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/*
* Copyright (C) 2009 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.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include "encryptedfs_provisioning.h"
#include "cutils/misc.h"
#include "cutils/properties.h"
#include "common.h"
#include "mtdutils/mtdutils.h"
#include "mounts.h"
#include "roots.h"
const char* encrypted_fs_enabled_property = "persist.security.secfs.enabled";
const char* encrypted_fs_property_dir = "/data/property/";
const char* encrypted_fs_system_dir = "/data/system/";
const char* encrypted_fs_key_file_name = "/data/fs_key.dat";
const char* encrypted_fs_salt_file_name = "/data/hash_salt.dat";
const char* encrypted_fs_hash_file_src_name = "/data/system/password.key";
const char* encrypted_fs_hash_file_dst_name = "/data/hash.dat";
const char* encrypted_fs_entropy_file_src_name = "/data/system/entropy.dat";
const char* encrypted_fs_entropy_file_dst_name = "/data/ported_entropy.dat";
void get_property_file_name(char *buffer, const char *property_name) {
sprintf(buffer, "%s%s", encrypted_fs_property_dir, property_name);
}
int get_binary_file_contents(char *buffer, int buf_size, const char *file_name, int *out_size) {
FILE *in_file;
int read_bytes;
in_file = fopen(file_name, "r");
if (in_file == NULL) {
LOGE("Secure FS: error accessing key file.");
return ENCRYPTED_FS_ERROR;
}
read_bytes = fread(buffer, 1, buf_size, in_file);
if (out_size == NULL) {
if (read_bytes != buf_size) {
// Error or unexpected data
fclose(in_file);
LOGE("Secure FS: error reading conmplete key.");
return ENCRYPTED_FS_ERROR;
}
} else {
*out_size = read_bytes;
}
fclose(in_file);
return ENCRYPTED_FS_OK;
}
int set_binary_file_contents(char *buffer, int buf_size, const char *file_name) {
FILE *out_file;
int write_bytes;
out_file = fopen(file_name, "w");
if (out_file == NULL) {
LOGE("Secure FS: error setting up key file.");
return ENCRYPTED_FS_ERROR;
}
write_bytes = fwrite(buffer, 1, buf_size, out_file);
if (write_bytes != buf_size) {
// Error or unexpected data
fclose(out_file);
LOGE("Secure FS: error reading conmplete key.");
return ENCRYPTED_FS_ERROR;
}
fclose(out_file);
return ENCRYPTED_FS_OK;
}
int get_text_file_contents(char *buffer, int buf_size, char *file_name) {
FILE *in_file;
char *read_data;
in_file = fopen(file_name, "r");
if (in_file == NULL) {
LOGE("Secure FS: error accessing properties.");
return ENCRYPTED_FS_ERROR;
}
read_data = fgets(buffer, buf_size, in_file);
if (read_data == NULL) {
// Error or unexpected data
fclose(in_file);
LOGE("Secure FS: error accessing properties.");
return ENCRYPTED_FS_ERROR;
}
fclose(in_file);
return ENCRYPTED_FS_OK;
}
int set_text_file_contents(char *buffer, char *file_name) {
FILE *out_file;
int result;
out_file = fopen(file_name, "w");
if (out_file == NULL) {
LOGE("Secure FS: error setting up properties.");
return ENCRYPTED_FS_ERROR;
}
result = fputs(buffer, out_file);
if (result != 0) {
// Error or unexpected data
fclose(out_file);
LOGE("Secure FS: error setting up properties.");
return ENCRYPTED_FS_ERROR;
}
fflush(out_file);
fclose(out_file);
return ENCRYPTED_FS_OK;
}
int read_encrypted_fs_boolean_property(const char *prop_name, int *value) {
char prop_file_name[PROPERTY_KEY_MAX + 32];
char prop_value[PROPERTY_VALUE_MAX];
int result;
get_property_file_name(prop_file_name, prop_name);
result = get_text_file_contents(prop_value, PROPERTY_VALUE_MAX, prop_file_name);
if (result < 0) {
return result;
}
if (strncmp(prop_value, "1", 1) == 0) {
*value = 1;
} else if (strncmp(prop_value, "0", 1) == 0) {
*value = 0;
} else {
LOGE("Secure FS: error accessing properties.");
return ENCRYPTED_FS_ERROR;
}
return ENCRYPTED_FS_OK;
}
int write_encrypted_fs_boolean_property(const char *prop_name, int value) {
char prop_file_name[PROPERTY_KEY_MAX + 32];
char prop_value[PROPERTY_VALUE_MAX];
int result;
get_property_file_name(prop_file_name, prop_name);
// Create the directory if needed
mkdir(encrypted_fs_property_dir, 0755);
if (value == 1) {
result = set_text_file_contents("1", prop_file_name);
} else if (value == 0) {
result = set_text_file_contents("0", prop_file_name);
} else {
return ENCRYPTED_FS_ERROR;
}
if (result < 0) {
return result;
}
return ENCRYPTED_FS_OK;
}
int read_encrypted_fs_info(encrypted_fs_info *encrypted_fs_data) {
int result;
int value;
result = ensure_path_mounted("/data");
if (result != 0) {
LOGE("Secure FS: error mounting userdata partition.");
return ENCRYPTED_FS_ERROR;
}
// Read the pre-generated encrypted FS key, password hash and salt.
result = get_binary_file_contents(encrypted_fs_data->key, ENCRYPTED_FS_KEY_SIZE,
encrypted_fs_key_file_name, NULL);
if (result != 0) {
LOGE("Secure FS: error reading generated file system key.");
return ENCRYPTED_FS_ERROR;
}
result = get_binary_file_contents(encrypted_fs_data->salt, ENCRYPTED_FS_SALT_SIZE,
encrypted_fs_salt_file_name, &(encrypted_fs_data->salt_length));
if (result != 0) {
LOGE("Secure FS: error reading file system salt.");
return ENCRYPTED_FS_ERROR;
}
result = get_binary_file_contents(encrypted_fs_data->hash, ENCRYPTED_FS_MAX_HASH_SIZE,
encrypted_fs_hash_file_src_name, &(encrypted_fs_data->hash_length));
if (result != 0) {
LOGE("Secure FS: error reading password hash.");
return ENCRYPTED_FS_ERROR;
}
result = get_binary_file_contents(encrypted_fs_data->entropy, ENTROPY_MAX_SIZE,
encrypted_fs_entropy_file_src_name, &(encrypted_fs_data->entropy_length));
if (result != 0) {
LOGE("Secure FS: error reading ported entropy.");
return ENCRYPTED_FS_ERROR;
}
result = ensure_path_unmounted("/data");
if (result != 0) {
LOGE("Secure FS: error unmounting data partition.");
return ENCRYPTED_FS_ERROR;
}
return ENCRYPTED_FS_OK;
}
int restore_encrypted_fs_info(encrypted_fs_info *encrypted_fs_data) {
int result;
result = ensure_path_mounted("/data");
if (result != 0) {
LOGE("Secure FS: error mounting userdata partition.");
return ENCRYPTED_FS_ERROR;
}
// Write the pre-generated secure FS key, password hash and salt.
result = set_binary_file_contents(encrypted_fs_data->key, ENCRYPTED_FS_KEY_SIZE,
encrypted_fs_key_file_name);
if (result != 0) {
LOGE("Secure FS: error writing generated file system key.");
return ENCRYPTED_FS_ERROR;
}
result = set_binary_file_contents(encrypted_fs_data->salt, encrypted_fs_data->salt_length,
encrypted_fs_salt_file_name);
if (result != 0) {
LOGE("Secure FS: error writing file system salt.");
return ENCRYPTED_FS_ERROR;
}
result = set_binary_file_contents(encrypted_fs_data->hash, encrypted_fs_data->hash_length,
encrypted_fs_hash_file_dst_name);
if (result != 0) {
LOGE("Secure FS: error writing password hash.");
return ENCRYPTED_FS_ERROR;
}
result = set_binary_file_contents(encrypted_fs_data->entropy, encrypted_fs_data->entropy_length,
encrypted_fs_entropy_file_dst_name);
if (result != 0) {
LOGE("Secure FS: error writing ported entropy.");
return ENCRYPTED_FS_ERROR;
}
// Set the secure FS properties to their respective values
result = write_encrypted_fs_boolean_property(encrypted_fs_enabled_property, encrypted_fs_data->mode);
if (result != 0) {
return result;
}
result = ensure_path_unmounted("/data");
if (result != 0) {
LOGE("Secure FS: error unmounting data partition.");
return ENCRYPTED_FS_ERROR;
}
return ENCRYPTED_FS_OK;
}