Merge "Limit the number of routes for performance" (7d25b9ab) · Commits · e / os / android_frameworks_base

services/core/java/com/android/server/connectivity/Vpn.java

+10 −1

Original line number	Diff line number	Diff line
		@@ -151,6 +151,13 @@ public class Vpn {
		.multiply(BigInteger.valueOf(howManyPercentIsMost))
		.divide(BigInteger.valueOf(100));
		}
		// How many routes to evaluate before bailing and declaring this Vpn should provide
		// the INTERNET capability. This is necessary because computing the adress space is
		// O(n²) and this is running in the system service, so a limit is needed to alleviate
		// the risk of attack.
		// This is taken as a total of IPv4 + IPV6 routes for simplicity, but the algorithm
		// is actually O(n²)+O(n²).
		private static final int MAX_ROUTES_TO_EVALUATE = 150;

		// TODO: create separate trackers for each unique VPN to support
		// automated reconnection
		@@ -862,10 +869,12 @@ public class Vpn {
		*/
		@VisibleForTesting
		static boolean providesRoutesToMostDestinations(LinkProperties lp) {
		final List<RouteInfo> routes = lp.getAllRoutes();
		if (routes.size() > MAX_ROUTES_TO_EVALUATE) return true;
		final Comparator<IpPrefix> prefixLengthComparator = IpPrefix.lengthComparator();
		TreeSet<IpPrefix> ipv4Prefixes = new TreeSet<>(prefixLengthComparator);
		TreeSet<IpPrefix> ipv6Prefixes = new TreeSet<>(prefixLengthComparator);
		for (final RouteInfo route : lp.getAllRoutes()) {
		for (final RouteInfo route : routes) {
		IpPrefix destination = route.getDestination();
		if (destination.isIPv4()) {
		ipv4Prefixes.add(destination);

tests/net/java/com/android/server/connectivity/VpnTest.java

+31 −0

Original line number	Diff line number	Diff line
		@@ -70,6 +70,7 @@ import android.os.Build.VERSION_CODES;
		import android.os.Bundle;
		import android.os.INetworkManagementService;
		import android.os.Looper;
		import android.os.SystemClock;
		import android.os.UserHandle;
		import android.os.UserManager;
		import android.support.test.filters.SmallTest;
		@@ -88,6 +89,8 @@ import org.mockito.InOrder;
		import org.mockito.Mock;
		import org.mockito.MockitoAnnotations;

		import java.net.Inet4Address;
		import java.net.UnknownHostException;
		import java.util.ArrayList;
		import java.util.Arrays;
		import java.util.Collections;
		@@ -639,4 +642,32 @@ public class VpnTest {
		lp.addRoute(new RouteInfo(new IpPrefix("::/1")));
		assertTrue(Vpn.providesRoutesToMostDestinations(lp));
		}

		@Test
		public void testDoesNotLockUpWithTooManyRoutes() {
		final LinkProperties lp = new LinkProperties();
		final byte[] ad = new byte[4];
		// Actually evaluating this many routes under 1500ms is impossible on
		// current hardware and for some time, as the algorithm is O(n²).
		// Make sure the system has a safeguard against this and does not
		// lock up.
		final int MAX_ROUTES = 4000;
		final long MAX_ALLOWED_TIME_MS = 1500;
		for (int i = 0; i < MAX_ROUTES; ++i) {
		ad[0] = (byte)((i >> 24) & 0xFF);
		ad[1] = (byte)((i >> 16) & 0xFF);
		ad[2] = (byte)((i >> 8) & 0xFF);
		ad[3] = (byte)(i & 0xFF);
		try {
		lp.addRoute(new RouteInfo(new IpPrefix(Inet4Address.getByAddress(ad), 32)));
		} catch (UnknownHostException e) {
		// UnknownHostException is only thrown for an address of illegal length,
		// which can't happen in the case above.
		}
		}
		final long start = SystemClock.currentThreadTimeMillis();
		assertTrue(Vpn.providesRoutesToMostDestinations(lp));
		final long end = SystemClock.currentThreadTimeMillis();
		assertTrue(end - start < MAX_ALLOWED_TIME_MS);
		}
		}