[BR11] Read data saver status from bpf

Writing data saver status to bpf is supported on Android V or
later devices. Thus, read that from bpf if available.

Test: atest FrameworksNetTests:android.net.connectivity.android.net.BpfNetMapsReaderTest
Test: atest ConnectivityCoverageTests:android.net.connectivity.android.net.ConnectivityManagerTest
Fix: 310801259
Change-Id: Ibd2616328d83f72ee6d2665239c3a44379d1ebf5

framework/src/android/net/BpfNetMapsReader.java

@@ -17,6 +17,9 @@
 package android.net;
 
 import static android.net.BpfNetMapsConstants.CONFIGURATION_MAP_PATH;
+import static android.net.BpfNetMapsConstants.DATA_SAVER_ENABLED;
+import static android.net.BpfNetMapsConstants.DATA_SAVER_ENABLED_KEY;
+import static android.net.BpfNetMapsConstants.DATA_SAVER_ENABLED_MAP_PATH;
 import static android.net.BpfNetMapsConstants.HAPPY_BOX_MATCH;
 import static android.net.BpfNetMapsConstants.PENALTY_BOX_MATCH;
 import static android.net.BpfNetMapsConstants.UID_OWNER_MAP_PATH;
@@ -33,14 +36,15 @@ import android.os.Build;
 import android.os.ServiceSpecificException;
 import android.system.ErrnoException;
 import android.system.Os;
+import android.util.Log;
 
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.modules.utils.build.SdkLevel;
 import com.android.net.module.util.BpfMap;
 import com.android.net.module.util.IBpfMap;
-import com.android.net.module.util.Struct;
 import com.android.net.module.util.Struct.S32;
 import com.android.net.module.util.Struct.U32;
+import com.android.net.module.util.Struct.U8;
 
 /**
  * A helper class to *read* java BpfMaps.
@@ -48,6 +52,8 @@ import com.android.net.module.util.Struct.U32;
  */
 @RequiresApi(Build.VERSION_CODES.TIRAMISU)  // BPF maps were only mainlined in T
 public class BpfNetMapsReader {
+    private static final String TAG = BpfNetMapsReader.class.getSimpleName();
+
     // Locally store the handle of bpf maps. The FileDescriptors are statically cached inside the
     // BpfMap implementation.
 
@@ -57,6 +63,7 @@ public class BpfNetMapsReader {
     // Bpf map to store per uid traffic control configurations.
     // See {@link UidOwnerValue} for more detail.
     private final IBpfMap<S32, UidOwnerValue> mUidOwnerMap;
+    private final IBpfMap<S32, U8> mDataSaverEnabledMap;
     private final Dependencies mDeps;
 
     // Bitmaps for calculating whether a given uid is blocked by firewall chains.
@@ -104,6 +111,7 @@ public class BpfNetMapsReader {
         mDeps = deps;
         mConfigurationMap = mDeps.getConfigurationMap();
         mUidOwnerMap = mDeps.getUidOwnerMap();
+        mDataSaverEnabledMap = mDeps.getDataSaverEnabledMap();
     }
 
     /**
@@ -130,6 +138,16 @@ public class BpfNetMapsReader {
                 throw new IllegalStateException("Cannot open uid owner map", e);
             }
         }
+
+        /** Get the data saver enabled map. */
+        public  IBpfMap<S32, U8> getDataSaverEnabledMap() {
+            try {
+                return new BpfMap<>(DATA_SAVER_ENABLED_MAP_PATH, BpfMap.BPF_F_RDONLY, S32.class,
+                        U8.class);
+            } catch (ErrnoException e) {
+                throw new IllegalStateException("Cannot open data saver enabled map", e);
+            }
+        }
     }
 
     /**
@@ -171,12 +189,12 @@ public class BpfNetMapsReader {
      *                                  cause of the failure.
      */
     public static boolean isChainEnabled(
-            final IBpfMap<Struct.S32, Struct.U32> configurationMap, final int chain) {
+            final IBpfMap<S32, U32> configurationMap, final int chain) {
         throwIfPreT("isChainEnabled is not available on pre-T devices");
 
         final long match = getMatchByFirewallChain(chain);
         try {
-            final Struct.U32 config = configurationMap.getValue(UID_RULES_CONFIGURATION_KEY);
+            final U32 config = configurationMap.getValue(UID_RULES_CONFIGURATION_KEY);
             return (config.val & match) != 0;
         } catch (ErrnoException e) {
             throw new ServiceSpecificException(e.errno,
@@ -195,14 +213,14 @@ public class BpfNetMapsReader {
      * @throws ServiceSpecificException      in case of failure, with an error code indicating the
      *                                       cause of the failure.
      */
-    public static int getUidRule(final IBpfMap<Struct.S32, UidOwnerValue> uidOwnerMap,
+    public static int getUidRule(final IBpfMap<S32, UidOwnerValue> uidOwnerMap,
             final int chain, final int uid) {
         throwIfPreT("getUidRule is not available on pre-T devices");
 
         final long match = getMatchByFirewallChain(chain);
         final boolean isAllowList = isFirewallAllowList(chain);
         try {
-            final UidOwnerValue uidMatch = uidOwnerMap.getValue(new Struct.S32(uid));
+            final UidOwnerValue uidMatch = uidOwnerMap.getValue(new S32(uid));
             final boolean isMatchEnabled = uidMatch != null && (uidMatch.rule & match) != 0;
             return isMatchEnabled == isAllowList ? FIREWALL_RULE_ALLOW : FIREWALL_RULE_DENY;
         } catch (ErrnoException e) {
@@ -249,4 +267,29 @@ public class BpfNetMapsReader {
         if ((uidMatch & HAPPY_BOX_MATCH) != 0) return false;
         return isDataSaverEnabled;
     }
+
+    /**
+     * Get Data Saver enabled or disabled
+     *
+     * @return whether Data Saver is enabled or disabled.
+     * @throws ServiceSpecificException in case of failure, with an error code indicating the
+     *                                  cause of the failure.
+     */
+    public boolean getDataSaverEnabled() {
+        throwIfPreT("getDataSaverEnabled is not available on pre-T devices");
+
+        // Note that this is not expected to be called until V given that it relies on the
+        // counterpart platform solution to set data saver status to bpf.
+        // See {@code NetworkManagementService#setDataSaverModeEnabled}.
+        if (!SdkLevel.isAtLeastV()) {
+            Log.wtf(TAG, "getDataSaverEnabled is not expected to be called on pre-V devices");
+        }
+
+        try {
+            return mDataSaverEnabledMap.getValue(DATA_SAVER_ENABLED_KEY).val == DATA_SAVER_ENABLED;
+        } catch (ErrnoException e) {
+            throw new ServiceSpecificException(e.errno, "Unable to get data saver: "
+                    + Os.strerror(e.errno));
+        }
+    }
 }

framework/src/android/net/ConnectivityManager.java

@@ -83,6 +83,7 @@ import android.util.SparseIntArray;
 
 import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
+import com.android.modules.utils.build.SdkLevel;
 
 import libcore.net.event.NetworkEventDispatcher;
 
@@ -6371,10 +6372,13 @@ public class ConnectivityManager {
         final BpfNetMapsReader reader = BpfNetMapsReader.getInstance();
 
         final boolean isDataSaverEnabled;
-        // TODO: For U-QPR3+ devices, get data saver status from bpf configuration map directly.
+        if (SdkLevel.isAtLeastV()) {
+            isDataSaverEnabled = reader.getDataSaverEnabled();
+        } else {
             final DataSaverStatusTracker dataSaverStatusTracker =
                     DataSaverStatusTracker.getInstance(mContext);
             isDataSaverEnabled = dataSaverStatusTracker.getDataSaverEnabled();
+        }
 
         return reader.isUidNetworkingBlocked(uid, isNetworkMetered, isDataSaverEnabled);
     }

tests/unit/java/android/net/BpfNetMapsReaderTest.kt

@@ -16,6 +16,9 @@
 
 package android.net
 
+import android.net.BpfNetMapsConstants.DATA_SAVER_DISABLED
+import android.net.BpfNetMapsConstants.DATA_SAVER_ENABLED
+import android.net.BpfNetMapsConstants.DATA_SAVER_ENABLED_KEY
 import android.net.BpfNetMapsConstants.DOZABLE_MATCH
 import android.net.BpfNetMapsConstants.HAPPY_BOX_MATCH
 import android.net.BpfNetMapsConstants.PENALTY_BOX_MATCH
@@ -26,6 +29,8 @@ import android.os.Build.VERSION_CODES
 import com.android.net.module.util.IBpfMap
 import com.android.net.module.util.Struct.S32
 import com.android.net.module.util.Struct.U32
+import com.android.net.module.util.Struct.U8
+import com.android.testutils.DevSdkIgnoreRule
 import com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo
 import com.android.testutils.DevSdkIgnoreRunner
 import com.android.testutils.TestBpfMap
@@ -33,6 +38,7 @@ import java.lang.reflect.Modifier
 import kotlin.test.assertEquals
 import kotlin.test.assertFalse
 import kotlin.test.assertTrue
+import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
 
@@ -45,17 +51,24 @@ private const val NO_IIF = 0
 @RunWith(DevSdkIgnoreRunner::class)
 @IgnoreUpTo(VERSION_CODES.S_V2)
 class BpfNetMapsReaderTest {
+    @Rule
+    @JvmField
+    val ignoreRule = DevSdkIgnoreRule()
+
     private val testConfigurationMap: IBpfMap<S32, U32> = TestBpfMap()
     private val testUidOwnerMap: IBpfMap<S32, UidOwnerValue> = TestBpfMap()
+    private val testDataSaverEnabledMap: IBpfMap<S32, U8> = TestBpfMap()
     private val bpfNetMapsReader = BpfNetMapsReader(
-        TestDependencies(testConfigurationMap, testUidOwnerMap))
+        TestDependencies(testConfigurationMap, testUidOwnerMap, testDataSaverEnabledMap))
 
     class TestDependencies(
         private val configMap: IBpfMap<S32, U32>,
-        private val uidOwnerMap: IBpfMap<S32, UidOwnerValue>
+        private val uidOwnerMap: IBpfMap<S32, UidOwnerValue>,
+        private val dataSaverEnabledMap: IBpfMap<S32, U8>
     ) : BpfNetMapsReader.Dependencies() {
         override fun getConfigurationMap() = configMap
         override fun getUidOwnerMap() = uidOwnerMap
+        override fun getDataSaverEnabledMap() = dataSaverEnabledMap
     }
 
     private fun doTestIsChainEnabled(chain: Int) {
@@ -199,4 +212,13 @@ class BpfNetMapsReaderTest {
         assertFalse(isUidNetworkingBlocked(TEST_UID2))
         assertFalse(isUidNetworkingBlocked(TEST_UID3))
     }
+
+    @IgnoreUpTo(VERSION_CODES.UPSIDE_DOWN_CAKE)
+    @Test
+    fun testGetDataSaverEnabled() {
+        testDataSaverEnabledMap.updateEntry(DATA_SAVER_ENABLED_KEY, U8(DATA_SAVER_DISABLED))
+        assertFalse(bpfNetMapsReader.dataSaverEnabled)
+        testDataSaverEnabledMap.updateEntry(DATA_SAVER_ENABLED_KEY, U8(DATA_SAVER_ENABLED))
+        assertTrue(bpfNetMapsReader.dataSaverEnabled)
+    }
 }

tests/unit/java/android/net/ConnectivityManagerTest.java

@@ -90,6 +90,7 @@ import com.android.testutils.DevSdkIgnoreRule;
 import com.android.testutils.DevSdkIgnoreRunner;
 
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.ArgumentCaptor;
@@ -102,6 +103,8 @@ import java.lang.ref.WeakReference;
 @SmallTest
 @DevSdkIgnoreRule.IgnoreUpTo(VERSION_CODES.R)
 public class ConnectivityManagerTest {
+    @Rule
+    public final DevSdkIgnoreRule mIgnoreRule = new DevSdkIgnoreRule();
     private static final int TIMEOUT_MS = 30_000;
     private static final int SHORT_TIMEOUT_MS = 150;
 
@@ -524,6 +527,7 @@ public class ConnectivityManagerTest {
                     + " attempts", ref.get());
     }
 
+    @DevSdkIgnoreRule.IgnoreAfter(VERSION_CODES.UPSIDE_DOWN_CAKE)
     @Test
     public void testDataSaverStatusTracker() {
         mockService(NetworkPolicyManager.class, Context.NETWORK_POLICY_SERVICE, mNpm);