294     if (tpm_pt->cancel_fd < 0) {
 295         return -1;
 296     }
 297
 298     return 0;
 299 }
 300
 301 static TPMBackend *tpm_passthrough_create(QemuOpts *opts)
 302 {
 303     Object *obj = object_new(TYPE_TPM_PASSTHROUGH);
 304
 305     if (tpm_passthrough_handle_device_opts(TPM_PASSTHROUGH(obj), opts)) {
 306         object_unref(obj);
 307         return NULL;
 308     }
 309
 310     return TPM_BACKEND(obj);
 311 }
 312
 313 static int tpm_passthrough_startup_tpm(TPMBackend *tb, size_t buffersize)
 314 {
 315     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 316
 317     if (buffersize && buffersize < tpm_pt->tpm_buffersize) {
 318         error_report("Requested buffer size of %zu is smaller than host TPM's "
 319                      "fixed buffer size of %zu",
 320                      buffersize, tpm_pt->tpm_buffersize);
 321         return -1;
 322     }
 323
 324     return 0;
 325 }
 326
 327 static TpmTypeOptions *tpm_passthrough_get_tpm_options(TPMBackend *tb)
 328 {
 329     TpmTypeOptions *options = g_new0(TpmTypeOptions, 1);
 330
 331     options->type = TPM_TYPE_OPTIONS_KIND_PASSTHROUGH;
 332     options->u.passthrough.data = QAPI_CLONE(TPMPassthroughOptions,
 333                                              TPM_PASSTHROUGH(tb)->options);
 334
 335     return options;
 336 }
 337
 338 static const QemuOptDesc tpm_passthrough_cmdline_opts[] = {
 339     TPM_STANDARD_CMDLINE_OPTS,
 340     {
 341         .name = "cancel-path",
 342         .type = QEMU_OPT_STRING,
 343         .help = "Sysfs file entry for canceling TPM commands",
 344     },
 345     {
 346         .name = "path",
 347         .type = QEMU_OPT_STRING,
 348         .help = "Path to TPM device on the host",
 349     },
 350     { /* end of list */ },
 351 };
 352
 353 static void tpm_passthrough_inst_init(Object *obj)
 354 {
 355     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
 356
 357     tpm_pt->options = g_new0(TPMPassthroughOptions, 1);
 358     tpm_pt->tpm_fd = -1;
 359     tpm_pt->cancel_fd = -1;
 360 }
 361
 362 static void tpm_passthrough_inst_finalize(Object *obj)
 363 {
 364     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
 365
 366     tpm_passthrough_cancel_cmd(TPM_BACKEND(obj));
 367
 368     if (tpm_pt->tpm_fd >= 0) {
 369         qemu_close(tpm_pt->tpm_fd);
 370     }
 371     if (tpm_pt->cancel_fd >= 0) {
 372         qemu_close(tpm_pt->cancel_fd);
 373     }
 374     qapi_free_TPMPassthroughOptions(tpm_pt->options);
 375 }
 376
 377 static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
 378 {
 379     TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);
 380
 381     tbc->type = TPM_TYPE_PASSTHROUGH;
 382     tbc->opts = tpm_passthrough_cmdline_opts;
 383     tbc->desc = "Passthrough TPM backend driver";
 384     tbc->create = tpm_passthrough_create;
 385     tbc->startup_tpm = tpm_passthrough_startup_tpm;
 386     tbc->reset = tpm_passthrough_reset;
 387     tbc->cancel_cmd = tpm_passthrough_cancel_cmd;
 388     tbc->get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag;
 389     tbc->reset_tpm_established_flag =
 390         tpm_passthrough_reset_tpm_established_flag;
 391     tbc->get_tpm_version = tpm_passthrough_get_tpm_version;
 392     tbc->get_buffer_size = tpm_passthrough_get_buffer_size;
 393     tbc->get_tpm_options = tpm_passthrough_get_tpm_options;
 394     tbc->handle_request = tpm_passthrough_handle_request;
 395 }
 396
 397 static const TypeInfo tpm_passthrough_info = {
 398     .name = TYPE_TPM_PASSTHROUGH,
 399     .parent = TYPE_TPM_BACKEND,
 400     .instance_size = sizeof(TPMPassthruState),
 401     .class_init = tpm_passthrough_class_init,
 402     .instance_init = tpm_passthrough_inst_init,
 403     .instance_finalize = tpm_passthrough_inst_finalize,
 404 };
 405
 406 static void tpm_passthrough_register(void)
 407 {
 408     type_register_static(&tpm_passthrough_info);
 409 }
 410
 411 type_init(tpm_passthrough_register)