Skip to content
Permalink
Browse files

Refactor loading of Lua code with mod security

  • Loading branch information
sfan5 committed Nov 8, 2019
1 parent 17191a6 commit 5ab546f99bf3f438a8d19a3582798b5ab98476d6
Showing with 28 additions and 52 deletions.
  1. +26 −52 src/script/cpp_api/s_security.cpp
  2. +2 −0 src/script/cpp_api/s_security.h
@@ -372,14 +372,16 @@ bool ScriptApiSecurity::isSecure(lua_State *L)
return secure;
}


#define CHECK_FILE_ERR(ret, fp) \
if (ret) { \
lua_pushfstring(L, "%s: %s", path, strerror(errno)); \
if (fp) std::fclose(fp); \
return false; \
bool ScriptApiSecurity::safeLoadString(lua_State *L, const std::string &code, const char *chunk_name)
{
if (code.size() > 0 && code[0] == LUA_SIGNATURE[0]) {
lua_pushliteral(L, "Bytecode prohibited when mod security is enabled.");
return false;
}

if (luaL_loadbuffer(L, code.data(), code.size(), chunk_name))
return false;
return true;
}

bool ScriptApiSecurity::safeLoadFile(lua_State *L, const char *path, const char *display_name)
{
@@ -406,68 +408,49 @@ bool ScriptApiSecurity::safeLoadFile(lua_State *L, const char *path, const char
int c = std::getc(fp);
if (c == '#') {
// Skip the first line
while ((c = std::getc(fp)) != EOF && c != '\n');
if (c == '\n') c = std::getc(fp);
while ((c = std::getc(fp)) != EOF && c != '\n') {}
if (c == '\n')
std::getc(fp);
start = std::ftell(fp);
}

if (c == LUA_SIGNATURE[0]) {
lua_pushliteral(L, "Bytecode prohibited when mod security is enabled.");
std::fclose(fp);
if (path) {
delete [] chunk_name;
}
return false;
}

// Read the file
int ret = std::fseek(fp, 0, SEEK_END);
if (ret) {
lua_pushfstring(L, "%s: %s", path, strerror(errno));
std::fclose(fp);
if (path) {
std::fclose(fp);
delete [] chunk_name;
}
return false;
}

size_t size = std::ftell(fp) - start;
char *code = new char[size];
std::string code(size, '\0');
ret = std::fseek(fp, start, SEEK_SET);
if (ret) {
lua_pushfstring(L, "%s: %s", path, strerror(errno));
std::fclose(fp);
delete [] code;
if (path) {
std::fclose(fp);
delete [] chunk_name;
}
return false;
}

size_t num_read = std::fread(code, 1, size, fp);
if (path) {
size_t num_read = std::fread(&code[0], 1, size, fp);
if (path)
std::fclose(fp);
}
if (num_read != size) {
lua_pushliteral(L, "Error reading file to load.");
delete [] code;
if (path) {
if (path)
delete [] chunk_name;
}
return false;
}

if (luaL_loadbuffer(L, code, size, chunk_name)) {
delete [] code;
return false;
}

delete [] code;

if (path) {
bool result = safeLoadString(L, code, chunk_name);
if (path)
delete [] chunk_name;
}
return true;
return result;
}


@@ -628,14 +611,9 @@ int ScriptApiSecurity::sl_g_load(lua_State *L)
code += std::string(buf, len);
lua_pop(L, 1); // Pop return value
}
if (code[0] == LUA_SIGNATURE[0]) {
lua_pushnil(L);
lua_pushliteral(L, "Bytecode prohibited when mod security is enabled.");
return 2;
}
if (luaL_loadbuffer(L, code.data(), code.size(), chunk_name)) {
if (!safeLoadString(L, code, chunk_name)) {
lua_pushnil(L);
lua_insert(L, lua_gettop(L) - 1);
lua_insert(L, -2);
return 2;
}
return 1;
@@ -694,15 +672,11 @@ int ScriptApiSecurity::sl_g_loadstring(lua_State *L)

size_t size;
const char *code = lua_tolstring(L, 1, &size);
std::string code_s(code, size);

if (size > 0 && code[0] == LUA_SIGNATURE[0]) {
if (!safeLoadString(L, code_s, chunk_name)) {
lua_pushnil(L);
lua_pushliteral(L, "Bytecode prohibited when mod security is enabled.");
return 2;
}
if (luaL_loadbuffer(L, code, size, chunk_name)) {
lua_pushnil(L);
lua_insert(L, lua_gettop(L) - 1);
lua_insert(L, -2);
return 2;
}
return 1;
@@ -50,6 +50,8 @@ class ScriptApiSecurity : virtual public ScriptApiBase
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);
// Checks if mods are allowed to read (and optionally write) to the path

0 comments on commit 5ab546f

Please sign in to comment.
You can’t perform that action at this time.