From 677485c9fffaa8a425101295cc5843cac4787811 Mon Sep 17 00:00:00 2001 From: Andrey Rachitskiy Date: Fri, 30 Oct 2026 23:25:27 +0500 Subject: [PATCH] Fix missing alert when ClientHello has no server_name sni_clienthello_cb() requests SSL_AD_MISSING_EXTENSION when the ClientHello has no server_name and pg_hosts.conf has no fallback. OpenSSL runs the callback before choosing a protocol version and translates the alert with tls1_alert_code(). OpenSSL 1.1.1 has no mapping for that alert and closes the socket, so libpq reports "SSL SYSCALL error: EOF detected". OpenSSL 3 rewrites the same alert to handshake_failure, which src/test/ssl/t/004_sni.pl already expects. Request SSL_AD_HANDSHAKE_FAILURE instead. OpenSSL 1.1.1 sends that alert, and the client message on OpenSSL 3 stays the same. Author: Andrey Rachitskiy Reported-by: Ben Mejia Discussion: https://postgr.es/m/19815-8c6d40e717afe5fd@postgresql.org Backpatch-through: 19 --- src/backend/libpq/be-secure-openssl.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/src/backend/libpq/be-secure-openssl.c b/src/backend/libpq/be-secure-openssl.c index fbd4f1173bc..79f3deab30e 100644 --- a/src/backend/libpq/be-secure-openssl.c +++ b/src/backend/libpq/be-secure-openssl.c @@ -2076,17 +2076,15 @@ sni_clienthello_cb(SSL *ssl, int *al, void *arg) else { /* - * Reaching here means that we didn't get a hostname in the TLS - * extension and the server has been configured to not allow any - * connections without a specified hostname. - * - * The error message for a missing server_name should, according - * to RFC 8446, be missing_extension. This isn't entirely ideal - * since the user won't be able to tell which extension the server - * considered missing. Sending unrecognized_name would be a more - * helpful error, but for now we stick to the RFC. + * No server_name extension, and no fallback. RFC 8446 specifies + * missing_extension for this case. This callback runs before + * OpenSSL selects a protocol version, so the alert is translated + * with the TLS 1.2 table. OpenSSL 1.1.1 has no mapping for + * missing_extension and closes the connection without an alert. + * OpenSSL 3 rewrites it to handshake_failure. Send + * handshake_failure so both versions send an alert. */ - *al = SSL_AD_MISSING_EXTENSION; + *al = SSL_AD_HANDSHAKE_FAILURE; ereport(COMMERROR, (errcode(ERRCODE_PROTOCOL_VIOLATION), @@ -2104,7 +2102,7 @@ sni_clienthello_cb(SSL *ssl, int *al, void *arg) if (tlsext_hostname) *al = SSL_AD_UNRECOGNIZED_NAME; else - *al = SSL_AD_MISSING_EXTENSION; + *al = SSL_AD_HANDSHAKE_FAILURE; return SSL_CLIENT_HELLO_ERROR; } -- 2.53.0