s_security.h

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/*
Minetest
Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
 
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
 
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Lesser General Public License for more details.
 
You should have received a copy of the GNU Lesser General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
 
#pragma once
 
#include "cpp_api/s_base.h"
 
 
#define CHECK_SECURE_PATH_INTERNAL(L, path, write_required, ptr) \
    if (!ScriptApiSecurity::checkPath(L, path, write_required, ptr)) { \
        throw LuaError(std::string("Mod security: Blocked attempted ") + \
                (write_required ? "write to " : "read from ") + path); \
    }
#define CHECK_SECURE_PATH(L, path, write_required) \
    if (ScriptApiSecurity::isSecure(L)) { \
        CHECK_SECURE_PATH_INTERNAL(L, path, write_required, NULL); \
    }
#define CHECK_SECURE_PATH_POSSIBLE_WRITE(L, path, ptr) \
    if (ScriptApiSecurity::isSecure(L)) { \
        CHECK_SECURE_PATH_INTERNAL(L, path, false, ptr); \
    }
 
 
class ScriptApiSecurity : virtual public ScriptApiBase
{
public:
    // Sets up security on the ScriptApi's Lua state
    void initializeSecurity();
    void initializeSecurityClient();
    // Checks if the Lua state has been secured
    static bool isSecure(lua_State *L);
    // Loads a string as Lua code safely (doesn't allow bytecode).
    static bool safeLoadString(lua_State *L, const std::string &code, const char *chunk_name);
    // Loads a file as Lua code safely (doesn't allow bytecode).
    static bool safeLoadFile(lua_State *L, const char *path, const char *display_name = NULL);
    // Check if mod is whitelisted in the given setting
    // This additionally checks that the mod's main file scope is executing.
    static bool checkWhitelisted(lua_State *L, const std::string &setting);
    // Checks if mods are allowed to read (and optionally write) to the path
    static bool checkPath(lua_State *L, const char *path, bool write_required,
            bool *write_allowed=NULL);
 
private:
    int getThread(lua_State *L);
    // sets the enviroment to the table thats on top of the stack
    void setLuaEnv(lua_State *L, int thread);
    // creates an empty Lua environment
    void createEmptyEnv(lua_State *L);
 
    // Syntax: "sl_" <Library name or 'g' (global)> '_' <Function name>
    // (sl stands for Secure Lua)
 
    static int sl_g_dofile(lua_State *L);
    static int sl_g_load(lua_State *L);
    static int sl_g_loadfile(lua_State *L);
    static int sl_g_loadstring(lua_State *L);
    static int sl_g_require(lua_State *L);
 
    static int sl_io_open(lua_State *L);
    static int sl_io_input(lua_State *L);
    static int sl_io_output(lua_State *L);
    static int sl_io_lines(lua_State *L);
 
    static int sl_os_rename(lua_State *L);
    static int sl_os_remove(lua_State *L);
    static int sl_os_setlocale(lua_State *L);
};