org.apache.sshd.server.keyprovider.SimpleGeneratorHostKeyProvider Maven / Gradle / Ivy
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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.sshd.server.keyprovider;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectStreamClass;
import java.io.ObjectStreamConstants;
import java.io.OutputStream;
import java.io.StreamCorruptedException;
import java.nio.file.Path;
import java.security.GeneralSecurityException;
import java.security.KeyPair;
import java.security.spec.InvalidKeySpecException;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import org.apache.sshd.common.NamedResource;
import org.apache.sshd.common.config.keys.writer.openssh.OpenSSHKeyPairResourceWriter;
import org.apache.sshd.common.session.SessionContext;
import org.apache.sshd.common.util.security.SecurityUtils;
/**
* A simple implementation of an {@link AbstractGeneratorHostKeyProvider} that writes and reads host keys using the
* OpenSSH file format. Legacy keys written by earlier implementations used Java serialization. De-serializing is
* restricted to a small number of classes known to exist in serialized {@link KeyPair}s.
*
* @author Apache MINA SSHD Project
*/
public class SimpleGeneratorHostKeyProvider extends AbstractGeneratorHostKeyProvider {
public SimpleGeneratorHostKeyProvider() {
super();
}
public SimpleGeneratorHostKeyProvider(Path path) {
setPath(path);
}
@Override
protected Iterable doReadKeyPairs(SessionContext session, NamedResource resourceKey, InputStream inputStream)
throws IOException, GeneralSecurityException {
try (BufferedInputStream in = new BufferedInputStream(inputStream)) {
if (isJavaSerialization(in, resourceKey)) {
try (ObjectInputStream r = new ValidatingObjectInputStream(in)) {
return Collections.singletonList((KeyPair) r.readObject());
} catch (ClassNotFoundException e) {
throw new InvalidKeySpecException(
"Cannot de-serialize " + resourceKey + ": missing classes: " + e.getMessage(), e);
}
} else {
return SecurityUtils.loadKeyPairIdentities(null, resourceKey, in, null);
}
}
}
private boolean isJavaSerialization(BufferedInputStream in, NamedResource resourceKey) throws IOException {
in.mark(2);
try {
byte[] magicBytes = new byte[2];
int length = in.read(magicBytes);
if (length != 2) {
throw new StreamCorruptedException("File " + resourceKey + " is not a host key");
}
short magic = (short) (((magicBytes[0] & 0xFF) << 8) | (magicBytes[1] & 0xFF));
return magic == ObjectStreamConstants.STREAM_MAGIC;
} finally {
in.reset();
}
}
@Override
protected void doWriteKeyPair(NamedResource resourceKey, KeyPair kp, OutputStream outputStream)
throws IOException, GeneralSecurityException {
OpenSSHKeyPairResourceWriter writer = new OpenSSHKeyPairResourceWriter();
try (OutputStream out = outputStream) {
writer.writePrivateKey(kp, "host key", null, out);
}
}
private static class ValidatingObjectInputStream extends ObjectInputStream {
private static final Set ALLOWED = new HashSet<>();
static {
ALLOWED.add("[B"); // byte[], used in BC EC key serialization
ALLOWED.add("java.lang.Enum");
ALLOWED.add("java.lang.Number");
ALLOWED.add("java.lang.String");
ALLOWED.add("java.math.BigInteger"); // Used in BC DSA/RSA
ALLOWED.add("java.security.KeyPair");
ALLOWED.add("java.security.PublicKey");
ALLOWED.add("java.security.PrivateKey");
ALLOWED.add("java.security.KeyRep");
ALLOWED.add("java.security.KeyRep$Type");
ALLOWED.add("org.bouncycastle.jcajce.provider.asymmetric.dsa.BCDSAPrivateKey");
ALLOWED.add("org.bouncycastle.jcajce.provider.asymmetric.dsa.BCDSAPublicKey");
ALLOWED.add("org.bouncycastle.jcajce.provider.asymmetric.rsa.BCRSAPrivateCrtKey");
ALLOWED.add("org.bouncycastle.jcajce.provider.asymmetric.rsa.BCRSAPrivateKey");
ALLOWED.add("org.bouncycastle.jcajce.provider.asymmetric.rsa.BCRSAPublicKey");
ALLOWED.add("org.bouncycastle.jcajce.provider.asymmetric.ec.BCECPrivateKey");
ALLOWED.add("org.bouncycastle.jcajce.provider.asymmetric.ec.BCECPublicKey");
ALLOWED.add("com.android.org.bouncycastle.jcajce.provider.asymmetric.dsa.BCDSAPrivateKey");
ALLOWED.add("com.android.org.bouncycastle.jcajce.provider.asymmetric.dsa.BCDSAPublicKey");
ALLOWED.add("com.android.org.bouncycastle.jcajce.provider.asymmetric.rsa.BCRSAPrivateCrtKey");
ALLOWED.add("com.android.org.bouncycastle.jcajce.provider.asymmetric.rsa.BCRSAPrivateKey");
ALLOWED.add("com.android.org.bouncycastle.jcajce.provider.asymmetric.rsa.BCRSAPublicKey");
ALLOWED.add("com.android.org.bouncycastle.jcajce.provider.asymmetric.ec.BCECPrivateKey");
ALLOWED.add("com.android.org.bouncycastle.jcajce.provider.asymmetric.ec.BCECPublicKey");
// net.i2p EdDSA keys cannot be serialized anyway; so no need to whitelist any of their classes.
// They use the default serialization, which writes a great many different classes, but at least
// one of them does not implement Serializable, and thus writing runs into a NotSerializableException.
}
ValidatingObjectInputStream(InputStream in) throws IOException {
super(in);
}
@Override
protected Class resolveClass(ObjectStreamClass desc) throws IOException, ClassNotFoundException {
validate(desc.getName());
return super.resolveClass(desc);
}
private void validate(String className) throws IOException {
if (!ALLOWED.contains(className)) {
throw new IOException(className + " blocked for deserialization");
}
}
}
}