Introduce android:lockTaskMode

The ability for tasks to be started in locktask mode or pinned is
dependent on the value of android:lockTaskMode for the root activity
of the task.

For bug 19995702

Change-Id: I514a144a3a0ff7dbdd4987da5361b94bdfe9a437
diff --git a/api/current.txt b/api/current.txt
index 7575a07..cf3f489 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -815,6 +815,7 @@
     field public static final int listSeparatorTextViewStyle = 16843272; // 0x1010208
     field public static final int listViewStyle = 16842868; // 0x1010074
     field public static final int listViewWhiteStyle = 16842869; // 0x1010075
+    field public static final int lockTaskMode = 16844013; // 0x10104ed
     field public static final int logo = 16843454; // 0x10102be
     field public static final int longClickable = 16842982; // 0x10100e6
     field public static final int loopViews = 16843527; // 0x1010307
diff --git a/api/system-current.txt b/api/system-current.txt
index fb44b61..15c00f4 100644
--- a/api/system-current.txt
+++ b/api/system-current.txt
@@ -888,6 +888,7 @@
     field public static final int listSeparatorTextViewStyle = 16843272; // 0x1010208
     field public static final int listViewStyle = 16842868; // 0x1010074
     field public static final int listViewWhiteStyle = 16842869; // 0x1010075
+    field public static final int lockTaskMode = 16844013; // 0x10104ed
     field public static final int logo = 16843454; // 0x10102be
     field public static final int longClickable = 16842982; // 0x10100e6
     field public static final int loopViews = 16843527; // 0x1010307
diff --git a/core/java/android/app/Activity.java b/core/java/android/app/Activity.java
index 6cf6481..4ccde1c 100644
--- a/core/java/android/app/Activity.java
+++ b/core/java/android/app/Activity.java
@@ -6434,18 +6434,22 @@
      * Request to put this Activity in a mode where the user is locked to the
      * current task.
      *
-     * This will prevent the user from launching other apps, going to settings,
-     * or reaching the home screen.
+     * This will prevent the user from launching other apps, going to settings, or reaching the
+     * home screen. This does not include those apps whose {@link android.R.attr#lockTaskMode}
+     * values permit launching while locked.
      *
-     * If {@link DevicePolicyManager#isLockTaskPermitted(String)} returns true
-     * for this component then the app will go directly into Lock Task mode.  The user
-     * will not be able to exit this mode until {@link Activity#stopLockTask()} is called.
+     * If {@link DevicePolicyManager#isLockTaskPermitted(String)} returns true or
+     * lockTaskMode=lockTaskModeAlways for this component then the app will go directly into
+     * Lock Task mode. The user will not be able to exit this mode until
+     * {@link Activity#stopLockTask()} is called.
      *
      * If {@link DevicePolicyManager#isLockTaskPermitted(String)} returns false
      * then the system will prompt the user with a dialog requesting permission to enter
      * this mode.  When entered through this method the user can exit at any time through
      * an action described by the request dialog.  Calling stopLockTask will also exit the
      * mode.
+     *
+     * @see android.R.attr#lockTaskMode
      */
     public void startLockTask() {
         try {
@@ -6462,6 +6466,14 @@
      * startLockTask previously.
      *
      * This will allow the user to exit this app and move onto other activities.
+     * <p>Note: This method should only be called when the activity is user-facing. That is,
+     * between onResume() and onPause().
+     * <p>Note: If there are other tasks below this one that are also locked then calling this
+     * method will immediately finish this task and resume the previous locked one, remaining in
+     * lockTask mode.
+     *
+     * @see android.R.attr#lockTaskMode
+     * @see ActivityManager#getLockTaskModeState()
      */
     public void stopLockTask() {
         try {
diff --git a/core/java/android/content/pm/ActivityInfo.java b/core/java/android/content/pm/ActivityInfo.java
index 4723c0d..8d82aa2 100644
--- a/core/java/android/content/pm/ActivityInfo.java
+++ b/core/java/android/content/pm/ActivityInfo.java
@@ -609,7 +609,7 @@
      * attribute.
      */
     public int configChanges;
-    
+
     /**
      * The desired soft input mode for this activity's main window.
      * Set from the {@link android.R.attr#windowSoftInputMode} attribute
@@ -648,6 +648,37 @@
      */
     public boolean resizeable;
 
+    /** @hide */
+    public static final int LOCK_TASK_LAUNCH_MODE_DEFAULT = 0;
+    /** @hide */
+    public static final int LOCK_TASK_LAUNCH_MODE_NEVER = 1;
+    /** @hide */
+    public static final int LOCK_TASK_LAUNCH_MODE_ALWAYS = 2;
+    /** @hide */
+    public static final int LOCK_TASK_LAUNCH_MODE_IF_WHITELISTED = 3;
+
+    /** @hide */
+    public static final String lockTaskLaunchModeToString(int lockTaskLaunchMode) {
+        switch (lockTaskLaunchMode) {
+            case LOCK_TASK_LAUNCH_MODE_DEFAULT:
+                return "LOCK_TASK_LAUNCH_MODE_DEFAULT";
+            case LOCK_TASK_LAUNCH_MODE_NEVER:
+                return "LOCK_TASK_LAUNCH_MODE_NEVER";
+            case LOCK_TASK_LAUNCH_MODE_ALWAYS:
+                return "LOCK_TASK_LAUNCH_MODE_ALWAYS";
+            case LOCK_TASK_LAUNCH_MODE_IF_WHITELISTED:
+                return "LOCK_TASK_LAUNCH_MODE_IF_WHITELISTED";
+            default:
+                return "unknown=" + lockTaskLaunchMode;
+        }
+    }
+    /**
+     * Value indicating if the activity is to be locked at startup. Takes on the values from
+     * {@link android.R.attr#lockTaskMode}.
+     * @hide
+     */
+    public int lockTaskLaunchMode;
+
     public ActivityInfo() {
     }
 
@@ -665,13 +696,15 @@
         uiOptions = orig.uiOptions;
         parentActivityName = orig.parentActivityName;
         maxRecents = orig.maxRecents;
+        resizeable = orig.resizeable;
+        lockTaskLaunchMode = orig.lockTaskLaunchMode;
     }
-    
+
     /**
      * Return the theme resource identifier to use for this activity.  If
      * the activity defines a theme, that is used; else, the application
      * theme is used.
-     * 
+     *
      * @return The theme associated with this activity.
      */
     public final int getThemeResource() {
@@ -709,7 +742,8 @@
         if (uiOptions != 0) {
             pw.println(prefix + " uiOptions=0x" + Integer.toHexString(uiOptions));
         }
-        pw.println(prefix + "resizeable=" + resizeable);
+        pw.println(prefix + "resizeable=" + resizeable + " lockTaskLaunchMode="
+                + lockTaskLaunchModeToString(lockTaskLaunchMode));
         super.dumpBack(pw, prefix);
     }
     
@@ -739,6 +773,7 @@
         dest.writeInt(persistableMode);
         dest.writeInt(maxRecents);
         dest.writeInt(resizeable ? 1 : 0);
+        dest.writeInt(lockTaskLaunchMode);
     }
 
     public static final Parcelable.Creator<ActivityInfo> CREATOR
@@ -767,5 +802,6 @@
         persistableMode = source.readInt();
         maxRecents = source.readInt();
         resizeable = (source.readInt() == 1);
+        lockTaskLaunchMode = source.readInt();
     }
 }
diff --git a/core/java/android/content/pm/PackageParser.java b/core/java/android/content/pm/PackageParser.java
index 7464cab..40f4e8f 100644
--- a/core/java/android/content/pm/PackageParser.java
+++ b/core/java/android/content/pm/PackageParser.java
@@ -3159,6 +3159,9 @@
                         R.styleable.AndroidManifestActivity_screenOrientation,
                         ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);
             }
+
+            a.info.lockTaskLaunchMode =
+                    sa.getInt(R.styleable.AndroidManifestActivity_lockTaskMode, 0);
         } else {
             a.info.launchMode = ActivityInfo.LAUNCH_MULTIPLE;
             a.info.configChanges = 0;
diff --git a/core/res/res/values/attrs_manifest.xml b/core/res/res/values/attrs_manifest.xml
index 5ffe57e..31c221b 100644
--- a/core/res/res/values/attrs_manifest.xml
+++ b/core/res/res/values/attrs_manifest.xml
@@ -1038,6 +1038,47 @@
          activity. -->
     <attr name="resizeableActivity" format="boolean" />
 
+    <!-- This value indicates how tasks rooted at this activity will behave in lockTask mode.
+         While in lockTask mode the system will not launch non-permitted tasks until
+         lockTask mode is disabled.
+         <p>While in lockTask mode with multiple permitted tasks running, each launched task is
+         permitted to finish, transitioning to the previous locked task, until there is only one
+         task remaining. At that point the last task running is not permitted to finish. -->
+    <attr name="lockTaskMode">
+        <!-- This is the default value. Tasks will not launch into lockTask mode but can be
+             placed there by calling {@link android.app.Activity#startLockTask}. If a task with
+             this mode has been whitelisted using {@link
+             android.app.admin.DevicePolicyManager#setLockTaskPackages} then calling startLockTask
+             will enter lockTask mode immediately, otherwise the user will be presented with a
+             dialog to approve entering lockTask mode.
+             <p>If the system is already in lockTask mode when a new task rooted at this activity
+             is launched that task will or will not start depending on whether the package of this
+             activity has been whitelisted.
+             <p>Tasks rooted at this activity can only exit lockTask mode using stopLockTask(). -->
+        <enum name="lockTaskModeDefault" value="0"/>
+        <!-- Tasks will not launch into lockTask mode and cannot be placed there using
+             {@link android.app.Activity#startLockTask} or be pinned from the Overview screen.
+             If the system is already in lockTask mode when a new task rooted at this activity is
+             launched that task will not be started.
+             <p>Note: This mode is only available to system and privileged applications.
+             Non-privileged apps with this value will be treated as lockTaskModeDefault.
+             -->
+        <enum name="lockTaskModeNever" value="1"/>
+        <!-- Tasks rooted at this activity will always launch into lockTask mode. If the system is
+             already in lockTask mode when this task is launched then the new task will be launched
+             on top of the current task. Tasks launched in this mode are capable of exiting
+             lockTask mode using finish(), whereas tasks entering lockTask mode using
+             startLockTask() must use stopLockTask() to exit.
+             <p>Note: This mode is only available to system and privileged applications.
+             Non-privileged apps with this value will be treated as lockTaskModeDefault.
+             -->
+        <enum name="lockTaskModeAlways" value="2"/>
+        <!-- If the DevicePolicyManager (DPM) authorizes this package ({@link
+             android.app.admin.DevicePolicyManager#setLockTaskPackages}) then this mode is
+             identical to lockTaskModeAlways. If the DPM does not authorize this package then this
+             mode is identical to lockTaskModeDefault. -->
+        <enum name="lockTaskModeIfWhitelisted" value="3"/>
+    </attr>
     <!-- When set installer will extract native libraries. If set to false
          libraries in the apk must be stored and page-aligned.  -->
     <attr name="extractNativeLibs" format="boolean"/>
@@ -1684,7 +1725,7 @@
          {@link android.app.Activity} class that is available
          as part of the package's application components, implementing
          a part of the application's user interface.
-         
+
          <p>Zero or more {@link #AndroidManifestIntentFilter intent-filter}
          tags can be included inside of an activity, to specify the Intents
          that it can handle.  If none are specified, the activity can
@@ -1746,12 +1787,13 @@
         <attr name="relinquishTaskIdentity" />
         <attr name="resumeWhilePausing" />
         <attr name="resizeableActivity" />
+        <attr name="lockTaskMode" />
     </declare-styleable>
-    
+
     <!-- The <code>activity-alias</code> tag declares a new
          name for an existing {@link #AndroidManifestActivity activity}
          tag.
-         
+
          <p>Zero or more {@link #AndroidManifestIntentFilter intent-filter}
          tags can be included inside of an activity-alias, to specify the Intents
          that it can handle.  If none are specified, the activity can
@@ -1769,7 +1811,7 @@
              must be in the same manifest as the alias, and have been defined
              in that manifest before the alias here.  This must use a Java-style
              naming convention to ensure the name is unique, for example
-             "com.mycompany.MyName". -->  
+             "com.mycompany.MyName". -->
         <attr name="targetActivity" format="string" />
         <attr name="label" />
         <attr name="description" />
@@ -1785,7 +1827,7 @@
         <attr name="exported" />
         <attr name="parentActivityName" />
     </declare-styleable>
-    
+
     <!-- The <code>meta-data</code> tag is used to attach additional
          arbitrary data to an application component.  The data can later
          be retrieved programmatically from the
diff --git a/core/res/res/values/public.xml b/core/res/res/values/public.xml
index c2f2c6d..f9d43bd 100644
--- a/core/res/res/values/public.xml
+++ b/core/res/res/values/public.xml
@@ -2653,6 +2653,7 @@
   <public type="attr" name="colorBackgroundFloating" />
   <public type="attr" name="extractNativeLibs" />
   <public type="attr" name="usesCleartextTraffic" />
+  <public type="attr" name="lockTaskMode" />
 
   <!--IntentFilter auto verification -->
   <public type="attr" name="autoVerify" />
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index b606353..f25808b 100644
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -26,10 +26,14 @@
 import static com.android.internal.util.XmlUtils.writeBooleanAttribute;
 import static com.android.internal.util.XmlUtils.writeIntAttribute;
 import static com.android.internal.util.XmlUtils.writeLongAttribute;
-import static com.android.server.am.ActivityStackSupervisor.HOME_STACK_ID;
-import static com.android.server.am.ActivityManagerDebugConfig.*;
-import static com.android.server.am.TaskRecord.INVALID_TASK_ID;
 import static com.android.server.Watchdog.NATIVE_STACKS_OF_INTEREST;
+import static com.android.server.am.ActivityManagerDebugConfig.*;
+import static com.android.server.am.ActivityStackSupervisor.HOME_STACK_ID;
+import static com.android.server.am.TaskRecord.INVALID_TASK_ID;
+import static com.android.server.am.TaskRecord.LOCK_TASK_AUTH_DONT_LOCK;
+import static com.android.server.am.TaskRecord.LOCK_TASK_AUTH_LAUNCHABLE;
+import static com.android.server.am.TaskRecord.LOCK_TASK_AUTH_PINNABLE;
+import static com.android.server.am.TaskRecord.LOCK_TASK_AUTH_WHITELISTED;
 import static org.xmlpull.v1.XmlPullParser.END_DOCUMENT;
 import static org.xmlpull.v1.XmlPullParser.START_TAG;
 
@@ -3982,13 +3986,13 @@
             if (rootR == null) {
                 Slog.w(TAG, "Finishing task with all activities already finished");
             }
-            // Do not allow task to finish in Lock Task mode.
-            if (tr == mStackSupervisor.mLockTaskModeTask) {
-                if (rootR == r) {
-                    Slog.i(TAG, "Not finishing task in lock task mode");
-                    mStackSupervisor.showLockTaskToast();
-                    return false;
-                }
+            // Do not allow task to finish if last task in lockTask mode. Launchable apps can
+            // finish themselves.
+            if (tr.mLockTaskAuth != LOCK_TASK_AUTH_LAUNCHABLE && rootR == r &&
+                    mStackSupervisor.isLastLockedTask(tr)) {
+                Slog.i(TAG, "Not finishing task in lock task mode");
+                mStackSupervisor.showLockTaskToast();
+                return false;
             }
             if (mController != null) {
                 // Find the first activity that is not finishing.
@@ -4142,20 +4146,18 @@
             final long origId = Binder.clearCallingIdentity();
             try {
                 ActivityRecord r = ActivityRecord.isInStackLocked(token);
+                if (r == null) {
+                    return false;
+                }
 
-                ActivityRecord rootR = r.task.getRootActivity();
-                // Do not allow task to finish in Lock Task mode.
-                if (r.task == mStackSupervisor.mLockTaskModeTask) {
-                    if (rootR == r) {
-                        mStackSupervisor.showLockTaskToast();
-                        return false;
-                    }
+                // Do not allow the last non-launchable task to finish in Lock Task mode.
+                final TaskRecord task = r.task;
+                if (task.mLockTaskAuth != LOCK_TASK_AUTH_LAUNCHABLE &&
+                        mStackSupervisor.isLastLockedTask(task) && task.getRootActivity() == r) {
+                    mStackSupervisor.showLockTaskToast();
+                    return false;
                 }
-                boolean res = false;
-                if (r != null) {
-                    res = r.task.stack.finishActivityAffinityLocked(r);
-                }
-                return res;
+                return task.stack.finishActivityAffinityLocked(r);
             } finally {
                 Binder.restoreCallingIdentity(origId);
             }
@@ -8336,9 +8338,9 @@
             final long origId = Binder.clearCallingIdentity();
             try {
                 int taskId = ActivityRecord.getTaskForActivityLocked(token, !nonRoot);
-                if (taskId >= 0) {
-                    if ((mStackSupervisor.mLockTaskModeTask != null)
-                            && (mStackSupervisor.mLockTaskModeTask.taskId == taskId)) {
+                final TaskRecord task = mRecentTasks.taskForIdLocked(taskId);
+                if (task != null) {
+                    if (mStackSupervisor.isLockedTask(task)) {
                         mStackSupervisor.showLockTaskToast();
                         return false;
                     }
@@ -8520,47 +8522,45 @@
 
     @Override
     public void updateLockTaskPackages(int userId, String[] packages) {
-        if (Binder.getCallingUid() != Process.SYSTEM_UID) {
+        final int callingUid = Binder.getCallingUid();
+        if (callingUid != 0 && callingUid != Process.SYSTEM_UID) {
             throw new SecurityException("updateLockTaskPackage called from non-system process");
         }
         synchronized (this) {
             mLockTaskPackages.put(userId, packages);
+            mStackSupervisor.onLockTaskPackagesUpdatedLocked();
         }
     }
 
-    private boolean isLockTaskAuthorizedLocked(String pkg) {
-        String[] packages = mLockTaskPackages.get(mCurrentUserId);
-        if (packages == null) {
-            return false;
-        }
-        for (int i = packages.length - 1; i >= 0; --i) {
-            if (pkg.equals(packages[i])) {
-                return true;
-            }
-        }
-        return false;
-    }
 
     void startLockTaskModeLocked(TaskRecord task) {
-        final String pkg = task.intent.getComponent().getPackageName();
+        if (task.mLockTaskAuth == LOCK_TASK_AUTH_DONT_LOCK) {
+            return;
+        }
+
         // isSystemInitiated is used to distinguish between locked and pinned mode, as pinned mode
         // is initiated by system after the pinning request was shown and locked mode is initiated
         // by an authorized app directly
-        boolean isSystemInitiated = Binder.getCallingUid() == Process.SYSTEM_UID;
+        final int callingUid = Binder.getCallingUid();
+        boolean isSystemInitiated = callingUid == Process.SYSTEM_UID;
         long ident = Binder.clearCallingIdentity();
         try {
-            if (!isSystemInitiated && !isLockTaskAuthorizedLocked(pkg)) {
-                StatusBarManagerInternal statusBarManager =
-                        LocalServices.getService(StatusBarManagerInternal.class);
-                if (statusBarManager != null) {
-                    statusBarManager.showScreenPinningRequest();
-                }
-                return;
-            }
-
             final ActivityStack stack = mStackSupervisor.getFocusedStack();
-            if (!isSystemInitiated && (stack == null || task != stack.topTask())) {
-                throw new IllegalArgumentException("Invalid task, not in foreground");
+            if (!isSystemInitiated) {
+                task.mLockTaskUid = callingUid;
+                if (task.mLockTaskAuth == LOCK_TASK_AUTH_PINNABLE) {
+                    // startLockTask() called by app and task mode is lockTaskModeDefault.
+                    StatusBarManagerInternal statusBarManager =
+                            LocalServices.getService(StatusBarManagerInternal.class);
+                    if (statusBarManager != null) {
+                        statusBarManager.showScreenPinningRequest();
+                    }
+                    return;
+                }
+
+                if (stack == null || task != stack.topTask()) {
+                    throw new IllegalArgumentException("Invalid task, not in foreground");
+                }
             }
             mStackSupervisor.setLockTaskModeLocked(task, isSystemInitiated ?
                     ActivityManager.LOCK_TASK_MODE_PINNED :
@@ -8614,23 +8614,15 @@
 
     @Override
     public void stopLockTaskMode() {
-        // Verify that the user matches the package of the intent for the TaskRecord
-        // we are locked to or systtem.  This will ensure the same caller for startLockTaskMode
-        // and stopLockTaskMode.
-        final int callingUid = Binder.getCallingUid();
-        if (callingUid != Process.SYSTEM_UID) {
-            try {
-                String pkg =
-                        mStackSupervisor.mLockTaskModeTask.intent.getComponent().getPackageName();
-                int uid = mContext.getPackageManager().getPackageUid(pkg,
-                        Binder.getCallingUserHandle().getIdentifier());
-                if (uid != callingUid) {
-                    throw new SecurityException("Invalid uid, expected " + uid);
-                }
-            } catch (NameNotFoundException e) {
-                Log.d(TAG, "stopLockTaskMode " + e);
-                return;
-            }
+        final TaskRecord lockTask = mStackSupervisor.getLockedTaskLocked();
+        if (lockTask == null) {
+            // Our work here is done.
+            return;
+        }
+        // Ensure the same caller for startLockTaskMode and stopLockTaskMode.
+        if (getLockTaskModeState() == ActivityManager.LOCK_TASK_MODE_LOCKED &&
+                Binder.getCallingUid() != lockTask.mLockTaskUid) {
+            throw new SecurityException("Invalid uid, expected " + lockTask.mLockTaskUid);
         }
         long ident = Binder.clearCallingIdentity();
         try {
diff --git a/services/core/java/com/android/server/am/ActivityStack.java b/services/core/java/com/android/server/am/ActivityStack.java
index 2362d28..6210d60 100644
--- a/services/core/java/com/android/server/am/ActivityStack.java
+++ b/services/core/java/com/android/server/am/ActivityStack.java
@@ -2875,7 +2875,7 @@
             }
 
             if (endTask) {
-                mStackSupervisor.endLockTaskModeIfTaskEnding(task);
+                mStackSupervisor.removeLockedTaskLocked(task);
             }
         } else if (r.state != ActivityState.PAUSING) {
             // If the activity is PAUSING, we will complete the finish once
@@ -3674,8 +3674,7 @@
         }
 
         Slog.i(TAG, "moveTaskToBack: " + tr);
-
-        mStackSupervisor.endLockTaskModeIfTaskEnding(tr);
+        mStackSupervisor.removeLockedTaskLocked(tr);
 
         // If we have a watcher, preflight the move before committing to it.  First check
         // for *other* available tasks, but if none are available, then try again allowing the
@@ -4240,7 +4239,7 @@
      */
     void removeTask(TaskRecord task, String reason, boolean notMoving) {
         if (notMoving) {
-            mStackSupervisor.endLockTaskModeIfTaskEnding(task);
+            mStackSupervisor.removeLockedTaskLocked(task);
             mWindowManager.removeTask(task.taskId);
         }
 
@@ -4345,4 +4344,10 @@
         mFullscreen = Configuration.EMPTY.equals(mOverrideConfig);
         return !mOverrideConfig.equals(oldConfig);
     }
+
+    void onLockTaskPackagesUpdatedLocked() {
+        for (int taskNdx = mTaskHistory.size() - 1; taskNdx >= 0; --taskNdx) {
+            mTaskHistory.get(taskNdx).setLockTaskAuth();
+        }
+    }
 }
diff --git a/services/core/java/com/android/server/am/ActivityStackSupervisor.java b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
index c2f6bfd..6908483 100644
--- a/services/core/java/com/android/server/am/ActivityStackSupervisor.java
+++ b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
@@ -17,10 +17,14 @@
 package com.android.server.am;
 
 import static android.Manifest.permission.START_ANY_ACTIVITY;
+import static android.app.ActivityManager.LOCK_TASK_MODE_LOCKED;
+import static android.app.ActivityManager.LOCK_TASK_MODE_NONE;
+import static android.app.ActivityManager.LOCK_TASK_MODE_PINNED;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TASK;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
 import static android.content.Intent.FLAG_ACTIVITY_TASK_ON_HOME;
+import static android.content.pm.ActivityInfo.LOCK_TASK_LAUNCH_MODE_IF_WHITELISTED;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static com.android.server.am.ActivityManagerDebugConfig.*;
 import static com.android.server.am.ActivityManagerService.FIRST_SUPERVISOR_STACK_MSG;
@@ -28,6 +32,10 @@
 import static com.android.server.am.ActivityRecord.RECENTS_ACTIVITY_TYPE;
 import static com.android.server.am.ActivityRecord.APPLICATION_ACTIVITY_TYPE;
 import static com.android.server.am.ActivityStack.ActivityState.*;
+import static com.android.server.am.TaskRecord.LOCK_TASK_AUTH_DONT_LOCK;
+import static com.android.server.am.TaskRecord.LOCK_TASK_AUTH_LAUNCHABLE;
+import static com.android.server.am.TaskRecord.LOCK_TASK_AUTH_PINNABLE;
+import static com.android.server.am.TaskRecord.LOCK_TASK_AUTH_WHITELISTED;
 
 import android.app.Activity;
 import android.app.ActivityManager;
@@ -261,17 +269,17 @@
 
     // TODO: Add listener for removal of references.
     /** Mapping from (ActivityStack/TaskStack).mStackId to their current state */
-    private SparseArray<ActivityContainer> mActivityContainers = new SparseArray<ActivityContainer>();
+    private SparseArray<ActivityContainer> mActivityContainers = new SparseArray<>();
 
     /** Mapping from displayId to display current state */
-    private final SparseArray<ActivityDisplay> mActivityDisplays =
-            new SparseArray<ActivityDisplay>();
+    private final SparseArray<ActivityDisplay> mActivityDisplays = new SparseArray<>();
 
     InputManagerInternal mInputManagerInternal;
 
-    /** If non-null then the task specified remains in front and no other tasks may be started
-     * until the task exits or #stopLockTaskMode() is called. */
-    TaskRecord mLockTaskModeTask;
+    /** The chain of tasks in lockTask mode. The current frontmost task is at the top, and tasks
+     * may be finished until there is only one entry left. If this is empty the system is not
+     * in lockTask mode. */
+    ArrayList<TaskRecord> mLockTaskModeTasks = new ArrayList<>();
     /** Store the current lock task mode. Possible values:
      * {@link ActivityManager#LOCK_TASK_MODE_NONE}, {@link ActivityManager#LOCK_TASK_MODE_LOCKED},
      * {@link ActivityManager#LOCK_TASK_MODE_PINNED}
@@ -282,8 +290,7 @@
      */
     private LockTaskNotify mLockTaskNotify;
 
-    final ArrayList<PendingActivityLaunch> mPendingActivityLaunches
-            = new ArrayList<PendingActivityLaunch>();
+    final ArrayList<PendingActivityLaunch> mPendingActivityLaunches = new ArrayList<>();
 
     /** Used to keep resumeTopActivityLocked() from being entered recursively */
     boolean inResumeTopActivity;
@@ -796,7 +803,7 @@
             ArrayList<ActivityStack> stacks = mActivityDisplays.valueAt(displayNdx).mStacks;
             for (int stackNdx = stacks.size() - 1; stackNdx >= 0; --stackNdx) {
                 final ActivityStack stack = stacks.get(stackNdx);
-                ArrayList<RunningTaskInfo> stackTaskList = new ArrayList<RunningTaskInfo>();
+                ArrayList<RunningTaskInfo> stackTaskList = new ArrayList<>();
                 runningTaskLists.add(stackTaskList);
                 stack.getTasksLocked(stackTaskList, callingUid, allowed);
             }
@@ -894,8 +901,8 @@
         intent = new Intent(intent);
 
         // Collect information about the target of the Intent.
-        ActivityInfo aInfo = resolveActivity(intent, resolvedType, startFlags,
-                profilerInfo, userId);
+        ActivityInfo aInfo =
+                resolveActivity(intent, resolvedType, startFlags, profilerInfo, userId);
 
         ActivityContainer container = (ActivityContainer)iContainer;
         synchronized (mService) {
@@ -1170,7 +1177,12 @@
         mService.updateLruProcessLocked(app, true, null);
         mService.updateOomAdjLocked();
 
-        final ActivityStack stack = r.task.stack;
+        final TaskRecord task = r.task;
+        if (task.mLockTaskAuth == LOCK_TASK_AUTH_LAUNCHABLE) {
+            setLockTaskModeLocked(task, LOCK_TASK_MODE_LOCKED, "lockTaskLaunchMode attribute");
+        }
+
+        final ActivityStack stack = task.stack;
         try {
             if (app.thread == null) {
                 throw new RemoteException();
@@ -1187,11 +1199,11 @@
             if (andResume) {
                 EventLog.writeEvent(EventLogTags.AM_RESTART_ACTIVITY,
                         r.userId, System.identityHashCode(r),
-                        r.task.taskId, r.shortComponentName);
+                        task.taskId, r.shortComponentName);
             }
             if (r.isHomeActivity() && r.isNotResolverActivity()) {
                 // Home process is the root process of the task.
-                mService.mHomeProcess = r.task.mActivities.get(0).app;
+                mService.mHomeProcess = task.mActivities.get(0).app;
             }
             mService.ensurePackageDexOpt(r.intent.getComponent().getPackageName());
             r.sleeping = false;
@@ -1233,7 +1245,7 @@
             app.thread.scheduleLaunchActivity(new Intent(r.intent), r.appToken,
                     System.identityHashCode(r), r.info, new Configuration(mService.mConfiguration),
                     new Configuration(stack.mOverrideConfig), r.compat, r.launchedFromPackage,
-                    r.task.voiceInteractor, app.repProcState, r.icicle, r.persistentState, results,
+                    task.voiceInteractor, app.repProcState, r.icicle, r.persistentState, results,
                     newIntents, !andResume, mService.isNextTransitionForward(), profilerInfo);
 
             if ((app.info.privateFlags&ApplicationInfo.PRIVATE_FLAG_CANT_SAVE_STATE) != 0) {
@@ -1946,7 +1958,7 @@
                     if ((launchFlags&Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED) != 0) {
                         intentActivity = targetStack.resetTaskIfNeededLocked(intentActivity, r);
                     }
-                    if ((startFlags&ActivityManager.START_FLAG_ONLY_IF_NEEDED) != 0) {
+                    if ((startFlags & ActivityManager.START_FLAG_ONLY_IF_NEEDED) != 0) {
                         // We don't need to start a new activity, and
                         // the client said not to do anything if that
                         // is the case, so this is it!  And for paranoia, make
@@ -1964,8 +1976,7 @@
                         }
                         return ActivityManager.START_RETURN_INTENT_TO_CALLER;
                     }
-                    if ((launchFlags &
-                            (FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TASK))
+                    if ((launchFlags & (FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TASK))
                             == (FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TASK)) {
                         // The caller has requested to completely replace any
                         // existing task with its new activity.  Well that should
@@ -2128,10 +2139,6 @@
         // Should this be considered a new task?
         if (r.resultTo == null && inTask == null && !addingToTask
                 && (launchFlags & Intent.FLAG_ACTIVITY_NEW_TASK) != 0) {
-            if (isLockTaskModeViolation(reuseTask)) {
-                Slog.e(TAG, "Attempted Lock Task Mode violation r=" + r);
-                return ActivityManager.START_RETURN_LOCK_TASK_MODE_VIOLATION;
-            }
             newTask = true;
             targetStack = computeStackFocus(r, newTask);
             targetStack.moveToFront("startingNewTask");
@@ -2147,6 +2154,10 @@
             } else {
                 r.setTask(reuseTask, taskToAffiliate);
             }
+            if (isLockTaskModeViolation(r.task)) {
+                Slog.e(TAG, "Attempted Lock Task Mode violation r=" + r);
+                return ActivityManager.START_RETURN_LOCK_TASK_MODE_VIOLATION;
+            }
             if (!movedHome) {
                 if ((launchFlags &
                         (FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_TASK_ON_HOME))
@@ -3292,6 +3303,7 @@
         pw.print(prefix); pw.println("mCurTaskId=" + mCurTaskId);
         pw.print(prefix); pw.println("mUserStackInFront=" + mUserStackInFront);
         pw.print(prefix); pw.println("mActivityContainers=" + mActivityContainers);
+        pw.print(prefix); pw.println("mLockTaskModeTasks" + mLockTaskModeTasks);
     }
 
     ArrayList<ActivityRecord> getDumpActivitiesLocked(String name) {
@@ -3592,6 +3604,32 @@
         return list;
     }
 
+    TaskRecord getLockedTaskLocked() {
+        final int top = mLockTaskModeTasks.size() - 1;
+        if (top >= 0) {
+            return mLockTaskModeTasks.get(top);
+        }
+        return null;
+    }
+
+    boolean isLockedTask(TaskRecord task) {
+        return mLockTaskModeTasks.contains(task);
+    }
+
+    boolean isLastLockedTask(TaskRecord task) {
+        return mLockTaskModeTasks.size() == 1 && mLockTaskModeTasks.contains(task);
+    }
+
+    void removeLockedTaskLocked(final TaskRecord task) {
+        if (mLockTaskModeTasks.remove(task) && mLockTaskModeTasks.isEmpty()) {
+            // Last one.
+            final Message lockTaskMsg = Message.obtain();
+            lockTaskMsg.arg1 = task.userId;
+            lockTaskMsg.what = LOCK_TASK_END_MSG;
+            mHandler.sendMessage(lockTaskMsg);
+        }
+    }
+
     void showLockTaskToast() {
         mLockTaskNotify.showToast(mLockTaskModeState);
     }
@@ -3599,42 +3637,93 @@
     void setLockTaskModeLocked(TaskRecord task, int lockTaskModeState, String reason) {
         if (task == null) {
             // Take out of lock task mode if necessary
-            if (mLockTaskModeTask != null) {
-                final Message lockTaskMsg = Message.obtain();
-                lockTaskMsg.arg1 = mLockTaskModeTask.userId;
-                lockTaskMsg.what = LOCK_TASK_END_MSG;
-                mLockTaskModeTask = null;
-                mHandler.sendMessage(lockTaskMsg);
+            final TaskRecord lockedTask = getLockedTaskLocked();
+            if (lockedTask != null) {
+                removeLockedTaskLocked(lockedTask);
+                if (!mLockTaskModeTasks.isEmpty()) {
+                    // There are locked tasks remaining, can only finish this task, not unlock it.
+                    lockedTask.performClearTaskLocked();
+                    resumeTopActivitiesLocked();
+                    return;
+                }
             }
             return;
         }
-        if (isLockTaskModeViolation(task)) {
-            Slog.e(TAG, "setLockTaskMode: Attempt to start a second Lock Task Mode task.");
+
+        // Should have already been checked, but do it again.
+        if (task.mLockTaskAuth == LOCK_TASK_AUTH_DONT_LOCK) {
             return;
         }
-        mLockTaskModeTask = task;
+        if (isLockTaskModeViolation(task)) {
+            Slog.e(TAG, "setLockTaskMode: Attempt to start an unauthorized lock task.");
+            return;
+        }
+
+        if (mLockTaskModeTasks.isEmpty()) {
+            // First locktask.
+            final Message lockTaskMsg = Message.obtain();
+            lockTaskMsg.obj = task.intent.getComponent().getPackageName();
+            lockTaskMsg.arg1 = task.userId;
+            lockTaskMsg.what = LOCK_TASK_START_MSG;
+            lockTaskMsg.arg2 = lockTaskModeState;
+            mHandler.sendMessage(lockTaskMsg);
+        }
+        // Add it or move it to the top.
+        mLockTaskModeTasks.remove(task);
+        mLockTaskModeTasks.add(task);
+
+        if (task.mLockTaskUid == -1) {
+            task.mLockTaskUid = task.mCallingUid;
+        }
         findTaskToMoveToFrontLocked(task, 0, null, reason);
         resumeTopActivitiesLocked();
-
-        final Message lockTaskMsg = Message.obtain();
-        lockTaskMsg.obj = mLockTaskModeTask.intent.getComponent().getPackageName();
-        lockTaskMsg.arg1 = mLockTaskModeTask.userId;
-        lockTaskMsg.what = LOCK_TASK_START_MSG;
-        lockTaskMsg.arg2 = lockTaskModeState;
-        mHandler.sendMessage(lockTaskMsg);
     }
 
     boolean isLockTaskModeViolation(TaskRecord task) {
-        return mLockTaskModeTask != null && mLockTaskModeTask != task;
+        if (getLockedTaskLocked() == task) {
+            return false;
+        }
+        final int lockTaskAuth = task.mLockTaskAuth;
+        switch (lockTaskAuth) {
+            case LOCK_TASK_AUTH_DONT_LOCK:
+                return !mLockTaskModeTasks.isEmpty();
+            case LOCK_TASK_AUTH_LAUNCHABLE:
+            case LOCK_TASK_AUTH_WHITELISTED:
+                return false;
+            case LOCK_TASK_AUTH_PINNABLE:
+                // Pinnable tasks can't be launched on top of locktask tasks.
+                return !mLockTaskModeTasks.isEmpty();
+            default:
+                Slog.w(TAG, "isLockTaskModeViolation: invalid lockTaskAuth value=" + lockTaskAuth);
+                return true;
+        }
     }
 
-    void endLockTaskModeIfTaskEnding(TaskRecord task) {
-        if (mLockTaskModeTask != null && mLockTaskModeTask == task) {
-            final Message lockTaskMsg = Message.obtain();
-            lockTaskMsg.arg1 = mLockTaskModeTask.userId;
-            lockTaskMsg.what = LOCK_TASK_END_MSG;
-            mLockTaskModeTask = null;
-            mHandler.sendMessage(lockTaskMsg);
+    void onLockTaskPackagesUpdatedLocked() {
+        boolean didSomething = false;
+        for (int taskNdx = mLockTaskModeTasks.size() - 1; taskNdx >= 0; --taskNdx) {
+            final TaskRecord lockedTask = mLockTaskModeTasks.get(taskNdx);
+            if (lockedTask.mLockTaskMode != LOCK_TASK_LAUNCH_MODE_IF_WHITELISTED) {
+                continue;
+            }
+            final boolean wasLaunchable = lockedTask.mLockTaskAuth == LOCK_TASK_AUTH_LAUNCHABLE;
+            lockedTask.setLockTaskAuth();
+            if (wasLaunchable && lockedTask.mLockTaskAuth != LOCK_TASK_AUTH_LAUNCHABLE) {
+                // Lost whitelisting authorization. End it now.
+                removeLockedTaskLocked(lockedTask);
+                lockedTask.performClearTaskLocked();
+                didSomething = true;
+            }
+        }
+        for (int displayNdx = mActivityDisplays.size() - 1; displayNdx >= 0; --displayNdx) {
+            ArrayList<ActivityStack> stacks = mActivityDisplays.valueAt(displayNdx).mStacks;
+            for (int stackNdx = stacks.size() - 1; stackNdx >= 0; --stackNdx) {
+                final ActivityStack stack = stacks.get(stackNdx);
+                stack.onLockTaskPackagesUpdatedLocked();
+            }
+        }
+        if (didSomething) {
+            resumeTopActivitiesLocked();
         }
     }
 
@@ -3734,11 +3823,10 @@
                         mLockTaskModeState = msg.arg2;
                         if (getStatusBarService() != null) {
                             int flags = 0;
-                            if (mLockTaskModeState == ActivityManager.LOCK_TASK_MODE_LOCKED) {
+                            if (mLockTaskModeState == LOCK_TASK_MODE_LOCKED) {
                                 flags = StatusBarManager.DISABLE_MASK
                                         & (~StatusBarManager.DISABLE_BACK);
-                            } else if (mLockTaskModeState ==
-                                    ActivityManager.LOCK_TASK_MODE_PINNED) {
+                            } else if (mLockTaskModeState == LOCK_TASK_MODE_PINNED) {
                                 flags = StatusBarManager.DISABLE_MASK
                                         & (~StatusBarManager.DISABLE_BACK)
                                         & (~StatusBarManager.DISABLE_HOME)
@@ -3776,8 +3864,7 @@
                             boolean shouldLockKeyguard = Settings.Secure.getInt(
                                     mService.mContext.getContentResolver(),
                                     Settings.Secure.LOCK_TO_APP_EXIT_LOCKED) != 0;
-                            if (mLockTaskModeState == ActivityManager.LOCK_TASK_MODE_PINNED &&
-                                    shouldLockKeyguard) {
+                            if (mLockTaskModeState == LOCK_TASK_MODE_PINNED && shouldLockKeyguard) {
                                 mWindowManager.lockNow(null);
                                 mWindowManager.dismissKeyguard();
                                 new LockPatternUtils(mService.mContext)
@@ -3789,7 +3876,7 @@
                     } catch (RemoteException ex) {
                         throw new RuntimeException(ex);
                     } finally {
-                        mLockTaskModeState = ActivityManager.LOCK_TASK_MODE_NONE;
+                        mLockTaskModeState = LOCK_TASK_MODE_NONE;
                     }
                 } break;
                 case CONTAINER_CALLBACK_TASK_LIST_EMPTY: {
diff --git a/services/core/java/com/android/server/am/TaskRecord.java b/services/core/java/com/android/server/am/TaskRecord.java
index 82e6d47..790a78d 100644
--- a/services/core/java/com/android/server/am/TaskRecord.java
+++ b/services/core/java/com/android/server/am/TaskRecord.java
@@ -18,6 +18,10 @@
 
 import static android.content.Intent.FLAG_ACTIVITY_NEW_DOCUMENT;
 import static android.content.Intent.FLAG_ACTIVITY_RETAIN_IN_RECENTS;
+import static android.content.pm.ActivityInfo.LOCK_TASK_LAUNCH_MODE_ALWAYS;
+import static android.content.pm.ActivityInfo.LOCK_TASK_LAUNCH_MODE_DEFAULT;
+import static android.content.pm.ActivityInfo.LOCK_TASK_LAUNCH_MODE_IF_WHITELISTED;
+import static android.content.pm.ActivityInfo.LOCK_TASK_LAUNCH_MODE_NEVER;
 import static com.android.server.am.ActivityManagerDebugConfig.*;
 import static com.android.server.am.ActivityRecord.HOME_ACTIVITY_TYPE;
 import static com.android.server.am.ActivityRecord.APPLICATION_ACTIVITY_TYPE;
@@ -121,6 +125,20 @@
 
     boolean mResizeable;    // Activities in the task resizeable. Based on the resizable setting of
                             // the root activity.
+    int mLockTaskMode;      // Which tasklock mode to launch this task in. One of
+                            // ActivityManager.LOCK_TASK_LAUNCH_MODE_*
+    /** Can't be put in lockTask mode. */
+    final static int LOCK_TASK_AUTH_DONT_LOCK = 0;
+    /** Can enter lockTask with user approval if not already in lockTask. */
+    final static int LOCK_TASK_AUTH_PINNABLE = 1;
+    /** Starts in LOCK_TASK_MODE_LOCKED automatically. Can start over existing lockTask task. */
+    final static int LOCK_TASK_AUTH_LAUNCHABLE = 2;
+    /** Enters LOCK_TASK_MODE_LOCKED via startLockTask(), enters LOCK_TASK_MODE_PINNED from
+     * Overview. Can start over existing lockTask task. */
+    final static int LOCK_TASK_AUTH_WHITELISTED = 3;
+    int mLockTaskAuth = LOCK_TASK_AUTH_PINNABLE;
+
+    int mLockTaskUid = -1;  // The uid of the application that called startLockTask().
 
     // This represents the last resolved activity values for this task
     // NOTE: This value needs to be persisted with each task
@@ -186,6 +204,8 @@
         voiceInteractor = _voiceInteractor;
         isAvailable = true;
         mActivities = new ArrayList<>();
+        mCallingUid = info.applicationInfo.uid;
+        mCallingPackage = info.packageName;
         setIntent(_intent, info);
     }
 
@@ -201,12 +221,12 @@
         voiceInteractor = null;
         isAvailable = true;
         mActivities = new ArrayList<>();
+        mCallingUid = info.applicationInfo.uid;
+        mCallingPackage = info.packageName;
         setIntent(_intent, info);
 
         taskType = ActivityRecord.APPLICATION_ACTIVITY_TYPE;
         isPersistable = true;
-        mCallingUid = info.applicationInfo.uid;
-        mCallingPackage = info.packageName;
         // Clamp to [1, max].
         maxRecents = Math.min(Math.max(info.maxRecents, 1),
                 ActivityManager.getMaxAppRecentsLimitStatic());
@@ -215,8 +235,6 @@
         mTaskToReturnTo = HOME_ACTIVITY_TYPE;
         userId = UserHandle.getUserId(info.applicationInfo.uid);
         lastTaskDescription = _taskDescription;
-        mCallingUid = info.applicationInfo.uid;
-        mCallingPackage = info.packageName;
     }
 
     private TaskRecord(ActivityManagerService service, int _taskId, Intent _intent,
@@ -278,9 +296,9 @@
 
     /** Sets the original intent, and the calling uid and package. */
     void setIntent(ActivityRecord r) {
-        setIntent(r.intent, r.info);
         mCallingUid = r.launchedFromUid;
         mCallingPackage = r.launchedFromPackage;
+        setIntent(r.intent, r.info);
     }
 
     /** Sets the original intent, _without_ updating the calling uid or package. */
@@ -362,6 +380,8 @@
             autoRemoveRecents = false;
         }
         mResizeable = info.resizeable;
+        mLockTaskMode = info.lockTaskLaunchMode;
+        setLockTaskAuth();
     }
 
     void setTaskToReturnTo(int taskToReturnTo) {
@@ -716,6 +736,53 @@
         performClearTaskAtIndexLocked(0);
     }
 
+    private boolean isPrivileged() {
+        final ProcessRecord proc = mService.mProcessNames.get(mCallingPackage, mCallingUid);
+        if (proc != null) {
+                return (proc.info.privateFlags & ApplicationInfo.PRIVATE_FLAG_PRIVILEGED) != 0;
+        }
+        return false;
+    }
+
+    void setLockTaskAuth() {
+        switch (mLockTaskMode) {
+            case LOCK_TASK_LAUNCH_MODE_DEFAULT:
+                mLockTaskAuth = isLockTaskWhitelistedLocked() ?
+                    LOCK_TASK_AUTH_WHITELISTED : LOCK_TASK_AUTH_PINNABLE;
+                break;
+
+            case LOCK_TASK_LAUNCH_MODE_NEVER:
+                mLockTaskAuth = isPrivileged() ?
+                        LOCK_TASK_AUTH_DONT_LOCK : LOCK_TASK_AUTH_PINNABLE;
+                break;
+
+            case LOCK_TASK_LAUNCH_MODE_ALWAYS:
+                mLockTaskAuth = isPrivileged() ?
+                        LOCK_TASK_AUTH_LAUNCHABLE: LOCK_TASK_AUTH_PINNABLE;
+                break;
+
+            case LOCK_TASK_LAUNCH_MODE_IF_WHITELISTED:
+                mLockTaskAuth = isLockTaskWhitelistedLocked() ?
+                        LOCK_TASK_AUTH_LAUNCHABLE : LOCK_TASK_AUTH_PINNABLE;
+                break;
+        }
+    }
+
+    boolean isLockTaskWhitelistedLocked() {
+        if (mCallingPackage == null) {
+            return false;
+        }
+        String[] packages = mService.mLockTaskPackages.get(userId);
+        if (packages == null) {
+            return false;
+        }
+        for (int i = packages.length - 1; i >= 0; --i) {
+            if (mCallingPackage.equals(packages[i])) {
+                return true;
+            }
+        }
+        return false;
+    }
     boolean isHomeTask() {
         return taskType == HOME_ACTIVITY_TYPE;
     }
diff --git a/services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java b/services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java
index 452b3eb..e22a2cc 100644
--- a/services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java
+++ b/services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java
@@ -1638,10 +1638,13 @@
 
     private void updateLockTaskPackagesLocked(DevicePolicyData policy, int userId) {
         IActivityManager am = ActivityManagerNative.getDefault();
+        long ident = Binder.clearCallingIdentity();
         try {
             am.updateLockTaskPackages(userId, policy.mLockTaskPackages.toArray(new String[0]));
         } catch (RemoteException e) {
             // Not gonna happen.
+        } finally {
+            Binder.restoreCallingIdentity(ident);
         }
     }