trusty_keymaster_context.h

/*
 * Copyright 2015 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 TRUSTY_APP_KEYMASTER_TRUSTY_KEYMASTER_CONTEXT_H_
#define TRUSTY_APP_KEYMASTER_TRUSTY_KEYMASTER_CONTEXT_H_

#include <stdlib.h>

#include <UniquePtr.h>

#include <keymaster/keymaster_context.h>

#include "trusty_keymaster_enforcement.h"

namespace keymaster {

class KeyFactory;

static const int kAuthTokenKeySize = 32;

class TrustyKeymasterContext : public KeymasterContext {
  public:
    TrustyKeymasterContext();

    keymaster_security_level_t GetSecurityLevel() const override {
        return KM_SECURITY_LEVEL_TRUSTED_ENVIRONMENT;
    }

    keymaster_error_t SetSystemVersion(uint32_t /* os_version */,
                                       uint32_t /* os_patchlevel */) override {
        return KM_ERROR_UNIMPLEMENTED;
    }

    void GetSystemVersion(uint32_t* os_version, uint32_t* os_patchlevel) const override {};

    KeyFactory* GetKeyFactory(keymaster_algorithm_t algorithm) const override;
    OperationFactory* GetOperationFactory(keymaster_algorithm_t algorithm,
                                          keymaster_purpose_t purpose) const override;
    keymaster_algorithm_t* GetSupportedAlgorithms(size_t* algorithms_count) const override;

    keymaster_error_t CreateKeyBlob(const AuthorizationSet& key_description,
                                    keymaster_key_origin_t origin,
                                    const KeymasterKeyBlob& key_material, KeymasterKeyBlob* blob,
                                    AuthorizationSet* hw_enforced,
                                    AuthorizationSet* sw_enforced) const override;

    keymaster_error_t UpgradeKeyBlob(const KeymasterKeyBlob& key_to_upgrade,
                                     const AuthorizationSet& upgrade_params,
                                     KeymasterKeyBlob* upgraded_key) const override {
        return KM_ERROR_UNIMPLEMENTED;
    }

    keymaster_error_t ParseKeyBlob(const KeymasterKeyBlob& blob,
                                   const AuthorizationSet& additional_params,
                                   KeymasterKeyBlob* key_material, AuthorizationSet* hw_enforced,
                                   AuthorizationSet* sw_enforced) const override;

    keymaster_error_t AddRngEntropy(const uint8_t* buf, size_t length) const override;

    keymaster_error_t GenerateRandom(uint8_t* buf, size_t length) const override;

    keymaster_error_t GetAuthTokenKey(keymaster_key_blob_t* key) const;

    KeymasterEnforcement* enforcement_policy() override { return &enforcement_policy_; }

    EVP_PKEY* AttestationKey(keymaster_algorithm_t algorithm,
                             keymaster_error_t* error) const override {
        *error = KM_ERROR_UNIMPLEMENTED;
        return nullptr;
    };

    keymaster_cert_chain_t* AttestationChain(keymaster_algorithm_t algorithm,
                                             keymaster_error_t* error) const override {
        *error = KM_ERROR_UNIMPLEMENTED;
        return nullptr;
    };

    keymaster_error_t GenerateUniqueId(uint64_t creation_date_time,
                                       const keymaster_blob_t& application_id,
                                       bool reset_since_rotation,
                                       Buffer* unique_id) const override {
        return KM_ERROR_UNIMPLEMENTED;
    }

  private:
    bool SeedRngIfNeeded() const;
    bool ShouldReseedRng() const;
    bool ReseedRng();
    bool InitializeAuthTokenKey();
    keymaster_error_t DeriveMasterKey(KeymasterKeyBlob* master_key) const;

    TrustyKeymasterEnforcement enforcement_policy_;

    UniquePtr<KeyFactory> aes_factory_;
    UniquePtr<KeyFactory> ec_factory_;
    UniquePtr<KeyFactory> hmac_factory_;
    UniquePtr<KeyFactory> rsa_factory_;

    UniquePtr<uint8_t[]> master_key_;
    size_t root_of_trust_size_;
    bool rng_initialized_;
    mutable int calls_since_reseed_;
    uint8_t auth_token_key_[kAuthTokenKeySize];
    bool auth_token_key_initialized_;
};

}  // namespace keymaster

#endif  // TRUSTY_APP_KEYMASTER_TRUSTY_KEYMASTER_CONTEXT_H_