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 "hw/i386/pc.h"
  33 #include "qapi/clone-visitor.h"
  34 #include "tpm_util.h"
  35
  36 #define DEBUG_TPM 0
  37
  38 #define DPRINTF(fmt, ...) do { \
  39     if (DEBUG_TPM) { \
  40         fprintf(stderr, fmt, ## __VA_ARGS__); \
  41     } \
  42 } while (0);
  43
  44 #define TYPE_TPM_PASSTHROUGH "tpm-passthrough"
  45 #define TPM_PASSTHROUGH(obj) \
  46     OBJECT_CHECK(TPMPassthruState, (obj), TYPE_TPM_PASSTHROUGH)
  47
  48 /* data structures */
  49 struct TPMPassthruState {
  50     TPMBackend parent;
  51
  52     TPMPassthroughOptions *options;
  53     const char *tpm_dev;
  54     int tpm_fd;
  55     bool tpm_executing;
  56     bool tpm_op_canceled;
  57     int cancel_fd;
  58
  59     TPMVersion tpm_version;
  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     const struct tpm_resp_hdr *hdr;
  91
  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                be32_to_cpu(((struct tpm_resp_hdr *)out)->len) != 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         hdr = (struct tpm_resp_hdr *)out;
 126         *selftest_done = (be32_to_cpu(hdr->errcode) == 0);
 127     }
 128
 129 err_exit:
 130     if (ret < 0) {
 131         tpm_util_write_fatal_error_response(out, out_len);
 132     }
 133
 134     tpm_pt->tpm_executing = false;
 135
 136     return ret;
 137 }
 138
 139 static void tpm_passthrough_handle_request(TPMBackend *tb, TPMBackendCmd *cmd)
 140 {
 141     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 142
 143     DPRINTF("tpm_passthrough: processing command %p\n", cmd);
 144
 145     tpm_passthrough_unix_tx_bufs(tpm_pt, cmd->in, cmd->in_len,
 146                                  cmd->out, cmd->out_len, &cmd->selftest_done);
 147 }
 148
 149 static void tpm_passthrough_reset(TPMBackend *tb)
 150 {
 151     DPRINTF("tpm_passthrough: CALL TO TPM_RESET!\n");
 152
 153     tpm_passthrough_cancel_cmd(tb);
 154 }
 155
 156 static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)
 157 {
 158     return false;
 159 }
 160
 161 static int tpm_passthrough_reset_tpm_established_flag(TPMBackend *tb,
 162                                                       uint8_t locty)
 163 {
 164     /* only a TPM 2.0 will support this */
 165     return 0;
 166 }
 167
 168 static void tpm_passthrough_cancel_cmd(TPMBackend *tb)
 169 {
 170     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 171     int n;
 172
 173     /*
 174      * As of Linux 3.7 the tpm_tis driver does not properly cancel
 175      * commands on all TPM manufacturers' TPMs.
 176      * Only cancel if we're busy so we don't cancel someone else's
 177      * command, e.g., a command executed on the host.
 178      */
 179     if (tpm_pt->tpm_executing) {
 180         if (tpm_pt->cancel_fd >= 0) {
 181             n = write(tpm_pt->cancel_fd, "-", 1);
 182             if (n != 1) {
 183                 error_report("Canceling TPM command failed: %s",
 184                              strerror(errno));
 185             } else {
 186                 tpm_pt->tpm_op_canceled = true;
 187             }
 188         } else {
 189             error_report("Cannot cancel TPM command due to missing "
 190                          "TPM sysfs cancel entry");
 191         }
 192     }
 193 }
 194
 195 static TPMVersion tpm_passthrough_get_tpm_version(TPMBackend *tb)
 196 {
 197     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 198
 199     return tpm_pt->tpm_version;
 200 }
 201
 202 /*
 203  * Unless path or file descriptor set has been provided by user,
 204  * determine the sysfs cancel file following kernel documentation
 205  * in Documentation/ABI/stable/sysfs-class-tpm.
 206  * From /dev/tpm0 create /sys/class/misc/tpm0/device/cancel
 207  */
 208 static int tpm_passthrough_open_sysfs_cancel(TPMPassthruState *tpm_pt)
 209 {
 210     int fd = -1;
 211     char *dev;
 212     char path[PATH_MAX];
 213
 214     if (tpm_pt->options->cancel_path) {
 215         fd = qemu_open(tpm_pt->options->cancel_path, O_WRONLY);
 216         if (fd < 0) {
 217             error_report("Could not open TPM cancel path : %s",
 218                          strerror(errno));
 219         }
 220         return fd;
 221     }
 222
 223     dev = strrchr(tpm_pt->tpm_dev, '/');
 224     if (dev) {
 225         dev++;
 226         if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
 227                      dev) < sizeof(path)) {
 228             fd = qemu_open(path, O_WRONLY);
 229             if (fd < 0) {
 230                 error_report("tpm_passthrough: Could not open TPM cancel "
 231                              "path %s : %s", path, strerror(errno));
 232             }
 233         }
 234     } else {
 235        error_report("tpm_passthrough: Bad TPM device path %s",
 236                     tpm_pt->tpm_dev);
 237     }
 238
 239     return fd;
 240 }
 241
 242 static int
 243 tpm_passthrough_handle_device_opts(TPMPassthruState *tpm_pt, QemuOpts *opts)
 244 {
 245     const char *value;
 246
 247     value = qemu_opt_get(opts, "cancel-path");
 248     if (value) {
 249         tpm_pt->options->cancel_path = g_strdup(value);
 250         tpm_pt->options->has_cancel_path = true;
 251     }
 252
 253     value = qemu_opt_get(opts, "path");
 254     if (value) {
 255         tpm_pt->options->has_path = true;
 256         tpm_pt->options->path = g_strdup(value);
 257     }
 258
 259     tpm_pt->tpm_dev = value ? value : TPM_PASSTHROUGH_DEFAULT_DEVICE;
 260     tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
 261     if (tpm_pt->tpm_fd < 0) {
 262         error_report("Cannot access TPM device using '%s': %s",
 263                      tpm_pt->tpm_dev, strerror(errno));
 264         goto err_free_parameters;
 265     }
 266
 267     if (tpm_util_test_tpmdev(tpm_pt->tpm_fd, &tpm_pt->tpm_version)) {
 268         error_report("'%s' is not a TPM device.",
 269                      tpm_pt->tpm_dev);
 270         goto err_close_tpmdev;
 271     }
 272
 273     return 0;
 274
 275  err_close_tpmdev:
 276     qemu_close(tpm_pt->tpm_fd);
 277     tpm_pt->tpm_fd = -1;
 278
 279  err_free_parameters:
 280     qapi_free_TPMPassthroughOptions(tpm_pt->options);
 281     tpm_pt->options = NULL;
 282     tpm_pt->tpm_dev = NULL;
 283
 284     return 1;
 285 }
 286
 287 static TPMBackend *tpm_passthrough_create(QemuOpts *opts)
 288 {
 289     Object *obj = object_new(TYPE_TPM_PASSTHROUGH);
 290     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
 291
 292     if (tpm_passthrough_handle_device_opts(tpm_pt, opts)) {
 293         goto err_exit;
 294     }
 295
 296     tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tpm_pt);
 297     if (tpm_pt->cancel_fd < 0) {
 298         goto err_exit;
 299     }
 300
 301     return TPM_BACKEND(obj);
 302
 303 err_exit:
 304     object_unref(obj);
 305
 306     return NULL;
 307 }
 308
 309 static TpmTypeOptions *tpm_passthrough_get_tpm_options(TPMBackend *tb)
 310 {
 311     TpmTypeOptions *options = g_new0(TpmTypeOptions, 1);
 312
 313     options->type = TPM_TYPE_OPTIONS_KIND_PASSTHROUGH;
 314     options->u.passthrough.data = QAPI_CLONE(TPMPassthroughOptions,
 315                                              TPM_PASSTHROUGH(tb)->options);
 316
 317     return options;
 318 }
 319
 320 static const QemuOptDesc tpm_passthrough_cmdline_opts[] = {
 321     TPM_STANDARD_CMDLINE_OPTS,
 322     {
 323         .name = "cancel-path",
 324         .type = QEMU_OPT_STRING,
 325         .help = "Sysfs file entry for canceling TPM commands",
 326     },
 327     {
 328         .name = "path",
 329         .type = QEMU_OPT_STRING,
 330         .help = "Path to TPM device on the host",
 331     },
 332     { /* end of list */ },
 333 };
 334
 335 static void tpm_passthrough_inst_init(Object *obj)
 336 {
 337     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
 338
 339     tpm_pt->options = g_new0(TPMPassthroughOptions, 1);
 340     tpm_pt->tpm_fd = -1;
 341     tpm_pt->cancel_fd = -1;
 342 }
 343
 344 static void tpm_passthrough_inst_finalize(Object *obj)
 345 {
 346     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
 347
 348     tpm_passthrough_cancel_cmd(TPM_BACKEND(obj));
 349
 350     if (tpm_pt->tpm_fd >= 0) {
 351         qemu_close(tpm_pt->tpm_fd);
 352     }
 353     if (tpm_pt->cancel_fd >= 0) {
 354         qemu_close(tpm_pt->cancel_fd);
 355     }
 356     qapi_free_TPMPassthroughOptions(tpm_pt->options);
 357 }
 358
 359 static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
 360 {
 361     TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);
 362
 363     tbc->type = TPM_TYPE_PASSTHROUGH;
 364     tbc->opts = tpm_passthrough_cmdline_opts;
 365     tbc->desc = "Passthrough TPM backend driver";
 366     tbc->create = tpm_passthrough_create;
 367     tbc->reset = tpm_passthrough_reset;
 368     tbc->cancel_cmd = tpm_passthrough_cancel_cmd;
 369     tbc->get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag;
 370     tbc->reset_tpm_established_flag =
 371         tpm_passthrough_reset_tpm_established_flag;
 372     tbc->get_tpm_version = tpm_passthrough_get_tpm_version;
 373     tbc->get_tpm_options = tpm_passthrough_get_tpm_options;
 374     tbc->handle_request = tpm_passthrough_handle_request;
 375 }
 376
 377 static const TypeInfo tpm_passthrough_info = {
 378     .name = TYPE_TPM_PASSTHROUGH,
 379     .parent = TYPE_TPM_BACKEND,
 380     .instance_size = sizeof(TPMPassthruState),
 381     .class_init = tpm_passthrough_class_init,
 382     .instance_init = tpm_passthrough_inst_init,
 383     .instance_finalize = tpm_passthrough_inst_finalize,
 384 };
 385
 386 static void tpm_passthrough_register(void)
 387 {
 388     type_register_static(&tpm_passthrough_info);
 389 }
 390
 391 type_init(tpm_passthrough_register)