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plugins/mod_admin_telnet.lua @ 12180:53e0ae770917
util.xml: Do not allow doctypes, comments or processing instructions
Yes. This is as bad as it sounds. CVE pending.
In Prosody itself, this only affects mod_websocket, which uses util.xml
to parse the <open/> frame, thus allowing unauthenticated remote DoS
using Billion Laughs. However, third-party modules using util.xml may
also be affected by this.
This commit installs handlers which disallow the use of doctype
declarations and processing instructions without any escape hatch. It,
by default, also introduces such a handler for comments, however, there
is a way to enable comments nontheless.
This is because util.xml is used to parse human-facing data, where
comments are generally a desirable feature, and also because comments
are generally harmless.
author | Jonas Schäfer <jonas@wielicki.name> |
---|---|
date | Mon, 10 Jan 2022 18:23:54 +0100 |
parent | 10859:8de0057b4279 |
child | 12977:74b9e05af71e |
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-- Prosody IM -- Copyright (C) 2008-2010 Matthew Wild -- Copyright (C) 2008-2010 Waqas Hussain -- -- This project is MIT/X11 licensed. Please see the -- COPYING file in the source package for more information. -- -- luacheck: ignore 212/self module:set_global(); module:depends("admin_shell"); local console_listener = { default_port = 5582; default_mode = "*a"; interface = "127.0.0.1" }; local async = require "util.async"; local st = require "util.stanza"; local def_env = module:shared("admin_shell/env"); local default_env_mt = { __index = def_env }; local function printbanner(session) local option = module:get_option_string("console_banner", "full"); if option == "full" or option == "graphic" then session.print [[ ____ \ / _ | _ \ _ __ ___ ___ _-_ __| |_ _ | |_) | '__/ _ \/ __|/ _ \ / _` | | | | | __/| | | (_) \__ \ |_| | (_| | |_| | |_| |_| \___/|___/\___/ \__,_|\__, | A study in simplicity |___/ ]] end if option == "short" or option == "full" then session.print("Welcome to the Prosody administration console. For a list of commands, type: help"); session.print("You may find more help on using this console in our online documentation at "); session.print("https://prosody.im/doc/console\n"); end if option ~= "short" and option ~= "full" and option ~= "graphic" then session.print(option); end end console = {}; local runner_callbacks = {}; function runner_callbacks:ready() self.data.conn:resume(); end function runner_callbacks:waiting() self.data.conn:pause(); end function runner_callbacks:error(err) module:log("error", "Traceback[telnet]: %s", err); self.data.print("Fatal error while running command, it did not complete"); self.data.print("Error: "..tostring(err)); end function console:new_session(conn) local w = function(s) conn:write(s:gsub("\n", "\r\n")); end; local session = { conn = conn; send = function (t) if st.is_stanza(t) and (t.name == "repl-result" or t.name == "repl-output") then t = "| "..t:get_text().."\n"; end w(tostring(t)); end; print = function (...) local t = {}; for i=1,select("#", ...) do t[i] = tostring(select(i, ...)); end w("| "..table.concat(t, "\t").."\n"); end; serialize = tostring; disconnect = function () conn:close(); end; }; session.env = setmetatable({}, default_env_mt); session.thread = async.runner(function (line) console:process_line(session, line); session.send(string.char(0)); end, runner_callbacks, session); -- Load up environment with helper objects for name, t in pairs(def_env) do if type(t) == "table" then session.env[name] = setmetatable({ session = session }, { __index = t }); end end session.env.output:configure(); return session; end function console:process_line(session, line) line = line:gsub("\r?\n$", ""); if line == "bye" or line == "quit" or line == "exit" or line:byte() == 4 then session.print("See you!"); session:disconnect(); return; end return module:fire_event("admin/repl-input", { origin = session, stanza = st.stanza("repl-input"):text(line) }); end local sessions = {}; function module.save() return { sessions = sessions } end function module.restore(data) if data.sessions then for conn in pairs(data.sessions) do conn:setlistener(console_listener); local session = console:new_session(conn); sessions[conn] = session; end end end function console_listener.onconnect(conn) -- Handle new connection local session = console:new_session(conn); sessions[conn] = session; printbanner(session); session.send(string.char(0)); end function console_listener.onincoming(conn, data) local session = sessions[conn]; local partial = session.partial_data; if partial then data = partial..data; end for line in data:gmatch("[^\n]*[\n\004]") do if session.closed then return end session.thread:run(line); end session.partial_data = data:match("[^\n]+$"); end function console_listener.onreadtimeout(conn) local session = sessions[conn]; if session then session.send("\0"); return true; end end function console_listener.ondisconnect(conn, err) -- luacheck: ignore 212/err local session = sessions[conn]; if session then session.disconnect(); sessions[conn] = nil; end end function console_listener.ondetach(conn) sessions[conn] = nil; end module:provides("net", { name = "console"; listener = console_listener; default_port = 5582; private = true; });