godot/core/io/file_access_encrypted.cpp
Rémi Verschelde 32047ffd9c
FileAccess: Don't err in store_buffer with buffer of size 0
The error check was added for `FileAccessUnix` but it's not an error when both
`p_src` and `p_length` are zero.

Added correct error checks to all implementations to prevent the actual
erroneous case: `p_src` is nullptr but `p_length > 0` (risk of null pointer
indexing).

Fixes #33564.

(cherry picked from commit 01d5c463be)
2021-06-07 22:36:07 +02:00

310 lines
8.5 KiB
C++

/*************************************************************************/
/* file_access_encrypted.cpp */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2021 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/crypto/crypto_core.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_MSG(file != nullptr, ERR_ALREADY_IN_USE, "Can't open file while another file from path '" + file->get_path_absolute() + "' is open.");
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);
uint64_t ds = length;
if (ds % 16) {
ds += 16 - (ds % 16);
}
data.resize(ds);
uint64_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 (uint64_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_FAIL_COND_V_MSG(String::md5(hash) != String::md5(md5d), ERR_FILE_CORRUPT, "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.");
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;
uint64_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);
memset(compressed.ptrw(), 0, 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 (uint64_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 = nullptr;
data.clear();
} else {
file->close();
memdelete(file);
data.clear();
file = nullptr;
}
}
bool FileAccessEncrypted::is_open() const {
return file != nullptr;
}
String FileAccessEncrypted::get_path() const {
if (file) {
return file->get_path();
} else {
return "";
}
}
String FileAccessEncrypted::get_path_absolute() const {
if (file) {
return file->get_path_absolute();
} else {
return "";
}
}
void FileAccessEncrypted::seek(uint64_t p_position) {
if (p_position > get_len()) {
p_position = get_len();
}
pos = p_position;
eofed = false;
}
void FileAccessEncrypted::seek_end(int64_t p_position) {
seek(get_len() + p_position);
}
uint64_t FileAccessEncrypted::get_position() const {
return pos;
}
uint64_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_MSG(writing, 0, "File has not been opened in read mode.");
if (pos >= get_len()) {
eofed = true;
return 0;
}
uint8_t b = data[pos];
pos++;
return b;
}
uint64_t FileAccessEncrypted::get_buffer(uint8_t *p_dst, uint64_t p_length) const {
ERR_FAIL_COND_V(!p_dst && p_length > 0, -1);
ERR_FAIL_COND_V_MSG(writing, -1, "File has not been opened in read mode.");
uint64_t to_copy = MIN(p_length, get_len() - pos);
for (uint64_t 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, uint64_t p_length) {
ERR_FAIL_COND_MSG(!writing, "File has not been opened in write mode.");
ERR_FAIL_COND(!p_src && p_length > 0);
if (pos < get_len()) {
for (uint64_t i = 0; i < p_length; i++) {
store_8(p_src[i]);
}
} else if (pos == get_len()) {
data.resize(pos + p_length);
for (uint64_t i = 0; i < p_length; i++) {
data.write[pos + i] = p_src[i];
}
pos += p_length;
}
}
void FileAccessEncrypted::flush() {
ERR_FAIL_COND_MSG(!writing, "File has not been opened in write mode.");
// encrypted files keep data in memory till close()
}
void FileAccessEncrypted::store_8(uint8_t p_dest) {
ERR_FAIL_COND_MSG(!writing, "File has not been opened in write mode.");
if (pos < get_len()) {
data.write[pos] = p_dest;
pos++;
} else if (pos == get_len()) {
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 = nullptr;
pos = 0;
eofed = false;
mode = MODE_MAX;
writing = false;
}
FileAccessEncrypted::~FileAccessEncrypted() {
if (file) {
close();
}
}