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f315edc39f3d

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6221:f315edc39f3d

mod_s2s_auth_dane: Remove because broken, Prosody supports DANE now
author Kim Alvefur <zash@zash.se>
date Wed, 02 Apr 2025 16:25:33 +0200
parents 6220:c83bfcc6ac0a
children 6222:963c16e417d6
files mod_s2s_auth_dane/README.md mod_s2s_auth_dane/mod_s2s_auth_dane.lua
diffstat 2 files changed, 7 insertions(+), 437 deletions(-) [+]
line wrap: on
line diff
--- a/mod_s2s_auth_dane/README.md	Mon Mar 31 13:24:44 2025 +0200
+++ b/mod_s2s_auth_dane/README.md	Wed Apr 02 16:25:33 2025 +0200
@@ -1,10 +1,16 @@
 ---
 labels:
-- Stage-Broken
+- Stage-Obsolete
 - Type-S2SAuth
 summary: S2S authentication using DANE
 ...
 
+::: {.alert .alert-warning}
+This module no longer works with recent versions of Prosody.
+
+However, Prosody as of [13.0.0](//prosody.im/doc/release/13.0.0) ships with native support for [DANE](//prosody.im/doc/dnssec).
+:::
+
 Introduction
 ============
 
--- a/mod_s2s_auth_dane/mod_s2s_auth_dane.lua	Mon Mar 31 13:24:44 2025 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,436 +0,0 @@
--- 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 unpack = table.unpack or _G.unpack;
-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
-
-local new_dane = module:get_option_boolean("use_dane", false);
-
-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
-
-	if not new_dane then
-		-- 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);
-	end
-
-	-- 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
-