File

mod_tls: Enable Prosody's certificate checking for incoming s2s connections (fixes #1916) (thanks Damian, Zash) Various options in Prosody allow control over the behaviour of the certificate verification process For example, some deployments choose to allow falling back to traditional "dialback" authentication (XEP-0220), while others verify via DANE, hard-coded fingerprints, or other custom plugins. Implementing this flexibility requires us to override OpenSSL's default certificate verification, to allow Prosody to verify the certificate itself, apply custom policies and make decisions based on the outcome. To enable our custom logic, we have to suppress OpenSSL's default behaviour of aborting the connection with a TLS alert message. With LuaSec, this can be achieved by using the verifyext "lsec_continue" flag. We also need to use the lsec_ignore_purpose flag, because XMPP s2s uses server certificates as "client" certificates (for mutual TLS verification in outgoing s2s connections). Commit 99d2100d2918 moved these settings out of the defaults and into mod_s2s, because we only really need these changes for s2s, and they should be opt-in, rather than automatically applied to all TLS services we offer. That commit was incomplete, because it only added the flags for incoming direct TLS connections. StartTLS connections are handled by mod_tls, which was not applying the lsec_* flags. It previously worked because they were already in the defaults. This resulted in incoming s2s connections with "invalid" certificates being aborted early by OpenSSL, even if settings such as `s2s_secure_auth = false` or DANE were present in the config. Outgoing s2s connections inherit verify "none" from the defaults, which means OpenSSL will receive the cert but will not terminate the connection when it is deemed invalid. This means we don't need lsec_continue there, and we also don't need lsec_ignore_purpose (because the remote peer is a "server"). Wondering why we can't just use verify "none" for incoming s2s? It's because in that mode, OpenSSL won't request a certificate from the peer for incoming connections. Setting verify "peer" is how you ask OpenSSL to request a certificate from the client, but also what triggers its built-in verification.

-- Generate util/dnsregistry.lua from IANA HTTP status code registry
if not pcall(require, "prosody.loader") then
	pcall(require, "loader");
end
local xml = require "prosody.util.xml";
local registries = xml.parse(io.read("*a"), { allow_processing_instructions = true });

print("-- Source: https://www.iana.org/assignments/dns-parameters/dns-parameters.xml");
print(os.date("-- Generated on %Y-%m-%d"))

local registry_mapping = {
	["dns-parameters-2"] = "classes";
	["dns-parameters-4"] = "types";
	["dns-parameters-6"] = "errors";
};

print("return {");
for registry in registries:childtags("registry") do
	local registry_name = registry_mapping[registry.attr.id];
	if registry_name then
		print("\t" .. registry_name .. " = {");
		local duplicates = {};
		for record in registry:childtags("record") do
			local record_name = record:get_child_text("name");
			local record_type = record:get_child_text("type");
			local record_desc = record:get_child_text("description");
			local record_code = tonumber(record:get_child_text("value"));

			if tostring(record):lower():match("reserved") or tostring(record):lower():match("unassigned") then
				record_code = nil;
			end

			if registry_name == "classes" and record_code then
				record_type = record_desc and record_desc:match("%((%w+)%)$")
				if record_type then
					print(("\t\t[%q] = %d; [%d] = %q;"):format(record_type, record_code, record_code, record_type))
				end
			elseif registry_name == "types" and record_type and record_code then
				print(("\t\t[%q] = %d; [%d] = %q;"):format(record_type, record_code, record_code, record_type))
			elseif registry_name == "errors" and record_code and record_name then
				local dup = duplicates[record_code] and "-- " or "";
				print(("\t\t%s[%d] = %q; [%q] = %q;"):format(dup, record_code, record_name, record_name, record_desc or record_name));
				duplicates[record_code] = true;
			end
		end
		print("\t};");
	end
end
print("};");