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Try all public key algorithms available for a specific key type in SSH_MSG_USERAUTH_REQUEST #763

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Merged
hierynomus merged 1 commit into from
Feb 4, 2022
Merged

Try all public key algorithms available for a specific key type in SSH_MSG_USERAUTH_REQUEST #763

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3 changes: 2 additions & 1 deletion src/main/java/net/schmizz/sshj/transport/Transport.java
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@

import java.io.InputStream;
import java.io.OutputStream;
import java.util.List;
import java.util.concurrent.TimeUnit;

/** Transport layer of the SSH protocol. */
Expand Down Expand Up @@ -224,5 +225,5 @@ long write(SSHPacket payload)
void die(Exception e);

KeyAlgorithm getHostKeyAlgorithm();
KeyAlgorithm getClientKeyAlgorithm(KeyType keyType) throws TransportException;
List<KeyAlgorithm> getClientKeyAlgorithms(KeyType keyType) throws TransportException;
}
12 changes: 8 additions & 4 deletions src/main/java/net/schmizz/sshj/transport/TransportImpl.java
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Expand Up @@ -33,6 +33,7 @@
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReentrantLock;
Expand Down Expand Up @@ -637,15 +638,18 @@ public KeyAlgorithm getHostKeyAlgorithm() {
}

@Override
public KeyAlgorithm getClientKeyAlgorithm(KeyType keyType) throws TransportException {
public List<KeyAlgorithm> getClientKeyAlgorithms(KeyType keyType) throws TransportException {
List<Factory.Named<KeyAlgorithm>> factories = getConfig().getKeyAlgorithms();
List<KeyAlgorithm> available = new ArrayList<>();
if (factories != null)
for (Factory.Named<KeyAlgorithm> f : factories)
if (
f instanceof KeyAlgorithms.Factory && ((KeyAlgorithms.Factory) f).getKeyType().equals(keyType)
|| !(f instanceof KeyAlgorithms.Factory) && f.getName().equals(keyType.toString())
|| !(f instanceof KeyAlgorithms.Factory) && f.getName().equals(keyType.toString())
)
return f.create();
throw new TransportException("Cannot find an available KeyAlgorithm for type " + keyType);
available.add(f.create());
if (available.isEmpty())
throw new TransportException("Cannot find an available KeyAlgorithm for type " + keyType);
return available;
}
}
23 changes: 21 additions & 2 deletions src/main/java/net/schmizz/sshj/userauth/method/KeyedAuthMethod.java
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Original file line number Diff line number Diff line change
Expand Up @@ -27,17 +27,36 @@
import java.io.IOException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.util.LinkedList;
import java.util.Queue;

public abstract class KeyedAuthMethod
extends AbstractAuthMethod {

protected final KeyProvider kProv;
private Queue<KeyAlgorithm> available;

public KeyedAuthMethod(String name, KeyProvider kProv) {
super(name);
this.kProv = kProv;
}

private KeyAlgorithm getPublicKeyAlgorithm(KeyType keyType) throws TransportException {
if (available == null) {
available = new LinkedList<>(params.getTransport().getClientKeyAlgorithms(keyType));
}
return available.peek();
}

@Override
public boolean shouldRetry() {
if (available != null) {
available.poll();
return !available.isEmpty();
}
return false;
}

protected SSHPacket putPubKey(SSHPacket reqBuf)
throws UserAuthException {
PublicKey key;
Expand All @@ -50,7 +69,7 @@ protected SSHPacket putPubKey(SSHPacket reqBuf)
// public key as 2 strings: [ key type | key blob ]
KeyType keyType = KeyType.fromKey(key);
try {
KeyAlgorithm ka = params.getTransport().getClientKeyAlgorithm(keyType);
KeyAlgorithm ka = getPublicKeyAlgorithm(keyType);
if (ka != null) {
reqBuf.putString(ka.getKeyAlgorithm())
.putString(new Buffer.PlainBuffer().putPublicKey(key).getCompactData());
Expand All @@ -74,7 +93,7 @@ protected SSHPacket putSig(SSHPacket reqBuf)
final KeyType kt = KeyType.fromKey(key);
Signature signature;
try {
signature = params.getTransport().getClientKeyAlgorithm(kt).newSignature();
signature = getPublicKeyAlgorithm(kt).newSignature();
} catch (TransportException e) {
throw new UserAuthException("No KeyAlgorithm configured for key " + kt);
}
Expand Down