Software / code / prosody
File
net/server.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 | 13453:0b48cf880e79 |
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-- 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 function log(level, format, ...) print("net.server", level, format:format(...)); end local default_backend = "select"; local server_type = default_backend; if (prosody and prosody.config_loaded) then default_backend = "epoll"; log = require"prosody.util.logger".init("net.server"); server_type = require"prosody.core.configmanager".get("*", "network_backend") or default_backend; if require"prosody.core.configmanager".get("*", "use_libevent") then server_type = "event"; end elseif pcall(require, "prosody.util.poll") then server_type = "epoll"; end if server_type == "event" then if not pcall(require, "luaevent.core") then log("error", "libevent not found, falling back to %s", default_backend); server_type = default_backend; end end local server; local set_config; if server_type == "event" then server = require "prosody.net.server_event"; local defaults = {}; for k,v in pairs(server.cfg) do defaults[k] = v; end function set_config(settings) local event_settings = { ACCEPT_DELAY = settings.accept_retry_interval; ACCEPT_QUEUE = settings.tcp_backlog; CLEAR_DELAY = settings.event_clear_interval; CONNECT_TIMEOUT = settings.connect_timeout; DEBUG = settings.debug; HANDSHAKE_TIMEOUT = settings.ssl_handshake_timeout; MAX_CONNECTIONS = settings.max_connections; MAX_HANDSHAKE_ATTEMPTS = settings.max_ssl_handshake_roundtrips; MAX_READ_LENGTH = settings.max_receive_buffer_size; MAX_SEND_LENGTH = settings.max_send_buffer_size; READ_TIMEOUT = settings.read_timeout; WRITE_TIMEOUT = settings.send_timeout; }; for k,default in pairs(defaults) do server.cfg[k] = event_settings[k] or default; end end elseif server_type == "select" then -- TODO Remove completely. log("warn", "select is deprecated, the new default is epoll. For more info see https://prosody.im/doc/network_backend"); server = require "prosody.net.server_select"; local defaults = {}; for k,v in pairs(server.getsettings()) do defaults[k] = v; end function set_config(settings) local select_settings = {}; for k,default in pairs(defaults) do select_settings[k] = settings[k] or default; end server.changesettings(select_settings); end else server = require("prosody.net.server_"..server_type); set_config = server.set_config; if not server.get_backend then function server.get_backend() return server_type; end end end -- If server.hook_signal exists, replace signal.signal() local has_signal, signal = pcall(require, "prosody.util.signal"); if has_signal then if server.hook_signal then function signal.signal(signal_id, handler) if type(signal_id) == "string" then signal_id = signal[signal_id:upper()]; end if type(signal_id) ~= "number" then return false, "invalid-signal"; end return server.hook_signal(signal_id, handler); end else server.hook_signal = signal.signal; end else if not server.hook_signal then server.hook_signal = function() return false, "signal hooking not supported" end end end if prosody and set_config then local config_get = require "prosody.core.configmanager".get; local function load_config() local settings = config_get("*", "network_settings") or {}; return set_config(settings); end load_config(); prosody.events.add_handler("config-reloaded", load_config); end if prosody and server.tls_builder then local tls_builder = server.tls_builder; -- resolving the basedir here avoids util.sslconfig depending on -- prosody.paths.config function server.tls_builder() return tls_builder(prosody.paths.config or "") end end -- require "prosody.net.server" shall now forever return this, -- ie. server_select or server_event as chosen above. return server;