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/*
* Copyright (C) 2016 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.h"
#include <android-base/logging.h>
#include <aidl/android/hardware/security/keymint/SecurityLevel.h>
#include <aidl/android/security/maintenance/IKeystoreMaintenance.h>
#include <aidl/android/system/keystore2/Domain.h>
#include <aidl/android/system/keystore2/KeyDescriptor.h>
// Keep these in sync with system/security/keystore2/src/keystore2_main.rs
static constexpr const char keystore2_service_name[] =
"android.system.keystore2.IKeystoreService/default";
static constexpr const char maintenance_service_name[] = "android.security.maintenance";
/*
* Keep this in sync with the description for update() in
* system/hardware/interfaces/keystore2/aidl/android/system/keystore2/IKeystoreOperation.aidl
*/
static constexpr const size_t UPDATE_INPUT_MAX_SIZE = 32 * 1024; // 32 KiB
// Keep this in sync with system/sepolicy/private/keystore2_key_contexts
static constexpr const int VOLD_NAMESPACE = 100;
namespace android {
namespace vold {
namespace ks2_maint = ::aidl::android::security::maintenance;
KeymasterOperation::~KeymasterOperation() {
if (ks2Operation) ks2Operation->abort();
}
static void zeroize_vector(std::vector<uint8_t>& vec) {
memset_s(vec.data(), 0, vec.size());
}
static bool logKeystore2ExceptionIfPresent(::ndk::ScopedAStatus& rc, const std::string& func_name) {
if (rc.isOk()) return false;
auto exception_code = rc.getExceptionCode();
if (exception_code == EX_SERVICE_SPECIFIC) {
LOG(ERROR) << "keystore2 Keystore " << func_name
<< " returned service specific error: " << rc.getServiceSpecificError();
} else {
LOG(ERROR) << "keystore2 Communication with Keystore " << func_name
<< " failed error: " << exception_code;
}
return true;
}
bool KeymasterOperation::updateCompletely(const char* input, size_t inputLen,
const std::function<void(const char*, size_t)> consumer) {
if (!ks2Operation) return false;
while (inputLen != 0) {
size_t currLen = std::min(inputLen, UPDATE_INPUT_MAX_SIZE);
std::vector<uint8_t> input_vec(input, input + currLen);
inputLen -= currLen;
input += currLen;
std::optional<std::vector<uint8_t>> output;
auto rc = ks2Operation->update(input_vec, &output);
zeroize_vector(input_vec);
if (logKeystore2ExceptionIfPresent(rc, "update")) {
ks2Operation = nullptr;
return false;
}
if (!output) {
LOG(ERROR) << "Keystore2 operation update didn't return output.";
ks2Operation = nullptr;
return false;
}
consumer((const char*)output->data(), output->size());
}
return true;
}
bool KeymasterOperation::finish(std::string* output) {
std::optional<std::vector<uint8_t>> out_vec;
if (!ks2Operation) return false;
auto rc = ks2Operation->finish(std::nullopt, std::nullopt, &out_vec);
if (logKeystore2ExceptionIfPresent(rc, "finish")) {
ks2Operation = nullptr;
return false;
}
if (output) *output = std::string(out_vec->begin(), out_vec->end());
return true;
}
Keymaster::Keymaster() {
::ndk::SpAIBinder binder(AServiceManager_getService(keystore2_service_name));
auto keystore2Service = ks2::IKeystoreService::fromBinder(binder);
if (!keystore2Service) {
LOG(ERROR) << "Vold unable to connect to keystore2.";
return;
}
/*
* There are only two options available to vold for the SecurityLevel: TRUSTED_ENVIRONMENT (TEE)
* and STRONGBOX. We don't use STRONGBOX because if a TEE is present it will have Weaver, which
* already strengthens CE, so there's no additional benefit from using StrongBox.
*
* The picture is slightly more complicated because Keystore2 reports a SOFTWARE instance as
* a TEE instance when there isn't a TEE instance available, but in that case, a STRONGBOX
* instance won't be available either, so we'll still be doing the best we can.
*/
auto rc = keystore2Service->getSecurityLevel(km::SecurityLevel::TRUSTED_ENVIRONMENT,
&securityLevel);
if (logKeystore2ExceptionIfPresent(rc, "getSecurityLevel"))
LOG(ERROR) << "Vold unable to get security level from keystore2.";
}
bool Keymaster::generateKey(const km::AuthorizationSet& inParams, std::string* key) {
ks2::KeyDescriptor in_key = {
.domain = ks2::Domain::BLOB,
.alias = std::nullopt,
.nspace = VOLD_NAMESPACE,
.blob = std::nullopt,
};
ks2::KeyMetadata keyMetadata;
auto rc = securityLevel->generateKey(in_key, std::nullopt, inParams.vector_data(), 0, {},
&keyMetadata);
if (logKeystore2ExceptionIfPresent(rc, "generateKey")) return false;
if (keyMetadata.key.blob == std::nullopt) {
LOG(ERROR) << "keystore2 generated key blob was null";
return false;
}
if (key) *key = std::string(keyMetadata.key.blob->begin(), keyMetadata.key.blob->end());
zeroize_vector(keyMetadata.key.blob.value());
return true;
}
bool Keymaster::exportKey(const KeyBuffer& kmKey, std::string* key) {
bool ret = false;
ks2::KeyDescriptor storageKey = {
.domain = ks2::Domain::BLOB,
.alias = std::nullopt,
.nspace = VOLD_NAMESPACE,
};
storageKey.blob = std::make_optional<std::vector<uint8_t>>(kmKey.begin(), kmKey.end());
std::vector<uint8_t> ephemeral_key;
auto rc = securityLevel->convertStorageKeyToEphemeral(storageKey, &ephemeral_key);
if (logKeystore2ExceptionIfPresent(rc, "exportKey")) goto out;
if (key) *key = std::string(ephemeral_key.begin(), ephemeral_key.end());
ret = true;
out:
zeroize_vector(ephemeral_key);
zeroize_vector(storageKey.blob.value());
return ret;
}
bool Keymaster::deleteKey(const std::string& key) {
ks2::KeyDescriptor keyDesc = {
.domain = ks2::Domain::BLOB,
.alias = std::nullopt,
.nspace = VOLD_NAMESPACE,
};
keyDesc.blob =
std::optional<std::vector<uint8_t>>(std::vector<uint8_t>(key.begin(), key.end()));
auto rc = securityLevel->deleteKey(keyDesc);
return !logKeystore2ExceptionIfPresent(rc, "deleteKey");
}
KeymasterOperation Keymaster::begin(const std::string& key, const km::AuthorizationSet& inParams,
km::AuthorizationSet* outParams) {
ks2::KeyDescriptor keyDesc = {
.domain = ks2::Domain::BLOB,
.alias = std::nullopt,
.nspace = VOLD_NAMESPACE,
};
keyDesc.blob =
std::optional<std::vector<uint8_t>>(std::vector<uint8_t>(key.begin(), key.end()));
ks2::CreateOperationResponse cor;
auto rc = securityLevel->createOperation(keyDesc, inParams.vector_data(), true, &cor);
if (logKeystore2ExceptionIfPresent(rc, "createOperation")) {
if (rc.getExceptionCode() == EX_SERVICE_SPECIFIC)
return KeymasterOperation((km::ErrorCode)rc.getServiceSpecificError());
else
return KeymasterOperation();
}
if (!cor.iOperation) {
LOG(ERROR) << "keystore2 createOperation didn't return an operation";
return KeymasterOperation();
}
if (outParams && cor.parameters) *outParams = cor.parameters->keyParameter;
return KeymasterOperation(cor.iOperation, cor.upgradedBlob);
}
void Keymaster::earlyBootEnded() {
::ndk::SpAIBinder binder(AServiceManager_getService(maintenance_service_name));
auto maint_service = ks2_maint::IKeystoreMaintenance::fromBinder(binder);
if (!maint_service) {
LOG(ERROR) << "Unable to connect to keystore2 maintenance service for earlyBootEnded";
return;
}
auto rc = maint_service->earlyBootEnded();
logKeystore2ExceptionIfPresent(rc, "earlyBootEnded");
}
} // namespace vold
} // namespace android
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