qemu/hw/tpm/tpm_passthrough.c

577 lines
15 KiB
C

/*
* 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 <dirent.h>
#include "qemu-common.h"
#include "qapi/error.h"
#include "qemu/sockets.h"
#include "sysemu/tpm_backend.h"
#include "tpm_int.h"
#include "hw/hw.h"
#include "hw/i386/pc.h"
#include "sysemu/tpm_backend_int.h"
#include "tpm_tis.h"
/* #define DEBUG_TPM */
#ifdef DEBUG_TPM
#define DPRINTF(fmt, ...) \
do { fprintf(stderr, fmt, ## __VA_ARGS__); } while (0)
#else
#define DPRINTF(fmt, ...) \
do { } while (0)
#endif
#define TYPE_TPM_PASSTHROUGH "tpm-passthrough"
#define TPM_PASSTHROUGH(obj) \
OBJECT_CHECK(TPMPassthruState, (obj), TYPE_TPM_PASSTHROUGH)
static const TPMDriverOps tpm_passthrough_driver;
/* data structures */
typedef struct TPMPassthruThreadParams {
TPMState *tpm_state;
TPMRecvDataCB *recv_data_callback;
TPMBackend *tb;
} TPMPassthruThreadParams;
struct TPMPassthruState {
TPMBackend parent;
TPMBackendThread tbt;
TPMPassthruThreadParams tpm_thread_params;
char *tpm_dev;
int tpm_fd;
bool tpm_executing;
bool tpm_op_canceled;
int cancel_fd;
bool had_startup_error;
};
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_write(int fd, const uint8_t *buf, uint32_t len)
{
return send_all(fd, buf, len);
}
static int tpm_passthrough_unix_read(int fd, uint8_t *buf, uint32_t len)
{
return recv_all(fd, buf, len, true);
}
static uint32_t tpm_passthrough_get_size_from_buffer(const uint8_t *buf)
{
struct tpm_resp_hdr *resp = (struct tpm_resp_hdr *)buf;
return be32_to_cpu(resp->len);
}
/*
* Write an error message in the given output buffer.
*/
static void tpm_write_fatal_error_response(uint8_t *out, uint32_t out_len)
{
if (out_len >= sizeof(struct tpm_resp_hdr)) {
struct tpm_resp_hdr *resp = (struct tpm_resp_hdr *)out;
resp->tag = cpu_to_be16(TPM_TAG_RSP_COMMAND);
resp->len = cpu_to_be32(sizeof(struct tpm_resp_hdr));
resp->errcode = cpu_to_be32(TPM_FAIL);
}
}
static int tpm_passthrough_unix_tx_bufs(TPMPassthruState *tpm_pt,
const uint8_t *in, uint32_t in_len,
uint8_t *out, uint32_t out_len)
{
int ret;
tpm_pt->tpm_op_canceled = false;
tpm_pt->tpm_executing = true;
ret = tpm_passthrough_unix_write(tpm_pt->tpm_fd, in, in_len);
if (ret != in_len) {
if (!tpm_pt->tpm_op_canceled ||
(tpm_pt->tpm_op_canceled && errno != ECANCELED)) {
error_report("tpm_passthrough: error while transmitting data "
"to TPM: %s (%i)\n",
strerror(errno), errno);
}
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 ||
(tpm_pt->tpm_op_canceled && errno != ECANCELED)) {
error_report("tpm_passthrough: error while reading data from "
"TPM: %s (%i)\n",
strerror(errno), errno);
}
} else if (ret < sizeof(struct tpm_resp_hdr) ||
tpm_passthrough_get_size_from_buffer(out) != ret) {
ret = -1;
error_report("tpm_passthrough: received invalid response "
"packet from TPM\n");
}
err_exit:
if (ret < 0) {
tpm_write_fatal_error_response(out, out_len);
}
tpm_pt->tpm_executing = false;
return ret;
}
static int tpm_passthrough_unix_transfer(TPMPassthruState *tpm_pt,
const TPMLocality *locty_data)
{
return tpm_passthrough_unix_tx_bufs(tpm_pt,
locty_data->w_buffer.buffer,
locty_data->w_offset,
locty_data->r_buffer.buffer,
locty_data->r_buffer.size);
}
static void tpm_passthrough_worker_thread(gpointer data,
gpointer user_data)
{
TPMPassthruThreadParams *thr_parms = user_data;
TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(thr_parms->tb);
TPMBackendCmd cmd = (TPMBackendCmd)data;
DPRINTF("tpm_passthrough: processing command type %d\n", cmd);
switch (cmd) {
case TPM_BACKEND_CMD_PROCESS_CMD:
tpm_passthrough_unix_transfer(tpm_pt,
thr_parms->tpm_state->locty_data);
thr_parms->recv_data_callback(thr_parms->tpm_state,
thr_parms->tpm_state->locty_number);
break;
case TPM_BACKEND_CMD_INIT:
case TPM_BACKEND_CMD_END:
case TPM_BACKEND_CMD_TPM_RESET:
/* nothing to do */
break;
}
}
/*
* Start the TPM (thread). If it had been started before, then terminate
* and start it again.
*/
static int tpm_passthrough_startup_tpm(TPMBackend *tb)
{
TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
/* terminate a running TPM */
tpm_backend_thread_end(&tpm_pt->tbt);
tpm_backend_thread_create(&tpm_pt->tbt,
tpm_passthrough_worker_thread,
&tpm_pt->tpm_thread_params);
return 0;
}
static void tpm_passthrough_reset(TPMBackend *tb)
{
TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
DPRINTF("tpm_passthrough: CALL TO TPM_RESET!\n");
tpm_passthrough_cancel_cmd(tb);
tpm_backend_thread_end(&tpm_pt->tbt);
tpm_pt->had_startup_error = false;
}
static int tpm_passthrough_init(TPMBackend *tb, TPMState *s,
TPMRecvDataCB *recv_data_cb)
{
TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
tpm_pt->tpm_thread_params.tpm_state = s;
tpm_pt->tpm_thread_params.recv_data_callback = recv_data_cb;
tpm_pt->tpm_thread_params.tb = tb;
return 0;
}
static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)
{
return false;
}
static bool tpm_passthrough_get_startup_error(TPMBackend *tb)
{
TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
return tpm_pt->had_startup_error;
}
static size_t tpm_passthrough_realloc_buffer(TPMSizedBuffer *sb)
{
size_t wanted_size = 4096; /* Linux tpm.c buffer size */
if (sb->size != wanted_size) {
sb->buffer = g_realloc(sb->buffer, wanted_size);
sb->size = wanted_size;
}
return sb->size;
}
static void tpm_passthrough_deliver_request(TPMBackend *tb)
{
TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
tpm_backend_thread_deliver_request(&tpm_pt->tbt);
}
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) {
n = write(tpm_pt->cancel_fd, "-", 1);
if (n != 1) {
error_report("Canceling TPM command failed: %s\n",
strerror(errno));
} else {
tpm_pt->tpm_op_canceled = true;
}
} else {
error_report("Cannot cancel TPM command due to missing "
"TPM sysfs cancel entry");
}
}
}
static const char *tpm_passthrough_create_desc(void)
{
return "Passthrough TPM backend driver";
}
/*
* A basic test of a TPM device. We expect a well formatted response header
* (error response is fine) within one second.
*/
static int tpm_passthrough_test_tpmdev(int fd)
{
struct tpm_req_hdr req = {
.tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
.len = cpu_to_be32(sizeof(req)),
.ordinal = cpu_to_be32(TPM_ORD_GetTicks),
};
struct tpm_resp_hdr *resp;
fd_set readfds;
int n;
struct timeval tv = {
.tv_sec = 1,
.tv_usec = 0,
};
unsigned char buf[1024];
n = write(fd, &req, sizeof(req));
if (n < 0) {
return errno;
}
if (n != sizeof(req)) {
return EFAULT;
}
FD_ZERO(&readfds);
FD_SET(fd, &readfds);
/* wait for a second */
n = select(fd + 1, &readfds, NULL, NULL, &tv);
if (n != 1) {
return errno;
}
n = read(fd, &buf, sizeof(buf));
if (n < sizeof(struct tpm_resp_hdr)) {
return EFAULT;
}
resp = (struct tpm_resp_hdr *)buf;
/* check the header */
if (be16_to_cpu(resp->tag) != TPM_TAG_RSP_COMMAND ||
be32_to_cpu(resp->len) != n) {
return EBADMSG;
}
return 0;
}
/*
* Check whether the given base path, e.g., /sys/class/misc/tpm0/device,
* is the sysfs directory of a TPM. A TPM sysfs directory should be uniquely
* recognizable by the file entries 'pcrs' and 'cancel'.
* Upon success 'true' is returned and the basebath buffer has '/cancel'
* appended.
*/
static bool tpm_passthrough_check_sysfs_cancel(char *basepath, size_t bufsz)
{
char path[PATH_MAX];
struct stat statbuf;
snprintf(path, sizeof(path), "%s/pcrs", basepath);
if (stat(path, &statbuf) == -1 || !S_ISREG(statbuf.st_mode)) {
return false;
}
snprintf(path, sizeof(path), "%s/cancel", basepath);
if (stat(path, &statbuf) == -1 || !S_ISREG(statbuf.st_mode)) {
return false;
}
strncpy(basepath, path, bufsz);
return true;
}
/*
* 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.
*/
static int tpm_passthrough_open_sysfs_cancel(TPMBackend *tb)
{
int fd = -1;
unsigned int idx;
DIR *pnp_dir;
char path[PATH_MAX];
struct dirent entry, *result;
int len;
if (tb->cancel_path) {
fd = qemu_open(tb->cancel_path, O_WRONLY);
if (fd < 0) {
error_report("Could not open TPM cancel path : %s",
strerror(errno));
}
return fd;
}
snprintf(path, sizeof(path), "/sys/class/misc");
pnp_dir = opendir(path);
if (pnp_dir != NULL) {
while (readdir_r(pnp_dir, &entry, &result) == 0 &&
result != NULL) {
/*
* only allow /sys/class/misc/tpm%u type of paths
*/
if (sscanf(entry.d_name, "tpm%u%n", &idx, &len) < 1 ||
len <= strlen("tpm") ||
len != strlen(entry.d_name)) {
continue;
}
snprintf(path, sizeof(path), "/sys/class/misc/%s/device",
entry.d_name);
if (!tpm_passthrough_check_sysfs_cancel(path, sizeof(path))) {
continue;
}
fd = qemu_open(path, O_WRONLY);
break;
}
closedir(pnp_dir);
}
if (fd >= 0) {
tb->cancel_path = g_strdup(path);
}
return fd;
}
static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)
{
TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
const char *value;
value = qemu_opt_get(opts, "cancel-path");
if (value) {
tb->cancel_path = g_strdup(value);
}
value = qemu_opt_get(opts, "path");
if (!value) {
value = TPM_PASSTHROUGH_DEFAULT_DEVICE;
}
tpm_pt->tpm_dev = g_strdup(value);
tb->path = g_strdup(tpm_pt->tpm_dev);
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\n",
tpm_pt->tpm_dev, strerror(errno));
goto err_free_parameters;
}
if (tpm_passthrough_test_tpmdev(tpm_pt->tpm_fd)) {
error_report("'%s' is not a TPM device.\n",
tpm_pt->tpm_dev);
goto err_close_tpmdev;
}
return 0;
err_close_tpmdev:
qemu_close(tpm_pt->tpm_fd);
tpm_pt->tpm_fd = -1;
err_free_parameters:
g_free(tb->path);
tb->path = NULL;
g_free(tpm_pt->tpm_dev);
tpm_pt->tpm_dev = NULL;
return 1;
}
static TPMBackend *tpm_passthrough_create(QemuOpts *opts, const char *id)
{
Object *obj = object_new(TYPE_TPM_PASSTHROUGH);
TPMBackend *tb = TPM_BACKEND(obj);
TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
tb->id = g_strdup(id);
/* let frontend set the fe_model to proper value */
tb->fe_model = -1;
tb->ops = &tpm_passthrough_driver;
if (tpm_passthrough_handle_device_opts(opts, tb)) {
goto err_exit;
}
tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tb);
if (tpm_pt->cancel_fd < 0) {
goto err_exit;
}
return tb;
err_exit:
g_free(tb->id);
return NULL;
}
static void tpm_passthrough_destroy(TPMBackend *tb)
{
TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
tpm_passthrough_cancel_cmd(tb);
tpm_backend_thread_end(&tpm_pt->tbt);
qemu_close(tpm_pt->tpm_fd);
qemu_close(tpm_pt->cancel_fd);
g_free(tb->id);
g_free(tb->path);
g_free(tb->cancel_path);
g_free(tpm_pt->tpm_dev);
}
static const TPMDriverOps tpm_passthrough_driver = {
.type = TPM_TYPE_PASSTHROUGH,
.desc = tpm_passthrough_create_desc,
.create = tpm_passthrough_create,
.destroy = tpm_passthrough_destroy,
.init = tpm_passthrough_init,
.startup_tpm = tpm_passthrough_startup_tpm,
.realloc_buffer = tpm_passthrough_realloc_buffer,
.reset = tpm_passthrough_reset,
.had_startup_error = tpm_passthrough_get_startup_error,
.deliver_request = tpm_passthrough_deliver_request,
.cancel_cmd = tpm_passthrough_cancel_cmd,
.get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag,
};
static void tpm_passthrough_inst_init(Object *obj)
{
}
static void tpm_passthrough_inst_finalize(Object *obj)
{
}
static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
{
TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);
tbc->ops = &tpm_passthrough_driver;
}
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);
tpm_register_driver(&tpm_passthrough_driver);
}
type_init(tpm_passthrough_register)