PL286/system/keymaster/rsa_keymaster1_key.cpp

/*
 * 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.
 */

#include "rsa_keymaster1_key.h"

#include <memory>

#include <keymaster/logger.h>
#include <keymaster/soft_keymaster_context.h>

#include "rsa_keymaster1_operation.h"

using std::unique_ptr;

namespace keymaster {

RsaKeymaster1KeyFactory::RsaKeymaster1KeyFactory(const SoftKeymasterContext* context,
                                                 const Keymaster1Engine* engine)
    : RsaKeyFactory(context), engine_(engine),
      sign_factory_(new RsaKeymaster1OperationFactory(KM_PURPOSE_SIGN, engine)),
      decrypt_factory_(new RsaKeymaster1OperationFactory(KM_PURPOSE_DECRYPT, engine)),
      // For pubkey ops we can use the normal operation factories.
      verify_factory_(new RsaVerificationOperationFactory),
      encrypt_factory_(new RsaEncryptionOperationFactory) {}

static bool is_supported(uint32_t digest) {
    return digest == KM_DIGEST_NONE || digest == KM_DIGEST_SHA_2_256;
}

static void UpdateToWorkAroundUnsupportedDigests(const AuthorizationSet& key_description,
                                                 AuthorizationSet* new_description) {
    bool have_unsupported_digests = false;
    bool have_digest_none = false;
    bool have_pad_none = false;
    bool have_padding_requiring_digest = false;
    for (const keymaster_key_param_t& entry : key_description) {
        new_description->push_back(entry);

        if (entry.tag == TAG_DIGEST) {
            if (entry.enumerated == KM_DIGEST_NONE) {
                have_digest_none = true;
            } else if (!is_supported(entry.enumerated)) {
                LOG_D("Found request for unsupported digest %u", entry.enumerated);
                have_unsupported_digests = true;
            }
        }

        if (entry.tag == TAG_PADDING) {
            switch (entry.enumerated) {
            case KM_PAD_RSA_PSS:
            case KM_PAD_RSA_OAEP:
                have_padding_requiring_digest = true;
                break;
            case KM_PAD_NONE:
                have_pad_none = true;
                break;
            }
        }
    }

    if (have_unsupported_digests && !have_digest_none) {
        LOG_I("Adding KM_DIGEST_NONE to key authorization, to enable software digesting", 0);
        new_description->push_back(TAG_DIGEST, KM_DIGEST_NONE);
    }

    if (have_unsupported_digests && have_padding_requiring_digest && !have_pad_none) {
        LOG_I("Adding KM_PAD_NONE to key authorization, to enable PSS or OAEP software padding", 0);
        new_description->push_back(TAG_PADDING, KM_PAD_NONE);
    }
}

keymaster_error_t RsaKeymaster1KeyFactory::GenerateKey(const AuthorizationSet& key_description,
                                                       KeymasterKeyBlob* key_blob,
                                                       AuthorizationSet* hw_enforced,
                                                       AuthorizationSet* sw_enforced) const {
    AuthorizationSet key_params_copy;
    UpdateToWorkAroundUnsupportedDigests(key_description, &key_params_copy);
    return engine_->GenerateKey(key_params_copy, key_blob, hw_enforced, sw_enforced);
}

keymaster_error_t RsaKeymaster1KeyFactory::ImportKey(
    const AuthorizationSet& key_description, keymaster_key_format_t input_key_material_format,
    const KeymasterKeyBlob& input_key_material, KeymasterKeyBlob* output_key_blob,
    AuthorizationSet* hw_enforced, AuthorizationSet* sw_enforced) const {
    AuthorizationSet key_params_copy;
    UpdateToWorkAroundUnsupportedDigests(key_description, &key_params_copy);
    return engine_->ImportKey(key_params_copy, input_key_material_format, input_key_material,
                              output_key_blob, hw_enforced, sw_enforced);
}

keymaster_error_t RsaKeymaster1KeyFactory::LoadKey(const KeymasterKeyBlob& key_material,
                                                   const AuthorizationSet& additional_params,
                                                   const AuthorizationSet& hw_enforced,
                                                   const AuthorizationSet& sw_enforced,
                                                   UniquePtr<Key>* key) const {
    if (!key)
        return KM_ERROR_OUTPUT_PARAMETER_NULL;

    keymaster_error_t error;
    unique_ptr<RSA, RSA_Delete> rsa(engine_->BuildRsaKey(key_material, additional_params, &error));
    if (!rsa)
        return error;

    key->reset(new (std::nothrow)
                   RsaKeymaster1Key(rsa.release(), hw_enforced, sw_enforced, &error));
    if (!key->get())
        error = KM_ERROR_MEMORY_ALLOCATION_FAILED;

    if (error != KM_ERROR_OK)
        return error;

    return KM_ERROR_OK;
}

OperationFactory* RsaKeymaster1KeyFactory::GetOperationFactory(keymaster_purpose_t purpose) const {
    switch (purpose) {
    case KM_PURPOSE_SIGN:
        return sign_factory_.get();
    case KM_PURPOSE_VERIFY:
        return verify_factory_.get();
    case KM_PURPOSE_ENCRYPT:
        return encrypt_factory_.get();
    case KM_PURPOSE_DECRYPT:
        return decrypt_factory_.get();
    case KM_PURPOSE_DERIVE_KEY:
        break;
    }
    return nullptr;
}

}  // namespace keymaster