File

plugins/muc/subject.lib.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 11128:c3eefb517b7b
child 11141:a5acd6354845
line wrap: on
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-- Prosody IM
-- Copyright (C) 2008-2010 Matthew Wild
-- Copyright (C) 2008-2010 Waqas Hussain
-- Copyright (C) 2014 Daurnimator
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

local st = require "util.stanza";
local dt = require "util.datetime";

local muc_util = module:require "muc/util";
local valid_roles = muc_util.valid_roles;

local function create_subject_message(from, subject)
	return st.message({from = from; type = "groupchat"})
		:tag("subject"):text(subject or ""):up();
end

local function get_changesubject(room)
	return room._data.changesubject;
end

local function set_changesubject(room, changesubject)
	changesubject = changesubject and true or nil;
	if get_changesubject(room) == changesubject then return false; end
	room._data.changesubject = changesubject;
	return true;
end

module:hook("muc-disco#info", function (event)
	table.insert(event.form, {
		name = "muc#roomconfig_changesubject";
		type = "boolean";
	});
	event.formdata["muc#roomconfig_changesubject"] = get_changesubject(event.room);
end);

module:hook("muc-config-form", function(event)
	table.insert(event.form, {
		name = "muc#roomconfig_changesubject";
		type = "boolean";
		label = "Allow anyone to set the room's subject";
		desc = "Choose whether anyone, or only moderators, may set the room's subject";
		value = get_changesubject(event.room);
	});
end, 80-1);

module:hook("muc-config-submitted/muc#roomconfig_changesubject", function(event)
	if set_changesubject(event.room, event.value) then
		event.status_codes["104"] = true;
	end
end);

local function get_subject(room)
	-- a <message/> stanza from the room JID (or from the occupant JID of the entity that set the subject)
	return room._data.subject_from or room.jid, room._data.subject;
end

local function send_subject(room, to, time)
	local msg = create_subject_message(get_subject(room));
	msg.attr.to = to;
	if time then
		msg:tag("delay", {
			xmlns = "urn:xmpp:delay",
			from = room.jid,
			stamp = dt.datetime(time);
		}):up();
	end
	room:route_stanza(msg);
end

local function set_subject(room, from, subject)
	if subject == "" then subject = nil; end
	local old_from, old_subject = get_subject(room);
	if old_subject == subject and old_from == from then return false; end
	room._data.subject_from = from;
	room._data.subject = subject;
	room._data.subject_time = os.time();
	local msg = create_subject_message(from, subject);
	room:broadcast_message(msg);
	return true;
end

-- Send subject to joining user
module:hook("muc-occupant-session-new", function(event)
	send_subject(event.room, event.stanza.attr.from, event.room._data.subject_time);
end, 20);

-- Prosody has made the decision that messages with <subject/> are exclusively subject changes
-- e.g. body will be ignored; even if the subject change was not allowed
module:hook("muc-occupant-groupchat", function(event)
	local stanza = event.stanza;
	local subject = stanza:get_child("subject");
	if subject then
		local room = event.room;
		local occupant = event.occupant;
		-- Role check for subject changes
		local role_rank = valid_roles[occupant and occupant.role or "none"];
		if role_rank >= valid_roles.moderator or
			( role_rank >= valid_roles.participant and get_changesubject(room) ) then -- and participant
			set_subject(room, occupant.nick, subject:get_text());
			room:save();
			return true;
		else
			event.origin.send(st.error_reply(stanza, "auth", "forbidden", "You are not allowed to change the subject"));
			return true;
		end
	end
end, 20);

return {
	get_changesubject = get_changesubject;
	set_changesubject = set_changesubject;
	get = get_subject;
	set = set_subject;
	send = send_subject;
};