DPM: Propagate StrongBox-related exception

When the caller attempts to generate a key via DevicePolicyManager
(using DevicePolicyManager.generateKeyPair), and specifies that
StrongBox should be used, throw the right exception indicating
StrongBox unavailability - the same one that is thrown if the same
parameters were passed to the KeyStore's key generation method.

This is achieved by catching the StrongBoxUnavailableException in
KeyChain, returning an error code indicating this particular failure
to the DevicePolicyManagerService, which then propagates it by
throwing a service-specific exception with a value indicating
StrongBox unavailability.
The DevicePolicyManager then raises StrongBoxUnavailableException.

Prior to this change the exception propagated from KeyChain would be
a generic failure so the caller would simply get a null result.

Bug: 110882855
Bug: 111183576
Bug: 111322478
Test: atest CtsDevicePolicyManagerTestCases:com.android.cts.devicepolicy.MixedDeviceOwnerTest#testKeyManagement
Change-Id: I9abe3f449b48eb5a960fafbc15c59b9b4ce7a966

diff --git a/core/java/android/app/admin/DevicePolicyManager.java b/core/java/android/app/admin/DevicePolicyManager.java
index bbdc532..cbd8741 100644 (file)
--- a/core/java/android/app/admin/DevicePolicyManager.java
+++ b/core/java/android/app/admin/DevicePolicyManager.java
@@ -72,6 +72,7 @@ import android.security.keystore.AttestationUtils;
 import android.security.keystore.KeyAttestationException;
 import android.security.keystore.KeyGenParameterSpec;
 import android.security.keystore.ParcelableKeyGenParameterSpec;
+import android.security.keystore.StrongBoxUnavailableException;
 import android.service.restrictions.RestrictionsReceiver;
 import android.telephony.TelephonyManager;
 import android.telephony.data.ApnSetting;
@@ -1774,6 +1775,13 @@ public class DevicePolicyManager {
     public static final int ID_TYPE_MEID = 8;
 
     /**
+     * Service-specific error code for {@link #generateKeyPair}:
+     * Indicates the call has failed due to StrongBox unavailability.
+     * @hide
+     */
+    public static final int KEY_GEN_STRONGBOX_UNAVAILABLE = 1;
+
+    /**
      * Specifies that the calling app should be granted access to the installed credentials
      * immediately. Otherwise, access to the credentials will be gated by user approval.
      * For use with {@link #installKeyPair(ComponentName, PrivateKey, Certificate[], String, int)}
@@ -4190,6 +4198,8 @@ public class DevicePolicyManager {
      *         {@code keySpec} does not contain an attestation challenge.
      * @throws UnsupportedOperationException if Device ID attestation was requested but the
      *         underlying hardware does not support it.
+     * @throws StrongBoxUnavailableException if the use of StrongBox for key generation was
+     *         specified in {@code keySpec} but the device does not have one.
      * @see KeyGenParameterSpec.Builder#setAttestationChallenge(byte[])
      */
     public AttestedKeyPair generateKeyPair(@Nullable ComponentName admin,
@@ -4230,6 +4240,15 @@ public class DevicePolicyManager {
         } catch (InterruptedException e) {
             Log.w(TAG, "Interrupted while generating key", e);
             Thread.currentThread().interrupt();
+        } catch (ServiceSpecificException e) {
+            Log.w(TAG, String.format("Key Generation failure: %d", e.errorCode));
+            switch (e.errorCode) {
+                case KEY_GEN_STRONGBOX_UNAVAILABLE:
+                    throw new StrongBoxUnavailableException("No StrongBox for key generation.");
+                default:
+                    throw new RuntimeException(
+                            String.format("Unknown error while generating key: %d", e.errorCode));
+            }
         }
         return null;
     }

diff --git a/keystore/java/android/security/KeyChain.java b/keystore/java/android/security/KeyChain.java
index 030fa60..78dbb6a 100644 (file)
--- a/keystore/java/android/security/KeyChain.java
+++ b/keystore/java/android/security/KeyChain.java
@@ -283,10 +283,16 @@ public final class KeyChain {
     public static final int KEY_GEN_NO_KEYSTORE_PROVIDER = 5;
 
     /**
+     * StrongBox unavailable when calling {@link #generateKeyPair}
+     * @hide
+     */
+    public static final int KEY_GEN_STRONGBOX_UNAVAILABLE = 6;
+
+    /**
      * General failure while calling {@link #generateKeyPair}
      * @hide
      */
-    public static final int KEY_GEN_FAILURE = 6;
+    public static final int KEY_GEN_FAILURE = 7;
 
     /**
      * Successful call to {@link #attestKey}

diff --git a/services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java b/services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java
index 9ef806e..ed4d4db 100644 (file)
--- a/services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java
+++ b/services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java
@@ -5465,7 +5465,14 @@ public class DevicePolicyManagerService extends BaseIDevicePolicyManager {
                 if (generationResult != KeyChain.KEY_GEN_SUCCESS) {
                     Log.e(LOG_TAG, String.format(
                             "KeyChain failed to generate a keypair, error %d.", generationResult));
-                    return false;
+                    switch (generationResult) {
+                        case KeyChain.KEY_GEN_STRONGBOX_UNAVAILABLE:
+                            throw new ServiceSpecificException(
+                                    DevicePolicyManager.KEY_GEN_STRONGBOX_UNAVAILABLE,
+                                    String.format("KeyChain error: %d", generationResult));
+                        default:
+                            return false;
+                    }
                 }
 
                 // Set a grant for the caller here so that when the client calls