/*
* 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.
*/
#include "Keymaster.h"
#include <android-base/logging.h>
#include <keymasterV4_0/authorization_set.h>
#include <keymasterV4_0/keymaster_utils.h>
namespace android {
namespace vold {
using ::android::hardware::hidl_string;
using ::android::hardware::hidl_vec;
using ::android::hardware::keymaster::V4_0::SecurityLevel;
KeymasterOperation::~KeymasterOperation() {
if (mDevice) mDevice->abort(mOpHandle);
}
bool KeymasterOperation::updateCompletely(const char* input, size_t inputLen,
const std::function<void(const char*, size_t)> consumer) {
uint32_t inputConsumed = 0;
km::ErrorCode km_error;
auto hidlCB = [&](km::ErrorCode ret, uint32_t inputConsumedDelta,
const hidl_vec<km::KeyParameter>& /*ignored*/,
const hidl_vec<uint8_t>& _output) {
km_error = ret;
if (km_error != km::ErrorCode::OK) return;
inputConsumed += inputConsumedDelta;
consumer(reinterpret_cast<const char*>(&_output[0]), _output.size());
};
while (inputConsumed != inputLen) {
size_t toRead = static_cast<size_t>(inputLen - inputConsumed);
auto inputBlob = km::support::blob2hidlVec(
reinterpret_cast<const uint8_t*>(&input[inputConsumed]), toRead);
auto error = mDevice->update(mOpHandle, hidl_vec<km::KeyParameter>(), inputBlob,
km::HardwareAuthToken(), km::VerificationToken(), hidlCB);
if (!error.isOk()) {
LOG(ERROR) << "update failed: " << error.description();
mDevice = nullptr;
return false;
}
if (km_error != km::ErrorCode::OK) {
LOG(ERROR) << "update failed, code " << int32_t(km_error);
mDevice = nullptr;
return false;
}
if (inputConsumed > inputLen) {
LOG(ERROR) << "update reported too much input consumed";
mDevice = nullptr;
return false;
}
}
return true;
}
bool KeymasterOperation::finish(std::string* output) {
km::ErrorCode km_error;
auto hidlCb = [&](km::ErrorCode ret, const hidl_vec<km::KeyParameter>& /*ignored*/,
const hidl_vec<uint8_t>& _output) {
km_error = ret;
if (km_error != km::ErrorCode::OK) return;
if (output) output->assign(reinterpret_cast<const char*>(&_output[0]), _output.size());
};
auto error = mDevice->finish(mOpHandle, hidl_vec<km::KeyParameter>(), hidl_vec<uint8_t>(),
hidl_vec<uint8_t>(), km::HardwareAuthToken(),
km::VerificationToken(), hidlCb);
mDevice = nullptr;
if (!error.isOk()) {
LOG(ERROR) << "finish failed: " << error.description();
return false;
}
if (km_error != km::ErrorCode::OK) {
LOG(ERROR) << "finish failed, code " << int32_t(km_error);
return false;
}
return true;
}
/* static */ bool Keymaster::hmacKeyGenerated = false;
Keymaster::Keymaster() {
auto devices = KmDevice::enumerateAvailableDevices();
if (!hmacKeyGenerated) {
KmDevice::performHmacKeyAgreement(devices);
hmacKeyGenerated = true;
}
for (auto& dev : devices) {
// Do not use StrongBox for device encryption / credential encryption. If a security chip
// is present it will have Weaver, which already strengthens CE. We get no additional
// benefit from using StrongBox here, so skip it.
if (dev->halVersion().securityLevel != SecurityLevel::STRONGBOX) {
mDevice = std::move(dev);
break;
}
}
if (!mDevice) return;
auto& version = mDevice->halVersion();
LOG(INFO) << "Using " << version.keymasterName << " from " << version.authorName
<< " for encryption. Security level: " << toString(version.securityLevel)
<< ", HAL: " << mDevice->descriptor() << "/" << mDevice->instanceName();
}
bool Keymaster::generateKey(const km::AuthorizationSet& inParams, std::string* key) {
km::ErrorCode km_error;
auto hidlCb = [&](km::ErrorCode ret, const hidl_vec<uint8_t>& keyBlob,
const km::KeyCharacteristics& /*ignored*/) {
km_error = ret;
if (km_error != km::ErrorCode::OK) return;
if (key) key->assign(reinterpret_cast<const char*>(&keyBlob[0]), keyBlob.size());
};
auto error = mDevice->generateKey(inParams.hidl_data(), hidlCb);
if (!error.isOk()) {
LOG(ERROR) << "generate_key failed: " << error.description();
return false;
}
if (km_error != km::ErrorCode::OK) {
LOG(ERROR) << "generate_key failed, code " << int32_t(km_error);
return false;
}
return true;
}
bool Keymaster::deleteKey(const std::string& key) {
auto keyBlob = km::support::blob2hidlVec(key);
auto error = mDevice->deleteKey(keyBlob);
if (!error.isOk()) {
LOG(ERROR) << "delete_key failed: " << error.description();
return false;
}
if (error != km::ErrorCode::OK) {
LOG(ERROR) << "delete_key failed, code " << int32_t(km::ErrorCode(error));
return false;
}
return true;
}
bool Keymaster::upgradeKey(const std::string& oldKey, const km::AuthorizationSet& inParams,
std::string* newKey) {
auto oldKeyBlob = km::support::blob2hidlVec(oldKey);
km::ErrorCode km_error;
auto hidlCb = [&](km::ErrorCode ret, const hidl_vec<uint8_t>& upgradedKeyBlob) {
km_error = ret;
if (km_error != km::ErrorCode::OK) return;
if (newKey)
newKey->assign(reinterpret_cast<const char*>(&upgradedKeyBlob[0]),
upgradedKeyBlob.size());
};
auto error = mDevice->upgradeKey(oldKeyBlob, inParams.hidl_data(), hidlCb);
if (!error.isOk()) {
LOG(ERROR) << "upgrade_key failed: " << error.description();
return false;
}
if (km_error != km::ErrorCode::OK) {
LOG(ERROR) << "upgrade_key failed, code " << int32_t(km_error);
return false;
}
return true;
}
KeymasterOperation Keymaster::begin(km::KeyPurpose purpose, const std::string& key,
const km::AuthorizationSet& inParams,
const km::HardwareAuthToken& authToken,
km::AuthorizationSet* outParams) {
auto keyBlob = km::support::blob2hidlVec(key);
uint64_t mOpHandle;
km::ErrorCode km_error;
auto hidlCb = [&](km::ErrorCode ret, const hidl_vec<km::KeyParameter>& _outParams,
uint64_t operationHandle) {
km_error = ret;
if (km_error != km::ErrorCode::OK) return;
if (outParams) *outParams = _outParams;
mOpHandle = operationHandle;
};
auto error = mDevice->begin(purpose, keyBlob, inParams.hidl_data(), authToken, hidlCb);
if (!error.isOk()) {
LOG(ERROR) << "begin failed: " << error.description();
return KeymasterOperation(km::ErrorCode::UNKNOWN_ERROR);
}
if (km_error != km::ErrorCode::OK) {
LOG(ERROR) << "begin failed, code " << int32_t(km_error);
return KeymasterOperation(km_error);
}
return KeymasterOperation(mDevice.get(), mOpHandle);
}
bool Keymaster::isSecure() {
return mDevice->halVersion().securityLevel != km::SecurityLevel::SOFTWARE;
}
} // namespace vold
} // namespace android
using namespace ::android::vold;
int keymaster_compatibility_cryptfs_scrypt() {
Keymaster dev;
if (!dev) {
LOG(ERROR) << "Failed to initiate keymaster session";
return -1;
}
return dev.isSecure();
}
static bool write_string_to_buf(const std::string& towrite, uint8_t* buffer, uint32_t buffer_size,
uint32_t* out_size) {
if (!buffer || !out_size) {
LOG(ERROR) << "Missing target pointers";
return false;
}
*out_size = towrite.size();
if (buffer_size < towrite.size()) {
LOG(ERROR) << "Buffer too small " << buffer_size << " < " << towrite.size();
return false;
}
memset(buffer, '\0', buffer_size);
std::copy(towrite.begin(), towrite.end(), buffer);
return true;
}
static km::AuthorizationSet keyParams(uint32_t rsa_key_size, uint64_t rsa_exponent,
uint32_t ratelimit) {
return km::AuthorizationSetBuilder()
.RsaSigningKey(rsa_key_size, rsa_exponent)
.NoDigestOrPadding()
.Authorization(km::TAG_BLOB_USAGE_REQUIREMENTS, km::KeyBlobUsageRequirements::STANDALONE)
.Authorization(km::TAG_NO_AUTH_REQUIRED)
.Authorization(km::TAG_MIN_SECONDS_BETWEEN_OPS, ratelimit);
}
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) {
if (key_out_size) {
*key_out_size = 0;
}
Keymaster dev;
if (!dev) {
LOG(ERROR) << "Failed to initiate keymaster session";
return -1;
}
std::string key;
if (!dev.generateKey(keyParams(rsa_key_size, rsa_exponent, ratelimit), &key)) return -1;
if (!write_string_to_buf(key, key_buffer, key_buffer_size, key_out_size)) return -1;
return 0;
}
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) {
if (key_out_size) {
*key_out_size = 0;
}
Keymaster dev;
if (!dev) {
LOG(ERROR) << "Failed to initiate keymaster session";
return -1;
}
std::string old_key(reinterpret_cast<const char*>(key_blob), key_blob_size);
std::string new_key;
if (!dev.upgradeKey(old_key, keyParams(rsa_key_size, rsa_exponent, ratelimit), &new_key))
return -1;
if (!write_string_to_buf(new_key, key_buffer, key_buffer_size, key_out_size)) return -1;
return 0;
}
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) {
Keymaster dev;
if (!dev) {
LOG(ERROR) << "Failed to initiate keymaster session";
return KeymasterSignResult::error;
}
if (!key_blob || !object || !signature_buffer || !signature_buffer_size) {
LOG(ERROR) << __FILE__ << ":" << __LINE__ << ":Invalid argument";
return KeymasterSignResult::error;
}
km::AuthorizationSet outParams;
std::string key(reinterpret_cast<const char*>(key_blob), key_blob_size);
std::string input(reinterpret_cast<const char*>(object), object_size);
std::string output;
KeymasterOperation op;
auto paramBuilder = km::AuthorizationSetBuilder().NoDigestOrPadding();
while (true) {
op = dev.begin(km::KeyPurpose::SIGN, key, paramBuilder, km::HardwareAuthToken(), &outParams);
if (op.errorCode() == km::ErrorCode::KEY_RATE_LIMIT_EXCEEDED) {
sleep(ratelimit);
continue;
} else
break;
}
if (op.errorCode() == km::ErrorCode::KEY_REQUIRES_UPGRADE) {
LOG(ERROR) << "Keymaster key requires upgrade";
return KeymasterSignResult::upgrade;
}
if (op.errorCode() != km::ErrorCode::OK) {
LOG(ERROR) << "Error starting keymaster signature transaction: " << int32_t(op.errorCode());
return KeymasterSignResult::error;
}
if (!op.updateCompletely(input, &output)) {
LOG(ERROR) << "Error sending data to keymaster signature transaction: "
<< uint32_t(op.errorCode());
return KeymasterSignResult::error;
}
if (!op.finish(&output)) {
LOG(ERROR) << "Error finalizing keymaster signature transaction: "
<< int32_t(op.errorCode());
return KeymasterSignResult::error;
}
*signature_buffer = reinterpret_cast<uint8_t*>(malloc(output.size()));
if (*signature_buffer == nullptr) {
LOG(ERROR) << "Error allocation buffer for keymaster signature";
return KeymasterSignResult::error;
}
*signature_buffer_size = output.size();
std::copy(output.data(), output.data() + output.size(), *signature_buffer);
return KeymasterSignResult::ok;
}