We are having trouble getting LDAPS referrals working with an Elytron LDAP realm. The issue is the following stack trace.

javax.security.sasl.SaslException: ELY05012: Authentication mechanism server-side authentication failed [Caused by org.wildfly.security.auth.server.RealmUnavailableException: ELY01153: Direct LDAP verification failed with DN [redacted] and absolute DN [null]]

        at org.wildfly.security.sasl.plain.PlainSaslServer.evaluateResponse(PlainSaslServer.java:121)

        at org.wildfly.security.sasl.util.AuthenticationCompleteCallbackSaslServerFactory$1.evaluateResponse(AuthenticationCompleteCallbackSaslServerFactory.java:58)

        at org.wildfly.security.sasl.util.AuthenticationTimeoutSaslServerFactory$DelegatingTimeoutSaslServer.evaluateResponse(AuthenticationTimeoutSaslServerFactory.java:106)

        at org.wildfly.security.sasl.util.SecurityIdentitySaslServerFactory$1.evaluateResponse(SecurityIdentitySaslServerFactory.java:59)

        at org.xnio.sasl.SaslUtils.evaluateResponse(SaslUtils.java:245)

        at org.xnio.sasl.SaslUtils.evaluateResponse(SaslUtils.java:217)

        at org.jboss.remoting3.remote.ServerConnectionOpenListener$AuthStepRunnable.run(ServerConnectionOpenListener.java:486)

        at org.jboss.remoting3.EndpointImpl$TrackingExecutor.lambda$execute$0(EndpointImpl.java:926)

        at org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)

        at org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1985)

        at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1487)

        at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1349)

        at java.lang.Thread.run(Thread.java:748)

Caused by: org.wildfly.security.auth.server.RealmUnavailableException: ELY01153: Direct LDAP verification failed with DN [redacted] and absolute DN [null]

        at org.wildfly.security.auth.realm.ldap.DirectEvidenceVerifier$1.verifyEvidence(DirectEvidenceVerifier.java:104)

        at org.wildfly.security.auth.realm.ldap.LdapSecurityRealm$LdapRealmIdentity.verifyEvidence(LdapSecurityRealm.java:609)

        at org.wildfly.security.auth.realm.AggregateSecurityRealm$Identity.verifyEvidence(AggregateSecurityRealm.java:155)

        at org.wildfly.security.auth.server.ServerAuthenticationContext$NameAssignedState.verifyEvidence(ServerAuthenticationContext.java:1977)

        at org.wildfly.security.auth.server.ServerAuthenticationContext.verifyEvidence(ServerAuthenticationContext.java:759)

        at org.wildfly.security.auth.server.ServerAuthenticationContext$1.handleOne(ServerAuthenticationContext.java:992)

        at org.wildfly.security.auth.server.ServerAuthenticationContext$1.handleOne(ServerAuthenticationContext.java:902)

        at org.wildfly.security.auth.server.ServerAuthenticationContext$1.handle(ServerAuthenticationContext.java:839)

        at org.wildfly.security.sasl.util.SSLQueryCallbackHandler.handle(SSLQueryCallbackHandler.java:60)

        at org.wildfly.security.sasl.util.TrustManagerSaslServerFactory.lambda$createSaslServer$0(TrustManagerSaslServerFactory.java:96)

        at org.wildfly.security.sasl.plain.PlainSaslServer.evaluateResponse(PlainSaslServer.java:117)

        ... 12 more

Caused by: javax.naming.CommunicationException: ldap.acme.com:636 [Root exception is java.lang.ClassNotFoundException: org.wildfly.security.auth.realm.ldap.ThreadLocalSSLSocketFactory from [Module "org.wildfly.extension.io" version 5.0.0.Final from local module loader @7586beff (finder: local module finder @3b69e7d1 (roots: redacted))]]

        at com.sun.jndi.ldap.Connection.<init>(Connection.java:226)

        at com.sun.jndi.ldap.LdapClient.<init>(LdapClient.java:137)

        at com.sun.jndi.ldap.LdapClient.getInstance(LdapClient.java:1615)

        at com.sun.jndi.ldap.LdapCtx.connect(LdapCtx.java:2749)

        at com.sun.jndi.ldap.LdapCtx.ensureOpen(LdapCtx.java:2699)

        at com.sun.jndi.ldap.LdapCtx.ensureOpen(LdapCtx.java:2673)

        at com.sun.jndi.ldap.LdapCtx.reconnect(LdapCtx.java:2669)

        at org.wildfly.security.auth.realm.ldap.DelegatingLdapContext.reconnect(DelegatingLdapContext.java:181)

        at org.wildfly.security.auth.realm.ldap.DirectEvidenceVerifier$1.verifyEvidence(DirectEvidenceVerifier.java:97)

        ... 22 more

Caused by: java.lang.ClassNotFoundException: org.wildfly.security.auth.realm.ldap.ThreadLocalSSLSocketFactory from [Module "org.wildfly.extension.io" version 5.0.0.Final from local module loader @7586beff (finder: local module finder @3b69e7d1 (roots: redacted))]

        at org.jboss.modules.ModuleClassLoader.findClass(ModuleClassLoader.java:255)

        at org.jboss.modules.ConcurrentClassLoader.performLoadClassUnchecked(ConcurrentClassLoader.java:410)

        at org.jboss.modules.ConcurrentClassLoader.performLoadClass(ConcurrentClassLoader.java:398)

        at org.jboss.modules.ConcurrentClassLoader.loadClass(ConcurrentClassLoader.java:116)

        at java.lang.Class.forName0(Native Method)

        at java.lang.Class.forName(Class.java:348)

        at com.sun.jndi.ldap.VersionHelper12.loadClass(VersionHelper12.java:72)

        at com.sun.jndi.ldap.Connection.createSocket(Connection.java:281)

        at com.sun.jndi.ldap.Connection.<init>(Connection.java:203)

        ... 30 more

As you can see the Sun/Oracle LDAP classes try to load the class "org.wildfly.security.auth.realm.ldap.ThreadLocalSSLSocketFactor" using the TCCL which is the "org.wildfly.extension.io" module loader. This will not work as ThreadLocalSSLSocketFactor is in the module "org.wildfy.security.elytron-private".

We have a custom patch against DelegatingLdapContext where we call

Thread.currentThread().setContextClassLoader(ThreadLocalSSLSocketFactory.class.getClassLoader());

before calling

ThreadLocalSSLSocketFactory.set

This gets LDAPS referrals working but is a bit hack-ish.