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Merge "Limit the number of routes for performance"

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This commit is contained in:
Chalard Jean
2018-03-30 06:40:29 +00:00
committed by Gerrit Code Review
parent 39d6694208 e0d26f66b0
commit b8a1509d68
2 changed files with 41 additions and 1 deletions
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11
services/core/java/com/android/server/connectivity/Vpn.java
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@@ -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);

31
tests/net/java/com/android/server/connectivity/VpnTest.java
View File

@@ -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);
}
}