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plugins/mod_message.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> |
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date | Mon, 10 Jan 2022 18:23:54 +0100 |
parent | 8728:41c959c5c84b |
child | 11482:671f6b867e0d |
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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 full_sessions = prosody.full_sessions; local bare_sessions = prosody.bare_sessions; local st = require "util.stanza"; local jid_bare = require "util.jid".bare; local jid_split = require "util.jid".split; local user_exists = require "core.usermanager".user_exists; local function process_to_bare(bare, origin, stanza) local user = bare_sessions[bare]; local t = stanza.attr.type; if t == "error" then return true; -- discard elseif t == "groupchat" then origin.send(st.error_reply(stanza, "cancel", "service-unavailable")); elseif t == "headline" then if user and stanza.attr.to == bare then for _, session in pairs(user.sessions) do if session.presence and session.priority >= 0 then session.send(stanza); end end end -- current policy is to discard headlines if no recipient is available else -- chat or normal message if user then -- some resources are connected local recipients = user.top_resources; if recipients then local sent; for i=1,#recipients do sent = recipients[i].send(stanza) or sent; end if sent then return true; end end end -- no resources are online local node, host = jid_split(bare); local ok if user_exists(node, host) then ok = module:fire_event('message/offline/handle', { username = node; origin = origin, stanza = stanza, }); end if not ok then origin.send(st.error_reply(stanza, "cancel", "service-unavailable")); end end return true; end module:hook("message/full", function(data) -- message to full JID received local origin, stanza = data.origin, data.stanza; local session = full_sessions[stanza.attr.to]; if session and session.send(stanza) then return true; else -- resource not online return process_to_bare(jid_bare(stanza.attr.to), origin, stanza); end end, -1); module:hook("message/bare", function(data) -- message to bare JID received local origin, stanza = data.origin, data.stanza; return process_to_bare(stanza.attr.to or (origin.username..'@'..origin.host), origin, stanza); end, -1); module:add_feature("msgoffline");