Disable multi-user background recording

On user switch, kill existing processes of the background user with
android.permission.RECORD_AUDIO permission. Home activity should not be
killed to avoid an expensive restart of the home launcher, when the
user switches back.

Introduced DISALLOW_RECORD_AUDIO user restriction, which is enabled for the
background user, and removed for the foreground user.

Introduced a concept of system controlled user restriction, which can only
be set by the system, rather than device administrator.

Bug: 20346194
Change-Id: Ic942fd565e80d14424230dae612965a8e229c4ef

4 files changed, 25 insertions, 4 deletions

diff --git a/core/java/android/app/ActivityManagerInternal.java b/core/java/android/app/ActivityManagerInternal.java
index bde8f39..40eb799 100644
--- a/core/java/android/app/ActivityManagerInternal.java
+++ b/core/java/android/app/ActivityManagerInternal.java
@@ -17,6 +17,7 @@
 package android.app;
 
 import android.annotation.NonNull;
+import android.content.ComponentName;
 
 /**
  * Activity manager local system service interface.
@@ -48,4 +49,10 @@ public abstract class ActivityManagerInternal {
          */
         public abstract void release();
     }
+
+    /**
+     * Returns home activity for the specified user.
+     * @param userId ID of the user or {@link android.os.UserHandle#USER_ALL}
+     */
+    public abstract ComponentName getHomeActivityForUser(int userId);
 }
diff --git a/core/java/android/app/AppOpsManager.java b/core/java/android/app/AppOpsManager.java
index 5aa399b..7104185 100644
--- a/core/java/android/app/AppOpsManager.java
+++ b/core/java/android/app/AppOpsManager.java
@@ -606,7 +606,7 @@ public class AppOpsManager {
             UserManager.DISALLOW_CREATE_WINDOWS, //SYSTEM_ALERT_WINDOW
             null, //ACCESS_NOTIFICATIONS
             null, //CAMERA
-            null, //RECORD_AUDIO
+            UserManager.DISALLOW_RECORD_AUDIO, //RECORD_AUDIO
             null, //PLAY_AUDIO
             null, //READ_CLIPBOARD
             null, //WRITE_CLIPBOARD
diff --git a/core/java/android/os/IUserManager.aidl b/core/java/android/os/IUserManager.aidl
index 811418b..f212daf 100644
--- a/core/java/android/os/IUserManager.aidl
+++ b/core/java/android/os/IUserManager.aidl
@@ -45,6 +45,8 @@ interface IUserManager {
     Bundle getUserRestrictions(int userHandle);
     boolean hasUserRestriction(in String restrictionKey, int userHandle);
     void setUserRestrictions(in Bundle restrictions, int userHandle);
+    void setUserRestriction(String key, boolean value, int userId);
+    void setSystemControlledUserRestriction(String key, boolean value, int userId);
     void setApplicationRestrictions(in String packageName, in Bundle restrictions,
             int userHandle);
     Bundle getApplicationRestrictions(in String packageName);
diff --git a/core/java/android/os/UserManager.java b/core/java/android/os/UserManager.java
index c7ac7ce..cc37d5e 100644
--- a/core/java/android/os/UserManager.java
+++ b/core/java/android/os/UserManager.java
@@ -412,6 +412,16 @@ public class UserManager {
     public static final String DISALLOW_SAFE_BOOT = "no_safe_boot";
 
     /**
+     * Specifies if a user is not allowed to record audio. This restriction is always enabled for
+     * background users. The default value is <code>false</code>.
+     *
+     * @see #setUserRestrictions(Bundle)
+     * @see #getUserRestrictions()
+     * @hide
+     */
+    public static final String DISALLOW_RECORD_AUDIO = "no_record_audio";
+
+    /**
      * Application restriction key that is used to indicate the pending arrival
      * of real restrictions for the app.
      *
@@ -688,9 +698,11 @@ public class UserManager {
      */
     @Deprecated
     public void setUserRestriction(String key, boolean value, UserHandle userHandle) {
-        Bundle bundle = getUserRestrictions(userHandle);
-        bundle.putBoolean(key, value);
-        setUserRestrictions(bundle, userHandle);
+        try {
+            mService.setUserRestriction(key, value, userHandle.getIdentifier());
+        } catch (RemoteException re) {
+            Log.w(TAG, "Could not set user restriction", re);
+        }
     }
 
     /**