I usually post about Security on Twitter - you can follow me there:
Spring Security provides several mechanisms to configure a request pattern as unsecured, or allowing all access. Depending on each of these mechanisms – this can either mean not running the security filter chain on that path at all, or running the filter chain and allowing access.
Setting up an <intercept-url> element with access=”permitAll” will configure the authorization so that all requests are allowed on that particular path:
<intercept-url pattern="/login*" access="permitAll" />
This is achieved without disabling the security filters – these still run, so any Spring Security related functionality will still be available.
This is a pre-Spring 3.1 feature that has been deprecated and replaced in Spring 3.1.
The filters attribute disables the Spring Security filters chain entirely on that particular request path:
<intercept-url pattern="/login*" filters="none" />
This may cause problems when the processing of the request will require some functionality of Spring Security.
Since this is a deprecated feature Spring versions newer than 3.0, using it with Spring 3.1 will result in an runtime exception on startup:
SEVERE: Context initialization failed org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Configuration problem: The use of "filters='none'" is no longer supported. Please define a separate <http> element for the pattern you want to exclude and use the attribute "security='none'". Offending resource: class path resource [webSecurityConfig.xml] at o.s.b.f.p.FailFastProblemReporter.error(FailFastProblemReporter.java:68)
As we saw in the error message above, Spring 3.1 replaces filters=”none” with a new expression – security=”none”.
The scope has changed as well – this is no longer specified at the <intercept-url> element level. Instead, Spring 3.1 allows multiple <http> elements to be defined – each with it’s own security filter chain configuration. And so, the new security attribute now belongs on at <http> element level.
In practice, this will look like:
<http pattern="/resources/**" security="none"/>
Instead of the old:
<intercept-url pattern="/resources/**" filters="none"/>
Similar to filters=”none”, this will also completely disable the Security filter chain for that request path – so when the request is handled in the application, Spring Security features will not be available.
This is not a problem for the examples above, which mainly deal with serving static resources – where no actual processing takes place. However, if the request is handled programatically in some way – then security functionalities such as requires-channel, accessing the current user or calling secured methods will not be available.
For the same reason, there is no point specifying additional attributes on an <http> element that has already been configured with security=”none” because that request path is unsecured and the attributes will simply be ignored.
Alternatively, access=’IS_AUTHENTICATED_ANONYMOUSLY’ can be used to allow anonymous access.
5. Caveats for security=”none”
When using multiple <http> elements, some configured with security=”none”, keep in mind that the order in which these elements are defined is important. We want to have the specific <http> paths first, followed universal pattern at the very end.
Also note that, if an <http> element doesn’t specify a pattern, then by default, that maps to the universal match pattern – “/**” – so again, this element needs to be last. If the order of the elements is not correct, the creation of the security filter chain will fail:
Caused by: java.lang.IllegalArgumentException: A universal match pattern ('/**') is defined before other patterns in the filter chain, causing them to be ignored. Please check the ordering in your <security:http> namespace or FilterChainProxy bean configuration at o.s.s.c.h.DefaultFilterChainValidator.checkPathOrder(DefaultFilterChainValidator.java:49) at o.s.s.c.h.DefaultFilterChainValidator.validate(DefaultFilterChainValidator.java:39)
This article discusses the options of allowing access to a path with Spring Security – focusing on the differences between filters=”none”, security=”none” and access=”permitAll”.
The implementation of this simple project can be found in the github project – this is an Eclipse based project, so it should be easy to import and run as it is.