TLS: Temporarly downgrade newly generated EVP_PKEYs to legacy

The transfer of TLS encodedpoint to backends isn't yet fully supported
in provider implementations.  This is a temporary measure so as not to
get stuck in other development.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/11358)

1 files changed, 30 insertions, 0 deletions

diff --git a/ssl/statem/extensions_srvr.c b/ssl/statem/extensions_srvr.c
index 549a207430..bafd62a0db 100644
--- a/ssl/statem/extensions_srvr.c
+++ b/ssl/statem/extensions_srvr.c
@@ -711,6 +711,21 @@ int tls_parse_ctos_key_share(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
             return 0;
         }
 
+        /*
+         * TODO(3.0) Remove this when EVP_PKEY_get1_tls_encodedpoint()
+         * knows how to get a key from an encoded point with the help of
+         * a OSSL_SERIALIZER deserializer.  We know that EVP_PKEY_get0()
+         * downgrades an EVP_PKEY to contain a legacy key.
+         *
+         * THIS IS TEMPORARY
+         */
+        EVP_PKEY_get0(s->s3.peer_tmp);
+        if (EVP_PKEY_id(s->s3.peer_tmp) == EVP_PKEY_NONE) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PARSE_CTOS_KEY_SHARE,
+                     ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
+
         s->s3.group_id = group_id;
 
         if (!EVP_PKEY_set1_tls_encodedpoint(s->s3.peer_tmp,
@@ -1736,6 +1751,21 @@ EXT_RETURN tls_construct_stoc_key_share(SSL *s, WPACKET *pkt,
         return EXT_RETURN_FAIL;
     }
 
+    /*
+     * TODO(3.0) Remove this when EVP_PKEY_get1_tls_encodedpoint()
+     * knows how to get a key from an encoded point with the help of
+     * a OSSL_SERIALIZER deserializer.  We know that EVP_PKEY_get0()
+     * downgrades an EVP_PKEY to contain a legacy key.
+     *
+     * THIS IS TEMPORARY
+     */
+    EVP_PKEY_get0(skey);
+    if (EVP_PKEY_id(skey) == EVP_PKEY_NONE) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_STOC_KEY_SHARE,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
     /* Generate encoding of server key */
     encoded_pt_len = EVP_PKEY_get1_tls_encodedpoint(skey, &encodedPoint);
     if (encoded_pt_len == 0) {