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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 "IGateKeeperService.h"
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdint.h>
#include <unistd.h>
#include <android/log.h>
#include <binder/IPCThreadState.h>
#include <binder/IServiceManager.h>
#include <binder/PermissionCache.h>
#include <gatekeeper/password_handle.h> // for password_handle_t
#include <hardware/gatekeeper.h>
#include <hardware/hw_auth_token.h>
#include <keystore/IKeystoreService.h>
#include <keystore/keystore.h> // For error code
#include <utils/Log.h>
#include <utils/String16.h>
#include "SoftGateKeeperDevice.h"
#include "IUserManager.h"
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() {
int ret = hw_get_module_by_class(GATEKEEPER_HARDWARE_MODULE_ID, NULL, &module);
device = NULL;
if (ret < 0) {
ALOGW("falling back to software GateKeeper");
soft_device.reset(new SoftGateKeeperDevice());
} else {
ret = gatekeeper_open(module, &device);
if (ret < 0)
LOG_ALWAYS_FATAL_IF(ret < 0, "Unable to open GateKeeper HAL");
}
if (mark_cold_boot()) {
ALOGI("cold boot: clearing state");
if (device != NULL && device->delete_all_users != NULL) {
device->delete_all_users(device);
}
}
}
virtual ~GateKeeperProxy() {
if (device) gatekeeper_close(device);
}
void store_sid(uint32_t uid, uint64_t sid) {
char filename[21];
snprintf(filename, sizeof(filename), "%u", uid);
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);
}
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 uid, uint64_t sid) {
char filename[21];
snprintf(filename, sizeof(filename), "%u", uid);
if (access(filename, F_OK) == -1) {
store_sid(uid, sid);
}
}
uint64_t read_sid(uint32_t uid) {
char filename[21];
uint64_t sid;
snprintf(filename, sizeof(filename), "%u", uid);
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 uid) {
char filename[21];
snprintf(filename, sizeof(filename), "%u", uid);
if (remove(filename) < 0) {
ALOGE("%s: could not remove file [%s], attempting 0 write", __func__, strerror(errno));
store_sid(uid, 0);
}
}
virtual int enroll(uint32_t uid,
const uint8_t *current_password_handle, uint32_t current_password_handle_length,
const uint8_t *current_password, uint32_t current_password_length,
const uint8_t *desired_password, uint32_t desired_password_length,
uint8_t **enrolled_password_handle, uint32_t *enrolled_password_handle_length) {
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 PERMISSION_DENIED;
}
// need a desired password to enroll
if (desired_password_length == 0) return -EINVAL;
int ret;
if (device) {
const gatekeeper::password_handle_t *handle =
reinterpret_cast<const gatekeeper::password_handle_t *>(current_password_handle);
if (handle != NULL && handle->version != 0 && !handle->hardware_backed) {
// handle is being re-enrolled from a software version. HAL probably won't accept
// the handle as valid, so we nullify it and enroll from scratch
current_password_handle = NULL;
current_password_handle_length = 0;
current_password = NULL;
current_password_length = 0;
}
ret = device->enroll(device, uid, current_password_handle, current_password_handle_length,
current_password, current_password_length,
desired_password, desired_password_length,
enrolled_password_handle, enrolled_password_handle_length);
} else {
ret = soft_device->enroll(uid,
current_password_handle, current_password_handle_length,
current_password, current_password_length,
desired_password, desired_password_length,
enrolled_password_handle, enrolled_password_handle_length);
}
if (ret == 0) {
gatekeeper::password_handle_t *handle =
reinterpret_cast<gatekeeper::password_handle_t *>(*enrolled_password_handle);
store_sid(uid, handle->user_id);
bool rr;
// immediately verify this password so we don't ask the user to enter it again
// if they just created it.
verify(uid, *enrolled_password_handle, sizeof(password_handle_t), desired_password,
desired_password_length, &rr);
}
return ret;
}
virtual int verify(uint32_t uid,
const uint8_t *enrolled_password_handle, uint32_t enrolled_password_handle_length,
const uint8_t *provided_password, uint32_t provided_password_length, bool *request_reenroll) {
uint8_t *auth_token;
uint32_t auth_token_length;
return verifyChallenge(uid, 0, enrolled_password_handle, enrolled_password_handle_length,
provided_password, provided_password_length,
&auth_token, &auth_token_length, request_reenroll);
}
virtual int verifyChallenge(uint32_t uid, uint64_t challenge,
const uint8_t *enrolled_password_handle, uint32_t enrolled_password_handle_length,
const uint8_t *provided_password, uint32_t provided_password_length,
uint8_t **auth_token, uint32_t *auth_token_length, bool *request_reenroll) {
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 PERMISSION_DENIED;
}
// can't verify if we're missing either param
if ((enrolled_password_handle_length | provided_password_length) == 0)
return -EINVAL;
int ret;
if (device) {
const gatekeeper::password_handle_t *handle =
reinterpret_cast<const gatekeeper::password_handle_t *>(enrolled_password_handle);
// handle version 0 does not have hardware backed flag, and thus cannot be upgraded to
// a HAL if there was none before
if (handle->version == 0 || handle->hardware_backed) {
ret = device->verify(device, uid, challenge,
enrolled_password_handle, enrolled_password_handle_length,
provided_password, provided_password_length, auth_token, auth_token_length,
request_reenroll);
} else {
// upgrade scenario, a HAL has been added to this device where there was none before
SoftGateKeeperDevice soft_dev;
ret = soft_dev.verify(uid, challenge,
enrolled_password_handle, enrolled_password_handle_length,
provided_password, provided_password_length, auth_token, auth_token_length,
request_reenroll);
if (ret == 0) {
// success! re-enroll with HAL
*request_reenroll = true;
}
}
} else {
ret = soft_device->verify(uid, challenge,
enrolled_password_handle, enrolled_password_handle_length,
provided_password, provided_password_length, auth_token, auth_token_length,
request_reenroll);
}
if (ret == 0 && *auth_token != NULL && *auth_token_length > 0) {
// TODO: cache service?
sp<IServiceManager> sm = defaultServiceManager();
sp<IBinder> binder = sm->getService(String16("android.security.keystore"));
sp<IKeystoreService> service = interface_cast<IKeystoreService>(binder);
if (service != NULL) {
status_t ret = service->addAuthToken(*auth_token, *auth_token_length);
if (ret != ResponseCode::NO_ERROR) {
ALOGE("Falure sending auth token to KeyStore: %d", ret);
}
} else {
ALOGE("Unable to communicate with KeyStore");
}
}
if (ret == 0) {
maybe_store_sid(uid, reinterpret_cast<const gatekeeper::password_handle_t *>(
enrolled_password_handle)->user_id);
}
return ret;
}
virtual uint64_t getSecureUserId(uint32_t uid) {
uint64_t sid = read_sid(uid);
if (sid == 0) {
// might be a work profile, look up the parent
sp<IServiceManager> sm = defaultServiceManager();
sp<IBinder> binder = sm->getService(String16("user"));
sp<IUserManager> um = interface_cast<IUserManager>(binder);
int32_t parent = um->getCredentialOwnerProfile(uid);
if (parent < 0) {
return 0;
} else if (parent != (int32_t) uid) {
return read_sid(parent);
}
}
return sid;
}
virtual void clearSecureUserId(uint32_t uid) {
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;
}
clear_sid(uid);
if (device != NULL && device->delete_user != NULL) {
device->delete_user(device, uid);
}
}
virtual status_t dump(int fd, const Vector<String16> &) {
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 (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 NO_ERROR;
}
private:
gatekeeper_device_t *device;
UniquePtr<SoftGateKeeperDevice> soft_device;
const hw_module_t *module;
};
}// 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;
}