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|
/*
* U2F USB Emulated device.
*
* Copyright (c) 2020 César Belley <cesar.belley@lse.epita.fr>
* Written by César Belley <cesar.belley@lse.epita.fr>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "qemu/module.h"
#include "qemu/thread.h"
#include "qemu/main-loop.h"
#include "qapi/error.h"
#include "hw/usb.h"
#include "hw/qdev-properties.h"
#include <u2f-emu/u2f-emu.h>
#include "u2f.h"
/* Counter which sync with a file */
struct synced_counter {
/* Emulated device counter */
struct u2f_emu_vdev_counter vdev_counter;
/* Private attributes */
uint32_t value;
FILE *fp;
};
static void counter_increment(struct u2f_emu_vdev_counter *vdev_counter)
{
struct synced_counter *counter = (struct synced_counter *)vdev_counter;
++counter->value;
/* Write back */
if (fseek(counter->fp, 0, SEEK_SET) == -1) {
return;
}
fprintf(counter->fp, "%u\n", counter->value);
}
static uint32_t counter_read(struct u2f_emu_vdev_counter *vdev_counter)
{
struct synced_counter *counter = (struct synced_counter *)vdev_counter;
return counter->value;
}
typedef struct U2FEmulatedState U2FEmulatedState;
#define PENDING_OUT_NUM 32
struct U2FEmulatedState {
U2FKeyState base;
/* U2F virtual emulated device */
u2f_emu_vdev *vdev;
QemuMutex vdev_mutex;
/* Properties */
char *dir;
char *cert;
char *privkey;
char *entropy;
char *counter;
struct synced_counter synced_counter;
/* Pending packets received from the guest */
uint8_t pending_out[PENDING_OUT_NUM][U2FHID_PACKET_SIZE];
uint8_t pending_out_start;
uint8_t pending_out_end;
uint8_t pending_out_num;
QemuMutex pending_out_mutex;
/* Emulation thread and sync */
QemuCond key_cond;
QemuMutex key_mutex;
QemuThread key_thread;
bool stop_thread;
EventNotifier notifier;
};
#define TYPE_U2F_EMULATED "u2f-emulated"
#define EMULATED_U2F_KEY(obj) \
OBJECT_CHECK(U2FEmulatedState, (obj), TYPE_U2F_EMULATED)
static void u2f_emulated_reset(U2FEmulatedState *key)
{
key->pending_out_start = 0;
key->pending_out_end = 0;
key->pending_out_num = 0;
}
static void u2f_pending_out_add(U2FEmulatedState *key,
const uint8_t packet[U2FHID_PACKET_SIZE])
{
int index;
if (key->pending_out_num >= PENDING_OUT_NUM) {
return;
}
index = key->pending_out_end;
key->pending_out_end = (index + 1) % PENDING_OUT_NUM;
++key->pending_out_num;
memcpy(&key->pending_out[index], packet, U2FHID_PACKET_SIZE);
}
static uint8_t *u2f_pending_out_get(U2FEmulatedState *key)
{
int index;
if (key->pending_out_num == 0) {
return NULL;
}
index = key->pending_out_start;
key->pending_out_start = (index + 1) % PENDING_OUT_NUM;
--key->pending_out_num;
return key->pending_out[index];
}
static void u2f_emulated_recv_from_guest(U2FKeyState *base,
const uint8_t packet[U2FHID_PACKET_SIZE])
{
U2FEmulatedState *key = EMULATED_U2F_KEY(base);
qemu_mutex_lock(&key->pending_out_mutex);
u2f_pending_out_add(key, packet);
qemu_mutex_unlock(&key->pending_out_mutex);
qemu_mutex_lock(&key->key_mutex);
qemu_cond_signal(&key->key_cond);
qemu_mutex_unlock(&key->key_mutex);
}
static void *u2f_emulated_thread(void* arg)
{
U2FEmulatedState *key = arg;
uint8_t packet[U2FHID_PACKET_SIZE];
uint8_t *packet_out = NULL;
while (true) {
/* Wait signal */
qemu_mutex_lock(&key->key_mutex);
qemu_cond_wait(&key->key_cond, &key->key_mutex);
qemu_mutex_unlock(&key->key_mutex);
/* Exit thread check */
if (key->stop_thread) {
key->stop_thread = false;
break;
}
qemu_mutex_lock(&key->pending_out_mutex);
packet_out = u2f_pending_out_get(key);
if (packet_out == NULL) {
qemu_mutex_unlock(&key->pending_out_mutex);
continue;
}
memcpy(packet, packet_out, U2FHID_PACKET_SIZE);
qemu_mutex_unlock(&key->pending_out_mutex);
qemu_mutex_lock(&key->vdev_mutex);
u2f_emu_vdev_send(key->vdev, U2F_EMU_USB, packet,
U2FHID_PACKET_SIZE);
/* Notify response */
if (u2f_emu_vdev_has_response(key->vdev, U2F_EMU_USB)) {
event_notifier_set(&key->notifier);
}
qemu_mutex_unlock(&key->vdev_mutex);
}
return NULL;
}
static ssize_t u2f_emulated_read(const char *path, char *buffer,
size_t buffer_len)
{
int fd;
ssize_t ret;
fd = qemu_open_old(path, O_RDONLY);
if (fd < 0) {
return -1;
}
ret = read(fd, buffer, buffer_len);
close(fd);
return ret;
}
static bool u2f_emulated_setup_counter(const char *path,
struct synced_counter *counter)
{
int fd, ret;
FILE *fp;
fd = qemu_open_old(path, O_RDWR);
if (fd < 0) {
return false;
}
fp = fdopen(fd, "r+");
if (fp == NULL) {
close(fd);
return false;
}
ret = fscanf(fp, "%u", &counter->value);
if (ret == EOF) {
fclose(fp);
return false;
}
counter->fp = fp;
counter->vdev_counter.counter_increment = counter_increment;
counter->vdev_counter.counter_read = counter_read;
return true;
}
static u2f_emu_rc u2f_emulated_setup_vdev_manualy(U2FEmulatedState *key)
{
ssize_t ret;
char cert_pem[4096], privkey_pem[2048];
struct u2f_emu_vdev_setup setup_info;
/* Certificate */
ret = u2f_emulated_read(key->cert, cert_pem, sizeof(cert_pem));
if (ret < 0) {
return -1;
}
/* Private key */
ret = u2f_emulated_read(key->privkey, privkey_pem, sizeof(privkey_pem));
if (ret < 0) {
return -1;
}
/* Entropy */
ret = u2f_emulated_read(key->entropy, (char *)&setup_info.entropy,
sizeof(setup_info.entropy));
if (ret < 0) {
return -1;
}
/* Counter */
if (!u2f_emulated_setup_counter(key->counter, &key->synced_counter)) {
return -1;
}
/* Setup */
setup_info.certificate = cert_pem;
setup_info.private_key = privkey_pem;
setup_info.counter = (struct u2f_emu_vdev_counter *)&key->synced_counter;
return u2f_emu_vdev_new(&key->vdev, &setup_info);
}
static void u2f_emulated_event_handler(EventNotifier *notifier)
{
U2FEmulatedState *key = container_of(notifier, U2FEmulatedState, notifier);
size_t packet_size;
uint8_t *packet_in = NULL;
event_notifier_test_and_clear(&key->notifier);
qemu_mutex_lock(&key->vdev_mutex);
while (u2f_emu_vdev_has_response(key->vdev, U2F_EMU_USB)) {
packet_size = u2f_emu_vdev_get_response(key->vdev, U2F_EMU_USB,
&packet_in);
if (packet_size == U2FHID_PACKET_SIZE) {
u2f_send_to_guest(&key->base, packet_in);
}
u2f_emu_vdev_free_response(packet_in);
}
qemu_mutex_unlock(&key->vdev_mutex);
}
static void u2f_emulated_realize(U2FKeyState *base, Error **errp)
{
U2FEmulatedState *key = EMULATED_U2F_KEY(base);
u2f_emu_rc rc;
if (key->cert != NULL || key->privkey != NULL || key->entropy != NULL
|| key->counter != NULL) {
if (key->cert != NULL && key->privkey != NULL
&& key->entropy != NULL && key->counter != NULL) {
rc = u2f_emulated_setup_vdev_manualy(key);
} else {
error_setg(errp, "%s: cert, priv, entropy and counter "
"parameters must be provided to manually configure "
"the emulated device", TYPE_U2F_EMULATED);
return;
}
} else if (key->dir != NULL) {
rc = u2f_emu_vdev_new_from_dir(&key->vdev, key->dir);
} else {
rc = u2f_emu_vdev_new_ephemeral(&key->vdev);
}
if (rc != U2F_EMU_OK) {
error_setg(errp, "%s: Failed to setup the key", TYPE_U2F_EMULATED);
return;
}
if (event_notifier_init(&key->notifier, false) < 0) {
error_setg(errp, "%s: Failed to initialize notifier",
TYPE_U2F_EMULATED);
return;
}
/* Notifier */
event_notifier_set_handler(&key->notifier, u2f_emulated_event_handler);
/* Synchronization */
qemu_cond_init(&key->key_cond);
qemu_mutex_init(&key->vdev_mutex);
qemu_mutex_init(&key->pending_out_mutex);
qemu_mutex_init(&key->key_mutex);
u2f_emulated_reset(key);
/* Thread */
key->stop_thread = false;
qemu_thread_create(&key->key_thread, "u2f-key", u2f_emulated_thread,
key, QEMU_THREAD_JOINABLE);
}
static void u2f_emulated_unrealize(U2FKeyState *base)
{
U2FEmulatedState *key = EMULATED_U2F_KEY(base);
/* Thread */
key->stop_thread = true;
qemu_cond_signal(&key->key_cond);
qemu_thread_join(&key->key_thread);
/* Notifier */
event_notifier_set_handler(&key->notifier, NULL);
event_notifier_cleanup(&key->notifier);
/* Synchronization */
qemu_cond_destroy(&key->key_cond);
qemu_mutex_destroy(&key->vdev_mutex);
qemu_mutex_destroy(&key->key_mutex);
qemu_mutex_destroy(&key->pending_out_mutex);
/* Vdev */
u2f_emu_vdev_free(key->vdev);
if (key->synced_counter.fp != NULL) {
fclose(key->synced_counter.fp);
}
}
static const Property u2f_emulated_properties[] = {
DEFINE_PROP_STRING("dir", U2FEmulatedState, dir),
DEFINE_PROP_STRING("cert", U2FEmulatedState, cert),
DEFINE_PROP_STRING("privkey", U2FEmulatedState, privkey),
DEFINE_PROP_STRING("entropy", U2FEmulatedState, entropy),
DEFINE_PROP_STRING("counter", U2FEmulatedState, counter),
};
static void u2f_emulated_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
U2FKeyClass *kc = U2F_KEY_CLASS(klass);
kc->realize = u2f_emulated_realize;
kc->unrealize = u2f_emulated_unrealize;
kc->recv_from_guest = u2f_emulated_recv_from_guest;
dc->desc = "QEMU U2F emulated key";
device_class_set_props(dc, u2f_emulated_properties);
}
static const TypeInfo u2f_key_emulated_info = {
.name = TYPE_U2F_EMULATED,
.parent = TYPE_U2F_KEY,
.instance_size = sizeof(U2FEmulatedState),
.class_init = u2f_emulated_class_init
};
static void u2f_key_emulated_register_types(void)
{
type_register_static(&u2f_key_emulated_info);
}
type_init(u2f_key_emulated_register_types)
|