# The Security Namespace

This appendix provides a reference to the elements available in the security namespace and information on the underlying beans they create (a knowledge of the individual classes and how they work together is assumed - you can find more information in the project Javadoc and elsewhere in this document). If you haven't used the namespace before, please read the introductory chapter on namespace configuration, as this is intended as a supplement to the information there. Using a good quality XML editor while editing a configuration based on the schema is recommended as this will provide contextual information on which elements and attributes are available as well as comments explaining their purpose. The namespace is written in RELAX NG Compact format and later converted into an XSD schema. If you are familiar with this format, you may wish to examine the schema file directly.

## Web Application Security - the `<http>` Element

If you use an `<http>` element within your application, a `FilterChainProxy` bean named "springSecurityFilterChain" is created and the configuration within the element is used to build a filter chain within `FilterChainProxy`. As of Spring Security 3.1, additional `http` elements can be used to add extra filter chains See the introductory chapter for how to set up the mapping from your `web.xml` . Some core filters are always created in a filter chain and others will be added to the stack depending on the attributes and child elements which are present. The positions of the standard filters are fixed (see the filter order table in the namespace introduction), removing a common source of errors with previous versions of the framework when users had to configure the filter chain explicitly in the`FilterChainProxy` bean. You can, of course, still do this if you need full control of the configuration.

All filters which require a reference to the AuthenticationManager will be automatically injected with the internal instance created by the namespace configuration (see the introductory chapter for more on the AuthenticationManager).

Each `<http>` namespace block always creates an `SecurityContextPersistenceFilter`, an `ExceptionTranslationFilter` and a `FilterSecurityInterceptor`. These are fixed and cannot be replaced with alternatives.

### `<http>` Attributes

The attributes on the `<http>` element control some of the properties on the core filters.

#### `pattern`

Defining a pattern for the `http` element controls the requests which will be filtered through the list of filters which it defines. The interpretation is dependent on the configured request-matcher. If no pattern is defined, all requests will be matched, so the most specific patterns should be declared first.

#### `security`

A request pattern can be mapped to an empty filter chain, by setting this attribute to `none`. No security will be applied and none of Spring Security's features will be available.

#### `servlet-api-provision`

Provides versions of `HttpServletRequest` security methods such as `isUserInRole()` and `getPrincipal()` which are implemented by adding a `SecurityContextHolderAwareRequestFilter` bean to the stack. Defaults to "true".

#### `request-matcher`

Defines the RequestMatcher strategy used in the `FilterChainProxy` and the beans created by the `intercept-url` to match incoming requests. Options are currently `ant`, `regex` and `ciRegex`, for ant, regular-expression and case-insensitive regular-expression repsectively. A separate instance is created for each `intercept-url` element using its `pattern` and `method` attributes (see below). Ant paths are matched using an `AntPathRequestMatcher` and regular expressions are matched using a `RegexRequestMatcher`. See the Javadoc for these classes for more details on exactly how the matching is preformed. Ant paths are the default strategy.

#### `realm`

Sets the realm name used for basic authentication (if enabled). Corresponds to the `realmName` property on `BasicAuthenticationEntryPoint`.

#### `entry-point-ref`

Normally the AuthenticationEntryPoint used will be set depending on which authentication mechanisms have been configured. This attribute allows this behaviour to be overridden by defining a customized AuthenticationEntryPoint bean which will start the authentication process.

#### `security-context-repository-ref`

Allows injection of a custom SecurityContextRepository into the `SecurityContextPersistenceFilter`.

#### `access-decision-manager-ref`

Optional attribute specifying the ID of the AccessDecisionManager implementation which should be used for authorizing HTTP requests. By default an `AffirmativeBased` implementation is used for with a `RoleVoter` and an `AuthenticatedVoter`.

#### `access-denied-page`

Deprecated in favour of the `access-denied-handler` child element.

#### `once-per-request`

Corresponds to the `observeOncePerRequest` property of `FilterSecurityInterceptor`. Defaults to "true".

#### `create-session`

Controls the eagerness with which an HTTP session is created. If not set, defaults to "ifRequired". Other options are "always" and "never". The setting of this attribute affect the `allowSessionCreation` and `forceEagerSessionCreation` properties of `HttpSessionContextIntegrationFilter`. `allowSessionCreation` will always be true unless this attribute is set to "never". `forceEagerSessionCreation` is "false" unless it is set to "always". So the default configuration allows session creation but does not force it. The exception is if concurrent session control is enabled, when `forceEagerSessionCreation` will be set to true, regardless of what the setting is here. Using "never" would then cause an exception during the initialization of `HttpSessionContextIntegrationFilter`.

#### `use-expressions`

Enables EL-expressions in the `access` attribute, as described in the chapter on expression-based access-control.

#### `disable-url-rewriting`

Prevents session IDs from being appended to URLs in the application. Clients must use cookies if this attribute is set to `true`.

### `<access-denied-handler>`

This element allows you to set the `errorPage` property for the default AccessDeniedHandler used by the `ExceptionTranslationFilter`, (using the `error-page` attribute, or to supply your own implementation using the `ref` attribute. This is discussed in more detail in the section on the `ExceptionTranslationFilter`.

### The `<intercept-url>` Element

This element is used to define the set of URL patterns that the application is interested in and to configure how they should be handled. It is used to construct the FilterInvocationSecurityMetadataSource used by the `FilterSecurityInterceptor`. It is also responsible for configuring a `ChannelAuthenticationFilter` if particular URLs need to be accessed by HTTPS, for example. When matching the specified patterns against an incoming request, the matching is done in the order in which the elements are declared. So the most specific matches patterns should come first and the most general should come last.

#### `pattern`

The pattern which defines the URL path. The content will depend on the `request-matcher` attribute from the containing http element, so will default to ant path syntax.

#### `method`

The HTTP Method which will be used in combination with the pattern to match an incoming request. If omitted, any method will match. If an identical pattern is specified with and without a method, the method-specific match will take precedence.

#### `access`

Lists the access attributes which will be stored in the FilterInvocationSecurityMetadataSource for the defined URL pattern/method combination. This should be a comma-separated list of the security configuration attributes (such as role names).

#### `requires-channel`

Can be http or https depending on whether a particular URL pattern should be accessed over HTTP or HTTPS respectively. Alternatively the value any can be used when there is no preference. If this attribute is present on any `<intercept-url>` element, then a `ChannelAuthenticationFilter` will be added to the filter stack and its additional dependencies added to the application context.

If a `<port-mappings>` configuration is added, this will be used to by the `SecureChannelProcessor` and `InsecureChannelProcessor` beans to determine the ports used for redirecting to HTTP/HTTPS.

#### `filters`

Can only take the value none. This will cause any matching request to bypass the Spring Security filter chain entirely. None of the rest of the `<http>` configuration will have any effect on the request and there will be no security context available for its duration. Access to secured methods during the request will fail.

### The `<port-mappings>` Element

By default, an instance of `PortMapperImpl` will be added to the configuration for use in redirecting to secure and insecure URLs. This element can optionally be used to override the default mappings which that class defines. Each child `<port-mapping>` element defines a pair of HTTP:HTTPS ports. The default mappings are 80:443 and 8080:8443. An example of overriding these can be found in the namespace introduction.

### The `<form-login>` Element

Used to add an `UsernamePasswordAuthenticationFilter` to the filter stack and an `LoginUrlAuthenticationEntryPoint` to the application context to provide authentication on demand. This will always take precedence over other namespace-created entry points. If no attributes are supplied, a login page will be generated automatically at the URL "/spring-security-login" This feature is really just provided for convenience and is not intended for production (where a view technology will have been chosen and can be used to render a customized login page). The class `DefaultLoginPageGeneratingFilter` is responsible for rendering the login page and will provide login forms for both normal form login and/or OpenID if required. The behaviour can be customized using the following attributes.

#### `login-page`

The URL that should be used to render the login page. Maps to the `loginFormUrl` property of the `LoginUrlAuthenticationEntryPoint`. Defaults to "/spring-security-login".

#### `login-processing-url`

Maps to the `filterProcessesUrl` property of `UsernamePasswordAuthenticationFilter`. The default value is "/j_spring_security_check".

#### `default-target-url`

Maps to the `defaultTargetUrl` property of `UsernamePasswordAuthenticationFilter`. If not set, the default value is "/" (the application root). A user will be taken to this URL after logging in, provided they were not asked to login while attempting to access a secured resource, when they will be taken to the originally requested URL.

#### `always-use-default-target`

If set to "true", the user will always start at the value given by `default-target-url`, regardless of how they arrived at the login page. Maps to the `alwaysUseDefaultTargetUrl` property of `UsernamePasswordAuthenticationFilter`. Default value is "false".

#### `authentication-failure-url`

Maps to the `authenticationFailureUrl` property of `UsernamePasswordAuthenticationFilter`. Defines the URL the browser will be redirected to on login failure. Defaults to "/spring_security_login?login_error", which will be automatically handled by the automatic login page generator, re-rendering the login page with an error message.

#### `authentication-success-handler-ref`

This can be used as an alternative to `default-target-url` and `always-use-default-target`, giving you full control over the navigation flow after a successful authentication. The value should be the name of an AuthenticationSuccessHandler bean in the application context. By default, an imlementation of `SavedRequestAwareAuthenticationSuccessHandler` is used and injected with the `default-target-url`.

#### `authentication-failure-handler-ref`

Can be used as an alternative to `authentication-failure-url`, giving you full control over the navigation flow after an authentication failure. The value should be he name of an AuthenticationFailureHandler bean in the application context.

### The `<http-basic>` Element

Adds a `BasicAuthenticationFilter` and `BasicAuthenticationEntryPoint` to the configuration. The latter will only be used as the configuration entry point if form-based login is not enabled.

### The `<remember-me>` Element

Adds the `RememberMeAuthenticationFilter` to the stack. This in turn will be configured with either a `TokenBasedRememberMeServices`, a `PersistentTokenBasedRememberMeServices` or a user-specified bean implementing RememberMeServices depending on the attribute settings.

#### `data-source-ref`

If this is set, `PersistentTokenBasedRememberMeServices` will be used and configured with a `JdbcTokenRepositoryImpl` instance.

#### `token-repository-ref`

Configures a `PersistentTokenBasedRememberMeServices` but allows the use of a custom PersistentTokenRepository bean.

#### `services-ref`

Allows complete control of the RememberMeServices implementation that will be used by the filter. The value should be the Id of a bean in the application context which implements this interface.

#### `token-repository-ref`

Configures a `PersistentTokenBasedRememberMeServices` but allows the use of a custom PersistentTokenRepository bean.

#### The `key` Attribute

Maps to the "key" property of `AbstractRememberMeServices`. Should be set to a unique value to ensure that remember-me cookies are only valid within the one application This doesn't affect the use of `PersistentTokenBasedRememberMeServices`, where the tokens are stored on the server side. .

#### `token-validity-seconds`

Maps to the `tokenValiditySeconds` property of `AbstractRememberMeServices`. Specifies the period in seconds for which the remember-me cookie should be valid. By default it will be valid for 14 days.

#### `user-service-ref`

The remember-me services implementations require access to a UserDetailsService, so there has to be one defined in the application context. If there is only one, it will be selected and used automatically by the namespace configuration. If there are multiple instances, you can specify a bean Id explicitly using this attribute.

### The `<session-management>` Element

Session-management related functionality is implemented by the addition of a `SessionManagementFilter` to the filter stack.

#### `session-fixation-protection`

Indicates whether an existing session should be invalidated when a user authenticates and a new session started. If set to "none" no change will be made. "newSession" will create a new empty session. "migrateSession" will create a new session and copy the session attributes to the new session. Defaults to "migrateSession".

If session fixation protection is enabled, the `SessionManagementFilter` is inected with a appropriately configured `DefaultSessionAuthenticationStrategy`. See the Javadoc for this class for more details.

### The `<concurrency-control>` Element

Adds support for concurrent session control, allowing limits to be placed on the number of active sessions a user can have. A `ConcurrentSessionFilter` will be created, and a `ConcurrentSessionControlStrategy` will be used with the `SessionManagementFilter`. If a `form-login` element has been declared, the strategy object will also be injected into the created authentication filter. An instance of SessionRegistry (a `SessionRegistryImpl` instance unless the user wishes to use a custom bean) will be created for use by the strategy.

#### The `max-sessions` attribute

Maps to the `maximumSessions` property of `ConcurrentSessionControlStrategy`.

#### The `expired-url` attribute

The URL a user will be redirected to if they attempt to use a session which has been "expired" by the concurrent session controller because the user has exceeded the number of allowed sessions and has logged in again elsewhere. Should be set unless `exception-if-maximum-exceeded` is set. If no value is supplied, an expiry message will just be written directly back to the response.

#### The `error-if-maximum-exceeded` attribute

If set to "true" a SessionAuthenticationException will be raised when a user attempts to exceed the maximum allowed number of sessions. The default behaviour is to expire the original session.

#### The `session-registry-alias` and `session-registry-ref` attributes

The user can supply their own SessionRegistry implementation using the `session-registry-ref` attribute. The other concurrent session control beans will be wired up to use it.

It can also be useful to have a reference to the internal session registry for use in your own beans or an admin interface. You can expose the interal bean using the `session-registry-alias` attribute, giving it a name that you can use elsewhere in your configuration.

### The `<anonymous>` Element

Adds an `AnonymousAuthenticationFilter` to the stack and an `AnonymousAuthenticationProvider`. Required if you are using the `IS_AUTHENTICATED_ANONYMOUSLY` attribute.

### The `<x509>` Element

Adds support for X.509 authentication. An `X509AuthenticationFilter` will be added to the stack and an `Http403ForbiddenEntryPoint` bean will be created. The latter will only be used if no other authentication mechanisms are in use (it's only functionality is to return an HTTP 403 error code). A `PreAuthenticatedAuthenticationProvider` will also be created which delegates the loading of user authorities to a UserDetailsService.

#### The `subject-principal-regex` attribute

Defines a regular expression which will be used to extract the username from the certificate (for use with the UserDetailsService).

#### The `user-service-ref` attribute

Allows a specific UserDetailsService to be used with X.509 in the case where multiple instances are configured. If not set, an attempt will be made to locate a suitable instance automatically and use that.

### The `<openid-login>` Element

Similar to `<form-login>` and has the same attributes. The default value for `login-processing-url` is "/j_spring_openid_security_check". An `OpenIDAuthenticationFilter` and `OpenIDAuthenticationProvider` will be registered. The latter requires a reference to a UserDetailsService. Again, this can be specified by Id, using the `user-service-ref` attribute, or will be located automatically in the application context.

#### The `<attribute-exchange>` Element

The `attribute-exchange` element defines the list of attributes which should be requested from the identity provider. More than one can be used, in which case each must have an `identifier-match` attribute, containing a regular expression which is matched against the supplied OpenID identifer. This allows different attribute lists to be fetched from different providers (Google, Yahoo etc).

### The `<logout>` Element

Adds a `LogoutFilter` to the filter stack. This is configured with a `SecurityContextLogoutHandler`.

#### The `logout-url` attribute

The URL which will cause a logout (i.e. which will be processed by the filter). Defaults to "/j_spring_security_logout".

#### The `logout-success-url` attribute

The destination URL which the user will be taken to after logging out. Defaults to "/".

#### The `invalidate-session` attribute

Maps to the `invalidateHttpSession` of the `SecurityContextLogoutHandler`. Defaults to "true", so the session will be invalidated on logout.

### The `<custom-filter>` Element

This element is used to add a filter to the filter chain. It doesn't create any additional beans but is used to select a bean of type javax.servlet.Filter which is already defined in the appllication context and add that at a particular position in the filter chain maintained by Spring Security. Full details can be found in the namespace chapter.

### The `request-cache` Element

Sets the RequestCache instance which will be used by the `ExceptionTranslationFilter` to store request information before invoking an AuthenticationEntryPoint.

## Authentication Services

Before Spring Security 3.0, an AuthenticationManager was automatically registered internally. Now you must register one explicitly using the `<authentication-manager>` element. This creates an instance of Spring Security's `ProviderManager` class, which needs to be configured with a list of one or more AuthenticationProvider instances. These can either be created using syntax elements provided by the namespace, or they can be standard bean definitions, marked for addition to the list using the `authentication-provider` element.

### The `<authentication-manager>` Element

Every Spring Security application which uses the namespace must have include this element somewhere. It is responsible for registering the AuthenticationManager which provides authentication services to the application. It also allows you to define an alias name for the internal instance for use in your own configuration. Its use is described in the namespace introduction. All elements which create AuthenticationProvider instances should be children of this element.

The element also exposes an `erase-credentials` attribute which maps to the `eraseCredentialsAfterAuthentication` property of the `ProviderManager`. This is discussed in the Core Services chapter.

#### The `<authentication-provider>` Element

Unless used with a `ref` attribute, this element is shorthand for configuring a `DaoAuthenticationProvider`. `DaoAuthenticationProvider` loads user information from a UserDetailsService and compares the username/password combination with the values supplied at login. The UserDetailsService instance can be defined either by using an available namespace element (`jdbc-user-service` or by using the `user-service-ref` attribute to point to a bean defined elsewhere in the application context). You can find examples of these variations in the namespace introduction.

##### The `<password-encoder>` Element

Authentication providers can optionally be configured to use a password encoder as described in the namespace introduction. This will result in the bean being injected with the appropriate PasswordEncoder instance, potentially with an accompanying SaltSource bean to provide salt values for hashing.

#### Using `<authentication-provider>` to refer to an AuthenticationProvider Bean

If you have written your own AuthenticationProvider implementation (or want to configure one of Spring Security's own implementations as a traditional bean for some reason, then you can use the following syntax to add it to the internal `ProviderManager`'s list:

      <security:authentication-manager>
        <security:authentication-provider ref="myAuthenticationProvider" />
      </security:authentication-manager>
      <bean id="myAuthenticationProvider" class="com.something.MyAuthenticationProvider"/>

## Method Security

### The `<global-method-security>` Element

This element is the primary means of adding support for securing methods on Spring Security beans. Methods can be secured by the use of annotations (defined at the interface or class level) or by defining a set of pointcuts as child elements, using AspectJ syntax.

Method security uses the same AccessDecisionManager configuration as web security, but this can be overridden as explained above , using the same attribute.

#### The `secured-annotations` and `jsr250-annotations` Attributes

Setting these to "true" will enable support for Spring Security's own `@Secured` annotations and JSR-250 annotations, respectively. They are both disabled by default. Use of JSR-250 annotations also adds a `Jsr250Voter` to the AccessDecisionManager, so you need to make sure you do this if you are using a custom implementation and want to use these annotations.

#### The `mode` Attribute

This attribute can be set to aspectj to specify that AspectJ should be used instead of the default Spring AOP. Secured methods must be woven with the `AnnotationSecurityAspect` from the `spring-security-aspects` module.

#### Securing Methods using `<protect-pointcut>`

Rather than defining security attributes on an individual method or class basis using the `@Secured` annotation, you can define cross-cutting security constraints across whole sets of methods and interfaces in your service layer using the `<protect-pointcut>` element. This has two attributes:

- `expression` - the pointcut expression

- `access` - the security attributes which apply

You can find an example in the namespace introduction.

#### The `<after-invocation-provider>` Element

This element can be used to decorate an AfterInvocationProvider for use by the security interceptor maintained by the `<global-method-security>` namespace. You can define zero or more of these within the `global-method-security` element, each with a `ref` attribute pointing to an AfterInvocationProvider bean instance within your application context.

### LDAP Namespace Options

LDAP is covered in some details in its own chapter. We will expand on that here with some explanation of how the namespace options map to Spring beans. The LDAP implementation uses Spring LDAP extensively, so some familiarity with that project's API may be useful.

#### Defining the LDAP Server using the `<ldap-server>` Element

This element sets up a Spring LDAP ContextSource for use by the other LDAP beans, defining the location of the LDAP server and other information (such as a username and password, if it doesn't allow anonymous access) for connecting to it. It can also be used to create an embedded server for testing. Details of the syntax for both options are covered in the LDAP chapter. The actual ContextSource implementation is `DefaultSpringSecurityContextSource` which extends Spring LDAP's `LdapContextSource` class. The `manager-dn` and `manager-password` attributes map to the latter's `userDn` and `password` properties respectively.

If you only have one server defined in your application context, the other LDAP namespace-defined beans will use it automatically. Otherwise, you can give the element an "id" attribute and refer to it from other namespace beans using the `server-ref` attribute. This is actually the bean Id of the `ContextSource` instance, if you want to use it in other traditional Spring beans.

#### The `<ldap-provider>` Element

This element is shorthand for the creation of an `LdapAuthenticationProvider` instance. By default this will be configured with a `BindAuthenticator` instance and a `DefaultAuthoritiesPopulator`. As with all namespace authentication providers, it must be included as a child of the `authentication-provider` element.

##### The `user-dn-pattern` Attribute

If your users are at a fixed location in the directory (i.e. you can work out the DN directly from the username without doing a directory search), you can use this attribute to map directly to the DN. It maps directly to the `userDnPatterns` property of `AbstractLdapAuthenticator`.

##### The `user-search-base` and `user-search-filter` Attributes

If you need to perform a search to locate the user in the directory, then you can set these attributes to control the search. The `BindAuthenticator` will be configured with a `FilterBasedLdapUserSearch` and the attribute values map directly to the first two arguments of that bean's constructor. If these attributes aren't set and no `user-dn-pattern` has been supplied as an alternative, then the default search values of `user-search-filter="(uid={0})"` and `user-search-base=""` will be used.

##### `group-search-filter`, `group-search-base`, `group-role-attribute` and `role-prefix` Attributes

The value of `group-search-base` is mapped to the `groupSearchBase` constructor argument of `DefaultAuthoritiesPopulator` and defaults to "ou=groups". The default filter value is "(uniqueMember={0})", which assumes that the entry is of type "groupOfUniqueNames". `group-role-attribute` maps to the `groupRoleAttribute` attribute and defaults to "cn". Similarly `role-prefix` maps to `rolePrefix` and defaults to "ROLE_".

##### The `<password-compare>` Element

This is used as child element to `<ldap-provider>` and switches the authentication strategy from `BindAuthenticator` to `PasswordComparisonAuthenticator`. This can optionally be supplied with a `hash` attribute or with a child `<password-encoder>` element to hash the password before submitting it to the directory for comparison.

#### The `<ldap-user-service>` Element

This element configures an LDAP UserDetailsService. The class used is `LdapUserDetailsService` which is a combination of a `FilterBasedLdapUserSearch` and a `DefaultAuthoritiesPopulator`. The attributes it supports have the same usage as in `<ldap-provider>`.