JSP Tag Libraries

Declaring the Taglib

To use any of the tags, you must have the security taglib declared in your JSP:

<%@ taglib prefix="sec" uri="http://www.springframework.org/security/tags" %>

The authorize Tag

This tag is used to determine whether its contents should be evaluated or not. In Spring Security 3.0, it can be used in two ways.

The legacy options from Spring Security 2.0 are also supported, but discouraged.

The first approach uses a web-security expression, which is specified in the access attribute of the tag. The expression evaluation is delegated to the SecurityExpressionHandler<FilterInvocation> defined in the application context (you should have web expressions enabled in your <http> namespace configuration to make sure this service is available). So, for example, you might have:

<sec:authorize access="hasRole('supervisor')">

This content will only be visible to users who have the "supervisor" authority in their list of <tt>GrantedAuthority</tt>s.

</sec:authorize>

When used in conjunction with Spring Security’s PermissionEvaluator, the tag can also be used to check permissions:

<sec:authorize access="hasPermission(#domain,'read') or hasPermission(#domain,'write')">

This content will only be visible to users who have read or write permission to the Object found as a request attribute named "domain".

</sec:authorize>

A common requirement is to show only a particular link, assuming the user is actually allowed to click it. How can we determine in advance whether something is allowed? This tag can also operate in an alternative mode that lets you define a particular URL as an attribute. If the user is allowed to invoke that URL, the tag body is evaluated. Otherwise, it is skipped. So you might have something like:

<sec:authorize url="/admin">

This content will only be visible to users who are authorized to send requests to the "/admin" URL.

</sec:authorize>

To use this tag, you must also have an instance of WebInvocationPrivilegeEvaluator in your application context. If you are using the namespace, one is automatically registered. This is an instance of DefaultWebInvocationPrivilegeEvaluator, which creates a dummy web request for the supplied URL and invokes the security interceptor to see whether the request would succeed or fail. This lets you delegate to the access-control setup you defined by using intercept-url declarations within the <http> namespace configuration and saves having to duplicate the information (such as the required roles) within your JSPs. You can also combine this approach with a method attribute (supplying the HTTP method, such as POST) for a more specific match.

You can store the Boolean result of evaluating the tag (whether it grants or denies access) in a page context scope variable by setting the var attribute to the variable name, avoiding the need for duplicating and re-evaluating the condition at other points in the page.

Disabling Tag Authorization for Testing

Hiding a link in a page for unauthorized users does not prevent them from accessing the URL. They could just type it into their browser directly, for example. As part of your testing process, you may want to reveal the hidden areas, to check that links really are secured at the back end. If you set the spring.security.disableUISecurity system property to true, the authorize tag still runs but does not hide its contents. By default, it also surrounds the content with <span class="securityHiddenUI">…</span> tags. This lets you to display “hidden” content with a particular CSS style, such as a different background color. Try running the “tutorial” sample application, for example, with this property enabled.

You can also set the spring.security.securedUIPrefix and spring.security.securedUISuffix properties if you want to change surrounding text from the default span tags (or use empty strings to remove it completely).

The authentication Tag

This tag allows access to the current Authentication object stored in the security context. It renders a property of the object directly in the JSP. So, for example, if the principal property of the Authentication is an instance of Spring Security’s UserDetails object, then using <sec:authentication property="principal.username" /> renders the name of the current user.

Of course, it is not necessary to use JSP tags for this kind of thing, and some people prefer to keep as little logic as possible in the view. You can access the Authentication object in your MVC controller (by calling SecurityContextHolder.getContext().getAuthentication()) and add the data directly to your model for rendering by the view.

The accesscontrollist Tag

This tag is only valid when used with Spring Security’s ACL module. It checks a comma-separated list of required permissions for a specified domain object. If the current user has all of those permissions, the tag body is evaluated. If they do not, it is skipped.

In general, this tag should be considered deprecated. Instead, use the The authorize Tag.

The following listing shows an example:

<sec:accesscontrollist hasPermission="1,2" domainObject="${someObject}">

<!-- This will be shown if the user has all of the permissions represented by the values "1" or "2" on the given object. -->

</sec:accesscontrollist>

The permissions are passed to the PermissionFactory defined in the application context, converting them to ACL Permission instances, so they may be any format that is supported by the factory. They do not have to be integers. They could be strings such as READ or WRITE. If no PermissionFactory is found, an instance of DefaultPermissionFactory is used. The AclService from the application context is used to load the Acl instance for the supplied object. The Acl is invoked with the required permissions to check if all of them are granted.

This tag also supports the var attribute, in the same way as the authorize tag.

The csrfInput Tag

If CSRF protection is enabled, this tag inserts a hidden form field with the correct name and value for the CSRF protection token. If CSRF protection is not enabled, this tag outputs nothing.

Normally, Spring Security automatically inserts a CSRF form field for any <form:form> tags you use, but if for some reason you cannot use <form:form>, csrfInput is a handy replacement.

You should place this tag within an HTML <form></form> block, where you would normally place other input fields. Do NOT place this tag within a Spring <form:form></form:form> block. Spring Security handles Spring forms automatically. The following listing shows an example:

	<form method="post" action="/do/something">
		<sec:csrfInput />
		Name:<br />
		<input type="text" name="name" />
		...
	</form>

The csrfMetaTags Tag

If CSRF protection is enabled, this tag inserts meta tags that contain the CSRF protection token form field and header names and CSRF protection token value. These meta tags are useful for employing CSRF protection within JavaScript in your applications.

You should place csrfMetaTags within an HTML <head></head> block, where you would normally place other meta tags. Once you use this tag, you can access the form field name, header name, and token value by using JavaScript. JQuery is used in this example to make the task easier. The following listing shows an example:

<!DOCTYPE html>
<html>
	<head>
		<title>CSRF Protected JavaScript Page</title>
		<meta name="description" content="This is the description for this page" />
		<sec:csrfMetaTags />
		<script type="text/javascript" language="javascript">

			var csrfParameter = $("meta[name='_csrf_parameter']").attr("content");
			var csrfHeader = $("meta[name='_csrf_header']").attr("content");
			var csrfToken = $("meta[name='_csrf']").attr("content");

			// using XMLHttpRequest directly to send an x-www-form-urlencoded request
			var ajax = new XMLHttpRequest();
			ajax.open("POST", "https://www.example.org/do/something", true);
			ajax.setRequestHeader("Content-Type", "application/x-www-form-urlencoded data");
			ajax.send(csrfParameter + "=" + csrfToken + "&name=John&...");

			// using XMLHttpRequest directly to send a non-x-www-form-urlencoded request
			var ajax = new XMLHttpRequest();
			ajax.open("POST", "https://www.example.org/do/something", true);
			ajax.setRequestHeader(csrfHeader, csrfToken);
			ajax.send("...");

			// using JQuery to send an x-www-form-urlencoded request
			var data = {};
			data[csrfParameter] = csrfToken;
			data["name"] = "John";
			...
			$.ajax({
				url: "https://www.example.org/do/something",
				type: "POST",
				data: data,
				...
			});

			// using JQuery to send a non-x-www-form-urlencoded request
			var headers = {};
			headers[csrfHeader] = csrfToken;
			$.ajax({
				url: "https://www.example.org/do/something",
				type: "POST",
				headers: headers,
				...
			});

		<script>
	</head>
	<body>
		...
	</body>
</html>

If CSRF protection is not enabled, csrfMetaTags outputs nothing.