Make Trusted Hotword session permissions follow previous behavior

A prior change to the permissions flow for Trusted Hotword
(I80dabaf6ae0e781028dde16ead3321fbff319542) made the system enforce
the required permissions on the APIs the conventional way - by throwing
a SecurityException. But the existing behavior was to silence these
exceptions and instead return error results. This change brings back
the old behavior which exists in the SoundTrigger layer.

Also removes permissions checks for a couple of APIs to again be
consistent with the old behavior (and the current behavior in the
SoundTrigger layer).

Fix: 193116894
Test: manual - remove permission and reboot / remove permission after
 boot, stop/start reco
Test: atest HotwordDetectionServiceBasicTest
Change-Id: I56391260fd4375a04233eb3261bacec8696bda99

core/java/android/service/voice/AlwaysOnHotwordDetector.java

@@ -783,6 +783,9 @@ public class AlwaysOnHotwordDetector extends AbstractHotwordDetector {
      *         This may happen if another detector has been instantiated or the
      *         {@link VoiceInteractionService} hosting this detector has been shut down.
      */
+    // TODO: Remove this RequiresPermission since it isn't actually enforced. Also fix the javadoc
+    // about permissions enforcement (when it throws vs when it just returns false) for other
+    // methods in this class.
     @RequiresPermission(allOf = {RECORD_AUDIO, CAPTURE_AUDIO_HOTWORD})
     @Override
     public boolean stopRecognition() {

core/java/android/service/voice/SoftwareHotwordDetector.java

@@ -82,6 +82,9 @@ class SoftwareHotwordDetector extends AbstractHotwordDetector {
         try {
             mManagerService.startListeningFromMic(
                     mAudioFormat, new BinderCallback(mHandler, mCallback));
+        } catch (SecurityException e) {
+            Slog.e(TAG, "startRecognition failed: " + e);
+            return false;
         } catch (RemoteException e) {
             e.rethrowFromSystemServer();
         }

services/voiceinteraction/java/com/android/server/voiceinteraction/SoundTriggerSessionPermissionsDecorator.java

@@ -60,7 +60,7 @@ final class SoundTriggerSessionPermissionsDecorator implements
 
     @Override
     public SoundTrigger.ModuleProperties getDspModuleProperties() throws RemoteException {
-        // No permission needed.
+        // No permission needed here (the app must have the Assistant Role to retrieve the session).
         return mDelegate.getDspModuleProperties();
     }
 
@@ -71,7 +71,9 @@ final class SoundTriggerSessionPermissionsDecorator implements
         if (DEBUG) {
             Slog.d(TAG, "startRecognition");
         }
-        enforcePermissions();
+        if (!isHoldingPermissions()) {
+            return SoundTrigger.STATUS_PERMISSION_DENIED;
+        }
         return mDelegate.startRecognition(i, s, iHotwordRecognitionStatusCallback,
                 recognitionConfig, b);
     }
@@ -80,25 +82,28 @@ final class SoundTriggerSessionPermissionsDecorator implements
     public int stopRecognition(int i,
             IHotwordRecognitionStatusCallback iHotwordRecognitionStatusCallback)
             throws RemoteException {
-        enforcePermissions();
+        // Stopping a model does not require special permissions. Having a handle to the session is
+        // sufficient.
         return mDelegate.stopRecognition(i, iHotwordRecognitionStatusCallback);
     }
 
     @Override
     public int setParameter(int i, int i1, int i2) throws RemoteException {
-        enforcePermissions();
+        if (!isHoldingPermissions()) {
+            return SoundTrigger.STATUS_PERMISSION_DENIED;
+        }
         return mDelegate.setParameter(i, i1, i2);
     }
 
     @Override
     public int getParameter(int i, int i1) throws RemoteException {
-        enforcePermissions();
+        // No permission needed here (the app must have the Assistant Role to retrieve the session).
         return mDelegate.getParameter(i, i1);
     }
 
     @Override
     public SoundTrigger.ModelParamRange queryParameter(int i, int i1) throws RemoteException {
-        enforcePermissions();
+        // No permission needed here (the app must have the Assistant Role to retrieve the session).
         return mDelegate.queryParameter(i, i1);
     }
 
@@ -109,9 +114,15 @@ final class SoundTriggerSessionPermissionsDecorator implements
     }
 
     // TODO: Share this code with SoundTriggerMiddlewarePermission.
-    private void enforcePermissions() {
-        enforcePermissionForPreflight(mContext, mOriginatorIdentity, RECORD_AUDIO);
-        enforcePermissionForPreflight(mContext, mOriginatorIdentity, CAPTURE_AUDIO_HOTWORD);
+    private boolean isHoldingPermissions() {
+        try {
+            enforcePermissionForPreflight(mContext, mOriginatorIdentity, RECORD_AUDIO);
+            enforcePermissionForPreflight(mContext, mOriginatorIdentity, CAPTURE_AUDIO_HOTWORD);
+            return true;
+        } catch (SecurityException e) {
+            Slog.e(TAG, e.toString());
+            return false;
+        }
     }
 
     /**