root/chromeos/network/onc/onc_utils.cc

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DEFINITIONS

This source file includes following definitions.
  1. ReadDictionaryFromJson
  2. Decrypt
  3. GetSourceAsString
  4. ExpandField
  5. ExpandStringsInOncObject
  6. ExpandStringsInNetworks
  7. Mask
  8. MapField
  9. MaskCredentialsInOncObject
  10. DecodePEM
  11. GetServerAndCACertsByGUID
  12. ParseAndValidateOncForImport
  13. DecodePEMCertificate
  14. GUIDRefToPEMEncoding
  15. ResolveSingleCertRef
  16. ResolveCertRefList
  17. ResolveSingleCertRefToList
  18. ResolveCertRefsOrRefToList
  19. ResolveServerCertRefsInObject
  20. ResolveServerCertRefsInNetworks
  21. ResolveServerCertRefsInNetwork

// 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.

#include "chromeos/network/onc/onc_utils.h"

#include "base/base64.h"
#include "base/json/json_reader.h"
#include "base/logging.h"
#include "base/metrics/histogram.h"
#include "base/strings/string_util.h"
#include "base/values.h"
#include "chromeos/network/network_event_log.h"
#include "chromeos/network/onc/onc_mapper.h"
#include "chromeos/network/onc/onc_signature.h"
#include "chromeos/network/onc/onc_utils.h"
#include "chromeos/network/onc/onc_validator.h"
#include "crypto/encryptor.h"
#include "crypto/hmac.h"
#include "crypto/symmetric_key.h"
#include "net/cert/pem_tokenizer.h"
#include "net/cert/x509_certificate.h"

#define ONC_LOG_WARNING(message) NET_LOG_WARNING("ONC", message)
#define ONC_LOG_ERROR(message) NET_LOG_ERROR("ONC", message)

using namespace ::onc;

namespace chromeos {
namespace onc {

namespace {

const char kUnableToDecrypt[] = "Unable to decrypt encrypted ONC";
const char kUnableToDecode[] = "Unable to decode encrypted ONC";

}  // namespace

const char kEmptyUnencryptedConfiguration[] =
    "{\"Type\":\"UnencryptedConfiguration\",\"NetworkConfigurations\":[],"
    "\"Certificates\":[]}";

scoped_ptr<base::DictionaryValue> ReadDictionaryFromJson(
    const std::string& json) {
  std::string error;
  base::Value* root = base::JSONReader::ReadAndReturnError(
      json, base::JSON_ALLOW_TRAILING_COMMAS, NULL, &error);

  base::DictionaryValue* dict_ptr = NULL;
  if (!root || !root->GetAsDictionary(&dict_ptr)) {
    ONC_LOG_ERROR("Invalid JSON Dictionary: " + error);
    delete root;
  }

  return make_scoped_ptr(dict_ptr);
}

scoped_ptr<base::DictionaryValue> Decrypt(const std::string& passphrase,
                                          const base::DictionaryValue& root) {
  const int kKeySizeInBits = 256;
  const int kMaxIterationCount = 500000;
  std::string onc_type;
  std::string initial_vector;
  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(encrypted::kCiphertext, &ciphertext) ||
      !root.GetString(encrypted::kCipher, &cipher) ||
      !root.GetString(encrypted::kHMAC, &hmac) ||
      !root.GetString(encrypted::kHMACMethod, &hmac_method) ||
      !root.GetString(encrypted::kIV, &initial_vector) ||
      !root.GetInteger(encrypted::kIterations, &iterations) ||
      !root.GetString(encrypted::kSalt, &salt) ||
      !root.GetString(encrypted::kStretch, &stretch_method) ||
      !root.GetString(toplevel_config::kType, &onc_type) ||
      onc_type != toplevel_config::kEncryptedConfiguration) {

    ONC_LOG_ERROR("Encrypted ONC malformed.");
    return scoped_ptr<base::DictionaryValue>();
  }

  if (hmac_method != encrypted::kSHA1 ||
      cipher != encrypted::kAES256 ||
      stretch_method != encrypted::kPBKDF2) {
    ONC_LOG_ERROR("Encrypted ONC unsupported encryption scheme.");
    return scoped_ptr<base::DictionaryValue>();
  }

  // Make sure iterations != 0, since that's not valid.
  if (iterations == 0) {
    ONC_LOG_ERROR(kUnableToDecrypt);
    return scoped_ptr<base::DictionaryValue>();
  }

  // Simply a sanity check to make sure we can't lock up the machine
  // for too long with a huge number (or a negative number).
  if (iterations < 0 || iterations > kMaxIterationCount) {
    ONC_LOG_ERROR("Too many iterations in encrypted ONC");
    return scoped_ptr<base::DictionaryValue>();
  }

  if (!base::Base64Decode(salt, &salt)) {
    ONC_LOG_ERROR(kUnableToDecode);
    return scoped_ptr<base::DictionaryValue>();
  }

  scoped_ptr<crypto::SymmetricKey> key(
      crypto::SymmetricKey::DeriveKeyFromPassword(crypto::SymmetricKey::AES,
                                                  passphrase,
                                                  salt,
                                                  iterations,
                                                  kKeySizeInBits));

  if (!base::Base64Decode(initial_vector, &initial_vector)) {
    ONC_LOG_ERROR(kUnableToDecode);
    return scoped_ptr<base::DictionaryValue>();
  }
  if (!base::Base64Decode(ciphertext, &ciphertext)) {
    ONC_LOG_ERROR(kUnableToDecode);
    return scoped_ptr<base::DictionaryValue>();
  }
  if (!base::Base64Decode(hmac, &hmac)) {
    ONC_LOG_ERROR(kUnableToDecode);
    return scoped_ptr<base::DictionaryValue>();
  }

  crypto::HMAC hmac_verifier(crypto::HMAC::SHA1);
  if (!hmac_verifier.Init(key.get()) ||
      !hmac_verifier.Verify(ciphertext, hmac)) {
    ONC_LOG_ERROR(kUnableToDecrypt);
    return scoped_ptr<base::DictionaryValue>();
  }

  crypto::Encryptor decryptor;
  if (!decryptor.Init(key.get(), crypto::Encryptor::CBC, initial_vector))  {
    ONC_LOG_ERROR(kUnableToDecrypt);
    return scoped_ptr<base::DictionaryValue>();
  }

  std::string plaintext;
  if (!decryptor.Decrypt(ciphertext, &plaintext)) {
    ONC_LOG_ERROR(kUnableToDecrypt);
    return scoped_ptr<base::DictionaryValue>();
  }

  scoped_ptr<base::DictionaryValue> new_root =
      ReadDictionaryFromJson(plaintext);
  if (new_root.get() == NULL) {
    ONC_LOG_ERROR("Property dictionary malformed.");
    return scoped_ptr<base::DictionaryValue>();
  }

  return new_root.Pass();
}

std::string GetSourceAsString(ONCSource source) {
  switch (source) {
    case ONC_SOURCE_DEVICE_POLICY:
      return "device policy";
    case ONC_SOURCE_USER_POLICY:
      return "user policy";
    case ONC_SOURCE_NONE:
      return "none";
    case ONC_SOURCE_USER_IMPORT:
      return "user import";
  }
  NOTREACHED() << "unknown ONC source " << source;
  return "unknown";
}

void ExpandField(const std::string& fieldname,
                 const StringSubstitution& substitution,
                 base::DictionaryValue* onc_object) {
  std::string user_string;
  if (!onc_object->GetStringWithoutPathExpansion(fieldname, &user_string))
    return;

  std::string login_id;
  if (substitution.GetSubstitute(substitutes::kLoginIDField, &login_id)) {
    ReplaceSubstringsAfterOffset(&user_string, 0,
                                 substitutes::kLoginIDField,
                                 login_id);
  }

  std::string email;
  if (substitution.GetSubstitute(substitutes::kEmailField, &email)) {
    ReplaceSubstringsAfterOffset(&user_string, 0,
                                 substitutes::kEmailField,
                                 email);
  }

  onc_object->SetStringWithoutPathExpansion(fieldname, user_string);
}

void ExpandStringsInOncObject(
    const OncValueSignature& signature,
    const StringSubstitution& substitution,
    base::DictionaryValue* onc_object) {
  if (&signature == &kEAPSignature) {
    ExpandField(eap::kAnonymousIdentity, substitution, onc_object);
    ExpandField(eap::kIdentity, substitution, onc_object);
  } else if (&signature == &kL2TPSignature ||
             &signature == &kOpenVPNSignature) {
    ExpandField(vpn::kUsername, substitution, onc_object);
  }

  // Recurse into nested objects.
  for (base::DictionaryValue::Iterator it(*onc_object); !it.IsAtEnd();
       it.Advance()) {
    base::DictionaryValue* inner_object = NULL;
    if (!onc_object->GetDictionaryWithoutPathExpansion(it.key(), &inner_object))
      continue;

    const OncFieldSignature* field_signature =
        GetFieldSignature(signature, it.key());
    if (!field_signature)
      continue;

    ExpandStringsInOncObject(*field_signature->value_signature,
                             substitution, inner_object);
  }
}

void ExpandStringsInNetworks(const StringSubstitution& substitution,
                             base::ListValue* network_configs) {
  for (base::ListValue::iterator it = network_configs->begin();
       it != network_configs->end(); ++it) {
    base::DictionaryValue* network = NULL;
    (*it)->GetAsDictionary(&network);
    DCHECK(network);
    ExpandStringsInOncObject(
        kNetworkConfigurationSignature, substitution, network);
  }
}

namespace {

class OncMaskValues : public Mapper {
 public:
  static scoped_ptr<base::DictionaryValue> Mask(
      const OncValueSignature& signature,
      const base::DictionaryValue& onc_object,
      const std::string& mask) {
    OncMaskValues masker(mask);
    bool unused_error;
    return masker.MapObject(signature, onc_object, &unused_error);
  }

 protected:
  explicit OncMaskValues(const std::string& mask)
      : mask_(mask) {
  }

  virtual scoped_ptr<base::Value> MapField(
      const std::string& field_name,
      const OncValueSignature& object_signature,
      const base::Value& onc_value,
      bool* found_unknown_field,
      bool* error) OVERRIDE {
    if (FieldIsCredential(object_signature, field_name)) {
      return scoped_ptr<base::Value>(new base::StringValue(mask_));
    } else {
      return Mapper::MapField(field_name, object_signature, onc_value,
                              found_unknown_field, error);
    }
  }

  // Mask to insert in place of the sensitive values.
  std::string mask_;
};

}  // namespace

scoped_ptr<base::DictionaryValue> MaskCredentialsInOncObject(
    const OncValueSignature& signature,
    const base::DictionaryValue& onc_object,
    const std::string& mask) {
  return OncMaskValues::Mask(signature, onc_object, mask);
}

namespace {

std::string DecodePEM(const std::string& pem_encoded) {
  // The PEM block header used for DER certificates
  const char kCertificateHeader[] = "CERTIFICATE";

  // This is an older PEM marker for DER certificates.
  const char kX509CertificateHeader[] = "X509 CERTIFICATE";

  std::vector<std::string> pem_headers;
  pem_headers.push_back(kCertificateHeader);
  pem_headers.push_back(kX509CertificateHeader);

  net::PEMTokenizer pem_tokenizer(pem_encoded, pem_headers);
  std::string decoded;
  if (pem_tokenizer.GetNext()) {
    decoded = pem_tokenizer.data();
  } else {
    // If we failed to read the data as a PEM file, then try plain base64 decode
    // in case the PEM marker strings are missing. For this to work, there has
    // to be no white space, and it has to only contain the base64-encoded data.
    if (!base::Base64Decode(pem_encoded, &decoded)) {
      LOG(ERROR) << "Unable to base64 decode X509 data: " << pem_encoded;
      return std::string();
    }
  }
  return decoded;
}

CertPEMsByGUIDMap GetServerAndCACertsByGUID(
    const base::ListValue& certificates) {
  CertPEMsByGUIDMap certs_by_guid;
  for (base::ListValue::const_iterator it = certificates.begin();
      it != certificates.end(); ++it) {
    base::DictionaryValue* cert = NULL;
    (*it)->GetAsDictionary(&cert);

    std::string guid;
    cert->GetStringWithoutPathExpansion(certificate::kGUID, &guid);
    std::string cert_type;
    cert->GetStringWithoutPathExpansion(certificate::kType, &cert_type);
    if (cert_type != certificate::kServer &&
        cert_type != certificate::kAuthority) {
      continue;
    }
    std::string x509_data;
    cert->GetStringWithoutPathExpansion(certificate::kX509, &x509_data);

    std::string der = DecodePEM(x509_data);
    std::string pem;
    if (der.empty() || !net::X509Certificate::GetPEMEncodedFromDER(der, &pem)) {
      LOG(ERROR) << "Certificate with GUID " << guid
                 << " is not in PEM encoding.";
      continue;
    }
    certs_by_guid[guid] = pem;
  }

  return certs_by_guid;
}

}  // namespace

bool ParseAndValidateOncForImport(const std::string& onc_blob,
                                  ONCSource onc_source,
                                  const std::string& passphrase,
                                  base::ListValue* network_configs,
                                  base::DictionaryValue* global_network_config,
                                  base::ListValue* certificates) {
  network_configs->Clear();
  global_network_config->Clear();
  certificates->Clear();
  if (onc_blob.empty())
    return true;

  scoped_ptr<base::DictionaryValue> toplevel_onc =
      ReadDictionaryFromJson(onc_blob);
  if (toplevel_onc.get() == NULL) {
    LOG(ERROR) << "ONC loaded from " << GetSourceAsString(onc_source)
               << " is not a valid JSON dictionary.";
    return false;
  }

  // Check and see if this is an encrypted ONC file. If so, decrypt it.
  std::string onc_type;
  toplevel_onc->GetStringWithoutPathExpansion(toplevel_config::kType,
                                              &onc_type);
  if (onc_type == toplevel_config::kEncryptedConfiguration) {
    toplevel_onc = Decrypt(passphrase, *toplevel_onc);
    if (toplevel_onc.get() == NULL) {
      LOG(ERROR) << "Couldn't decrypt the ONC from "
                 << GetSourceAsString(onc_source);
      return false;
    }
  }

  bool from_policy = (onc_source == ONC_SOURCE_USER_POLICY ||
                      onc_source == ONC_SOURCE_DEVICE_POLICY);

  // Validate the ONC dictionary. We are liberal and ignore unknown field
  // names and ignore invalid field names in kRecommended arrays.
  Validator validator(false,  // Ignore unknown fields.
                      false,  // Ignore invalid recommended field names.
                      true,   // Fail on missing fields.
                      from_policy);
  validator.SetOncSource(onc_source);

  Validator::Result validation_result;
  toplevel_onc = validator.ValidateAndRepairObject(
      &kToplevelConfigurationSignature,
      *toplevel_onc,
      &validation_result);

  if (from_policy) {
    UMA_HISTOGRAM_BOOLEAN("Enterprise.ONC.PolicyValidation",
                          validation_result == Validator::VALID);
  }

  bool success = true;
  if (validation_result == Validator::VALID_WITH_WARNINGS) {
    LOG(WARNING) << "ONC from " << GetSourceAsString(onc_source)
                 << " produced warnings.";
    success = false;
  } else if (validation_result == Validator::INVALID || toplevel_onc == NULL) {
    LOG(ERROR) << "ONC from " << GetSourceAsString(onc_source)
               << " is invalid and couldn't be repaired.";
    return false;
  }

  base::ListValue* validated_certs = NULL;
  if (toplevel_onc->GetListWithoutPathExpansion(toplevel_config::kCertificates,
                                                &validated_certs)) {
    certificates->Swap(validated_certs);
  }

  base::ListValue* validated_networks = NULL;
  if (toplevel_onc->GetListWithoutPathExpansion(
          toplevel_config::kNetworkConfigurations, &validated_networks)) {
    CertPEMsByGUIDMap server_and_ca_certs =
        GetServerAndCACertsByGUID(*certificates);

    if (!ResolveServerCertRefsInNetworks(server_and_ca_certs,
                                         validated_networks)) {
      LOG(ERROR) << "Some certificate references in the ONC policy for source "
                 << GetSourceAsString(onc_source) << " could not be resolved.";
      success = false;
    }

    network_configs->Swap(validated_networks);
  }

  base::DictionaryValue* validated_global_config = NULL;
  if (toplevel_onc->GetDictionaryWithoutPathExpansion(
          toplevel_config::kGlobalNetworkConfiguration,
          &validated_global_config)) {
    global_network_config->Swap(validated_global_config);
  }

  return success;
}

scoped_refptr<net::X509Certificate> DecodePEMCertificate(
    const std::string& pem_encoded) {
  std::string decoded = DecodePEM(pem_encoded);
  scoped_refptr<net::X509Certificate> cert =
      net::X509Certificate::CreateFromBytes(decoded.data(), decoded.size());
  LOG_IF(ERROR, !cert.get()) << "Couldn't create certificate from X509 data: "
                             << decoded;
  return cert;
}

namespace {

bool GUIDRefToPEMEncoding(const CertPEMsByGUIDMap& certs_by_guid,
                          const std::string& guid_ref,
                          std::string* pem_encoded) {
  CertPEMsByGUIDMap::const_iterator it = certs_by_guid.find(guid_ref);
  if (it == certs_by_guid.end()) {
    LOG(ERROR) << "Couldn't resolve certificate reference " << guid_ref;
    return false;
  }
  *pem_encoded = it->second;
  if (pem_encoded->empty()) {
    LOG(ERROR) << "Couldn't PEM-encode certificate with GUID " << guid_ref;
    return false;
  }
  return true;
}

bool ResolveSingleCertRef(const CertPEMsByGUIDMap& certs_by_guid,
                          const std::string& key_guid_ref,
                          const std::string& key_pem,
                          base::DictionaryValue* onc_object) {
  std::string guid_ref;
  if (!onc_object->GetStringWithoutPathExpansion(key_guid_ref, &guid_ref))
    return true;

  std::string pem_encoded;
  if (!GUIDRefToPEMEncoding(certs_by_guid, guid_ref, &pem_encoded))
    return false;

  onc_object->RemoveWithoutPathExpansion(key_guid_ref, NULL);
  onc_object->SetStringWithoutPathExpansion(key_pem, pem_encoded);
  return true;
}

bool ResolveCertRefList(const CertPEMsByGUIDMap& certs_by_guid,
                        const std::string& key_guid_ref_list,
                        const std::string& key_pem_list,
                        base::DictionaryValue* onc_object) {
  const base::ListValue* guid_ref_list = NULL;
  if (!onc_object->GetListWithoutPathExpansion(key_guid_ref_list,
                                               &guid_ref_list)) {
    return true;
  }

  scoped_ptr<base::ListValue> pem_list(new base::ListValue);
  for (base::ListValue::const_iterator it = guid_ref_list->begin();
       it != guid_ref_list->end(); ++it) {
    std::string guid_ref;
    (*it)->GetAsString(&guid_ref);

    std::string pem_encoded;
    if (!GUIDRefToPEMEncoding(certs_by_guid, guid_ref, &pem_encoded))
      return false;

    pem_list->AppendString(pem_encoded);
  }

  onc_object->RemoveWithoutPathExpansion(key_guid_ref_list, NULL);
  onc_object->SetWithoutPathExpansion(key_pem_list, pem_list.release());
  return true;
}

bool ResolveSingleCertRefToList(const CertPEMsByGUIDMap& certs_by_guid,
                                const std::string& key_guid_ref,
                                const std::string& key_pem_list,
                                base::DictionaryValue* onc_object) {
  std::string guid_ref;
  if (!onc_object->GetStringWithoutPathExpansion(key_guid_ref, &guid_ref))
    return true;

  std::string pem_encoded;
  if (!GUIDRefToPEMEncoding(certs_by_guid, guid_ref, &pem_encoded))
    return false;

  scoped_ptr<base::ListValue> pem_list(new base::ListValue);
  pem_list->AppendString(pem_encoded);
  onc_object->RemoveWithoutPathExpansion(key_guid_ref, NULL);
  onc_object->SetWithoutPathExpansion(key_pem_list, pem_list.release());
  return true;
}

// Resolves the reference list at |key_guid_refs| if present and otherwise the
// single reference at |key_guid_ref|. Returns whether the respective resolving
// was successful.
bool ResolveCertRefsOrRefToList(const CertPEMsByGUIDMap& certs_by_guid,
                                const std::string& key_guid_refs,
                                const std::string& key_guid_ref,
                                const std::string& key_pem_list,
                                base::DictionaryValue* onc_object) {
  if (onc_object->HasKey(key_guid_refs)) {
    if (onc_object->HasKey(key_guid_ref)) {
      LOG(ERROR) << "Found both " << key_guid_refs << " and " << key_guid_ref
                 << ". Ignoring and removing the latter.";
      onc_object->RemoveWithoutPathExpansion(key_guid_ref, NULL);
    }
    return ResolveCertRefList(
        certs_by_guid, key_guid_refs, key_pem_list, onc_object);
  }

  // Only resolve |key_guid_ref| if |key_guid_refs| isn't present.
  return ResolveSingleCertRefToList(
      certs_by_guid, key_guid_ref, key_pem_list, onc_object);
}

bool ResolveServerCertRefsInObject(const CertPEMsByGUIDMap& certs_by_guid,
                                   const OncValueSignature& signature,
                                   base::DictionaryValue* onc_object) {
  if (&signature == &kCertificatePatternSignature) {
    if (!ResolveCertRefList(certs_by_guid, certificate::kIssuerCARef,
                            certificate::kIssuerCAPEMs, onc_object)) {
      return false;
    }
  } else if (&signature == &kEAPSignature) {
    if (!ResolveCertRefsOrRefToList(certs_by_guid,
                                    eap::kServerCARefs,
                                    eap::kServerCARef,
                                    eap::kServerCAPEMs,
                                    onc_object)) {
      return false;
    }
  } else if (&signature == &kIPsecSignature) {
    if (!ResolveCertRefsOrRefToList(certs_by_guid,
                                    ipsec::kServerCARefs,
                                    ipsec::kServerCARef,
                                    ipsec::kServerCAPEMs,
                                    onc_object)) {
      return false;
    }
  } else if (&signature == &kIPsecSignature ||
             &signature == &kOpenVPNSignature) {
    if (!ResolveSingleCertRef(certs_by_guid,
                              openvpn::kServerCertRef,
                              openvpn::kServerCertPEM,
                              onc_object) ||
        !ResolveCertRefsOrRefToList(certs_by_guid,
                                    openvpn::kServerCARefs,
                                    openvpn::kServerCARef,
                                    openvpn::kServerCAPEMs,
                                    onc_object)) {
      return false;
    }
  }

  // Recurse into nested objects.
  for (base::DictionaryValue::Iterator it(*onc_object); !it.IsAtEnd();
       it.Advance()) {
    base::DictionaryValue* inner_object = NULL;
    if (!onc_object->GetDictionaryWithoutPathExpansion(it.key(), &inner_object))
      continue;

    const OncFieldSignature* field_signature =
        GetFieldSignature(signature, it.key());
    if (!field_signature)
      continue;

    if (!ResolveServerCertRefsInObject(certs_by_guid,
                                       *field_signature->value_signature,
                                       inner_object)) {
      return false;
    }
  }
  return true;
}

}  // namespace

bool ResolveServerCertRefsInNetworks(const CertPEMsByGUIDMap& certs_by_guid,
                                     base::ListValue* network_configs) {
  bool success = true;
  for (base::ListValue::iterator it = network_configs->begin();
       it != network_configs->end(); ) {
    base::DictionaryValue* network = NULL;
    (*it)->GetAsDictionary(&network);
    if (!ResolveServerCertRefsInNetwork(certs_by_guid, network)) {
      std::string guid;
      network->GetStringWithoutPathExpansion(network_config::kGUID, &guid);
      // This might happen even with correct validation, if the referenced
      // certificate couldn't be imported.
      LOG(ERROR) << "Couldn't resolve some certificate reference of network "
                 << guid;
      it = network_configs->Erase(it, NULL);
      success = false;
      continue;
    }
    ++it;
  }
  return success;
}

bool ResolveServerCertRefsInNetwork(const CertPEMsByGUIDMap& certs_by_guid,
                                    base::DictionaryValue* network_config) {
  return ResolveServerCertRefsInObject(certs_by_guid,
                                       kNetworkConfigurationSignature,
                                       network_config);
}

}  // namespace onc
}  // namespace chromeos

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