From 18db016c2f067c9886845b7fa9614f0653eb4103 Mon Sep 17 00:00:00 2001 From: Matthew Wild Date: Thu, 26 Oct 2023 15:14:39 +0100 Subject: mod_saslauth, mod_c2s: Disable tls-server-end-point channel binding by default This channel binding method is now enabled when a hash is manually set in the config, or it attempts to discover the hash automatically if the value is the special string "auto". A related change to mod_c2s prevents complicated certificate lookups in the client connection hot path - this work now happens only when this channel binding method is used. I'm not aware of anything else that uses ssl_cfg (vs ssl_ctx). Rationale for disabling by default: - Minor performance impact in automatic cert detection - This method is weak against a leaked/stolen private key (other methods such as 'tls-exporter' would not be compromised in such a case) Rationale for keeping the implementation: - For some deployments, this may be the only method available (e.g. due to TLS offloading in another process/server). --- plugins/mod_saslauth.lua | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-) (limited to 'plugins/mod_saslauth.lua') diff --git a/plugins/mod_saslauth.lua b/plugins/mod_saslauth.lua index 4c0a5c1c..4a5b744d 100644 --- a/plugins/mod_saslauth.lua +++ b/plugins/mod_saslauth.lua @@ -19,6 +19,8 @@ local pem2der = require"util.x509".pem2der; local hashes = require"util.hashes"; local ssl = require "ssl"; -- FIXME Isolate LuaSec from the rest of the code +local certmanager = require "core.certmanager"; +local pm_get_tls_config_at = require "prosody.core.portmanager".get_tls_config_at; local usermanager_get_sasl_handler = require "prosody.core.usermanager".get_sasl_handler; local secure_auth_only = module:get_option_boolean("c2s_require_encryption", module:get_option_boolean("require_encryption", true)); @@ -330,17 +332,31 @@ module:hook("stream-features", function(event) else log("debug", "Channel binding 'tls-unique' not supported (by LuaSec?)"); end - local certfile = origin.ssl_cfg and origin.ssl_cfg.certificate; - -- FIXME .ssl_cfg is set by mod_tls and thus only available with starttls - if tls_server_end_point_hash then + + local certfile; + if tls_server_end_point_hash == "auto" then + local ssl_cfg = origin.ssl_cfg; + if not ssl_cfg then + local server = origin.conn:server(); + local tls_config = pm_get_tls_config_at(server:ip(), server:serverport()); + local autocert = certmanager.find_host_cert(origin.conn:socket():getsniname()); + ssl_cfg = autocert or tls_config; + end + + certfile = ssl_cfg and ssl_cfg.certificate; + if certfile then + log("debug", "Channel binding 'tls-server-end-point' can be offered based on the certificate used"); + sasl_handler:add_cb_handler("tls-server-end-point", tls_server_end_point); + channel_bindings:add("tls-server-end-point"); + else + log("debug", "Channel binding 'tls-server-end-point' set to 'auto' but cannot determine cert"); + end + elseif tls_server_end_point_hash then log("debug", "Channel binding 'tls-server-end-point' can be offered with the configured certificate hash"); sasl_handler:add_cb_handler("tls-server-end-point", tls_server_end_point); channel_bindings:add("tls-server-end-point"); - elseif certfile then - log("debug", "Channel binding 'tls-server-end-point' can be offered based on the certificate used"); - sasl_handler:add_cb_handler("tls-server-end-point", tls_server_end_point); - channel_bindings:add("tls-server-end-point"); end + sasl_handler["userdata"] = { ["tls-unique"] = origin.conn; ["tls-exporter"] = origin.conn; -- cgit v1.2.3