From 574d6f0d7739a1810b9aad1f62716ceadbe58540 Mon Sep 17 00:00:00 2001
From: jsing <>
Date: Fri, 29 May 2020 17:47:30 +0000
Subject: Wire up the servername callback in the TLSv1.3 server.

This makes SNI work correctly with TLSv1.3.

Found the hard way by danj@, gonzalo@ and others.

ok beck@ inoguchi@ tb@
---
 src/lib/libssl/tls13_internal.h |  3 ++-
 src/lib/libssl/tls13_legacy.c   | 28 +++++++++++++++++++++++++++-
 src/lib/libssl/tls13_server.c   | 17 ++++++++++++++++-
 3 files changed, 45 insertions(+), 3 deletions(-)

(limited to 'src/lib')

diff --git a/src/lib/libssl/tls13_internal.h b/src/lib/libssl/tls13_internal.h
index 770c18d6ad..96ed981959 100644
--- a/src/lib/libssl/tls13_internal.h
+++ b/src/lib/libssl/tls13_internal.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls13_internal.h,v 1.82 2020/05/23 11:57:41 jsing Exp $ */
+/* $OpenBSD: tls13_internal.h,v 1.83 2020/05/29 17:47:30 jsing Exp $ */
 /*
  * Copyright (c) 2018 Bob Beck <beck@openbsd.org>
  * Copyright (c) 2018 Theo Buehler <tb@openbsd.org>
@@ -311,6 +311,7 @@ int tls13_legacy_read_bytes(SSL *ssl, int type, unsigned char *buf, int len,
     int peek);
 int tls13_legacy_write_bytes(SSL *ssl, int type, const void *buf, int len);
 int tls13_legacy_shutdown(SSL *ssl);
+int tls13_legacy_servername_process(struct tls13_ctx *ctx, uint8_t *alert);
 
 /*
  * Message Types - RFC 8446, Section B.3.
diff --git a/src/lib/libssl/tls13_legacy.c b/src/lib/libssl/tls13_legacy.c
index be89e9aa24..4d68287141 100644
--- a/src/lib/libssl/tls13_legacy.c
+++ b/src/lib/libssl/tls13_legacy.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tls13_legacy.c,v 1.7 2020/05/16 14:42:35 jsing Exp $ */
+/*	$OpenBSD: tls13_legacy.c,v 1.8 2020/05/29 17:47:30 jsing Exp $ */
 /*
  * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
  *
@@ -519,3 +519,29 @@ tls13_legacy_shutdown(SSL *ssl)
 
 	return 0;
 }
+
+int
+tls13_legacy_servername_process(struct tls13_ctx *ctx, uint8_t *alert)
+{
+	int legacy_alert = SSL_AD_UNRECOGNIZED_NAME;
+	int ret = SSL_TLSEXT_ERR_NOACK;
+	SSL_CTX *ssl_ctx = ctx->ssl->ctx;
+	SSL *ssl = ctx->ssl;
+
+	if (ssl_ctx->internal->tlsext_servername_callback == NULL)
+		ssl_ctx = ssl->initial_ctx;
+	if (ssl_ctx->internal->tlsext_servername_callback == NULL)
+		return 1;
+
+	ret = ssl_ctx->internal->tlsext_servername_callback(ssl, &legacy_alert,
+	    ssl_ctx->internal->tlsext_servername_arg);
+
+	if (ret == SSL_TLSEXT_ERR_ALERT_FATAL ||
+	    ret == SSL_TLSEXT_ERR_ALERT_WARNING) {
+		if (legacy_alert >= 0 && legacy_alert <= 255)
+			*alert = legacy_alert;
+		return 0;
+	}
+
+	return 1;
+}
diff --git a/src/lib/libssl/tls13_server.c b/src/lib/libssl/tls13_server.c
index 621e51d501..181ba583a0 100644
--- a/src/lib/libssl/tls13_server.c
+++ b/src/lib/libssl/tls13_server.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls13_server.c,v 1.53 2020/05/23 11:58:46 jsing Exp $ */
+/* $OpenBSD: tls13_server.c,v 1.54 2020/05/29 17:47:30 jsing Exp $ */
 /*
  * Copyright (c) 2019, 2020 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2020 Bob Beck <beck@openbsd.org>
@@ -373,6 +373,19 @@ tls13_client_hello_retry_recv(struct tls13_ctx *ctx, CBS *cbs)
 	return 1;
 }
 
+static int
+tls13_servername_process(struct tls13_ctx *ctx)
+{
+	uint8_t alert = TLS13_ALERT_INTERNAL_ERROR;
+
+	if (!tls13_legacy_servername_process(ctx, &alert)) {
+		ctx->alert = alert;
+		return 0;
+	}
+
+	return 1;
+}
+
 int
 tls13_server_hello_send(struct tls13_ctx *ctx, CBB *cbb)
 {
@@ -380,6 +393,8 @@ tls13_server_hello_send(struct tls13_ctx *ctx, CBB *cbb)
 		return 0;
 	if (!tls13_key_share_generate(ctx->hs->key_share))
 		return 0;
+	if (!tls13_servername_process(ctx))
+		return 0;
 
 	ctx->hs->server_group = 0;
 
-- 
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