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/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.server;
import static android.Manifest.permission.DUMP;
import static android.net.IpSecManager.INVALID_RESOURCE_ID;
import static android.system.OsConstants.AF_INET;
import static android.system.OsConstants.IPPROTO_UDP;
import static android.system.OsConstants.SOCK_DGRAM;
import static com.android.internal.util.Preconditions.checkNotNull;
import android.content.Context;
import android.net.IIpSecService;
import android.net.INetd;
import android.net.IpSecAlgorithm;
import android.net.IpSecConfig;
import android.net.IpSecManager;
import android.net.IpSecSpiResponse;
import android.net.IpSecTransform;
import android.net.IpSecTransformResponse;
import android.net.IpSecUdpEncapResponse;
import android.net.util.NetdService;
import android.os.Binder;
import android.os.IBinder;
import android.os.ParcelFileDescriptor;
import android.os.RemoteException;
import android.os.ServiceSpecificException;
import android.system.ErrnoException;
import android.system.Os;
import android.system.OsConstants;
import android.util.Log;
import android.util.Slog;
import android.util.SparseArray;
import com.android.internal.annotations.GuardedBy;
import java.io.FileDescriptor;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.UnknownHostException;
import java.util.concurrent.atomic.AtomicInteger;
import libcore.io.IoUtils;
/** @hide */
public class IpSecService extends IIpSecService.Stub {
private static final String TAG = "IpSecService";
private static final boolean DBG = Log.isLoggable(TAG, Log.DEBUG);
private static final String NETD_SERVICE_NAME = "netd";
private static final int[] DIRECTIONS =
new int[] {IpSecTransform.DIRECTION_OUT, IpSecTransform.DIRECTION_IN};
private static final int NETD_FETCH_TIMEOUT = 5000; //ms
private static final int MAX_PORT_BIND_ATTEMPTS = 10;
private static final InetAddress INADDR_ANY;
static {
try {
INADDR_ANY = InetAddress.getByAddress(new byte[] {0, 0, 0, 0});
} catch (UnknownHostException e) {
throw new RuntimeException(e);
}
}
static final int FREE_PORT_MIN = 1024; // ports 1-1023 are reserved
static final int PORT_MAX = 0xFFFF; // ports are an unsigned 16-bit integer
/* Binder context for this service */
private final Context mContext;
/** Should be a never-repeating global ID for resources */
private static AtomicInteger mNextResourceId = new AtomicInteger(0x00FADED0);
@GuardedBy("this")
private final ManagedResourceArray<SpiRecord> mSpiRecords = new ManagedResourceArray<>();
@GuardedBy("this")
private final ManagedResourceArray<TransformRecord> mTransformRecords =
new ManagedResourceArray<>();
@GuardedBy("this")
private final ManagedResourceArray<UdpSocketRecord> mUdpSocketRecords =
new ManagedResourceArray<>();
/**
* The ManagedResource class provides a facility to cleanly and reliably release system
* resources. It relies on two things: an IBinder that allows ManagedResource to automatically
* clean up in the event that the Binder dies and a user-provided resourceId that should
* uniquely identify the managed resource. To use this class, the user should implement the
* releaseResources() method that is responsible for releasing system resources when invoked.
*/
private abstract class ManagedResource implements IBinder.DeathRecipient {
final int pid;
final int uid;
private IBinder mBinder;
protected int mResourceId;
private AtomicInteger mReferenceCount = new AtomicInteger(0);
ManagedResource(int resourceId, IBinder binder) {
super();
mBinder = binder;
mResourceId = resourceId;
pid = Binder.getCallingPid();
uid = Binder.getCallingUid();
try {
mBinder.linkToDeath(this, 0);
} catch (RemoteException e) {
binderDied();
}
}
public void addReference() {
mReferenceCount.incrementAndGet();
}
public void removeReference() {
if (mReferenceCount.decrementAndGet() < 0) {
Log.wtf(TAG, "Programming error: negative reference count");
}
}
public boolean isReferenced() {
return (mReferenceCount.get() > 0);
}
public void checkOwnerOrSystemAndThrow() {
if (uid != Binder.getCallingUid()
&& android.os.Process.SYSTEM_UID != Binder.getCallingUid()) {
throw new SecurityException("Only the owner may access managed resources!");
}
}
/**
* When this record is no longer needed for managing system resources this function should
* clean up all system resources and nullify the record. This function shall perform all
* necessary cleanup of the resources managed by this record.
*
* <p>NOTE: this function verifies ownership before allowing resources to be freed.
*/
public final void release() throws RemoteException {
synchronized (IpSecService.this) {
if (isReferenced()) {
throw new IllegalStateException(
"Cannot release a resource that has active references!");
}
if (mResourceId == INVALID_RESOURCE_ID) {
return;
}
releaseResources();
if (mBinder != null) {
mBinder.unlinkToDeath(this, 0);
}
mBinder = null;
mResourceId = INVALID_RESOURCE_ID;
}
}
/**
* If the Binder object dies, this function is called to free the system resources that are
* being managed by this record and to subsequently release this record for garbage
* collection
*/
public final void binderDied() {
try {
release();
} catch (Exception e) {
Log.e(TAG, "Failed to release resource: " + e);
}
}
/**
* Implement this method to release all system resources that are being protected by this
* record. Once the resources are released, the record should be invalidated and no longer
* used by calling release(). This should NEVER be called directly.
*
* <p>Calls to this are always guarded by IpSecService#this
*/
protected abstract void releaseResources() throws RemoteException;
};
/**
* Minimal wrapper around SparseArray that performs ownership
* validation on element accesses.
*/
private class ManagedResourceArray<T extends ManagedResource> {
SparseArray<T> mArray = new SparseArray<>();
T get(int key) {
T val = mArray.get(key);
// The value should never be null unless the resource doesn't exist
// (since we do not allow null resources to be added).
if (val != null) {
val.checkOwnerOrSystemAndThrow();
}
return val;
}
void put(int key, T obj) {
checkNotNull(obj, "Null resources cannot be added");
mArray.put(key, obj);
}
void remove(int key) {
mArray.remove(key);
}
}
private final class TransformRecord extends ManagedResource {
private final IpSecConfig mConfig;
private final SpiRecord[] mSpis;
private final UdpSocketRecord mSocket;
TransformRecord(
int resourceId,
IBinder binder,
IpSecConfig config,
SpiRecord[] spis,
UdpSocketRecord socket) {
super(resourceId, binder);
mConfig = config;
mSpis = spis;
mSocket = socket;
for (int direction : DIRECTIONS) {
mSpis[direction].addReference();
mSpis[direction].setOwnedByTransform();
}
if (mSocket != null) {
mSocket.addReference();
}
}
public IpSecConfig getConfig() {
return mConfig;
}
public SpiRecord getSpiRecord(int direction) {
return mSpis[direction];
}
/** always guarded by IpSecService#this */
@Override
protected void releaseResources() {
for (int direction : DIRECTIONS) {
int spi = mSpis[direction].getSpi();
try {
getNetdInstance()
.ipSecDeleteSecurityAssociation(
mResourceId,
direction,
(mConfig.getLocalAddress() != null)
? mConfig.getLocalAddress().getHostAddress()
: "",
(mConfig.getRemoteAddress() != null)
? mConfig.getRemoteAddress().getHostAddress()
: "",
spi);
} catch (ServiceSpecificException e) {
// FIXME: get the error code and throw is at an IOException from Errno Exception
} catch (RemoteException e) {
Log.e(TAG, "Failed to delete SA with ID: " + mResourceId);
}
}
for (int direction : DIRECTIONS) {
mSpis[direction].removeReference();
}
if (mSocket != null) {
mSocket.removeReference();
}
}
}
private final class SpiRecord extends ManagedResource {
private final int mDirection;
private final String mLocalAddress;
private final String mRemoteAddress;
private int mSpi;
private boolean mOwnedByTransform = false;
SpiRecord(
int resourceId,
IBinder binder,
int direction,
String localAddress,
String remoteAddress,
int spi) {
super(resourceId, binder);
mDirection = direction;
mLocalAddress = localAddress;
mRemoteAddress = remoteAddress;
mSpi = spi;
}
/** always guarded by IpSecService#this */
@Override
protected void releaseResources() {
if (mOwnedByTransform) {
Log.d(TAG, "Cannot release Spi " + mSpi + ": Currently locked by a Transform");
// Because SPIs are "handed off" to transform, objects, they should never be
// freed from the SpiRecord once used in a transform. (They refer to the same SA,
// thus ownership and responsibility for freeing these resources passes to the
// Transform object). Thus, we should let the user free them without penalty once
// they are applied in a Transform object.
return;
}
try {
getNetdInstance()
.ipSecDeleteSecurityAssociation(
mResourceId, mDirection, mLocalAddress, mRemoteAddress, mSpi);
} catch (ServiceSpecificException e) {
// FIXME: get the error code and throw is at an IOException from Errno Exception
} catch (RemoteException e) {
Log.e(TAG, "Failed to delete SPI reservation with ID: " + mResourceId);
}
mSpi = IpSecManager.INVALID_SECURITY_PARAMETER_INDEX;
}
public int getSpi() {
return mSpi;
}
public void setOwnedByTransform() {
if (mOwnedByTransform) {
// Programming error
throw new IllegalStateException("Cannot own an SPI twice!");
}
mOwnedByTransform = true;
}
}
private final class UdpSocketRecord extends ManagedResource {
private FileDescriptor mSocket;
private final int mPort;
UdpSocketRecord(int resourceId, IBinder binder, FileDescriptor socket, int port) {
super(resourceId, binder);
mSocket = socket;
mPort = port;
}
/** always guarded by IpSecService#this */
@Override
protected void releaseResources() {
Log.d(TAG, "Closing port " + mPort);
IoUtils.closeQuietly(mSocket);
mSocket = null;
}
public int getPort() {
return mPort;
}
public FileDescriptor getSocket() {
return mSocket;
}
}
/**
* Constructs a new IpSecService instance
*
* @param context Binder context for this service
*/
private IpSecService(Context context) {
mContext = context;
}
static IpSecService create(Context context) throws InterruptedException {
final IpSecService service = new IpSecService(context);
service.connectNativeNetdService();
return service;
}
public void systemReady() {
if (isNetdAlive()) {
Slog.d(TAG, "IpSecService is ready");
} else {
Slog.wtf(TAG, "IpSecService not ready: failed to connect to NetD Native Service!");
}
}
private void connectNativeNetdService() {
// Avoid blocking the system server to do this
new Thread() {
@Override
public void run() {
synchronized (IpSecService.this) {
NetdService.get(NETD_FETCH_TIMEOUT);
}
}
}.start();
}
INetd getNetdInstance() throws RemoteException {
final INetd netd = NetdService.getInstance();
if (netd == null) {
throw new RemoteException("Failed to Get Netd Instance");
}
return netd;
}
synchronized boolean isNetdAlive() {
try {
final INetd netd = getNetdInstance();
if (netd == null) {
return false;
}
return netd.isAlive();
} catch (RemoteException re) {
return false;
}
}
@Override
/** Get a new SPI and maintain the reservation in the system server */
public synchronized IpSecSpiResponse reserveSecurityParameterIndex(
int direction, String remoteAddress, int requestedSpi, IBinder binder)
throws RemoteException {
int resourceId = mNextResourceId.getAndIncrement();
int spi = IpSecManager.INVALID_SECURITY_PARAMETER_INDEX;
String localAddress = "";
try {
spi =
getNetdInstance()
.ipSecAllocateSpi(
resourceId,
direction,
localAddress,
remoteAddress,
requestedSpi);
Log.d(TAG, "Allocated SPI " + spi);
mSpiRecords.put(
resourceId,
new SpiRecord(resourceId, binder, direction, localAddress, remoteAddress, spi));
} catch (ServiceSpecificException e) {
// TODO: Add appropriate checks when other ServiceSpecificException types are supported
return new IpSecSpiResponse(
IpSecManager.Status.SPI_UNAVAILABLE, IpSecManager.INVALID_RESOURCE_ID, spi);
} catch (RemoteException e) {
throw e.rethrowFromSystemServer();
}
return new IpSecSpiResponse(IpSecManager.Status.OK, resourceId, spi);
}
/* This method should only be called from Binder threads. Do not call this from
* within the system server as it will crash the system on failure.
*/
private synchronized <T extends ManagedResource> void releaseManagedResource(
ManagedResourceArray<T> resArray, int resourceId, String typeName)
throws RemoteException {
// We want to non-destructively get so that we can check credentials before removing
// this from the records.
T record = resArray.get(resourceId);
if (record == null) {
throw new IllegalArgumentException(
typeName + " " + resourceId + " is not available to be deleted");
}
record.release();
resArray.remove(resourceId);
}
/** Release a previously allocated SPI that has been registered with the system server */
@Override
public void releaseSecurityParameterIndex(int resourceId) throws RemoteException {
releaseManagedResource(mSpiRecords, resourceId, "SecurityParameterIndex");
}
/**
* This function finds and forcibly binds to a random system port, ensuring that the port cannot
* be unbound.
*
* <p>A socket cannot be un-bound from a port if it was bound to that port by number. To select
* a random open port and then bind by number, this function creates a temp socket, binds to a
* random port (specifying 0), gets that port number, and then uses is to bind the user's UDP
* Encapsulation Socket forcibly, so that it cannot be un-bound by the user with the returned
* FileHandle.
*
* <p>The loop in this function handles the inherent race window between un-binding to a port
* and re-binding, during which the system could *technically* hand that port out to someone
* else.
*/
private void bindToRandomPort(FileDescriptor sockFd) throws IOException {
for (int i = MAX_PORT_BIND_ATTEMPTS; i > 0; i--) {
try {
FileDescriptor probeSocket = Os.socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
Os.bind(probeSocket, INADDR_ANY, 0);
int port = ((InetSocketAddress) Os.getsockname(probeSocket)).getPort();
Os.close(probeSocket);
Log.v(TAG, "Binding to port " + port);
Os.bind(sockFd, INADDR_ANY, port);
return;
} catch (ErrnoException e) {
// Someone miraculously claimed the port just after we closed probeSocket.
if (e.errno == OsConstants.EADDRINUSE) {
continue;
}
throw e.rethrowAsIOException();
}
}
throw new IOException("Failed " + MAX_PORT_BIND_ATTEMPTS + " attempts to bind to a port");
}
/**
* Open a socket via the system server and bind it to the specified port (random if port=0).
* This will return a PFD to the user that represent a bound UDP socket. The system server will
* cache the socket and a record of its owner so that it can and must be freed when no longer
* needed.
*/
@Override
public synchronized IpSecUdpEncapResponse openUdpEncapsulationSocket(int port, IBinder binder)
throws RemoteException {
if (port != 0 && (port < FREE_PORT_MIN || port > PORT_MAX)) {
throw new IllegalArgumentException(
"Specified port number must be a valid non-reserved UDP port");
}
int resourceId = mNextResourceId.getAndIncrement();
FileDescriptor sockFd = null;
try {
sockFd = Os.socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (port != 0) {
Log.v(TAG, "Binding to port " + port);
Os.bind(sockFd, INADDR_ANY, port);
} else {
bindToRandomPort(sockFd);
}
// This code is common to both the unspecified and specified port cases
Os.setsockoptInt(
sockFd,
OsConstants.IPPROTO_UDP,
OsConstants.UDP_ENCAP,
OsConstants.UDP_ENCAP_ESPINUDP);
mUdpSocketRecords.put(
resourceId, new UdpSocketRecord(resourceId, binder, sockFd, port));
return new IpSecUdpEncapResponse(IpSecManager.Status.OK, resourceId, port, sockFd);
} catch (IOException | ErrnoException e) {
IoUtils.closeQuietly(sockFd);
}
// If we make it to here, then something has gone wrong and we couldn't open a socket.
// The only reasonable condition that would cause that is resource unavailable.
return new IpSecUdpEncapResponse(IpSecManager.Status.RESOURCE_UNAVAILABLE);
}
/** close a socket that has been been allocated by and registered with the system server */
@Override
public void closeUdpEncapsulationSocket(int resourceId) throws RemoteException {
releaseManagedResource(mUdpSocketRecords, resourceId, "UdpEncapsulationSocket");
}
/**
* Create a transport mode transform, which represent two security associations (one in each
* direction) in the kernel. The transform will be cached by the system server and must be freed
* when no longer needed. It is possible to free one, deleting the SA from underneath sockets
* that are using it, which will result in all of those sockets becoming unable to send or
* receive data.
*/
@Override
public synchronized IpSecTransformResponse createTransportModeTransform(
IpSecConfig c, IBinder binder) throws RemoteException {
int resourceId = mNextResourceId.getAndIncrement();
SpiRecord[] spis = new SpiRecord[DIRECTIONS.length];
// TODO: Basic input validation here since it's coming over the Binder
int encapType, encapLocalPort = 0, encapRemotePort = 0;
UdpSocketRecord socketRecord = null;
encapType = c.getEncapType();
if (encapType != IpSecTransform.ENCAP_NONE) {
socketRecord = mUdpSocketRecords.get(c.getEncapLocalResourceId());
encapLocalPort = socketRecord.getPort();
encapRemotePort = c.getEncapRemotePort();
}
for (int direction : DIRECTIONS) {
IpSecAlgorithm auth = c.getAuthentication(direction);
IpSecAlgorithm crypt = c.getEncryption(direction);
spis[direction] = mSpiRecords.get(c.getSpiResourceId(direction));
int spi = spis[direction].getSpi();
try {
getNetdInstance()
.ipSecAddSecurityAssociation(
resourceId,
c.getMode(),
direction,
(c.getLocalAddress() != null)
? c.getLocalAddress().getHostAddress()
: "",
(c.getRemoteAddress() != null)
? c.getRemoteAddress().getHostAddress()
: "",
(c.getNetwork() != null)
? c.getNetwork().getNetworkHandle()
: 0,
spi,
(auth != null) ? auth.getName() : "",
(auth != null) ? auth.getKey() : null,
(auth != null) ? auth.getTruncationLengthBits() : 0,
(crypt != null) ? crypt.getName() : "",
(crypt != null) ? crypt.getKey() : null,
(crypt != null) ? crypt.getTruncationLengthBits() : 0,
encapType,
encapLocalPort,
encapRemotePort);
} catch (ServiceSpecificException e) {
// FIXME: get the error code and throw is at an IOException from Errno Exception
return new IpSecTransformResponse(IpSecManager.Status.RESOURCE_UNAVAILABLE);
}
}
// Both SAs were created successfully, time to construct a record and lock it away
mTransformRecords.put(
resourceId, new TransformRecord(resourceId, binder, c, spis, socketRecord));
return new IpSecTransformResponse(IpSecManager.Status.OK, resourceId);
}
/**
* Delete a transport mode transform that was previously allocated by + registered with the
* system server. If this is called on an inactive (or non-existent) transform, it will not
* return an error. It's safe to de-allocate transforms that may have already been deleted for
* other reasons.
*/
@Override
public void deleteTransportModeTransform(int resourceId) throws RemoteException {
releaseManagedResource(mTransformRecords, resourceId, "IpSecTransform");
}
/**
* Apply an active transport mode transform to a socket, which will apply the IPsec security
* association as a correspondent policy to the provided socket
*/
@Override
public synchronized void applyTransportModeTransform(
ParcelFileDescriptor socket, int resourceId) throws RemoteException {
// Synchronize liberally here because we are using ManagedResources in this block
TransformRecord info;
// FIXME: this code should be factored out into a security check + getter
info = mTransformRecords.get(resourceId);
if (info == null) {
throw new IllegalArgumentException("Transform " + resourceId + " is not active");
}
// TODO: make this a function.
if (info.pid != getCallingPid() || info.uid != getCallingUid()) {
throw new SecurityException("Only the owner of an IpSec Transform may apply it!");
}
IpSecConfig c = info.getConfig();
try {
for (int direction : DIRECTIONS) {
getNetdInstance()
.ipSecApplyTransportModeTransform(
socket.getFileDescriptor(),
resourceId,
direction,
(c.getLocalAddress() != null)
? c.getLocalAddress().getHostAddress()
: "",
(c.getRemoteAddress() != null)
? c.getRemoteAddress().getHostAddress()
: "",
info.getSpiRecord(direction).getSpi());
}
} catch (ServiceSpecificException e) {
// FIXME: get the error code and throw is at an IOException from Errno Exception
}
}
/**
* Remove a transport mode transform from a socket, applying the default (empty) policy. This
* will ensure that NO IPsec policy is applied to the socket (would be the equivalent of
* applying a policy that performs no IPsec). Today the resourceId parameter is passed but not
* used: reserved for future improved input validation.
*/
@Override
public void removeTransportModeTransform(ParcelFileDescriptor socket, int resourceId)
throws RemoteException {
try {
getNetdInstance().ipSecRemoveTransportModeTransform(socket.getFileDescriptor());
} catch (ServiceSpecificException e) {
// FIXME: get the error code and throw is at an IOException from Errno Exception
}
}
@Override
protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
mContext.enforceCallingOrSelfPermission(DUMP, TAG);
// TODO: Add dump code to print out a log of all the resources being tracked
pw.println("IpSecService Log:");
pw.println("NetdNativeService Connection: " + (isNetdAlive() ? "alive" : "dead"));
pw.println();
}
}