Creating New Roles and Permissions Dynamically in Spring Security 3

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So these are at least two questions:

  • How to make the granted authorities/privileges/Roles dynamic?
  • How to make the access restriction for the URLs dynamic?

1) How to make the granted authorities/privileges/Roles dynamic?

I will not answer this in great detail, because I believe this theme was discussed often enough.

The easiest way would be to store the complete user information (login, password and roles) in a database (3 Tables: User, Roles, User2Roles) and use the JdbcDetailService. You can configure the two SQL Statements (for authentication and for granting the roles) very nicely in your xml configuration.

But then the user needs to logout and login to get these new Roles. If this is not acceptable, you must also manipulate the Roles of the current logged in user. They are stored in the users session. I guess the easiest way to do that is to add a filter in the spring security filter chain that updates the Roles for every request, if they need to be changed.

2) How to make the access restriction for the URLs dynamic?

Here you have at last two ways:

  • Hacking into the FilterSecurityInterceptor and updating the securityMetadataSource, the needed Roles should be stored there. At least you must manipulate the output of the method DefaultFilterInvocationSecurityMetadataSource#lookupAttributes(String url, String method)
  • The other way would be using other expressions for the access attribute instead of access="hasRole('ROLE_USER')". Example: access="isAllowdForUserPages1To3". Of course you must create that method. This is called a “custom SpEL expression handler” (If you have the Spring Security 3 Book it’s around page 210. Wish they had chapter numbers!). So what you need to do now is to subclass WebSecurityExpressionRoot and introduce a new method isAllowdForUserPages1To3. Then you need to subclass DefaultWebSecurityExpressionHandler and modify the createEvaluationContext method so that its first request StandartEvaluationContext calls super (you need to cast the result to StandartEvaluationContext). Then, replace the rootObject in the StandartEvaluationContext using your new CustomWebSecurityExpressionRoot implementation. That’s the hard part! Then, you need to replace the expressionHandler attribute of the expressionVoter (WebExpressionVoter) in the xml configuration with your new subclassed DefaultWebSecurityExpressionHandler. (This sucks because you first need to write a lot of security configuration explicity as you can’t access them directly from the security namespace.)

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