1page.title=Enhancing Security with Device Management Policies 2parent.title=Developing for Enterprise 3parent.link=index.html 4@jd:body 5 6 7<div id="tb-wrapper"> 8<div id="tb"> 9 10<h2>This lesson teaches you to</h2> 11<ol> 12 <li><a href="#DeclarePolicy">Define and Declare Your Policy</a></li> 13 <li><a href="#CreateDeviceAdminReceiver">Create a Device Administration Receiver</a></li> 14 <li><a href="#ActivateDeviceAdmin">Activate the Device Administrator</a></li> 15 <li><a href="#ImplementDevicePolicyController">Implement the Device Policy Controller</a></li> 16</ol> 17 18<!-- related docs (NOT javadocs) --> 19<h2>You should also read</h2> 20<ul> 21 <li><a href="{@docRoot}guide/topics/admin/device-admin.html">Device Administration</a></li> 22</ul> 23 24<h2>Try it out</h2> 25 26<div class="download-box"> 27 <a href="{@docRoot}shareables/training/DeviceManagement.zip" 28class="button">Download the sample</a> 29 <p class="filename">DeviceManagement.zip</p> 30</div> 31 32</div> 33</div> 34 35 36<p>Since Android 2.2 (API level 8), the Android platform offers system-level device management 37capabilities through the Device Administration APIs.</p> 38 39<p>In this lesson, you will learn how to create a security-aware application that manages access to 40its content by enforcing device management policies. Specifically, the application can be configured 41such that it ensures a screen-lock password of sufficient strength is set up before displaying 42restricted content to the user.</p> 43 44 45<h2 id="DeclarePolicy">Define and Declare Your Policy</h2> 46 47<p>First, you need to define the kinds of policy to support at the functional level. Policies may 48cover screen-lock password strength, expiration timeout, encryption, etc.</p> 49 50<p>You must declare the selected policy set, which will be enforced by the application, in the 51<code>res/xml/device_admin.xml</code> file. The Android manifest should also reference the 52declared policy set.</p> 53 54<p>Each declared policy corresponds to some number of related device policy methods in {@link 55android.app.admin.DevicePolicyManager} (defining minimum password length and minimum number of 56uppercase characters are two examples). If an application attempts to invoke methods whose 57corresponding policy is not declared in the XML, this will result in a {@link 58java.lang.SecurityException} at runtime. Other permissions, 59such as <code>force-lock</code>, are available if the application intends to manage 60other kinds of policy. As you'll see later, as part of the device administrator activation process, 61the list of declared policies will be presented to the user on a system screen.</p> 62 63<p>The following snippet declares the limit password policy in <code>res/xml/device_admin.xml</code>:</p> 64 65<pre> 66<device-admin xmlns:android="http://schemas.android.com/apk/res/android"> 67 <uses-policies> 68 <limit-password /> 69 </uses-policies> 70</device-admin> 71</pre> 72 73<p>Policy declaration XML referenced in Android manifest:</p> 74 75<pre> 76<receiver android:name=".Policy$PolicyAdmin" 77 android:permission="android.permission.BIND_DEVICE_ADMIN"> 78 <strong><meta-data android:name="android.app.device_admin" 79 android:resource="@xml/device_admin" /></strong> 80 <intent-filter> 81 <action android:name="android.app.action.DEVICE_ADMIN_ENABLED" /> 82 </intent-filter> 83</receiver> 84</pre> 85 86 87<h2 id="CreateDeviceAdminReceiver">Create a Device Administration Receiver</h2> 88 89<p>Create a Device Administration broadcast receiver, which gets notified of events related to the policies you’ve declared to support. An application can selectively override callback methods.</p> 90 91<p>In the sample application, Device Admin, when the device administrator is deactivated by the 92user, the configured policy is erased from the shared preference. You should consider implementing 93business logic that is relevant to your use case. For example, the application might take some 94actions to mitigate security risk by implementing some combination of deleting sensitive data on the 95device, disabling remote synchronization, alerting an administrator, etc.</p> 96 97<p>For the broadcast receiver to work, be sure to register it in the Android manifest as illustrated in the above snippet.</p> 98 99<pre> 100public static class PolicyAdmin extends DeviceAdminReceiver { 101 102 @Override 103 public void onDisabled(Context context, Intent intent) { 104 // Called when the app is about to be deactivated as a device administrator. 105 // Deletes previously stored password policy. 106 super.onDisabled(context, intent); 107 SharedPreferences prefs = context.getSharedPreferences(APP_PREF, Activity.MODE_PRIVATE); 108 prefs.edit().clear().commit(); 109 } 110} 111</pre> 112 113 114<h2 id="ActivateDeviceAdmin">Activate the Device Administrator</h2> 115 116<p>Before enforcing any policies, the user needs to manually activate the application as a device 117administrator. The snippet below illustrates how to trigger the settings activity in which the 118user can activate your application. It is good practice to include the explanatory text to highlight 119to users why the application is requesting to be a device administrator, by specifying the 120{@link android.app.admin.DevicePolicyManager#EXTRA_ADD_EXPLANATION} extra in the intent.</p> 121 122<div class="figure" style="width:220px"> 123<img src="/images/training/device-mgmt-activate-device-admin.png" /> 124<p class="img-caption"><strong>Figure 1.</strong> The user activation screen in which you can 125provide a description of your device policies.</p> 126</div> 127 128<pre> 129if (!mPolicy.isAdminActive()) { 130 131 Intent activateDeviceAdminIntent = 132 new Intent(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN); 133 134 activateDeviceAdminIntent.putExtra( 135 DevicePolicyManager.EXTRA_DEVICE_ADMIN, 136 mPolicy.getPolicyAdmin()); 137 138 // It is good practice to include the optional explanation text to 139 // explain to user why the application is requesting to be a device 140 // administrator. The system will display this message on the activation 141 // screen. 142 activateDeviceAdminIntent.putExtra( 143 DevicePolicyManager.EXTRA_ADD_EXPLANATION, 144 getResources().getString(R.string.device_admin_activation_message)); 145 146 startActivityForResult(activateDeviceAdminIntent, 147 REQ_ACTIVATE_DEVICE_ADMIN); 148} 149</pre> 150 151<p>If the user chooses "Activate," the application becomes a device administrator and can begin 152configuring and enforcing the policy.</p> 153 154<p>The application also needs to be prepared to handle set back situations where the user abandons 155the activation process by hitting the Cancel button, the Back key, or the Home key. Therefore, 156{@link android.app.Activity#onResume onResume()} in the Policy Set Up Activity needs to have logic 157to reevaluate the condition and present the Device Administrator Activation option to the user if 158needed.</p> 159 160 161<h2 id="ImplementDevicePolicyController">Implement the Device Policy Controller</h2> 162 163<p>After the device administrator is activated successfully, the application then configures Device 164Policy Manager with the requested policy. Keep in mind that new policies are being added to 165Android with each release. It is appropriate to perform version checks in your application if using 166new policies while supporting older versions of the platform. For example, the Password Minimum 167Upper Case policy is only available with API level 11 (Honeycomb) and above. The following code 168demonstrates how you can check the version at runtime.</p> 169 170<pre> 171DevicePolicyManager mDPM = (DevicePolicyManager) 172 context.getSystemService(Context.DEVICE_POLICY_SERVICE); 173ComponentName mPolicyAdmin = new ComponentName(context, PolicyAdmin.class); 174... 175mDPM.setPasswordQuality(mPolicyAdmin, PASSWORD_QUALITY_VALUES[mPasswordQuality]); 176mDPM.setPasswordMinimumLength(mPolicyAdmin, mPasswordLength); 177if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { 178 mDPM.setPasswordMinimumUpperCase(mPolicyAdmin, mPasswordMinUpperCase); 179} 180</pre> 181 182<p>At this point, the application is able to enforce the policy. While the application has no access 183to the actual screen-lock password used, through the Device Policy Manager API it can determine 184whether the existing password satisfies the required policy. If it turns out that the existing 185screen-lock password is not sufficient, the device administration API does not automatically take 186corrective action. It is the application’s responsibility to explicitly launch the system 187password-change screen in the Settings app. For example:</p> 188 189<pre> 190if (!mDPM.isActivePasswordSufficient()) { 191 ... 192 // Triggers password change screen in Settings. 193 Intent intent = 194 new Intent(DevicePolicyManager.ACTION_SET_NEW_PASSWORD); 195 startActivity(intent); 196} 197</pre> 198 199<p>Normally, the user can select from one of the available lock mechanisms, such as None, Pattern, 200PIN (numeric), or Password (alphanumeric). When a password policy is configured, those password 201types that are weaker than those defined in the policy are disabled. For example, if the 202“Numeric” password quality is configured, the user can select either PIN (numeric) or Password 203(alphanumeric) password only.</p> 204 205<p>Once the device is properly secured by setting up a proper screen-lock password, the application 206allows access to the secured content.</p> 207 208<pre> 209if (!mDPM.isAdminActive(..)) { 210 // Activates device administrator. 211 ... 212} else if (!mDPM.isActivePasswordSufficient()) { 213 // Launches password set-up screen in Settings. 214 ... 215} else { 216 // Grants access to secure content. 217 ... 218 startActivity(new Intent(context, SecureActivity.class)); 219} 220</pre> 221
