234 lines
8.6 KiB
C++
234 lines
8.6 KiB
C++
/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "Keymaster.h"
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#include <android-base/logging.h>
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#include <aidl/android/hardware/security/keymint/SecurityLevel.h>
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#include <aidl/android/security/maintenance/IKeystoreMaintenance.h>
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#include <aidl/android/system/keystore2/Domain.h>
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#include <aidl/android/system/keystore2/EphemeralStorageKeyResponse.h>
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#include <aidl/android/system/keystore2/KeyDescriptor.h>
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// Keep these in sync with system/security/keystore2/src/keystore2_main.rs
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static constexpr const char keystore2_service_name[] =
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"android.system.keystore2.IKeystoreService/default";
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static constexpr const char maintenance_service_name[] = "android.security.maintenance";
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/*
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* Keep this in sync with the description for update() in
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* system/hardware/interfaces/keystore2/aidl/android/system/keystore2/IKeystoreOperation.aidl
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*/
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static constexpr const size_t UPDATE_INPUT_MAX_SIZE = 32 * 1024; // 32 KiB
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// Keep this in sync with system/sepolicy/private/keystore2_key_contexts
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static constexpr const int VOLD_NAMESPACE = 100;
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namespace android {
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namespace vold {
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namespace ks2_maint = ::aidl::android::security::maintenance;
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KeymasterOperation::~KeymasterOperation() {
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if (ks2Operation) ks2Operation->abort();
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}
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static void zeroize_vector(std::vector<uint8_t>& vec) {
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memset_s(vec.data(), 0, vec.size());
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}
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static bool logKeystore2ExceptionIfPresent(::ndk::ScopedAStatus& rc, const std::string& func_name) {
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if (rc.isOk()) return false;
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auto exception_code = rc.getExceptionCode();
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if (exception_code == EX_SERVICE_SPECIFIC) {
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LOG(ERROR) << "keystore2 Keystore " << func_name
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<< " returned service specific error: " << rc.getServiceSpecificError();
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} else {
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LOG(ERROR) << "keystore2 Communication with Keystore " << func_name
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<< " failed error: " << exception_code;
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}
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return true;
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}
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bool KeymasterOperation::updateCompletely(const char* input, size_t inputLen,
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const std::function<void(const char*, size_t)> consumer) {
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if (!ks2Operation) return false;
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while (inputLen != 0) {
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size_t currLen = std::min(inputLen, UPDATE_INPUT_MAX_SIZE);
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std::vector<uint8_t> input_vec(input, input + currLen);
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inputLen -= currLen;
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input += currLen;
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std::optional<std::vector<uint8_t>> output;
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auto rc = ks2Operation->update(input_vec, &output);
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zeroize_vector(input_vec);
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if (logKeystore2ExceptionIfPresent(rc, "update")) {
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ks2Operation = nullptr;
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return false;
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}
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if (output) consumer((const char*)output->data(), output->size());
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}
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return true;
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}
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bool KeymasterOperation::finish(std::string* output) {
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std::optional<std::vector<uint8_t>> out_vec;
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if (!ks2Operation) return false;
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auto rc = ks2Operation->finish(std::nullopt, std::nullopt, &out_vec);
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if (logKeystore2ExceptionIfPresent(rc, "finish")) {
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ks2Operation = nullptr;
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return false;
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}
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if (output) *output = std::string(out_vec->begin(), out_vec->end());
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return true;
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}
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Keymaster::Keymaster() {
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::ndk::SpAIBinder binder(AServiceManager_getService(keystore2_service_name));
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auto keystore2Service = ks2::IKeystoreService::fromBinder(binder);
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if (!keystore2Service) {
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LOG(ERROR) << "Vold unable to connect to keystore2.";
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return;
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}
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/*
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* There are only two options available to vold for the SecurityLevel: TRUSTED_ENVIRONMENT (TEE)
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* and STRONGBOX. We don't use STRONGBOX because if a TEE is present it will have Weaver, which
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* already strengthens CE, so there's no additional benefit from using StrongBox.
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*
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* The picture is slightly more complicated because Keystore2 reports a SOFTWARE instance as
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* a TEE instance when there isn't a TEE instance available, but in that case, a STRONGBOX
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* instance won't be available either, so we'll still be doing the best we can.
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*/
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auto rc = keystore2Service->getSecurityLevel(km::SecurityLevel::TRUSTED_ENVIRONMENT,
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&securityLevel);
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if (logKeystore2ExceptionIfPresent(rc, "getSecurityLevel"))
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LOG(ERROR) << "Vold unable to get security level from keystore2.";
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}
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bool Keymaster::generateKey(const km::AuthorizationSet& inParams, std::string* key) {
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ks2::KeyDescriptor in_key = {
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.domain = ks2::Domain::BLOB,
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.alias = std::nullopt,
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.nspace = VOLD_NAMESPACE,
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.blob = std::nullopt,
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};
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ks2::KeyMetadata keyMetadata;
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auto rc = securityLevel->generateKey(in_key, std::nullopt, inParams.vector_data(), 0, {},
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&keyMetadata);
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if (logKeystore2ExceptionIfPresent(rc, "generateKey")) return false;
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if (keyMetadata.key.blob == std::nullopt) {
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LOG(ERROR) << "keystore2 generated key blob was null";
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return false;
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}
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if (key) *key = std::string(keyMetadata.key.blob->begin(), keyMetadata.key.blob->end());
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zeroize_vector(keyMetadata.key.blob.value());
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return true;
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}
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bool Keymaster::exportKey(const KeyBuffer& kmKey, std::string* key) {
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bool ret = false;
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ks2::KeyDescriptor storageKey = {
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.domain = ks2::Domain::BLOB,
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.alias = std::nullopt,
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.nspace = VOLD_NAMESPACE,
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};
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storageKey.blob = std::make_optional<std::vector<uint8_t>>(kmKey.begin(), kmKey.end());
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ks2::EphemeralStorageKeyResponse ephemeral_key_response;
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auto rc = securityLevel->convertStorageKeyToEphemeral(storageKey, &ephemeral_key_response);
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if (logKeystore2ExceptionIfPresent(rc, "exportKey")) goto out;
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if (key)
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*key = std::string(ephemeral_key_response.ephemeralKey.begin(),
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ephemeral_key_response.ephemeralKey.end());
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// TODO b/185811713 store the upgraded key blob if provided and delete the old key blob.
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ret = true;
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out:
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zeroize_vector(ephemeral_key_response.ephemeralKey);
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zeroize_vector(storageKey.blob.value());
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return ret;
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}
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bool Keymaster::deleteKey(const std::string& key) {
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ks2::KeyDescriptor keyDesc = {
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.domain = ks2::Domain::BLOB,
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.alias = std::nullopt,
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.nspace = VOLD_NAMESPACE,
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};
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keyDesc.blob =
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std::optional<std::vector<uint8_t>>(std::vector<uint8_t>(key.begin(), key.end()));
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auto rc = securityLevel->deleteKey(keyDesc);
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return !logKeystore2ExceptionIfPresent(rc, "deleteKey");
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}
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KeymasterOperation Keymaster::begin(const std::string& key, const km::AuthorizationSet& inParams,
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km::AuthorizationSet* outParams) {
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ks2::KeyDescriptor keyDesc = {
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.domain = ks2::Domain::BLOB,
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.alias = std::nullopt,
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.nspace = VOLD_NAMESPACE,
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};
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keyDesc.blob =
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std::optional<std::vector<uint8_t>>(std::vector<uint8_t>(key.begin(), key.end()));
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ks2::CreateOperationResponse cor;
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auto rc = securityLevel->createOperation(keyDesc, inParams.vector_data(), true, &cor);
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if (logKeystore2ExceptionIfPresent(rc, "createOperation")) {
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if (rc.getExceptionCode() == EX_SERVICE_SPECIFIC)
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return KeymasterOperation((km::ErrorCode)rc.getServiceSpecificError());
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else
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return KeymasterOperation();
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}
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if (!cor.iOperation) {
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LOG(ERROR) << "keystore2 createOperation didn't return an operation";
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return KeymasterOperation();
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}
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if (outParams && cor.parameters) *outParams = cor.parameters->keyParameter;
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return KeymasterOperation(cor.iOperation, cor.upgradedBlob);
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}
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void Keymaster::earlyBootEnded() {
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::ndk::SpAIBinder binder(AServiceManager_getService(maintenance_service_name));
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auto maint_service = ks2_maint::IKeystoreMaintenance::fromBinder(binder);
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if (!maint_service) {
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LOG(ERROR) << "Unable to connect to keystore2 maintenance service for earlyBootEnded";
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return;
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}
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auto rc = maint_service->earlyBootEnded();
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logKeystore2ExceptionIfPresent(rc, "earlyBootEnded");
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}
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} // namespace vold
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} // namespace android
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