/*
* 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_TWRP_KEYMASTER_H
#define ANDROID_TWRP_KEYMASTER_H
#include "KeyBuffer.h"
#include <memory>
#include <string>
#include <utility>
#include <android-base/macros.h>
#include <keymasterV4_0/Keymaster.h>
#include <keymasterV4_0/authorization_set.h>
namespace android {
namespace vold {
namespace km = ::android::hardware::keymaster::V4_0;
using KmDevice = km::support::Keymaster;
// 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 == km::ErrorCode::OK; }
km::ErrorCode errorCode() { return mError; }
// Call "update" repeatedly until all of the input is consumed, and
// concatenate the output. Return true on success.
template <class TI, class TO>
bool updateCompletely(TI& input, TO* output) {
if (output) output->clear();
return updateCompletely(input.data(), input.size(), [&](const char* b, size_t n) {
if (output) std::copy(b, b + n, std::back_inserter(*output));
});
}
// Finish and write the output to this string, unless pointer is null.
bool finish(std::string* output);
// Move constructor
KeymasterOperation(KeymasterOperation&& rhs) { *this = std::move(rhs); }
// Construct an object in an error state for error returns
KeymasterOperation() : mDevice{nullptr}, mOpHandle{0}, mError{km::ErrorCode::UNKNOWN_ERROR} {}
// Move Assignment
KeymasterOperation& operator=(KeymasterOperation&& rhs) {
mDevice = rhs.mDevice;
rhs.mDevice = nullptr;
mOpHandle = rhs.mOpHandle;
rhs.mOpHandle = 0;
mError = rhs.mError;
rhs.mError = km::ErrorCode::UNKNOWN_ERROR;
return *this;
}
private:
KeymasterOperation(KmDevice* d, uint64_t h)
: mDevice{d}, mOpHandle{h}, mError{km::ErrorCode::OK} {}
KeymasterOperation(km::ErrorCode error) : mDevice{nullptr}, mOpHandle{0}, mError{error} {}
bool updateCompletely(const char* input, size_t inputLen,
const std::function<void(const char*, size_t)> consumer);
KmDevice* mDevice;
uint64_t mOpHandle;
km::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 km::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 km::AuthorizationSet& inParams,
std::string* newKey);
// Begin a new cryptographic operation, collecting output parameters if pointer is non-null
KeymasterOperation begin(km::KeyPurpose purpose, const std::string& key,
const km::AuthorizationSet& inParams,
const km::HardwareAuthToken& authToken,
km::AuthorizationSet* outParams);
bool isSecure();
private:
std::unique_ptr<KmDevice> mDevice;
DISALLOW_COPY_AND_ASSIGN(Keymaster);
static bool hmacKeyGenerated;
};
} // namespace vold
} // namespace android
// FIXME no longer needed now cryptfs is in C++.
/*
* 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.
*/
/* Return values for keymaster_sign_object_for_cryptfs_scrypt */
enum class KeymasterSignResult {
ok = 0,
error = -1,
upgrade = -2,
};
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_upgrade_key_for_cryptfs_scrypt(uint32_t rsa_key_size, uint64_t rsa_exponent,
uint32_t ratelimit, const uint8_t* key_blob,
size_t key_blob_size, uint8_t* key_buffer,
uint32_t key_buffer_size, uint32_t* key_out_size);
KeymasterSignResult 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);
#endif
