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util/dependencies.lua @ 12181:783056b4e448 0.11 0.11.12
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 | 11140:e17b98feb0b7 |
child | 11141:a5acd6354845 |
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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. -- local function softreq(...) local ok, lib = pcall(require, ...); if ok then return lib; else return nil, lib; end end -- Required to be able to find packages installed with luarocks if not softreq "luarocks.loader" then -- LuaRocks 2.x softreq "luarocks.require"; -- LuaRocks <1.x end local function missingdep(name, sources, msg) print(""); print("**************************"); print("Prosody was unable to find "..tostring(name)); print("This package can be obtained in the following ways:"); print(""); local longest_platform = 0; for platform in pairs(sources) do longest_platform = math.max(longest_platform, #platform); end for platform, source in pairs(sources) do print("", platform..":"..(" "):rep(4+longest_platform-#platform)..source); end print(""); print(msg or (name.." is required for Prosody to run, so we will now exit.")); print("More help can be found on our website, at https://prosody.im/doc/depends"); print("**************************"); print(""); end local function check_dependencies() if _VERSION < "Lua 5.1" then print "***********************************" print("Unsupported Lua version: ".._VERSION); print("At least Lua 5.1 is required."); print "***********************************" return false; end local fatal; local lxp = softreq "lxp" if not lxp then missingdep("luaexpat", { ["Debian/Ubuntu"] = "sudo apt-get install lua-expat"; ["luarocks"] = "luarocks install luaexpat"; ["Source"] = "http://matthewwild.co.uk/projects/luaexpat/"; }); fatal = true; end local socket = softreq "socket" if not socket then missingdep("luasocket", { ["Debian/Ubuntu"] = "sudo apt-get install lua-socket"; ["luarocks"] = "luarocks install luasocket"; ["Source"] = "http://www.tecgraf.puc-rio.br/~diego/professional/luasocket/"; }); fatal = true; elseif not socket.tcp4 then -- COMPAT LuaSocket before being IP-version agnostic socket.tcp4 = socket.tcp; socket.udp4 = socket.udp; end local lfs, err = softreq "lfs" if not lfs then missingdep("luafilesystem", { ["luarocks"] = "luarocks install luafilesystem"; ["Debian/Ubuntu"] = "sudo apt-get install lua-filesystem"; ["Source"] = "http://www.keplerproject.org/luafilesystem/"; }); fatal = true; end local ssl = softreq "ssl" if not ssl then missingdep("LuaSec", { ["Debian/Ubuntu"] = "sudo apt-get install lua-sec"; ["luarocks"] = "luarocks install luasec"; ["Source"] = "https://github.com/brunoos/luasec"; }, "SSL/TLS support will not be available"); end local bit = softreq"bit" or softreq"bit32"; if not bit then missingdep("lua-bitops", { ["Debian/Ubuntu"] = "sudo apt-get install lua-bitop"; ["luarocks"] = "luarocks install luabitop"; ["Source"] = "http://bitop.luajit.org/"; }, "WebSocket support will not be available"); end local encodings, err = softreq "util.encodings" if not encodings then if err:match("module '[^']*' not found") then missingdep("util.encodings", { ["Windows"] = "Make sure you have encodings.dll from the Prosody distribution in util/"; ["GNU/Linux"] = "Run './configure' and 'make' in the Prosody source directory to build util/encodings.so"; }); else print "***********************************" print("util/encodings couldn't be loaded. Check that you have a recent version of libidn"); print "" print("The full error was:"); print(err) print "***********************************" end fatal = true; end local hashes, err = softreq "util.hashes" if not hashes then if err:match("module '[^']*' not found") then missingdep("util.hashes", { ["Windows"] = "Make sure you have hashes.dll from the Prosody distribution in util/"; ["GNU/Linux"] = "Run './configure' and 'make' in the Prosody source directory to build util/hashes.so"; }); else print "***********************************" print("util/hashes couldn't be loaded. Check that you have a recent version of OpenSSL (libcrypto in particular)"); print "" print("The full error was:"); print(err) print "***********************************" end fatal = true; end return not fatal; end local function log_warnings() if _VERSION > "Lua 5.2" then prosody.log("warn", "Support for %s is experimental, please report any issues", _VERSION); end local ssl = softreq"ssl"; if ssl then local major, minor, veryminor, patched = ssl._VERSION:match("(%d+)%.(%d+)%.?(%d*)(M?)"); if not major or ((tonumber(major) == 0 and (tonumber(minor) or 0) <= 3 and (tonumber(veryminor) or 0) <= 2) and patched ~= "M") then prosody.log("error", "This version of LuaSec contains a known bug that causes disconnects, see https://prosody.im/doc/depends"); end end local lxp = softreq"lxp"; if lxp then if not pcall(lxp.new, { StartDoctypeDecl = false }) then prosody.log("error", "The version of LuaExpat on your system leaves Prosody " .."vulnerable to denial-of-service attacks. You should upgrade to " .."LuaExpat 1.3.0 or higher as soon as possible. See " .."https://prosody.im/doc/depends#luaexpat for more information."); end if not lxp.new({}).getcurrentbytecount then prosody.log("error", "The version of LuaExpat on your system does not support " .."stanza size limits, which may leave servers on untrusted " .."networks (e.g. the internet) vulnerable to denial-of-service " .."attacks. You should upgrade to LuaExpat 1.3.0 or higher as " .."soon as possible. See " .."https://prosody.im/doc/depends#luaexpat for more information."); end end end return { softreq = softreq; missingdep = missingdep; check_dependencies = check_dependencies; log_warnings = log_warnings; };