File

plugins/mod_csi.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 10429:0b04d25c4ffb
child 12977:74b9e05af71e
line wrap: on
line source

local st = require "util.stanza";
local xmlns_csi = "urn:xmpp:csi:0";
local csi_feature = st.stanza("csi", { xmlns = xmlns_csi });

local csi_handler_available = nil;
module:hook("stream-features", function (event)
	if event.origin.username and csi_handler_available then
		event.features:add_child(csi_feature);
	end
end);

function refire_event(name)
	return function (event)
		if event.origin.username then
			event.origin.state = event.stanza.name;
			module:fire_event(name, event);
			return true;
		end
	end;
end

module:hook("stanza/"..xmlns_csi..":active", refire_event("csi-client-active"));
module:hook("stanza/"..xmlns_csi..":inactive", refire_event("csi-client-inactive"));

function module.load()
	if prosody.hosts[module.host].events._handlers["csi-client-active"] then
		csi_handler_available = true;
		module:set_status("core", "CSI handler module loaded");
	else
		csi_handler_available = false;
		module:set_status("warn", "No CSI handler module loaded");
	end
end
module:hook("module-loaded", module.load);
module:hook("module-unloaded", module.load);