From cc0e5dc34b53f139f9149466ab68ee731915f8c7 Mon Sep 17 00:00:00 2001 From: Kim Alvefur Date: Mon, 23 Nov 2020 21:42:52 +0100 Subject: mod_saslauth: Disable 'tls-unique' channel binding with TLS 1.3 (closes #1542) The 'tls-unique' channel binding is undefined in TLS 1.3 according to a single sentence in parenthesis in Apendix C of RFC 8446 This may trigger downgrade protection in clients that were expecting channel binding to be available. --- plugins/mod_saslauth.lua | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/plugins/mod_saslauth.lua b/plugins/mod_saslauth.lua index fba84ef8..333640fc 100644 --- a/plugins/mod_saslauth.lua +++ b/plugins/mod_saslauth.lua @@ -252,7 +252,10 @@ module:hook("stream-features", function(event) -- FIXME: would be nice to have this check only once and not for every socket if sasl_handler.add_cb_handler then local socket = origin.conn:socket(); - if socket.getpeerfinished then + local info = socket.info and socket:info(); + if info.protocol == "TLSv1.3" then + log("debug", "Channel binding 'tls-unique' undefined in context of TLS 1.3"); + elseif socket.getpeerfinished then sasl_handler:add_cb_handler("tls-unique", tls_unique); end sasl_handler["userdata"] = { -- cgit v1.2.3