Merge changes from topic "vpn_data_accounting"

* changes:
  Move BatteryStats and StatsCompanionService to use NetworkStatsService.
  NetworkStatsService: Fix getDetailedUidStats to take VPNs into account.
  Take all VPN underlying networks into account when migrating traffic for VPN uid.

core/java/android/net/NetworkStats.java

@@ -18,6 +18,7 @@ package android.net;
 
 import static android.os.Process.CLAT_UID;
 
+import android.annotation.NonNull;
 import android.annotation.UnsupportedAppUsage;
 import android.os.Parcel;
 import android.os.Parcelable;
@@ -33,6 +34,7 @@ import libcore.util.EmptyArray;
 import java.io.CharArrayWriter;
 import java.io.PrintWriter;
 import java.util.Arrays;
+import java.util.function.Predicate;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Objects;
@@ -993,23 +995,33 @@ public class NetworkStats implements Parcelable {
         if (limitUid == UID_ALL && limitTag == TAG_ALL && limitIfaces == INTERFACES_ALL) {
             return;
         }
+        filter(e -> (limitUid == UID_ALL || limitUid == e.uid)
+            && (limitTag == TAG_ALL || limitTag == e.tag)
+            && (limitIfaces == INTERFACES_ALL
+                    || ArrayUtils.contains(limitIfaces, e.iface)));
+    }
 
+    /**
+     * Only keep entries with {@link #set} value less than {@link #SET_DEBUG_START}.
+     *
+     * <p>This mutates the original structure in place.
+     */
+    public void filterDebugEntries() {
+        filter(e -> e.set < SET_DEBUG_START);
+    }
+
+    private void filter(Predicate<Entry> predicate) {
         Entry entry = new Entry();
         int nextOutputEntry = 0;
         for (int i = 0; i < size; i++) {
             entry = getValues(i, entry);
-            final boolean matches =
+            if (predicate.test(entry)) {
-                    (limitUid == UID_ALL || limitUid == entry.uid)
+                if (nextOutputEntry != i) {
-                    && (limitTag == TAG_ALL || limitTag == entry.tag)
+                    setValues(nextOutputEntry, entry);
-                    && (limitIfaces == INTERFACES_ALL
+                }
-                            || ArrayUtils.contains(limitIfaces, entry.iface));
-
-            if (matches) {
-                setValues(nextOutputEntry, entry);
                 nextOutputEntry++;
             }
         }
-
         size = nextOutputEntry;
     }
 
@@ -1175,133 +1187,217 @@ public class NetworkStats implements Parcelable {
     /**
      * VPN accounting. Move some VPN's underlying traffic to other UIDs that use tun0 iface.
      *
-     * This method should only be called on delta NetworkStats. Do not call this method on a
+     * <p>This method should only be called on delta NetworkStats. Do not call this method on a
-     * snapshot {@link NetworkStats} object because the tunUid and/or the underlyingIface may
+     * snapshot {@link NetworkStats} object because the tunUid and/or the underlyingIface may change
-     * change over time.
+     * over time.
      *
-     * This method performs adjustments for one active VPN package and one VPN iface at a time.
+     * <p>This method performs adjustments for one active VPN package and one VPN iface at a time.
-     *
-     * It is possible for the VPN software to use multiple underlying networks. This method
-     * only migrates traffic for the primary underlying network.
      *
      * @param tunUid uid of the VPN application
      * @param tunIface iface of the vpn tunnel
-     * @param underlyingIface the primary underlying network iface used by the VPN application
+     * @param underlyingIfaces underlying network ifaces used by the VPN application
-     * @return true if it successfully adjusts the accounting for VPN, false otherwise
      */
-    public boolean migrateTun(int tunUid, String tunIface, String underlyingIface) {
+    public void migrateTun(int tunUid, @NonNull String tunIface,
-        Entry tunIfaceTotal = new Entry();
+            @NonNull String[] underlyingIfaces) {
-        Entry underlyingIfaceTotal = new Entry();
+        // Combined usage by all apps using VPN.
+        final Entry tunIfaceTotal = new Entry();
+        // Usage by VPN, grouped by its {@code underlyingIfaces}.
+        final Entry[] perInterfaceTotal = new Entry[underlyingIfaces.length];
+        // Usage by VPN, summed across all its {@code underlyingIfaces}.
+        final Entry underlyingIfacesTotal = new Entry();
 
-        tunAdjustmentInit(tunUid, tunIface, underlyingIface, tunIfaceTotal, underlyingIfaceTotal);
+        for (int i = 0; i < perInterfaceTotal.length; i++) {
+            perInterfaceTotal[i] = new Entry();
+        }
 
-        // If tunIface < underlyingIface, it leaves the overhead traffic in the VPN app.
+        tunAdjustmentInit(tunUid, tunIface, underlyingIfaces, tunIfaceTotal, perInterfaceTotal,
-        // If tunIface > underlyingIface, the VPN app doesn't get credit for data compression.
+                underlyingIfacesTotal);
+
+        // If tunIface < underlyingIfacesTotal, it leaves the overhead traffic in the VPN app.
+        // If tunIface > underlyingIfacesTotal, the VPN app doesn't get credit for data compression.
         // Negative stats should be avoided.
-        Entry pool = tunGetPool(tunIfaceTotal, underlyingIfaceTotal);
+        final Entry[] moved =
-        if (pool.isEmpty()) {
+                addTrafficToApplications(tunUid, tunIface, underlyingIfaces, tunIfaceTotal,
-            return true;
+                        perInterfaceTotal, underlyingIfacesTotal);
-        }
+        deductTrafficFromVpnApp(tunUid, underlyingIfaces, moved);
-        Entry moved =
-                addTrafficToApplications(tunUid, tunIface, underlyingIface, tunIfaceTotal, pool);
-        deductTrafficFromVpnApp(tunUid, underlyingIface, moved);
-
-        if (!moved.isEmpty()) {
-            Slog.wtf(TAG, "Failed to deduct underlying network traffic from VPN package. Moved="
-                    + moved);
-            return false;
-        }
-        return true;
     }
 
     /**
      * Initializes the data used by the migrateTun() method.
      *
-     * This is the first pass iteration which does the following work:
+     * <p>This is the first pass iteration which does the following work:
-     * (1) Adds up all the traffic through the tunUid's underlyingIface
+     *
-     *     (both foreground and background).
+     * <ul>
-     * (2) Adds up all the traffic through tun0 excluding traffic from the vpn app itself.
+     *   <li>Adds up all the traffic through the tunUid's underlyingIfaces (both foreground and
+     *       background).
+     *   <li>Adds up all the traffic through tun0 excluding traffic from the vpn app itself.
+     * </ul>
+     *
+     * @param tunUid uid of the VPN application
+     * @param tunIface iface of the vpn tunnel
+     * @param underlyingIfaces underlying network ifaces used by the VPN application
+     * @param tunIfaceTotal output parameter; combined data usage by all apps using VPN
+     * @param perInterfaceTotal output parameter; data usage by VPN app, grouped by its {@code
+     *     underlyingIfaces}
+     * @param underlyingIfacesTotal output parameter; data usage by VPN, summed across all of its
+     *     {@code underlyingIfaces}
      */
-    private void tunAdjustmentInit(int tunUid, String tunIface, String underlyingIface,
+    private void tunAdjustmentInit(int tunUid, @NonNull String tunIface,
-            Entry tunIfaceTotal, Entry underlyingIfaceTotal) {
+            @NonNull String[] underlyingIfaces, @NonNull Entry tunIfaceTotal,
-        Entry recycle = new Entry();
+            @NonNull Entry[] perInterfaceTotal, @NonNull Entry underlyingIfacesTotal) {
+        final Entry recycle = new Entry();
         for (int i = 0; i < size; i++) {
             getValues(i, recycle);
             if (recycle.uid == UID_ALL) {
                 throw new IllegalStateException(
                         "Cannot adjust VPN accounting on an iface aggregated NetworkStats.");
-            } if (recycle.set == SET_DBG_VPN_IN || recycle.set == SET_DBG_VPN_OUT) {
+            }
+            if (recycle.set == SET_DBG_VPN_IN || recycle.set == SET_DBG_VPN_OUT) {
                 throw new IllegalStateException(
                         "Cannot adjust VPN accounting on a NetworkStats containing SET_DBG_VPN_*");
             }
-
+            if (recycle.tag != TAG_NONE) {
-            if (recycle.uid == tunUid && recycle.tag == TAG_NONE
+                // TODO(b/123666283): Take all tags for tunUid into account.
-                    && Objects.equals(underlyingIface, recycle.iface)) {
+                continue;
-                underlyingIfaceTotal.add(recycle);
             }
 
-            if (recycle.uid != tunUid && recycle.tag == TAG_NONE
+            if (recycle.uid == tunUid) {
-                    && Objects.equals(tunIface, recycle.iface)) {
+                // Add up traffic through tunUid's underlying interfaces.
+                for (int j = 0; j < underlyingIfaces.length; j++) {
+                    if (Objects.equals(underlyingIfaces[j], recycle.iface)) {
+                        perInterfaceTotal[j].add(recycle);
+                        underlyingIfacesTotal.add(recycle);
+                        break;
+                    }
+                }
+            } else if (tunIface.equals(recycle.iface)) {
                 // Add up all tunIface traffic excluding traffic from the vpn app itself.
                 tunIfaceTotal.add(recycle);
             }
         }
     }
 
-    private static Entry tunGetPool(Entry tunIfaceTotal, Entry underlyingIfaceTotal) {
+    /**
-        Entry pool = new Entry();
+     * Distributes traffic across apps that are using given {@code tunIface}, and returns the total
-        pool.rxBytes = Math.min(tunIfaceTotal.rxBytes, underlyingIfaceTotal.rxBytes);
+     * traffic that should be moved off of {@code tunUid} grouped by {@code underlyingIfaces}.
-        pool.rxPackets = Math.min(tunIfaceTotal.rxPackets, underlyingIfaceTotal.rxPackets);
+     *
-        pool.txBytes = Math.min(tunIfaceTotal.txBytes, underlyingIfaceTotal.txBytes);
+     * @param tunUid uid of the VPN application
-        pool.txPackets = Math.min(tunIfaceTotal.txPackets, underlyingIfaceTotal.txPackets);
+     * @param tunIface iface of the vpn tunnel
-        pool.operations = Math.min(tunIfaceTotal.operations, underlyingIfaceTotal.operations);
+     * @param underlyingIfaces underlying network ifaces used by the VPN application
-        return pool;
+     * @param tunIfaceTotal combined data usage across all apps using {@code tunIface}
-    }
+     * @param perInterfaceTotal data usage by VPN app, grouped by its {@code underlyingIfaces}
+     * @param underlyingIfacesTotal data usage by VPN, summed across all of its {@code
+     *     underlyingIfaces}
+     */
+    private Entry[] addTrafficToApplications(int tunUid, @NonNull String tunIface,
+            @NonNull String[] underlyingIfaces, @NonNull Entry tunIfaceTotal,
+            @NonNull Entry[] perInterfaceTotal, @NonNull Entry underlyingIfacesTotal) {
+        // Traffic that should be moved off of each underlying interface for tunUid (see
+        // deductTrafficFromVpnApp below).
+        final Entry[] moved = new Entry[underlyingIfaces.length];
+        for (int i = 0; i < underlyingIfaces.length; i++) {
+            moved[i] = new Entry();
+        }
 
-    private Entry addTrafficToApplications(int tunUid, String tunIface, String underlyingIface,
+        final Entry tmpEntry = new Entry();
-            Entry tunIfaceTotal, Entry pool) {
-        Entry moved = new Entry();
-        Entry tmpEntry = new Entry();
-        tmpEntry.iface = underlyingIface;
         for (int i = 0; i < size; i++) {
-            // the vpn app is excluded from the redistribution but all moved traffic will be
+            if (!Objects.equals(iface[i], tunIface)) {
-            // deducted from the vpn app (see deductTrafficFromVpnApp below).
+                // Consider only entries that go onto the VPN interface.
-            if (Objects.equals(iface[i], tunIface) && uid[i] != tunUid) {
+                continue;
-                if (tunIfaceTotal.rxBytes > 0) {
+            }
-                    tmpEntry.rxBytes = pool.rxBytes * rxBytes[i] / tunIfaceTotal.rxBytes;
+            if (uid[i] == tunUid) {
-                } else {
+                // Exclude VPN app from the redistribution, as it can choose to create packet
-                    tmpEntry.rxBytes = 0;
+                // streams by writing to itself.
-                }
+                continue;
-                if (tunIfaceTotal.rxPackets > 0) {
+            }
-                    tmpEntry.rxPackets = pool.rxPackets * rxPackets[i] / tunIfaceTotal.rxPackets;
+            tmpEntry.uid = uid[i];
-                } else {
+            tmpEntry.tag = tag[i];
-                    tmpEntry.rxPackets = 0;
+            tmpEntry.metered = metered[i];
-                }
+            tmpEntry.roaming = roaming[i];
-                if (tunIfaceTotal.txBytes > 0) {
+            tmpEntry.defaultNetwork = defaultNetwork[i];
-                    tmpEntry.txBytes = pool.txBytes * txBytes[i] / tunIfaceTotal.txBytes;
+
-                } else {
+            // In a first pass, compute each UID's total share of data across all underlyingIfaces.
-                    tmpEntry.txBytes = 0;
+            // This is computed on the basis of the share of each UID's usage over tunIface.
-                }
+            // TODO: Consider refactoring first pass into a separate helper method.
-                if (tunIfaceTotal.txPackets > 0) {
+            long totalRxBytes = 0;
-                    tmpEntry.txPackets = pool.txPackets * txPackets[i] / tunIfaceTotal.txPackets;
+            if (tunIfaceTotal.rxBytes > 0) {
-                } else {
+                // Note - The multiplication below should not overflow since NetworkStatsService
-                    tmpEntry.txPackets = 0;
+                // processes this every time device has transmitted/received amount equivalent to
-                }
+                // global threshold alert (~ 2MB) across all interfaces.
-                if (tunIfaceTotal.operations > 0) {
+                final long rxBytesAcrossUnderlyingIfaces =
-                    tmpEntry.operations =
+                        underlyingIfacesTotal.rxBytes * rxBytes[i] / tunIfaceTotal.rxBytes;
-                            pool.operations * operations[i] / tunIfaceTotal.operations;
+                // app must not be blamed for more than it consumed on tunIface
-                } else {
+                totalRxBytes = Math.min(rxBytes[i], rxBytesAcrossUnderlyingIfaces);
-                    tmpEntry.operations = 0;
+            }
-                }
+            long totalRxPackets = 0;
-                tmpEntry.uid = uid[i];
+            if (tunIfaceTotal.rxPackets > 0) {
-                tmpEntry.tag = tag[i];
+                final long rxPacketsAcrossUnderlyingIfaces =
+                        underlyingIfacesTotal.rxPackets * rxPackets[i] / tunIfaceTotal.rxPackets;
+                totalRxPackets = Math.min(rxPackets[i], rxPacketsAcrossUnderlyingIfaces);
+            }
+            long totalTxBytes = 0;
+            if (tunIfaceTotal.txBytes > 0) {
+                final long txBytesAcrossUnderlyingIfaces =
+                        underlyingIfacesTotal.txBytes * txBytes[i] / tunIfaceTotal.txBytes;
+                totalTxBytes = Math.min(txBytes[i], txBytesAcrossUnderlyingIfaces);
+            }
+            long totalTxPackets = 0;
+            if (tunIfaceTotal.txPackets > 0) {
+                final long txPacketsAcrossUnderlyingIfaces =
+                        underlyingIfacesTotal.txPackets * txPackets[i] / tunIfaceTotal.txPackets;
+                totalTxPackets = Math.min(txPackets[i], txPacketsAcrossUnderlyingIfaces);
+            }
+            long totalOperations = 0;
+            if (tunIfaceTotal.operations > 0) {
+                final long operationsAcrossUnderlyingIfaces =
+                        underlyingIfacesTotal.operations * operations[i] / tunIfaceTotal.operations;
+                totalOperations = Math.min(operations[i], operationsAcrossUnderlyingIfaces);
+            }
+            // In a second pass, distribute these values across interfaces in the proportion that
+            // each interface represents of the total traffic of the underlying interfaces.
+            for (int j = 0; j < underlyingIfaces.length; j++) {
+                tmpEntry.iface = underlyingIfaces[j];
+                tmpEntry.rxBytes = 0;
+                // Reset 'set' to correct value since it gets updated when adding debug info below.
                 tmpEntry.set = set[i];
-                tmpEntry.metered = metered[i];
+                if (underlyingIfacesTotal.rxBytes > 0) {
-                tmpEntry.roaming = roaming[i];
+                    tmpEntry.rxBytes =
-                tmpEntry.defaultNetwork = defaultNetwork[i];
+                            totalRxBytes
+                                    * perInterfaceTotal[j].rxBytes
+                                    / underlyingIfacesTotal.rxBytes;
+                }
+                tmpEntry.rxPackets = 0;
+                if (underlyingIfacesTotal.rxPackets > 0) {
+                    tmpEntry.rxPackets =
+                            totalRxPackets
+                                    * perInterfaceTotal[j].rxPackets
+                                    / underlyingIfacesTotal.rxPackets;
+                }
+                tmpEntry.txBytes = 0;
+                if (underlyingIfacesTotal.txBytes > 0) {
+                    tmpEntry.txBytes =
+                            totalTxBytes
+                                    * perInterfaceTotal[j].txBytes
+                                    / underlyingIfacesTotal.txBytes;
+                }
+                tmpEntry.txPackets = 0;
+                if (underlyingIfacesTotal.txPackets > 0) {
+                    tmpEntry.txPackets =
+                            totalTxPackets
+                                    * perInterfaceTotal[j].txPackets
+                                    / underlyingIfacesTotal.txPackets;
+                }
+                tmpEntry.operations = 0;
+                if (underlyingIfacesTotal.operations > 0) {
+                    tmpEntry.operations =
+                            totalOperations
+                                    * perInterfaceTotal[j].operations
+                                    / underlyingIfacesTotal.operations;
+                }
+
                 combineValues(tmpEntry);
                 if (tag[i] == TAG_NONE) {
-                    moved.add(tmpEntry);
+                    moved[j].add(tmpEntry);
                     // Add debug info
                     tmpEntry.set = SET_DBG_VPN_IN;
                     combineValues(tmpEntry);
@@ -1311,38 +1407,45 @@ public class NetworkStats implements Parcelable {
         return moved;
     }
 
-    private void deductTrafficFromVpnApp(int tunUid, String underlyingIface, Entry moved) {
+    private void deductTrafficFromVpnApp(
-        // Add debug info
+            int tunUid,
-        moved.uid = tunUid;
+            @NonNull String[] underlyingIfaces,
-        moved.set = SET_DBG_VPN_OUT;
+            @NonNull Entry[] moved) {
-        moved.tag = TAG_NONE;
+        for (int i = 0; i < underlyingIfaces.length; i++) {
-        moved.iface = underlyingIface;
+            // Add debug info
-        moved.metered = METERED_ALL;
+            moved[i].uid = tunUid;
-        moved.roaming = ROAMING_ALL;
+            moved[i].set = SET_DBG_VPN_OUT;
-        moved.defaultNetwork = DEFAULT_NETWORK_ALL;
+            moved[i].tag = TAG_NONE;
-        combineValues(moved);
+            moved[i].iface = underlyingIfaces[i];
+            moved[i].metered = METERED_ALL;
+            moved[i].roaming = ROAMING_ALL;
+            moved[i].defaultNetwork = DEFAULT_NETWORK_ALL;
+            combineValues(moved[i]);
 
-        // Caveat: if the vpn software uses tag, the total tagged traffic may be greater than
+            // Caveat: if the vpn software uses tag, the total tagged traffic may be greater than
-        // the TAG_NONE traffic.
+            // the TAG_NONE traffic.
-        //
+            //
-        // Relies on the fact that the underlying traffic only has state ROAMING_NO and METERED_NO,
+            // Relies on the fact that the underlying traffic only has state ROAMING_NO and
-        // which should be the case as it comes directly from the /proc file. We only blend in the
+            // METERED_NO, which should be the case as it comes directly from the /proc file.
-        // roaming data after applying these adjustments, by checking the NetworkIdentity of the
+            // We only blend in the roaming data after applying these adjustments, by checking the
-        // underlying iface.
+            // NetworkIdentity of the underlying iface.
-        int idxVpnBackground = findIndex(underlyingIface, tunUid, SET_DEFAULT, TAG_NONE,
+            final int idxVpnBackground = findIndex(underlyingIfaces[i], tunUid, SET_DEFAULT,
-                METERED_NO, ROAMING_NO, DEFAULT_NETWORK_NO);
+                            TAG_NONE, METERED_NO, ROAMING_NO, DEFAULT_NETWORK_NO);
-        if (idxVpnBackground != -1) {
+            if (idxVpnBackground != -1) {
-            tunSubtract(idxVpnBackground, this, moved);
+                // Note - tunSubtract also updates moved[i]; whatever traffic that's left is removed
-        }
+                // from foreground usage.
+                tunSubtract(idxVpnBackground, this, moved[i]);
+            }
 
-        int idxVpnForeground = findIndex(underlyingIface, tunUid, SET_FOREGROUND, TAG_NONE,
+            final int idxVpnForeground = findIndex(underlyingIfaces[i], tunUid, SET_FOREGROUND,
-                METERED_NO, ROAMING_NO, DEFAULT_NETWORK_NO);
+                            TAG_NONE, METERED_NO, ROAMING_NO, DEFAULT_NETWORK_NO);
-        if (idxVpnForeground != -1) {
+            if (idxVpnForeground != -1) {
-            tunSubtract(idxVpnForeground, this, moved);
+                tunSubtract(idxVpnForeground, this, moved[i]);
+            }
         }
     }
 
-    private static void tunSubtract(int i, NetworkStats left, Entry right) {
+    private static void tunSubtract(int i, @NonNull NetworkStats left, @NonNull Entry right) {
         long rxBytes = Math.min(left.rxBytes[i], right.rxBytes);
         left.rxBytes[i] -= rxBytes;
         right.rxBytes -= rxBytes;

core/java/com/android/internal/net/NetworkStatsFactory.java

@@ -256,6 +256,11 @@ public class NetworkStatsFactory {
         return stats;
     }
 
+    /**
+     * @deprecated Use NetworkStatsService#getDetailedUidStats which also accounts for
+     * VPN traffic
+     */
+    @Deprecated
     public NetworkStats readNetworkStatsDetail() throws IOException {
         return readNetworkStatsDetail(UID_ALL, null, TAG_ALL, null);
     }

services/core/java/com/android/server/net/NetworkStatsRecorder.java

@@ -41,10 +41,10 @@ import com.android.internal.net.VpnInfo;
 import com.android.internal.util.FileRotator;
 import com.android.internal.util.IndentingPrintWriter;
 
-import libcore.io.IoUtils;
-
 import com.google.android.collect.Sets;
 
+import libcore.io.IoUtils;
+
 import java.io.ByteArrayOutputStream;
 import java.io.DataOutputStream;
 import java.io.File;
@@ -234,7 +234,7 @@ public class NetworkStatsRecorder {
 
         if (vpnArray != null) {
             for (VpnInfo info : vpnArray) {
-                delta.migrateTun(info.ownerUid, info.vpnIface, info.primaryUnderlyingIface);
+                delta.migrateTun(info.ownerUid, info.vpnIface, info.underlyingIfaces);
             }
         }
 

services/core/java/com/android/server/net/NetworkStatsService.java

@@ -292,6 +292,22 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     /** Data layer operation counters for splicing into other structures. */
     private NetworkStats mUidOperations = new NetworkStats(0L, 10);
 
+    /**
+     * Snapshot containing most recent network stats for all UIDs across all interfaces and tags
+     * since boot.
+     *
+     * <p>Maintains migrated VPN stats which are result of performing TUN migration on {@link
+     * #mLastUidDetailSnapshot}.
+     */
+    @GuardedBy("mStatsLock")
+    private NetworkStats mTunAdjustedStats;
+    /**
+     * Used by {@link #mTunAdjustedStats} to migrate VPN traffic over delta between this snapshot
+     * and latest snapshot.
+     */
+    @GuardedBy("mStatsLock")
+    private NetworkStats mLastUidDetailSnapshot;
+
     /** Must be set in factory by calling #setHandler. */
     private Handler mHandler;
     private Handler.Callback mHandlerCallback;
@@ -805,15 +821,39 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     @Override
     public NetworkStats getDetailedUidStats(String[] requiredIfaces) {
         try {
+            // Get the latest snapshot from NetworkStatsFactory.
+            // TODO: Querying for INTERFACES_ALL may incur performance penalty. Consider restricting
+            // this to limited set of ifaces.
+            NetworkStats uidDetailStats = getNetworkStatsUidDetail(INTERFACES_ALL);
+
+            // Migrate traffic from VPN UID over delta and update mTunAdjustedStats.
+            NetworkStats result;
+            synchronized (mStatsLock) {
+                migrateTunTraffic(uidDetailStats, mVpnInfos);
+                result = mTunAdjustedStats.clone();
+            }
+
+            // Apply filter based on ifacesToQuery.
             final String[] ifacesToQuery =
                     NetworkStatsFactory.augmentWithStackedInterfaces(requiredIfaces);
-            return getNetworkStatsUidDetail(ifacesToQuery);
+            result.filter(UID_ALL, ifacesToQuery, TAG_ALL);
+            return result;
         } catch (RemoteException e) {
             Log.wtf(TAG, "Error compiling UID stats", e);
             return new NetworkStats(0L, 0);
         }
     }
 
+    @VisibleForTesting
+    NetworkStats getTunAdjustedStats() {
+        synchronized (mStatsLock) {
+            if (mTunAdjustedStats == null) {
+                return null;
+            }
+            return mTunAdjustedStats.clone();
+        }
+    }
+
     @Override
     public String[] getMobileIfaces() {
         return mMobileIfaces;
@@ -1288,6 +1328,34 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         // a race condition between the service handler thread and the observer's
         mStatsObservers.updateStats(xtSnapshot, uidSnapshot, new ArrayMap<>(mActiveIfaces),
                 new ArrayMap<>(mActiveUidIfaces), vpnArray, currentTime);
+
+        migrateTunTraffic(uidSnapshot, vpnArray);
+    }
+
+    /**
+     * Updates {@link #mTunAdjustedStats} with the delta containing traffic migrated off of VPNs.
+     */
+    @GuardedBy("mStatsLock")
+    private void migrateTunTraffic(NetworkStats uidDetailStats, VpnInfo[] vpnInfoArray) {
+        if (mTunAdjustedStats == null) {
+            // Either device booted or system server restarted, hence traffic cannot be migrated
+            // correctly without knowing the past state of VPN's underlying networks.
+            mTunAdjustedStats = uidDetailStats;
+            mLastUidDetailSnapshot = uidDetailStats;
+            return;
+        }
+        // Migrate delta traffic from VPN to other apps.
+        NetworkStats delta = uidDetailStats.subtract(mLastUidDetailSnapshot);
+        for (VpnInfo info : vpnInfoArray) {
+            delta.migrateTun(info.ownerUid, info.vpnIface, info.underlyingIfaces);
+        }
+        // Filter out debug entries as that may lead to over counting.
+        delta.filterDebugEntries();
+        // Update #mTunAdjustedStats with migrated delta.
+        mTunAdjustedStats.combineAllValues(delta);
+        mTunAdjustedStats.setElapsedRealtime(uidDetailStats.getElapsedRealtime());
+        // Update last snapshot.
+        mLastUidDetailSnapshot = uidDetailStats;
     }
 
     /**