net: allow fallback down to TLS 1.0 in the event of a bad-record-MAC alert.

net/socket/ssl_client_socket_nss.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file includes code SSLClientSocketNSS::DoVerifyCertComplete() derived
 // from AuthCertificateCallback() in
 // mozilla/security/manager/ssl/src/nsNSSCallbacks.cpp.
 
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
@@ skipping 1843 matching lines @@
     // fallback will be more painful for TLS 1.2 when we have GCM support.
     //
     // ERR_CONNECTION_RESET is a common network error, so we don't want it
     // to trigger a version fallback in general, especially the TLS 1.0 ->
     // SSL 3.0 fallback, which would drop TLS extensions.
     if (prerr == PR_CONNECT_RESET_ERROR &&
         ssl_config_.version_max >= SSL_PROTOCOL_VERSION_TLS1_1) {
       net_error = ERR_SSL_PROTOCOL_ERROR;
     }
 
+    // Some broken SSL devices negotiate TLS 1.0 when sent a TLS 1.1 or 1.2
+    // ClientHello, but then return a bad-record-MAC alert. See
+    // crbug.com/260358. In order to make the fallback as minimal as possible,
+    // this fallback is only triggered for >= TLS 1.1.
+    if (net_error == ERR_SSL_BAD_RECORD_MAC_ALERT &&
+        ssl_config_.version_max >= SSL_PROTOCOL_VERSION_TLS1_1) {
+      net_error = ERR_SSL_PROTOCOL_ERROR;
+    }
+
     // If not done, stay in this state
     if (net_error == ERR_IO_PENDING) {
       GotoState(STATE_HANDSHAKE);
     } else {
       PostOrRunCallback(
           FROM_HERE,
           base::Bind(&AddLogEventWithCallback, weak_net_log_,
                      NetLog::TYPE_SSL_HANDSHAKE_ERROR,
                      CreateNetLogSSLErrorCallback(net_error, prerr)));
     }
@@ skipping 1647 matching lines @@
   EnsureThreadIdAssigned();
   base::AutoLock auto_lock(lock_);
   return valid_thread_id_ == base::PlatformThread::CurrentId();
 }
 
 ServerBoundCertService* SSLClientSocketNSS::GetServerBoundCertService() const {
   return server_bound_cert_service_;
 }
 
 }  // namespace net