Require ECDHE cipher in remoting client.

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 2743 matching lines @@
 
   SSLVersionRange version_range;
   version_range.min = ssl_config_.version_min;
   version_range.max = ssl_config_.version_max;
   rv = SSL_VersionRangeSet(nss_fd_, &version_range);
   if (rv != SECSuccess) {
     LogFailedNSSFunction(net_log_, "SSL_VersionRangeSet", "");
     return ERR_NO_SSL_VERSIONS_ENABLED;
   }
 
+  if (ssl_config_.require_ecdhe) {
+    const PRUint16* const ssl_ciphers = SSL_GetImplementedCiphers();
+    const PRUint16 num_ciphers = SSL_GetNumImplementedCiphers();
+
+    // Require forward security by iterating over the cipher suites and

[davidben, 2015/06/16 19:18:21]

Nit: Maybe just:

  // Iterate over the cipher suites and disable all those that don't use ECDHE.

Since DHE nominally also gets us forward secrecy, but (a) DHE is very sad
because of the group size issue and (b) isn't sufficient for our purposes here
anyway.

[Sergey Ulanov, 2015/06/16 19:29:07]

Done. Also updated the same comment in ssl_server_socket_nss.cc

+    // disabling all those that don't use ECDHE.
+    for (unsigned i = 0; i < num_ciphers; i++) {
+      SSLCipherSuiteInfo info;
+      if (SSL_GetCipherSuiteInfo(ssl_ciphers[i], &info, sizeof(info)) ==
+          SECSuccess) {
+        if (strcmp(info.keaTypeName, "ECDHE") != 0) {
+          SSL_CipherPrefSet(nss_fd_, ssl_ciphers[i], PR_FALSE);
+        }
+      }
+    }
+  }
+
   if (ssl_config_.version_fallback) {
     rv = SSL_OptionSet(nss_fd_, SSL_ENABLE_FALLBACK_SCSV, PR_TRUE);
     if (rv != SECSuccess) {
       LogFailedNSSFunction(
           net_log_, "SSL_OptionSet", "SSL_ENABLE_FALLBACK_SCSV");
     }
   }
 
   for (std::vector<uint16>::const_iterator it =
            ssl_config_.disabled_cipher_suites.begin();
@@ skipping 405 matching lines @@
   return channel_id_service_;
 }
 
 SSLFailureState SSLClientSocketNSS::GetSSLFailureState() const {
   if (completed_handshake_)
     return SSL_FAILURE_NONE;
   return SSL_FAILURE_UNKNOWN;
 }
 
 }  // namespace net