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/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "gatekeeperd"
#include <android/service/gatekeeper/BnGateKeeperService.h>
#include <gatekeeper/GateKeeperResponse.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <memory>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android/binder_ibinder.h>
#include <android/binder_manager.h>
#include <binder/IPCThreadState.h>
#include <binder/IServiceManager.h>
#include <binder/PermissionCache.h>
#include <gatekeeper/password_handle.h> // for password_handle_t
#include <hardware/hw_auth_token.h>
#include <libgsi/libgsi.h>
#include <log/log.h>
#include <utils/String16.h>
#include <aidl/android/hardware/security/keymint/HardwareAuthToken.h>
#include <aidl/android/security/authorization/IKeystoreAuthorization.h>
#include <android/hardware/gatekeeper/1.0/IGatekeeper.h>
#include <hidl/HidlSupport.h>
using android::sp;
using android::hardware::Return;
using android::hardware::gatekeeper::V1_0::GatekeeperResponse;
using android::hardware::gatekeeper::V1_0::GatekeeperStatusCode;
using android::hardware::gatekeeper::V1_0::IGatekeeper;
using ::android::binder::Status;
using ::android::service::gatekeeper::BnGateKeeperService;
using GKResponse = ::android::service::gatekeeper::GateKeeperResponse;
using GKResponseCode = ::android::service::gatekeeper::ResponseCode;
using ::aidl::android::hardware::security::keymint::HardwareAuthenticatorType;
using ::aidl::android::hardware::security::keymint::HardwareAuthToken;
using ::aidl::android::security::authorization::IKeystoreAuthorization;
namespace android {
static const String16 KEYGUARD_PERMISSION("android.permission.ACCESS_KEYGUARD_SECURE_STORAGE");
static const String16 DUMP_PERMISSION("android.permission.DUMP");
class GateKeeperProxy : public BnGateKeeperService {
public:
GateKeeperProxy() {
clear_state_if_needed_done = false;
hw_device = IGatekeeper::getService();
is_running_gsi = android::base::GetBoolProperty(android::gsi::kGsiBootedProp, false);
if (!hw_device) {
LOG(ERROR) << "Could not find Gatekeeper device, which makes me very sad.";
}
}
virtual ~GateKeeperProxy() {}
void store_sid(uint32_t userId, uint64_t sid) {
char filename[21];
snprintf(filename, sizeof(filename), "%u", userId);
int fd = open(filename, O_WRONLY | O_TRUNC | O_CREAT, S_IRUSR | S_IWUSR);
if (fd < 0) {
ALOGE("could not open file: %s: %s", filename, strerror(errno));
return;
}
write(fd, &sid, sizeof(sid));
close(fd);
}
void clear_state_if_needed() {
if (clear_state_if_needed_done) {
return;
}
if (mark_cold_boot() && !is_running_gsi) {
ALOGI("cold boot: clearing state");
if (hw_device) {
hw_device->deleteAllUsers([](const GatekeeperResponse&) {});
}
}
clear_state_if_needed_done = true;
}
bool mark_cold_boot() {
const char* filename = ".coldboot";
if (access(filename, F_OK) == -1) {
int fd = open(filename, O_WRONLY | O_TRUNC | O_CREAT, S_IRUSR | S_IWUSR);
if (fd < 0) {
ALOGE("could not open file: %s : %s", filename, strerror(errno));
return false;
}
close(fd);
return true;
}
return false;
}
void maybe_store_sid(uint32_t userId, uint64_t sid) {
char filename[21];
snprintf(filename, sizeof(filename), "%u", userId);
if (access(filename, F_OK) == -1) {
store_sid(userId, sid);
}
}
uint64_t read_sid(uint32_t userId) {
char filename[21];
uint64_t sid;
snprintf(filename, sizeof(filename), "%u", userId);
int fd = open(filename, O_RDONLY);
if (fd < 0) return 0;
read(fd, &sid, sizeof(sid));
close(fd);
return sid;
}
void clear_sid(uint32_t userId) {
char filename[21];
snprintf(filename, sizeof(filename), "%u", userId);
if (remove(filename) < 0) {
ALOGE("%s: could not remove file [%s], attempting 0 write", __func__, strerror(errno));
store_sid(userId, 0);
}
}
// This should only be called on userIds being passed to the GateKeeper HAL. It ensures that
// secure storage shared across a GSI image and a host image will not overlap.
uint32_t adjust_userId(uint32_t userId) {
static constexpr uint32_t kGsiOffset = 1000000;
CHECK(userId < kGsiOffset);
CHECK(hw_device != nullptr);
if (is_running_gsi) {
return userId + kGsiOffset;
}
return userId;
}
#define GK_ERROR *gkResponse = GKResponse::error(), Status::ok()
Status enroll(int32_t userId, const std::optional<std::vector<uint8_t>>& currentPasswordHandle,
const std::optional<std::vector<uint8_t>>& currentPassword,
const std::vector<uint8_t>& desiredPassword, GKResponse* gkResponse) override {
IPCThreadState* ipc = IPCThreadState::self();
const int calling_pid = ipc->getCallingPid();
const int calling_uid = ipc->getCallingUid();
if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
return GK_ERROR;
}
// Make sure to clear any state from before factory reset as soon as a credential is
// enrolled (which may happen during device setup).
clear_state_if_needed();
// need a desired password to enroll
if (desiredPassword.size() == 0) return GK_ERROR;
if (!hw_device) {
LOG(ERROR) << "has no HAL to talk to";
return GK_ERROR;
}
android::hardware::hidl_vec<uint8_t> curPwdHandle;
android::hardware::hidl_vec<uint8_t> curPwd;
if (currentPasswordHandle && currentPassword) {
if (currentPasswordHandle->size() != sizeof(gatekeeper::password_handle_t)) {
LOG(INFO) << "Password handle has wrong length";
return GK_ERROR;
}
curPwdHandle.setToExternal(const_cast<uint8_t*>(currentPasswordHandle->data()),
currentPasswordHandle->size());
curPwd.setToExternal(const_cast<uint8_t*>(currentPassword->data()),
currentPassword->size());
}
android::hardware::hidl_vec<uint8_t> newPwd;
newPwd.setToExternal(const_cast<uint8_t*>(desiredPassword.data()), desiredPassword.size());
uint32_t hw_userId = adjust_userId(userId);
Return<void> hwRes = hw_device->enroll(
hw_userId, curPwdHandle, curPwd, newPwd,
[&gkResponse](const GatekeeperResponse& rsp) {
if (rsp.code >= GatekeeperStatusCode::STATUS_OK) {
*gkResponse = GKResponse::ok({rsp.data.begin(), rsp.data.end()});
} else if (rsp.code == GatekeeperStatusCode::ERROR_RETRY_TIMEOUT &&
rsp.timeout > 0) {
*gkResponse = GKResponse::retry(rsp.timeout);
} else {
*gkResponse = GKResponse::error();
}
});
if (!hwRes.isOk()) {
LOG(ERROR) << "enroll transaction failed";
return GK_ERROR;
}
if (gkResponse->response_code() == GKResponseCode::OK && !gkResponse->should_reenroll()) {
if (gkResponse->payload().size() != sizeof(gatekeeper::password_handle_t)) {
LOG(ERROR) << "HAL returned password handle of invalid length "
<< gkResponse->payload().size();
return GK_ERROR;
}
const gatekeeper::password_handle_t* handle =
reinterpret_cast<const gatekeeper::password_handle_t*>(
gkResponse->payload().data());
store_sid(userId, handle->user_id);
GKResponse verifyResponse;
// immediately verify this password so we don't ask the user to enter it again
// if they just created it.
auto status = verify(userId, gkResponse->payload(), desiredPassword, &verifyResponse);
if (!status.isOk() || verifyResponse.response_code() != GKResponseCode::OK) {
LOG(ERROR) << "Failed to verify password after enrolling";
}
}
return Status::ok();
}
Status verify(int32_t userId, const ::std::vector<uint8_t>& enrolledPasswordHandle,
const ::std::vector<uint8_t>& providedPassword, GKResponse* gkResponse) override {
return verifyChallenge(userId, 0 /* challenge */, enrolledPasswordHandle, providedPassword,
gkResponse);
}
Status verifyChallenge(int32_t userId, int64_t challenge,
const std::vector<uint8_t>& enrolledPasswordHandle,
const std::vector<uint8_t>& providedPassword,
GKResponse* gkResponse) override {
IPCThreadState* ipc = IPCThreadState::self();
const int calling_pid = ipc->getCallingPid();
const int calling_uid = ipc->getCallingUid();
if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
return GK_ERROR;
}
// can't verify if we're missing either param
if (enrolledPasswordHandle.size() == 0 || providedPassword.size() == 0) return GK_ERROR;
if (!hw_device) return GK_ERROR;
if (enrolledPasswordHandle.size() != sizeof(gatekeeper::password_handle_t)) {
LOG(INFO) << "Password handle has wrong length";
return GK_ERROR;
}
const gatekeeper::password_handle_t* handle =
reinterpret_cast<const gatekeeper::password_handle_t*>(
enrolledPasswordHandle.data());
uint32_t hw_userId = adjust_userId(userId);
android::hardware::hidl_vec<uint8_t> curPwdHandle;
curPwdHandle.setToExternal(const_cast<uint8_t*>(enrolledPasswordHandle.data()),
enrolledPasswordHandle.size());
android::hardware::hidl_vec<uint8_t> enteredPwd;
enteredPwd.setToExternal(const_cast<uint8_t*>(providedPassword.data()),
providedPassword.size());
Return<void> hwRes = hw_device->verify(
hw_userId, challenge, curPwdHandle, enteredPwd,
[&gkResponse](const GatekeeperResponse& rsp) {
if (rsp.code >= GatekeeperStatusCode::STATUS_OK) {
*gkResponse = GKResponse::ok(
{rsp.data.begin(), rsp.data.end()},
rsp.code == GatekeeperStatusCode::STATUS_REENROLL /* reenroll */);
} else if (rsp.code == GatekeeperStatusCode::ERROR_RETRY_TIMEOUT) {
*gkResponse = GKResponse::retry(rsp.timeout);
} else {
*gkResponse = GKResponse::error();
}
});
if (!hwRes.isOk()) {
LOG(ERROR) << "verify transaction failed";
return GK_ERROR;
}
if (gkResponse->response_code() == GKResponseCode::OK) {
if (gkResponse->payload().size() != 0) {
// try to connect to IKeystoreAuthorization AIDL service first.
AIBinder* authzAIBinder =
AServiceManager_getService("android.security.authorization");
::ndk::SpAIBinder authzBinder(authzAIBinder);
auto authzService = IKeystoreAuthorization::fromBinder(authzBinder);
if (authzService) {
if (gkResponse->payload().size() != sizeof(hw_auth_token_t)) {
LOG(ERROR) << "Incorrect size of AuthToken payload.";
return GK_ERROR;
}
const hw_auth_token_t* hwAuthToken =
reinterpret_cast<const hw_auth_token_t*>(gkResponse->payload().data());
HardwareAuthToken authToken;
authToken.timestamp.milliSeconds = betoh64(hwAuthToken->timestamp);
authToken.challenge = hwAuthToken->challenge;
authToken.userId = hwAuthToken->user_id;
authToken.authenticatorId = hwAuthToken->authenticator_id;
authToken.authenticatorType = static_cast<HardwareAuthenticatorType>(
betoh32(hwAuthToken->authenticator_type));
authToken.mac.assign(&hwAuthToken->hmac[0], &hwAuthToken->hmac[32]);
auto result = authzService->addAuthToken(authToken);
if (!result.isOk()) {
LOG(ERROR) << "Failure in sending AuthToken to AuthorizationService.";
return GK_ERROR;
}
} else {
LOG(ERROR) << "Cannot deliver auth token. Unable to communicate with "
"Keystore.";
return GK_ERROR;
}
}
maybe_store_sid(userId, handle->user_id);
}
return Status::ok();
}
Status getSecureUserId(int32_t userId, int64_t* sid) override {
*sid = read_sid(userId);
return Status::ok();
}
Status clearSecureUserId(int32_t userId) override {
IPCThreadState* ipc = IPCThreadState::self();
const int calling_pid = ipc->getCallingPid();
const int calling_uid = ipc->getCallingUid();
if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
ALOGE("%s: permission denied for [%d:%d]", __func__, calling_pid, calling_uid);
return Status::ok();
}
clear_sid(userId);
if (hw_device) {
uint32_t hw_userId = adjust_userId(userId);
hw_device->deleteUser(hw_userId, [](const GatekeeperResponse&) {});
}
return Status::ok();
}
Status reportDeviceSetupComplete() override {
IPCThreadState* ipc = IPCThreadState::self();
const int calling_pid = ipc->getCallingPid();
const int calling_uid = ipc->getCallingUid();
if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
ALOGE("%s: permission denied for [%d:%d]", __func__, calling_pid, calling_uid);
return Status::ok();
}
clear_state_if_needed();
return Status::ok();
}
status_t dump(int fd, const Vector<String16>&) override {
IPCThreadState* ipc = IPCThreadState::self();
const int pid = ipc->getCallingPid();
const int uid = ipc->getCallingUid();
if (!PermissionCache::checkPermission(DUMP_PERMISSION, pid, uid)) {
return PERMISSION_DENIED;
}
if (hw_device == NULL) {
const char* result = "Device not available";
write(fd, result, strlen(result) + 1);
} else {
const char* result = "OK";
write(fd, result, strlen(result) + 1);
}
return OK;
}
private:
sp<IGatekeeper> hw_device;
bool clear_state_if_needed_done;
bool is_running_gsi;
};
} // namespace android
int main(int argc, char* argv[]) {
ALOGI("Starting gatekeeperd...");
if (argc < 2) {
ALOGE("A directory must be specified!");
return 1;
}
if (chdir(argv[1]) == -1) {
ALOGE("chdir: %s: %s", argv[1], strerror(errno));
return 1;
}
android::sp<android::IServiceManager> sm = android::defaultServiceManager();
android::sp<android::GateKeeperProxy> proxy = new android::GateKeeperProxy();
android::status_t ret = sm->addService(
android::String16("android.service.gatekeeper.IGateKeeperService"), proxy);
if (ret != android::OK) {
ALOGE("Couldn't register binder service!");
return -1;
}
/*
* We're the only thread in existence, so we're just going to process
* Binder transaction as a single-threaded program.
*/
android::IPCThreadState::self()->joinThreadPool();
return 0;
}