s_security.h

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// Luanti
// SPDX-License-Identifier: LGPL-2.1-or-later
// Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
 
#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, nullptr); \
        }
 
#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();
#if CHECK_CLIENT_BUILD()
        void initializeSecurityClient();
        void initializeSecuritySSCSM();
#else
        void initializeSecurityClient() { assert(0); }
        void initializeSecuritySSCSM() { assert(0); }
#endif
 
        // Checks if the Lua state has been secured
        static bool isSecure(lua_State *L);
        // Leaves the untampered globals (table) on top of the stack
        static void getGlobalsBackup(lua_State *L);

        static bool safeLoadString(lua_State *L, std::string_view code, const char *chunk_name);
        static bool safeLoadFileContent(lua_State *L, std::string_view code, const char *chunk_name);
        static bool safeLoadFile(lua_State *L, const char *path, const char *display_name = nullptr);

        static std::string getCurrentModName(lua_State *L);
        static bool checkWhitelisted(lua_State *L, const std::string &setting);

        static bool checkPath(lua_State *L, const char *path, bool write_required,
                        bool *write_allowed = nullptr);
 
protected:
        // To be implemented by descendants:

        virtual bool modNamesAreTrusted() { return false; }

        virtual bool checkPathInternal(const std::string &abs_path, bool write_required,
                bool *write_allowed) = 0;
 
        // Ready-made implementation of `checkPathInternal` suitable for server-related uses
        static bool checkPathWithGamedef(lua_State *L, const std::string &abs_path,
                bool write_required, bool *write_allowed);
 
private:
        static int getThread(lua_State *L);
        // sets the environment to the table that's on top of the stack
        static void setLuaEnv(lua_State *L, int thread);
        // creates an empty Lua environment
        static void createEmptyEnv(lua_State *L);
        // replace "default files" (io.input/io.output) with /dev/null
        static void replaceDefaultFiles(lua_State *L);
 
        bool m_secure = false;
 
        // 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_g_collectgarbage(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);
 
        // reduced precision (for SSCSM)
        static int sl_os_clock(lua_State *L);
 
        static int sl_debug_getinfo(lua_State *L);
};