3 Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU Lesser General Public License as published by
7 the Free Software Foundation; either version 2.1 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public License along
16 with this program; if not, write to the Free Software Foundation, Inc.,
17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
20 #include "cpp_api/s_security.h"
33 #define SECURE_API(lib, name) \
34 lua_pushcfunction(L, sl_##lib##_##name); \
35 lua_setfield(L, -2, #name);
38 static inline void copy_safe(lua_State *L, const char *list[], unsigned len, int from=-2, int to=-1)
40 if (from < 0) from = lua_gettop(L) + from + 1;
41 if (to < 0) to = lua_gettop(L) + to + 1;
42 for (unsigned i = 0; i < (len / sizeof(list[0])); i++) {
43 lua_getfield(L, from, list[i]);
44 lua_setfield(L, to, list[i]);
48 // Pushes the original version of a library function on the stack, from the old version
49 static inline void push_original(lua_State *L, const char *lib, const char *func)
51 lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_GLOBALS_BACKUP);
52 lua_getfield(L, -1, lib);
53 lua_remove(L, -2); // Remove globals_backup
54 lua_getfield(L, -1, func);
55 lua_remove(L, -2); // Remove lib
59 void ScriptApiSecurity::initializeSecurity()
61 static const char *whitelist[] = {
86 // Completely safe libraries
92 static const char *io_whitelist[] = {
99 static const char *os_whitelist[] = {
108 static const char *debug_whitelist[] = {
121 static const char *package_whitelist[] = {
128 static const char *jit_whitelist[] = {
142 lua_State *L = getStack();
144 // Backup globals to the registry
145 lua_getglobal(L, "_G");
146 lua_rawseti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_GLOBALS_BACKUP);
148 // Replace the global environment with an empty one
149 int thread = getThread(L);
151 setLuaEnv(L, thread);
154 lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_GLOBALS_BACKUP);
155 int old_globals = lua_gettop(L);
158 // Copy safe base functions
159 lua_getglobal(L, "_G");
160 copy_safe(L, whitelist, sizeof(whitelist));
162 // And replace unsafe ones
163 SECURE_API(g, dofile);
165 SECURE_API(g, loadfile);
166 SECURE_API(g, loadstring);
167 SECURE_API(g, require);
171 // Copy safe IO functions
172 lua_getfield(L, old_globals, "io");
174 copy_safe(L, io_whitelist, sizeof(io_whitelist));
176 // And replace unsafe ones
177 SECURE_API(io, open);
178 SECURE_API(io, input);
179 SECURE_API(io, output);
180 SECURE_API(io, lines);
182 lua_setglobal(L, "io");
183 lua_pop(L, 1); // Pop old IO
186 // Copy safe OS functions
187 lua_getfield(L, old_globals, "os");
189 copy_safe(L, os_whitelist, sizeof(os_whitelist));
191 // And replace unsafe ones
192 SECURE_API(os, remove);
193 SECURE_API(os, rename);
195 lua_setglobal(L, "os");
196 lua_pop(L, 1); // Pop old OS
199 // Copy safe debug functions
200 lua_getfield(L, old_globals, "debug");
202 copy_safe(L, debug_whitelist, sizeof(debug_whitelist));
203 lua_setglobal(L, "debug");
204 lua_pop(L, 1); // Pop old debug
207 // Copy safe package fields
208 lua_getfield(L, old_globals, "package");
210 copy_safe(L, package_whitelist, sizeof(package_whitelist));
211 lua_setglobal(L, "package");
212 lua_pop(L, 1); // Pop old package
215 // Copy safe jit functions, if they exist
216 lua_getfield(L, -1, "jit");
217 if (!lua_isnil(L, -1)) {
219 copy_safe(L, jit_whitelist, sizeof(jit_whitelist));
220 lua_setglobal(L, "jit");
222 lua_pop(L, 1); // Pop old jit
225 lua_pop(L, 1); // Pop globals_backup
228 void ScriptApiSecurity::initializeSecurityClient()
230 static const char *whitelist[] = {
254 // Completely safe libraries
260 static const char *os_whitelist[] = {
267 static const char *debug_whitelist[] = {
272 static const char *jit_whitelist[] = {
287 lua_State *L = getStack();
288 int thread = getThread(L);
290 // create an empty environment
293 // Copy safe base functions
294 lua_getglobal(L, "_G");
295 lua_getfield(L, -2, "_G");
296 copy_safe(L, whitelist, sizeof(whitelist));
298 // And replace unsafe ones
299 SECURE_API(g, dofile);
301 SECURE_API(g, loadfile);
302 SECURE_API(g, loadstring);
303 SECURE_API(g, require);
308 // Copy safe OS functions
309 lua_getglobal(L, "os");
311 copy_safe(L, os_whitelist, sizeof(os_whitelist));
312 lua_setfield(L, -3, "os");
313 lua_pop(L, 1); // Pop old OS
316 // Copy safe debug functions
317 lua_getglobal(L, "debug");
319 copy_safe(L, debug_whitelist, sizeof(debug_whitelist));
320 lua_setfield(L, -3, "debug");
321 lua_pop(L, 1); // Pop old debug
324 // Copy safe jit functions, if they exist
325 lua_getglobal(L, "jit");
327 copy_safe(L, jit_whitelist, sizeof(jit_whitelist));
328 lua_setfield(L, -3, "jit");
329 lua_pop(L, 1); // Pop old jit
332 // Set the environment to the one we created earlier
333 setLuaEnv(L, thread);
336 int ScriptApiSecurity::getThread(lua_State *L)
338 #if LUA_VERSION_NUM <= 501
339 int is_main = lua_pushthread(L); // Push the main thread
340 FATAL_ERROR_IF(!is_main, "Security: ScriptApi's Lua state "
341 "isn't the main Lua thread!");
342 return lua_gettop(L);
347 void ScriptApiSecurity::createEmptyEnv(lua_State *L)
349 lua_newtable(L); // Create new environment
350 lua_pushvalue(L, -1);
351 lua_setfield(L, -2, "_G"); // Create the _G loop
354 void ScriptApiSecurity::setLuaEnv(lua_State *L, int thread)
356 #if LUA_VERSION_NUM >= 502 // Lua >= 5.2
357 // Set the global environment
358 lua_rawseti(L, LUA_REGISTRYINDEX, LUA_RIDX_GLOBALS);
360 // Set the environment of the main thread
361 FATAL_ERROR_IF(!lua_setfenv(L, thread), "Security: Unable to set "
362 "environment of the main Lua thread!");
363 lua_pop(L, 1); // Pop thread
367 bool ScriptApiSecurity::isSecure(lua_State *L)
369 lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_GLOBALS_BACKUP);
370 bool secure = !lua_isnil(L, -1);
376 #define CHECK_FILE_ERR(ret, fp) \
378 lua_pushfstring(L, "%s: %s", path, strerror(errno)); \
379 if (fp) std::fclose(fp); \
384 bool ScriptApiSecurity::safeLoadFile(lua_State *L, const char *path, const char *display_name)
392 chunk_name = const_cast<char *>("=stdin");
394 fp = fopen(path, "rb");
396 lua_pushfstring(L, "%s: %s", path, strerror(errno));
399 chunk_name = new char[strlen(display_name) + 2];
401 chunk_name[1] = '\0';
402 strcat(chunk_name, display_name);
406 int c = std::getc(fp);
408 // Skip the first line
409 while ((c = std::getc(fp)) != EOF && c != '\n');
410 if (c == '\n') c = std::getc(fp);
411 start = std::ftell(fp);
414 if (c == LUA_SIGNATURE[0]) {
415 lua_pushliteral(L, "Bytecode prohibited when mod security is enabled.");
418 delete [] chunk_name;
424 int ret = std::fseek(fp, 0, SEEK_END);
426 lua_pushfstring(L, "%s: %s", path, strerror(errno));
429 delete [] chunk_name;
434 size_t size = std::ftell(fp) - start;
435 char *code = new char[size];
436 ret = std::fseek(fp, start, SEEK_SET);
438 lua_pushfstring(L, "%s: %s", path, strerror(errno));
442 delete [] chunk_name;
447 size_t num_read = std::fread(code, 1, size, fp);
451 if (num_read != size) {
452 lua_pushliteral(L, "Error reading file to load.");
455 delete [] chunk_name;
460 if (luaL_loadbuffer(L, code, size, chunk_name)) {
468 delete [] chunk_name;
474 bool ScriptApiSecurity::checkPath(lua_State *L, const char *path,
475 bool write_required, bool *write_allowed)
478 *write_allowed = false;
480 std::string str; // Transient
482 std::string abs_path = fs::AbsolutePath(path);
484 if (!abs_path.empty()) {
485 // Don't allow accessing the settings file
486 str = fs::AbsolutePath(g_settings_path);
487 if (str == abs_path) return false;
490 // If we couldn't find the absolute path (path doesn't exist) then
491 // try removing the last components until it works (to allow
492 // non-existent files/folders for mkdir).
493 std::string cur_path = path;
495 while (abs_path.empty() && !cur_path.empty()) {
496 std::string component;
497 cur_path = fs::RemoveLastPathComponent(cur_path, &component);
498 if (component == "..") {
499 // Parent components can't be allowed or we could allow something like
500 // /home/user/minetest/worlds/foo/noexist/../../../../../../etc/passwd.
501 // If we have previous non-relative elements in the path we might be
502 // able to remove them so that things like worlds/foo/noexist/../auth.txt
503 // could be allowed, but those paths will be interpreted as nonexistent
504 // by the operating system anyways.
507 removed.append(component).append(removed.empty() ? "" : DIR_DELIM + removed);
508 abs_path = fs::AbsolutePath(cur_path);
510 if (abs_path.empty())
512 // Add the removed parts back so that you can't, eg, create a
513 // directory in worldmods if worldmods doesn't exist.
514 if (!removed.empty())
515 abs_path += DIR_DELIM + removed;
517 // Get server from registry
518 lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_SCRIPTAPI);
519 ScriptApiBase *script = (ScriptApiBase *) lua_touserdata(L, -1);
521 const IGameDef *gamedef = script->getGameDef();
526 lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
527 if (lua_isstring(L, -1)) {
528 std::string mod_name = lua_tostring(L, -1);
530 // Builtin can access anything
531 if (mod_name == BUILTIN_MOD_NAME) {
532 if (write_allowed) *write_allowed = true;
536 // Allow paths in mod path
537 // Don't bother if write access isn't important, since it will be handled later
538 if (write_required || write_allowed != NULL) {
539 const ModSpec *mod = gamedef->getModSpec(mod_name);
541 str = fs::AbsolutePath(mod->path);
542 if (!str.empty() && fs::PathStartsWith(abs_path, str)) {
543 if (write_allowed) *write_allowed = true;
549 lua_pop(L, 1); // Pop mod name
551 // Allow read-only access to all mod directories
552 if (!write_required) {
553 const std::vector<ModSpec> &mods = gamedef->getMods();
554 for (const ModSpec &mod : mods) {
555 str = fs::AbsolutePath(mod.path);
556 if (!str.empty() && fs::PathStartsWith(abs_path, str)) {
562 str = fs::AbsolutePath(gamedef->getWorldPath());
564 // Don't allow access to other paths in the world mod/game path.
565 // These have to be blocked so you can't override a trusted mod
566 // by creating a mod with the same name in a world mod directory.
567 // We add to the absolute path of the world instead of getting
568 // the absolute paths directly because that won't work if they
570 if (fs::PathStartsWith(abs_path, str + DIR_DELIM + "worldmods") ||
571 fs::PathStartsWith(abs_path, str + DIR_DELIM + "game")) {
574 // Allow all other paths in world path
575 if (fs::PathStartsWith(abs_path, str)) {
576 if (write_allowed) *write_allowed = true;
581 // Default to disallowing
586 int ScriptApiSecurity::sl_g_dofile(lua_State *L)
588 int nret = sl_g_loadfile(L);
591 // code after this function isn't executed
593 int top_precall = lua_gettop(L);
594 lua_call(L, 0, LUA_MULTRET);
595 // Return number of arguments returned by the function,
596 // adjusting for the function being poped.
597 return lua_gettop(L) - (top_precall - 1);
601 int ScriptApiSecurity::sl_g_load(lua_State *L)
606 const char *chunk_name = "=(load)";
608 luaL_checktype(L, 1, LUA_TFUNCTION);
609 if (!lua_isnone(L, 2)) {
610 luaL_checktype(L, 2, LUA_TSTRING);
611 chunk_name = lua_tostring(L, 2);
617 int t = lua_type(L, -1);
622 if (t != LUA_TSTRING) {
624 lua_pushliteral(L, "Loader didn't return a string");
627 buf = lua_tolstring(L, -1, &len);
628 code += std::string(buf, len);
629 lua_pop(L, 1); // Pop return value
631 if (code[0] == LUA_SIGNATURE[0]) {
633 lua_pushliteral(L, "Bytecode prohibited when mod security is enabled.");
636 if (luaL_loadbuffer(L, code.data(), code.size(), chunk_name)) {
638 lua_insert(L, lua_gettop(L) - 1);
645 int ScriptApiSecurity::sl_g_loadfile(lua_State *L)
648 lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_SCRIPTAPI);
649 ScriptApiBase *script = (ScriptApiBase *) lua_touserdata(L, -1);
652 if (script->getType() == ScriptingType::Client) {
653 std:: string display_path = lua_tostring(L, 1);
654 const std::string *path = script->getClient()->getModFile(display_path);
656 std::string error_msg = "Coudln't find script called:" + display_path;
658 lua_pushstring(L, error_msg.c_str());
661 if (!safeLoadFile(L, path->c_str(), display_path.c_str())) {
669 const char *path = NULL;
670 if (lua_isstring(L, 1)) {
671 path = lua_tostring(L, 1);
672 CHECK_SECURE_PATH_INTERNAL(L, path, false, NULL);
675 if (!safeLoadFile(L, path)) {
685 int ScriptApiSecurity::sl_g_loadstring(lua_State *L)
687 const char *chunk_name = "=(load)";
689 luaL_checktype(L, 1, LUA_TSTRING);
690 if (!lua_isnone(L, 2)) {
691 luaL_checktype(L, 2, LUA_TSTRING);
692 chunk_name = lua_tostring(L, 2);
696 const char *code = lua_tolstring(L, 1, &size);
698 if (size > 0 && code[0] == LUA_SIGNATURE[0]) {
700 lua_pushliteral(L, "Bytecode prohibited when mod security is enabled.");
703 if (luaL_loadbuffer(L, code, size, chunk_name)) {
705 lua_insert(L, lua_gettop(L) - 1);
712 int ScriptApiSecurity::sl_g_require(lua_State *L)
714 lua_pushliteral(L, "require() is disabled when mod security is on.");
719 int ScriptApiSecurity::sl_io_open(lua_State *L)
721 bool with_mode = lua_gettop(L) > 1;
723 luaL_checktype(L, 1, LUA_TSTRING);
724 const char *path = lua_tostring(L, 1);
726 bool write_requested = false;
728 luaL_checktype(L, 2, LUA_TSTRING);
729 const char *mode = lua_tostring(L, 2);
730 write_requested = strchr(mode, 'w') != NULL ||
731 strchr(mode, '+') != NULL ||
732 strchr(mode, 'a') != NULL;
734 CHECK_SECURE_PATH_INTERNAL(L, path, write_requested, NULL);
736 push_original(L, "io", "open");
742 lua_call(L, with_mode ? 2 : 1, 2);
747 int ScriptApiSecurity::sl_io_input(lua_State *L)
749 if (lua_isstring(L, 1)) {
750 const char *path = lua_tostring(L, 1);
751 CHECK_SECURE_PATH_INTERNAL(L, path, false, NULL);
754 push_original(L, "io", "input");
761 int ScriptApiSecurity::sl_io_output(lua_State *L)
763 if (lua_isstring(L, 1)) {
764 const char *path = lua_tostring(L, 1);
765 CHECK_SECURE_PATH_INTERNAL(L, path, true, NULL);
768 push_original(L, "io", "output");
775 int ScriptApiSecurity::sl_io_lines(lua_State *L)
777 if (lua_isstring(L, 1)) {
778 const char *path = lua_tostring(L, 1);
779 CHECK_SECURE_PATH_INTERNAL(L, path, false, NULL);
782 int top_precall = lua_gettop(L);
783 push_original(L, "io", "lines");
785 lua_call(L, 1, LUA_MULTRET);
786 // Return number of arguments returned by the function,
787 // adjusting for the function being poped.
788 return lua_gettop(L) - top_precall;
792 int ScriptApiSecurity::sl_os_rename(lua_State *L)
794 luaL_checktype(L, 1, LUA_TSTRING);
795 const char *path1 = lua_tostring(L, 1);
796 CHECK_SECURE_PATH_INTERNAL(L, path1, true, NULL);
798 luaL_checktype(L, 2, LUA_TSTRING);
799 const char *path2 = lua_tostring(L, 2);
800 CHECK_SECURE_PATH_INTERNAL(L, path2, true, NULL);
802 push_original(L, "os", "rename");
810 int ScriptApiSecurity::sl_os_remove(lua_State *L)
812 luaL_checktype(L, 1, LUA_TSTRING);
813 const char *path = lua_tostring(L, 1);
814 CHECK_SECURE_PATH_INTERNAL(L, path, true, NULL);
816 push_original(L, "os", "remove");