[MAC rand] Removing persistent storage

Will now calculate the randomized MAC address directly for new wifi
networks.
For existing networks that already have saved randomized MAC address, we
will continue to use the saved MAC.

Bug: 140065828
Test: unit tests before and after factory reset
Test: Verified that new MAC address entries are not populated into
WifiConfigStore.xml
Test: Manually verified calculated MAC addresses are consistent and
valid.
Test: Manually verified that the device secret is persisted over
different builds

Change-Id: Ie216fbaf33e2582ae1a0030c5046b0d4162255d9
Merged-In: I4b4e2cc6fe304d277661c4743e4fb86bb7500f16
(cherry picked from commit I4b4e2cc6fe304d277661c4743e4fb86bb7500f16)

2 files changed, 47 insertions, 1 deletions

diff --git a/tests/wifitests/src/com/android/server/wifi/WifiConfigManagerTest.java b/tests/wifitests/src/com/android/server/wifi/WifiConfigManagerTest.java
index 686b2098d..0badc6fbd 100644
--- a/tests/wifitests/src/com/android/server/wifi/WifiConfigManagerTest.java
+++ b/tests/wifitests/src/com/android/server/wifi/WifiConfigManagerTest.java
@@ -63,6 +63,7 @@ import org.mockito.InOrder;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 import org.mockito.MockitoSession;
+import org.mockito.quality.Strictness;
 
 import java.io.FileDescriptor;
 import java.io.PrintWriter;
@@ -111,6 +112,8 @@ public class WifiConfigManagerTest {
     private static final int TEST_FREQUENCY_1 = 2412;
     private static final int TEST_FREQUENCY_2 = 5180;
     private static final int TEST_FREQUENCY_3 = 5240;
+    private static final MacAddress TEST_RANDOMIZED_MAC =
+            MacAddress.fromString("d2:11:19:34:a5:20");
 
     @Mock private Context mContext;
     @Mock private Clock mClock;
@@ -228,9 +231,13 @@ public class WifiConfigManagerTest {
         // static mocking
         mSession = ExtendedMockito.mockitoSession()
                 .mockStatic(WifiConfigStore.class, withSettings().lenient())
+                .spyStatic(WifiConfigurationUtil.class)
+                .strictness(Strictness.LENIENT)
                 .startMocking();
         when(WifiConfigStore.createUserFiles(anyInt())).thenReturn(mock(List.class));
         when(mTelephonyManager.createForSubscriptionId(anyInt())).thenReturn(mDataTelephonyManager);
+        when(WifiConfigurationUtil.calculatePersistentMacForConfiguration(any(), any()))
+                .thenReturn(TEST_RANDOMIZED_MAC);
     }
 
     /**
@@ -239,7 +246,9 @@ public class WifiConfigManagerTest {
     @After
     public void cleanup() {
         validateMockitoUsage();
-        mSession.finishMocking();
+        if (mSession != null) {
+            mSession.finishMocking();
+        }
     }
 
     /**
@@ -368,6 +377,7 @@ public class WifiConfigManagerTest {
      */
     @Test
     public void testAddingNetworkWithMatchingMacAddressOverridesField() {
+        int prevMappingSize = mWifiConfigManager.getRandomizedMacAddressMappingSize();
         WifiConfiguration openNetwork = WifiConfigurationTestUtil.createOpenNetwork();
         Map<String, String> randomizedMacAddressMapping = new HashMap<>();
         final String randMac = "12:23:34:45:56:67";
@@ -382,6 +392,9 @@ public class WifiConfigManagerTest {
         List<WifiConfiguration> retrievedNetworks =
                 mWifiConfigManager.getConfiguredNetworksWithPasswords();
         assertEquals(randMac, retrievedNetworks.get(0).getRandomizedMacAddress().toString());
+        // Verify that for networks that we already have randomizedMacAddressMapping saved
+        // we are still correctly writing into the WifiConfigStore.
+        assertEquals(prevMappingSize + 1, mWifiConfigManager.getRandomizedMacAddressMappingSize());
     }
 
     /**
@@ -391,6 +404,7 @@ public class WifiConfigManagerTest {
      */
     @Test
     public void testRandomizedMacAddressIsPersistedOverForgetNetwork() {
+        int prevMappingSize = mWifiConfigManager.getRandomizedMacAddressMappingSize();
         // Create and add an open network
         WifiConfiguration openNetwork = WifiConfigurationTestUtil.createOpenNetwork();
         verifyAddNetworkToWifiConfigManager(openNetwork);
@@ -410,6 +424,8 @@ public class WifiConfigManagerTest {
         verifyAddNetworkToWifiConfigManager(openNetwork);
         retrievedNetworks = mWifiConfigManager.getConfiguredNetworksWithPasswords();
         assertEquals(randMac, retrievedNetworks.get(0).getRandomizedMacAddress().toString());
+        // Verify that we are no longer persisting the randomized MAC address with WifiConfigStore.
+        assertEquals(prevMappingSize, mWifiConfigManager.getRandomizedMacAddressMappingSize());
     }
 
     /**
diff --git a/tests/wifitests/src/com/android/server/wifi/WifiConfigurationUtilTest.java b/tests/wifitests/src/com/android/server/wifi/WifiConfigurationUtilTest.java
index c1640ce91..7173dae5b 100644
--- a/tests/wifitests/src/com/android/server/wifi/WifiConfigurationUtilTest.java
+++ b/tests/wifitests/src/com/android/server/wifi/WifiConfigurationUtilTest.java
@@ -25,6 +25,7 @@ import android.net.wifi.WifiConfiguration;
 import android.net.wifi.WifiEnterpriseConfig;
 import android.net.wifi.WifiNetworkSpecifier;
 import android.net.wifi.WifiScanner;
+import android.os.Binder;
 import android.os.PatternMatcher;
 import android.os.UserHandle;
 import android.util.Pair;
@@ -39,6 +40,8 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 
+import javax.crypto.Mac;
+
 /**
  * Unit tests for {@link com.android.server.wifi.WifiConfigurationUtil}.
  */
@@ -961,6 +964,33 @@ public class WifiConfigurationUtilTest {
                 existingConfig, newConfig));
     }
 
+    /**
+     * Verifies that calculatePersistentMacForConfiguration produces persistent, locally generated
+     * MAC addresses that are valid for MAC randomization.
+     */
+    @Test
+    public void testCalculatePersistentMacForConfiguration() {
+        // verify null inputs
+        assertNull(WifiConfigurationUtil.calculatePersistentMacForConfiguration(null, null));
+
+        // test multiple times since there is some randomness involved with hashing
+        int uid = Binder.getCallingUid();
+        for (int i = 0; i < 10; i++) {
+            // Verify that a the MAC address calculated is valid
+            WifiConfiguration config = WifiConfigurationTestUtil.createOpenNetwork();
+            Mac hashFunction = WifiConfigurationUtil.obtainMacRandHashFunction(uid);
+            MacAddress macAddress = WifiConfigurationUtil.calculatePersistentMacForConfiguration(
+                    config, hashFunction);
+            assertTrue(WifiConfiguration.isValidMacAddressForRandomization(macAddress));
+
+            // Verify that the secret used to generate MAC address is persistent
+            Mac hashFunction2 = WifiConfigurationUtil.obtainMacRandHashFunction(uid);
+            MacAddress macAddress2 = WifiConfigurationUtil.calculatePersistentMacForConfiguration(
+                    config, hashFunction2);
+            assertEquals(macAddress, macAddress2);
+        }
+    }
+
     private static class EnterpriseConfig {
         public String eap;
         public String phase2;