hw/tpm/tpm_passthrough.c - qemu - Git at Google

 /*
  *  passthrough TPM driver
  *
  *  Copyright (c) 2010 - 2013 IBM Corporation
  *  Authors:
  *    Stefan Berger <stefanb@us.ibm.com>
  *
  *  Copyright (C) 2011 IAIK, Graz University of Technology
  *    Author: Andreas Niederl
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this library; if not, see <http://www.gnu.org/licenses/>
  */

 #include "qemu/osdep.h"
 #include "qemu-common.h"
 #include "qemu/error-report.h"
 #include "qemu/module.h"
 #include "qemu/sockets.h"
 #include "sysemu/tpm_backend.h"
 #include "tpm_int.h"
 #include "qapi/clone-visitor.h"
 #include "qapi/qapi-visit-tpm.h"
 #include "tpm_util.h"
 #include "trace.h"

 #define TYPE_TPM_PASSTHROUGH "tpm-passthrough"
 #define TPM_PASSTHROUGH(obj) \
     OBJECT_CHECK(TPMPassthruState, (obj), TYPE_TPM_PASSTHROUGH)

 /* data structures */
 struct TPMPassthruState {
     TPMBackend parent;

     TPMPassthroughOptions *options;
     const char *tpm_dev;
     int tpm_fd;
     bool tpm_executing;
     bool tpm_op_canceled;
     int cancel_fd;

     TPMVersion tpm_version;
     size_t tpm_buffersize;
 };

 typedef struct TPMPassthruState TPMPassthruState;

 #define TPM_PASSTHROUGH_DEFAULT_DEVICE "/dev/tpm0"

 /* functions */

 static void tpm_passthrough_cancel_cmd(TPMBackend *tb);

 static int tpm_passthrough_unix_read(int fd, uint8_t *buf, uint32_t len)
 {
     int ret;
  reread:
     ret = read(fd, buf, len);
     if (ret < 0) {
         if (errno != EINTR && errno != EAGAIN) {
             return -1;
         }
         goto reread;
     }
     return ret;
 }

 static void tpm_passthrough_unix_tx_bufs(TPMPassthruState *tpm_pt,
                                          const uint8_t *in, uint32_t in_len,
                                          uint8_t *out, uint32_t out_len,
                                          bool *selftest_done, Error **errp)
 {
     ssize_t ret;
     bool is_selftest;

     /* FIXME: protect shared variables or use other sync mechanism */
     tpm_pt->tpm_op_canceled = false;
     tpm_pt->tpm_executing = true;
     *selftest_done = false;

     is_selftest = tpm_util_is_selftest(in, in_len);

     ret = qemu_write_full(tpm_pt->tpm_fd, in, in_len);
     if (ret != in_len) {
         if (!tpm_pt->tpm_op_canceled || errno != ECANCELED) {
             error_setg_errno(errp, errno, "tpm_passthrough: error while "
                              "transmitting data to TPM");
         }
         goto err_exit;
     }

     tpm_pt->tpm_executing = false;

     ret = tpm_passthrough_unix_read(tpm_pt->tpm_fd, out, out_len);
     if (ret < 0) {
         if (!tpm_pt->tpm_op_canceled || errno != ECANCELED) {
             error_setg_errno(errp, errno, "tpm_passthrough: error while "
                              "reading data from TPM");
         }
     } else if (ret < sizeof(struct tpm_resp_hdr) ||
                tpm_cmd_get_size(out) != ret) {
         ret = -1;
         error_setg_errno(errp, errno, "tpm_passthrough: received invalid "
                      "response packet from TPM");
     }

     if (is_selftest && (ret >= sizeof(struct tpm_resp_hdr))) {
         *selftest_done = tpm_cmd_get_errcode(out) == 0;
     }

 err_exit:
     if (ret < 0) {
         tpm_util_write_fatal_error_response(out, out_len);
     }

     tpm_pt->tpm_executing = false;
 }

 static void tpm_passthrough_handle_request(TPMBackend *tb, TPMBackendCmd *cmd,
                                            Error **errp)
 {
     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

     trace_tpm_passthrough_handle_request(cmd);

     tpm_passthrough_unix_tx_bufs(tpm_pt, cmd->in, cmd->in_len,
                                  cmd->out, cmd->out_len, &cmd->selftest_done,
                                  errp);
 }

 static void tpm_passthrough_reset(TPMBackend *tb)
 {
     trace_tpm_passthrough_reset();

     tpm_passthrough_cancel_cmd(tb);
 }

 static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)
 {
     return false;
 }

 static int tpm_passthrough_reset_tpm_established_flag(TPMBackend *tb,
                                                       uint8_t locty)
 {
     /* only a TPM 2.0 will support this */
     return 0;
 }

 static void tpm_passthrough_cancel_cmd(TPMBackend *tb)
 {
     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
     int n;

     /*
      * As of Linux 3.7 the tpm_tis driver does not properly cancel
      * commands on all TPM manufacturers' TPMs.
      * Only cancel if we're busy so we don't cancel someone else's
      * command, e.g., a command executed on the host.
      */
     if (tpm_pt->tpm_executing) {
         if (tpm_pt->cancel_fd >= 0) {
             tpm_pt->tpm_op_canceled = true;
             n = write(tpm_pt->cancel_fd, "-", 1);
             if (n != 1) {
                 error_report("Canceling TPM command failed: %s",
                              strerror(errno));
             }
         } else {
             error_report("Cannot cancel TPM command due to missing "
                          "TPM sysfs cancel entry");
         }
     }
 }

 static TPMVersion tpm_passthrough_get_tpm_version(TPMBackend *tb)
 {
     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

     return tpm_pt->tpm_version;
 }

 static size_t tpm_passthrough_get_buffer_size(TPMBackend *tb)
 {
     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
     int ret;

     ret = tpm_util_get_buffer_size(tpm_pt->tpm_fd, tpm_pt->tpm_version,
                                    &tpm_pt->tpm_buffersize);
     if (ret < 0) {
         tpm_pt->tpm_buffersize = 4096;
     }
     return tpm_pt->tpm_buffersize;
 }

 /*
  * Unless path or file descriptor set has been provided by user,
  * determine the sysfs cancel file following kernel documentation
  * in Documentation/ABI/stable/sysfs-class-tpm.
  * From /dev/tpm0 create /sys/class/tpm/tpm0/device/cancel
  * before 4.0: /sys/class/misc/tpm0/device/cancel
  */
 static int tpm_passthrough_open_sysfs_cancel(TPMPassthruState *tpm_pt)
 {
     int fd = -1;
     char *dev;
     char path[PATH_MAX];

     if (tpm_pt->options->cancel_path) {
         fd = qemu_open(tpm_pt->options->cancel_path, O_WRONLY);
         if (fd < 0) {
             error_report("tpm_passthrough: Could not open TPM cancel path: %s",
                          strerror(errno));
         }
         return fd;
     }

     dev = strrchr(tpm_pt->tpm_dev, '/');
     if (!dev) {
         error_report("tpm_passthrough: Bad TPM device path %s",
                      tpm_pt->tpm_dev);
         return -1;
     }

     dev++;
     if (snprintf(path, sizeof(path), "/sys/class/tpm/%s/device/cancel",
                  dev) < sizeof(path)) {
         fd = qemu_open(path, O_WRONLY);
         if (fd < 0) {
             if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
                          dev) < sizeof(path)) {
                 fd = qemu_open(path, O_WRONLY);
             }
         }
     }

     if (fd < 0) {
         error_report("tpm_passthrough: Could not guess TPM cancel path");
     } else {
         tpm_pt->options->cancel_path = g_strdup(path);
     }

     return fd;
 }

 static int
 tpm_passthrough_handle_device_opts(TPMPassthruState *tpm_pt, QemuOpts *opts)
 {
     const char *value;

     value = qemu_opt_get(opts, "cancel-path");
     if (value) {
         tpm_pt->options->cancel_path = g_strdup(value);
         tpm_pt->options->has_cancel_path = true;
     }

     value = qemu_opt_get(opts, "path");
     if (value) {
         tpm_pt->options->has_path = true;
         tpm_pt->options->path = g_strdup(value);
     }

     tpm_pt->tpm_dev = value ? value : TPM_PASSTHROUGH_DEFAULT_DEVICE;
     tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
     if (tpm_pt->tpm_fd < 0) {
         error_report("Cannot access TPM device using '%s': %s",
                      tpm_pt->tpm_dev, strerror(errno));
         return -1;
     }

     if (tpm_util_test_tpmdev(tpm_pt->tpm_fd, &tpm_pt->tpm_version)) {
         error_report("'%s' is not a TPM device.",
                      tpm_pt->tpm_dev);
         return -1;
     }

     tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tpm_pt);
     if (tpm_pt->cancel_fd < 0) {
         return -1;
     }

     return 0;
 }

 static TPMBackend *tpm_passthrough_create(QemuOpts *opts)
 {
     Object *obj = object_new(TYPE_TPM_PASSTHROUGH);

     if (tpm_passthrough_handle_device_opts(TPM_PASSTHROUGH(obj), opts)) {
         object_unref(obj);
         return NULL;
     }

     return TPM_BACKEND(obj);
 }

 static int tpm_passthrough_startup_tpm(TPMBackend *tb, size_t buffersize)
 {
     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

     if (buffersize && buffersize < tpm_pt->tpm_buffersize) {
         error_report("Requested buffer size of %zu is smaller than host TPM's "
                      "fixed buffer size of %zu",
                      buffersize, tpm_pt->tpm_buffersize);
         return -1;
     }

     return 0;
 }

 static TpmTypeOptions *tpm_passthrough_get_tpm_options(TPMBackend *tb)
 {
     TpmTypeOptions *options = g_new0(TpmTypeOptions, 1);

     options->type = TPM_TYPE_OPTIONS_KIND_PASSTHROUGH;
     options->u.passthrough.data = QAPI_CLONE(TPMPassthroughOptions,
                                              TPM_PASSTHROUGH(tb)->options);

     return options;
 }

 static const QemuOptDesc tpm_passthrough_cmdline_opts[] = {
     TPM_STANDARD_CMDLINE_OPTS,
     {
         .name = "cancel-path",
         .type = QEMU_OPT_STRING,
         .help = "Sysfs file entry for canceling TPM commands",
     },
     {
         .name = "path",
         .type = QEMU_OPT_STRING,
         .help = "Path to TPM device on the host",
     },
     { /* end of list */ },
 };

 static void tpm_passthrough_inst_init(Object *obj)
 {
     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);

     tpm_pt->options = g_new0(TPMPassthroughOptions, 1);
     tpm_pt->tpm_fd = -1;
     tpm_pt->cancel_fd = -1;
 }

 static void tpm_passthrough_inst_finalize(Object *obj)
 {
     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);

     tpm_passthrough_cancel_cmd(TPM_BACKEND(obj));

     if (tpm_pt->tpm_fd >= 0) {
         qemu_close(tpm_pt->tpm_fd);
     }
     if (tpm_pt->cancel_fd >= 0) {
         qemu_close(tpm_pt->cancel_fd);
     }
     qapi_free_TPMPassthroughOptions(tpm_pt->options);
 }

 static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
 {
     TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);

     tbc->type = TPM_TYPE_PASSTHROUGH;
     tbc->opts = tpm_passthrough_cmdline_opts;
     tbc->desc = "Passthrough TPM backend driver";
     tbc->create = tpm_passthrough_create;
     tbc->startup_tpm = tpm_passthrough_startup_tpm;
     tbc->reset = tpm_passthrough_reset;
     tbc->cancel_cmd = tpm_passthrough_cancel_cmd;
     tbc->get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag;
     tbc->reset_tpm_established_flag =
         tpm_passthrough_reset_tpm_established_flag;
     tbc->get_tpm_version = tpm_passthrough_get_tpm_version;
     tbc->get_buffer_size = tpm_passthrough_get_buffer_size;
     tbc->get_tpm_options = tpm_passthrough_get_tpm_options;
     tbc->handle_request = tpm_passthrough_handle_request;
 }

 static const TypeInfo tpm_passthrough_info = {
     .name = TYPE_TPM_PASSTHROUGH,
     .parent = TYPE_TPM_BACKEND,
     .instance_size = sizeof(TPMPassthruState),
     .class_init = tpm_passthrough_class_init,
     .instance_init = tpm_passthrough_inst_init,
     .instance_finalize = tpm_passthrough_inst_finalize,
 };

 static void tpm_passthrough_register(void)
 {
     type_register_static(&tpm_passthrough_info);
 }

 type_init(tpm_passthrough_register)
	/*
	* passthrough TPM driver
	*
	* Copyright (c) 2010 - 2013 IBM Corporation
	* Authors:
	* Stefan Berger <stefanb@us.ibm.com>
	*
	* Copyright (C) 2011 IAIK, Graz University of Technology
	* Author: Andreas Niederl
	*
	* This library is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2 of the License, or (at your option) any later version.
	*
	* This library is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with this library; if not, see <http://www.gnu.org/licenses/>
	*/

	#include "qemu/osdep.h"
	#include "qemu-common.h"
	#include "qemu/error-report.h"
	#include "qemu/module.h"
	#include "qemu/sockets.h"
	#include "sysemu/tpm_backend.h"
	#include "tpm_int.h"
	#include "qapi/clone-visitor.h"
	#include "qapi/qapi-visit-tpm.h"
	#include "tpm_util.h"
	#include "trace.h"

	#define TYPE_TPM_PASSTHROUGH "tpm-passthrough"
	#define TPM_PASSTHROUGH(obj) \
	OBJECT_CHECK(TPMPassthruState, (obj), TYPE_TPM_PASSTHROUGH)

	/* data structures */
	struct TPMPassthruState {
	TPMBackend parent;

	TPMPassthroughOptions *options;
	const char *tpm_dev;
	int tpm_fd;
	bool tpm_executing;
	bool tpm_op_canceled;
	int cancel_fd;

	TPMVersion tpm_version;
	size_t tpm_buffersize;
	};

	typedef struct TPMPassthruState TPMPassthruState;

	#define TPM_PASSTHROUGH_DEFAULT_DEVICE "/dev/tpm0"

	/* functions */

	static void tpm_passthrough_cancel_cmd(TPMBackend *tb);

	static int tpm_passthrough_unix_read(int fd, uint8_t *buf, uint32_t len)
	{
	int ret;
	reread:
	ret = read(fd, buf, len);
	if (ret < 0) {
	if (errno != EINTR && errno != EAGAIN) {
	return -1;
	}
	goto reread;
	}
	return ret;
	}

	static void tpm_passthrough_unix_tx_bufs(TPMPassthruState *tpm_pt,
	const uint8_t *in, uint32_t in_len,
	uint8_t *out, uint32_t out_len,
	bool selftest_done, Error *errp)
	{
	ssize_t ret;
	bool is_selftest;

	/* FIXME: protect shared variables or use other sync mechanism */
	tpm_pt->tpm_op_canceled = false;
	tpm_pt->tpm_executing = true;
	*selftest_done = false;

	is_selftest = tpm_util_is_selftest(in, in_len);

	ret = qemu_write_full(tpm_pt->tpm_fd, in, in_len);
	if (ret != in_len) {
	if (!tpm_pt->tpm_op_canceled \|\| errno != ECANCELED) {
	error_setg_errno(errp, errno, "tpm_passthrough: error while "
	"transmitting data to TPM");
	}
	goto err_exit;
	}

	tpm_pt->tpm_executing = false;

	ret = tpm_passthrough_unix_read(tpm_pt->tpm_fd, out, out_len);
	if (ret < 0) {
	if (!tpm_pt->tpm_op_canceled \|\| errno != ECANCELED) {
	error_setg_errno(errp, errno, "tpm_passthrough: error while "
	"reading data from TPM");
	}
	} else if (ret < sizeof(struct tpm_resp_hdr) \|\|
	tpm_cmd_get_size(out) != ret) {
	ret = -1;
	error_setg_errno(errp, errno, "tpm_passthrough: received invalid "
	"response packet from TPM");
	}

	if (is_selftest && (ret >= sizeof(struct tpm_resp_hdr))) {
	*selftest_done = tpm_cmd_get_errcode(out) == 0;
	}

	err_exit:
	if (ret < 0) {
	tpm_util_write_fatal_error_response(out, out_len);
	}

	tpm_pt->tpm_executing = false;
	}

	static void tpm_passthrough_handle_request(TPMBackend tb, TPMBackendCmd cmd,
	Error **errp)
	{
	TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

	trace_tpm_passthrough_handle_request(cmd);

	tpm_passthrough_unix_tx_bufs(tpm_pt, cmd->in, cmd->in_len,
	cmd->out, cmd->out_len, &cmd->selftest_done,
	errp);
	}

	static void tpm_passthrough_reset(TPMBackend *tb)
	{
	trace_tpm_passthrough_reset();

	tpm_passthrough_cancel_cmd(tb);
	}

	static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)
	{
	return false;
	}

	static int tpm_passthrough_reset_tpm_established_flag(TPMBackend *tb,
	uint8_t locty)
	{
	/* only a TPM 2.0 will support this */
	return 0;
	}

	static void tpm_passthrough_cancel_cmd(TPMBackend *tb)
	{
	TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
	int n;

	/*
	* As of Linux 3.7 the tpm_tis driver does not properly cancel
	* commands on all TPM manufacturers' TPMs.
	* Only cancel if we're busy so we don't cancel someone else's
	* command, e.g., a command executed on the host.
	*/
	if (tpm_pt->tpm_executing) {
	if (tpm_pt->cancel_fd >= 0) {
	tpm_pt->tpm_op_canceled = true;
	n = write(tpm_pt->cancel_fd, "-", 1);
	if (n != 1) {
	error_report("Canceling TPM command failed: %s",
	strerror(errno));
	}
	} else {
	error_report("Cannot cancel TPM command due to missing "
	"TPM sysfs cancel entry");
	}
	}
	}

	static TPMVersion tpm_passthrough_get_tpm_version(TPMBackend *tb)
	{
	TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

	return tpm_pt->tpm_version;
	}

	static size_t tpm_passthrough_get_buffer_size(TPMBackend *tb)
	{
	TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
	int ret;

	ret = tpm_util_get_buffer_size(tpm_pt->tpm_fd, tpm_pt->tpm_version,
	&tpm_pt->tpm_buffersize);
	if (ret < 0) {
	tpm_pt->tpm_buffersize = 4096;
	}
	return tpm_pt->tpm_buffersize;
	}

	/*
	* Unless path or file descriptor set has been provided by user,
	* determine the sysfs cancel file following kernel documentation
	* in Documentation/ABI/stable/sysfs-class-tpm.
	* From /dev/tpm0 create /sys/class/tpm/tpm0/device/cancel
	* before 4.0: /sys/class/misc/tpm0/device/cancel
	*/
	static int tpm_passthrough_open_sysfs_cancel(TPMPassthruState *tpm_pt)
	{
	int fd = -1;
	char *dev;
	char path[PATH_MAX];

	if (tpm_pt->options->cancel_path) {
	fd = qemu_open(tpm_pt->options->cancel_path, O_WRONLY);
	if (fd < 0) {
	error_report("tpm_passthrough: Could not open TPM cancel path: %s",
	strerror(errno));
	}
	return fd;
	}

	dev = strrchr(tpm_pt->tpm_dev, '/');
	if (!dev) {
	error_report("tpm_passthrough: Bad TPM device path %s",
	tpm_pt->tpm_dev);
	return -1;
	}

	dev++;
	if (snprintf(path, sizeof(path), "/sys/class/tpm/%s/device/cancel",
	dev) < sizeof(path)) {
	fd = qemu_open(path, O_WRONLY);
	if (fd < 0) {
	if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
	dev) < sizeof(path)) {
	fd = qemu_open(path, O_WRONLY);
	}
	}
	}

	if (fd < 0) {
	error_report("tpm_passthrough: Could not guess TPM cancel path");
	} else {
	tpm_pt->options->cancel_path = g_strdup(path);
	}

	return fd;
	}

	static int
	tpm_passthrough_handle_device_opts(TPMPassthruState tpm_pt, QemuOpts opts)
	{
	const char *value;

	value = qemu_opt_get(opts, "cancel-path");
	if (value) {
	tpm_pt->options->cancel_path = g_strdup(value);
	tpm_pt->options->has_cancel_path = true;
	}

	value = qemu_opt_get(opts, "path");
	if (value) {
	tpm_pt->options->has_path = true;
	tpm_pt->options->path = g_strdup(value);
	}

	tpm_pt->tpm_dev = value ? value : TPM_PASSTHROUGH_DEFAULT_DEVICE;
	tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
	if (tpm_pt->tpm_fd < 0) {
	error_report("Cannot access TPM device using '%s': %s",
	tpm_pt->tpm_dev, strerror(errno));
	return -1;
	}

	if (tpm_util_test_tpmdev(tpm_pt->tpm_fd, &tpm_pt->tpm_version)) {
	error_report("'%s' is not a TPM device.",
	tpm_pt->tpm_dev);
	return -1;
	}

	tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tpm_pt);
	if (tpm_pt->cancel_fd < 0) {
	return -1;
	}

	return 0;
	}

	static TPMBackend tpm_passthrough_create(QemuOpts opts)
	{
	Object *obj = object_new(TYPE_TPM_PASSTHROUGH);

	if (tpm_passthrough_handle_device_opts(TPM_PASSTHROUGH(obj), opts)) {
	object_unref(obj);
	return NULL;
	}

	return TPM_BACKEND(obj);
	}

	static int tpm_passthrough_startup_tpm(TPMBackend *tb, size_t buffersize)
	{
	TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

	if (buffersize && buffersize < tpm_pt->tpm_buffersize) {
	error_report("Requested buffer size of %zu is smaller than host TPM's "
	"fixed buffer size of %zu",
	buffersize, tpm_pt->tpm_buffersize);
	return -1;
	}

	return 0;
	}

	static TpmTypeOptions tpm_passthrough_get_tpm_options(TPMBackend tb)
	{
	TpmTypeOptions *options = g_new0(TpmTypeOptions, 1);

	options->type = TPM_TYPE_OPTIONS_KIND_PASSTHROUGH;
	options->u.passthrough.data = QAPI_CLONE(TPMPassthroughOptions,
	TPM_PASSTHROUGH(tb)->options);

	return options;
	}

	static const QemuOptDesc tpm_passthrough_cmdline_opts[] = {
	TPM_STANDARD_CMDLINE_OPTS,
	{
	.name = "cancel-path",
	.type = QEMU_OPT_STRING,
	.help = "Sysfs file entry for canceling TPM commands",
	},
	{
	.name = "path",
	.type = QEMU_OPT_STRING,
	.help = "Path to TPM device on the host",
	},
	{ /* end of list */ },
	};

	static void tpm_passthrough_inst_init(Object *obj)
	{
	TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);

	tpm_pt->options = g_new0(TPMPassthroughOptions, 1);
	tpm_pt->tpm_fd = -1;
	tpm_pt->cancel_fd = -1;
	}

	static void tpm_passthrough_inst_finalize(Object *obj)
	{
	TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);

	tpm_passthrough_cancel_cmd(TPM_BACKEND(obj));

	if (tpm_pt->tpm_fd >= 0) {
	qemu_close(tpm_pt->tpm_fd);
	}
	if (tpm_pt->cancel_fd >= 0) {
	qemu_close(tpm_pt->cancel_fd);
	}
	qapi_free_TPMPassthroughOptions(tpm_pt->options);
	}

	static void tpm_passthrough_class_init(ObjectClass klass, void data)
	{
	TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);

	tbc->type = TPM_TYPE_PASSTHROUGH;
	tbc->opts = tpm_passthrough_cmdline_opts;
	tbc->desc = "Passthrough TPM backend driver";
	tbc->create = tpm_passthrough_create;
	tbc->startup_tpm = tpm_passthrough_startup_tpm;
	tbc->reset = tpm_passthrough_reset;
	tbc->cancel_cmd = tpm_passthrough_cancel_cmd;
	tbc->get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag;
	tbc->reset_tpm_established_flag =
	tpm_passthrough_reset_tpm_established_flag;
	tbc->get_tpm_version = tpm_passthrough_get_tpm_version;
	tbc->get_buffer_size = tpm_passthrough_get_buffer_size;
	tbc->get_tpm_options = tpm_passthrough_get_tpm_options;
	tbc->handle_request = tpm_passthrough_handle_request;
	}

	static const TypeInfo tpm_passthrough_info = {
	.name = TYPE_TPM_PASSTHROUGH,
	.parent = TYPE_TPM_BACKEND,
	.instance_size = sizeof(TPMPassthruState),
	.class_init = tpm_passthrough_class_init,
	.instance_init = tpm_passthrough_inst_init,
	.instance_finalize = tpm_passthrough_inst_finalize,
	};

	static void tpm_passthrough_register(void)
	{
	type_register_static(&tpm_passthrough_info);
	}

	type_init(tpm_passthrough_register)