Do not use GOST sig algs in TLSv1.3 where possible
Fixes
@@ -1519,9 +1519,50 @@ static int tls12_sigalg_allowed(SSL *s, int op, const SIGALG_LOOKUP *lu)
|| lu->hash_idx == SSL_MD_MD5_IDX
|| lu->hash_idx == SSL_MD_SHA224_IDX))
return 0;
+
/* See if public key algorithm allowed */
if (ssl_cert_is_disabled(lu->sig_idx))
return 0;
+
+ if (lu->sig == NID_id_GostR3410_2012_256
+ || lu->sig == NID_id_GostR3410_2012_512
+ || lu->sig == NID_id_GostR3410_2001) {
+ /* We never allow GOST sig algs on the server with TLSv1.3 */
+ if (s->server && SSL_IS_TLS13(s))
+ return 0;
+ if (!s->server
+ && s->method->version == TLS_ANY_VERSION
+ && s->s3->tmp.max_ver >= TLS1_3_VERSION) {
+ int i, num;
+ STACK_OF(SSL_CIPHER) *sk;
+
+ /*
+ * We're a client that could negotiate TLSv1.3. We only allow GOST
+ * sig algs if we could negotiate TLSv1.2 or below and we have GOST
+ * ciphersuites enabled.
+ */
+
+ if (s->s3->tmp.min_ver >= TLS1_3_VERSION)
+ return 0;
+
+ sk = SSL_get_ciphers(s);
+ num = sk != NULL ? sk_SSL_CIPHER_num(sk) : 0;
+ for (i = 0; i < num; i++) {
+ const SSL_CIPHER *c;
+
+ c = sk_SSL_CIPHER_value(sk, i);
+ /* Skip disabled ciphers */
+ if (ssl_cipher_disabled(s, c, SSL_SECOP_CIPHER_SUPPORTED, 0))
+ continue;
+
+ if ((c->algorithm_mkey & SSL_kGOST) != 0)
+ break;
+ }
+ if (i == num)
+ return 0;
+ }
+ }
+
if (lu->hash == NID_undef)
return 1;
/* Security bits: half digest bits */
