From 78e388067853551178196d6979562eb82a1dfc05 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 a biometric
sensor of the convenience strength class.

Bug: 200005662
Test: blueline + R vendor w/o the config + S GSI
Change-Id: I70e16089fa4285b1a382d9433af4fc3523b88fc8
---
 .../server/biometrics/AuthService.java        | 50 +++++++++++++++++--
 1 file changed, 47 insertions(+), 3 deletions(-)

diff --git a/services/core/java/com/android/server/biometrics/AuthService.java b/services/core/java/com/android/server/biometrics/AuthService.java
index 0cd2e3d0ff593..41fb93cdc6a39 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;
@@ -81,6 +82,7 @@ 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 final Injector mInjector;
 
@@ -624,9 +626,19 @@ public class AuthService extends SystemService {
         final SensorConfig[] hidlConfigs;
         if (!mInjector.isHidlDisabled(getContext())) {
             final String[] configStrings = mInjector.getConfiguration(getContext());
-            hidlConfigs = new SensorConfig[configStrings.length];
-            for (int i = 0; i < configStrings.length; ++i) {
-                hidlConfigs[i] = new SensorConfig(configStrings[i]);
+            final boolean isRVendor = SystemProperties.getInt(SYSPROP_FIRST_API_LEVEL, 0)
+                    == Build.VERSION_CODES.R;
+            if (configStrings.length == 0 && isRVendor) {
+                // 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");
+                hidlConfigs = generateRSdkCompatibleConfiguration();
+            } else {
+                hidlConfigs = new SensorConfig[configStrings.length];
+                for (int i = 0; i < configStrings.length; ++i) {
+                    hidlConfigs[i] = new SensorConfig(configStrings[i]);
+                }
             }
         } else {
             hidlConfigs = null;
@@ -638,6 +650,38 @@ public class AuthService extends SystemService {
         mInjector.publishBinderService(this, mImpl);
     }
 
+    /**
+     * Generates SensorConfig[] with an entry that corresponds to the biometric feature declared on
+     * the device. Returns an empty SensorConfig[] if no biometric features are declared. If both
+     * fingerprint and face are declared, only the fingerprint config will be generated. Biometrics
+     * are assumed to be of the weakest strength class, i.e. convenience.
+     */
+    private @NonNull SensorConfig[] generateRSdkCompatibleConfiguration() {
+        final boolean hasFp = getContext().getPackageManager().hasSystemFeature(
+                PackageManager.FEATURE_FINGERPRINT);
+        final boolean hasFace = getContext().getPackageManager().hasSystemFeature(
+                PackageManager.FEATURE_FACE);
+        if (hasFp || hasFace) {
+            final String id = "0";
+            final String strength = String.valueOf(Authenticators.BIOMETRIC_CONVENIENCE);
+            final String modality;
+            final String logStr;
+            if (hasFp) {
+                modality = String.valueOf(BiometricAuthenticator.TYPE_FINGERPRINT);
+                logStr = "fingerprint";
+            } else {
+                modality = String.valueOf(BiometricAuthenticator.TYPE_FACE);
+                logStr = "face";
+            }
+            final String config = String.join(":" /* delimiter */, id, modality, strength);
+            Slog.d(TAG, "Generated config_biometric_sensors for " + logStr + ": " + config);
+            return new SensorConfig[]{new SensorConfig(config)};
+        } else {
+            Slog.d(TAG, "Couldn't generate config_biometric_sensors. No biometrics found.");
+            return new SensorConfig[0];
+        }
+    }
+
     /**
      * Registers HIDL and AIDL authenticators for all of the available modalities.
      *