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Use numeric indices and raw table access with LUA_REGISTRYINDEX
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kahrl authored and est31 committed Aug 26, 2015
1 parent 34b7a14 commit 8658c8d
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Showing 7 changed files with 36 additions and 16 deletions.
21 changes: 21 additions & 0 deletions src/script/common/c_internal.h
Expand Up @@ -34,6 +34,27 @@ extern "C" {

#include "common/c_types.h"


/*
Define our custom indices into the Lua registry table.
Lua 5.2 and above define the LUA_RIDX_LAST macro. Only numbers above that
may be used for custom indices, anything else is reserved.
Lua 5.1 / LuaJIT do not use any numeric indices (only string indices),
so we can use numeric indices freely.
*/
#ifdef LUA_RIDX_LAST
#define CUSTOM_RIDX_BASE ((LUA_RIDX_LAST)+1)
#else
#define CUSTOM_RIDX_BASE 1
#endif

#define CUSTOM_RIDX_SCRIPTAPI (CUSTOM_RIDX_BASE)
#define CUSTOM_RIDX_GLOBALS_BACKUP (CUSTOM_RIDX_BASE + 1)
#define CUSTOM_RIDX_CURRENT_MOD_NAME (CUSTOM_RIDX_BASE + 2)


#define PCALL_RESL(L, RES) do { \
int result_ = (RES); \
if (result_ != 0) { \
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6 changes: 3 additions & 3 deletions src/script/cpp_api/s_base.cpp
Expand Up @@ -52,13 +52,13 @@ class ModNameStorer
{
// Store current mod name in registry
lua_pushstring(L, mod_name.c_str());
lua_setfield(L, LUA_REGISTRYINDEX, SCRIPT_MOD_NAME_FIELD);
lua_rawseti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
}
~ModNameStorer()
{
// Clear current mod name from registry
lua_pushnil(L);
lua_setfield(L, LUA_REGISTRYINDEX, SCRIPT_MOD_NAME_FIELD);
lua_rawseti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
}
};

Expand All @@ -84,7 +84,7 @@ ScriptApiBase::ScriptApiBase()

// Make the ScriptApiBase* accessible to ModApiBase
lua_pushlightuserdata(m_luastack, this);
lua_setfield(m_luastack, LUA_REGISTRYINDEX, "scriptapi");
lua_rawseti(m_luastack, LUA_REGISTRYINDEX, CUSTOM_RIDX_SCRIPTAPI);

// If we are using LuaJIT add a C++ wrapper function to catch
// exceptions thrown in Lua -> C++ calls
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1 change: 0 additions & 1 deletion src/script/cpp_api/s_base.h
Expand Up @@ -36,7 +36,6 @@ extern "C" {
#define SCRIPTAPI_LOCK_DEBUG
#define SCRIPTAPI_DEBUG

#define SCRIPT_MOD_NAME_FIELD "current_mod_name"
// MUST be an invalid mod name so that mods can't
// use that name to bypass security!
#define BUILTIN_MOD_NAME "*builtin*"
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12 changes: 6 additions & 6 deletions src/script/cpp_api/s_security.cpp
Expand Up @@ -47,7 +47,7 @@ static inline void copy_safe(lua_State *L, const char *list[], unsigned len, int
// Pushes the original version of a library function on the stack, from the old version
static inline void push_original(lua_State *L, const char *lib, const char *func)
{
lua_getfield(L, LUA_REGISTRYINDEX, "globals_backup");
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_GLOBALS_BACKUP);
lua_getfield(L, -1, lib);
lua_remove(L, -2); // Remove globals_backup
lua_getfield(L, -1, func);
Expand Down Expand Up @@ -143,7 +143,7 @@ void ScriptApiSecurity::initializeSecurity()

// Backup globals to the registry
lua_getglobal(L, "_G");
lua_setfield(L, LUA_REGISTRYINDEX, "globals_backup");
lua_rawseti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_GLOBALS_BACKUP);

// Replace the global environment with an empty one
#if LUA_VERSION_NUM <= 501
Expand All @@ -165,7 +165,7 @@ void ScriptApiSecurity::initializeSecurity()
#endif

// Get old globals
lua_getfield(L, LUA_REGISTRYINDEX, "globals_backup");
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_GLOBALS_BACKUP);
int old_globals = lua_gettop(L);


Expand Down Expand Up @@ -241,7 +241,7 @@ void ScriptApiSecurity::initializeSecurity()

bool ScriptApiSecurity::isSecure(lua_State *L)
{
lua_getfield(L, LUA_REGISTRYINDEX, "globals_backup");
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_GLOBALS_BACKUP);
bool secure = !lua_isnil(L, -1);
lua_pop(L, 1);
return secure;
Expand Down Expand Up @@ -356,15 +356,15 @@ bool ScriptApiSecurity::checkPath(lua_State *L, const char *path)
if (!removed.empty()) abs_path += DIR_DELIM + removed;

// Get server from registry
lua_getfield(L, LUA_REGISTRYINDEX, "scriptapi");
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_SCRIPTAPI);
ScriptApiBase *script = (ScriptApiBase *) lua_touserdata(L, -1);
lua_pop(L, 1);
const Server *server = script->getServer();

if (!server) return false;

// Get mod name
lua_getfield(L, LUA_REGISTRYINDEX, SCRIPT_MOD_NAME_FIELD);
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
if (lua_isstring(L, -1)) {
std::string mod_name = lua_tostring(L, -1);

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4 changes: 2 additions & 2 deletions src/script/lua_api/l_base.cpp
Expand Up @@ -26,7 +26,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
ScriptApiBase *ModApiBase::getScriptApiBase(lua_State *L)
{
// Get server from registry
lua_getfield(L, LUA_REGISTRYINDEX, "scriptapi");
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_SCRIPTAPI);
ScriptApiBase *sapi_ptr = (ScriptApiBase*) lua_touserdata(L, -1);
lua_pop(L, 1);
return sapi_ptr;
Expand All @@ -49,7 +49,7 @@ GUIEngine *ModApiBase::getGuiEngine(lua_State *L)

std::string ModApiBase::getCurrentModPath(lua_State *L)
{
lua_getfield(L, LUA_REGISTRYINDEX, SCRIPT_MOD_NAME_FIELD);
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
const char *current_mod_name = lua_tostring(L, -1);
if (!current_mod_name)
return ".";
Expand Down
4 changes: 2 additions & 2 deletions src/script/lua_api/l_server.cpp
Expand Up @@ -345,7 +345,7 @@ int ModApiServer::l_show_formspec(lua_State *L)
int ModApiServer::l_get_current_modname(lua_State *L)
{
NO_MAP_LOCK_REQUIRED;
lua_getfield(L, LUA_REGISTRYINDEX, SCRIPT_MOD_NAME_FIELD);
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
return 1;
}

Expand Down Expand Up @@ -442,7 +442,7 @@ int ModApiServer::l_notify_authentication_modified(lua_State *L)
int ModApiServer::l_get_last_run_mod(lua_State *L)
{
NO_MAP_LOCK_REQUIRED;
lua_getfield(L, LUA_REGISTRYINDEX, SCRIPT_MOD_NAME_FIELD);
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
const char *current_mod = lua_tostring(L, -1);
if (current_mod == NULL || current_mod[0] == '\0') {
lua_pop(L, 1);
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4 changes: 2 additions & 2 deletions src/script/lua_api/l_util.cpp
Expand Up @@ -371,7 +371,7 @@ int ModApiUtil::l_request_insecure_environment(lua_State *L)
lua_getglobal(L, "_G");
return 1;
}
lua_getfield(L, LUA_REGISTRYINDEX, SCRIPT_MOD_NAME_FIELD);
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
if (!lua_isstring(L, -1)) {
lua_pushnil(L);
return 1;
Expand All @@ -383,7 +383,7 @@ int ModApiUtil::l_request_insecure_environment(lua_State *L)
lua_pushnil(L);
return 1;
}
lua_getfield(L, LUA_REGISTRYINDEX, "globals_backup");
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_GLOBALS_BACKUP);
return 1;
}

Expand Down

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