[AMBARI-18938] NPE when authenticating via a Centrify LDAP proxy

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.0
• Fix Version/s: 2.5.0, 2.4.3
• Component/s: ambari-server
• Labels: ldap
• Assignee: Robert Levas
• Reporter: Robert Levas
• Created: 18/Nov/16 20:38
• Updated: 18/Apr/17 17:35
• Resolved: 18/Apr/17 17:35

Description

When authenticating using LDAP where the LDAP server is a Centrify LDAP proxy, a NullPointerException is being thrown due to unexpected missing LDAP user object attributes.

10 Nov 2016 08:23:38,789 ERROR [ambari-client-thread-25] AmbariLdapBindAuthenticator:95 - Caught exception
java.lang.NullPointerException
	at org.apache.ambari.server.security.authorization.AmbariLdapBindAuthenticator.authenticate(AmbariLdapBindAuthenticator.java:83)
	at org.springframework.security.ldap.authentication.LdapAuthenticationProvider.doAuthentication(LdapAuthenticationProvider.java:178)
	at org.springframework.security.ldap.authentication.AbstractLdapAuthenticationProvider.authenticate(AbstractLdapAuthenticationProvider.java:61)
	at org.apache.ambari.server.security.authorization.AmbariLdapAuthenticationProvider.authenticate(AmbariLdapAuthenticationProvider.java:73)
	at org.springframework.security.authentication.ProviderManager.authenticate(ProviderManager.java:156)
	at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:168)
	at org.apache.ambari.server.security.authentication.AmbariAuthenticationFilter.doFilter(AmbariAuthenticationFilter.java:88)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
	at org.apache.ambari.server.security.authorization.AmbariUserAuthorizationFilter.doFilter(AmbariUserAuthorizationFilter.java:91)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
	at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
	at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
	at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
	at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237)
	at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1478)
	at org.apache.ambari.server.api.MethodOverrideFilter.doFilter(MethodOverrideFilter.java:72)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1478)
	at org.apache.ambari.server.api.AmbariPersistFilter.doFilter(AmbariPersistFilter.java:47)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1478)
	at org.apache.ambari.server.security.AbstractSecurityHeaderFilter.doFilter(AbstractSecurityHeaderFilter.java:109)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1478)
	at org.eclipse.jetty.servlets.UserAgentFilter.doFilter(UserAgentFilter.java:82)
	at org.eclipse.jetty.servlets.GzipFilter.doFilter(GzipFilter.java:294)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1478)
	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:499)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137)
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:557)
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:231)
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1086)
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:427)
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193)
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1020)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)
	at org.apache.ambari.server.controller.AmbariHandlerList.processHandlers(AmbariHandlerList.java:212)
	at org.apache.ambari.server.controller.AmbariHandlerList.processHandlers(AmbariHandlerList.java:201)
	at org.apache.ambari.server.controller.AmbariHandlerList.handle(AmbariHandlerList.java:139)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
	at org.eclipse.jetty.server.Server.handle(Server.java:370)
	at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:494)
	at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:973)
	at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:1035)
	at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:641)
	at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:231)
	at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)
	at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:696)
	at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:53)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)
	at java.lang.Thread.run(Thread.java:745)

Cause
The cause for this NPE is related to missing data from the attribute search request made to a Centrify LDAP proxy after a bind has occurred. Since the query filter at this point is "{(objectClass=*}}", the Centrify LDAP proxy does not have enough data to determine what information to return to the caller. However, the filter was something like "{(objectClass=posixAccount}}", it will be able to build a set of attributes to return to the caller since it would determine that the call wants data for a specific profile.

This can be seen by the following tcpdump entry:

LDAPMessage searchRequest(2) "uid=user1,ou=people,ou=dev,dc=apache,dc=org" baseObject
    messageID: 2
    protocolOp: searchRequest (3)
        searchRequest
            baseObject: uid=user1,ou=people,ou=dev,dc=apache,dc=org
            scope: baseObject (0)
            derefAliases: derefAlways (3)
            sizeLimit: 0
            timeLimit: 0
            typesOnly: False
            Filter: (objectClass=*)
            attributes: 0 items
    [Response In: 2]
    controls: 1 item

Note the filter line above: Filter: (objectClass=)*

From the Centrify LDAP proxy logs, the following lines can be seen showing that no mapping is avaialbe:

Nov  8 12:13:45 host1 slapd: cdc search start with filterstr: (objectClass=*)
Nov  8 12:13:45 host1 slapd: cdc search: objectType =  ( is mapped to NONE)
Nov  8 12:13:45 host1 slapd: cdc search after translation filter = (objectClass=*)

This search filter is hardcoded in com.sun.jndi.ldap.LdapCtx as seen in http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b14/com/sun/jndi/ldap/LdapCtx.java#1308.

This code is invoked from the Spring LDAP library after attempting to authenticate using the Spring org.springframework.security.ldap.authentication.BindAuthenticator class.

Solution
To solve this, Ambari should avoid using org.springframework.security.ldap.authentication.BindAuthenticator to authenticate users via LDAP so that more control can be had over when and how user attributes are obtained.

Issue Links

• links to: ReviewBoard