backends/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/module.h"
  29 #include "qemu/sockets.h"
  30 #include "sysemu/tpm_backend.h"
  31 #include "sysemu/tpm_util.h"
  32 #include "tpm_int.h"
  33 #include "qapi/clone-visitor.h"
  34 #include "qapi/qapi-visit-tpm.h"
  35 #include "trace.h"
  36
  37 #define TYPE_TPM_PASSTHROUGH "tpm-passthrough"
  38 #define TPM_PASSTHROUGH(obj) \
  39     OBJECT_CHECK(TPMPassthruState, (obj), TYPE_TPM_PASSTHROUGH)
  40
  41 /* data structures */
  42 struct TPMPassthruState {
  43     TPMBackend parent;
  44
  45     TPMPassthroughOptions *options;
  46     const char *tpm_dev;
  47     int tpm_fd;
  48     bool tpm_executing;
  49     bool tpm_op_canceled;
  50     int cancel_fd;
  51
  52     TPMVersion tpm_version;
  53     size_t tpm_buffersize;
  54 };
  55
  56 typedef struct TPMPassthruState TPMPassthruState;
  57
  58 #define TPM_PASSTHROUGH_DEFAULT_DEVICE "/dev/tpm0"
  59
  60 /* functions */
  61
  62 static void tpm_passthrough_cancel_cmd(TPMBackend *tb);
  63
  64 static int tpm_passthrough_unix_read(int fd, uint8_t *buf, uint32_t len)
  65 {
  66     int ret;
  67  reread:
  68     ret = read(fd, buf, len);
  69     if (ret < 0) {
  70         if (errno != EINTR && errno != EAGAIN) {
  71             return -1;
  72         }
  73         goto reread;
  74     }
  75     return ret;
  76 }
  77
  78 static void tpm_passthrough_unix_tx_bufs(TPMPassthruState *tpm_pt,
  79                                          const uint8_t *in, uint32_t in_len,
  80                                          uint8_t *out, uint32_t out_len,
  81                                          bool *selftest_done, Error **errp)
  82 {
  83     ssize_t ret;
  84     bool is_selftest;
  85
  86     /* FIXME: protect shared variables or use other sync mechanism */
  87     tpm_pt->tpm_op_canceled = false;
  88     tpm_pt->tpm_executing = true;
  89     *selftest_done = false;
  90
  91     is_selftest = tpm_util_is_selftest(in, in_len);
  92
  93     ret = qemu_write_full(tpm_pt->tpm_fd, in, in_len);
  94     if (ret != in_len) {
  95         if (!tpm_pt->tpm_op_canceled || errno != ECANCELED) {
  96             error_setg_errno(errp, errno, "tpm_passthrough: error while "
  97                              "transmitting data to TPM");
  98         }
  99         goto err_exit;
 100     }
 101
 102     tpm_pt->tpm_executing = false;
 103
 104     ret = tpm_passthrough_unix_read(tpm_pt->tpm_fd, out, out_len);
 105     if (ret < 0) {
 106         if (!tpm_pt->tpm_op_canceled || errno != ECANCELED) {
 107             error_setg_errno(errp, errno, "tpm_passthrough: error while "
 108                              "reading data from TPM");
 109         }
 110     } else if (ret < sizeof(struct tpm_resp_hdr) ||
 111                tpm_cmd_get_size(out) != ret) {
 112         ret = -1;
 113         error_setg_errno(errp, errno, "tpm_passthrough: received invalid "
 114                      "response packet from TPM");
 115     }
 116
 117     if (is_selftest && (ret >= sizeof(struct tpm_resp_hdr))) {
 118         *selftest_done = tpm_cmd_get_errcode(out) == 0;
 119     }
 120
 121 err_exit:
 122     if (ret < 0) {
 123         tpm_util_write_fatal_error_response(out, out_len);
 124     }
 125
 126     tpm_pt->tpm_executing = false;
 127 }
 128
 129 static void tpm_passthrough_handle_request(TPMBackend *tb, TPMBackendCmd *cmd,
 130                                            Error **errp)
 131 {
 132     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 133
 134     trace_tpm_passthrough_handle_request(cmd);
 135
 136     tpm_passthrough_unix_tx_bufs(tpm_pt, cmd->in, cmd->in_len,
 137                                  cmd->out, cmd->out_len, &cmd->selftest_done,
 138                                  errp);
 139 }
 140
 141 static void tpm_passthrough_reset(TPMBackend *tb)
 142 {
 143     trace_tpm_passthrough_reset();
 144
 145     tpm_passthrough_cancel_cmd(tb);
 146 }
 147
 148 static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)
 149 {
 150     return false;
 151 }
 152
 153 static int tpm_passthrough_reset_tpm_established_flag(TPMBackend *tb,
 154                                                       uint8_t locty)
 155 {
 156     /* only a TPM 2.0 will support this */
 157     return 0;
 158 }
 159
 160 static void tpm_passthrough_cancel_cmd(TPMBackend *tb)
 161 {
 162     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 163     int n;
 164
 165     /*
 166      * As of Linux 3.7 the tpm_tis driver does not properly cancel
 167      * commands on all TPM manufacturers' TPMs.
 168      * Only cancel if we're busy so we don't cancel someone else's
 169      * command, e.g., a command executed on the host.
 170      */
 171     if (tpm_pt->tpm_executing) {
 172         if (tpm_pt->cancel_fd >= 0) {
 173             tpm_pt->tpm_op_canceled = true;
 174             n = write(tpm_pt->cancel_fd, "-", 1);
 175             if (n != 1) {
 176                 error_report("Canceling TPM command failed: %s",
 177                              strerror(errno));
 178             }
 179         } else {
 180             error_report("Cannot cancel TPM command due to missing "
 181                          "TPM sysfs cancel entry");
 182         }
 183     }
 184 }
 185
 186 static TPMVersion tpm_passthrough_get_tpm_version(TPMBackend *tb)
 187 {
 188     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 189
 190     return tpm_pt->tpm_version;
 191 }
 192
 193 static size_t tpm_passthrough_get_buffer_size(TPMBackend *tb)
 194 {
 195     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 196     int ret;
 197
 198     ret = tpm_util_get_buffer_size(tpm_pt->tpm_fd, tpm_pt->tpm_version,
 199                                    &tpm_pt->tpm_buffersize);
 200     if (ret < 0) {
 201         tpm_pt->tpm_buffersize = 4096;
 202     }
 203     return tpm_pt->tpm_buffersize;
 204 }
 205
 206 /*
 207  * Unless path or file descriptor set has been provided by user,
 208  * determine the sysfs cancel file following kernel documentation
 209  * in Documentation/ABI/stable/sysfs-class-tpm.
 210  * From /dev/tpm0 create /sys/class/tpm/tpm0/device/cancel
 211  * before 4.0: /sys/class/misc/tpm0/device/cancel
 212  */
 213 static int tpm_passthrough_open_sysfs_cancel(TPMPassthruState *tpm_pt)
 214 {
 215     int fd = -1;
 216     char *dev;
 217     char path[PATH_MAX];
 218
 219     if (tpm_pt->options->cancel_path) {
 220         fd = qemu_open(tpm_pt->options->cancel_path, O_WRONLY);
 221         if (fd < 0) {
 222             error_report("tpm_passthrough: Could not open TPM cancel path: %s",
 223                          strerror(errno));
 224         }
 225         return fd;
 226     }
 227
 228     dev = strrchr(tpm_pt->tpm_dev, '/');
 229     if (!dev) {
 230         error_report("tpm_passthrough: Bad TPM device path %s",
 231                      tpm_pt->tpm_dev);
 232         return -1;
 233     }
 234
 235     dev++;
 236     if (snprintf(path, sizeof(path), "/sys/class/tpm/%s/device/cancel",
 237                  dev) < sizeof(path)) {
 238         fd = qemu_open(path, O_WRONLY);
 239         if (fd < 0) {
 240             if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
 241                          dev) < sizeof(path)) {
 242                 fd = qemu_open(path, O_WRONLY);
 243             }
 244         }
 245     }
 246
 247     if (fd < 0) {
 248         error_report("tpm_passthrough: Could not guess TPM cancel path");
 249     } else {
 250         tpm_pt->options->cancel_path = g_strdup(path);
 251     }
 252
 253     return fd;
 254 }
 255
 256 static int
 257 tpm_passthrough_handle_device_opts(TPMPassthruState *tpm_pt, QemuOpts *opts)
 258 {
 259     const char *value;
 260
 261     value = qemu_opt_get(opts, "cancel-path");
 262     if (value) {
 263         tpm_pt->options->cancel_path = g_strdup(value);
 264         tpm_pt->options->has_cancel_path = true;
 265     }
 266
 267     value = qemu_opt_get(opts, "path");
 268     if (value) {
 269         tpm_pt->options->has_path = true;
 270         tpm_pt->options->path = g_strdup(value);
 271     }
 272
 273     tpm_pt->tpm_dev = value ? value : TPM_PASSTHROUGH_DEFAULT_DEVICE;
 274     tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
 275     if (tpm_pt->tpm_fd < 0) {
 276         error_report("Cannot access TPM device using '%s': %s",
 277                      tpm_pt->tpm_dev, strerror(errno));
 278         return -1;
 279     }
 280
 281     if (tpm_util_test_tpmdev(tpm_pt->tpm_fd, &tpm_pt->tpm_version)) {
 282         error_report("'%s' is not a TPM device.",
 283                      tpm_pt->tpm_dev);
 284         return -1;
 285     }
 286
 287     tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tpm_pt);
 288     if (tpm_pt->cancel_fd < 0) {
 289         return -1;
 290     }
 291
 292     return 0;
 293 }
 294
 295 static TPMBackend *tpm_passthrough_create(QemuOpts *opts)
 296 {
 297     Object *obj = object_new(TYPE_TPM_PASSTHROUGH);
 298
 299     if (tpm_passthrough_handle_device_opts(TPM_PASSTHROUGH(obj), opts)) {
 300         object_unref(obj);
 301         return NULL;
 302     }
 303
 304     return TPM_BACKEND(obj);
 305 }
 306
 307 static int tpm_passthrough_startup_tpm(TPMBackend *tb, size_t buffersize)
 308 {
 309     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 310
 311     if (buffersize && buffersize < tpm_pt->tpm_buffersize) {
 312         error_report("Requested buffer size of %zu is smaller than host TPM's "
 313                      "fixed buffer size of %zu",
 314                      buffersize, tpm_pt->tpm_buffersize);
 315         return -1;
 316     }
 317
 318     return 0;
 319 }
 320
 321 static TpmTypeOptions *tpm_passthrough_get_tpm_options(TPMBackend *tb)
 322 {
 323     TpmTypeOptions *options = g_new0(TpmTypeOptions, 1);
 324
 325     options->type = TPM_TYPE_OPTIONS_KIND_PASSTHROUGH;
 326     options->u.passthrough.data = QAPI_CLONE(TPMPassthroughOptions,
 327                                              TPM_PASSTHROUGH(tb)->options);
 328
 329     return options;
 330 }
 331
 332 static const QemuOptDesc tpm_passthrough_cmdline_opts[] = {
 333     TPM_STANDARD_CMDLINE_OPTS,
 334     {
 335         .name = "cancel-path",
 336         .type = QEMU_OPT_STRING,
 337         .help = "Sysfs file entry for canceling TPM commands",
 338     },
 339     {
 340         .name = "path",
 341         .type = QEMU_OPT_STRING,
 342         .help = "Path to TPM device on the host",
 343     },
 344     { /* end of list */ },
 345 };
 346
 347 static void tpm_passthrough_inst_init(Object *obj)
 348 {
 349     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
 350
 351     tpm_pt->options = g_new0(TPMPassthroughOptions, 1);
 352     tpm_pt->tpm_fd = -1;
 353     tpm_pt->cancel_fd = -1;
 354 }
 355
 356 static void tpm_passthrough_inst_finalize(Object *obj)
 357 {
 358     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
 359
 360     tpm_passthrough_cancel_cmd(TPM_BACKEND(obj));
 361
 362     if (tpm_pt->tpm_fd >= 0) {
 363         qemu_close(tpm_pt->tpm_fd);
 364     }
 365     if (tpm_pt->cancel_fd >= 0) {
 366         qemu_close(tpm_pt->cancel_fd);
 367     }
 368     qapi_free_TPMPassthroughOptions(tpm_pt->options);
 369 }
 370
 371 static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
 372 {
 373     TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);
 374
 375     tbc->type = TPM_TYPE_PASSTHROUGH;
 376     tbc->opts = tpm_passthrough_cmdline_opts;
 377     tbc->desc = "Passthrough TPM backend driver";
 378     tbc->create = tpm_passthrough_create;
 379     tbc->startup_tpm = tpm_passthrough_startup_tpm;
 380     tbc->reset = tpm_passthrough_reset;
 381     tbc->cancel_cmd = tpm_passthrough_cancel_cmd;
 382     tbc->get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag;
 383     tbc->reset_tpm_established_flag =
 384         tpm_passthrough_reset_tpm_established_flag;
 385     tbc->get_tpm_version = tpm_passthrough_get_tpm_version;
 386     tbc->get_buffer_size = tpm_passthrough_get_buffer_size;
 387     tbc->get_tpm_options = tpm_passthrough_get_tpm_options;
 388     tbc->handle_request = tpm_passthrough_handle_request;
 389 }
 390
 391 static const TypeInfo tpm_passthrough_info = {
 392     .name = TYPE_TPM_PASSTHROUGH,
 393     .parent = TYPE_TPM_BACKEND,
 394     .instance_size = sizeof(TPMPassthruState),
 395     .class_init = tpm_passthrough_class_init,
 396     .instance_init = tpm_passthrough_inst_init,
 397     .instance_finalize = tpm_passthrough_inst_finalize,
 398 };
 399
 400 static void tpm_passthrough_register(void)
 401 {
 402     type_register_static(&tpm_passthrough_info);
 403 }
 404
 405 type_init(tpm_passthrough_register)