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Fedora Principal Providers allow a Fedora repository to pull in user security and role designations from other sources (e.g. LDAP).

Principal Providers are consulted after are implemented as servlet filters that are added to the Shiro filter chain between the initial container authentication but before finer-grained authentication (such as role resolution) is applied.The repository configuration file (repository.json) contains the class name of an authentication provider (under "providers") as well as the roles to be used when starting the provider module. By default, the org.fcrepo.auth.common.BypassSecurityServletAuthenticationProvider exists in the configuration file, as it doesn't rely on an external PrincipalProvider and offers the simplest authentication model (the module always gives access privileges to the sessionauthentication filter (ServletContainerAuthFilter) and the final authorization filter (WebACFilter).

Different derivatives of the PrincipalProvider class can be initialized differently, either through the repository.json file, other credential files, from information sent via HTTP header or by connecting to external information sources such as LDAP.

PrincipalProvider

The interface that custom providers must implement. Several providers exist in the codebase.

Configuration

Principal providers are configured in Fedora's Spring configuration by doing the following:

1. Add a <bean> definition for the desired provider, including any necessary configuration parameters. See below for the configuration parameters for the providers that exist in Fedora's core codebase.
2. Add the name of the bean to the filterChainDefinitions line in the configuration of the org.apache.shiro.spring.web.ShiroFilterFactoryBean. The relevant line starts with /**, which means "filter all requests". What follows is a comma-separated list of filter bean names. The request proceeds through the filters from left to right.

Here is the complete default Spring filter configuration used by the fcrepo-webapp:A principal provider must be configured in repo.xml. The following examples shows configuration for a PrincipalProvider class ContainerRolesPrincipalProvider.

<!-- Authentication Filter -->
<bean id="servletContainerAuthFilter<bean name="containerRolesPrincipalProvider" class="org.fcrepo.auth.common.ContainerRolesPrincipalProviderServletContainerAuthFilter"/>

<!-- Principal Provider Filter: Delegate Header -->
<bean    p:roleNames="my-new-tomcat-role"/name="delegatedPrincipalProvider" class="org.fcrepo.auth.common.DelegateHeaderPrincipalProvider"/>

<!-- Authorization Filter -->
<bean nameid="authenticationProviderwebACFilter" class="org.fcrepo.auth.commonwebac.ServletContainerAuthenticationProviderWebACFilter"/>

<!-- connect the filters into a chain -->
<bean id="shiroFilter" class="org.apache.shiro.spring.web.ShiroFilterFactoryBean">
  <property p:fad-refname="fadsecurityManager" p:principalProviders-ref="containerRolesPrincipalProvidersecurityManager"/>
  <property name="filterChainDefinitions">
    <value>
      <!-- The Auth filter should come first, followed by 0 or more of the principal provider filters, -->
      <!-- and finally the webACFilter -->
      /** = servletContainerAuthFilter,delegatedPrincipalProvider,webACFilter
    </value>
  </property>
</bean>

Classes

Container Roles Principal Provider

ContainerRolesPrincipalProvider is a PrincpalProivder that obtains its set of principals from web.xml.

<bean name="containerRolesProvider" class="org.fcrepo.auth.common.ContainerRolesPrincipalProvider">
  <property name="roleNames">
    <util:set set-class="java.util.HashSet">
      <value>tomcat-role-1</value>
      <value>tomcat-role-2</value>
    </util:set>
  </property>
</bean>

New roles must be specified in web.xml as shown below. The default role is fedoraUser.

<auth-constraint>
  <role-name>fedoraUser</role-name>
  <role-name>fedoraAdmin</role-name>
  <role-name>my-new-tomcat-role<-name>tomcat-role-1</role-name>
  <role-name>tomcat-role-2</role-name>
</auth-constraint>

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HttpHeaderPrincipalProvider is a Principal Provider that obtains its initial set of principals from HTTP header requests.

    <!-- Optional PrincipalProvider that will inspect the request header, "some-header", for user role values -->
    <bean name="headerProvider" class="org.fcrepo.auth.common.HttpHeaderPrincipalProvider">
        <property name="headerName" value="some-header"/>
        <property name="separator" value=","/>
    </bean>
	<bean name="authenticationProvider" class="org.fcrepo.auth.common.ServletContainerAuthenticationProvider"
          p:fad-ref="fad" p:principalProviders-ref="headerProvider"/>

Delegate Header Principal Provider

DelegateHeaderPrincipalProvider is a Principal Provider that uses the On-Behalf-Of HTTP header to switch the user principal to the principal given in the header. This switch is only performed if the authenticated user has the fedoraAdmin container role.

<bean name="delegatedPrincipalProvider" class="org.fcrepo.auth.common.DelegateHeaderPrincipalProvider"/>
<bean name="authenticationProvider" class="org.fcrepo.auth.common.ServletContainerAuthenticationProvider"
          p:fad-ref="fad" p:principalProviders-ref="delegatedPrincipalProvider"/>

Implementation Details

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