Software /
code /
prosody
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 |
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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; }