diff options
| author |   beck <beck@openbsd.org> | 2020-01-23 07:30:55 +0000 |
|---|---|---|
| committer | beck <beck@openbsd.org> | 2020-01-23 07:30:55 +0000 |
| commit | 709e85ff7aac016d54db6ea4e81f77a9ba741d54 (patch) | |
| tree | 067a358f840e0010c61c82baaa7c3b1f779bf6bb /lib/libssl/tls13_client.c | |
| parent | do not Xr both pppx and pppac in SEE ALSO, since they are the same page; (diff) | |
| download | wireguard-openbsd-709e85ff7aac016d54db6ea4e81f77a9ba741d54.tar.xz wireguard-openbsd-709e85ff7aac016d54db6ea4e81f77a9ba741d54.zip | |
Add checking int the client to check the magic values which are
set by a 1.3 server when it downgrades to tls 1.2 or 1.1 as per
RFC 8446 section 4.1.3
ok jsing@
Diffstat (limited to 'lib/libssl/tls13_client.c')
| -rw-r--r-- | lib/libssl/tls13_client.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/lib/libssl/tls13_client.c b/lib/libssl/tls13_client.c index cab113b8c32..477cca2e04f 100644 --- a/lib/libssl/tls13_client.c +++ b/lib/libssl/tls13_client.c @@ -1,4 +1,4 @@ -/* $OpenBSD: tls13_client.c,v 1.30 2020/01/23 06:15:44 beck Exp $ */ +/* $OpenBSD: tls13_client.c,v 1.31 2020/01/23 07:30:55 beck Exp $ */ /* * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org> * @@ -285,6 +285,22 @@ 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 (!CBS_skip(cbs, CBS_len(cbs))) goto err; return tls13_use_legacy_client(ctx); |