Fix clearing of retained password

HW accelerated FDE requires both old and new password to be sent to
secure side to verify and update password. This requires storing of
old password until password is verified. Initial approach of clearing
old password after 60 seconds has a bug which resets old password to
default if user delays entering new password. This fix would gives
caller the responsibility to clear the password once password is
updated.

Change-Id: I0ea5cb92ec3908e31c081ce2af6a190c67aadc7b

4 files changed, 28 insertions, 11 deletions

diff --git a/core/java/com/android/internal/widget/ILockSettings.aidl b/core/java/com/android/internal/widget/ILockSettings.aidl
index dfb7c50..3fb0afc 100644
--- a/core/java/com/android/internal/widget/ILockSettings.aidl
+++ b/core/java/com/android/internal/widget/ILockSettings.aidl
@@ -35,4 +35,5 @@ interface ILockSettings {
     boolean checkVoldPassword(int userId);
     boolean havePattern(int userId);
     boolean havePassword(int userId);
+    void sanitizePassword();
 }
diff --git a/core/java/com/android/internal/widget/LockPatternUtils.java b/core/java/com/android/internal/widget/LockPatternUtils.java
index 86d11be..72e97d3 100644
--- a/core/java/com/android/internal/widget/LockPatternUtils.java
+++ b/core/java/com/android/internal/widget/LockPatternUtils.java
@@ -529,6 +529,17 @@ public class LockPatternUtils {
         }
     }
 
+    /**
+     * clears stored password.
+     */
+    public void sanitizePassword() {
+        try {
+            getLockSettings().sanitizePassword();
+        } catch (RemoteException re) {
+            Log.e(TAG, "Couldn't sanitize password" + re);
+        }
+    }
+
     private void updateCryptoUserInfo(int userId) {
         if (userId != UserHandle.USER_OWNER) {
             return;
diff --git a/services/core/java/com/android/server/LockSettingsService.java b/services/core/java/com/android/server/LockSettingsService.java
index c844c2c..11b7ebc 100644
--- a/services/core/java/com/android/server/LockSettingsService.java
+++ b/services/core/java/com/android/server/LockSettingsService.java
@@ -70,6 +70,8 @@ public class LockSettingsService extends ILockSettings.Stub {
 
     private static final String TAG = "LockSettingsService";
 
+    private static final String DEFAULT_PASSWORD = "default_password";
+
     private final Context mContext;
 
     private final LockSettingsStorage mStorage;
@@ -77,9 +79,7 @@ public class LockSettingsService extends ILockSettings.Stub {
     private LockPatternUtils mLockPatternUtils;
     private boolean mFirstCallToVold;
     private IGateKeeperService mGateKeeperService;
-    private static String mSavePassword = "default_password";
-    private static final long CLEAR_PASSWORD_INTERVAL = 60 * 1000; // 1m
-    protected Timer mClearPasswordTimer;
+    private static String mSavePassword = DEFAULT_PASSWORD;
 
     private interface CredentialUtil {
         void setCredential(String credential, String savedCredential, int userId)
@@ -367,14 +367,18 @@ public class LockSettingsService extends ILockSettings.Stub {
     }
 
     public void retainPassword(String password) {
-        mSavePassword = password;
-        mClearPasswordTimer = new Timer();
-        mClearPasswordTimer.schedule(new TimerTask() {
-            @Override
-            public void run() {
-                mSavePassword = "default_password";
-            }
-        }, CLEAR_PASSWORD_INTERVAL);
+        if (LockPatternUtils.isDeviceEncryptionEnabled()) {
+            if (password != null)
+                mSavePassword = password;
+            else
+                mSavePassword = DEFAULT_PASSWORD;
+        }
+    }
+
+    public void sanitizePassword() {
+        if (LockPatternUtils.isDeviceEncryptionEnabled()) {
+            mSavePassword = DEFAULT_PASSWORD;
+        }
     }
 
     public String getPassword() {
diff --git a/services/core/java/com/android/server/MountService.java b/services/core/java/com/android/server/MountService.java
index e2babe4..2b12054 100644
--- a/services/core/java/com/android/server/MountService.java
+++ b/services/core/java/com/android/server/MountService.java
@@ -2439,6 +2439,7 @@ class MountService extends IMountService.Stub
         try {
             NativeDaemonEvent event = mCryptConnector.execute("cryptfs", "changepw", CRYPTO_TYPES[type],
                         new SensitiveArg(currentPassword), new SensitiveArg(password));
+            lockSettings.sanitizePassword();
             return Integer.parseInt(event.getMessage());
         } catch (NativeDaemonConnectorException e) {
             // Encryption failed