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plugins/mod_scansion_record.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 | 9619:7172077c0a53 |
child | 10718:d229e4d31598 |
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local names = { "Romeo", "Juliet", "Mercutio", "Tybalt", "Benvolio" }; local devices = { "", "phone", "laptop", "tablet", "toaster", "fridge", "shoe" }; local users = {}; local filters = require "util.filters"; local id = require "util.id"; local dt = require "util.datetime"; local dm = require "util.datamanager"; local st = require "util.stanza"; local record_id = id.medium():lower(); local record_date = os.date("%Y%b%d"):lower(); local header_file = dm.getpath(record_id, "scansion", record_date, "scs", true); local record_file = dm.getpath(record_id, "scansion", record_date, "log", true); local head = io.open(header_file, "w"); local scan = io.open(record_file, "w+"); local function record(string) scan:write(string); end local function record_header(string) head:write(string); end local function record_object(class, name, props) head:write(("[%s] %s\n"):format(class, name)); for k,v in pairs(props) do head:write(("\t%s: %s\n"):format(k, v)); end head:write("\n"); end local function record_event(session, event) record(session.scansion_id.." "..event.."\n\n"); end local function record_stanza(stanza, session, verb) local flattened = tostring(stanza):gsub("><", ">\n\t<"); -- TODO Proper prettyprinting with indentation record(session.scansion_id.." "..verb..":\n\t"..flattened.."\n\n"); end local function record_stanza_in(stanza, session) if stanza.attr.xmlns == nil then local copy = st.clone(stanza); copy.attr.from = nil; record_stanza(copy, session, "sends") end return stanza; end local function record_stanza_out(stanza, session) if stanza.attr.xmlns == nil then if not (stanza.name == "iq" and stanza:get_child("bind", "urn:ietf:params:xml:ns:xmpp-bind")) then local copy = st.clone(stanza); if copy.attr.to == session.full_jid then copy.attr.to = nil; end record_stanza(copy, session, "receives"); end end return stanza; end module:hook("resource-bind", function (event) local session = event.session; if not users[session.username] then users[session.username] = { character = table.remove(names, 1) or id.short(); devices = {}; n_devices = 0; }; end local user = users[session.username]; local device = user.devices[session.resource]; if not device then user.n_devices = user.n_devices + 1; device = devices[user.n_devices] or ("device"..id.short()); user.devices[session.resource] = device; end session.scansion_character = user.character; session.scansion_device = device; session.scansion_id = user.character..(device ~= "" and "'s "..device or device); record_object("Client", session.scansion_id, { jid = session.full_jid, password = "password", }); module:log("info", "Connected: %s", session.scansion_id); record_event(session, "connects"); filters.add_filter(session, "stanzas/in", record_stanza_in); filters.add_filter(session, "stanzas/out", record_stanza_out); end); module:hook("resource-unbind", function (event) local session = event.session; if session.scansion_id then record_event(session, "disconnects"); end end) record_header("# mod_scansion_record on host '"..module.host.."' recording started "..dt.datetime().."\n\n"); record[[ ----- ]] module:hook_global("server-stopping", function () record("# recording ended on "..dt.datetime().."\n"); module:log("info", "Scansion recording available in %s", header_file); end); prosody.events.add_handler("server-cleanup", function () scan:seek("set", 0); for line in scan:lines() do head:write(line, "\n"); end scan:close(); os.remove(record_file); head:close() end);