qemu/backends/tpm/tpm_passthrough.c
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   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 */
  42struct 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
  56typedef struct TPMPassthruState TPMPassthruState;
  57
  58#define TPM_PASSTHROUGH_DEFAULT_DEVICE "/dev/tpm0"
  59
  60/* functions */
  61
  62static void tpm_passthrough_cancel_cmd(TPMBackend *tb);
  63
  64static 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
  78static 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
 121err_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
 129static 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
 141static void tpm_passthrough_reset(TPMBackend *tb)
 142{
 143    trace_tpm_passthrough_reset();
 144
 145    tpm_passthrough_cancel_cmd(tb);
 146}
 147
 148static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)
 149{
 150    return false;
 151}
 152
 153static 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
 160static 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
 186static 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
 193static 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 */
 213static 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
 256static int
 257tpm_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
 295static 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
 307static 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
 321static 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
 332static 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
 347static 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
 356static 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
 371static 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
 391static 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
 400static void tpm_passthrough_register(void)
 401{
 402    type_register_static(&tpm_passthrough_info);
 403}
 404
 405type_init(tpm_passthrough_register)
 406