On U+ require config_networkWakeupPacketMark/Mask to be 0x80000000

See system/netd/include/Fwmark.h which reserves the bottom 21 bits
of skb->mark for netid, etc... so out of necessity these have to be
in the top 11 bits.

In practice the only values that really make sense are either:
  mark == mask == 0 (disabled)
or (mark == mask) being one of the top 11 available bits, for example:
  mark == mask == 0x80000000 (enabled, using top-most bit)
(only a single bit makes sense, as this is really just a boolean signal,
 and only the topmost is known to be used on any real devices)

Let's just force the use of 0x80000000 for ecosystem consistency.

Bug: 284334830
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I199e9b00de845b3747940426ea6644426ab72e87

service/src/com/android/server/ConnectivityService.java

@@ -317,6 +317,7 @@ import java.io.IOException;
 import java.io.InterruptedIOException;
 import java.io.PrintWriter;
 import java.io.Writer;
+import java.lang.IllegalArgumentException;
 import java.net.Inet4Address;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
@@ -441,6 +442,8 @@ public class ConnectivityService extends IConnectivityManager.Stub
 
     private final Context mContext;
     private final ConnectivityResources mResources;
+    private final int mWakeUpMark;
+    private final int mWakeUpMask;
     // The Context is created for UserHandle.ALL.
     private final Context mUserAllContext;
     private final Dependencies mDeps;
@@ -1610,6 +1613,29 @@ public class ConnectivityService extends IConnectivityManager.Stub
         mCellularRadioTimesharingCapable =
                 mResources.get().getBoolean(R.bool.config_cellular_radio_timesharing_capable);
 
+        int mark = mResources.get().getInteger(R.integer.config_networkWakeupPacketMark);
+        int mask = mResources.get().getInteger(R.integer.config_networkWakeupPacketMask);
+
+        if (SdkLevel.isAtLeastU()) {
+            // U+ default value of both mark & mask, this is the top bit of the skb->mark,
+            // see //system/netd/include/FwMark.h union Fwmark, field ingress_cpu_wakeup
+            final int defaultUMarkMask = 0x80000000;  // u32
+
+            if ((mark == 0) || (mask == 0)) {
+                // simply treat unset/disabled as the default U value
+                mark = defaultUMarkMask;
+                mask = defaultUMarkMask;
+            }
+            if ((mark != defaultUMarkMask) || (mask != defaultUMarkMask)) {
+                // invalid device overlay settings
+                throw new IllegalArgumentException(
+                        "Bad config_networkWakeupPacketMark/Mask " + mark + "/" + mask);
+            }
+        }
+
+        mWakeUpMark = mark;
+        mWakeUpMask = mask;
+
         mNetd = netd;
         mBpfNetMaps = mDeps.getBpfNetMaps(mContext, netd);
         mHandlerThread = mDeps.makeHandlerThread();
@@ -8088,21 +8114,18 @@ public class ConnectivityService extends IConnectivityManager.Stub
             return;
         }
 
-        int mark = mResources.get().getInteger(R.integer.config_networkWakeupPacketMark);
-        int mask = mResources.get().getInteger(R.integer.config_networkWakeupPacketMask);
-
         // Mask/mark of zero will not detect anything interesting.
         // Don't install rules unless both values are nonzero.
-        if (mark == 0 || mask == 0) {
+        if (mWakeUpMark == 0 || mWakeUpMask == 0) {
             return;
         }
 
         final String prefix = makeNflogPrefix(iface, nai.network.getNetworkHandle());
         try {
             if (add) {
-                mNetd.wakeupAddInterface(iface, prefix, mark, mask);
+                mNetd.wakeupAddInterface(iface, prefix, mWakeUpMark, mWakeUpMask);
             } else {
-                mNetd.wakeupDelInterface(iface, prefix, mark, mask);
+                mNetd.wakeupDelInterface(iface, prefix, mWakeUpMark, mWakeUpMask);
             }
         } catch (Exception e) {
             loge("Exception modifying wakeup packet monitoring: " + e);

tests/unit/java/com/android/server/ConnectivityServiceTest.java

@@ -541,8 +541,7 @@ public class ConnectivityServiceTest {
     private static final int TEST_PACKAGE_UID2 = 321;
     private static final int TEST_PACKAGE_UID3 = 456;
 
-    private static final int PACKET_WAKEUP_MASK = 0xffff0000;
+    private static final int PACKET_WAKEUP_MARK_MASK = 0x80000000;
-    private static final int PACKET_WAKEUP_MARK = 0x88880000;
 
     private static final String ALWAYS_ON_PACKAGE = "com.android.test.alwaysonvpn";
 
@@ -1924,9 +1923,9 @@ public class ConnectivityServiceTest {
         doReturn(0).when(mResources).getInteger(R.integer.config_activelyPreferBadWifi);
         doReturn(true).when(mResources)
                 .getBoolean(R.bool.config_cellular_radio_timesharing_capable);
-        doReturn(PACKET_WAKEUP_MASK).when(mResources).getInteger(
+        doReturn(PACKET_WAKEUP_MARK_MASK).when(mResources).getInteger(
                 R.integer.config_networkWakeupPacketMask);
-        doReturn(PACKET_WAKEUP_MARK).when(mResources).getInteger(
+        doReturn(PACKET_WAKEUP_MARK_MASK).when(mResources).getInteger(
                 R.integer.config_networkWakeupPacketMark);
     }
 
@@ -18224,8 +18223,8 @@ public class ConnectivityServiceTest {
 
         final String expectedPrefix = makeNflogPrefix(WIFI_IFNAME,
                 mWiFiAgent.getNetwork().getNetworkHandle());
-        verify(mMockNetd).wakeupAddInterface(WIFI_IFNAME, expectedPrefix, PACKET_WAKEUP_MARK,
+        verify(mMockNetd).wakeupAddInterface(WIFI_IFNAME, expectedPrefix, PACKET_WAKEUP_MARK_MASK,
-                PACKET_WAKEUP_MASK);
+                PACKET_WAKEUP_MARK_MASK);
     }
 
     @Test
@@ -18238,8 +18237,8 @@ public class ConnectivityServiceTest {
         if (mDeps.isAtLeastU()) {
             final String expectedPrefix = makeNflogPrefix(MOBILE_IFNAME,
                     mCellAgent.getNetwork().getNetworkHandle());
-            verify(mMockNetd).wakeupAddInterface(MOBILE_IFNAME, expectedPrefix, PACKET_WAKEUP_MARK,
+            verify(mMockNetd).wakeupAddInterface(MOBILE_IFNAME, expectedPrefix,
-                    PACKET_WAKEUP_MASK);
+                    PACKET_WAKEUP_MARK_MASK, PACKET_WAKEUP_MARK_MASK);
         } else {
             verify(mMockNetd, never()).wakeupAddInterface(eq(MOBILE_IFNAME), anyString(), anyInt(),
                     anyInt());