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plugins/muc/util.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 | 9603:4897bd63f624 |
child | 10713:38159b9adf9f |
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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 _M = {}; _M.valid_affiliations = { outcast = -1; none = 0; member = 1; admin = 2; owner = 3; }; _M.valid_roles = { none = 0; visitor = 1; participant = 2; moderator = 3; }; local kickable_error_conditions = { ["gone"] = true; ["internal-server-error"] = true; ["item-not-found"] = true; ["jid-malformed"] = true; ["recipient-unavailable"] = true; ["redirect"] = true; ["remote-server-not-found"] = true; ["remote-server-timeout"] = true; ["service-unavailable"] = true; ["malformed error"] = true; }; function _M.is_kickable_error(stanza) local cond = select(2, stanza:get_error()) or "malformed error"; return kickable_error_conditions[cond]; end local muc_x_filters = { ["http://jabber.org/protocol/muc"] = true; ["http://jabber.org/protocol/muc#user"] = true; } local function muc_x_filter(tag) if muc_x_filters[tag.attr.xmlns] then return nil; end return tag; end function _M.filter_muc_x(stanza) return stanza:maptags(muc_x_filter); end function _M.only_with_min_role(role) local min_role_value = _M.valid_roles[role]; return function (nick, occupant) --luacheck: ignore 212/nick if _M.valid_roles[occupant.role or "none"] >= min_role_value then return true; end end; end return _M;