File

plugins/mod_s2s_bidi.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 10458:602dd1e2f399
child 12330:38b5b05407be
line wrap: on
line source

-- Prosody IM
-- Copyright (C) 2019 Kim Alvefur
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

local st = require "util.stanza";

local xmlns_bidi_feature = "urn:xmpp:features:bidi"
local xmlns_bidi = "urn:xmpp:bidi";

local require_encryption = module:get_option_boolean("s2s_require_encryption", false);

module:hook("s2s-stream-features", function(event)
	local origin, features = event.origin, event.features;
	if origin.type == "s2sin_unauthed" and (not require_encryption or origin.secure) then
		features:tag("bidi", { xmlns = xmlns_bidi_feature }):up();
	end
end);

module:hook_tag("http://etherx.jabber.org/streams", "features", function (session, stanza)
	if session.type == "s2sout_unauthed" and (not require_encryption or session.secure) then
		local bidi = stanza:get_child("bidi", xmlns_bidi_feature);
		if bidi then
			session.incoming = true;
			session.log("debug", "Requesting bidirectional stream");
			session.sends2s(st.stanza("bidi", { xmlns = xmlns_bidi }));
		end
	end
end, 200);

module:hook_tag("urn:xmpp:bidi", "bidi", function(session)
	if session.type == "s2sin_unauthed" and (not require_encryption or session.secure) then
		session.log("debug", "Requested bidirectional stream");
		session.outgoing = true;
		return true;
	end
end);