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Refactor how script api reads current mod name

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This is to prevent future mistakes and make it clearer whether
the mod name can be trusted depending on how it is retrieved.
This commit is contained in:
sfan5 2024-02-14 13:29:53 +01:00
parent cb5fa56e17
commit ce97210eb1
8 changed files with 88 additions and 78 deletions
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41
src/script/cpp_api/s_base.cpp
View File

@ -179,6 +179,7 @@ int ScriptApiBase::luaPanic(lua_State *L)
return 0;
}
#ifndef SERVER
void ScriptApiBase::clientOpenLibs(lua_State *L)
{
static const std::vector<std::pair<std::string, lua_CFunction>> m_libs = {
@ -199,6 +200,7 @@ void ScriptApiBase::clientOpenLibs(lua_State *L)
lua_call(L, 1, 0);
}
}
#endif
void ScriptApiBase::checkSetByBuiltin()
{
@ -223,6 +225,45 @@ void ScriptApiBase::checkSetByBuiltin()
}
}
std::string ScriptApiBase::getCurrentModNameInsecure(lua_State *L)
{
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
auto ret = lua_isstring(L, -1) ? readParam<std::string>(L, -1) : "";
lua_pop(L, 1);
return ret;
}
std::string ScriptApiBase::getCurrentModName(lua_State *L)
{
auto script = ModApiBase::getScriptApiBase(L);
if (script->getType() == ScriptingType::Async ||
script->getType() == ScriptingType::Emerge)
{
// As a precaution never return a "secure" mod name in the async and
// emerge environment, because these currently do not track mod origins
// in a spoof-safe way (see l_register_async_dofile and l_register_mapgen_script).
return "";
}
// We have to make sure that this function is being called directly by
// a mod, otherwise a malicious mod could override a function and
// steal its return value. (e.g. request_insecure_environment)
lua_Debug info;
// Make sure there's only one item below this function on the stack...
if (lua_getstack(L, 2, &info))
return "";
FATAL_ERROR_IF(!lua_getstack(L, 1, &info), "lua_getstack() failed");
FATAL_ERROR_IF(!lua_getinfo(L, "S", &info), "lua_getinfo() failed");
// ...and that that item is the main file scope.
if (strcmp(info.what, "main") != 0)
return "";
// at this point we can trust this value:
return getCurrentModNameInsecure(L);
}
void ScriptApiBase::loadMod(const std::string &script_path,
const std::string &mod_name)
{

20
src/script/cpp_api/s_base.h
View File

@ -110,13 +110,29 @@ public:
Client* getClient();
#endif
// IMPORTANT: these cannot be used for any security-related uses, they exist
// only to enrich error messages
// IMPORTANT: These cannot be used for any security-related uses, they exist
// only to enrich error messages.
const std::string &getOrigin() { return m_last_run_mod; }
void setOriginDirect(const char *origin);
void setOriginFromTableRaw(int index, const char *fxn);
// Returns the currently running mod, only during init time.
// The reason this is "insecure" is that mods can mess with each others code,
// so the boundary of who is responsible is fuzzy.
// Note: checking this against BUILTIN_MOD_NAME is always safe (not spoofable).
// returns "" on error
static std::string getCurrentModNameInsecure(lua_State *L);
// Returns the currently running mod, only during init time.
// This checks the Lua stack to only permit direct calls in the file
// scope. That way it is assured that it's really the mod it claims to be.
// returns "" on error
static std::string getCurrentModName(lua_State *L);
#ifdef SERVER
inline void clientOpenLibs(lua_State *L) { assert(false); }
#else
void clientOpenLibs(lua_State *L);
#endif
// Check things that should be set by the builtin mod.
void checkSetByBuiltin();

29
src/script/cpp_api/s_security.cpp
View File

@ -555,10 +555,9 @@ bool ScriptApiSecurity::checkPath(lua_State *L, const char *path,
return false;
// Get mod name
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
if (lua_isstring(L, -1)) {
std::string mod_name = readParam<std::string>(L, -1);
// FIXME: insecure = problem here?
std::string mod_name = ScriptApiBase::getCurrentModNameInsecure(L);
if (!mod_name.empty()) {
// Builtin can access anything
if (mod_name == BUILTIN_MOD_NAME) {
if (write_allowed) *write_allowed = true;
@ -578,7 +577,6 @@ bool ScriptApiSecurity::checkPath(lua_State *L, const char *path,
}
}
}
lua_pop(L, 1); // Pop mod name
// Allow read-only access to game directory
if (!write_required) {
@ -629,26 +627,9 @@ bool ScriptApiSecurity::checkWhitelisted(lua_State *L, const std::string &settin
{
assert(str_starts_with(setting, "secure."));
// We have to make sure that this function is being called directly by
// a mod, otherwise a malicious mod could override this function and
// steal its return value.
lua_Debug info;
// Make sure there's only one item below this function on the stack...
if (lua_getstack(L, 2, &info))
std::string mod_name = ScriptApiBase::getCurrentModName(L);
if (mod_name.empty())
return false;
FATAL_ERROR_IF(!lua_getstack(L, 1, &info), "lua_getstack() failed");
FATAL_ERROR_IF(!lua_getinfo(L, "S", &info), "lua_getinfo() failed");
// ...and that that item is the main file scope.
if (strcmp(info.what, "main") != 0)
return false;
// Mod must be listed in secure.http_mods or secure.trusted_mods
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
if (!lua_isstring(L, -1))
return false;
std::string mod_name = readParam<std::string>(L, -1);
std::string value = g_settings->get(setting);
value.erase(std::remove(value.begin(), value.end(), ' '), value.end());

3
src/script/lua_api/l_base.cpp
View File

@ -82,8 +82,7 @@ EmergeThread *ModApiBase::getEmergeThread(lua_State *L)
std::string ModApiBase::getCurrentModPath(lua_State *L)
{
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
std::string current_mod_name = readParam<std::string>(L, -1, "");
std::string current_mod_name = ScriptApiBase::getCurrentModNameInsecure(L);
if (current_mod_name.empty())
return ".";

32
src/script/lua_api/l_client.cpp
View File

@ -62,7 +62,11 @@ const static CSMFlagDesc flagdesc_csm_restriction[] = {
// get_current_modname()
int ModApiClient::l_get_current_modname(lua_State *L)
{
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
std::string s = ScriptApiBase::getCurrentModNameInsecure(L);
if (!s.empty())
lua_pushstring(L, s.c_str());
else
lua_pushnil(L);
return 1;
}
@ -76,30 +80,6 @@ int ModApiClient::l_get_modpath(lua_State *L)
return 1;
}
// get_last_run_mod()
int ModApiClient::l_get_last_run_mod(lua_State *L)
{
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
std::string current_mod = readParam<std::string>(L, -1, "");
if (current_mod.empty()) {
lua_pop(L, 1);
lua_pushstring(L, getScriptApiBase(L)->getOrigin().c_str());
}
return 1;
}
// set_last_run_mod(modname)
int ModApiClient::l_set_last_run_mod(lua_State *L)
{
if (!lua_isstring(L, 1))
return 0;
const char *mod = lua_tostring(L, 1);
getScriptApiBase(L)->setOriginDirect(mod);
lua_pushboolean(L, true);
return 1;
}
// print(text)
int ModApiClient::l_print(lua_State *L)
{
@ -367,8 +347,6 @@ void ModApiClient::Initialize(lua_State *L, int top)
API_FCT(send_chat_message);
API_FCT(clear_out_chat_queue);
API_FCT(get_player_names);
API_FCT(set_last_run_mod);
API_FCT(get_last_run_mod);
API_FCT(show_formspec);
API_FCT(send_respawn);
API_FCT(gettext);

6
src/script/lua_api/l_client.h
View File

@ -60,12 +60,6 @@ private:
// gettext(text)
static int l_gettext(lua_State *L);
// get_last_run_mod(n)
static int l_get_last_run_mod(lua_State *L);
// set_last_run_mod(modname)
static int l_set_last_run_mod(lua_State *L);
// get_node(pos)
static int l_get_node_or_nil(lua_State *L);

22
src/script/lua_api/l_server.cpp
View File

@ -440,7 +440,11 @@ int ModApiServer::l_show_formspec(lua_State *L)
int ModApiServer::l_get_current_modname(lua_State *L)
{
NO_MAP_LOCK_REQUIRED;
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
std::string s = ScriptApiBase::getCurrentModNameInsecure(L);
if (!s.empty())
lua_pushstring(L, s.c_str());
else
lua_pushnil(L);
return 1;
}
@ -656,11 +660,9 @@ int ModApiServer::l_register_async_dofile(lua_State *L)
std::string path = readParam<std::string>(L, 1);
CHECK_SECURE_PATH(L, path.c_str(), false);
// Find currently running mod name (only at init time)
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
if (!lua_isstring(L, -1))
return 0;
std::string modname = readParam<std::string>(L, -1);
std::string modname = ScriptApiBase::getCurrentModNameInsecure(L);
if (modname.empty())
throw ModError("cannot determine mod name");
getServer(L)->m_async_init_files.emplace_back(modname, path);
lua_pushboolean(L, true);
@ -675,11 +677,9 @@ int ModApiServer::l_register_mapgen_script(lua_State *L)
std::string path = readParam<std::string>(L, 1);
CHECK_SECURE_PATH(L, path.c_str(), false);
// Find currently running mod name (only at init time)
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
if (!lua_isstring(L, -1))
return 0;
std::string modname = readParam<std::string>(L, -1);
std::string modname = ScriptApiBase::getCurrentModNameInsecure(L);
if (modname.empty())
throw ModError("cannot determine mod name");
getServer(L)->m_mapgen_init_files.emplace_back(modname, path);
lua_pushboolean(L, true);

13
src/script/lua_api/l_util.cpp
View File

@ -632,12 +632,10 @@ int ModApiUtil::l_get_last_run_mod(lua_State *L)
{
NO_MAP_LOCK_REQUIRED;
lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
std::string current_mod = readParam<std::string>(L, -1, "");
if (current_mod.empty()) {
lua_pop(L, 1);
lua_pushstring(L, getScriptApiBase(L)->getOrigin().c_str());
}
std::string current_mod = ScriptApiBase::getCurrentModNameInsecure(L);
if (current_mod.empty())
current_mod = getScriptApiBase(L)->getOrigin();
lua_pushstring(L, current_mod.c_str());
return 1;
}
@ -735,6 +733,9 @@ void ModApiUtil::InitializeClient(lua_State *L, int top)
API_FCT(colorspec_to_colorstring);
API_FCT(colorspec_to_bytes);
API_FCT(get_last_run_mod);
API_FCT(set_last_run_mod);
API_FCT(urlencode);
LuaSettings::create(L, g_settings, g_settings_path);