From 6b9adcf89cc2130fb9b26ac8e68e18a16ae477b7 Mon Sep 17 00:00:00 2001 From: jsing <> Date: Sat, 25 Jan 2020 09:20:56 +0000 Subject: It is possible to receive a pre-TLSv1.3 alert in response to a TLSv1.3 client hello. Allow pre-TLSv1.3 alerts (including warnings) to be received before the server hello message. Disallow pre-TLSv1.3 alerts as soon as we know that we are using TLSv1.3. Noticed by ajacoutot@ while connecting to www.openprinting.org. ok tb@ --- src/lib/libssl/tls13_client.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'src/lib/libssl/tls13_client.c') diff --git a/src/lib/libssl/tls13_client.c b/src/lib/libssl/tls13_client.c index 20b3038b93..737a1015a5 100644 --- a/src/lib/libssl/tls13_client.c +++ b/src/lib/libssl/tls13_client.c @@ -1,4 +1,4 @@ -/* $OpenBSD: tls13_client.c,v 1.32 2020/01/23 11:06:59 beck Exp $ */ +/* $OpenBSD: tls13_client.c,v 1.33 2020/01/25 09:20:56 jsing Exp $ */ /* * Copyright (c) 2018, 2019 Joel Sing * @@ -209,6 +209,9 @@ tls13_client_hello_send(struct tls13_ctx *ctx, CBB *cbb) if (ctx->hs->min_version < TLS1_2_VERSION) tls13_record_layer_set_legacy_version(ctx->rl, TLS1_VERSION); + /* We may receive a pre-TLSv1.3 alert in response to the client hello. */ + tls13_record_layer_allow_legacy_alerts(ctx->rl, 1); + if (!tls13_client_hello_build(ctx, cbb)) return 0; @@ -306,6 +309,9 @@ tls13_server_hello_process(struct tls13_ctx *ctx, CBS *cbs) return tls13_use_legacy_client(ctx); } + /* From here on in we know we are doing TLSv1.3. */ + tls13_record_layer_allow_legacy_alerts(ctx->rl, 0); + if (!tlsext_client_parse(s, cbs, &alert_desc, SSL_TLSEXT_MSG_SH)) { ctx->alert = alert_desc; goto err; -- cgit v1.2.3-55-g6feb