Spring Security pre-authentication - gives me a new session even though principal is unchanged - session

Question

I have implemented a spring security preathentication filter in my Grails application in order to integrate with Tivoli Access Manager.
The filter getting called for every request in my web application - yet even though the filter returns the same principal as a previous request, it seems to create a new session. I have created a ApplicationListener to listen for authentication events and I can see a new AuthenticationSuccessEvent, with a new session id for each request.
This means all my session variables get cleared each request- which wouldn't be a big deal but it breaks the uploadr plugin.
When I turn debug logging on for my preauthentication filter I see that it thinks the principal has changed, even though it has not:
2015-03-04 11:34:57.769 foobar.TamAuthenticationFilter Checking secure context token: org.springframework.security.web.authentication.preauth.PreAuthenticatedAuthenticationToken#f0666480: Principal: grails.plugin.springsecurity.userdetails.GrailsUser#3125618: Username: 66734; Password: [PROTECTED]; Enabled: true; AccountNonExpired: true; credentialsNonExpired: true; AccountNonLocked: true; Granted Authorities: ROLE_ADMIN,ROLE_APPROVER; Credentials: [PROTECTED]; Authenticated: true; Details: org.springframework.security.web.authentication.WebAuthenticationDetails#fffde5d4: RemoteIpAddress: 0:0:0:0:0:0:0:1; SessionId: 87928D9E25D98DD3CCFAC5D67689E609; Granted Authorities: ROLE_ADMIN, ROLE_APPROVER
2015-03-04 11:34:57.770 foobar.TamAuthenticationFilter Pre-authenticated principal has changed to 66734 and will be reauthenticated
2015-03-04 11:34:57.770 foobar.TamAuthenticationFilter Invalidating existing session
2015-03-04 11:34:57.771 foobar.TamAuthenticationFilter preAuthenticatedPrincipal = 66734, trying to authenticate
How can I make spring security use the same session for each principal returned by the pre authentication filter, rather than create a new one for every request?
here is my filter:
package foobar
import org.springframework.security.web.authentication.preauth.AbstractPreAuthenticatedProcessingFilter
import grails.util.Environment
import grails.util.Holders
import groovy.util.logging.Log4j
#Log4j
class TamAuthenticationFilter extends AbstractPreAuthenticatedProcessingFilter {
java.lang.Object getPreAuthenticatedCredentials(javax.servlet.http.HttpServletRequest request)
{
"N/A"
}
java.lang.Object getPreAuthenticatedPrincipal(javax.servlet.http.HttpServletRequest request)
{
Long staffId = getStaffIdFromTamHeader(request)
if(!staffId)
log.error "iv-user header not found"
return staffId
}
/**
* Get Staff ID from the ivUser Tamheader.
* #param request
* #return
*/
static public Long getStaffIdFromTamHeader(request) {
return request.getHeader("iv-user")
}
}
LoggingSecurityEventListener:
package foobar
import groovy.util.logging.Log4j
import org.springframework.context.ApplicationListener
import org.springframework.security.authentication.event.AbstractAuthenticationEvent
#Log4j
class LoggingSecurityEventListener implements
ApplicationListener<AbstractAuthenticationEvent> {
void onApplicationEvent(AbstractAuthenticationEvent event) {
def username = event.authentication.principal
def address = event.authentication.details.remoteAddress
def sessionId = event.authentication.details.sessionId
log.info "event=${event.class.simpleName} username=${username} remoteAddress=${address} sessionId=${sessionId}"
}
}
resources.groovy:
beans = {
//
// grabs the user id from the tam headers
//
tamAuthenticationFilter(TamAuthenticationFilter) {
authenticationManager = ref('authenticationManager')
checkForPrincipalChanges = true
}
tamAuthenticationProvider(PreAuthenticatedAuthenticationProvider) {
preAuthenticatedUserDetailsService = ref('authenticationUserDetailsService')
}
//
// we do not want to redirect to the auth/login page since we are using tam
//
authenticationEntryPoint(Http403ForbiddenEntryPoint)
securityEventListener(LoggingSecurityEventListener)
}
config.groovy:
grails.plugin.springsecurity.useSecurityEventListener = true
grails.plugin.springsecurity.providerNames = ['tamAuthenticationProvider']
grails.plugin.springsecurity.userLookup.userDomainClassName = 'strobe.auth.User'
grails.plugin.springsecurity.userLookup.authorityJoinClassName = 'strobe.auth.UserRole'
grails.plugin.springsecurity.authority.className = 'strobe.auth.Role'
grails.plugin.springsecurity.securityConfigType="InterceptUrlMap"
grails.plugin.springsecurity.interceptUrlMap = [
'/foobar/**': ['ROLE_USER']]
bootstrap.groovy:
def init = { servletContext -> SpringSecurityUtils.clientRegisterFilter('tamAuthenticationFilter',
SecurityFilterPosition.PRE_AUTH_FILTER.order + 10)
}

Answer 1

I have found the solution to my problem- I was returning a Long from getPreauthenticatedPrincipal() which confuses spring security, as the method requiresAuthentication() in AbstractPreauthenticatedProcessingFilter has this line of code:
if ((principal instanceof String) && currentUser.getName().equals(principal)) {
return false;
}
It expects the principal to be a String. Every time I returned a long it would reauthenticate and give me a new session.
I can't believe the solution was that simple and it took me 2 days to figure out!!!
Part of the problem I think is the scant documentation on preauthentication in spring and also the method signature of:
java.lang.Object getPreAuthenticatedPrincipal(javax.servlet.http.HttpServletRequest request)
which doesn't clearly suggest a return type.