1 /**
2  * Copyright (C) 2020 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.android.remoteprovisioner.service;
18 
19 import android.app.Service;
20 import android.content.Context;
21 import android.content.Intent;
22 import android.os.IBinder;
23 import android.os.RemoteException;
24 import android.os.ServiceManager;
25 import android.security.IGenerateRkpKeyService;
26 import android.security.remoteprovisioning.AttestationPoolStatus;
27 import android.security.remoteprovisioning.ImplInfo;
28 import android.security.remoteprovisioning.IRemoteProvisioning;
29 import android.util.Log;
30 
31 import com.android.remoteprovisioner.GeekResponse;
32 import com.android.remoteprovisioner.Provisioner;
33 import com.android.remoteprovisioner.ServerInterface;
34 import com.android.remoteprovisioner.SettingsManager;
35 
36 /**
37  * Provides the implementation for IGenerateKeyService.aidl
38  */
39 public class GenerateRkpKeyService extends Service {
40     private static final int KEY_GENERATION_PAUSE_MS = 1000;
41     private static final String SERVICE = "android.security.remoteprovisioning";
42     private static final String TAG = "RemoteProvisioningService";
43 
44     @Override
onCreate()45     public void onCreate() {
46         super.onCreate();
47     }
48 
49     @Override
onBind(Intent intent)50     public IBinder onBind(Intent intent) {
51         return mBinder;
52     }
53 
54     private final IGenerateRkpKeyService.Stub mBinder = new IGenerateRkpKeyService.Stub() {
55         @Override
56         public void generateKey(int securityLevel) {
57             try {
58                 Log.i(TAG, "generateKey ping for secLevel: " + securityLevel);
59                 IRemoteProvisioning binder =
60                         IRemoteProvisioning.Stub.asInterface(ServiceManager.getService(SERVICE));
61                 checkAndFillPool(binder, securityLevel);
62             } catch (RemoteException e) {
63                 Log.e(TAG, "Remote Exception: ", e);
64             }
65         }
66 
67         @Override
68         public void notifyKeyGenerated(int securityLevel) {
69             try {
70                 Log.i(TAG, "Notify key generated ping for secLevel: " + securityLevel);
71                 IRemoteProvisioning binder =
72                         IRemoteProvisioning.Stub.asInterface(ServiceManager.getService(SERVICE));
73                 checkAndFillPool(binder, securityLevel);
74             } catch (RemoteException e) {
75                 Log.e(TAG, "Remote Exception: ", e);
76             }
77         }
78 
79         private void checkAndFillPool(IRemoteProvisioning binder, int secLevel)
80                 throws RemoteException {
81             AttestationPoolStatus pool =
82                     binder.getPoolStatus(System.currentTimeMillis(), secLevel);
83             ImplInfo[] implInfos = binder.getImplementationInfo();
84             int curve = 0;
85             for (int i = 0; i < implInfos.length; i++) {
86                 if (implInfos[i].secLevel == secLevel) {
87                     curve = implInfos[i].supportedCurve;
88                     break;
89                 }
90             }
91             // If there are no unassigned keys, go ahead and provision some. If there are no
92             // attested keys at all on the system, this implies that it is a hybrid
93             // rkp/factory-provisioned system that has turned off RKP. In that case, do
94             // not provision.
95             if (pool.unassigned == 0 && pool.attested != 0) {
96                 Log.i(TAG, "All signed keys are currently in use, provisioning more.");
97                 Context context = getApplicationContext();
98                 int keysToProvision = SettingsManager.getExtraSignedKeysAvailable(context);
99                 int existingUnsignedKeys = pool.total - pool.attested;
100                 int keysToGenerate = keysToProvision - existingUnsignedKeys;
101                 try {
102                     for (int i = 0; i < keysToGenerate; i++) {
103                         binder.generateKeyPair(false /* isTestMode */, secLevel);
104                         Thread.sleep(KEY_GENERATION_PAUSE_MS);
105                     }
106                 } catch (InterruptedException e) {
107                     Log.i(TAG, "Thread interrupted", e);
108                 }
109                 GeekResponse resp = ServerInterface.fetchGeek(context);
110                 if (resp == null) {
111                     Log.e(TAG, "Server unavailable");
112                     return;
113                 }
114                 Provisioner.provisionCerts(keysToProvision, secLevel, resp.getGeekChain(curve),
115                                            resp.getChallenge(), binder, context);
116             }
117         }
118     };
119 }
120