Add csm_strict
This commit is contained in:
luk3yx
parent
f1cc6bc494
commit
9363bbbc78
|
|
@ -0,0 +1,7 @@
|
|||
# Minetest server-sent CSM proof-of-concept
|
||||
|
||||
This CSM asks permission before allowing SSCSMs to run. The allow/deny formspec
|
||||
name is randomly generated to prevent servers from creating fake allow/deny
|
||||
formspecs.
|
||||
|
||||
CSM installation guide: https://forum.minetest.net/viewtopic.php?f=53&t=17830
|
||||
|
|
@ -0,0 +1,413 @@
|
|||
--
|
||||
-- SSCSM: Server-Sent Client-Side Mods proof-of-concept: "Strict" version
|
||||
--
|
||||
-- © 2019 by luk3yx
|
||||
--
|
||||
|
||||
-- For debugging, this can be a global variable.
|
||||
local sscsm = {}
|
||||
|
||||
-- Add a random number onto the current time in case servers try and predict
|
||||
-- the random seed
|
||||
math.randomseed(os.time() + math.random(2, 1200))
|
||||
|
||||
-- Load the Env class
|
||||
-- Mostly copied from https://stackoverflow.com/a/26367080
|
||||
-- Don't copy metatables
|
||||
local function copy(obj, s)
|
||||
if s and s[obj] ~= nil then return s[obj] end
|
||||
if type(obj) ~= 'table' then return obj end
|
||||
s = s or {}
|
||||
local res = {}
|
||||
s[obj] = res
|
||||
for k, v in pairs(obj) do res[copy(k, s)] = copy(v, s) end
|
||||
return res
|
||||
end
|
||||
|
||||
-- Safe functions
|
||||
local Env = {}
|
||||
local safe_funcs = {}
|
||||
|
||||
-- No getmetatable()
|
||||
if rawget(_G, 'getmetatable') then
|
||||
safe_funcs[getmetatable] = function() end
|
||||
end
|
||||
|
||||
-- Get the current value of string.rep in case other CSMs decide to break
|
||||
do
|
||||
safe_funcs[math.randomseed] = function() end
|
||||
|
||||
local rep = string.rep
|
||||
safe_funcs[string.rep] = function(str, n)
|
||||
if #str * n > 1048576 then
|
||||
error('string.rep: string length overflow', 2)
|
||||
end
|
||||
return rep(str, n)
|
||||
end
|
||||
|
||||
local show_formspec = minetest.show_formspec
|
||||
safe_funcs[show_formspec] = function(formname, ...)
|
||||
if type(formname) == 'string' and formname:sub(1, 6) ~= 'sscsm:' then
|
||||
return show_formspec(formname, ...)
|
||||
end
|
||||
end
|
||||
|
||||
local after = minetest.after
|
||||
safe_funcs[after] = function(n, ...)
|
||||
if type(n) == 'number' then return after(n, pcall, ...) end
|
||||
end
|
||||
|
||||
local on_fs_input = minetest.register_on_formspec_input
|
||||
safe_funcs[on_fs_input] = function(func)
|
||||
on_fs_input(function(formname, fields)
|
||||
if formname:sub(1, 6) ~= 'sscsm:' then
|
||||
pcall(func, formname, copy(fields))
|
||||
end
|
||||
end)
|
||||
end
|
||||
|
||||
local wrap = function(n)
|
||||
local orig = minetest[n] or minetest[n .. 's']
|
||||
if type(orig) == 'function' then
|
||||
return function(func)
|
||||
orig(function(...)
|
||||
local r = {pcall(func, ...)}
|
||||
if r[1] then
|
||||
table.remove(r, 1)
|
||||
return (table.unpack or unpack)(r)
|
||||
else
|
||||
minetest.log('error', '[SSCSM] ' .. tostring(r[2]))
|
||||
end
|
||||
end)
|
||||
end
|
||||
end
|
||||
end
|
||||
|
||||
for _, k in ipairs({'register_globalstep', 'register_on_death',
|
||||
'register_on_hp_modification', 'register_on_damage_taken',
|
||||
'register_on_dignode', 'register_on_punchnode',
|
||||
'register_on_placenode', 'register_on_item_use',
|
||||
'register_on_modchannel_message', 'register_on_modchannel_signal',
|
||||
'register_on_inventory_open', 'register_on_sending_chat_message',
|
||||
'register_on_receiving_chat_message'}) do
|
||||
safe_funcs[minetest[k]] = wrap(k)
|
||||
end
|
||||
end
|
||||
|
||||
-- Environment
|
||||
function Env.new_empty()
|
||||
local self = {_raw = {}, _seen = copy(safe_funcs)}
|
||||
self._raw['_G'] = self._raw
|
||||
return setmetatable(self, {__index = Env}) or self
|
||||
end
|
||||
function Env:get(k) return self._raw[self._seen[k] or k] end
|
||||
function Env:set(k, v) self._raw[copy(k, self._seen)] = copy(v, self._seen) end
|
||||
function Env:set_copy(k, v)
|
||||
self:set(k, v)
|
||||
self._seen[k] = nil
|
||||
self._seen[v] = nil
|
||||
end
|
||||
function Env:add_globals(...)
|
||||
for i = 1, select('#', ...) do
|
||||
local var = select(i, ...)
|
||||
self:set(var, _G[var])
|
||||
end
|
||||
end
|
||||
function Env:update(data) for k, v in pairs(data) do self:set(k, v) end end
|
||||
function Env:del(k)
|
||||
if self._seen[k] then
|
||||
self._raw[self._seen[k]] = nil
|
||||
self._seen[k] = nil
|
||||
end
|
||||
self._raw[k] = nil
|
||||
end
|
||||
|
||||
function Env:copy()
|
||||
local new = {_seen = copy(safe_funcs)}
|
||||
new._raw = copy(self._raw, new._seen)
|
||||
return setmetatable(new, {__index = Env}) or new
|
||||
end
|
||||
|
||||
-- Load code into a callable function.
|
||||
function Env:loadstring(code)
|
||||
if code:byte(1) == 27 then return nil, 'Invalid code!' end
|
||||
local f, msg = loadstring(code)
|
||||
if not f then return nil, msg end
|
||||
setfenv(f, self._raw)
|
||||
return function(...)
|
||||
local good, msg = pcall(f, ...)
|
||||
if good then
|
||||
return msg
|
||||
else
|
||||
minetest.log('error', '[SSCSM] ' .. tostring(msg))
|
||||
end
|
||||
end
|
||||
end
|
||||
|
||||
function Env:exec(code)
|
||||
local f, msg = self:loadstring(code)
|
||||
if not f then
|
||||
minetest.log('error', '[SSCSM] Syntax error: ' .. tostring(msg))
|
||||
return false
|
||||
end
|
||||
f()
|
||||
return true
|
||||
end
|
||||
|
||||
-- Create the "base" environment
|
||||
local base_env = Env:new_empty()
|
||||
function Env.new() return base_env:copy() end
|
||||
|
||||
-- Clone everything
|
||||
base_env:add_globals('dump', 'dump2', 'error', 'ipairs', 'math', 'next',
|
||||
'pairs', 'pcall', 'select', 'setmetatable', 'string', 'table', 'tonumber',
|
||||
'tostring', 'type', 'vector', 'xpcall', '_VERSION')
|
||||
|
||||
base_env:set_copy('os', {clock = os.clock, difftime = os.difftime,
|
||||
time = os.time})
|
||||
|
||||
-- Create a slightly locked down "minetest" table
|
||||
do
|
||||
local t = {}
|
||||
for _, k in ipairs({"add_particle", "add_particlespawner", "after",
|
||||
"camera", "clear_out_chat_queue", "colorize", "compress", "debug",
|
||||
"decode_base64", "decompress", "delete_particlespawner",
|
||||
"deserialize", "disconnect", "display_chat_message",
|
||||
"encode_base64", "explode_scrollbar_event", "explode_table_event",
|
||||
"explode_textlist_event", "find_node_near", "formspec_escape",
|
||||
"get_background_escape_sequence", "get_color_escape_sequence",
|
||||
"get_day_count", "get_item_def", "get_language", "get_meta",
|
||||
"get_node_def", "get_node_level", "get_node_max_level",
|
||||
"get_node_or_nil", "get_player_names", "get_privilege_list",
|
||||
"get_server_info", "get_timeofday", "get_translator",
|
||||
"get_us_time", "get_version", "get_wielded_item", "gettext",
|
||||
"is_nan", "is_yes", "localplayer", "log",
|
||||
"mod_channel_join", "parse_json", "pointed_thing_to_face_pos",
|
||||
"pos_to_string", "privs_to_string", "register_globalstep",
|
||||
"register_on_damage_taken", "register_on_death",
|
||||
"register_on_dignode", "register_on_formspec_input",
|
||||
"register_on_hp_modification", "register_on_inventory_open",
|
||||
"register_on_item_use", "register_on_modchannel_message",
|
||||
"register_on_modchannel_signal", "register_on_placenode",
|
||||
"register_on_punchnode", "register_on_receiving_chat_message",
|
||||
"register_on_sending_chat_message", "rgba",
|
||||
"run_server_chatcommand", "send_chat_message", "send_respawn",
|
||||
"serialize", "sha1", "show_formspec", "sound_play", "sound_stop",
|
||||
"string_to_area", "string_to_pos", "string_to_privs",
|
||||
"strip_background_colors", "strip_colors",
|
||||
"strip_foreground_colors", "translate", "ui", "wrap_text",
|
||||
"write_json"}) do
|
||||
local func = minetest[k]
|
||||
t[k] = safe_funcs[func] or func
|
||||
end
|
||||
|
||||
base_env:set_copy('minetest', t)
|
||||
end
|
||||
|
||||
-- Add table.unpack
|
||||
if not table.unpack then
|
||||
base_env._raw.table.unpack = unpack
|
||||
end
|
||||
|
||||
-- Make sure copy() worked correctly
|
||||
assert(base_env._raw.minetest.register_on_sending_chat_message ~=
|
||||
minetest.register_on_sending_chat_message, 'Error in copy()!')
|
||||
|
||||
-- SSCSM functions
|
||||
-- When calling these from an SSCSM, make sure they exist first.
|
||||
local mod_channel = minetest.mod_channel_join('sscsm:exec_pipe')
|
||||
local loaded_sscsms = {}
|
||||
base_env:set('join_mod_channel', function()
|
||||
if not mod_channel then
|
||||
mod_channel = minetest.mod_channel_join('sscsm:exec_pipe')
|
||||
end
|
||||
end)
|
||||
|
||||
base_env:set('leave_mod_channel', function()
|
||||
if mod_channel then
|
||||
mod_channel:leave()
|
||||
mod_channel = false
|
||||
end
|
||||
end)
|
||||
|
||||
-- Allow other CSMs to access the new Environment type
|
||||
sscsm.Env = Env
|
||||
|
||||
-- exec() code sent by the server.
|
||||
local sscsm_queue = {}
|
||||
|
||||
minetest.register_on_modchannel_message(function(channel_name, sender, message)
|
||||
if channel_name ~= 'sscsm:exec_pipe' or (sender and sender ~= '')
|
||||
or #sscsm_queue > 512 then
|
||||
return
|
||||
end
|
||||
|
||||
-- The first character is currently a version code, currently 0.
|
||||
-- Do not change unless absolutely necessary.
|
||||
local version = message:sub(1, 1)
|
||||
local name, code
|
||||
if version == '0' then
|
||||
local s, e = message:find('\n')
|
||||
if not s or not e then return end
|
||||
local target = message:sub(2, s - 1)
|
||||
if target ~= minetest.localplayer:get_name() then return end
|
||||
message = message:sub(e + 1)
|
||||
local s, e = message:find('\n')
|
||||
if not s or not e then return end
|
||||
name = message:sub(1, s - 1)
|
||||
code = message:sub(e + 1)
|
||||
else
|
||||
return
|
||||
end
|
||||
|
||||
-- Don't load the same SSCSM twice
|
||||
if not loaded_sscsms[name] then
|
||||
loaded_sscsms[name] = true
|
||||
if sscsm_queue then
|
||||
if sscsm.allowed == nil then
|
||||
local info = minetest.get_server_info()
|
||||
local addr = tostring(info.address)
|
||||
if addr == '' then
|
||||
addr = 'singleplayer'
|
||||
else
|
||||
addr = addr .. ':' .. tostring(info.port)
|
||||
end
|
||||
minetest.display_chat_message(minetest.colorize('#eeeeee',
|
||||
'[SSCSM] This server (' .. minetest.formspec_escape(addr) ..
|
||||
') wants to run sandboxed code on your client. ' ..
|
||||
'Run .sscsm to allow or deny this.'))
|
||||
sscsm_stage = 1
|
||||
sscsm.allowed = false
|
||||
end
|
||||
table.insert(sscsm_queue, {name=name, code=code})
|
||||
elseif sscsm.allowed then
|
||||
-- Create the environment
|
||||
minetest.log('action', '[SSCSM] Loading ' .. name)
|
||||
if not sscsm.env then sscsm.env = Env:new() end
|
||||
sscsm.env:exec(code)
|
||||
end
|
||||
end
|
||||
end)
|
||||
|
||||
-- Send "0"
|
||||
local function request_csms(c)
|
||||
c = c or 10
|
||||
if c <= 0 then return end
|
||||
if minetest.localplayer and mod_channel:is_writeable() then
|
||||
mod_channel:send_all('0')
|
||||
else
|
||||
minetest.after(0.1, request_csms, c - 1)
|
||||
end
|
||||
end
|
||||
minetest.after(0, request_csms)
|
||||
|
||||
-- "Securely" display a formspec
|
||||
local function random_identifier()
|
||||
return tostring(math.random() + math.random(0, 1000000000))
|
||||
end
|
||||
|
||||
local secure_show_formspec, current_formname
|
||||
do
|
||||
local _show_formspec = minetest.show_formspec
|
||||
function secure_show_formspec(spec)
|
||||
-- Regenerate the formname every time.
|
||||
current_formname = 'sscsm:' .. random_identifier()
|
||||
|
||||
-- Display the formspec
|
||||
minetest.show_formspec(current_formname, spec)
|
||||
end
|
||||
end
|
||||
|
||||
local allow_id, deny_id
|
||||
local function show_default_formspec()
|
||||
local allow_text, deny_text, allowed
|
||||
if sscsm.allowed then
|
||||
deny_text = 'Exit to menu'
|
||||
allow_text = 'Close dialog'
|
||||
allowed = minetest.colorize('orange', 'running')
|
||||
elseif sscsm_queue then
|
||||
deny_text = 'Deny'
|
||||
allow_text = 'Allow'
|
||||
allowed = 'inactive'
|
||||
else
|
||||
allowed = minetest.colorize('lightgreen', 'disabled')
|
||||
end
|
||||
|
||||
local formspec = 'size[8,4]no_prepend[]' ..
|
||||
'image_button[0,0;8,1;;ignore;SSCSM;true;false;]' ..
|
||||
'label[0,1;SSCSMs are currently ' ..
|
||||
minetest.formspec_escape(allowed) .. '.]'
|
||||
|
||||
if allowed == 'inactive' then
|
||||
formspec = formspec ..
|
||||
'label[0,2;Do you want to allow this server to ' ..
|
||||
'execute (sandboxed) code locally?]'
|
||||
else
|
||||
formspec = formspec ..
|
||||
'label[0,2;You cannot change this without reconnecting.]'
|
||||
end
|
||||
|
||||
if allow_text and deny_text then
|
||||
formspec = formspec .. 'button_exit[0,3;4,1;deny;' ..
|
||||
minetest.formspec_escape(deny_text) .. ']' ..
|
||||
'button_exit[4,3;4,1;allow;' ..
|
||||
minetest.formspec_escape(allow_text) .. ']'
|
||||
else
|
||||
formspec = formspec .. 'button_exit[0,3;8,1;deny;Close dialog]'
|
||||
end
|
||||
|
||||
secure_show_formspec(formspec)
|
||||
end
|
||||
|
||||
-- Handle formspec input
|
||||
minetest.register_on_formspec_input(function(formname, fields)
|
||||
-- Sanity check
|
||||
if not current_formname or formname ~= current_formname then return end
|
||||
|
||||
-- Minetest will leak the formname to the currently untrusted server after
|
||||
-- this, so invalidate it now.
|
||||
current_formname = false
|
||||
|
||||
-- Check for options
|
||||
if fields.deny then
|
||||
if sscsm.allowed then
|
||||
minetest.disconnect()
|
||||
end
|
||||
if sscsm_queue then
|
||||
sscsm_queue = false
|
||||
minetest.display_chat_message('[SSCSM] SSCSMs have been denied.')
|
||||
end
|
||||
elseif fields.allow then
|
||||
if sscsm.allowed then return true end
|
||||
|
||||
minetest.display_chat_message('[SSCSM] SSCSMs have been allowed.')
|
||||
sscsm.allowed = true
|
||||
if sscsm_queue then
|
||||
if not sscsm.env then sscsm.env = Env:new() end
|
||||
for _, def in ipairs(sscsm_queue) do
|
||||
minetest.log('action', '[SSCSM] Loading ' .. def.name)
|
||||
sscsm.env:exec(def.code)
|
||||
end
|
||||
end
|
||||
sscsm_queue = false
|
||||
elseif fields.quit then
|
||||
minetest.display_chat_message(minetest.colorize('#eeeeee',
|
||||
'[SSCSM] No action specified.'))
|
||||
else
|
||||
show_default_formspec()
|
||||
end
|
||||
|
||||
return true
|
||||
end)
|
||||
|
||||
-- Add .sscsm
|
||||
minetest.register_chatcommand('sscsm', {
|
||||
descrption = 'Displays SSCSM options for this server.',
|
||||
func = function(param)
|
||||
if sscsm.allowed == nil then
|
||||
return false, 'This server has not attempted to load any SSCSMs.'
|
||||
else
|
||||
show_default_formspec()
|
||||
end
|
||||
end
|
||||
})
|
||||
Loading…
Reference in New Issue