Table of Contents

1. Introduction
1.1 History
2. Usage
3. Configuration

1. Introduction

The LDAP plugin adds support for LDAP and Active Directory authentication to a Grails application that uses Spring Security. It depends on the Spring Security Core plugin.

Once you have configured your Grails application as an LDAP client you can delegate authentication to LDAP and not have to manage users' authentication information in your application. By default roles are inferred from LDAP group membership and you can store additional application-specific roles in your database.

Please refer to the Spring Security LDAP documentation for details of the underlying implementation.

1.1 History

2. Usage

Configuring your LDAP server is beyond the scope of this document. There are many different approaches and this will most likely be done by IT staff. It's assumed here that you already have a running LDAP or Active Directory server.

There isn't much that you need to do in your application to use LDAP. Just install this plugin, and configure any required parameters and whatever optional parameters you want in Config.groovy. These are described in detail in Chapter 3 but typically you only need to set these properties

grails.plugins.springsecurity.ldap.context.managerDn = 'uid=admin,ou=system'
grails.plugins.springsecurity.ldap.context.managerPassword = 'secret'
grails.plugins.springsecurity.ldap.context.server = 'ldap://localhost:10389'
grails.plugins.springsecurity.ldap.authorities.groupSearchBase =
     'ou=groups,dc=yourcompany,dc=com' = 'dc=yourcompany,dc=com'

Often all role information will be stored in LDAP, but if you want to also assign application-specific roles to users in the database, then add this

grails.plugins.springsecurity.ldap.authorities.retrieveDatabaseRoles = true

to do an extra database lookup after the LDAP lookup.

Depending on how passwords are encrypted in LDAP you may also need to configure the encryption algorithm, e.g.

grails.plugins.springsecurity.password.algorithm = 'SHA-256'

Sample Config.groovy settings for Active Directory

Active directory is somewhat different although still relatively painless if you know what you are doing. Use these example configuration options to get started (tested in Windows Server 2008):

Replace the placeholders inside brackets with appropriate values and remove the chars

// LDAP config
grails.plugins.springsecurity.ldap.context.managerDn = '[distinguishedName]'
grails.plugins.springsecurity.ldap.context.managerPassword = '[password]'
grails.plugins.springsecurity.ldap.context.server = 'ldap://[ip]:[port]/'
grails.plugins.springsecurity.ldap.authorities.ignorePartialResultException = true // typically needed for Active Directory = '[the base directory to start the search.  usually something like dc=mycompany,dc=com]'"sAMAccountName={0}" // for Active Directory you need this = true
grails.plugins.springsecurity.ldap.auth.hideUserNotFoundExceptions = false = ['mail', 'displayName'] // extra attributes you want returned; see below for custom classes that access this data
grails.plugins.springsecurity.providerNames = ['ldapAuthProvider', 'anonymousAuthenticationProvider'] // specify this when you want to skip attempting to load from db and only use LDAP

// role-specific LDAP config grails.plugins.springsecurity.ldap.useRememberMe = false grails.plugins.springsecurity.ldap.authorities.retrieveGroupRoles = true grails.plugins.springsecurity.ldap.authorities.groupSearchBase ='[the base directory to start the search. usually something like dc=mycompany,dc=com]' grails.plugins.springsecurity.ldap.authorities.groupSearchFilter = 'member={0}' // Active Directory specific - the example settings will work fine for a plain LDAP server

Custom UserDetailsContextMapper

There are three options for mapping LDAP attributes to UserDetails data (as specified by the grails.plugins.springsecurity.ldap.mapper.userDetailsClass config attribute) and hopefully one of those will be sufficient for your needs. If not, it's easy to implement UserDetailsContextMapper yourself.

Create a class in src/groovy or src/java that implements UserDetailsContextMapper and register it in grails-app/conf/spring/resources.groovy:

import com.mycompany.myapp.MyUserDetailsContextMapper

beans = { ldapUserDetailsMapper(MyUserDetailsContextMapper) { // bean attributes } }

For example, here's a custom UserDetailsContextMapper that extracts three additional fields from LDAP (fullname, email, and title)

package com.mycompany.myapp

import org.springframework.ldap.core.DirContextAdapter import org.springframework.ldap.core.DirContextOperations import import

class MyUserDetailsContextMapper implements UserDetailsContextMapper {

UserDetails mapUserFromContext(DirContextOperations ctx, String username, Collection authorities) {

String fullname = ctx.originalAttrs.attrs['name'].values[0] String email = ctx.originalAttrs.attrs['mail'].values[0].toString().toLowerCase() String username = ctx.originalAttrs.attrs['samaccountname'].values[0].toString().toLowerCase() def title = ctx.originalAttrs.attrs['title']

new MyUserDetails(username, null, true, true, true, true, authorities, fullname, email, title == null ? '' : title.values[0]) { }

void mapUserToContext(UserDetails user, DirContextAdapter ctx) { throw new IllegalStateException("Only retrieving data from AD is currently supported") } }

and a custom UserDetails class to hold the extra fields:

package com.mycompany.myapp

import import

class MyUserDetails extends User {

// extra instance variables final String fullname final String email final String title

MyUserDetails(String username, String password, boolean enabled, boolean accountNonExpired, boolean credentialsNonExpired, boolean accountNonLocked, Collection<GrantedAuthority> authorities, String fullname, String email, String title) {

super(username, password, enabled, accountNonExpired, credentialsNonExpired, accountNonLocked, authorities)

this.fullname = fullname = email this.title = title } }

Here we extend the standard Spring Security User class for convenience, but you could also directly implement the interface or use a different base class.

3. Configuration

Any property overrides must be specified in grails-app/conf/Config.groovy using the grails.plugins.springsecurity suffix, for example = true

There are several configuration options for the LDAP plugin. In practice the defaults are fine and only a few will need to be overridden.

NameDefaultMeaning true then searches the entire subtree as identified by context, if false (the default) then only searches the level identified by the context.''Context name to search in, relative to the base of the configured ContextSource, e.g. 'dc=example,dc=com', 'ou=users,dc=example,dc=com''(uid={0})'The filter expression used in the user search link dereferencing during the search (unlimited)The time to wait before the search fails attributesToReturnnull (all)The attributes to return as part of the search
ldap.authenticator.useBindtrueif true uses a BindAuthenticator to bind as the authenticating user, if false uses a PasswordComparisonAuthenticator to lookup the user login name and compare passwords
ldap.authenticator. attributesToReturnnull (all)names of attribute ids to return; use null to return all and an empty list to return none
ldap.authenticator.dnPatternsnull (none)optional pattern(s) used to create DN search patterns, e.g. ["cn={0},ou=people"]
ldap.authenticator. passwordAttributeName'userPassword'the name of the password attribute to use when useBind = false
ldap.mapper. convertToUpperCasetruewhether to uppercase retrieved role names (will also be prefixed with "ROLE_")
ldap.mapper. passwordAttributeName'userPassword'password attribute name to use when building the UserDetails
ldap.mapper. userDetailsClassnull (create an LdapUserDetailsImpl)use 'person' to create a Person, 'inetOrgPerson' to create an InetOrgPerson, or null to create an LdapUserDetailsImpl
ldap.mapper.roleAttributesnulloptional names of role attributes
ldap.auth. hideUserNotFoundExceptionstrueif true throw a new BadCredentialsException, otherwise throw the original UsernameNotFoundException
ldap.auth.useAuthPasswordtrueIf true use the supplied password as the credentials in the authenticationtoken, otherwise obtain the password from the UserDetails object (it may not be possible to read the password from the directory)
ldap.context.managerDn'cn=admin,dc=example, dc=com'DN to authenticate with
ldap.context. managerPassword'secret'username to authenticate with
ldap.context.server'ldap://localhost:389'address of the LDAP server
ldap.context. contextFactoryClassNamecom.sun.jndi.ldap. LdapCtxFactoryclass name of the InitialContextFactory to use
ldap.context. dirObjectFactoryClassNameDefaultDirObjectFactoryclass name of the DirObjectFactory to use
ldap.context. baseEnvironmentPropertiesnoneextra context properties
ldap.context. cacheEnvironmentPropertiestruewhether environment properties should be cached between requsts
ldap.context. anonymousReadOnlyfalsewhether an anonymous environment should be used for read-only operations
ldap.context.referralnull ('ignore')the method to handle referrals. Can be 'ignore' or 'follow' to enable referrals to be automatically followed
ldap.authorities. retrieveGroupRolestruewhether to infer roles based on group membership
ldap.authorities. retrieveDatabaseRolesfalsewhether to retrieve additional roles from the database using the User/Role many-to-many
ldap.authorities. groupRoleAttribute'cn'The ID of the attribute which contains the role name for a group
ldap.authorities. groupSearchFilter'uniquemember={0}'The pattern to be used for the user search. {0} is the user's DN
ldap.authorities. searchSubtreetrueIf true a subtree scope search will be performed, otherwise a single-level search is used
ldap.authorities. groupSearchBase'ou=groups,dc=example, dc=com'The base DN from which the search for group membership should be performed
ldap.authorities. ignorePartialResultExceptionfalseWhether PartialResultExceptions should be ignored in searches, typically used with Active Directory since AD servers often have a problem with referrals.
ldap.authorities.defaultRolenoneAn optional default role to be assigned to all users

Persistent Logins

To use cookies for persistent logins, configure these properties:

Just like with non-LDAP persistent tokens, you need to run the s2-create-persistent-token script to create a persistent login domain class and enable the feature.

ldap.useRememberMefalseWhether to use persistent logins
ldap.rememberMe.detailsManager.attributesToRetrievenull (all)The attributes to return as part of the search
ldap.rememberMe.detailsManager.groupMemberAttributeName'uniquemember'The attribute which contains members of a group
ldap.rememberMe.detailsManager.groupRoleAttributeName'cn'The attribute which corresponds to the role name of a group
ldap.rememberMe.detailsManager.groupSearchBase'ou=groups,dc=example,dc=com'The DN under which groups are stored
ldap.rememberMe.detailsManager.passwordAttributeName'userPassword'Password attribute name
ldap.rememberMe.usernameMapper.userDnBasenone, must be set, e.g. 'dc=example,dc=com', 'ou=users,dc=example,dc=com'The base name of the DN
ldap.rememberMe.usernameMapper.usernameAttributenone, must be set, e.g. 'cn'the attribute to append for the username component