This adds support for encrypted ONC import

chrome/browser/chromeos/cros/onc_network_parser.cc

 // Copyright (c) 2011 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.
 
 #include "chrome/browser/chromeos/cros/onc_network_parser.h"
 
 #include <keyhi.h>
 #include <pk11pub.h>
 
 #include "base/base64.h"
 #include "base/json/json_value_serializer.h"
 #include "base/json/json_writer.h"  // for debug output only.
 #include "base/stringprintf.h"
 #include "base/values.h"
 #include "chrome/browser/chromeos/cros/native_network_constants.h"
 #include "chrome/browser/chromeos/cros/native_network_parser.h"
 #include "chrome/browser/chromeos/cros/network_library.h"
 #include "chrome/browser/chromeos/cros/onc_constants.h"
 #include "chrome/common/net/x509_certificate_model.h"
+#include "crypto/encryptor.h"
+#include "crypto/hmac.h"
+#include "crypto/scoped_nss_types.h"
+#include "crypto/symmetric_key.h"
 #include "grit/generated_resources.h"
 #include "net/base/cert_database.h"
 #include "net/base/crypto_module.h"
 #include "net/base/net_errors.h"
 #include "net/base/x509_certificate.h"
 #include "third_party/cros_system_api/dbus/service_constants.h"
 #include "ui/base/l10n/l10n_util.h"
 
 namespace chromeos {
 
@@ skipping 162 matching lines @@
   std::string value_json;
   base::JSONWriter::Write(&value, false, &value_json);
   return value_json;
 }
 
 }  // namespace
 
 // -------------------- OncNetworkParser --------------------
 
 OncNetworkParser::OncNetworkParser(const std::string& onc_blob,
+                                   const std::string& passphrase,
                                    NetworkUIData::ONCSource onc_source)
     : NetworkParser(get_onc_mapper()),
       onc_source_(onc_source),
       network_configs_(NULL),
       certificates_(NULL) {
   VLOG(2) << __func__ << ": OncNetworkParser called on " << onc_blob;
   JSONStringValueSerializer deserializer(onc_blob);
   deserializer.set_allow_trailing_comma(true);
   scoped_ptr<base::Value> root(deserializer.Deserialize(NULL, &parse_error_));
 
   if (!root.get() || root->GetType() != base::Value::TYPE_DICTIONARY) {
     LOG(WARNING) << "OncNetworkParser received bad ONC file: " << parse_error_;
   } else {
     root_dict_.reset(static_cast<DictionaryValue*>(root.release()));
+
+    // Check and see if this is an encrypted ONC file.  If so, decrypt it.
+    std::string ciphertext_test;
+    if (root_dict_->GetString("Ciphertext", &ciphertext_test))
+      root_dict_.reset(Decrypt(passphrase, root_dict_.get()));
+
+    // Decryption failed, errors will be in parse_error_;
+    if (!root_dict_.get())
+      return;
+
     // At least one of NetworkConfigurations or Certificates is required.
     bool has_network_configurations =
-      root_dict_->GetList("NetworkConfigurations", &network_configs_);
+        root_dict_->GetList("NetworkConfigurations", &network_configs_);
     bool has_certificates =
-      root_dict_->GetList("Certificates", &certificates_);
+        root_dict_->GetList("Certificates", &certificates_);
     VLOG(2) << "ONC file has " << GetNetworkConfigsSize() << " networks and "
             << GetCertificatesSize() << " certificates";
     LOG_IF(WARNING, (!has_network_configurations && !has_certificates))
-      << "ONC file has no NetworkConfigurations or Certificates.";
+        << "ONC file has no NetworkConfigurations or Certificates.";
   }
 }
 
 OncNetworkParser::OncNetworkParser()
     : NetworkParser(get_onc_mapper()),
       network_configs_(NULL),
       certificates_(NULL) {
 }
 
 OncNetworkParser::~OncNetworkParser() {
 }
 
 // static
 const EnumMapper<PropertyIndex>* OncNetworkParser::property_mapper() {
   return get_onc_mapper();
 }
 
+base::DictionaryValue* OncNetworkParser::Decrypt(
+    const std::string& passphrase,
+    base::DictionaryValue* root) {
+  const int key_size_in_bits = 256;

[agl, 2012/01/06 15:59:56]

(ignore if you like.) I'd expect a constant to be called kKeySizeInBits, or even
kKeyBits.

[Greg Spencer (Chromium), 2012/01/06 21:45:55]

Done.

+  std::string onc_type;
+  std::string initial_vector_str;
+  std::string salt;
+  std::string cipher;
+  std::string stretch_method;
+  std::string hmac_method;
+  std::string hmac;
+  int iterations;
+  std::string ciphertext;
+
+  if (!root->GetString("Type", &onc_type) ||
+      onc_type != "EncryptedConfiguration" ||
+      !root->GetString("IV", &initial_vector_str) ||
+      !root->GetString("Salt", &salt) ||
+      !root->GetString("Cipher", &cipher) ||
+      !root->GetString("Stretch", &stretch_method) ||
+      !root->GetString("HMACMethod", &hmac_method) ||
+      !root->GetString("HMAC", &hmac) ||
+      !root->GetInteger("Iterations", &iterations) ||
+      !root->GetString("Ciphertext", &ciphertext)) {
+    parse_error_ = l10n_util::GetStringUTF8(
+        IDS_NETWORK_CONFIG_ERROR_ENCRYPTED_ONC_MALFORMED);
+    return NULL;
+  }
+
+  if (hmac_method != "SHA1" ||
+      cipher != "AES256" ||
+      stretch_method != "PBKDF2") {
+    parse_error_ = l10n_util::GetStringUTF8(
+        IDS_NETWORK_CONFIG_ERROR_ENCRYPTED_ONC_UNSUPPORTED_ENCRYPTION);
+    return NULL;
+  }
+
+  if (!base::Base64Decode(salt, &salt)) {
+    parse_error_ = l10n_util::GetStringUTF8(
+        IDS_NETWORK_CONFIG_ERROR_ENCRYPTED_ONC_UNABLE_TO_DECODE);
+    return NULL;
+  }
+
+  scoped_ptr<crypto::SymmetricKey> key(
+      crypto::SymmetricKey::DeriveKeyFromPassword(crypto::SymmetricKey::AES,
+                                                  passphrase,
+                                                  salt,
+                                                  iterations,

[agl, 2012/01/06 15:59:56]

I know that Ryan has already commented on this, but I really would put in a
sanity check on iterations. Even if it's just checking that it's less than a
million.

[Greg Spencer (Chromium), 2012/01/06 21:45:55]

I added a check for values > 500,000.
That should be OK for a number of years, at least, and that will occupy a
current machine for about 20 seconds.

+                                                  key_size_in_bits));
+

[agl, 2012/01/06 15:59:56]

(ignore if you like.) Extra blank line?

[Greg Spencer (Chromium), 2012/01/06 21:45:55]

Removed.

+
+  crypto::Encryptor decryptor;
+  std::string initial_vector;
+  std::string plaintext;
+  if (!base::Base64Decode(initial_vector_str, &initial_vector)) {
+    parse_error_ = l10n_util::GetStringUTF8(
+        IDS_NETWORK_CONFIG_ERROR_ENCRYPTED_ONC_UNABLE_TO_DECODE);
+    return NULL;
+  }
+  if (!base::Base64Decode(ciphertext, &ciphertext)) {
+    parse_error_ = l10n_util::GetStringUTF8(
+        IDS_NETWORK_CONFIG_ERROR_ENCRYPTED_ONC_UNABLE_TO_DECODE);
+    return NULL;
+  }
+  if (!base::Base64Decode(hmac, &hmac)) {
+    parse_error_ = l10n_util::GetStringUTF8(
+        IDS_NETWORK_CONFIG_ERROR_ENCRYPTED_ONC_UNABLE_TO_DECODE);
+    return NULL;
+  }
+
+  if (!decryptor.Init(key.get(), crypto::Encryptor::CBC, initial_vector))  {

[agl, 2012/01/06 15:59:56]

(ignore if you like.) Move decryptor.Init below the HMAC check so that it's just
above decryptor.Decrypt?

[Greg Spencer (Chromium), 2012/01/06 21:45:55]

Done.

+    parse_error_ = l10n_util::GetStringUTF8(
+        IDS_NETWORK_CONFIG_ERROR_ENCRYPTED_ONC_UNABLE_TO_DECRYPT);
+    return NULL;
+  }
+  // Verify the HMAC.  If it fails, then we will still try to decrypt because

[agl, 2012/01/06 15:59:56]

I don't think that you need to worry about the timing here. Timing is an issue
when the encryption wraps the MAC because a failed decryption leaks information
about the validity of the padding.

However, we can assume that the HMAC works - i.e. that the attacker cannot forge
a valid HMAC. At that point, invalid padding can only be caused by a broken
implementation at the generator.

[Greg Spencer (Chromium), 2012/01/06 21:45:55]

OK, I'll fail earlier on a bad HMAC then.

+  // we don't want to leak timing information.
+  bool hmac_failed = false;
+  crypto::HMAC hmac_verifier(crypto::HMAC::SHA1);
+  if (!hmac_verifier.Init(key.get()) || !hmac_verifier.Verify(ciphertext, hmac))
+    hmac_failed = true;
+
+  if (!decryptor.Decrypt(ciphertext, &plaintext) || hmac_failed) {
+    parse_error_ = l10n_util::GetStringUTF8(
+        IDS_NETWORK_CONFIG_ERROR_ENCRYPTED_ONC_UNABLE_TO_DECRYPT);
+    return NULL;
+  }
+
+  // Now we've decrypted it, let's deserialize the decrypted data.
+  JSONStringValueSerializer deserializer(plaintext);
+  deserializer.set_allow_trailing_comma(true);
+  scoped_ptr<base::Value> new_root(deserializer.Deserialize(NULL,
+                                                            &parse_error_));
+  if (!new_root.get() || !new_root->IsType(base::Value::TYPE_DICTIONARY)) {
+    if (parse_error_.empty())
+      parse_error_ = l10n_util::GetStringUTF8(
+          IDS_NETWORK_CONFIG_ERROR_NETWORK_PROP_DICT_MALFORMED);
+    return NULL;
+  }
+  return static_cast<base::DictionaryValue*>(new_root.release());
+}
+
 int OncNetworkParser::GetNetworkConfigsSize() const {
   return network_configs_ ? network_configs_->GetSize() : 0;
 }
 
 const base::DictionaryValue* OncNetworkParser::GetNetworkConfig(int n) {
   CHECK(network_configs_);
   CHECK(static_cast<size_t>(n) < network_configs_->GetSize());
   CHECK_GE(n, 0);
   base::DictionaryValue* info = NULL;
   if (!network_configs_->GetDictionary(n, &info)) {
@@ skipping 1017 matching lines @@
     // on the value of AuthenticationType.
     { "L2TP-IPsec", PROVIDER_TYPE_L2TP_IPSEC_PSK },
     { "OpenVPN", PROVIDER_TYPE_OPEN_VPN },
   };
   CR_DEFINE_STATIC_LOCAL(EnumMapper<ProviderType>, parser,
       (table, arraysize(table), PROVIDER_TYPE_MAX));
   return parser.Get(type);
 }
 
 }  // namespace chromeos