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mod_s2s_auth_dane/mod_s2s_auth_dane.lua @ 4421:94805a7e7b30
mod_invites: rework CLI parsing to support groups
To make this sensible, the code had to move from rather simple
parsing to something which looks more like getopt or your typical
shell script.
author | Jonas Schäfer <jonas@wielicki.name> |
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date | Sun, 31 Jan 2021 19:16:36 +0100 |
parent | 2869:77498ea07795 |
child | 4490:cf2bdb2aaa57 |
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-- mod_s2s_auth_dane -- Copyright (C) 2013-2014 Kim Alvefur -- -- This file is MIT/X11 licensed. -- -- Implements DANE and Secure Delegation using DNS SRV as described in -- http://tools.ietf.org/html/draft-miller-xmpp-dnssec-prooftype -- -- Known issues: -- Could be done much cleaner if mod_s2s was using util.async -- -- TODO Things to test/handle: -- Negative or bogus answers -- No encryption offered -- Different hostname before and after STARTTLS - mod_s2s should complain -- Interaction with Dialback -- -- luacheck: ignore module module:set_global(); local have_async, async = pcall(require, "util.async"); local noop = function () end local type = type; local t_insert = table.insert; local set = require"util.set"; local dns_lookup = require"net.adns".lookup; local hashes = require"util.hashes"; local base64 = require"util.encodings".base64; local idna_to_ascii = require "util.encodings".idna.to_ascii; local idna_to_unicode = require"util.encodings".idna.to_unicode; local nameprep = require"util.encodings".stringprep.nameprep; local cert_verify_identity = require "util.x509".verify_identity; do local net_dns = require"net.dns"; if not net_dns.types or not net_dns.types[52] then module:log("error", "No TLSA support available, DANE will not be supported"); return end end local pat = "%-%-%-%-%-BEGIN ([A-Z ]+)%-%-%-%-%-\r?\n".. "([0-9A-Za-z=+/\r\n]*)\r?\n%-%-%-%-%-END %1%-%-%-%-%-"; local function pem2der(pem) local typ, data = pem:match(pat); if typ and data then return base64.decode(data), typ; end end local use_map = { ["DANE-EE"] = 3; ["DANE-TA"] = 2; ["PKIX-EE"] = 1; ["PKIX-CA"] = 0 } local implemented_uses = set.new { "DANE-EE", "PKIX-EE" }; do local cert_mt = debug.getregistry()["SSL:Certificate"]; if cert_mt and cert_mt.__index.issued then -- Need cert:issued() for these implemented_uses:add("DANE-TA"); implemented_uses:add("PKIX-CA"); else module:log("debug", "The cert:issued() method is unavailable, DANE-TA and PKIX-CA can't be enabled"); end if not cert_mt.__index.pubkey then module:log("debug", "The cert:pubkey() method is unavailable, the SPKI usage can't be supported"); end end local configured_uses = module:get_option_set("dane_uses", { "DANE-EE", "DANE-TA" }); local enabled_uses = set.intersection(implemented_uses, configured_uses) / function(use) return use_map[use] end; local unsupported = configured_uses - implemented_uses; if not unsupported:empty() then module:log("warn", "Unable to support DANE uses %s", tostring(unsupported)); end -- Find applicable TLSA records -- Takes a s2sin/out and a callback local function dane_lookup(host_session, cb) cb = cb or noop; local log = host_session.log or module._log; if host_session.dane ~= nil then return end -- Has already done a lookup if host_session.direction == "incoming" then if not host_session.from_host then log("debug", "Session doesn't have a 'from' host set"); return; end -- We don't know what hostname or port to use for Incoming connections -- so we do a SRV lookup and then request TLSA records for each SRV -- Most servers will probably use the same certificate on outgoing -- and incoming connections, so this should work well local name = host_session.from_host and idna_to_ascii(host_session.from_host); if not name then log("warn", "Could not convert '%s' to ASCII for DNS lookup", tostring(host_session.from_host)); return; end log("debug", "Querying SRV records from _xmpp-server._tcp.%s.", name); host_session.dane = dns_lookup(function (answer, err) host_session.dane = false; -- Mark that we already did the lookup if not answer then log("debug", "Resolver error: %s", tostring(err)); return cb(host_session); end if answer.bogus then log("warn", "Results are bogus!"); -- Bad sign, probably not a good idea to do any fallback here host_session.dane = answer; elseif not answer.secure then log("debug", "Results are not secure"); return cb(host_session); end local n = answer.n or #answer; if n == 0 then -- No SRV records, synthesize fallback host and port -- this may behave oddly for connections in the other direction if -- mod_s2s doesn't keep the answer around answer[1] = { srv = { target = name, port = 5269 } }; n = 1; elseif n == 1 and answer[1].srv.target == '.' then return cb(host_session); -- No service ... This shouldn't happen? end local srv_hosts = { answer = answer }; host_session.srv_hosts = srv_hosts; local dane; for _, record in ipairs(answer) do t_insert(srv_hosts, record.srv); log("debug", "Querying TLSA record for %s:%d", record.srv.target, record.srv.port); dns_lookup(function(dane_answer) log("debug", "Got answer for %s:%d", record.srv.target, record.srv.port); n = n - 1; -- There are three kinds of answers -- Insecure, Secure and Bogus -- -- We collect Secure answers for later use -- -- Insecure (legacy) answers are simply ignored -- -- If we get a Bogus (dnssec error) reply, keep the -- status around. If there were only bogus replies, the -- connection will be aborted. If there were at least -- one non-Bogus reply, we proceed. If none of the -- replies matched, we consider the connection insecure. if (dane_answer.bogus or dane_answer.secure) and not dane then -- The first answer we care about -- For services with only one SRV record, this will be the only one log("debug", "First secure (or bogus) TLSA") dane = dane_answer; elseif dane_answer.bogus then log("debug", "Got additional bogus TLSA") dane.bogus = dane_answer.bogus; elseif dane_answer.secure then log("debug", "Got additional secure TLSA") for _, dane_record in ipairs(dane_answer) do t_insert(dane, dane_record); end end if n == 0 then if dane then host_session.dane = dane; if #dane > 0 and dane.bogus then -- Got at least one non-bogus reply, -- This should trigger a failure if one of them did not match log("warn", "Ignoring bogus replies"); dane.bogus = nil; end if #dane == 0 and dane.bogus == nil then -- Got no usable data host_session.dane = false; end end return cb(host_session); end end, ("_%d._tcp.%s."):format(record.srv.port, record.srv.target), "TLSA"); end end, "_xmpp-server._tcp."..name..".", "SRV"); return true; elseif host_session.direction == "outgoing" then -- Prosody has already done SRV lookups for outgoing session, so check if those are secure local srv_hosts = host_session.srv_hosts; if not ( srv_hosts and srv_hosts.answer and srv_hosts.answer.secure ) then return; -- No secure SRV records, fall back to non-DANE mode -- Empty response were not kept by older mod_s2s/s2sout end -- Do TLSA lookup for currently selected SRV record local srv_choice = srv_hosts[host_session.srv_choice or 0] or { target = idna_to_ascii(host_session.to_host), port = 5269 }; log("debug", "Querying TLSA record for %s:%d", srv_choice.target, srv_choice.port); host_session.dane = dns_lookup(function(answer) if answer and ((answer.secure and #answer > 0) or answer.bogus) then srv_choice.dane = answer; else srv_choice.dane = false; end host_session.dane = srv_choice.dane; return cb(host_session); end, ("_%d._tcp.%s."):format(srv_choice.port, srv_choice.target), "TLSA"); return true; end end local function pause(host_session) host_session.log("debug", "Pausing connection until DANE lookup is completed"); host_session.conn:pause() end local function resume(host_session) host_session.log("debug", "DANE lookup completed, resuming connection"); host_session.conn:resume() end if have_async then function pause(host_session) host_session.log("debug", "Pausing connection until DANE lookup is completed"); local wait, done = async.waiter(); host_session._done_waiting_for_dane = done; wait(); end local function _resume(_, host_session) if host_session._done_waiting_for_dane then host_session.log("debug", "DANE lookup completed, resuming connection"); host_session._done_waiting_for_dane(); host_session._done_waiting_for_dane = nil; end end function resume(host_session) -- Something about the way luaunbound calls callbacks is messed up if host_session._done_waiting_for_dane then module:add_timer(0, _resume, host_session); end end end function module.add_host(module) local function on_new_s2s(event) local host_session = event.origin; if host_session.type == "s2sout" or host_session.type == "s2sin" then return; -- Already authenticated end if host_session.dane ~= nil then return; -- Already done DANE lookup end dane_lookup(host_session, resume); -- Let it run in parallel until we need to check the cert end -- New outgoing connections module:hook("stanza/http://etherx.jabber.org/streams:features", on_new_s2s, 501); module:hook("s2sout-authenticate-legacy", on_new_s2s, 200); -- New incoming connections module:hook("s2s-stream-features", on_new_s2s, 10); module:hook("s2s-authenticated", function(event) local session = event.session; if session.dane and type(session.dane) == "table" and next(session.dane) ~= nil and not session.secure then -- TLSA record but no TLS, not ok. -- TODO Optional? -- Bogus replies should trigger this path -- How does this interact with Dialback? session:close({ condition = "policy-violation", text = "Encrypted server-to-server communication is required but was not " ..((session.direction == "outgoing" and "offered") or "used") }); return false; end -- Cleanup session.srv_hosts = nil; end); end -- Compare one TLSA record against a certificate local function one_dane_check(tlsa, cert, log) local select, match, certdata = tlsa.select, tlsa.match; if select == 0 then certdata = pem2der(cert:pem()); elseif select == 1 and cert.pubkey then certdata = pem2der(cert:pubkey()); else log("warn", "DANE selector %s is unsupported", tlsa:getSelector() or select); return; end if match == 1 then certdata = hashes.sha256(certdata); elseif match == 2 then certdata = hashes.sha512(certdata); elseif match ~= 0 then log("warn", "DANE match rule %s is unsupported", tlsa:getMatchType() or match); return; end if #certdata ~= #tlsa.data then log("warn", "Length mismatch: Cert: %d, TLSA: %d", #certdata, #tlsa.data); end return certdata == tlsa.data; end module:hook("s2s-check-certificate", function(event) local session, cert, host = event.session, event.cert, event.host; if not cert then return end local log = session.log or module._log; local dane = session.dane; if type(dane) ~= "table" then if dane == nil and dane_lookup(session, resume) then pause(session); dane = session.dane; end end if type(dane) == "table" then local match_found, supported_found; for i = 1, #dane do local tlsa = dane[i].tlsa; log("debug", "TLSA #%d: %s", i, tostring(tlsa)) local use = tlsa.use; if enabled_uses:contains(use) then -- DANE-EE or PKIX-EE if use == 3 or use == 1 then -- Should we check if the cert subject matches? local is_match = one_dane_check(tlsa, cert, log); if is_match ~= nil then supported_found = true; end if is_match and use == 1 and session.cert_chain_status ~= "valid" then -- for usage 1, PKIX-EE, the chain has to be valid already log("debug", "PKIX-EE TLSA matches untrusted certificate"); is_match = false; end if is_match then log("info", "DANE validated ok for %s using %s", host, tlsa:getUsage()); session.cert_identity_status = "valid"; if use == 3 then -- DANE-EE, chain status equals DNSSEC chain status session.cert_chain_status = "valid"; end match_found = true; dane.matching = tlsa; break; end -- DANE-TA or PKIX-CA elseif use == 2 or use == 0 then supported_found = true; local chain = session.conn:socket():getpeerchain(); for c = 1, #chain do local cacert = chain[c]; local is_match = one_dane_check(tlsa, cacert, log); if is_match ~= nil then supported_found = true; end if is_match and not cacert:issued(cert, unpack(chain)) then is_match = false; end if is_match and use == 0 and session.cert_chain_status ~= "valid" then -- for usage 0, PKIX-CA, identity and chain has to be valid already is_match = false; end if is_match then log("info", "DANE validated ok for %s using %s", host, tlsa:getUsage()); if use == 2 then -- DANE-TA session.cert_identity_status = "valid"; if cert_verify_identity(host, "xmpp-server", cert) then session.cert_chain_status = "valid"; -- else -- TODO Check against SRV target? end end match_found = true; dane.matching = tlsa; break; end end if match_found then break end end end end if supported_found and not match_found or dane.bogus then -- No TLSA matched or response was bogus local why = "No TLSA matched certificate"; if dane.bogus then why = "Bogus: "..tostring(dane.bogus); end log("warn", "DANE validation failed for %s: %s", host, why); session.cert_identity_status = "invalid"; session.cert_chain_status = "invalid"; end else if session.cert_chain_status == "valid" and session.cert_identity_status ~= "valid" and session.srv_hosts and session.srv_hosts.answer and session.srv_hosts.answer.secure then local srv_hosts, srv_choice, srv_target = session.srv_hosts, session.srv_choice; for i = srv_choice or 1, srv_choice or #srv_hosts do srv_target = session.srv_hosts[i].target:gsub("%.?$",""); log("debug", "Comparing certificate with Secure SRV target %s", srv_target); srv_target = nameprep(idna_to_unicode(srv_target)); if srv_target and cert_verify_identity(srv_target, "xmpp-server", cert) then log("info", "Certificate for %s matches Secure SRV target %s", host, srv_target); session.cert_identity_status = "valid"; return; end end end end end); -- Telnet command if module:get_option_set("modules_enabled", {}):contains("admin_telnet") then module:depends("admin_telnet"); -- Make sure the env is there local def_env = module:shared("admin_telnet/env"); local function annotate(session, line) line = line or {}; table.insert(line, "--"); if session.dane == nil then table.insert(line, "No DANE attempted, probably insecure SRV response"); elseif session.dane == false then table.insert(line, "DANE failed or response was insecure"); elseif type(session.dane) ~= "table" then table.insert(line, "Waiting for DANE records..."); elseif session.dane.matching then table.insert(line, "Matching DANE record:\n| " .. tostring(session.dane.matching)); else table.insert(line, "DANE records:\n| " .. tostring(session.dane)); end return table.concat(line, " "); end function def_env.s2s:show_dane(...) return self:show(..., annotate); end end