FunctionAuthnConfiguration

Current File(s): conf/authn/authn.properties
Format: Native Spring, Properties

1 Overview
2 General Configuration
- 2.1 Use of Cookies
3 Reference
4 Notes

Overview

The authn/Function login flow is an extension point that allows authentication to be handled by a deployer-supplied Function object, which can be written in Java, a scripting language, etc. It simplifies authoring certain kinds of custom login flows (essentially it provides the "flow" part) and potentially simplifies some MultiFactorAuthnConfiguration scenarios by moving some of the logic into a separate component.

General Configuration

Dome generic settings applicable to all login flows are in authn/authn.properties.

Note for Upgraded Systems

The old file conf/authn/function-authn-config.xml is now supported only for compatibility and generally not installed or needed going forward.

The core of the flow’s configuration is a required bean named shibboleth.authn.Function.ResultLookupStrategy, of type Function<ProfileRequestContext,Object>, which you may define in global.xml.

If the Function returns a null, then authentication fails (this is how to signal a controlled failure). Otherwise, the Function can return a String (the username), a Principal, or a Subject, and the system will construct an appropriate AuthenticationResult around whatever is returned. You may also raise an exception if desired.

A simple scripted example that is more or less an emulation of the RemoteUser flow:

    <bean id="shibboleth.authn.Function.ResultLookupStrategy"
            parent="shibboleth.ContextFunctions.Scripted" factory-method="inlineScript"
            customObject-ref="shibboleth.HttpServletRequestSupplier">
        <constructor-arg>
            <value>
            <![CDATA[
                custom.get().getRemoteUser();
            ]]>
            </value>
        </constructor-arg>
    </bean>

Use of Cookies

Since a common use case is to be able to read and write cookies, note that there's already a component that handles this called a CookieManager. There are built-in objects of this type that will reuse standard properties controlling cookie domain, path, flags, etc. and that's usually the best way to do things. Simply inject an instance of shibboleth.CookieManager or shibboleth.PersistentCookieManager into a Java-based Function implementation, or as a customObject-ref property of a bean inheriting from shibboleth.ContextFunctions.Scripted or shibboleth.ContextFunctions.Expression, to use it to read and write cookies for you.

Reference

Beans that may be defined in global.xml:

Bean ID / Type	Default	Function

Bean ID / Type

Default

Function

shibboleth.authn.Function.resultLookupStrategy

Function<ProfileRequestContext,Object>

A function to produce the authentication result (see above)

shibboleth.authn.Function.resultCachingPredicate

Predicate<ProfileRequestContext>

An optional bean that can be defined to control whether to preserve the authentication result in an IdP session

shibboleth.authn.Function.ClassifiedMessageMap

Map<String,Collection<String>>

Remaps NoCredentials and InvalidCredentials into ReselectFlow for fall-through behavior

Optional remapping of exception messages or events into specific Spring Web Flow events.

The general properties configuring this flow via authn/authn.properties are:

Name	Default	Description

Name	Default	Description
idp.authn.Function.order	1000	Flow priority relative to other enabled login flows (lower is "higher" in priority)
idp.authn.Function.nonBrowserSupported	true	Whether the flow should handle non-browser request profiles (e.g., ECP)
idp.authn.Function.passiveAuthenticationSupported	true	Whether the flow allows for passive authentication
idp.authn.Function.forcedAuthenticationSupported	false	Whether the flow supports forced authentication
idp.authn.Function.proxyRestrictionsEnforced	%{idp.authn.enforceProxyRestrictions:true}	Whether the flow enforces upstream IdP-imposed restrictions on proxying
idp.authn.Function.proxyScopingEnforced	false	Whether the flow considers itself to be proxying, and therefore enforces SP-signaled restrictions on proxying
idp.authn.Function.discoveryRequired	false	Whether to invoke IdP-discovery prior to running flow
idp.authn.Function.lifetime	%{idp.authn.defaultLifetime:PT1H}	Lifetime of results produced by this flow
idp.authn.Function.inactivityTimeout	%{idp.authn.defaultTimeout:PT30M}	Inactivity timeout of results produced by this flow
idp.authn.Function.reuseCondition	shibboleth.Conditions.TRUE	Bean ID of Predicate<ProfileRequestContext> controlling result reuse for SSO
idp.authn.Function.activationCondition	shibboleth.Conditions.TRUE	Bean ID of Predicate<ProfileRequestContext> determining whether flow is usable for request
idp.authn.Function.subjectDecorator		Bean ID of BiConsumer<ProfileRequestContext,Subject> for subject customization
idp.authn.Function.supportedPrincipals	(see below)	Comma-delimited list of protocol-specific Principal strings associated with flow
idp.authn.Function.addDefaultPrincipals	true	Whether to auto-attach the preceding set of Principal objects to each Subject produced by this flow

Most of the flows, including this one, default to describing themselves in terms of "password"-based authentication, so the supportedPrincipals property defaults to the following XML:

<list>
    <bean parent="shibboleth.SAML2AuthnContextClassRef"
        c:classRef="urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport" />
    <bean parent="shibboleth.SAML2AuthnContextClassRef"
        c:classRef="urn:oasis:names:tc:SAML:2.0:ac:classes:Password" />
    <bean parent="shibboleth.SAML1AuthenticationMethod"
        c:method="urn:oasis:names:tc:SAML:1.0:am:password" />
</list>

In property form, this is expressed as (note especially the trailing commas, which MUST be there):

idp.authn.Function.supportedPrincipals = \
    saml2/urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport, \
    saml2/urn:oasis:names:tc:SAML:2.0:ac:classes:Password, \
    saml1/urn:oasis:names:tc:SAML:1.0:am:password

To replace the internally defined flow descriptor bean, the following XML is required:

In older versions and upgraded systems, this list is defined in conf/authn/general-authn.xml. In V5, no default version of the list is provided and it may simply be placed in conf/global.xml if needed.

Notes

Note that upgraded systems will have alternate, legacy approaches to configuring this feature, as noted above.