Merge "Add APF code to drop ARP IPv4 requests not for us" into nyc-dev (cd404a2f) · Commits · e / os / android_frameworks_base

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

+89 −7

Original line number	Diff line number	Diff line
		@@ -18,6 +18,7 @@ package android.net.apf;

		import static android.system.OsConstants.*;

		import android.net.LinkProperties;
		import android.net.NetworkUtils;
		import android.net.apf.ApfGenerator;
		import android.net.apf.ApfGenerator.IllegalInstructionException;
		@@ -136,6 +137,16 @@ public class ApfFilter {
		// NOTE: this must be added to the IPv4 header length in IPV4_HEADER_SIZE_MEMORY_SLOT
		private static final int DHCP_CLIENT_MAC_OFFSET = ETH_HEADER_LEN + UDP_HEADER_LEN + 28;

		private static int ARP_HEADER_OFFSET = ETH_HEADER_LEN;
		private static final byte[] ARP_IPV4_REQUEST_HEADER = new byte[]{
		0, 1, // Hardware type: Ethernet (1)
		8, 0, // Protocol type: IP (0x0800)
		6, // Hardware size: 6
		4, // Protocol size: 4
		0, 1 // Opcode: request (1)
		};
		private static int ARP_TARGET_IP_ADDRESS_OFFSET = ETH_HEADER_LEN + 24;

		private final ApfCapabilities mApfCapabilities;
		private final IpManager.Callback mIpManagerCallback;
		private final NetworkInterface mNetworkInterface;
		@@ -145,6 +156,9 @@ public class ApfFilter {
		private long mUniqueCounter;
		@GuardedBy("this")
		private boolean mMulticastFilter;
		// Our IPv4 address, if we have just one, otherwise null.
		@GuardedBy("this")
		private byte[] mIPv4Address;

		private ApfFilter(ApfCapabilities apfCapabilities, NetworkInterface networkInterface,
		IpManager.Callback ipManagerCallback, boolean multicastFilter) {
		@@ -506,6 +520,33 @@ public class ApfFilter {
		@GuardedBy("this")
		private byte[] mLastInstalledProgram;

		/**
		* Generate filter code to process ARP packets. Execution of this code ends in either the
		* DROP_LABEL or PASS_LABEL and does not fall off the end.
		* Preconditions:
		* - Packet being filtered is ARP
		*/
		@GuardedBy("this")
		private void generateArpFilterLocked(ApfGenerator gen) throws IllegalInstructionException {
		// Here's a basic summary of what the ARP filter program does:
		//
		// if it's not an ARP IPv4 request:
		// pass
		// if it's not a request for our IPv4 address:
		// drop
		// pass

		// if it's not an ARP IPv4 request, pass
		gen.addLoadImmediate(Register.R0, ARP_HEADER_OFFSET);
		gen.addJumpIfBytesNotEqual(Register.R0, ARP_IPV4_REQUEST_HEADER, gen.PASS_LABEL);
		// if it's not a request for our IPv4 address, drop
		gen.addLoadImmediate(Register.R0, ARP_TARGET_IP_ADDRESS_OFFSET);
		gen.addJumpIfBytesNotEqual(Register.R0, mIPv4Address, gen.DROP_LABEL);

		// Otherwise, pass
		gen.addJump(gen.PASS_LABEL);
		}

		/**
		* Generate filter code to process IPv4 packets. Execution of this code ends in either the
		* DROP_LABEL or PASS_LABEL and does not fall off the end.
		@@ -563,7 +604,6 @@ public class ApfFilter {
		* DROP_LABEL or PASS_LABEL, or falls off the end for ICMPv6 packets.
		* Preconditions:
		* - Packet being filtered is IPv6
		* - R1 is initialized to 0
		*/
		@GuardedBy("this")
		private void generateIPv6FilterLocked(ApfGenerator gen) throws IllegalInstructionException {
		@@ -595,6 +635,7 @@ public class ApfFilter {
		/**
		* Begin generating an APF program to:
		* <ul>
		* <li>Drop ARP requests not for us, if mIPv4Address is set,
		* <li>Drop IPv4 broadcast packets, except DHCP destined to our MAC,
		* <li>Drop IPv4 multicast packets, if mMulticastFilter,
		* <li>Pass all other IPv4 packets,
		@@ -613,16 +654,31 @@ public class ApfFilter {

		// Here's a basic summary of what the initial program does:
		//
		// if it's ARP:
		// inesrt ARP filter to drop or pass these appropriately
		// if it's IPv4:
		// insert IPv4 filter to drop or pass these appropriately
		// if it's not IPv6:
		// pass
		// insert IPv6 filter to drop, pass, or fall off the end for ICMPv6 packets

		gen.addLoad16(Register.R0, ETH_ETHERTYPE_OFFSET);

		if (mIPv4Address != null) {
		// Add ARP filters:
		String skipArpFiltersLabel = "skipArpFilters";
		// If not ARP, skip ARP filters
		// NOTE: Relies on R0 containing ethertype.
		gen.addJumpIfR0NotEquals(ETH_P_ARP, skipArpFiltersLabel);
		generateArpFilterLocked(gen);
		gen.defineLabel(skipArpFiltersLabel);
		}

		// Add IPv4 filters:
		String skipIPv4FiltersLabel = "skipIPv4Filters";
		// If not IPv4, skip IPv4 filters
		gen.addLoad16(Register.R0, ETH_ETHERTYPE_OFFSET);
		// NOTE: Relies on R0 containing ethertype. This is safe because if we got here, we did not
		// execute the ARP filter, since that filter does not fall through, but either drops or
		// passes.
		gen.addJumpIfR0NotEquals(ETH_P_IP, skipIPv4FiltersLabel);
		// NOTE: Relies on R1 being initialized to 0.
		generateIPv4FilterLocked(gen);
		@@ -631,8 +687,8 @@ public class ApfFilter {
		// Add IPv6 filters:
		// If not IPv6, pass
		// NOTE: Relies on R0 containing ethertype. This is safe because if we got here, we did not
		// execute the IPv4 filter, since that filter does not fall through, but either drops or
		// passes.
		// execute the ARP or IPv4 filters, since those filters do not fall through, but either
		// drop or pass.
		gen.addJumpIfR0NotEquals(ETH_P_IPV6, gen.PASS_LABEL);
		generateIPv6FilterLocked(gen);
		return gen;
		@@ -785,10 +841,36 @@ public class ApfFilter {
		}
		}

		// Find the single IPv4 address if there is one, otherwise return null.
		private static byte[] findIPv4Address(LinkProperties lp) {
		byte[] ipv4Address = null;
		for (InetAddress inetAddr : lp.getAddresses()) {
		byte[] addr = inetAddr.getAddress();
		if (addr.length != 4) continue;
		// More than one IPv4 address, abort
		if (ipv4Address != null && !Arrays.equals(ipv4Address, addr)) return null;
		ipv4Address = addr;
		}
		return ipv4Address;
		}

		public synchronized void setLinkProperties(LinkProperties lp) {
		// NOTE: Do not keep a copy of LinkProperties as it would further duplicate state.
		byte[] ipv4Address = findIPv4Address(lp);
		// If ipv4Address is the same as mIPv4Address, then there's no change, just return.
		if (Arrays.equals(ipv4Address, mIPv4Address)) return;
		// Otherwise update mIPv4Address and install new program.
		mIPv4Address = ipv4Address;
		installNewProgramLocked();
		}

		public synchronized void dump(IndentingPrintWriter pw) {
		pw.println("APF version: " + mApfCapabilities.apfVersionSupported);
		pw.println("Max program size: " + mApfCapabilities.maximumApfProgramSize);
		pw.println("APF caps: " + mApfCapabilities);
		pw.println("Receive thread: " + (mReceiveThread != null ? "RUNNING" : "STOPPED"));
		pw.println("Multicast filtering: " + mMulticastFilter);
		try {
		pw.println("IPv4 address: " + InetAddress.getByAddress(mIPv4Address));
		} catch (UnknownHostException\|NullPointerException e) {}
		if (mLastTimeInstalledProgram == 0) {
		pw.println("No program installed.");
		return;

services/net/java/android/net/ip/IpManager.java

+1 −0

Original line number	Diff line number	Diff line
		@@ -533,6 +533,7 @@ public class IpManager extends StateMachine {
		}

		private void dispatchCallback(ProvisioningChange delta, LinkProperties newLp) {
		if (mApfFilter != null) mApfFilter.setLinkProperties(newLp);
		switch (delta) {
		case GAINED_PROVISIONING:
		if (VDBG) { Log.d(mTag, "onProvisioningSuccess()"); }