Workaround for Windows-based GOST implementations

Many Windows-based GOST TLS implementations are unable to extend the
list of supported SignatureAlgorithms because of lack of the necessary
callback in Windows. So for TLS 1.2 it makes sense to imply the support
of GOST algorithms in case when the GOST ciphersuites are present.

This is a backport of #10377 to 1.1.1 branch

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/10378)

diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index 9a6328449fed6701cdc4daacb9014d170a4ac71b..8498528b716c8a60f11a7fdc82c3b2aafaa5cc36 100644 (file)
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -2774,6 +2774,26 @@ int tls_choose_sigalg(SSL *s, int fatalerrs)
 #endif
                         break;
                 }
+#ifndef OPENSSL_NO_GOST
+                /*
+                 * Some Windows-based implementations do not send GOST algorithms indication
+                 * in supported_algorithms extension, so when we have GOST-based ciphersuite,
+                 * we have to assume GOST support.
+                 */
+                if (i == s->shared_sigalgslen && s->s3->tmp.new_cipher->algorithm_auth & (SSL_aGOST01 | SSL_aGOST12)) {
+                  if ((lu = tls1_get_legacy_sigalg(s, -1)) == NULL) {
+                    if (!fatalerrs)
+                      return 1;
+                    SSLfatal(s, SSL_AD_HANDSHAKE_FAILURE,
+                             SSL_F_TLS_CHOOSE_SIGALG,
+                             SSL_R_NO_SUITABLE_SIGNATURE_ALGORITHM);
+                    return 0;
+                  } else {
+                    i = 0;
+                    sig_idx = lu->sig_idx;
+                  }
+                }
+#endif
                 if (i == s->shared_sigalgslen) {
                     if (!fatalerrs)
                         return 1;