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 static int tpm_passthrough_unix_tx_bufs(TPMPassthruState *tpm_pt,
  84                                         const uint8_t *in, uint32_t in_len,
  85                                         uint8_t *out, uint32_t out_len,
  86                                         bool *selftest_done)
  87 {
  88     ssize_t ret;
  89     bool is_selftest;
  90
  91     /* FIXME: protect shared variables or use other sync mechanism */
  92     tpm_pt->tpm_op_canceled = false;
  93     tpm_pt->tpm_executing = true;
  94     *selftest_done = false;
  95
  96     is_selftest = tpm_util_is_selftest(in, in_len);
  97
  98     ret = qemu_write_full(tpm_pt->tpm_fd, in, in_len);
  99     if (ret != in_len) {
 100         if (!tpm_pt->tpm_op_canceled || errno != ECANCELED) {
 101             error_report("tpm_passthrough: error while transmitting data "
 102                          "to TPM: %s (%i)",
 103                          strerror(errno), errno);
 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_report("tpm_passthrough: error while reading data from "
 114                          "TPM: %s (%i)",
 115                          strerror(errno), errno);
 116         }
 117     } else if (ret < sizeof(struct tpm_resp_hdr) ||
 118                tpm_cmd_get_size(out) != ret) {
 119         ret = -1;
 120         error_report("tpm_passthrough: received invalid response "
 121                      "packet from TPM");
 122     }
 123
 124     if (is_selftest && (ret >= sizeof(struct tpm_resp_hdr))) {
 125         *selftest_done = tpm_cmd_get_errcode(out) == 0;
 126     }
 127
 128 err_exit:
 129     if (ret < 0) {
 130         tpm_util_write_fatal_error_response(out, out_len);
 131     }
 132
 133     tpm_pt->tpm_executing = false;
 134
 135     return ret;
 136 }
 137
 138 static void tpm_passthrough_handle_request(TPMBackend *tb, TPMBackendCmd *cmd)
 139 {
 140     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 141
 142     DPRINTF("tpm_passthrough: processing command %p\n", cmd);
 143
 144     tpm_passthrough_unix_tx_bufs(tpm_pt, cmd->in, cmd->in_len,
 145                                  cmd->out, cmd->out_len, &cmd->selftest_done);
 146 }
 147
 148 static void tpm_passthrough_reset(TPMBackend *tb)
 149 {
 150     DPRINTF("tpm_passthrough: CALL TO TPM_RESET!\n");
 151
 152     tpm_passthrough_cancel_cmd(tb);
 153 }
 154
 155 static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)
 156 {
 157     return false;
 158 }
 159
 160 static int tpm_passthrough_reset_tpm_established_flag(TPMBackend *tb,
 161                                                       uint8_t locty)
 162 {
 163     /* only a TPM 2.0 will support this */
 164     return 0;
 165 }
 166
 167 static void tpm_passthrough_cancel_cmd(TPMBackend *tb)
 168 {
 169     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 170     int n;
 171
 172     /*
 173      * As of Linux 3.7 the tpm_tis driver does not properly cancel
 174      * commands on all TPM manufacturers' TPMs.
 175      * Only cancel if we're busy so we don't cancel someone else's
 176      * command, e.g., a command executed on the host.
 177      */
 178     if (tpm_pt->tpm_executing) {
 179         if (tpm_pt->cancel_fd >= 0) {
 180             tpm_pt->tpm_op_canceled = true;
 181             n = write(tpm_pt->cancel_fd, "-", 1);
 182             if (n != 1) {
 183                 error_report("Canceling TPM command failed: %s",
 184                              strerror(errno));
 185             }
 186         } else {
 187             error_report("Cannot cancel TPM command due to missing "
 188                          "TPM sysfs cancel entry");
 189         }
 190     }
 191 }
 192
 193 static TPMVersion tpm_passthrough_get_tpm_version(TPMBackend *tb)
 194 {
 195     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 196
 197     return tpm_pt->tpm_version;
 198 }
 199
 200 static size_t tpm_passthrough_get_buffer_size(TPMBackend *tb)
 201 {
 202     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 203     int ret;
 204
 205     ret = tpm_util_get_buffer_size(tpm_pt->tpm_fd, tpm_pt->tpm_version,
 206                                    &tpm_pt->tpm_buffersize);
 207     if (ret < 0) {
 208         tpm_pt->tpm_buffersize = 4096;
 209     }
 210     return tpm_pt->tpm_buffersize;
 211 }
 212
 213 /*
 214  * Unless path or file descriptor set has been provided by user,
 215  * determine the sysfs cancel file following kernel documentation
 216  * in Documentation/ABI/stable/sysfs-class-tpm.
 217  * From /dev/tpm0 create /sys/class/tpm/tpm0/device/cancel
 218  * before 4.0: /sys/class/misc/tpm0/device/cancel
 219  */
 220 static int tpm_passthrough_open_sysfs_cancel(TPMPassthruState *tpm_pt)
 221 {
 222     int fd = -1;
 223     char *dev;
 224     char path[PATH_MAX];
 225
 226     if (tpm_pt->options->cancel_path) {
 227         fd = qemu_open(tpm_pt->options->cancel_path, O_WRONLY);
 228         if (fd < 0) {
 229             error_report("tpm_passthrough: Could not open TPM cancel path: %s",
 230                          strerror(errno));
 231         }
 232         return fd;
 233     }
 234
 235     dev = strrchr(tpm_pt->tpm_dev, '/');
 236     if (!dev) {
 237         error_report("tpm_passthrough: Bad TPM device path %s",
 238                      tpm_pt->tpm_dev);
 239         return -1;
 240     }
 241
 242     dev++;
 243     if (snprintf(path, sizeof(path), "/sys/class/tpm/%s/device/cancel",
 244                  dev) < sizeof(path)) {
 245         fd = qemu_open(path, O_WRONLY);
 246         if (fd < 0) {
 247             if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
 248                          dev) < sizeof(path)) {
 249                 fd = qemu_open(path, O_WRONLY);
 250             }
 251         }
 252     }
 253
 254     if (fd < 0) {
 255         error_report("tpm_passthrough: Could not guess TPM cancel path");
 256     } else {
 257         tpm_pt->options->cancel_path = g_strdup(path);
 258     }
 259
 260     return fd;
 261 }
 262
 263 static int
 264 tpm_passthrough_handle_device_opts(TPMPassthruState *tpm_pt, QemuOpts *opts)
 265 {
 266     const char *value;
 267
 268     value = qemu_opt_get(opts, "cancel-path");
 269     if (value) {
 270         tpm_pt->options->cancel_path = g_strdup(value);
 271         tpm_pt->options->has_cancel_path = true;
 272     }
 273
 274     value = qemu_opt_get(opts, "path");
 275     if (value) {
 276         tpm_pt->options->has_path = true;
 277         tpm_pt->options->path = g_strdup(value);
 278     }
 279
 280     tpm_pt->tpm_dev = value ? value : TPM_PASSTHROUGH_DEFAULT_DEVICE;
 281     tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
 282     if (tpm_pt->tpm_fd < 0) {
 283         error_report("Cannot access TPM device using '%s': %s",
 284                      tpm_pt->tpm_dev, strerror(errno));
 285         return -1;
 286     }
 287
 288     if (tpm_util_test_tpmdev(tpm_pt->tpm_fd, &tpm_pt->tpm_version)) {
 289         error_report("'%s' is not a TPM device.",
 290                      tpm_pt->tpm_dev);
 291         return -1;
 292     }
 293
 294     tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tpm_pt);
 295     if (tpm_pt->cancel_fd < 0) {
 296         return -1;
 297     }
 298
 299     return 0;
 300 }
 301
 302 static TPMBackend *tpm_passthrough_create(QemuOpts *opts)
 303 {
 304     Object *obj = object_new(TYPE_TPM_PASSTHROUGH);
 305
 306     if (tpm_passthrough_handle_device_opts(TPM_PASSTHROUGH(obj), opts)) {
 307         object_unref(obj);
 308         return NULL;
 309     }
 310
 311     return TPM_BACKEND(obj);
 312 }
 313
 314 static int tpm_passthrough_startup_tpm(TPMBackend *tb, size_t buffersize)
 315 {
 316     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 317
 318     if (buffersize && buffersize < tpm_pt->tpm_buffersize) {
 319         error_report("Requested buffer size of %zu is smaller than host TPM's "
 320                      "fixed buffer size of %zu",
 321                      buffersize, tpm_pt->tpm_buffersize);
 322         return -1;
 323     }
 324
 325     return 0;
 326 }
 327
 328 static TpmTypeOptions *tpm_passthrough_get_tpm_options(TPMBackend *tb)
 329 {
 330     TpmTypeOptions *options = g_new0(TpmTypeOptions, 1);
 331
 332     options->type = TPM_TYPE_OPTIONS_KIND_PASSTHROUGH;
 333     options->u.passthrough.data = QAPI_CLONE(TPMPassthroughOptions,
 334                                              TPM_PASSTHROUGH(tb)->options);
 335
 336     return options;
 337 }
 338
 339 static const QemuOptDesc tpm_passthrough_cmdline_opts[] = {
 340     TPM_STANDARD_CMDLINE_OPTS,
 341     {
 342         .name = "cancel-path",
 343         .type = QEMU_OPT_STRING,
 344         .help = "Sysfs file entry for canceling TPM commands",
 345     },
 346     {
 347         .name = "path",
 348         .type = QEMU_OPT_STRING,
 349         .help = "Path to TPM device on the host",
 350     },
 351     { /* end of list */ },
 352 };
 353
 354 static void tpm_passthrough_inst_init(Object *obj)
 355 {
 356     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
 357
 358     tpm_pt->options = g_new0(TPMPassthroughOptions, 1);
 359     tpm_pt->tpm_fd = -1;
 360     tpm_pt->cancel_fd = -1;
 361 }
 362
 363 static void tpm_passthrough_inst_finalize(Object *obj)
 364 {
 365     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
 366
 367     tpm_passthrough_cancel_cmd(TPM_BACKEND(obj));
 368
 369     if (tpm_pt->tpm_fd >= 0) {
 370         qemu_close(tpm_pt->tpm_fd);
 371     }
 372     if (tpm_pt->cancel_fd >= 0) {
 373         qemu_close(tpm_pt->cancel_fd);
 374     }
 375     qapi_free_TPMPassthroughOptions(tpm_pt->options);
 376 }
 377
 378 static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
 379 {
 380     TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);
 381
 382     tbc->type = TPM_TYPE_PASSTHROUGH;
 383     tbc->opts = tpm_passthrough_cmdline_opts;
 384     tbc->desc = "Passthrough TPM backend driver";
 385     tbc->create = tpm_passthrough_create;
 386     tbc->startup_tpm = tpm_passthrough_startup_tpm;
 387     tbc->reset = tpm_passthrough_reset;
 388     tbc->cancel_cmd = tpm_passthrough_cancel_cmd;
 389     tbc->get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag;
 390     tbc->reset_tpm_established_flag =
 391         tpm_passthrough_reset_tpm_established_flag;
 392     tbc->get_tpm_version = tpm_passthrough_get_tpm_version;
 393     tbc->get_buffer_size = tpm_passthrough_get_buffer_size;
 394     tbc->get_tpm_options = tpm_passthrough_get_tpm_options;
 395     tbc->handle_request = tpm_passthrough_handle_request;
 396 }
 397
 398 static const TypeInfo tpm_passthrough_info = {
 399     .name = TYPE_TPM_PASSTHROUGH,
 400     .parent = TYPE_TPM_BACKEND,
 401     .instance_size = sizeof(TPMPassthruState),
 402     .class_init = tpm_passthrough_class_init,
 403     .instance_init = tpm_passthrough_inst_init,
 404     .instance_finalize = tpm_passthrough_inst_finalize,
 405 };
 406
 407 static void tpm_passthrough_register(void)
 408 {
 409     type_register_static(&tpm_passthrough_info);
 410 }
 411
 412 type_init(tpm_passthrough_register)