File

plugins/mod_dialback.lua @ 12591:494577d883ff

util.table: Fix inaccurate comment Probably a duplicate of the comment next to Lmove, recorded by mistake Lpack can probably be removed at some point in the near future once we are confident it is not used anywhere.
author Kim Alvefur <zash@zash.se>
date Mon, 11 Jul 2022 20:02:10 +0200
parent 11679:d9499b7bcd54
child 12977:74b9e05af71e
line wrap: on
line source

-- 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 hosts = _G.hosts;

local log = module._log;

local st = require "util.stanza";
local sha256_hash = require "util.hashes".sha256;
local sha256_hmac = require "util.hashes".hmac_sha256;
local secure_equals = require "util.hashes".equals;
local nameprep = require "util.encodings".stringprep.nameprep;
local uuid_gen = require"util.uuid".generate;

local xmlns_stream = "http://etherx.jabber.org/streams";

local dialback_requests = setmetatable({}, { __mode = 'v' });

local dialback_secret = sha256_hash(module:get_option_string("dialback_secret", uuid_gen()), true);

function module.save()
	return { dialback_secret = dialback_secret };
end

function module.restore(state)
	dialback_secret = state.dialback_secret;
end

function generate_dialback(id, to, from)
	return sha256_hmac(dialback_secret, to .. ' ' .. from .. ' ' .. id, true);
end

function initiate_dialback(session)
	-- generate dialback key
	session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
	session.sends2s(st.stanza("db:result", { from = session.from_host, to = session.to_host }):text(session.dialback_key));
	session.log("debug", "sent dialback key on outgoing s2s stream");
end

function verify_dialback(id, to, from, key)
	return secure_equals(key, generate_dialback(id, to, from));
end

module:hook("stanza/jabber:server:dialback:verify", function(event)
	local origin, stanza = event.origin, event.stanza;

	if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
		-- We are being asked to verify the key, to ensure it was generated by us
		origin.log("debug", "verifying that dialback key is ours...");
		local attr = stanza.attr;
		if attr.type then
			module:log("warn", "Ignoring incoming session from %s claiming a dialback key for %s is %s",
				origin.from_host or "(unknown)", attr.from or "(unknown)", attr.type);
			return true;
		end
		-- COMPAT: Grr, ejabberd breaks this one too?? it is black and white in XEP-220 example 34
		--if attr.from ~= origin.to_host then error("invalid-from"); end
		local type;
		if verify_dialback(attr.id, attr.from, attr.to, stanza[1]) then
			type = "valid"
		else
			type = "invalid"
			origin.log("warn", "Asked to verify a dialback key that was incorrect. An imposter is claiming to be %s?", attr.to);
		end
		origin.log("debug", "verified dialback key... it is %s", type);
		origin.sends2s(st.stanza("db:verify", { from = attr.to, to = attr.from, id = attr.id, type = type }):text(stanza[1]));
		return true;
	end
end);

module:hook("stanza/jabber:server:dialback:result", function(event)
	local origin, stanza = event.origin, event.stanza;

	if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
		-- They want to be identified through dialback
		-- We need to check the key with the Authoritative server
		local attr = stanza.attr;
		if not attr.to or not attr.from then
			origin.log("debug", "Missing Dialback addressing (from=%q, to=%q)", attr.from, attr.to);
			origin:close("improper-addressing");
			return true;
		end
		local to, from = nameprep(attr.to), nameprep(attr.from);

		if not hosts[to] then
			-- Not a host that we serve
			origin.log("warn", "%s tried to connect to %s, which we don't serve", from, to);
			origin:close("host-unknown");
			return true;
		elseif not from then
			origin:close("improper-addressing");
			return true;
		end


		origin.hosts[from] = { dialback_key = stanza[1] };

		dialback_requests[from.."/"..origin.streamid] = origin;

		-- COMPAT: ejabberd, gmail and perhaps others do not always set 'to' and 'from'
		-- on streams. We fill in the session's to/from here instead.
		if not origin.from_host then
			origin.from_host = from;
		end
		if not origin.to_host then
			origin.to_host = to;
		end

		origin.log("debug", "asking %s if key %s belongs to them", from, stanza[1]);
		module:fire_event("route/remote", {
			from_host = to, to_host = from;
			stanza = st.stanza("db:verify", { from = to, to = from, id = origin.streamid }):text(stanza[1]);
		});
		return true;
	end
end);

module:hook("stanza/jabber:server:dialback:verify", function(event)
	local origin, stanza = event.origin, event.stanza;

	if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
		local attr = stanza.attr;
		local dialback_verifying = dialback_requests[attr.from.."/"..(attr.id or "")];
		if dialback_verifying and attr.from == origin.to_host then
			local valid;
			if attr.type == "valid" then
				module:fire_event("s2s-authenticated", { session = dialback_verifying, host = attr.from, mechanism = "dialback" });
				valid = "valid";
			else
				-- Warn the original connection that is was not verified successfully
				log("warn", "authoritative server for %s denied the key", attr.from or "(unknown)");
				valid = "invalid";
			end
			if dialback_verifying.destroyed then
				log("warn", "Incoming s2s session %s was closed in the meantime, so we can't notify it of the dialback result",
					tostring(dialback_verifying):match("%w+$"));
			else
				dialback_verifying.sends2s(
						st.stanza("db:result", { from = attr.to, to = attr.from, id = attr.id, type = valid })
								:text(dialback_verifying.hosts[attr.from].dialback_key));
			end
			dialback_requests[attr.from.."/"..(attr.id or "")] = nil;
		end
		return true;
	end
end);

module:hook("stanza/jabber:server:dialback:result", function(event)
	local origin, stanza = event.origin, event.stanza;

	if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
		-- Remote server is telling us whether we passed dialback

		local attr = stanza.attr;
		if not hosts[attr.to] then
			origin:close("host-unknown");
			return true;
		elseif hosts[attr.to].s2sout[attr.from] ~= origin then
			-- This isn't right
			origin:close("invalid-id");
			return true;
		end
		if stanza.attr.type == "valid" then
			module:fire_event("s2s-authenticated", { session = origin, host = attr.from, mechanism = "dialback" });
		else
			origin:close("not-authorized", "dialback authentication failed");
		end
		return true;
	end
end);

module:hook_tag("urn:ietf:params:xml:ns:xmpp-sasl", "failure", function (origin, stanza) -- luacheck: ignore 212/stanza
	if origin.external_auth == "failed" then
		module:log("debug", "SASL EXTERNAL failed, falling back to dialback");
		initiate_dialback(origin);
		return true;
	end
end, 100);

module:hook_tag(xmlns_stream, "features", function (origin, stanza) -- luacheck: ignore 212/stanza
	if not origin.external_auth or origin.external_auth == "failed" then
		module:log("debug", "Initiating dialback...");
		initiate_dialback(origin);
		return true;
	end
end, 100);

module:hook("s2sout-authenticate-legacy", function (event)
	module:log("debug", "Initiating dialback...");
	initiate_dialback(event.origin);
	return true;
end, 100);

-- Offer dialback to incoming hosts
module:hook("s2s-stream-features", function (data)
	data.features:tag("dialback", { xmlns='urn:xmpp:features:dialback' }):up();
end);