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plugins/mod_net_multiplex.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 | 9465:876171084ea3 |
child | 10465:09697a673015 |
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module:set_global(); local max_buffer_len = module:get_option_number("multiplex_buffer_size", 1024); local portmanager = require "core.portmanager"; local available_services = {}; local function add_service(service) local multiplex_pattern = service.multiplex and service.multiplex.pattern; if multiplex_pattern then module:log("debug", "Adding multiplex service %q with pattern %q", service.name, multiplex_pattern); available_services[service] = multiplex_pattern; else module:log("debug", "Service %q is not multiplex-capable", service.name); end end module:hook("service-added", function (event) add_service(event.service); end); module:hook("service-removed", function (event) available_services[event.service] = nil; end); for _, services in pairs(portmanager.get_registered_services()) do for _, service in ipairs(services) do add_service(service); end end local buffers = {}; local listener = { default_mode = "*a" }; function listener.onconnect() end function listener.onincoming(conn, data) if not data then return; end local buf = buffers[conn]; buf = buf and buf..data or data; for service, multiplex_pattern in pairs(available_services) do if buf:match(multiplex_pattern) then module:log("debug", "Routing incoming connection to %s", service.name); local next_listener = service.listener; conn:setlistener(next_listener); local onconnect = next_listener.onconnect; if onconnect then onconnect(conn) end return next_listener.onincoming(conn, buf); end end if #buf > max_buffer_len then -- Give up conn:close(); else buffers[conn] = buf; end end function listener.ondisconnect(conn) buffers[conn] = nil; -- warn if no buffer? end listener.ondetach = listener.ondisconnect; module:provides("net", { name = "multiplex"; config_prefix = ""; listener = listener; }); module:provides("net", { name = "multiplex_ssl"; config_prefix = "ssl"; encryption = "ssl"; listener = listener; });