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/*
* Copyright (C) 2016 The Team Win Recovery 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.
*/
#include "Decrypt.h"
#include "Ext4Crypt.h"
#include <string>
#include <errno.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include "ext4_crypt.h"
#include "key_control.h"
#include <hardware/gatekeeper.h>
#include "HashPassword.h"
#include <android-base/file.h>
int gatekeeper_device_initialize(gatekeeper_device_t **dev) {
int ret;
const hw_module_t *mod;
ret = hw_get_module_by_class(GATEKEEPER_HARDWARE_MODULE_ID, NULL, &mod);
if (ret!=0) {
printf("failed to get hw module\n");
return ret;
}
ret = gatekeeper_open(mod, dev);
if (ret!=0)
printf("failed to open gatekeeper\n");
return ret;
}
int Get_Password_Type(const userid_t user_id, std::string& filename) {
std::string path;
if (user_id == 0) {
path = "/data/system/";
} else {
char user_id_str[5];
sprintf(user_id_str, "%i", user_id);
path = "/data/system/users/";
path += user_id_str;
path += "/";
}
filename = path + "gatekeeper.password.key";
struct stat st;
if (stat(filename.c_str(), &st) == 0 && st.st_size > 0)
return 1;
filename = path + "gatekeeper.pattern.key";
if (stat(filename.c_str(), &st) == 0 && st.st_size > 0)
return 2;
printf("Unable to locate gatekeeper password file '%s'\n", filename.c_str());
filename = "";
return 0;
}
bool Decrypt_DE() {
if (!e4crypt_initialize_global_de()) { // this deals with the overarching device encryption
printf("e4crypt_initialize_global_de returned fail\n");
return false;
}
if (!e4crypt_init_user0()) {
printf("e4crypt_init_user0 returned fail\n");
return false;
}
return true;
}
bool Decrypt_User(const userid_t user_id, const std::string& Password) {
uint8_t *auth_token;
uint32_t auth_token_len;
int ret;
struct stat st;
if (user_id > 9999) {
printf("user_id is too big\n");
return false;
}
std::string filename;
bool Default_Password = (Password == "!");
if (Get_Password_Type(user_id, filename) == 0 && !Default_Password) {
printf("Unknown password type\n");
return false;
}
int flags = FLAG_STORAGE_DE;
if (user_id == 0)
flags = FLAG_STORAGE_DE;
else
flags = FLAG_STORAGE_CE;
gatekeeper_device_t *device;
ret = gatekeeper_device_initialize(&device);
if (Default_Password) {
if (!e4crypt_unlock_user_key(user_id, 0, "!", "!")) {
printf("e4crypt_unlock_user_key returned fail\n");
return false;
}
if (!e4crypt_prepare_user_storage(nullptr, user_id, 0, flags)) {
printf("failed to e4crypt_prepare_user_storage\n");
return false;
}
printf("Decrypted Successfully!\n");
return true;
}
if (ret!=0)
return false;
printf("password filename is '%s'\n", filename.c_str());
if (stat(filename.c_str(), &st) != 0) {
printf("error stat'ing key file: %s\n", strerror(errno));
return false;
}
std::string handle;
if (!android::base::ReadFileToString(filename, &handle)) {
printf("Failed to read '%s'\n", filename.c_str());
return false;
}
bool should_reenroll;
ret = device->verify(device, user_id, 0, (const uint8_t *)handle.c_str(), st.st_size,
(const uint8_t *)Password.c_str(), (uint32_t)Password.size(), &auth_token, &auth_token_len,
&should_reenroll);
if (ret !=0) {
printf("failed to verify\n");
return false;
}
char token_hex[(auth_token_len*2)+1];
token_hex[(auth_token_len*2)] = 0;
uint32_t i;
for (i=0;i<auth_token_len;i++) {
sprintf(&token_hex[2*i], "%02X", auth_token[i]);
}
// The secret is "Android FBE credential hash" plus appended 0x00 to reach 128 bytes then append the user's password then feed that to sha512sum
std::string secret = HashPassword(Password);
if (!e4crypt_unlock_user_key(user_id, 0, token_hex, secret.c_str())) {
printf("e4crypt_unlock_user_key returned fail\n");
return false;
}
if (!e4crypt_prepare_user_storage(nullptr, user_id, 0, flags)) {
printf("failed to e4crypt_prepare_user_storage\n");
return false;
}
printf("Decrypted Successfully!\n");
return true;
}
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