Merge "Keystore 2.0: Remove attestKey from KeyChain." into sc-dev

keystore/java/android/security/IKeyChainService.aidl

@@ -37,8 +37,6 @@ interface IKeyChainService {
     void setUserSelectable(String alias, boolean isUserSelectable);
 
     int generateKeyPair(in String algorithm, in ParcelableKeyGenParameterSpec spec);
-    int attestKey(in String alias, in byte[] challenge, in int[] idAttestationFlags,
-            out KeymasterCertificateChain chain);
     boolean setKeyPairCertificate(String alias, in byte[] userCert, in byte[] certChain);
 
     // APIs used by CertInstaller and DevicePolicyManager

keystore/java/android/security/KeyChain.java

@@ -44,6 +44,8 @@ import android.os.UserManager;
 import android.security.keystore.AndroidKeyStoreProvider;
 import android.security.keystore.KeyPermanentlyInvalidatedException;
 import android.security.keystore.KeyProperties;
+import android.system.keystore2.Domain;
+import android.system.keystore2.KeyDescriptor;
 import android.util.Log;
 
 import com.android.org.conscrypt.TrustedCertificateStore;
@@ -682,6 +684,33 @@ public final class KeyChain {
         return null;
     }
 
+    /**
+     * This prefix is used to disambiguate grant aliase strings from normal key alias strings.
+     * Technically, a key alias string can use the same prefix. However, a collision does not
+     * lead to privilege escalation, because grants are access controlled in the Keystore daemon.
+     * @hide
+     */
+    public static final String GRANT_ALIAS_PREFIX = "ks2_keychain_grant_id:";
+
+    private static KeyDescriptor getGrantDescriptor(String keyid) {
+        KeyDescriptor result = new KeyDescriptor();
+        result.domain = Domain.GRANT;
+        result.blob = null;
+        result.alias = null;
+        try {
+            result.nspace = Long.parseUnsignedLong(
+                    keyid.substring(GRANT_ALIAS_PREFIX.length()), 16 /* radix */);
+        } catch (NumberFormatException e) {
+            return null;
+        }
+        return result;
+    }
+
+    /** @hide */
+    public static String getGrantString(KeyDescriptor key) {
+        return String.format(GRANT_ALIAS_PREFIX + "%016X", key.nspace);
+    }
+
     /** @hide */
     @Nullable @WorkerThread
     public static KeyPair getKeyPair(@NonNull Context context, @NonNull String alias)
@@ -705,11 +734,23 @@ public final class KeyChain {
 
         if (keyId == null) {
             return null;
+        }
+
+        if (AndroidKeyStoreProvider.isKeystore2Enabled()) {
+            try {
+                return android.security.keystore2.AndroidKeyStoreProvider
+                        .loadAndroidKeyStoreKeyPairFromKeystore(
+                                KeyStore2.getInstance(),
+                                getGrantDescriptor(keyId));
+            } catch (UnrecoverableKeyException | KeyPermanentlyInvalidatedException e) {
+                throw new KeyChainException(e);
+            }
         } else {
             try {
                 return AndroidKeyStoreProvider.loadAndroidKeyStoreKeyPairFromKeystore(
                         KeyStore.getInstance(), keyId, KeyStore.UID_SELF);
-            } catch (RuntimeException | UnrecoverableKeyException | KeyPermanentlyInvalidatedException e) {
+            } catch (RuntimeException | UnrecoverableKeyException
+                    | KeyPermanentlyInvalidatedException e) {
                 throw new KeyChainException(e);
             }
         }
@@ -827,11 +868,8 @@ public final class KeyChain {
     @Deprecated
     public static boolean isBoundKeyAlgorithm(
             @NonNull @KeyProperties.KeyAlgorithmEnum String algorithm) {
-        if (!isKeyAlgorithmSupported(algorithm)) {
+        // All supported algorithms are hardware backed. Individual keys may not be.
-            return false;
+        return true;
-        }
-
-        return KeyStore.getInstance().isHardwareBacked(algorithm);
     }
 
     /** @hide */

keystore/java/android/security/keystore2/AndroidKeyStoreProvider.java

@@ -273,10 +273,10 @@ public class AndroidKeyStoreProvider extends Provider {
     /** @hide **/
     @NonNull
     public static KeyPair loadAndroidKeyStoreKeyPairFromKeystore(
-            @NonNull KeyStore2 keyStore, @NonNull String privateKeyAlias, int namespace)
+            @NonNull KeyStore2 keyStore, @NonNull KeyDescriptor descriptor)
             throws UnrecoverableKeyException, KeyPermanentlyInvalidatedException {
         AndroidKeyStoreKey key =
-                loadAndroidKeyStoreKeyFromKeystore(keyStore, privateKeyAlias, namespace);
+                loadAndroidKeyStoreKeyFromKeystore(keyStore, descriptor);
         if (key instanceof AndroidKeyStorePublicKey) {
             AndroidKeyStorePublicKey publicKey = (AndroidKeyStorePublicKey) key;
             return new KeyPair(publicKey, publicKey.getPrivateKey());
@@ -336,7 +336,7 @@ public class AndroidKeyStoreProvider extends Provider {
     @NonNull
     public static AndroidKeyStoreKey loadAndroidKeyStoreKeyFromKeystore(
             @NonNull KeyStore2 keyStore, @NonNull String alias, int namespace)
-            throws UnrecoverableKeyException, KeyPermanentlyInvalidatedException  {
+            throws UnrecoverableKeyException, KeyPermanentlyInvalidatedException {
 
         KeyDescriptor descriptor = new KeyDescriptor();
         if (namespace == KeyProperties.NAMESPACE_APPLICATION) {
@@ -348,6 +348,18 @@ public class AndroidKeyStoreProvider extends Provider {
         }
         descriptor.alias = alias;
         descriptor.blob = null;
+
+        final AndroidKeyStoreKey key = loadAndroidKeyStoreKeyFromKeystore(keyStore, descriptor);
+        if (key instanceof AndroidKeyStorePublicKey) {
+            return ((AndroidKeyStorePublicKey) key).getPrivateKey();
+        } else {
+            return key;
+        }
+    }
+
+    private static AndroidKeyStoreKey loadAndroidKeyStoreKeyFromKeystore(
+            @NonNull KeyStore2 keyStore, @NonNull KeyDescriptor descriptor)
+            throws UnrecoverableKeyException, KeyPermanentlyInvalidatedException {
         KeyEntryResponse response = null;
         try {
             response = keyStore.getKeyEntry(descriptor);
@@ -397,7 +409,7 @@ public class AndroidKeyStoreProvider extends Provider {
                 keymasterAlgorithm == KeymasterDefs.KM_ALGORITHM_EC) {
             return makeAndroidKeyStorePublicKeyFromKeyEntryResponse(descriptor, response.metadata,
                     new KeyStoreSecurityLevel(response.iSecurityLevel),
-                    keymasterAlgorithm).getPrivateKey();
+                    keymasterAlgorithm);
         } else {
             throw new UnrecoverableKeyException("Key algorithm unknown");
         }

services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java

@@ -333,6 +333,7 @@ import com.google.android.collect.Sets;
 
 import org.xmlpull.v1.XmlPullParserException;
 
+import java.io.ByteArrayInputStream;
 import java.io.File;
 import java.io.FileDescriptor;
 import java.io.FileInputStream;
@@ -340,6 +341,9 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.lang.reflect.Constructor;
+import java.security.cert.CertificateException;
+import java.security.cert.CertificateFactory;
+import java.security.cert.X509Certificate;
 import java.text.DateFormat;
 import java.time.LocalDate;
 import java.util.ArrayList;
@@ -5622,7 +5626,7 @@ public class DevicePolicyManagerService extends BaseIDevicePolicyManager {
         // Get attestation flags, if any.
         final int[] attestationUtilsFlags = translateIdAttestationFlags(idAttestationFlags);
         final boolean deviceIdAttestationRequired = attestationUtilsFlags != null;
-        final KeyGenParameterSpec keySpec = parcelableKeySpec.getSpec();
+        KeyGenParameterSpec keySpec = parcelableKeySpec.getSpec();
         final String alias = keySpec.getKeystoreAlias();
 
         Preconditions.checkStringNotEmpty(alias, "Empty alias provided");
@@ -5643,6 +5647,9 @@ public class DevicePolicyManagerService extends BaseIDevicePolicyManager {
                     || (caller.hasPackage() && (isCallerDelegate || isCredentialManagementApp)));
         }
 
+        if (TextUtils.isEmpty(alias)) {
+            throw new IllegalArgumentException("Empty alias provided.");
+        }
         // As the caller will be granted access to the key, ensure no UID was specified, as
         // it will not have the desired effect.
         if (keySpec.getUid() != KeyStore.UID_SELF) {
@@ -5651,19 +5658,26 @@ public class DevicePolicyManagerService extends BaseIDevicePolicyManager {
             return false;
         }
 
+        if (deviceIdAttestationRequired) {
+            if (keySpec.getAttestationChallenge() == null) {
+                throw new IllegalArgumentException(
+                        "Requested Device ID attestation but challenge is empty.");
+            }
+            KeyGenParameterSpec.Builder specBuilder = new KeyGenParameterSpec.Builder(keySpec);
+            specBuilder.setAttestationIds(attestationUtilsFlags);
+            specBuilder.setDevicePropertiesAttestationIncluded(true);
+            keySpec = specBuilder.build();
+        }
+
+        final UserHandle userHandle = mInjector.binderGetCallingUserHandle();
         final long id = mInjector.binderClearCallingIdentity();
         try {
             try (KeyChainConnection keyChainConnection =
-                    KeyChain.bindAsUser(mContext, caller.getUserHandle())) {
+                    KeyChain.bindAsUser(mContext, userHandle)) {
                 IKeyChainService keyChain = keyChainConnection.getService();
 
-                // Copy the provided keySpec, excluding the attestation challenge, which will be
-                // used later for requesting key attestation record.
-                final KeyGenParameterSpec noAttestationSpec = new KeyGenParameterSpec.Builder(
-                        keySpec).setAttestationChallenge(null).build();
-
                 final int generationResult = keyChain.generateKeyPair(algorithm,
-                    new ParcelableKeyGenParameterSpec(noAttestationSpec));
+                        new ParcelableKeyGenParameterSpec(keySpec));
                 if (generationResult != KeyChain.KEY_GEN_SUCCESS) {
                     Log.e(LOG_TAG, String.format(
                             "KeyChain failed to generate a keypair, error %d.", generationResult));
@@ -5672,6 +5686,9 @@ public class DevicePolicyManagerService extends BaseIDevicePolicyManager {
                             throw new ServiceSpecificException(
                                     DevicePolicyManager.KEY_GEN_STRONGBOX_UNAVAILABLE,
                                     String.format("KeyChain error: %d", generationResult));
+                        case KeyChain.KEY_ATTESTATION_CANNOT_ATTEST_IDS:
+                            throw new UnsupportedOperationException(
+                                "Device does not support Device ID attestation.");
                         default:
                             logGenerateKeyPairFailure(caller, isCredentialManagementApp);
                             return false;
@@ -5685,23 +5702,27 @@ public class DevicePolicyManagerService extends BaseIDevicePolicyManager {
                 // that UID.
                 keyChain.setGrant(caller.getUid(), alias, true);
 
-                final byte[] attestationChallenge = keySpec.getAttestationChallenge();
+                try {
-                if (attestationChallenge != null) {
+                    final List<byte[]> encodedCerts = new ArrayList();
-                    final int attestationResult = keyChain.attestKey(
+                    final CertificateFactory certFactory = CertificateFactory.getInstance("X.509");
-                            alias, attestationChallenge, attestationUtilsFlags, attestationChain);
+                    final byte[] certChainBytes = keyChain.getCaCertificates(alias);
-                    if (attestationResult != KeyChain.KEY_ATTESTATION_SUCCESS) {
+                    encodedCerts.add(keyChain.getCertificate(alias));
-                        Log.e(LOG_TAG, String.format(
+                    if (certChainBytes != null) {
-                                "Attestation for %s failed (rc=%d), deleting key.",
+                        final Collection<X509Certificate> certs =
-                                alias, attestationResult));
+                                (Collection<X509Certificate>) certFactory.generateCertificates(
-                        keyChain.removeKeyPair(alias);
+                                    new ByteArrayInputStream(certChainBytes));
-                        if (attestationResult == KeyChain.KEY_ATTESTATION_CANNOT_ATTEST_IDS) {
+                        for (X509Certificate cert : certs) {
-                            throw new UnsupportedOperationException(
+                            encodedCerts.add(cert.getEncoded());
-                                    "Device does not support Device ID attestation.");
                         }
-                        logGenerateKeyPairFailure(caller, isCredentialManagementApp);
-                        return false;
                     }
+
+                    attestationChain.shallowCopyFrom(new KeymasterCertificateChain(encodedCerts));
+                } catch (CertificateException e) {
+                    logGenerateKeyPairFailure(caller, isCredentialManagementApp);
+                    Log.e(LOG_TAG, "While retrieving certificate chain.", e);
+                    return false;
                 }
+
                 DevicePolicyEventLogger
                         .createEvent(DevicePolicyEnums.GENERATE_KEY_PAIR)
                         .setAdmin(caller.getPackageName())