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plugins/mod_legacyauth.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 | 10557:e1cb869e2f6c |
child | 12328:a80314101bc6 |
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-- Prosody IM -- Copyright (C) 2008-2010 Matthew Wild -- Copyright (C) 2008-2010 Waqas Hussain -- -- This project is MIT/X11 licensed. Please see the -- COPYING file in the source package for more information. -- local st = require "util.stanza"; local t_concat = table.concat; local secure_auth_only = module:get_option("c2s_require_encryption", module:get_option("require_encryption")) or not(module:get_option("allow_unencrypted_plain_auth")); local sessionmanager = require "core.sessionmanager"; local usermanager = require "core.usermanager"; local nodeprep = require "util.encodings".stringprep.nodeprep; local resourceprep = require "util.encodings".stringprep.resourceprep; module:add_feature("jabber:iq:auth"); module:hook("stream-features", function(event) local origin, features = event.origin, event.features; if secure_auth_only and not origin.secure then -- Sorry, not offering to insecure streams! return; elseif not origin.username then features:tag("auth", {xmlns='http://jabber.org/features/iq-auth'}):up(); end end); module:hook("stanza/iq/jabber:iq:auth:query", function(event) local session, stanza = event.origin, event.stanza; if session.type ~= "c2s_unauthed" then (session.sends2s or session.send)(st.error_reply(stanza, "cancel", "service-unavailable", "Legacy authentication is only allowed for unauthenticated client connections.")); return true; end if secure_auth_only and not session.secure then session.send(st.error_reply(stanza, "modify", "not-acceptable", "Encryption (SSL or TLS) is required to connect to this server")); return true; end local query = stanza.tags[1]; local username = query:get_child("username"); local password = query:get_child("password"); local resource = query:get_child("resource"); if not (username and password and resource) then local reply = st.reply(stanza); session.send(reply:query("jabber:iq:auth") :tag("username"):up() :tag("password"):up() :tag("resource"):up()); else username, password, resource = t_concat(username), t_concat(password), t_concat(resource); username = nodeprep(username); resource = resourceprep(resource) if not (username and resource) then session.send(st.error_reply(stanza, "modify", "bad-request")); return true; end if usermanager.test_password(username, session.host, password) then -- Authentication successful! local success, err = sessionmanager.make_authenticated(session, username); if success then local err_type, err_msg; success, err_type, err, err_msg = sessionmanager.bind_resource(session, resource); if not success then session.send(st.error_reply(stanza, err_type, err, err_msg)); session.username, session.type = nil, "c2s_unauthed"; -- FIXME should this be placed in sessionmanager? return true; elseif resource ~= session.resource then -- server changed resource, not supported by legacy auth session.send(st.error_reply(stanza, "cancel", "conflict", "The requested resource could not be assigned to this session.")); session:close(); -- FIXME undo resource bind and auth instead of closing the session? return true; end session.send(st.reply(stanza)); else session.send(st.error_reply(stanza, "auth", "not-authorized", err)); end else session.send(st.error_reply(stanza, "auth", "not-authorized")); end end return true; end);