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