Modify sigalgs extension processing to accomodate TLS 1.3.

- Make a separate sigalgs list for TLS 1.3 including only modern
algorithm choices which we use when the handshake will not negotiate
TLS 1.2.
- Modify the legacy sigalgs for TLS 1.2 to include the RSA PSS algorithms as
mandated by RFC8446 when the handshake will permit negotiation of TLS 1.2
from a 1.3 handshake.
ok jsing@ tb@

1 files changed, 3 insertions, 2 deletions

diff --git a/src/lib/libssl/ssl_clnt.c b/src/lib/libssl/ssl_clnt.c
index 26755d7c03..e9e900b643 100644
--- a/src/lib/libssl/ssl_clnt.c
+++ b/src/lib/libssl/ssl_clnt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_clnt.c,v 1.54 2019/01/23 18:24:40 beck Exp $ */
+/* $OpenBSD: ssl_clnt.c,v 1.55 2019/01/23 18:39:28 beck Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1680,7 +1680,8 @@ ssl3_get_certificate_request(SSL *s)
                         SSLerror(s, SSL_R_DATA_LENGTH_TOO_LONG);
                         goto err;
                 }
-                if (!tls1_process_sigalgs(s, &sigalgs)) {
+                if (!tls1_process_sigalgs(s, &sigalgs, tls12_sigalgs,
+                    tls12_sigalgs_len)) {
                         ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                         SSLerror(s, SSL_R_SIGNATURE_ALGORITHMS_ERROR);
                         goto err;