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