godot/core/io/file_access_encrypted.cpp
Fabio Alessandrelli 564d93ff10 CryptoCore class to access to base crypto utils.
Godot core needs MD5/SHA256/AES/Base64 which used to be provided by
separate libraries.
Since we bundle mbedtls in most cases, and we can easily only include
the needed sources if we so desire, let's use it.

To simplify library changes in the future, and better isolate header
dependencies all functions have been wrapped around inside a class in
`core/math/crypto_base.h`.

If the mbedtls module is disabled, we only bundle the needed source
files independently of the `builtin_mbedtls` option.
If the module is enabled, the `builtin_mbedtls` option works as usual.

Also remove some unused headers from StreamPeerMbedTLS which were
causing build issues.
2019-07-02 12:36:27 +02:00

319 lines
7.8 KiB
C++

/*************************************************************************/
/* file_access_encrypted.cpp */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2019 Godot Engine contributors (cf. AUTHORS.md) */
/* */
/* 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 "file_access_encrypted.h"
#include "core/math/crypto_core.h"
#include "core/os/copymem.h"
#include "core/print_string.h"
#include "core/variant.h"
#include <stdio.h>
#define COMP_MAGIC 0x43454447
Error FileAccessEncrypted::open_and_parse(FileAccess *p_base, const Vector<uint8_t> &p_key, Mode p_mode) {
ERR_FAIL_COND_V(file != NULL, ERR_ALREADY_IN_USE);
ERR_FAIL_COND_V(p_key.size() != 32, ERR_INVALID_PARAMETER);
pos = 0;
eofed = false;
if (p_mode == MODE_WRITE_AES256) {
data.clear();
writing = true;
file = p_base;
mode = p_mode;
key = p_key;
} else if (p_mode == MODE_READ) {
writing = false;
key = p_key;
uint32_t magic = p_base->get_32();
ERR_FAIL_COND_V(magic != COMP_MAGIC, ERR_FILE_UNRECOGNIZED);
mode = Mode(p_base->get_32());
ERR_FAIL_INDEX_V(mode, MODE_MAX, ERR_FILE_CORRUPT);
ERR_FAIL_COND_V(mode == 0, ERR_FILE_CORRUPT);
unsigned char md5d[16];
p_base->get_buffer(md5d, 16);
length = p_base->get_64();
base = p_base->get_position();
ERR_FAIL_COND_V(p_base->get_len() < base + length, ERR_FILE_CORRUPT);
uint32_t ds = length;
if (ds % 16) {
ds += 16 - (ds % 16);
}
data.resize(ds);
uint32_t blen = p_base->get_buffer(data.ptrw(), ds);
ERR_FAIL_COND_V(blen != ds, ERR_FILE_CORRUPT);
CryptoCore::AESContext ctx;
ctx.set_decode_key(key.ptrw(), 256);
for (size_t i = 0; i < ds; i += 16) {
ctx.decrypt_ecb(&data.write[i], &data.write[i]);
}
data.resize(length);
unsigned char hash[16];
ERR_FAIL_COND_V(CryptoCore::md5(data.ptr(), data.size(), hash) != OK, ERR_BUG);
ERR_EXPLAIN("The MD5 sum of the decrypted file does not match the expected value. It could be that the file is corrupt, or that the provided decryption key is invalid.");
ERR_FAIL_COND_V(String::md5(hash) != String::md5(md5d), ERR_FILE_CORRUPT);
file = p_base;
}
return OK;
}
Error FileAccessEncrypted::open_and_parse_password(FileAccess *p_base, const String &p_key, Mode p_mode) {
String cs = p_key.md5_text();
ERR_FAIL_COND_V(cs.length() != 32, ERR_INVALID_PARAMETER);
Vector<uint8_t> key;
key.resize(32);
for (int i = 0; i < 32; i++) {
key.write[i] = cs[i];
}
return open_and_parse(p_base, key, p_mode);
}
Error FileAccessEncrypted::_open(const String &p_path, int p_mode_flags) {
return OK;
}
void FileAccessEncrypted::close() {
if (!file)
return;
if (writing) {
Vector<uint8_t> compressed;
size_t len = data.size();
if (len % 16) {
len += 16 - (len % 16);
}
unsigned char hash[16];
ERR_FAIL_COND(CryptoCore::md5(data.ptr(), data.size(), hash) != OK); // Bug?
compressed.resize(len);
zeromem(compressed.ptrw(), len);
for (int i = 0; i < data.size(); i++) {
compressed.write[i] = data[i];
}
CryptoCore::AESContext ctx;
ctx.set_encode_key(key.ptrw(), 256);
for (size_t i = 0; i < len; i += 16) {
ctx.encrypt_ecb(&compressed.write[i], &compressed.write[i]);
}
file->store_32(COMP_MAGIC);
file->store_32(mode);
file->store_buffer(hash, 16);
file->store_64(data.size());
file->store_buffer(compressed.ptr(), compressed.size());
file->close();
memdelete(file);
file = NULL;
data.clear();
} else {
file->close();
memdelete(file);
data.clear();
file = NULL;
}
}
bool FileAccessEncrypted::is_open() const {
return file != NULL;
}
void FileAccessEncrypted::seek(size_t p_position) {
if (p_position > (size_t)data.size())
p_position = data.size();
pos = p_position;
eofed = false;
}
void FileAccessEncrypted::seek_end(int64_t p_position) {
seek(data.size() + p_position);
}
size_t FileAccessEncrypted::get_position() const {
return pos;
}
size_t FileAccessEncrypted::get_len() const {
return data.size();
}
bool FileAccessEncrypted::eof_reached() const {
return eofed;
}
uint8_t FileAccessEncrypted::get_8() const {
ERR_FAIL_COND_V(writing, 0);
if (pos >= data.size()) {
eofed = true;
return 0;
}
uint8_t b = data[pos];
pos++;
return b;
}
int FileAccessEncrypted::get_buffer(uint8_t *p_dst, int p_length) const {
ERR_FAIL_COND_V(writing, 0);
int to_copy = MIN(p_length, data.size() - pos);
for (int i = 0; i < to_copy; i++) {
p_dst[i] = data[pos++];
}
if (to_copy < p_length) {
eofed = true;
}
return to_copy;
}
Error FileAccessEncrypted::get_error() const {
return eofed ? ERR_FILE_EOF : OK;
}
void FileAccessEncrypted::store_buffer(const uint8_t *p_src, int p_length) {
ERR_FAIL_COND(!writing);
if (pos < data.size()) {
for (int i = 0; i < p_length; i++) {
store_8(p_src[i]);
}
} else if (pos == data.size()) {
data.resize(pos + p_length);
for (int i = 0; i < p_length; i++) {
data.write[pos + i] = p_src[i];
}
pos += p_length;
}
}
void FileAccessEncrypted::flush() {
ERR_FAIL_COND(!writing);
// encrypted files keep data in memory till close()
}
void FileAccessEncrypted::store_8(uint8_t p_dest) {
ERR_FAIL_COND(!writing);
if (pos < data.size()) {
data.write[pos] = p_dest;
pos++;
} else if (pos == data.size()) {
data.push_back(p_dest);
pos++;
}
}
bool FileAccessEncrypted::file_exists(const String &p_name) {
FileAccess *fa = FileAccess::open(p_name, FileAccess::READ);
if (!fa)
return false;
memdelete(fa);
return true;
}
uint64_t FileAccessEncrypted::_get_modified_time(const String &p_file) {
return 0;
}
uint32_t FileAccessEncrypted::_get_unix_permissions(const String &p_file) {
return 0;
}
Error FileAccessEncrypted::_set_unix_permissions(const String &p_file, uint32_t p_permissions) {
ERR_PRINT("Setting UNIX permissions on encrypted files is not implemented yet");
return ERR_UNAVAILABLE;
}
FileAccessEncrypted::FileAccessEncrypted() {
file = NULL;
pos = 0;
eofed = false;
mode = MODE_MAX;
writing = false;
}
FileAccessEncrypted::~FileAccessEncrypted() {
if (file)
close();
}