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/*
* Copyright 2023 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 "host/commands/secure_env/oemlock/oemlock.h"
namespace cuttlefish {
namespace oemlock {
namespace {
constexpr char kStateKey[] = "oemlock_state";
constexpr int kAllowedByCarrierBit = 0;
constexpr int kAllowedByDeviceBit = 1;
constexpr int kOemLockedBit = 2;
// Default state is allowed_by_carrier = true
// allowed_by_device = false
// locked = true
constexpr uint8_t kDefaultState = 0 | (1 << kAllowedByCarrierBit) | (1 << kOemLockedBit);
Result<void> InitializeDefaultState(secure_env::Storage& storage) {
if (storage.Exists()) { return {}; };
auto data = CF_EXPECT(secure_env::CreateStorageData(&kDefaultState, sizeof(kDefaultState)));
CF_EXPECT(storage.Write(kStateKey, *data));
return {};
}
Result<bool> ReadFlag(secure_env::Storage& storage, int bit) {
auto data = CF_EXPECT(storage.Read(kStateKey));
auto state = CF_EXPECT(data->asUint8());
return (state >> bit) & 1;
}
Result<void> WriteFlag(secure_env::Storage& storage, int bit, bool value) {
auto data = CF_EXPECT(storage.Read(kStateKey));
auto state = CF_EXPECT(data->asUint8());
value ? state |= (1 << bit) : state &= ~(1 << bit);
auto data_to_write = CF_EXPECT(secure_env::CreateStorageData(&state, sizeof(state)));
CF_EXPECT(storage.Write(kStateKey, *data_to_write));
return {};
}
} // namespace
OemLock::OemLock(secure_env::Storage& storage) : storage_(storage) {
auto result = InitializeDefaultState(storage_);
if (!result.ok()) {
LOG(FATAL) << "Failed to initialize default state for OemLock TEE storage: "
<< result.error().Message();
}
}
Result<bool> OemLock::IsOemUnlockAllowedByCarrier() const {
return CF_EXPECT(ReadFlag(storage_, kAllowedByCarrierBit));
}
Result<bool> OemLock::IsOemUnlockAllowedByDevice() const {
return CF_EXPECT(ReadFlag(storage_, kAllowedByDeviceBit));
}
Result<bool> OemLock::IsOemUnlockAllowed() const {
auto data = CF_EXPECT(storage_.Read(kStateKey));
auto state = CF_EXPECT(data->asUint8());
const bool allowed_by_device = (state >> kAllowedByDeviceBit) & 1;
const bool allowed_by_carrier = (state >> kAllowedByCarrierBit) & 1;
return allowed_by_device && allowed_by_carrier;
}
Result<bool> OemLock::IsOemLocked() const {
return CF_EXPECT(ReadFlag(storage_, kOemLockedBit));
}
Result<void> OemLock::SetOemUnlockAllowedByCarrier(bool allowed) {
CF_EXPECT(WriteFlag(storage_, kAllowedByCarrierBit, allowed));
return {};
}
Result<void> OemLock::SetOemUnlockAllowedByDevice(bool allowed) {
CF_EXPECT(WriteFlag(storage_, kAllowedByDeviceBit, allowed));
return {};
}
Result<void> OemLock::SetOemLocked(bool locked) {
CF_EXPECT(WriteFlag(storage_, kOemLockedBit, locked));
return {};
}
} // namespace oemlock
} // namespace cuttlefish
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