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Given a code listing, determine whether it is a legal and appropriate way to programmatically access a caller's security context.

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This page discusses - Given a code listing, determine whether it is a legal and appropriate way to programmatically access a caller's security context.

Given a code listing, determine whether it is a legal and appropriate way to programmatically access a caller's security context.

The javax.ejb.EJBContext interface provides TWO methods that allow the Bean Provider to access security information about the enterprise bean's caller:

package javax.ejb;

public interface EJBContext {

	// The following two methods allow the EJB class
	// to access security information:

	// Returns the principal that represents the CALLER of the
	// enterprise bean, not the principal that corresponds to the 
	// run-as security identity for the bean, if any.
	java.security.Principal getCallerPrincipal();

	// Tests the principal that represents the CALLER of the
	// enterprise bean, not the principal that corresponds
	// to the run-as security identity for the bean, if any.
	boolean isCallerInRole(String roleName);
	...	
}
					

The Bean Provider can invoke the getCallerPrincipal and isCallerInRole methods only in the enterprise bean's business methods for which the Container has a client SECURITY CONTEXT.

The purpose of the getCallerPrincipal() method is to allow the enterprise bean methods to obtain the current caller principal's name. The methods might, for example, use the name as a key to information in a database.

An enterprise bean can invoke the getCallerPrincipal() method to obtain a java.security.Principal interface representing the current caller. The enterprise bean can then obtain the distinguished name of the caller principal using the getName() method of the java.security.Principal interface.

public class EmployeeServiceBean implements SessionBean {
	EJBContext ejbContext;

	public void changePhoneNumber(...) {
		...
		// Obtain the default initial JNDI context.
		Context initCtx = new InitialContext();

		// Look up the remote home interface of the EmployeeRecord
		// enterprise bean in the environment.
		Object result = initCtx.lookup("java:comp/env/ejb/EmplRecord");

		// Convert the result to the proper type.
		EmployeeRecordHome emplRecordHome = (EmployeeRecordHome)
			javax.rmi.PortableRemoteObject.narrow(result,
			EmployeeRecordHome.class);

		// obtain the caller principal.
		callerPrincipal = ejbContext.getCallerPrincipal();

		// obtain the caller principal's name.
		callerKey = callerPrincipal.getName();

		// use callerKey as primary key to EmployeeRecord finder
		EmployeeRecord myEmployeeRecord =
			emplRecordHome.findByPrimaryKey(callerKey);

		// update phone number
		myEmployeeRecord.changePhoneNumber(...);
	...
	}
}
					

The enterprise bean code uses the isCallerInRole(String roleName) method to test whether the current caller has been assigned to a given security role. Security roles are defined by the Application Assembler in the deployment descriptor, and are assigned to principals or principal groups that exist in the operational environment by the Deployer.


public class PayrollBean ... {
	EntityContext ejbContext;

	public void updateEmployeeInfo(EmplInfo info) {

		oldInfo = ... // read from database;

		// The salary field can be changed only by callers
		// who have the security role "payroll"
		if (info.salary != oldInfo.salary &&
		!ejbContext.isCallerInRole("payroll")) {
			throw new SecurityException(...);
		}
		...
	}
...
}

					

The Bean Provider is responsible for DECLARING in the security-role-ref elements of the deployment descriptor all the security role names used in the enterprise bean code. The ROLE NAME name must be the security role name that is used as a parameter to the isCallerInRole(String roleName) method.


<entity>
	<ejb-name>AardvarkPayroll</ejb-name>
	<ejb-class>com.aardvark.payroll.PayrollBean</ejb-class>
	...
	<security-role-ref>
		<description>
			This security role should be assigned to the
			employees of the payroll department who are
			allowed to update employees' salaries.
		</description>
		<role-name>payroll</role-name>
	</security-role-ref>
	...
</entity>

					

Full description of security-role-ref element is:


<!--
The security-role-ref element contains the declaration of a security
role reference in the enterprise bean's code. The declaration consists
of an optional description, the security role name used in the
code, and an optional link to a defined security role.
The value of the role-name element must be the String used as the
parameter to the EJBContext.isCallerInRole(String roleName) method.
The value of the role-link element must be the name of one of the
security roles defined in the security-role elements.
Used in: entity and session
-->

<!ELEMENT security-role-ref (description?, role-name, role-link?)>

					

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Posted on: April 18, 2011 If you enjoyed this post then why not add us on Google+? Add us to your Circles

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