diff options
| author | Joel Sing <jsing@cvs.openbsd.org> | 2020-01-25 14:23:28 +0000 |
|---|---|---|
| committer | Joel Sing <jsing@cvs.openbsd.org> | 2020-01-25 14:23:28 +0000 |
| commit | 800ed8df42f692d55a629b2d5a21a3c3779943fa (patch) | |
| tree | bc10603851cf966c7509e6faf6e7cd72efc77ed7 /lib/libssl | |
| parent | 8bcdcc147ac0acbf52ccfd2801628c0a1d4b278a (diff) | |
Only perform the downgrade check if our max version is less than TLSv1.3.
Issue noticed by kn@ when talking to a TLSv1.3 capable mail server, but
with smtpd capping max version to TLSv1.2.
ok beck@
Diffstat (limited to 'lib/libssl')
| -rw-r--r-- | lib/libssl/tls13_client.c | 32 |
1 files changed, 17 insertions, 15 deletions
diff --git a/lib/libssl/tls13_client.c b/lib/libssl/tls13_client.c index 737a1015a56..fb21b54621e 100644 --- a/lib/libssl/tls13_client.c +++ b/lib/libssl/tls13_client.c @@ -1,4 +1,4 @@ -/* $OpenBSD: tls13_client.c,v 1.33 2020/01/25 09:20:56 jsing Exp $ */ +/* $OpenBSD: tls13_client.c,v 1.34 2020/01/25 14:23:27 jsing Exp $ */ /* * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org> * @@ -288,20 +288,22 @@ tls13_server_hello_process(struct tls13_ctx *ctx, CBS *cbs) goto err; if (tls13_server_hello_is_legacy(cbs)) { - /* - * RFC 8446 section 4.1.3, We must not downgrade if - * the server random value contains the TLS 1.2 or 1.1 - * magical value. - */ - if (!CBS_skip(&server_random, CBS_len(&server_random) - - sizeof(tls13_downgrade_12))) - goto err; - if (CBS_mem_equal(&server_random, tls13_downgrade_12, - sizeof(tls13_downgrade_12)) || - CBS_mem_equal(&server_random, tls13_downgrade_11, - sizeof(tls13_downgrade_11))) { - ctx->alert = SSL_AD_ILLEGAL_PARAMETER; - goto err; + if (ctx->hs->max_version >= TLS1_3_VERSION) { + /* + * RFC 8446 section 4.1.3, We must not downgrade if + * the server random value contains the TLS 1.2 or 1.1 + * magical value. + */ + if (!CBS_skip(&server_random, CBS_len(&server_random) - + sizeof(tls13_downgrade_12))) + goto err; + if (CBS_mem_equal(&server_random, tls13_downgrade_12, + sizeof(tls13_downgrade_12)) || + CBS_mem_equal(&server_random, tls13_downgrade_11, + sizeof(tls13_downgrade_11))) { + ctx->alert = SSL_AD_ILLEGAL_PARAMETER; + goto err; + } } if (!CBS_skip(cbs, CBS_len(cbs))) |