Delete keystore keys from RecoveryService.rebootRecoveryWithCommand()

Adds deleteSecrets() to RecoverySystemService. This method is called
from rebootRecoveryWithCommand () before the --wipe_data command is
passed to recovery and the device is force-rebooted.

deleteSecerts() calls IKeystoreMaintenance.deleteAllKeys() in order to
quickly destroy the keys protecting the synthetic password blobs
used to derive FBE encryption keys.

The intent is to make FBE-encrypted data unrecoverable even if the full
data wipe in recovery is interrupted or skipped.

Bug: 324321147
Test: Manual - System -> Reset options -> Erase all data.
Test: Hold VolDown key to interrupt reboot and stop at bootloader
screen.
Test: fastboot oem bcd wipe command && fastboot oem bcd wipe recovery
Test: fastboot reboot
Test: Device reboots into recovery and prompts to factory reset:
Test: 'Cannot load Android system. Your data may be corrupt. ...'
(cherry picked from https://android-review.googlesource.com/q/commit:0d00031851e9f5d8ef93947205a7e8b5257f0d8d)
Merged-In: I5eb8e97f3ae1a18d5e7e7c2c7eca048ebff3440a
Change-Id: I5eb8e97f3ae1a18d5e7e7c2c7eca048ebff3440a

keystore/java/android/security/AndroidKeyStoreMaintenance.java

@@ -243,4 +243,24 @@ public class AndroidKeyStoreMaintenance {
                     "Keystore error while trying to get apps affected by SID.");
         }
     }
+
+    /**
+    * Deletes all keys in all KeyMint devices.
+    * Called by RecoverySystem before rebooting to recovery in order to delete all KeyMint keys,
+    * including synthetic password protector keys (used by LockSettingsService), as well as keys
+    * protecting DE and metadata encryption keys (used by vold). This ensures that FBE-encrypted
+    * data is unrecoverable even if the data wipe in recovery is interrupted or skipped.
+    */
+    public static void deleteAllKeys() throws KeyStoreException {
+        StrictMode.noteDiskWrite();
+        try {
+            getService().deleteAllKeys();
+        } catch (RemoteException | NullPointerException e) {
+            throw new KeyStoreException(SYSTEM_ERROR,
+                    "Failure to connect to Keystore while trying to delete all keys.");
+        } catch (ServiceSpecificException e) {
+            throw new KeyStoreException(e.errorCode,
+                    "Keystore error while trying to delete all keys.");
+        }
+    }
 }

services/core/java/com/android/server/recoverysystem/RecoverySystemService.java

@@ -52,6 +52,7 @@ import android.os.ServiceManager;
 import android.os.ShellCallback;
 import android.os.SystemProperties;
 import android.provider.DeviceConfig;
+import android.security.AndroidKeyStoreMaintenance;
 import android.util.ArrayMap;
 import android.util.ArraySet;
 import android.util.FastImmutableArraySet;
@@ -68,6 +69,7 @@ import com.android.server.SystemService;
 import com.android.server.Watchdog;
 import com.android.server.pm.ApexManager;
 import com.android.server.recoverysystem.hal.BootControlHIDL;
+import com.android.server.utils.Slogf;
 
 import libcore.io.IoUtils;
 
@@ -122,6 +124,8 @@ public class RecoverySystemService extends IRecoverySystem.Stub implements Reboo
     static final String LSKF_CAPTURED_TIMESTAMP_PREF = "lskf_captured_timestamp";
     static final String LSKF_CAPTURED_COUNT_PREF = "lskf_captured_count";
 
+    static final String RECOVERY_WIPE_DATA_COMMAND = "--wipe_data";
+
     private final Injector mInjector;
     private final Context mContext;
 
@@ -525,18 +529,35 @@ public class RecoverySystemService extends IRecoverySystem.Stub implements Reboo
     @Override // Binder call
     public void rebootRecoveryWithCommand(String command) {
         if (DEBUG) Slog.d(TAG, "rebootRecoveryWithCommand: [" + command + "]");
+
+        boolean isForcedWipe = command != null && command.contains(RECOVERY_WIPE_DATA_COMMAND);
         synchronized (sRequestLock) {
             if (!setupOrClearBcb(true, command)) {
                 Slog.e(TAG, "rebootRecoveryWithCommand failed to setup BCB");
                 return;
             }
 
+            if (isForcedWipe) {
+                deleteSecrets();
+                // TODO: consider adding a dedicated forced-wipe-reboot method to PowerManager and
+                // calling here.
+            }
+
             // Having set up the BCB, go ahead and reboot.
             PowerManager pm = mInjector.getPowerManager();
             pm.reboot(PowerManager.REBOOT_RECOVERY);
         }
     }
 
+    private static void deleteSecrets() {
+        Slogf.w(TAG, "deleteSecrets");
+        try {
+            AndroidKeyStoreMaintenance.deleteAllKeys();
+        } catch (android.security.KeyStoreException e) {
+            Log.wtf(TAG, "Failed to delete all keys from keystore.", e);
+        }
+    }
+
     private void enforcePermissionForResumeOnReboot() {
         if (mContext.checkCallingOrSelfPermission(android.Manifest.permission.RECOVERY)
                 != PackageManager.PERMISSION_GRANTED