File

util/session.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 10110:3fa3872588a8
child 12640:999b1c59af6f
line wrap: on
line source

local initialize_filters = require "util.filters".initialize;
local logger = require "util.logger";

local function new_session(typ)
	local session = {
		type = typ .. "_unauthed";
		base_type = typ;
	};
	return session;
end

local function set_id(session)
	local id = session.base_type .. tostring(session):match("%x+$"):lower();
	session.id = id;
	return session;
end

local function set_logger(session)
	local log = logger.init(session.id);
	session.log = log;
	return session;
end

local function set_conn(session, conn)
	session.conn = conn;
	session.ip = conn:ip();
	return session;
end

local function set_send(session)
	local conn = session.conn;
	if not conn then
		function session.send(data)
			session.log("debug", "Discarding data sent to unconnected session: %s", data);
			return false;
		end
		return session;
	end
	local filter = initialize_filters(session);
	local w = conn.write;
	session.send = function (t)
		if t.name then
			t = filter("stanzas/out", t);
		end
		if t then
			t = filter("bytes/out", tostring(t));
			if t then
				local ret, err = w(conn, t);
				if not ret then
					session.log("debug", "Error writing to connection: %s", err);
					return false, err;
				end
			end
		end
		return true;
	end
	return session;
end

return {
	new = new_session;
	set_id = set_id;
	set_logger = set_logger;
	set_conn = set_conn;
	set_send = set_send;
}