From 61787c4e852d58fca2f0a12acf0d534382dbae6c Mon Sep 17 00:00:00 2001
From: Nikolay Elenkov <nikolayelenkov@google.com>
Date: Thu, 21 Mar 2024 08:54:27 +0000
Subject: [PATCH] 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. ...'

Change-Id: I5eb8e97f3ae1a18d5e7e7c2c7eca048ebff3440a
---
 .../security/AndroidKeyStoreMaintenance.java  | 21 +++++++++++++++++++
 .../recoverysystem/RecoverySystemService.java | 21 +++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/keystore/java/android/security/AndroidKeyStoreMaintenance.java b/keystore/java/android/security/AndroidKeyStoreMaintenance.java
index 2beb434566e5..83c2444e5b86 100644
--- a/keystore/java/android/security/AndroidKeyStoreMaintenance.java
+++ b/keystore/java/android/security/AndroidKeyStoreMaintenance.java
@@ -18,6 +18,7 @@
 
 import android.annotation.NonNull;
 import android.annotation.Nullable;
+import android.os.RemoteException;
 import android.os.ServiceManager;
 import android.os.ServiceSpecificException;
 import android.os.StrictMode;
@@ -218,4 +219,24 @@ public static int migrateKeyNamespace(KeyDescriptor source, KeyDescriptor destin
             return SYSTEM_ERROR;
         }
     }
+
+    /**
+    * 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.");
+        }
+    }
 }
diff --git a/services/core/java/com/android/server/recoverysystem/RecoverySystemService.java b/services/core/java/com/android/server/recoverysystem/RecoverySystemService.java
index 375ef6150830..f36538c9b3c4 100644
--- a/services/core/java/com/android/server/recoverysystem/RecoverySystemService.java
+++ b/services/core/java/com/android/server/recoverysystem/RecoverySystemService.java
@@ -52,6 +52,7 @@
 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;
@@ -67,6 +68,7 @@
 import com.android.server.SystemService;
 import com.android.server.pm.ApexManager;
 import com.android.server.recoverysystem.hal.BootControlHIDL;
+import com.android.server.utils.Slogf;
 
 import libcore.io.IoUtils;
 
@@ -118,6 +120,8 @@ 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;
 
@@ -521,17 +525,34 @@ public boolean setupBcb(String command) {
     @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)) {
                 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