C++ AIDL on-device GateKeeper / SharedSecret impl
Because Keystore2 always requires valid auth tokens for user keys, this
copies and extends the existing in-guest GateKeeper implementation to
negotiate a shared secret key with Keymint in order to generate a
session key for signing auth tokens.
This implementation also uses AIDL rather than HIDL to interact with the
framework. It's also packaged in an APEX.
The files are cobbled together from a few sources:
- SoftGateKeeper.h is based on hardware/interfaces/gatekeeper/1.0/software/SoftGateKeeper.h
- GateKeeper.{cpp,h} are based on device/google/cuttlefish/guest/hals/gatekeeper/remote/remote_gatekeeper.{cpp,h}
- SharedSecret.{cpp,h} are based on device/google/cuttlefish/guest/hals/keymint/remote/remote_shared_secret.{cpp,h}
- Apex files are based on device/google/cuttlefish/guest/hals/keymint/rust/
Keymint modifications to use BOOT_TIME are lifted from
https://android-review.git.corp.google.com/c/platform/hardware/interfaces/+/2856649/6..8/security/keymint/aidl/default/ta/clock.rs#38
Bug: 332376454
Change-Id: I81845d5e6370bdddb1a24d67437964e03a5fb243
Test: Run with rust-nonsecure keymint on Cuttlefish
diff --git a/gatekeeper/aidl/software/GateKeeper.cpp b/gatekeeper/aidl/software/GateKeeper.cpp
new file mode 100644
index 0000000..1fc3682
--- /dev/null
+++ b/gatekeeper/aidl/software/GateKeeper.cpp
@@ -0,0 +1,149 @@
+/*
+ * 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.
+ */
+#define LOG_TAG "android.hardware.gatekeeper-service.nonsecure"
+
+#include <endian.h>
+
+#include <android-base/logging.h>
+
+#include "GateKeeper.h"
+
+using ::gatekeeper::EnrollRequest;
+using ::gatekeeper::EnrollResponse;
+using ::gatekeeper::ERROR_NONE;
+using ::gatekeeper::ERROR_RETRY;
+using ::gatekeeper::SizedBuffer;
+using ::gatekeeper::VerifyRequest;
+using ::gatekeeper::VerifyResponse;
+
+namespace aidl::android::hardware::gatekeeper {
+
+SizedBuffer vec2sized_buffer(const std::vector<uint8_t>& vec) {
+ if (vec.size() == 0 || vec.size() > std::numeric_limits<uint32_t>::max()) {
+ return {};
+ }
+ auto unused = new uint8_t[vec.size()];
+ std::copy(vec.begin(), vec.end(), unused);
+ return {unused, static_cast<uint32_t>(vec.size())};
+}
+
+void sizedBuffer2AidlHWToken(SizedBuffer& buffer,
+ android::hardware::security::keymint::HardwareAuthToken* aidlToken) {
+ const hw_auth_token_t* authToken =
+ reinterpret_cast<const hw_auth_token_t*>(buffer.Data<uint8_t>());
+ aidlToken->challenge = authToken->challenge;
+ aidlToken->userId = authToken->user_id;
+ aidlToken->authenticatorId = authToken->authenticator_id;
+ // these are in network order: translate to host
+ aidlToken->authenticatorType =
+ static_cast<android::hardware::security::keymint::HardwareAuthenticatorType>(
+ be32toh(authToken->authenticator_type));
+ aidlToken->timestamp.milliSeconds = be64toh(authToken->timestamp);
+ aidlToken->mac.insert(aidlToken->mac.begin(), std::begin(authToken->hmac),
+ std::end(authToken->hmac));
+}
+
+SoftGateKeeperDevice::SoftGateKeeperDevice(::gatekeeper::SoftGateKeeper& impl) : impl_(impl) {}
+
+::ndk::ScopedAStatus SoftGateKeeperDevice::enroll(int32_t uid,
+ const std::vector<uint8_t>& currentPasswordHandle,
+ const std::vector<uint8_t>& currentPassword,
+ const std::vector<uint8_t>& desiredPassword,
+ GatekeeperEnrollResponse* rsp) {
+ if (desiredPassword.size() == 0) {
+ LOG(ERROR) << "Desired password size is 0";
+ return ndk::ScopedAStatus(AStatus_fromServiceSpecificError(ERROR_GENERAL_FAILURE));
+ }
+
+ if (currentPasswordHandle.size() > 0) {
+ if (currentPasswordHandle.size() != sizeof(::gatekeeper::password_handle_t)) {
+ LOG(ERROR) << "Password handle has wrong length";
+ return ndk::ScopedAStatus(AStatus_fromServiceSpecificError(ERROR_GENERAL_FAILURE));
+ }
+ }
+
+ EnrollRequest request(uid, vec2sized_buffer(currentPasswordHandle),
+ vec2sized_buffer(desiredPassword), vec2sized_buffer(currentPassword));
+ EnrollResponse response;
+ impl_.Enroll(request, &response);
+ if (response.error == ERROR_RETRY) {
+ LOG(ERROR) << "Enroll response has a retry error";
+ *rsp = {ERROR_RETRY_TIMEOUT, static_cast<int32_t>(response.retry_timeout), 0, {}};
+ return ndk::ScopedAStatus::ok();
+ } else if (response.error != ERROR_NONE) {
+ LOG(ERROR) << "Enroll response has an error: " << response.error;
+ return ndk::ScopedAStatus(AStatus_fromServiceSpecificError(ERROR_GENERAL_FAILURE));
+ } else {
+ const ::gatekeeper::password_handle_t* password_handle =
+ response.enrolled_password_handle.Data<::gatekeeper::password_handle_t>();
+ *rsp = {STATUS_OK,
+ 0,
+ static_cast<int64_t>(password_handle->user_id),
+ {response.enrolled_password_handle.Data<uint8_t>(),
+ (response.enrolled_password_handle.Data<uint8_t>() +
+ response.enrolled_password_handle.size())}};
+ }
+ return ndk::ScopedAStatus::ok();
+}
+
+::ndk::ScopedAStatus SoftGateKeeperDevice::verify(
+ int32_t uid, int64_t challenge, const std::vector<uint8_t>& enrolledPasswordHandle,
+ const std::vector<uint8_t>& providedPassword, GatekeeperVerifyResponse* rsp) {
+ if (enrolledPasswordHandle.size() == 0) {
+ LOG(ERROR) << "Enrolled password size is 0";
+ return ndk::ScopedAStatus(AStatus_fromServiceSpecificError(ERROR_GENERAL_FAILURE));
+ }
+
+ if (enrolledPasswordHandle.size() > 0) {
+ if (enrolledPasswordHandle.size() != sizeof(::gatekeeper::password_handle_t)) {
+ LOG(ERROR) << "Password handle has wrong length";
+ return ndk::ScopedAStatus(AStatus_fromServiceSpecificError(ERROR_GENERAL_FAILURE));
+ }
+ }
+
+ VerifyRequest request(uid, challenge, vec2sized_buffer(enrolledPasswordHandle),
+ vec2sized_buffer(providedPassword));
+ VerifyResponse response;
+ impl_.Verify(request, &response);
+
+ if (response.error == ERROR_RETRY) {
+ LOG(ERROR) << "Verify request response gave retry error";
+ *rsp = {ERROR_RETRY_TIMEOUT, static_cast<int32_t>(response.retry_timeout), {}};
+ return ndk::ScopedAStatus::ok();
+ } else if (response.error != ERROR_NONE) {
+ LOG(ERROR) << "Verify request response gave error: " << response.error;
+ return ndk::ScopedAStatus(AStatus_fromServiceSpecificError(ERROR_GENERAL_FAILURE));
+ } else {
+ // On Success, return GatekeeperVerifyResponse with Success Status, timeout{0} and
+ // valid HardwareAuthToken.
+ *rsp = {response.request_reenroll ? STATUS_REENROLL : STATUS_OK, 0, {}};
+ // Convert the hw_auth_token_t to HardwareAuthToken in the response.
+ sizedBuffer2AidlHWToken(response.auth_token, &rsp->hardwareAuthToken);
+ }
+ return ndk::ScopedAStatus::ok();
+}
+
+::ndk::ScopedAStatus SoftGateKeeperDevice::deleteUser(int32_t /*uid*/) {
+ LOG(ERROR) << "deleteUser is unimplemented";
+ return ndk::ScopedAStatus(AStatus_fromServiceSpecificError(ERROR_NOT_IMPLEMENTED));
+}
+
+::ndk::ScopedAStatus SoftGateKeeperDevice::deleteAllUsers() {
+ LOG(ERROR) << "deleteAllUsers is unimplemented";
+ return ndk::ScopedAStatus(AStatus_fromServiceSpecificError(ERROR_NOT_IMPLEMENTED));
+}
+
+} // namespace aidl::android::hardware::gatekeeper