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Mod security: Allow read-only access to all mod paths

This commit is contained in:
ShadowNinja 2016-12-05 19:59:15 +00:00 committed by paramat
parent 24edfb77af
commit 59f84ca0a0
8 changed files with 90 additions and 42 deletions
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60
src/script/cpp_api/s_security.cpp
View File

@ -336,8 +336,12 @@ bool ScriptApiSecurity::safeLoadFile(lua_State *L, const char *path)
}
bool ScriptApiSecurity::checkPath(lua_State *L, const char *path)
bool ScriptApiSecurity::checkPath(lua_State *L, const char *path,
bool write_required, bool *write_allowed)
{
if (write_allowed)
*write_allowed = false;
std::string str; // Transient
std::string norel_path = fs::RemoveRelativePathComponents(path);
@ -380,33 +384,54 @@ bool ScriptApiSecurity::checkPath(lua_State *L, const char *path)
// Builtin can access anything
if (mod_name == BUILTIN_MOD_NAME) {
if (write_allowed) *write_allowed = true;
return true;
}
// Allow paths in mod path
// Don't bother if write access isn't important, since it will be handled later
if (write_required || write_allowed != NULL) {
const ModSpec *mod = server->getModSpec(mod_name);
if (mod) {
str = fs::AbsolutePath(mod->path);
if (!str.empty() && fs::PathStartsWith(abs_path, str)) {
if (write_allowed) *write_allowed = true;
return true;
}
}
}
}
lua_pop(L, 1); // Pop mod name
// Allow read-only access to all mod directories
if (!write_required) {
const std::vector<ModSpec> mods = server->getMods();
for (size_t i = 0; i < mods.size(); ++i) {
str = fs::AbsolutePath(mods[i].path);
if (!str.empty() && fs::PathStartsWith(abs_path, str)) {
return true;
}
}
}
str = fs::AbsolutePath(server->getWorldPath());
if (str.empty()) return false;
// Don't allow access to world mods. We add to the absolute path
// of the world instead of getting the absolute paths directly
// because that won't work if they don't exist.
if (!str.empty()) {
// Don't allow access to other paths in the world mod/game path.
// These have to be blocked so you can't override a trusted mod
// by creating a mod with the same name in a world mod directory.
// We add to the absolute path of the world instead of getting
// the absolute paths directly because that won't work if they
// don't exist.
if (fs::PathStartsWith(abs_path, str + DIR_DELIM + "worldmods") ||
fs::PathStartsWith(abs_path, str + DIR_DELIM + "game")) {
return false;
}
// Allow all other paths in world path
if (fs::PathStartsWith(abs_path, str)) {
if (write_allowed) *write_allowed = true;
return true;
}
}
// Default to disallowing
return false;
@ -476,7 +501,7 @@ int ScriptApiSecurity::sl_g_loadfile(lua_State *L)
if (lua_isstring(L, 1)) {
path = lua_tostring(L, 1);
CHECK_SECURE_PATH(L, path);
CHECK_SECURE_PATH_INTERNAL(L, path, false, NULL);
}
if (!safeLoadFile(L, path)) {
@ -529,7 +554,16 @@ int ScriptApiSecurity::sl_io_open(lua_State *L)
luaL_checktype(L, 1, LUA_TSTRING);
const char *path = lua_tostring(L, 1);
CHECK_SECURE_PATH(L, path);
bool write_requested = false;
if (with_mode) {
luaL_checktype(L, 2, LUA_TSTRING);
const char *mode = lua_tostring(L, 2);
write_requested = strchr(mode, 'w') != NULL ||
strchr(mode, '+') != NULL ||
strchr(mode, 'a') != NULL;
}
CHECK_SECURE_PATH_INTERNAL(L, path, write_requested, NULL);
push_original(L, "io", "open");
lua_pushvalue(L, 1);
@ -546,7 +580,7 @@ int ScriptApiSecurity::sl_io_input(lua_State *L)
{
if (lua_isstring(L, 1)) {
const char *path = lua_tostring(L, 1);
CHECK_SECURE_PATH(L, path);
CHECK_SECURE_PATH_INTERNAL(L, path, false, NULL);
}
push_original(L, "io", "input");
@ -560,7 +594,7 @@ int ScriptApiSecurity::sl_io_output(lua_State *L)
{
if (lua_isstring(L, 1)) {
const char *path = lua_tostring(L, 1);
CHECK_SECURE_PATH(L, path);
CHECK_SECURE_PATH_INTERNAL(L, path, true, NULL);
}
push_original(L, "io", "output");
@ -574,7 +608,7 @@ int ScriptApiSecurity::sl_io_lines(lua_State *L)
{
if (lua_isstring(L, 1)) {
const char *path = lua_tostring(L, 1);
CHECK_SECURE_PATH(L, path);
CHECK_SECURE_PATH_INTERNAL(L, path, false, NULL);
}
int top_precall = lua_gettop(L);
@ -591,11 +625,11 @@ int ScriptApiSecurity::sl_os_rename(lua_State *L)
{
luaL_checktype(L, 1, LUA_TSTRING);
const char *path1 = lua_tostring(L, 1);
CHECK_SECURE_PATH(L, path1);
CHECK_SECURE_PATH_INTERNAL(L, path1, true, NULL);
luaL_checktype(L, 2, LUA_TSTRING);
const char *path2 = lua_tostring(L, 2);
CHECK_SECURE_PATH(L, path2);
CHECK_SECURE_PATH_INTERNAL(L, path2, true, NULL);
push_original(L, "os", "rename");
lua_pushvalue(L, 1);
@ -609,7 +643,7 @@ int ScriptApiSecurity::sl_os_remove(lua_State *L)
{
luaL_checktype(L, 1, LUA_TSTRING);
const char *path = lua_tostring(L, 1);
CHECK_SECURE_PATH(L, path);
CHECK_SECURE_PATH_INTERNAL(L, path, true, NULL);
push_original(L, "os", "remove");
lua_pushvalue(L, 1);

21
src/script/cpp_api/s_security.h
View File

@ -23,14 +23,18 @@ with this program; if not, write to the Free Software Foundation, Inc.,
#include "cpp_api/s_base.h"
#define CHECK_SECURE_PATH(L, path) \
if (!ScriptApiSecurity::checkPath(L, path)) { \
throw LuaError(std::string("Attempt to access external file ") + \
path + " with mod security on."); \
#define CHECK_SECURE_PATH_INTERNAL(L, path, write_required, ptr) \
if (!ScriptApiSecurity::checkPath(L, path, write_required, ptr)) { \
throw LuaError(std::string("Mod security: Blocked attempted ") + \
(write_required ? "write to " : "read from ") + path); \
}
#define CHECK_SECURE_PATH_OPTIONAL(L, path) \
#define CHECK_SECURE_PATH(L, path, write_required) \
if (ScriptApiSecurity::isSecure(L)) { \
CHECK_SECURE_PATH(L, path); \
CHECK_SECURE_PATH_INTERNAL(L, path, write_required, NULL); \
}
#define CHECK_SECURE_PATH_POSSIBLE_WRITE(L, path, ptr) \
if (ScriptApiSecurity::isSecure(L)) { \
CHECK_SECURE_PATH_INTERNAL(L, path, false, ptr); \
}
@ -43,8 +47,9 @@ public:
static bool isSecure(lua_State *L);
// Loads a file as Lua code safely (doesn't allow bytecode).
static bool safeLoadFile(lua_State *L, const char *path);
// Checks if mods are allowed to read and write to the path
static bool checkPath(lua_State *L, const char *path);
// 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);
private:
// Syntax: "sl_" <Library name or 'g' (global)> '_' <Function name>

4
src/script/lua_api/l_areastore.cpp
View File

@ -263,7 +263,7 @@ int LuaAreaStore::l_to_file(lua_State *L)
AreaStore *ast = o->as;
const char *filename = luaL_checkstring(L, 2);
CHECK_SECURE_PATH_OPTIONAL(L, filename);
CHECK_SECURE_PATH(L, filename, true);
std::ostringstream os(std::ios_base::binary);
ast->serialize(os);
@ -294,7 +294,7 @@ int LuaAreaStore::l_from_file(lua_State *L)
LuaAreaStore *o = checkobject(L, 1);
const char *filename = luaL_checkstring(L, 2);
CHECK_SECURE_PATH_OPTIONAL(L, filename);
CHECK_SECURE_PATH(L, filename, false);
std::ifstream is(filename, std::ios::binary);
return deserialization_helper(L, o->as, is);

2
src/script/lua_api/l_mapgen.cpp
View File

@ -1295,7 +1295,7 @@ int ModApiMapgen::l_create_schematic(lua_State *L)
INodeDefManager *ndef = getServer(L)->getNodeDefManager();
const char *filename = luaL_checkstring(L, 4);
CHECK_SECURE_PATH_OPTIONAL(L, filename);
CHECK_SECURE_PATH(L, filename, true);
Map *map = &(getEnv(L)->getMap());
Schematic schem;

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

@ -118,6 +118,11 @@ int LuaSettings::l_write(lua_State* L)
NO_MAP_LOCK_REQUIRED;
LuaSettings* o = checkobject(L, 1);
if (!o->m_write_allowed) {
throw LuaError("Settings: writing " + o->m_filename +
" not allowed with mod security on.");
}
bool success = o->m_settings->updateConfigFile(o->m_filename.c_str());
lua_pushboolean(L, success);
@ -142,8 +147,9 @@ int LuaSettings::l_to_table(lua_State* L)
return 1;
}
LuaSettings::LuaSettings(const char* filename)
LuaSettings::LuaSettings(const char* filename, bool write_allowed)
{
m_write_allowed = write_allowed;
m_filename = std::string(filename);
m_settings = new Settings();
@ -188,9 +194,10 @@ void LuaSettings::Register(lua_State* L)
int LuaSettings::create_object(lua_State* L)
{
NO_MAP_LOCK_REQUIRED;
bool write_allowed;
const char* filename = luaL_checkstring(L, 1);
CHECK_SECURE_PATH_OPTIONAL(L, filename);
LuaSettings* o = new LuaSettings(filename);
CHECK_SECURE_PATH_POSSIBLE_WRITE(L, filename, &write_allowed);
LuaSettings* o = new LuaSettings(filename, write_allowed);
*(void **)(lua_newuserdata(L, sizeof(void *))) = o;
luaL_getmetatable(L, className);
lua_setmetatable(L, -2);

3
src/script/lua_api/l_settings.h
View File

@ -53,11 +53,12 @@ private:
// to_table(self) -> {[key1]=value1,...}
static int l_to_table(lua_State* L);
bool m_write_allowed;
Settings* m_settings;
std::string m_filename;
public:
LuaSettings(const char* filename);
LuaSettings(const char* filename, bool write_allowed);
~LuaSettings();
// LuaSettings(filename)

4
src/script/lua_api/l_util.cpp
View File

@ -388,7 +388,7 @@ int ModApiUtil::l_mkdir(lua_State *L)
{
NO_MAP_LOCK_REQUIRED;
const char *path = luaL_checkstring(L, 1);
CHECK_SECURE_PATH_OPTIONAL(L, path);
CHECK_SECURE_PATH(L, path, true);
lua_pushboolean(L, fs::CreateAllDirs(path));
return 1;
}
@ -400,7 +400,7 @@ int ModApiUtil::l_get_dir_list(lua_State *L)
const char *path = luaL_checkstring(L, 1);
short is_dir = lua_isboolean(L, 2) ? lua_toboolean(L, 2) : -1;
CHECK_SECURE_PATH_OPTIONAL(L, path);
CHECK_SECURE_PATH(L, path, false);
std::vector<fs::DirListNode> list = fs::GetDirListing(path);

1
src/server.h
View File

@ -298,6 +298,7 @@ public:
IWritableNodeDefManager* getWritableNodeDefManager();
IWritableCraftDefManager* getWritableCraftDefManager();
const std::vector<ModSpec> &getMods() const { return m_mods; }
const ModSpec* getModSpec(const std::string &modname) const;
void getModNames(std::vector<std::string> &modlist);
std::string getBuiltinLuaPath();