Software / code / prosody
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spec/util_xmppstream_spec.lua @ 13801:a5d5fefb8b68 13.0
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.
| author | Matthew Wild <mwild1@gmail.com> |
|---|---|
| date | Tue, 01 Apr 2025 17:26:56 +0100 |
| parent | 9021:548ba4090012 |
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local xmppstream = require "util.xmppstream"; describe("util.xmppstream", function() local function test(xml, expect_success, ex) local stanzas = {}; local session = { notopen = true }; local callbacks = { stream_ns = "streamns"; stream_tag = "stream"; default_ns = "stanzans"; streamopened = function (_session) assert.are.equal(session, _session); assert.are.equal(session.notopen, true); _session.notopen = nil; return true; end; handlestanza = function (_session, stanza) assert.are.equal(session, _session); assert.are.equal(_session.notopen, nil); table.insert(stanzas, stanza); end; streamclosed = function (_session) assert.are.equal(session, _session); assert.are.equal(_session.notopen, nil); _session.notopen = nil; end; } if type(ex) == "table" then for k, v in pairs(ex) do if k ~= "_size_limit" then callbacks[k] = v; end end end local stream = xmppstream.new(session, callbacks, ex and ex._size_limit or nil); local ok, err = pcall(function () assert(stream:feed(xml)); end); if ok and type(expect_success) == "function" then expect_success(stanzas); end assert.are.equal(not not ok, not not expect_success, "Expected "..(expect_success and ("success ("..tostring(err)..")") or "failure")); end local function test_stanza(stanza, expect_success, ex) return test([[<stream:stream xmlns:stream="streamns" xmlns="stanzans">]]..stanza, expect_success, ex); end describe("#new()", function() it("should work", function() test([[<stream:stream xmlns:stream="streamns"/>]], true); test([[<stream xmlns="streamns"/>]], true); -- Incorrect stream tag name should be rejected test([[<stream1 xmlns="streamns"/>]], false); -- Incorrect stream namespace should be rejected test([[<stream xmlns="streamns1"/>]], false); -- Invalid XML should be rejected test("<>", false); test_stanza("<message/>", function (stanzas) assert.are.equal(#stanzas, 1); assert.are.equal(stanzas[1].name, "message"); end); test_stanza("< message>>>>/>\n", false); test_stanza([[<x xmlns:a="b"> <y xmlns:a="c"> <a:z/> </y> <a:z/> </x>]], function (stanzas) assert.are.equal(#stanzas, 1); local s = stanzas[1]; assert.are.equal(s.name, "x"); assert.are.equal(#s.tags, 2); assert.are.equal(s.tags[1].name, "y"); assert.are.equal(s.tags[1].attr.xmlns, nil); assert.are.equal(s.tags[1].tags[1].name, "z"); assert.are.equal(s.tags[1].tags[1].attr.xmlns, "c"); assert.are.equal(s.tags[2].name, "z"); assert.are.equal(s.tags[2].attr.xmlns, "b"); assert.are.equal(s.namespaces, nil); end); end); end); it("should allow an XML declaration", function () test([[<?xml version="1.0" encoding="UTF-8"?><stream xmlns="streamns"/>]], true); test([[<?xml version="1.0" encoding="UTF-8" standalone="yes" ?><stream xmlns="streamns"/>]], true); test([[<?xml version="1.0" encoding="utf-8" ?><stream xmlns="streamns"/>]], true); end); it("should not accept XML versions other than 1.0", function () test([[<?xml version="1.1" encoding="utf-8" ?><stream xmlns="streamns"/>]], false); end); it("should not allow a misplaced XML declaration", function () test([[<stream xmlns="streamns"><?xml version="1.0" encoding="UTF-8"?></stream>]], false); end); describe("should forbid restricted XML:", function () it("comments", function () test_stanza("<!-- hello world -->", false); end); it("DOCTYPE", function () test([[<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE stream SYSTEM "mydtd.dtd">]], false); end); it("incorrect encoding specification", function () -- This is actually caught by the underlying XML parser test([[<?xml version="1.0" encoding="UTF-16"?><stream xmlns="streamns"/>]], false); end); it("non-UTF8 encodings: ISO-8859-1", function () test([[<?xml version="1.0" encoding="ISO-8859-1"?><stream xmlns="streamns"/>]], false); end); it("non-UTF8 encodings: UTF-16", function () -- <?xml version="1.0" encoding="UTF-16"?><stream xmlns="streamns"/> -- encoded into UTF-16 local hx = ([[fffe3c003f0078006d006c002000760065007200730069006f006e003d00 220031002e0030002200200065006e0063006f00640069006e0067003d00 22005500540046002d003100360022003f003e003c007300740072006500 61006d00200078006d006c006e0073003d00220073007400720065006100 6d006e00730022002f003e00]]):gsub("%x%x", function (c) return string.char(tonumber(c, 16)); end); test(hx, false); end); it("processing instructions", function () test([[<stream xmlns="streamns"><?xml-stylesheet type="text/xsl" href="style.xsl"?></stream>]], false); end); end); end);