vtls: refuse setting any SSL version

... previously they were supported if a TLS library would (unexpectedly)
still support them, but from this change they will be refused already in
curl_easy_setopt(). SSLv2 and SSLv3 have been known to be insecure for
many years now.

Closes #6773

8 files changed, 25 insertions, 147 deletions

diff --git a/docs/libcurl/opts/CURLOPT_SSLVERSION.3 b/docs/libcurl/opts/CURLOPT_SSLVERSION.3
index 8cfcdbe7f..2841c160b 100644
--- a/docs/libcurl/opts/CURLOPT_SSLVERSION.3
+++ b/docs/libcurl/opts/CURLOPT_SSLVERSION.3
@@ -5,7 +5,7 @@
 .\" *                            | (__| |_| |  _ <| |___
 .\" *                             \___|\___/|_| \_\_____|
 .\" *
-.\" * Copyright (C) 1998 - 2019, 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
 .\" *
 .\" * This software is licensed as described in the file COPYING, which
 .\" * you should have received as part of this distribution. The terms
@@ -43,9 +43,9 @@ default TLS v1.0 since 7.39.0 (unless the TLS library has a stricter rule).
 .IP CURL_SSLVERSION_TLSv1
 TLS v1.0 or later
 .IP CURL_SSLVERSION_SSLv2
-SSL v2 (but not SSLv3)
+SSL v2 - refused
 .IP CURL_SSLVERSION_SSLv3
-SSL v3 (but not SSLv2)
+SSL v3 - refused
 .IP CURL_SSLVERSION_TLSv1_0
 TLS v1.0 or later (Added in 7.34.0)
 .IP CURL_SSLVERSION_TLSv1_1
@@ -102,6 +102,8 @@ if(curl) {
 }
 .fi
 .SH AVAILABILITY
+SSLv2 and SSLv3 are refused completely since curl 7.77.0
+
 SSLv2 is disabled by default since 7.18.1. Other SSL versions availability may
 vary depending on which backend libcurl has been built to use.
 
diff --git a/lib/setopt.c b/lib/setopt.c
index 5944482a8..53b30da35 100644
--- a/lib/setopt.c
+++ b/lib/setopt.c
@@ -426,6 +426,8 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list param)
       version_max = C_SSLVERSION_MAX_VALUE(arg);
 
       if(version < CURL_SSLVERSION_DEFAULT ||
+         version == CURL_SSLVERSION_SSLv2 ||
+         version == CURL_SSLVERSION_SSLv3 ||
          version >= CURL_SSLVERSION_LAST ||
          version_max < CURL_SSLVERSION_MAX_NONE ||
          version_max >= CURL_SSLVERSION_MAX_LAST)
diff --git a/lib/vtls/mbedtls.c b/lib/vtls/mbedtls.c
index 4b36f2d20..d4504a61f 100644
--- a/lib/vtls/mbedtls.c
+++ b/lib/vtls/mbedtls.c
@@ -263,10 +263,10 @@ mbed_connect_step1(struct Curl_easy *data, struct connectdata *conn,
   char errorbuf[128];
   errorbuf[0] = 0;
 
-  /* mbedTLS only supports SSLv3 and TLSv1 */
-  if(SSL_CONN_CONFIG(version) == CURL_SSLVERSION_SSLv2) {
-    failf(data, "mbedTLS does not support SSLv2");
-    return CURLE_SSL_CONNECT_ERROR;
+  if((SSL_CONN_CONFIG(version) == CURL_SSLVERSION_SSLv2) ||
+     (SSL_CONN_CONFIG(version) == CURL_SSLVERSION_SSLv3)) {
+    failf(data, "Not supported SSL version");
+    return CURLE_NOT_BUILT_IN;
   }
 
 #ifdef THREADING_SUPPORT
@@ -414,13 +414,6 @@ mbed_connect_step1(struct Curl_easy *data, struct connectdata *conn,
                                  MBEDTLS_SSL_MINOR_VERSION_1);
     infof(data, "mbedTLS: Set min SSL version to TLS 1.0\n");
     break;
-  case CURL_SSLVERSION_SSLv3:
-    mbedtls_ssl_conf_min_version(&backend->config, MBEDTLS_SSL_MAJOR_VERSION_3,
-                                 MBEDTLS_SSL_MINOR_VERSION_0);
-    mbedtls_ssl_conf_max_version(&backend->config, MBEDTLS_SSL_MAJOR_VERSION_3,
-                                 MBEDTLS_SSL_MINOR_VERSION_0);
-    infof(data, "mbedTLS: Set SSL version to SSLv3\n");
-    break;
   case CURL_SSLVERSION_TLSv1_0:
   case CURL_SSLVERSION_TLSv1_1:
   case CURL_SSLVERSION_TLSv1_2:
diff --git a/lib/vtls/nss.c b/lib/vtls/nss.c
index a9f6959e3..9be3979c0 100644
--- a/lib/vtls/nss.c
+++ b/lib/vtls/nss.c
@@ -1699,8 +1699,7 @@ static CURLcode nss_sslver_from_curl(PRUint16 *nssver, long version)
     return CURLE_OK;
 
   case CURL_SSLVERSION_SSLv3:
-    *nssver = SSL_LIBRARY_VERSION_3_0;
-    return CURLE_OK;
+    return CURLE_NOT_BUILT_IN;
 
   case CURL_SSLVERSION_TLSv1_0:
     *nssver = SSL_LIBRARY_VERSION_TLS_1_0;
diff --git a/lib/vtls/openssl.c b/lib/vtls/openssl.c
index 6583300b3..88380563f 100644
--- a/lib/vtls/openssl.c
+++ b/lib/vtls/openssl.c
@@ -122,12 +122,6 @@
 #define HAVE_ERR_REMOVE_THREAD_STATE 1
 #endif
 
-#if !defined(HAVE_SSLV2_CLIENT_METHOD) || \
-  OPENSSL_VERSION_NUMBER >= 0x10100000L /* 1.1.0+ has no SSLv2 */
-#undef OPENSSL_NO_SSL2 /* undef first to avoid compiler warnings */
-#define OPENSSL_NO_SSL2
-#endif
-
 #if (OPENSSL_VERSION_NUMBER >= 0x10100000L) && /* OpenSSL 1.1.0+ */ \
     !(defined(LIBRESSL_VERSION_NUMBER) && \
       LIBRESSL_VERSION_NUMBER < 0x20700000L)
@@ -2581,31 +2575,11 @@ static CURLcode ossl_connect_step1(struct Curl_easy *data,
     use_sni(TRUE);
     break;
   case CURL_SSLVERSION_SSLv2:
-#ifdef OPENSSL_NO_SSL2
-    failf(data, OSSL_PACKAGE " was built without SSLv2 support");
+    failf(data, "No SSLv2 support");
     return CURLE_NOT_BUILT_IN;
-#else
-#ifdef USE_OPENSSL_SRP
-    if(ssl_authtype == CURL_TLSAUTH_SRP)
-      return CURLE_SSL_CONNECT_ERROR;
-#endif
-    req_method = SSLv2_client_method();
-    use_sni(FALSE);
-    break;
-#endif
   case CURL_SSLVERSION_SSLv3:
-#ifdef OPENSSL_NO_SSL3_METHOD
-    failf(data, OSSL_PACKAGE " was built without SSLv3 support");
+    failf(data, "No SSLv3 support");
     return CURLE_NOT_BUILT_IN;
-#else
-#ifdef USE_OPENSSL_SRP
-    if(ssl_authtype == CURL_TLSAUTH_SRP)
-      return CURLE_SSL_CONNECT_ERROR;
-#endif
-    req_method = SSLv3_client_method();
-    use_sni(FALSE);
-    break;
-#endif
   default:
     failf(data, "Unrecognized parameter passed via CURLOPT_SSLVERSION");
     return CURLE_SSL_CONNECT_ERROR;
@@ -2693,41 +2667,9 @@ static CURLcode ossl_connect_step1(struct Curl_easy *data,
 #endif
 
   switch(ssl_version) {
-    /* "--sslv2" option means SSLv2 only, disable all others */
     case CURL_SSLVERSION_SSLv2:
-#if OPENSSL_VERSION_NUMBER >= 0x10100000L /* 1.1.0 */
-      SSL_CTX_set_min_proto_version(backend->ctx, SSL2_VERSION);
-      SSL_CTX_set_max_proto_version(backend->ctx, SSL2_VERSION);
-#else
-      ctx_options |= SSL_OP_NO_SSLv3;
-      ctx_options |= SSL_OP_NO_TLSv1;
-#  if OPENSSL_VERSION_NUMBER >= 0x1000100FL
-      ctx_options |= SSL_OP_NO_TLSv1_1;
-      ctx_options |= SSL_OP_NO_TLSv1_2;
-#    ifdef TLS1_3_VERSION
-      ctx_options |= SSL_OP_NO_TLSv1_3;
-#    endif
-#  endif
-#endif
-      break;
-
-    /* "--sslv3" option means SSLv3 only, disable all others */
     case CURL_SSLVERSION_SSLv3:
-#if OPENSSL_VERSION_NUMBER >= 0x10100000L /* 1.1.0 */
-      SSL_CTX_set_min_proto_version(backend->ctx, SSL3_VERSION);
-      SSL_CTX_set_max_proto_version(backend->ctx, SSL3_VERSION);
-#else
-      ctx_options |= SSL_OP_NO_SSLv2;
-      ctx_options |= SSL_OP_NO_TLSv1;
-#  if OPENSSL_VERSION_NUMBER >= 0x1000100FL
-      ctx_options |= SSL_OP_NO_TLSv1_1;
-      ctx_options |= SSL_OP_NO_TLSv1_2;
-#    ifdef TLS1_3_VERSION
-      ctx_options |= SSL_OP_NO_TLSv1_3;
-#    endif
-#  endif
-#endif
-      break;
+      return CURLE_NOT_BUILT_IN;
 
     /* "--tlsv<x.y>" options mean TLS >= version <x.y> */
     case CURL_SSLVERSION_DEFAULT:
diff --git a/lib/vtls/schannel.c b/lib/vtls/schannel.c
index 961a71f6d..7043da3d6 100644
--- a/lib/vtls/schannel.c
+++ b/lib/vtls/schannel.c
@@ -572,11 +572,9 @@ schannel_connect_step1(struct Curl_easy *data, struct connectdata *conn,
       break;
     }
     case CURL_SSLVERSION_SSLv3:
-      schannel_cred.grbitEnabledProtocols = SP_PROT_SSL3_CLIENT;
-      break;
     case CURL_SSLVERSION_SSLv2:
-      schannel_cred.grbitEnabledProtocols = SP_PROT_SSL2_CLIENT;
-      break;
+      failf(data, "SSL versions not supported");
+      return CURLE_NOT_BUILT_IN;
     default:
       failf(data, "Unrecognized parameter passed via CURLOPT_SSLVERSION");
       return CURLE_SSL_CONNECT_ERROR;
diff --git a/lib/vtls/sectransp.c b/lib/vtls/sectransp.c
index 9d637da2e..e32fcb54f 100644
--- a/lib/vtls/sectransp.c
+++ b/lib/vtls/sectransp.c
@@ -1486,21 +1486,9 @@ static CURLcode sectransp_connect_step1(struct Curl_easy *data,
         break;
       }
     case CURL_SSLVERSION_SSLv3:
-      err = SSLSetProtocolVersionMin(backend->ssl_ctx, kSSLProtocol3);
-      if(err != noErr) {
-        failf(data, "Your version of the OS does not support SSLv3");
-        return CURLE_SSL_CONNECT_ERROR;
-      }
-      (void)SSLSetProtocolVersionMax(backend->ssl_ctx, kSSLProtocol3);
-      break;
     case CURL_SSLVERSION_SSLv2:
-      err = SSLSetProtocolVersionMin(backend->ssl_ctx, kSSLProtocol2);
-      if(err != noErr) {
-        failf(data, "Your version of the OS does not support SSLv2");
-        return CURLE_SSL_CONNECT_ERROR;
-      }
-      (void)SSLSetProtocolVersionMax(backend->ssl_ctx, kSSLProtocol2);
-      break;
+      failf(data, "SSL versions not supported");
+      return CURLE_NOT_BUILT_IN;
     default:
       failf(data, "Unrecognized parameter passed via CURLOPT_SSLVERSION");
       return CURLE_SSL_CONNECT_ERROR;
@@ -1535,23 +1523,9 @@ static CURLcode sectransp_connect_step1(struct Curl_easy *data,
         break;
       }
     case CURL_SSLVERSION_SSLv3:
-      err = SSLSetProtocolVersionEnabled(backend->ssl_ctx,
-                                         kSSLProtocol3,
-                                         true);
-      if(err != noErr) {
-        failf(data, "Your version of the OS does not support SSLv3");
-        return CURLE_SSL_CONNECT_ERROR;
-      }
-      break;
     case CURL_SSLVERSION_SSLv2:
-      err = SSLSetProtocolVersionEnabled(backend->ssl_ctx,
-                                         kSSLProtocol2,
-                                         true);
-      if(err != noErr) {
-        failf(data, "Your version of the OS does not support SSLv2");
-        return CURLE_SSL_CONNECT_ERROR;
-      }
-      break;
+      failf(data, "SSL versions not supported");
+      return CURLE_NOT_BUILT_IN;
     default:
       failf(data, "Unrecognized parameter passed via CURLOPT_SSLVERSION");
       return CURLE_SSL_CONNECT_ERROR;
@@ -1583,23 +1557,9 @@ static CURLcode sectransp_connect_step1(struct Curl_easy *data,
     failf(data, "Your version of the OS does not support TLSv1.3");
     return CURLE_SSL_CONNECT_ERROR;
   case CURL_SSLVERSION_SSLv2:
-    err = SSLSetProtocolVersionEnabled(backend->ssl_ctx,
-                                       kSSLProtocol2,
-                                       true);
-    if(err != noErr) {
-      failf(data, "Your version of the OS does not support SSLv2");
-      return CURLE_SSL_CONNECT_ERROR;
-    }
-    break;
   case CURL_SSLVERSION_SSLv3:
-    err = SSLSetProtocolVersionEnabled(backend->ssl_ctx,
-                                       kSSLProtocol3,
-                                       true);
-    if(err != noErr) {
-      failf(data, "Your version of the OS does not support SSLv3");
-      return CURLE_SSL_CONNECT_ERROR;
-    }
-    break;
+    failf(data, "SSL versions not supported");
+    return CURLE_NOT_BUILT_IN;
   default:
     failf(data, "Unrecognized parameter passed via CURLOPT_SSLVERSION");
     return CURLE_SSL_CONNECT_ERROR;
diff --git a/lib/vtls/wolfssl.c b/lib/vtls/wolfssl.c
index c6f428034..21f36504f 100644
--- a/lib/vtls/wolfssl.c
+++ b/lib/vtls/wolfssl.c
@@ -47,16 +47,6 @@
 #endif
 #endif
 
-/* WOLFSSL_ALLOW_SSLV3 is wolfSSL's build time symbol for enabling SSLv3 in
-   options.h, but is only seen in >= 3.6.6 since that's when they started
-   disabling SSLv3 by default. */
-#ifndef WOLFSSL_ALLOW_SSLV3
-#if (LIBWOLFSSL_VERSION_HEX < 0x03006006) || \
-  defined(HAVE_WOLFSSLV3_CLIENT_METHOD)
-#define WOLFSSL_ALLOW_SSLV3
-#endif
-#endif
-
 #include <limits.h>
 
 #include "urldata.h"
@@ -285,18 +275,10 @@ wolfssl_connect_step1(struct Curl_easy *data, struct connectdata *conn,
     failf(data, "wolfSSL: TLS 1.3 is not yet supported");
     return CURLE_SSL_CONNECT_ERROR;
 #endif
+  case CURL_SSLVERSION_SSLv2:
   case CURL_SSLVERSION_SSLv3:
-#ifdef WOLFSSL_ALLOW_SSLV3
-    req_method = SSLv3_client_method();
-    use_sni(FALSE);
-#else
-    failf(data, "wolfSSL does not support SSLv3");
+    failf(data, "SSL versions not supported");
     return CURLE_NOT_BUILT_IN;
-#endif
-    break;
-  case CURL_SSLVERSION_SSLv2:
-    failf(data, "wolfSSL does not support SSLv2");
-    return CURLE_SSL_CONNECT_ERROR;
   default:
     failf(data, "Unrecognized parameter passed via CURLOPT_SSLVERSION");
     return CURLE_SSL_CONNECT_ERROR;