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new cb2cc8e78 [SSHD-1272] Client-side pubkey auth: use session's signature
factories
cb2cc8e78 is described below
commit cb2cc8e78c5b94e58fe88dbd3867e40c618f86db
Author: Thomas Wolf <tw...@apache.org>
AuthorDate: Thu Jun 23 18:34:58 2022 +0200
[SSHD-1272] Client-side pubkey auth: use session's signature factories
When determining the signature algorithm for a public key, fall back
properly to the session's signature factories if none can be found
earlier. Skip keys for which no signature algorithm can be determined.
Provide a way for client code to supply a last-resort default signature
name, if desired.
---
.../pubkey/PublicKeyAuthenticationReporter.java | 12 ++
.../sshd/client/auth/pubkey/UserAuthPublicKey.java | 167 ++++++++++++++-------
2 files changed, 127 insertions(+), 52 deletions(-)
diff --git
a/sshd-core/src/main/java/org/apache/sshd/client/auth/pubkey/PublicKeyAuthenticationReporter.java
b/sshd-core/src/main/java/org/apache/sshd/client/auth/pubkey/PublicKeyAuthenticationReporter.java
index 77197213e..da4eaa054 100644
---
a/sshd-core/src/main/java/org/apache/sshd/client/auth/pubkey/PublicKeyAuthenticationReporter.java
+++
b/sshd-core/src/main/java/org/apache/sshd/client/auth/pubkey/PublicKeyAuthenticationReporter.java
@@ -61,6 +61,18 @@ public interface PublicKeyAuthenticationReporter {
// ignored
}
+ /**
+ * A {@link KeyPair} is is present, but is not attempted because no
signature factory for it could be found.
+ *
+ * @param session The {@link ClientSession}
+ * @param service The requesting service name
+ * @param identity The {@link KeyPair} identity being skipped -
<B>Note:</B> for agent based authentications the
+ * private key may be {@code null}
+ */
+ default void signalIdentitySkipped(ClientSession session, String service,
KeyPair identity) throws Exception {
+ // ignored
+ }
+
/**
* Sending the signed response to the server's challenge
*
diff --git
a/sshd-core/src/main/java/org/apache/sshd/client/auth/pubkey/UserAuthPublicKey.java
b/sshd-core/src/main/java/org/apache/sshd/client/auth/pubkey/UserAuthPublicKey.java
index 274a16f77..52cbc0e0b 100644
---
a/sshd-core/src/main/java/org/apache/sshd/client/auth/pubkey/UserAuthPublicKey.java
+++
b/sshd-core/src/main/java/org/apache/sshd/client/auth/pubkey/UserAuthPublicKey.java
@@ -147,66 +147,83 @@ public class UserAuthPublicKey extends AbstractUserAuth
implements SignatureFact
}
}
PublicKeyAuthenticationReporter reporter =
session.getPublicKeyAuthenticationReporter();
- if (currentAlgorithm == null) {
+ KeyPair keyPair;
+ PublicKey pubKey;
+ do {
+ if (currentAlgorithm == null) {
+ try {
+ current = resolveAttemptedPublicKeyIdentity(session,
service, reporter);
+ } catch (Error e) {
+ warn("sendAuthDataRequest({})[{}] failed ({}) to get next
key: {}", session, service,
+ e.getClass().getSimpleName(), e.getMessage(), e);
+ throw new RuntimeSshException(e);
+ }
+ currentAlgorithms.clear();
+ chosenAlgorithm = null;
+ if (current == null) {
+ if (debugEnabled) {
+ log.debug("resolveAttemptedPublicKeyIdentity({})[{}]
no more keys to send", session, service);
+ }
+
+ if (reporter != null) {
+ reporter.signalAuthenticationExhausted(session,
service);
+ }
+
+ return false;
+ }
+ }
+ if (log.isTraceEnabled()) {
+ log.trace("sendAuthDataRequest({})[{}] current key details:
{}", session, service, current);
+ }
+
try {
- current = resolveAttemptedPublicKeyIdentity(session, service);
+ keyPair = current.getKeyIdentity();
} catch (Error e) {
- warn("sendAuthDataRequest({})[{}] failed ({}) to get next key:
{}",
+ warn("sendAuthDataRequest({})[{}] failed ({}) to retrieve key
identity: {}",
session, service, e.getClass().getSimpleName(),
e.getMessage(), e);
throw new RuntimeSshException(e);
}
- currentAlgorithms.clear();
- chosenAlgorithm = null;
- if (current == null) {
- if (debugEnabled) {
- log.debug("resolveAttemptedPublicKeyIdentity({})[{}] no
more keys to send", session, service);
+ pubKey = keyPair.getPublic();
+
+ if (currentAlgorithm == null) {
+ String keyType = KeyUtils.getKeyType(pubKey);
+ Set<String> aliases = new
TreeSet<>(String.CASE_INSENSITIVE_ORDER);
+ aliases.addAll(KeyUtils.getAllEquivalentKeyTypes(keyType));
+ aliases.add(keyType);
+ List<NamedFactory<Signature>> existingFactories = null;
+ if (current instanceof SignatureFactoriesHolder) {
+ existingFactories = ((SignatureFactoriesHolder)
current).getSignatureFactories();
}
-
- if (reporter != null) {
- reporter.signalAuthenticationExhausted(session, service);
+ if (GenericUtils.isEmpty(existingFactories)) {
+ existingFactories = getSignatureFactories();
}
-
- return false;
- }
- }
- if (log.isTraceEnabled()) {
- log.trace("sendAuthDataRequest({})[{}] current key details: {}",
session, service, current);
- }
-
- KeyPair keyPair;
- try {
- keyPair = current.getKeyIdentity();
- } catch (Error e) {
- warn("sendAuthDataRequest({})[{}] failed ({}) to retrieve key
identity: {}",
- session, service, e.getClass().getSimpleName(),
e.getMessage(), e);
- throw new RuntimeSshException(e);
- }
- PublicKey pubKey = keyPair.getPublic();
-
- if (currentAlgorithm == null) {
- String keyType = KeyUtils.getKeyType(pubKey);
- Set<String> aliases = new TreeSet<>(String.CASE_INSENSITIVE_ORDER);
- aliases.addAll(KeyUtils.getAllEquivalentKeyTypes(keyType));
- aliases.add(keyType);
- List<NamedFactory<Signature>> existingFactories;
- if (current instanceof SignatureFactoriesHolder) {
- existingFactories = ((SignatureFactoriesHolder) current)
- .getSignatureFactories();
- } else {
- existingFactories = getSignatureFactories();
- }
- if (existingFactories != null) {
- // Select the factories by name and in order
- existingFactories.forEach(f -> {
- if (aliases.contains(f.getName())) {
- currentAlgorithms.add(f.getName());
+ if (GenericUtils.isEmpty(existingFactories)) {
+ existingFactories = session.getSignatureFactories();
+ }
+ if (existingFactories != null) {
+ // Select the factories by name and in order
+ existingFactories.forEach(f -> {
+ if (aliases.contains(f.getName())) {
+ currentAlgorithms.add(f.getName());
+ }
+ });
+ }
+ currentAlgorithm = currentAlgorithms.poll();
+ if (GenericUtils.isEmpty(currentAlgorithm)) {
+ currentAlgorithm = getDefaultSignatureAlgorithm(session,
service, current, keyPair, keyType);
+ if (GenericUtils.isEmpty(currentAlgorithm)) {
+ currentAlgorithm = null;
+ if (debugEnabled) {
+ log.debug("sendAuthDataRequest({})[{}] skipping {}
key {}; no signature algorithm", session,
+ service, keyType,
KeyUtils.getFingerPrint(pubKey));
+ }
+ if (reporter != null) {
+ reporter.signalIdentitySkipped(session, service,
keyPair);
+ }
}
- });
+ }
}
- currentAlgorithm = currentAlgorithms.isEmpty()
- ? keyType
- : currentAlgorithms.poll();
- }
+ } while (currentAlgorithm == null);
String name = getName();
Integer hostBoundPubKeyVersion =
session.getAttribute(DefaultClientKexExtensionHandler.HOSTBOUND_AUTHENTICATION);
@@ -239,10 +256,18 @@ public class UserAuthPublicKey extends AbstractUserAuth
implements SignatureFact
}
protected PublicKeyIdentity
resolveAttemptedPublicKeyIdentity(ClientSession session, String service) throws
Exception {
+ return resolveAttemptedPublicKeyIdentity(session, service, null);
+ }
+
+ protected PublicKeyIdentity resolveAttemptedPublicKeyIdentity(
+ ClientSession session, String service,
+ PublicKeyAuthenticationReporter reporter)
+ throws Exception {
if (keys != null) {
while (keys.hasNext()) {
PublicKeyIdentity nextKey = keys.next();
- PublicKey pk = nextKey.getKeyIdentity().getPublic();
+ KeyPair identity = nextKey.getKeyIdentity();
+ PublicKey pk = identity.getPublic();
if (pk instanceof OpenSshCertificate) {
OpenSshCertificate cert = (OpenSshCertificate) pk;
if (!OpenSshCertificate.Type.USER.equals(cert.getType())) {
@@ -250,6 +275,9 @@ public class UserAuthPublicKey extends AbstractUserAuth
implements SignatureFact
"resolveAttemptedPublicKeyIdentity({})[{}]:
public key certificate {} {} (id={}) is not a user certificate",
session, service, KeyUtils.getKeyType(cert),
KeyUtils.getFingerPrint(cert),
cert.getId());
+ if (reporter != null) {
+ reporter.signalIdentitySkipped(session, service,
identity);
+ }
continue;
}
if (!OpenSshCertificate.isValidNow(cert)) {
@@ -257,6 +285,9 @@ public class UserAuthPublicKey extends AbstractUserAuth
implements SignatureFact
"resolveAttemptedPublicKeyIdentity({})[{}]:
public key certificate {} {} (id={}) is not valid now",
session, service, KeyUtils.getKeyType(cert),
KeyUtils.getFingerPrint(cert),
cert.getId());
+ if (reporter != null) {
+ reporter.signalIdentitySkipped(session, service,
identity);
+ }
continue;
}
}
@@ -277,6 +308,38 @@ public class UserAuthPublicKey extends AbstractUserAuth
implements SignatureFact
return new KeyPairIdentity(this, session, kp);
}
+ /**
+ * Determines a signature algorithm name to use for the authentication
request if none could be determined from the
+ * installed signature factories. If a non-{@code null} non-empty string
is returned, it is used <em>as is</em> in
+ * the authentication.
+ * <p>
+ * This is mainly intended for use with identities from an SSH agent,
where the SSH agent may be able to sign the
+ * request even if there is no appropriate signature factory present in
Java. Whether it makes sense to allow this
+ * depends on the application logic and how it handles e.g. SSH config
{@code PubkeyAcceptedKeyTypes} (or
+ * {@code PubkeyAcceptedAlgorithms}}.
+ * </p>
+ * <p>
+ * This default implementation always returns {@code null}, skipping the
key.
+ * </p>
+ *
+ * @param session {@link ClientSession} trying to authenticate
+ * @param service SSH service name
+ * @param identity {@link PublicKeyIdentity} considered to be used for
authentication
+ * @param keyPair {@link KeyPair} from {@code identity}
+ * @param keyType the key type of {@code keyPair}
+ * @return {@code null} or an empty string to skip this key and
consider another key, if any, to use for
+ * authentication, or a non-empty signature algorithm
name to use for the authentication attempt
+ * using the given {@code identity}
+ * @throws Exception if an error occurs
+ * @see KeyAgentIdentity
+ */
+ protected String getDefaultSignatureAlgorithm(
+ ClientSession session, String service, PublicKeyIdentity identity,
+ KeyPair keyPair, String keyType)
+ throws Exception {
+ return null;
+ }
+
@Override
protected boolean processAuthDataRequest(ClientSession session, String
service, Buffer buffer) throws Exception {
String name = getName();
