/*
* 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.
*/
#ifndef ANDROID_VOLD_KEYMASTER_H
#define ANDROID_VOLD_KEYMASTER_H
#ifdef __cplusplus
#include <memory>
#include <string>
#include <utility>
#include <android/hardware/keymaster/3.0/IKeymasterDevice.h>
#include <keystore/authorization_set.h>
#include "Utils.h"
namespace android {
namespace vold {
using ::android::hardware::keymaster::V3_0::IKeymasterDevice;
using ::keystore::ErrorCode;
using ::keystore::KeyPurpose;
using ::keystore::AuthorizationSet;
// C++ wrappers to the Keymaster hidl interface.
// This is tailored to the needs of KeyStorage, but could be extended to be
// a more general interface.
// Wrapper for a Keymaster operation handle representing an
// ongoing Keymaster operation. Aborts the operation
// in the destructor if it is unfinished. Methods log failures
// to LOG(ERROR).
class KeymasterOperation {
public:
~KeymasterOperation();
// Is this instance valid? This is false if creation fails, and becomes
// false on finish or if an update fails.
explicit operator bool() { return mError == ErrorCode::OK; }
ErrorCode errorCode() { return mError; }
// Call "update" repeatedly until all of the input is consumed, and
// concatenate the output. Return true on success.
bool updateCompletely(const std::string& input, std::string* output);
// Finish and write the output to this string, unless pointer is null.
bool finish(std::string* output);
// Move constructor
KeymasterOperation(KeymasterOperation&& rhs) {
mDevice = std::move(rhs.mDevice);
mOpHandle = std::move(rhs.mOpHandle);
mError = std::move(rhs.mError);
}
// Construct an object in an error state for error returns
KeymasterOperation()
: mDevice{nullptr}, mOpHandle{0},
mError {ErrorCode::UNKNOWN_ERROR} {}
// Move Assignment
KeymasterOperation& operator= (KeymasterOperation&& rhs) {
mDevice = std::move(rhs.mDevice);
mOpHandle = std::move(rhs.mOpHandle);
mError = std::move(rhs.mError);
rhs.mError = ErrorCode::UNKNOWN_ERROR;
rhs.mOpHandle = 0;
return *this;
}
private:
KeymasterOperation(const sp<IKeymasterDevice>& d, uint64_t h)
: mDevice{d}, mOpHandle{h}, mError {ErrorCode::OK} {}
KeymasterOperation(ErrorCode error)
: mDevice{nullptr}, mOpHandle{0},
mError {error} {}
sp<IKeymasterDevice> mDevice;
uint64_t mOpHandle;
ErrorCode mError;
DISALLOW_COPY_AND_ASSIGN(KeymasterOperation);
friend class Keymaster;
};
// Wrapper for a Keymaster device for methods that start a KeymasterOperation or are not
// part of one.
class Keymaster {
public:
Keymaster();
// false if we failed to open the keymaster device.
explicit operator bool() { return mDevice.get() != nullptr; }
// Generate a key in the keymaster from the given params.
//bool generateKey(const AuthorizationSet& inParams, std::string* key);
// If the keymaster supports it, permanently delete a key.
bool deleteKey(const std::string& key);
// Replace stored key blob in response to KM_ERROR_KEY_REQUIRES_UPGRADE.
bool upgradeKey(const std::string& oldKey, const AuthorizationSet& inParams,
std::string* newKey);
// Begin a new cryptographic operation, collecting output parameters if pointer is non-null
KeymasterOperation begin(KeyPurpose purpose, const std::string& key,
const AuthorizationSet& inParams, AuthorizationSet* outParams);
bool isSecure();
private:
sp<hardware::keymaster::V3_0::IKeymasterDevice> mDevice;
DISALLOW_COPY_AND_ASSIGN(Keymaster);
};
} // namespace vold
} // namespace android
#endif // __cplusplus
/*
* The following functions provide C bindings to keymaster services
* needed by cryptfs scrypt. The compatibility check checks whether
* the keymaster implementation is considered secure, i.e., TEE backed.
* The create_key function generates an RSA key for signing.
* The sign_object function signes an object with the given keymaster
* key.
*/
__BEGIN_DECLS
//int keymaster_compatibility_cryptfs_scrypt();
/*int keymaster_create_key_for_cryptfs_scrypt(uint32_t rsa_key_size,
uint64_t rsa_exponent,
uint32_t ratelimit,
uint8_t* key_buffer,
uint32_t key_buffer_size,
uint32_t* key_out_size);*/
int keymaster_sign_object_for_cryptfs_scrypt(const uint8_t* key_blob,
size_t key_blob_size,
uint32_t ratelimit,
const uint8_t* object,
const size_t object_size,
uint8_t** signature_buffer,
size_t* signature_buffer_size,
uint8_t* key_buffer,
uint32_t key_buffer_size,
uint32_t* key_out_size);
__END_DECLS
#endif
