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