Merge "ApfFilter: more precise IPv4 broadcast filter" into nyc-mr1-dev (f7c2ba54) · Commits · e / os / android_frameworks_base

services/net/java/android/net/apf/ApfFilter.java

+36 −20

Original line number	Diff line number	Diff line
		@@ -181,6 +181,7 @@ public class ApfFilter {
		private static final int IPV4_PROTOCOL_OFFSET = ETH_HEADER_LEN + 9;
		private static final int IPV4_DEST_ADDR_OFFSET = ETH_HEADER_LEN + 16;
		private static final int IPV4_ANY_HOST_ADDRESS = 0;
		private static final int IPV4_BROADCAST_ADDRESS = -1; // 255.255.255.255

		private static final int IPV6_NEXT_HEADER_OFFSET = ETH_HEADER_LEN + 6;
		private static final int IPV6_SRC_ADDR_OFFSET = ETH_HEADER_LEN + 8;
		@@ -737,39 +738,54 @@ public class ApfFilter {
		// Here's a basic summary of what the IPv4 filter program does:
		//
		// if filtering multicast (i.e. multicast lock not held):
		// if it's multicast:
		// drop
		// if it's not broadcast:
		// if it's DHCP destined to our MAC:
		// pass
		// if it's not DHCP destined to our MAC:
		// if it's L2 broadcast:
		// drop
		// if it's IPv4 multicast:
		// drop
		// if it's IPv4 broadcast:
		// drop
		// pass

		if (mMulticastFilter) {
		// Check for multicast destination address range
		gen.addLoad8(Register.R0, IPV4_DEST_ADDR_OFFSET);
		gen.addAnd(0xf0);
		gen.addJumpIfR0Equals(0xe0, gen.DROP_LABEL);
		final String skipDhcpv4Filter = "skip_dhcp_v4_filter";

		// Drop all broadcasts besides DHCP addressed to us
		// If not a broadcast packet, pass
		gen.addLoadImmediate(Register.R0, ETH_DEST_ADDR_OFFSET);
		gen.addJumpIfBytesNotEqual(Register.R0, ETH_BROADCAST_MAC_ADDRESS, gen.PASS_LABEL);
		// If not UDP, drop
		// Pass DHCP addressed to us.
		// Check it's UDP.
		gen.addLoad8(Register.R0, IPV4_PROTOCOL_OFFSET);
		gen.addJumpIfR0NotEquals(IPPROTO_UDP, gen.DROP_LABEL);
		// If fragment, drop. This matches the BPF filter installed by the DHCP client.
		gen.addJumpIfR0NotEquals(IPPROTO_UDP, skipDhcpv4Filter);
		// Check it's not a fragment. This matches the BPF filter installed by the DHCP client.
		gen.addLoad16(Register.R0, IPV4_FRAGMENT_OFFSET_OFFSET);
		gen.addJumpIfR0AnyBitsSet(IPV4_FRAGMENT_OFFSET_MASK, gen.DROP_LABEL);
		// If not to DHCP client port, drop
		gen.addJumpIfR0AnyBitsSet(IPV4_FRAGMENT_OFFSET_MASK, skipDhcpv4Filter);
		// Check it's addressed to DHCP client port.
		gen.addLoadFromMemory(Register.R1, gen.IPV4_HEADER_SIZE_MEMORY_SLOT);
		gen.addLoad16Indexed(Register.R0, UDP_DESTINATION_PORT_OFFSET);
		gen.addJumpIfR0NotEquals(DHCP_CLIENT_PORT, gen.DROP_LABEL);
		// If not DHCP to our MAC address, drop
		gen.addJumpIfR0NotEquals(DHCP_CLIENT_PORT, skipDhcpv4Filter);
		// Check it's DHCP to our MAC address.
		gen.addLoadImmediate(Register.R0, DHCP_CLIENT_MAC_OFFSET);
		// NOTE: Relies on R1 containing IPv4 header offset.
		gen.addAddR1();
		gen.addJumpIfBytesNotEqual(Register.R0, mHardwareAddress, gen.DROP_LABEL);
		gen.addJumpIfBytesNotEqual(Register.R0, mHardwareAddress, skipDhcpv4Filter);
		gen.addJump(gen.PASS_LABEL);

		// Drop all multicasts/broadcasts.
		gen.defineLabel(skipDhcpv4Filter);

		// If IPv4 destination address is in multicast range, drop.
		gen.addLoad8(Register.R0, IPV4_DEST_ADDR_OFFSET);
		gen.addAnd(0xf0);
		gen.addJumpIfR0Equals(0xe0, gen.DROP_LABEL);

		// If IPv4 broadcast packet, drop regardless of L2 (b/30231088).
		gen.addLoad32(Register.R0, IPV4_DEST_ADDR_OFFSET);
		gen.addJumpIfR0Equals(IPV4_BROADCAST_ADDRESS, gen.DROP_LABEL);
		// TODO: also filter subnet broadcast address.

		// If L2 broadcast packet, drop.
		gen.addLoadImmediate(Register.R0, ETH_DEST_ADDR_OFFSET);
		gen.addJumpIfBytesNotEqual(Register.R0, ETH_BROADCAST_MAC_ADDRESS, gen.PASS_LABEL);
		gen.addJump(gen.DROP_LABEL);
		}

		// Otherwise, pass

services/tests/servicestests/src/android/net/apf/ApfTest.java

+5 −3

Original line number	Diff line number	Diff line
		@@ -604,7 +604,7 @@ public class ApfTest extends AndroidTestCase {

		public TestApfFilter(IpManager.Callback ipManagerCallback, boolean multicastFilter,
		IpConnectivityLog log) throws Exception {
		super(new ApfCapabilities(2, 1536, ARPHRD_ETHER), NetworkInterface.getByName("lo"),
		super(new ApfCapabilities(2, 1700, ARPHRD_ETHER), NetworkInterface.getByName("lo"),
		ipManagerCallback, multicastFilter, log);
		}

		@@ -721,7 +721,9 @@ public class ApfTest extends AndroidTestCase {
		@LargeTest
		public void testApfFilterIPv4() throws Exception {
		MockIpManagerCallback ipManagerCallback = new MockIpManagerCallback();

		ApfFilter apfFilter = new TestApfFilter(ipManagerCallback, DROP_MULTICAST, mLog);

		byte[] program = ipManagerCallback.getApfProgram();

		// Verify empty packet of 100 zero bytes is passed
		@@ -734,9 +736,9 @@ public class ApfTest extends AndroidTestCase {
		put(packet, IPV4_DEST_ADDR_OFFSET, MOCK_IPV4_ADDR);
		assertPass(program, packet.array());

		// Verify L2 unicast to IPv4 broadcast addresses is passed (b/30231088)
		// Verify L2 unicast to IPv4 broadcast addresses is dropped (b/30231088)
		put(packet, IPV4_DEST_ADDR_OFFSET, IPV4_BROADCAST_ADDRESS);
		assertPass(program, packet.array());
		assertDrop(program, packet.array());
		put(packet, IPV4_DEST_ADDR_OFFSET, MOCK_BROADCAST_IPV4_ADDR);
		assertPass(program, packet.array());