Merge "Adding AIDL and functions for talking to RemoteProvisioner" am: e7f48b9926

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1650991

Change-Id: I44f222605ca947ce113b2d397035e541bcf59159

keystore/java/android/security/GenerateRkpKey.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+package android.security;
+
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.content.ServiceConnection;
+import android.os.IBinder;
+import android.os.RemoteException;
+
+/**
+ * GenerateKey is a helper class to handle interactions between Keystore and the RemoteProvisioner
+ * app. There are two cases where Keystore should use this class.
+ *
+ * (1) : An app generates a new attested key pair, so Keystore calls notifyKeyGenerated to let the
+ *       RemoteProvisioner app check if the state of the attestation key pool is getting low enough
+ *       to warrant provisioning more attestation certificates early.
+ *
+ * (2) : An app attempts to generate a new key pair, but the keystore service discovers it is out of
+ *       attestation key pairs and cannot provide one for the given application. Keystore can then
+ *       make a blocking call on notifyEmpty to allow the RemoteProvisioner app to get another
+ *       attestation certificate chain provisioned.
+ *
+ * In most cases, the proper usage of (1) should preclude the need for (2).
+ *
+ * @hide
+ */
+public class GenerateRkpKey {
+
+    private IGenerateRkpKeyService mBinder;
+    private Context mContext;
+
+    private ServiceConnection mConnection = new ServiceConnection() {
+        @Override
+        public void onServiceConnected(ComponentName className, IBinder service) {
+            mBinder = IGenerateRkpKeyService.Stub.asInterface(service);
+        }
+
+        @Override
+        public void onServiceDisconnected(ComponentName className) {
+            mBinder = null;
+        }
+    };
+
+    /**
+     * Constructor which takes a Context object.
+     */
+    public GenerateRkpKey(Context context) {
+        mContext = context;
+    }
+
+    /**
+     * Fulfills the use case of (2) described in the class documentation. Blocks until the
+     * RemoteProvisioner application can get new attestation keys signed by the server.
+     */
+    public void notifyEmpty(int securityLevel) throws RemoteException {
+        Intent intent = new Intent(IGenerateRkpKeyService.class.getName());
+        ComponentName comp = intent.resolveSystemService(mContext.getPackageManager(), 0);
+        intent.setComponent(comp);
+        if (comp == null || !mContext.bindService(intent, mConnection, Context.BIND_AUTO_CREATE)) {
+            throw new RemoteException("Failed to bind to GenerateKeyService");
+        }
+        if (mBinder != null) {
+            mBinder.generateKey(securityLevel);
+        }
+        mContext.unbindService(mConnection);
+    }
+
+    /**
+     * FUlfills the use case of (1) described in the class documentation. Non blocking call.
+     */
+    public void notifyKeyGenerated(int securityLevel) throws RemoteException {
+        Intent intent = new Intent(IGenerateRkpKeyService.class.getName());
+        ComponentName comp = intent.resolveSystemService(mContext.getPackageManager(), 0);
+        intent.setComponent(comp);
+        if (comp == null || !mContext.bindService(intent, mConnection, Context.BIND_AUTO_CREATE)) {
+            throw new RemoteException("Failed to bind to GenerateKeyService");
+        }
+        if (mBinder != null) {
+            mBinder.notifyKeyGenerated(securityLevel);
+        }
+        mContext.unbindService(mConnection);
+    }
+}

keystore/java/android/security/GenerateRkpKeyException.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+package android.security;
+
+/**
+ * Thrown on problems in attempting to attest to a key using a remotely provisioned key.
+ *
+ * @hide
+ */
+public class GenerateRkpKeyException extends Exception {
+
+    /**
+     * Constructs a new {@code GenerateRkpKeyException}.
+     */
+    public GenerateRkpKeyException() {
+    }
+}

keystore/java/android/security/IGenerateRkpKeyService.aidl

@@ -0,0 +1,36 @@
+/**
+ * Copyright (C) 2021 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.
+ */
+
+package android.security;
+
+/**
+ * Interface to allow the framework to notify the RemoteProvisioner app when keys are empty. This
+ * will be used if Keystore replies with an error code NO_KEYS_AVAILABLE in response to an
+ * attestation request. The framework can then synchronously call generateKey() to get more
+ * attestation keys generated and signed. Upon return, the caller can be certain an attestation key
+ * is available.
+ *
+ * @hide
+ */
+interface IGenerateRkpKeyService {
+    /**
+     * Ping the provisioner service to let it know an app generated a key. This may or may not have
+     * consumed a remotely provisioned attestation key, so the RemoteProvisioner app should check.
+     */
+    oneway void notifyKeyGenerated(in int securityLevel);
+    /** Ping the provisioner service to indicate there are no remaining attestation keys left. */
+    void generateKey(in int securityLevel);
+}

keystore/java/android/security/keystore2/AndroidKeyStoreKeyPairGeneratorSpi.java

@@ -24,6 +24,9 @@ import android.hardware.security.keymint.KeyPurpose;
 import android.hardware.security.keymint.SecurityLevel;
 import android.hardware.security.keymint.Tag;
 import android.os.Build;
+import android.os.RemoteException;
+import android.security.GenerateRkpKey;
+import android.security.GenerateRkpKeyException;
 import android.security.KeyPairGeneratorSpec;
 import android.security.KeyStore;
 import android.security.KeyStore2;
@@ -520,6 +523,18 @@ public abstract class AndroidKeyStoreKeyPairGeneratorSpi extends KeyPairGenerato
 
     @Override
     public KeyPair generateKeyPair() {
+        try {
+            return generateKeyPairHelper();
+        } catch (GenerateRkpKeyException e) {
+            try {
+                return generateKeyPairHelper();
+            } catch (GenerateRkpKeyException f) {
+                throw new ProviderException("Failed to provision new attestation keys.");
+            }
+        }
+    }
+
+    private KeyPair generateKeyPairHelper() throws GenerateRkpKeyException {
         if (mKeyStore == null || mSpec == null) {
             throw new IllegalStateException("Not initialized");
         }
@@ -557,13 +572,30 @@ public abstract class AndroidKeyStoreKeyPairGeneratorSpi extends KeyPairGenerato
             AndroidKeyStorePublicKey publicKey =
                     AndroidKeyStoreProvider.makeAndroidKeyStorePublicKeyFromKeyEntryResponse(
                             descriptor, metadata, iSecurityLevel, mKeymasterAlgorithm);
-
+            GenerateRkpKey keyGen = new GenerateRkpKey(KeyStore.getApplicationContext());
+            try {
+                if (mSpec.getAttestationChallenge() != null) {
+                    keyGen.notifyKeyGenerated(securityLevel);
+                }
+            } catch (RemoteException e) {
+                // This is not really an error state, and necessarily does not apply to non RKP
+                // systems or hybrid systems where RKP is not currently turned on.
+                Log.d(TAG, "Couldn't connect to the RemoteProvisioner backend.");
+            }
             success = true;
             return new KeyPair(publicKey, publicKey.getPrivateKey());
         } catch (android.security.KeyStoreException e) {
             switch(e.getErrorCode()) {
                 case KeymasterDefs.KM_ERROR_HARDWARE_TYPE_UNAVAILABLE:
                     throw new StrongBoxUnavailableException("Failed to generated key pair.", e);
+                case ResponseCode.OUT_OF_KEYS:
+                    GenerateRkpKey keyGen = new GenerateRkpKey(KeyStore.getApplicationContext());
+                    try {
+                        keyGen.notifyEmpty(securityLevel);
+                    } catch (RemoteException f) {
+                        throw new ProviderException("Failed to talk to RemoteProvisioner", f);
+                    }
+                    throw new GenerateRkpKeyException();
                 default:
                     ProviderException p = new ProviderException("Failed to generate key pair.", e);
                     if ((mSpec.getPurposes() & KeyProperties.PURPOSE_WRAP_KEY) != 0) {