blob: a495fe07f4a8c731f27ed6f58e5b60f0dee9533b [file] [log] [blame]
/*
* 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/sockets.h"
#include "sysemu/tpm_backend.h"
#include "tpm_int.h"
#include "hw/hw.h"
#include "qapi/clone-visitor.h"
#include "tpm_util.h"
#define DEBUG_TPM 0
#define DPRINTF(fmt, ...) do { \
if (DEBUG_TPM) { \
fprintf(stderr, fmt, ## __VA_ARGS__); \
} \
} while (0)
#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);
DPRINTF("tpm_passthrough: processing command %p\n", 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)
{
DPRINTF("tpm_passthrough: CALL TO TPM_RESET!\n");
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)