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Merge "ApfFilter: more precise IPv4 broadcast filter" into nyc-mr1-dev

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This commit is contained in:
TreeHugger Robot
2016-09-13 03:47:34 +00:00
committed by Android (Google) Code Review
parent 46de5f4917 0dc1d31470
commit f7c2ba5481
2 changed files with 43 additions and 25 deletions
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60
services/net/java/android/net/apf/ApfFilter.java
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@@ -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
final String skipDhcpv4Filter = "skip_dhcp_v4_filter";
// Pass DHCP addressed to us.
// Check it's UDP.
gen.addLoad8(Register.R0, IPV4_PROTOCOL_OFFSET);
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, 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, 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, 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);
// Drop all broadcasts besides DHCP addressed to us
// If not a broadcast packet, pass
// 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);
// If not UDP, drop
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.addLoad16(Register.R0, IPV4_FRAGMENT_OFFSET_OFFSET);
gen.addJumpIfR0AnyBitsSet(IPV4_FRAGMENT_OFFSET_MASK, gen.DROP_LABEL);
// If not to DHCP client port, drop
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.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.addJump(gen.DROP_LABEL);
}
// Otherwise, pass

8
services/tests/servicestests/src/android/net/apf/ApfTest.java
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@@ -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());