| /* |
| * Copyright 2015 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include <keymaster/contexts/pure_soft_keymaster_context.h> |
| |
| #include <memory> |
| |
| #include <openssl/aes.h> |
| #include <openssl/evp.h> |
| #include <openssl/hmac.h> |
| #include <openssl/rand.h> |
| #include <openssl/sha.h> |
| #include <openssl/x509v3.h> |
| |
| #include <keymaster/android_keymaster_utils.h> |
| #include <keymaster/key_blob_utils/auth_encrypted_key_blob.h> |
| #include <keymaster/key_blob_utils/integrity_assured_key_blob.h> |
| #include <keymaster/key_blob_utils/ocb_utils.h> |
| #include <keymaster/key_blob_utils/software_keyblobs.h> |
| #include <keymaster/km_openssl/aes_key.h> |
| #include <keymaster/km_openssl/asymmetric_key.h> |
| #include <keymaster/km_openssl/attestation_utils.h> |
| #include <keymaster/km_openssl/ec_key_factory.h> |
| #include <keymaster/km_openssl/hmac_key.h> |
| #include <keymaster/km_openssl/openssl_err.h> |
| #include <keymaster/km_openssl/openssl_utils.h> |
| #include <keymaster/km_openssl/rsa_key_factory.h> |
| #include <keymaster/km_openssl/soft_keymaster_enforcement.h> |
| #include <keymaster/km_openssl/triple_des_key.h> |
| #include <keymaster/logger.h> |
| #include <keymaster/operation.h> |
| #include <keymaster/wrapped_key.h> |
| |
| #include "soft_attestation_cert.h" |
| |
| using std::unique_ptr; |
| |
| namespace keymaster { |
| |
| PureSoftKeymasterContext::PureSoftKeymasterContext() |
| : rsa_factory_(new RsaKeyFactory(this)), ec_factory_(new EcKeyFactory(this)), |
| aes_factory_(new AesKeyFactory(this, this)), |
| tdes_factory_(new TripleDesKeyFactory(this, this)), |
| hmac_factory_(new HmacKeyFactory(this, this)), os_version_(0), os_patchlevel_(0), |
| soft_keymaster_enforcement_(64, 64) {} |
| |
| PureSoftKeymasterContext::~PureSoftKeymasterContext() {} |
| |
| keymaster_error_t PureSoftKeymasterContext::SetSystemVersion(uint32_t os_version, |
| uint32_t os_patchlevel) { |
| os_version_ = os_version; |
| os_patchlevel_ = os_patchlevel; |
| return KM_ERROR_OK; |
| } |
| |
| void PureSoftKeymasterContext::GetSystemVersion(uint32_t* os_version, uint32_t* os_patchlevel) const { |
| *os_version = os_version_; |
| *os_patchlevel = os_patchlevel_; |
| } |
| |
| KeyFactory* PureSoftKeymasterContext::GetKeyFactory(keymaster_algorithm_t algorithm) const { |
| switch (algorithm) { |
| case KM_ALGORITHM_RSA: |
| return rsa_factory_.get(); |
| case KM_ALGORITHM_EC: |
| return ec_factory_.get(); |
| case KM_ALGORITHM_AES: |
| return aes_factory_.get(); |
| case KM_ALGORITHM_TRIPLE_DES: |
| return tdes_factory_.get(); |
| case KM_ALGORITHM_HMAC: |
| return hmac_factory_.get(); |
| default: |
| return nullptr; |
| } |
| } |
| |
| static keymaster_algorithm_t supported_algorithms[] = {KM_ALGORITHM_RSA, KM_ALGORITHM_EC, |
| KM_ALGORITHM_AES, KM_ALGORITHM_HMAC}; |
| |
| keymaster_algorithm_t* |
| PureSoftKeymasterContext::GetSupportedAlgorithms(size_t* algorithms_count) const { |
| *algorithms_count = array_length(supported_algorithms); |
| return supported_algorithms; |
| } |
| |
| OperationFactory* PureSoftKeymasterContext::GetOperationFactory(keymaster_algorithm_t algorithm, |
| keymaster_purpose_t purpose) const { |
| KeyFactory* key_factory = GetKeyFactory(algorithm); |
| if (!key_factory) |
| return nullptr; |
| return key_factory->GetOperationFactory(purpose); |
| } |
| |
| keymaster_error_t PureSoftKeymasterContext::CreateKeyBlob(const AuthorizationSet& key_description, |
| const keymaster_key_origin_t origin, |
| const KeymasterKeyBlob& key_material, |
| KeymasterKeyBlob* blob, |
| AuthorizationSet* hw_enforced, |
| AuthorizationSet* sw_enforced) const { |
| keymaster_error_t error = SetKeyBlobAuthorizations(key_description, origin, os_version_, |
| os_patchlevel_, hw_enforced, sw_enforced); |
| if (error != KM_ERROR_OK) |
| return error; |
| |
| AuthorizationSet hidden; |
| error = BuildHiddenAuthorizations(key_description, &hidden, softwareRootOfTrust); |
| if (error != KM_ERROR_OK) |
| return error; |
| |
| return SerializeIntegrityAssuredBlob(key_material, hidden, *hw_enforced, *sw_enforced, blob); |
| } |
| |
| keymaster_error_t PureSoftKeymasterContext::UpgradeKeyBlob(const KeymasterKeyBlob& key_to_upgrade, |
| const AuthorizationSet& upgrade_params, |
| KeymasterKeyBlob* upgraded_key) const { |
| UniquePtr<Key> key; |
| keymaster_error_t error = ParseKeyBlob(key_to_upgrade, upgrade_params, &key); |
| if (error != KM_ERROR_OK) |
| return error; |
| |
| return UpgradeSoftKeyBlob(key, os_version_, os_patchlevel_, upgrade_params, upgraded_key); |
| } |
| |
| keymaster_error_t PureSoftKeymasterContext::ParseKeyBlob(const KeymasterKeyBlob& blob, |
| const AuthorizationSet& additional_params, |
| UniquePtr<Key>* key) const { |
| // This is a little bit complicated. |
| // |
| // The SoftKeymasterContext has to handle a lot of different kinds of key blobs. |
| // |
| // 1. New keymaster1 software key blobs. These are integrity-assured but not encrypted. The |
| // raw key material and auth sets should be extracted and returned. This is the kind |
| // produced by this context when the KeyFactory doesn't use keymaster0 to back the keys. |
| // |
| // 2. Old keymaster1 software key blobs. These are OCB-encrypted with an all-zero master key. |
| // They should be decrypted and the key material and auth sets extracted and returned. |
| // |
| // 3. Old keymaster0 software key blobs. These are raw key material with a small header tacked |
| // on the front. They don't have auth sets, so reasonable defaults are generated and |
| // returned along with the raw key material. |
| // |
| // Determining what kind of blob has arrived is somewhat tricky. What helps is that |
| // integrity-assured and OCB-encrypted blobs are self-consistent and effectively impossible to |
| // parse as anything else. Old keymaster0 software key blobs have a header. It's reasonably |
| // unlikely that hardware keys would have the same header. So anything that is neither |
| // integrity-assured nor OCB-encrypted and lacks the old software key header is assumed to be |
| // keymaster0 hardware. |
| |
| AuthorizationSet hw_enforced; |
| AuthorizationSet sw_enforced; |
| KeymasterKeyBlob key_material; |
| keymaster_error_t error; |
| |
| auto constructKey = [&, this] () mutable -> keymaster_error_t { |
| // GetKeyFactory |
| if (error != KM_ERROR_OK) return error; |
| keymaster_algorithm_t algorithm; |
| if (!hw_enforced.GetTagValue(TAG_ALGORITHM, &algorithm) && |
| !sw_enforced.GetTagValue(TAG_ALGORITHM, &algorithm)) { |
| return KM_ERROR_INVALID_ARGUMENT; |
| } |
| auto factory = GetKeyFactory(algorithm); |
| return factory->LoadKey(move(key_material), additional_params, move(hw_enforced), |
| move(sw_enforced), key); |
| }; |
| |
| AuthorizationSet hidden; |
| error = BuildHiddenAuthorizations(additional_params, &hidden, softwareRootOfTrust); |
| if (error != KM_ERROR_OK) |
| return error; |
| |
| // Assume it's an integrity-assured blob (new software-only blob, or new keymaster0-backed |
| // blob). |
| error = DeserializeIntegrityAssuredBlob(blob, hidden, &key_material, &hw_enforced, &sw_enforced); |
| if (error != KM_ERROR_INVALID_KEY_BLOB) |
| return constructKey(); |
| |
| // Wasn't an integrity-assured blob. Maybe it's an OCB-encrypted blob. |
| error = ParseOcbAuthEncryptedBlob(blob, hidden, &key_material, &hw_enforced, &sw_enforced); |
| if (error == KM_ERROR_OK) |
| LOG_D("Parsed an old keymaster1 software key", 0); |
| if (error != KM_ERROR_INVALID_KEY_BLOB) |
| return constructKey(); |
| |
| // Wasn't an OCB-encrypted blob. Maybe it's an old softkeymaster blob. |
| error = ParseOldSoftkeymasterBlob(blob, &key_material, &hw_enforced, &sw_enforced); |
| if (error == KM_ERROR_OK) |
| LOG_D("Parsed an old sofkeymaster key", 0); |
| |
| return constructKey(); |
| } |
| |
| keymaster_error_t PureSoftKeymasterContext::DeleteKey(const KeymasterKeyBlob& /* blob */) const { |
| // Nothing to do for software-only contexts. |
| return KM_ERROR_OK; |
| } |
| |
| keymaster_error_t PureSoftKeymasterContext::DeleteAllKeys() const { |
| return KM_ERROR_OK; |
| } |
| |
| keymaster_error_t PureSoftKeymasterContext::AddRngEntropy(const uint8_t* buf, size_t length) const { |
| // XXX TODO according to boringssl openssl/rand.h RAND_add is deprecated and does |
| // nothing |
| RAND_add(buf, length, 0 /* Don't assume any entropy is added to the pool. */); |
| return KM_ERROR_OK; |
| } |
| |
| keymaster_error_t PureSoftKeymasterContext::GenerateAttestation(const Key& key, |
| const AuthorizationSet& attest_params, |
| CertChainPtr* cert_chain) const { |
| |
| keymaster_error_t error = KM_ERROR_OK; |
| keymaster_algorithm_t key_algorithm; |
| if (!key.authorizations().GetTagValue(TAG_ALGORITHM, &key_algorithm)) { |
| return KM_ERROR_UNKNOWN_ERROR; |
| } |
| |
| if ((key_algorithm != KM_ALGORITHM_RSA && key_algorithm != KM_ALGORITHM_EC)) |
| return KM_ERROR_INCOMPATIBLE_ALGORITHM; |
| |
| // We have established that the given key has the correct algorithm, and because this is the |
| // SoftKeymasterContext we can assume that the Key is an AsymmetricKey. So we can downcast. |
| const AsymmetricKey& asymmetric_key = static_cast<const AsymmetricKey&>(key); |
| |
| auto attestation_chain = getAttestationChain(key_algorithm, &error); |
| if (error != KM_ERROR_OK) return error; |
| |
| auto attestation_key = getAttestationKey(key_algorithm, &error); |
| if (error != KM_ERROR_OK) return error; |
| |
| return generate_attestation(asymmetric_key, attest_params, |
| *attestation_chain, *attestation_key, *this, cert_chain); |
| } |
| |
| static keymaster_error_t TranslateAuthorizationSetError(AuthorizationSet::Error err) { |
| switch (err) { |
| case AuthorizationSet::OK: |
| return KM_ERROR_OK; |
| case AuthorizationSet::ALLOCATION_FAILURE: |
| return KM_ERROR_MEMORY_ALLOCATION_FAILED; |
| case AuthorizationSet::MALFORMED_DATA: |
| return KM_ERROR_UNKNOWN_ERROR; |
| } |
| return KM_ERROR_OK; |
| } |
| |
| keymaster_error_t PureSoftKeymasterContext::UnwrapKey( |
| const KeymasterKeyBlob& wrapped_key_blob, const KeymasterKeyBlob& wrapping_key_blob, |
| const AuthorizationSet& /* wrapping_key_params */, const KeymasterKeyBlob& masking_key, |
| AuthorizationSet* wrapped_key_params, keymaster_key_format_t* wrapped_key_format, |
| KeymasterKeyBlob* wrapped_key_material) const { |
| keymaster_error_t error = KM_ERROR_OK; |
| |
| if (!wrapped_key_material) return KM_ERROR_UNEXPECTED_NULL_POINTER; |
| |
| // Parse wrapped key data |
| KeymasterBlob iv; |
| KeymasterKeyBlob transit_key; |
| KeymasterKeyBlob secure_key; |
| KeymasterBlob tag; |
| KeymasterBlob wrapped_key_description; |
| error = parse_wrapped_key(wrapped_key_blob, &iv, &transit_key, &secure_key, &tag, |
| wrapped_key_params, wrapped_key_format, &wrapped_key_description); |
| if (error != KM_ERROR_OK) return error; |
| |
| UniquePtr<Key> key; |
| auto wrapping_key_params = AuthorizationSetBuilder() |
| .RsaEncryptionKey(2048, 65537) |
| .Digest(KM_DIGEST_SHA1) |
| .Padding(KM_PAD_RSA_OAEP) |
| .Authorization(TAG_PURPOSE, KM_PURPOSE_WRAP) |
| .build(); |
| error = ParseKeyBlob(wrapping_key_blob, wrapping_key_params, &key); |
| if (error != KM_ERROR_OK) return error; |
| |
| // Ensure the wrapping key has the right purpose |
| if (!key->hw_enforced().Contains(TAG_PURPOSE, KM_PURPOSE_WRAP) && |
| !key->sw_enforced().Contains(TAG_PURPOSE, KM_PURPOSE_WRAP)) { |
| return KM_ERROR_INCOMPATIBLE_PURPOSE; |
| } |
| |
| auto operation_factory = GetOperationFactory(KM_ALGORITHM_RSA, KM_PURPOSE_DECRYPT); |
| if (!operation_factory) return KM_ERROR_UNKNOWN_ERROR; |
| |
| AuthorizationSet out_params; |
| OperationPtr operation( |
| operation_factory->CreateOperation(move(*key), wrapping_key_params, &error)); |
| if (!operation.get()) return error; |
| |
| error = operation->Begin(wrapping_key_params, &out_params); |
| if (error != KM_ERROR_OK) return error; |
| |
| Buffer input; |
| Buffer output; |
| if (!input.Reinitialize(transit_key.key_material, transit_key.key_material_size)) { |
| return KM_ERROR_MEMORY_ALLOCATION_FAILED; |
| } |
| |
| error = operation->Finish(wrapping_key_params, input, Buffer() /* signature */, &out_params, |
| &output); |
| if (error != KM_ERROR_OK) return error; |
| |
| // decrypt the encrypted key material with the transit key |
| KeymasterKeyBlob key_material = {output.peek_read(), output.available_read()}; |
| |
| // XOR the transit key with the masking key |
| if (key_material.key_material_size != masking_key.key_material_size) { |
| return KM_ERROR_INVALID_ARGUMENT; |
| } |
| for (size_t i = 0; i < key_material.key_material_size; i++) { |
| key_material.writable_data()[i] ^= masking_key.key_material[i]; |
| } |
| |
| auto transit_key_authorizations = AuthorizationSetBuilder() |
| .AesEncryptionKey(256) |
| .Padding(KM_PAD_NONE) |
| .Authorization(TAG_BLOCK_MODE, KM_MODE_GCM) |
| .Authorization(TAG_NONCE, iv) |
| .Authorization(TAG_MIN_MAC_LENGTH, 128) |
| .build(); |
| if (transit_key_authorizations.is_valid() != AuthorizationSet::Error::OK) { |
| return TranslateAuthorizationSetError(transit_key_authorizations.is_valid()); |
| } |
| auto gcm_params = AuthorizationSetBuilder() |
| .Padding(KM_PAD_NONE) |
| .Authorization(TAG_BLOCK_MODE, KM_MODE_GCM) |
| .Authorization(TAG_NONCE, iv) |
| .Authorization(TAG_MAC_LENGTH, 128) |
| .build(); |
| if (gcm_params.is_valid() != AuthorizationSet::Error::OK) { |
| return TranslateAuthorizationSetError(transit_key_authorizations.is_valid()); |
| } |
| |
| auto aes_factory = GetKeyFactory(KM_ALGORITHM_AES); |
| if (!aes_factory) return KM_ERROR_UNKNOWN_ERROR; |
| |
| UniquePtr<Key> aes_key; |
| error = aes_factory->LoadKey(move(key_material), gcm_params, move(transit_key_authorizations), |
| AuthorizationSet(), &aes_key); |
| if (error != KM_ERROR_OK) return error; |
| |
| auto aes_operation_factory = GetOperationFactory(KM_ALGORITHM_AES, KM_PURPOSE_DECRYPT); |
| if (!aes_operation_factory) return KM_ERROR_UNKNOWN_ERROR; |
| |
| OperationPtr aes_operation( |
| aes_operation_factory->CreateOperation(move(*aes_key), gcm_params, &error)); |
| if (!aes_operation.get()) return error; |
| |
| error = aes_operation->Begin(gcm_params, &out_params); |
| if (error != KM_ERROR_OK) return error; |
| |
| size_t consumed = 0; |
| Buffer encrypted_key, plaintext; |
| if (!plaintext.Reinitialize(secure_key.key_material_size + tag.data_length)) { |
| return KM_ERROR_MEMORY_ALLOCATION_FAILED; |
| } |
| if (!encrypted_key.Reinitialize(secure_key.key_material_size + tag.data_length)) { |
| return KM_ERROR_MEMORY_ALLOCATION_FAILED; |
| } |
| if (!encrypted_key.write(secure_key.key_material, secure_key.key_material_size)) { |
| return KM_ERROR_UNKNOWN_ERROR; |
| } |
| if (!encrypted_key.write(tag.data, tag.data_length)) { |
| return KM_ERROR_UNKNOWN_ERROR; |
| } |
| |
| AuthorizationSet update_outparams; |
| auto update_params = AuthorizationSetBuilder() |
| .Authorization(TAG_ASSOCIATED_DATA, wrapped_key_description.data, |
| wrapped_key_description.data_length) |
| .build(); |
| if (update_params.is_valid() != AuthorizationSet::Error::OK) { |
| return TranslateAuthorizationSetError(transit_key_authorizations.is_valid()); |
| } |
| |
| error = aes_operation->Update(update_params, encrypted_key, &update_outparams, &plaintext, |
| &consumed); |
| if (error != KM_ERROR_OK) return error; |
| |
| AuthorizationSet finish_params, finish_out_params; |
| Buffer finish_input; |
| error = aes_operation->Finish(finish_params, finish_input, Buffer() /* signature */, |
| &finish_out_params, &plaintext); |
| if (error != KM_ERROR_OK) return error; |
| |
| *wrapped_key_material = {plaintext.peek_read(), plaintext.available_read()}; |
| if (!wrapped_key_material->key_material && plaintext.peek_read()) { |
| return KM_ERROR_MEMORY_ALLOCATION_FAILED; |
| } |
| |
| return error; |
| } |
| |
| } // namespace keymaster |