From a1c5ce250aa96774656345dd57150422fc06aa63 Mon Sep 17 00:00:00 2001
From: Ilya Matyukhin <ilyamaty@google.com>
Date: Wed, 15 Sep 2021 01:58:50 -0700
Subject: [PATCH] Assume convenience for biometrics not configured in R

This change restores R biometric behavior for devices that:
- Declare FEATURE_FINGERPRINT or FEATURE_FACE
- Have an empty config_biometric_sensors in config.xml
- Report ro.board.[first_]api_level as 30 (R)

The behavior is restored by assuming that the device has biometrics
sensors of the convenience strength class.

Bug: 200005662
Bug: 198692048
Test: blueline + R vendor w/o the config + S GSI
Change-Id: I2ae8b746bb5247b5bb6ef9929b3a11ad5403ca48
Merged-In: I2ae8b746bb5247b5bb6ef9929b3a11ad5403ca48
---
 .../server/biometrics/AuthService.java        | 40 ++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/services/core/java/com/android/server/biometrics/AuthService.java b/services/core/java/com/android/server/biometrics/AuthService.java
index 0cd2e3d0ff593..c97ad55ceeec7 100644
--- a/services/core/java/com/android/server/biometrics/AuthService.java
+++ b/services/core/java/com/android/server/biometrics/AuthService.java
@@ -60,6 +60,7 @@ import android.os.Build;
 import android.os.IBinder;
 import android.os.RemoteException;
 import android.os.ServiceManager;
+import android.os.SystemProperties;
 import android.os.UserHandle;
 import android.provider.Settings;
 import android.util.Slog;
@@ -70,6 +71,7 @@ import com.android.internal.util.ArrayUtils;
 import com.android.server.SystemService;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 
 /**
@@ -81,6 +83,8 @@ public class AuthService extends SystemService {
     private static final String SETTING_HIDL_DISABLED =
             "com.android.server.biometrics.AuthService.hidlDisabled";
     private static final int DEFAULT_HIDL_DISABLED = 0;
+    private static final String SYSPROP_FIRST_API_LEVEL = "ro.board.first_api_level";
+    private static final String SYSPROP_API_LEVEL = "ro.board.api_level";
 
     private final Injector mInjector;
 
@@ -623,7 +627,16 @@ public class AuthService extends SystemService {
 
         final SensorConfig[] hidlConfigs;
         if (!mInjector.isHidlDisabled(getContext())) {
-            final String[] configStrings = mInjector.getConfiguration(getContext());
+            final int firstApiLevel = SystemProperties.getInt(SYSPROP_FIRST_API_LEVEL, 0);
+            final int apiLevel = SystemProperties.getInt(SYSPROP_API_LEVEL, firstApiLevel);
+            String[] configStrings = mInjector.getConfiguration(getContext());
+            if (configStrings.length == 0 && apiLevel == Build.VERSION_CODES.R) {
+                // For backwards compatibility with R where biometrics could work without being
+                // configured in config_biometric_sensors. In the absence of a vendor provided
+                // configuration, we assume the weakest biometric strength (i.e. convenience).
+                Slog.w(TAG, "Found R vendor partition without config_biometric_sensors");
+                configStrings = generateRSdkCompatibleConfiguration();
+            }
             hidlConfigs = new SensorConfig[configStrings.length];
             for (int i = 0; i < configStrings.length; ++i) {
                 hidlConfigs[i] = new SensorConfig(configStrings[i]);
@@ -638,6 +651,31 @@ public class AuthService extends SystemService {
         mInjector.publishBinderService(this, mImpl);
     }
 
+    /**
+     * Generates an array of string configs with entries that correspond to the biometric features
+     * declared on the device. Returns an empty array if no biometric features are declared.
+     * Biometrics are assumed to be of the weakest strength class, i.e. convenience.
+     */
+    private @NonNull String[] generateRSdkCompatibleConfiguration() {
+        final PackageManager pm = getContext().getPackageManager();
+        final ArrayList<String> modalities = new ArrayList<>();
+        if (pm.hasSystemFeature(PackageManager.FEATURE_FINGERPRINT)) {
+            modalities.add(String.valueOf(BiometricAuthenticator.TYPE_FINGERPRINT));
+        }
+        if (pm.hasSystemFeature(PackageManager.FEATURE_FACE)) {
+            modalities.add(String.valueOf(BiometricAuthenticator.TYPE_FACE));
+        }
+        final String strength = String.valueOf(Authenticators.BIOMETRIC_CONVENIENCE);
+        final String[] configStrings = new String[modalities.size()];
+        for (int i = 0; i < modalities.size(); ++i) {
+            final String id = String.valueOf(i);
+            final String modality = modalities.get(i);
+            configStrings[i] = String.join(":" /* delimiter */, id, modality, strength);
+        }
+        Slog.d(TAG, "Generated config_biometric_sensors: " + Arrays.toString(configStrings));
+        return configStrings;
+    }
+
     /**
      * Registers HIDL and AIDL authenticators for all of the available modalities.
      *