Refactor trusted mod checking code

Author: sfan5

src/script/cpp_api/s_security.cpp

@@ -27,6 +27,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include <cerrno>
 #include <string>
+#include <algorithm>
 #include <iostream>
 
 
@@ -604,6 +605,38 @@ bool ScriptApiSecurity::checkPath(lua_State *L, const char *path,
 	return false;
 }
 
+bool ScriptApiSecurity::checkWhitelisted(lua_State *L, const std::string &setting)
+{
+	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))
+		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());
+	auto mod_list = str_split(value, ',');
+
+	return CONTAINS(mod_list, mod_name);
+}
+
 
 int ScriptApiSecurity::sl_g_dofile(lua_State *L)
 {

src/script/cpp_api/s_security.h

@@ -40,11 +40,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 class ScriptApiSecurity : virtual public ScriptApiBase
 {
 public:
-	int getThread(lua_State *L);
-	// creates an empty Lua environment
-	void createEmptyEnv(lua_State *L);
-	// sets the enviroment to the table thats on top of the stack
-	void setLuaEnv(lua_State *L, int thread);
 	// Sets up security on the ScriptApi's Lua state
 	void initializeSecurity();
 	void initializeSecurityClient();
@@ -57,8 +52,17 @@ class ScriptApiSecurity : virtual public ScriptApiBase
 	// Checks if mods are allowed to read (and optionally write) to the path
 	static bool checkPath(lua_State *L, const char *path, bool write_required,
 			bool *write_allowed=NULL);
+	// Check if mod is whitelisted in the given setting
+	// This additionally checks that the mod's main file scope is executing.
+	static bool checkWhitelisted(lua_State *L, const std::string &setting);
 
 private:
+	int getThread(lua_State *L);
+	// sets the enviroment to the table thats on top of the stack
+	void setLuaEnv(lua_State *L, int thread);
+	// creates an empty Lua environment
+	void createEmptyEnv(lua_State *L);
+
 	// Syntax: "sl_" <Library name or 'g' (global)> '_' <Function name>
 	// (sl stands for Secure Lua)
 

src/script/lua_api/l_http.cpp

@@ -21,14 +21,13 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "common/c_converter.h"
 #include "common/c_content.h"
 #include "lua_api/l_http.h"
+#include "cpp_api/s_security.h"
 #include "httpfetch.h"
 #include "settings.h"
 #include "debug.h"
 #include "log.h"
 
-#include <algorithm>
 #include <iomanip>
-#include <cctype>
 
 #define HTTP_API(name) \
 	lua_pushstring(L, #name); \
@@ -181,40 +180,8 @@ int ModApiHttp::l_request_http_api(lua_State *L)
 {
 	NO_MAP_LOCK_REQUIRED;
 
-	// 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)) {
-		return 0;
-	}
-	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 0;
-	}
-
-	// 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 0;
-	}
-
-	std::string mod_name = readParam<std::string>(L, -1);
-	std::string http_mods = g_settings->get("secure.http_mods");
-	http_mods.erase(std::remove(http_mods.begin(), http_mods.end(), ' '), http_mods.end());
-	std::vector<std::string> mod_list_http = str_split(http_mods, ',');
-
-	std::string trusted_mods = g_settings->get("secure.trusted_mods");
-	trusted_mods.erase(std::remove(trusted_mods.begin(), trusted_mods.end(), ' '), trusted_mods.end());
-	std::vector<std::string> mod_list_trusted = str_split(trusted_mods, ',');
-
-	mod_list_http.insert(mod_list_http.end(), mod_list_trusted.begin(), mod_list_trusted.end());
-	if (std::find(mod_list_http.begin(), mod_list_http.end(), mod_name) == mod_list_http.end()) {
+	if (!ScriptApiSecurity::checkWhitelisted(L, "secure.http_mods") &&
+			!ScriptApiSecurity::checkWhitelisted(L, "secure.trusted_mods")) {
 		lua_pushnil(L);
 		return 1;
 	}

src/script/lua_api/l_util.cpp

@@ -41,7 +41,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "util/hex.h"
 #include "util/sha1.h"
 #include "util/png.h"
-#include <algorithm>
 #include <cstdio>
 
 // log([level,] text)
@@ -444,36 +443,7 @@ int ModApiUtil::l_request_insecure_environment(lua_State *L)
 		return 1;
 	}
 
-	// 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)) {
-		return 0;
-	}
-	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 0;
-	}
-
-	// Get mod name
-	lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
-	if (!lua_isstring(L, -1)) {
-		return 0;
-	}
-
-	// Check secure.trusted_mods
-	std::string mod_name = readParam<std::string>(L, -1);
-	std::string trusted_mods = g_settings->get("secure.trusted_mods");
-	trusted_mods.erase(std::remove_if(trusted_mods.begin(),
-			trusted_mods.end(), static_cast<int(*)(int)>(&std::isspace)),
-			trusted_mods.end());
-	std::vector<std::string> mod_list = str_split(trusted_mods, ',');
-	if (std::find(mod_list.begin(), mod_list.end(), mod_name) ==
-			mod_list.end()) {
+	if (!ScriptApiSecurity::checkWhitelisted(L, "secure.trusted_mods")) {
 		return 0;
 	}