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plugins/muc/members_only.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 | 11545:7b8a482f4efd |
child | 11560:3bbb1af92514 |
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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 muc_util = module:require "muc/util"; local valid_affiliations = muc_util.valid_affiliations; local function get_members_only(room) return room._data.members_only; end local function set_members_only(room, members_only) members_only = members_only and true or nil; if room._data.members_only == members_only then return false; end room._data.members_only = members_only; if members_only then --[[ If as a result of a change in the room configuration the room type is changed to members-only but there are non-members in the room, the service MUST remove any non-members from the room and include a status code of 322 in the presence unavailable stanzas sent to those users as well as any remaining occupants. ]] local occupants_changed = {}; for _, occupant in room:each_occupant() do local affiliation = room:get_affiliation(occupant.bare_jid); if valid_affiliations[affiliation or "none"] <= valid_affiliations.none then occupant.role = nil; room:save_occupant(occupant); occupants_changed[occupant] = true; end end local x = st.stanza("x", {xmlns = "http://jabber.org/protocol/muc#user"}) :tag("status", {code="322"}):up(); for occupant in pairs(occupants_changed) do room:publicise_occupant_status(occupant, x); module:fire_event("muc-occupant-left", {room = room; nick = occupant.nick; occupant = occupant;}); end end return true; end local function get_allow_member_invites(room) return room._data.allow_member_invites; end -- Allows members to invite new members into a members-only room, -- effectively creating an invite-only room local function set_allow_member_invites(room, allow_member_invites) allow_member_invites = allow_member_invites and true or nil; if room._data.allow_member_invites == allow_member_invites then return false; end room._data.allow_member_invites = allow_member_invites; return true; end module:hook("muc-disco#info", function(event) local members_only_room = not not get_members_only(event.room); local members_can_invite = not not get_allow_member_invites(event.room); event.reply:tag("feature", {var = members_only_room and "muc_membersonly" or "muc_open"}):up(); table.insert(event.form, { name = "{http://prosody.im/protocol/muc}roomconfig_allowmemberinvites"; label = "Allow members to invite new members"; type = "boolean"; value = members_can_invite; }); table.insert(event.form, { name = "muc#roomconfig_allowinvites"; label = "Allow users to invite other users"; type = "boolean"; value = not members_only_room or members_can_invite; }); end); module:hook("muc-config-form", function(event) table.insert(event.form, { name = "muc#roomconfig_membersonly"; type = "boolean"; label = "Only allow members to join"; desc = "Enable this to only allow access for room owners, admins and members"; value = get_members_only(event.room); }); table.insert(event.form, { name = "{http://prosody.im/protocol/muc}roomconfig_allowmemberinvites"; type = "boolean"; label = "Allow members to invite new members"; value = get_allow_member_invites(event.room); }); end, 90-3); module:hook("muc-config-submitted/muc#roomconfig_membersonly", function(event) if set_members_only(event.room, event.value) then event.status_codes["104"] = true; end end); module:hook("muc-config-submitted/{http://prosody.im/protocol/muc}roomconfig_allowmemberinvites", function(event) if set_allow_member_invites(event.room, event.value) then event.status_codes["104"] = true; end end); -- No affiliation => role of "none" module:hook("muc-get-default-role", function(event) if not event.affiliation and get_members_only(event.room) then return false; end end, 2); -- registration required for entering members-only room module:hook("muc-occupant-pre-join", function(event) local room = event.room; if get_members_only(room) then local stanza = event.stanza; local affiliation = room:get_affiliation(stanza.attr.from); if valid_affiliations[affiliation or "none"] <= valid_affiliations.none then local reply = st.error_reply(stanza, "auth", "registration-required"):up(); reply.tags[1].attr.code = "407"; event.origin.send(reply:tag("x", {xmlns = "http://jabber.org/protocol/muc"})); return true; end end end, -5); -- Invitation privileges in members-only rooms SHOULD be restricted to room admins; -- if a member without privileges to edit the member list attempts to invite another user -- the service SHOULD return a <forbidden/> error to the occupant module:hook("muc-pre-invite", function(event) local room = event.room; if get_members_only(room) then local stanza = event.stanza; local inviter_affiliation = room:get_affiliation(stanza.attr.from) or "none"; local required_affiliation = room._data.allow_member_invites and "member" or "admin"; if valid_affiliations[inviter_affiliation] < valid_affiliations[required_affiliation] then event.origin.send(st.error_reply(stanza, "auth", "forbidden")); return true; end end end); -- When an invite is sent; add an affiliation for the invitee module:hook("muc-invite", function(event) local room = event.room; if get_members_only(room) then local stanza = event.stanza; local invitee = stanza.attr.to; local affiliation = room:get_affiliation(invitee); local invited_unaffiliated = valid_affiliations[affiliation or "none"] <= valid_affiliations.none; if invited_unaffiliated then local from = stanza:get_child("x", "http://jabber.org/protocol/muc#user") :get_child("invite").attr.from; module:log("debug", "%s invited %s into members only room %s, granting membership", from, invitee, room.jid); -- This might fail; ignore for now room:set_affiliation(true, invitee, "member", "Invited by " .. from); room:save(); end end end); return { get = get_members_only; set = set_members_only; get_allow_member_invites = get_allow_member_invites; set_allow_member_invites = set_allow_member_invites; };