org.owasp.esapi

Interface AccessController

All Known Implementing Classes:

DefaultAccessController, ExperimentalAccessController

public interface AccessController

The AccessController interface defines a set of methods that can be used in a wide variety of applications to enforce access control. In most applications, access control must be performed in multiple different locations across the various application layers. This class provides access control for URLs, business functions, data, services, and files.

The implementation of this interface will need to access the current User object (from Authenticator.getCurrentUser()) to determine roles or permissions. In addition, the implementation will also need information about the resources that are being accessed. Using the user information and the resource information, the implementation should return an access control decision.

Implementers are encouraged to implement the ESAPI access control rules, like assertAuthorizedForFunction() using existing access control mechanisms, such as methods like isUserInRole() or hasPrivilege(). While powerful, methods like isUserInRole() can be confusing for developers, as users may be in multiple roles or possess multiple overlapping privileges. Direct use of these finer grained access control methods encourages the use of complex boolean tests throughout the code, which can easily lead to developer mistakes.

The point of the ESAPI access control interface is to centralize access control logic behind easy to use calls like assertAuthorized() so that access control is easy to use and easy to verify. Here is an example of a very straightforward to implement, understand, and verify ESAPI access control check:

 try {
     ESAPI.accessController().assertAuthorized("businessFunction", runtimeData);
     // execute BUSINESS_FUNCTION
 } catch (AccessControlException ace) {
 ... attack in progress
 }
 

Note that in the user interface layer, access control checks can be used to control whether particular controls are rendered or not. These checks are supposed to fail when an unauthorized user is logged in, and do not represent attacks. Remember that regardless of how the user interface appears, an attacker can attempt to invoke any business function or access any data in your application. Therefore, access control checks in the user interface should be repeated in both the business logic and data layers.

 <% if ( ESAPI.accessController().isAuthorized( "businessFunction", runtimeData ) ) { %>
 <a href="/doAdminFunction">ADMIN</a>
 <% } else { %>
 <a href="/doNormalFunction">NORMAL</a>
 <% } %>
 

Method Summary

Modifier and Type	Method and Description
void	assertAuthorized(java.lang.Object key, java.lang.Object runtimeParameter) assertAuthorized executes the AccessControlRule that is identified by key and listed in the resources/ESAPI-AccessControlPolicy.xml file.
void	assertAuthorizedForData(java.lang.String action, java.lang.Object data) Checks if the current user is authorized to access the referenced data.
void	assertAuthorizedForFile(java.lang.String filepath) Checks if the current user is authorized to access the referenced file.
void	assertAuthorizedForFunction(java.lang.String functionName) Checks if the current user is authorized to access the referenced function.
void	assertAuthorizedForService(java.lang.String serviceName) Checks if the current user is authorized to access the referenced service.
void	assertAuthorizedForURL(java.lang.String url) Checks if the current user is authorized to access the referenced URL.
boolean	isAuthorized(java.lang.Object key, java.lang.Object runtimeParameter) isAuthorized executes the AccessControlRule that is identified by key and listed in the resources/ESAPI-AccessControlPolicy.xml file.
boolean	isAuthorizedForData(java.lang.String action, java.lang.Object data) Checks if the current user is authorized to access the referenced data, represented as an Object.
boolean	isAuthorizedForFile(java.lang.String filepath) Checks if the current user is authorized to access the referenced file.
boolean	isAuthorizedForFunction(java.lang.String functionName) Checks if the current user is authorized to access the referenced function.
boolean	isAuthorizedForService(java.lang.String serviceName) Checks if the current user is authorized to access the referenced service.
boolean	isAuthorizedForURL(java.lang.String url) Checks if the current user is authorized to access the referenced URL.

Method Detail

isAuthorized

boolean isAuthorized(java.lang.Object key,
                     java.lang.Object runtimeParameter)

isAuthorized executes the AccessControlRule that is identified by key and listed in the resources/ESAPI-AccessControlPolicy.xml file. It returns true if the AccessControlRule decides that the operation should be allowed. Otherwise, it returns false. Any exception thrown by the AccessControlRule must result in false. If key does not map to an AccessControlRule, then false is returned. Developers should call isAuthorized to control execution flow. For example, if you want to decide whether to display a UI widget in the browser using the same logic that you will use to enforce permissions on the server, then isAuthorized is the method that you want to use. Typically, assertAuthorized should be used to enforce permissions on the server.

Parameters:

key - key maps to <AccessControlPolicy><AccessControlRules> <AccessControlRule name="key"

runtimeParameter - runtimeParameter can contain anything that the AccessControlRule needs from the runtime system.

Returns:

Returns true if and only if the AccessControlRule specified by key exists and returned true. Otherwise returns false

assertAuthorized

void assertAuthorized(java.lang.Object key,
                      java.lang.Object runtimeParameter)
               throws AccessControlException

assertAuthorized executes the AccessControlRule that is identified by key and listed in the resources/ESAPI-AccessControlPolicy.xml file. It does nothing if the AccessControlRule decides that the operation should be allowed. Otherwise, it throws an org.owasp.esapi.errors.AccessControlException. Any exception thrown by the AccessControlRule will also result in an AccesControlException. If key does not map to an AccessControlRule, then an AccessControlException is thrown. Developers should call assertAuthorized to enforce privileged access to the system. It should be used to answer the question: "Should execution continue." Ideally, the call to assertAuthorized should be integrated into the application framework so that it is called automatically.

Parameters:

key - key maps to <AccessControlPolicy><AccessControlRules> <AccessControlRule name="key"

runtimeParameter - runtimeParameter can contain anything that the AccessControlRule needs from the runtime system.

Throws:

AccessControlException

isAuthorizedForURL

boolean isAuthorizedForURL(java.lang.String url)

Checks if the current user is authorized to access the referenced URL. Generally, this method should be invoked in the application's controller or a filter as follows:

ESAPI.accessController().isAuthorizedForURL(request.getRequestURI().toString());

The implementation of this method should call assertAuthorizedForURL(String url), and if an AccessControlException is not thrown, this method should return true. This way, if the user is not authorized, false would be returned, and the exception would be logged.

Parameters:

url - the URL as returned by request.getRequestURI().toString()

Returns:

true, if is authorized for URL

isAuthorizedForFunction

boolean isAuthorizedForFunction(java.lang.String functionName)

Checks if the current user is authorized to access the referenced function. The implementation of this method should call assertAuthorizedForFunction(String functionName), and if an AccessControlException is not thrown, this method should return true.

Parameters:

functionName - the name of the function

Returns:

true, if is authorized for function

isAuthorizedForData

boolean isAuthorizedForData(java.lang.String action,
                            java.lang.Object data)

Checks if the current user is authorized to access the referenced data, represented as an Object. The implementation of this method should call assertAuthorizedForData(String action, Object data), and if an AccessControlException is not thrown, this method should return true.

Parameters:

action - The action to verify for an access control decision, such as a role, or an action being performed on the object (e.g., Read, Write, etc.), or the name of the function the data is being passed to.

data - The actual object or object identifier being accessed or a reference to the object being accessed.

Returns:

true, if is authorized for the data

isAuthorizedForFile

boolean isAuthorizedForFile(java.lang.String filepath)

Checks if the current user is authorized to access the referenced file. The implementation of this method should call assertAuthorizedForFile(String filepath), and if an AccessControlException is not thrown, this method should return true.

Parameters:

filepath - the path of the file to be checked, including filename

Returns:

true, if is authorized for the file

isAuthorizedForService

boolean isAuthorizedForService(java.lang.String serviceName)

Checks if the current user is authorized to access the referenced service. This can be used in applications that provide access to a variety of back end services. The implementation of this method should call assertAuthorizedForService(String serviceName), and if an AccessControlException is not thrown, this method should return true.

Parameters:

serviceName - the service name

Returns:

true, if is authorized for the service

assertAuthorizedForURL

void assertAuthorizedForURL(java.lang.String url)
                     throws AccessControlException

Checks if the current user is authorized to access the referenced URL. The implementation should allow access to be granted to any part of the URL. Generally, this method should be invoked in the application's controller or a filter as follows:

ESAPI.accessController().assertAuthorizedForURL(request.getRequestURI().toString());

This method throws an AccessControlException if access is not authorized, or if the referenced URL does not exist. If the User is authorized, this method simply returns.

Specification: The implementation should do the following:

1. Check to see if the resource exists and if not, throw an AccessControlException
2. Use available information to make an access control decision
1. Ideally, this policy would be data driven
2. You can use the current User, roles, data type, data name, time of day, etc.
3. Access control decisions must deny by default
3. If access is not permitted, throw an AccessControlException with details

Parameters:

url - the URL as returned by request.getRequestURI().toString()

Throws:

AccessControlException - if access is not permitted

assertAuthorizedForFunction

void assertAuthorizedForFunction(java.lang.String functionName)
                          throws AccessControlException

Checks if the current user is authorized to access the referenced function. The implementation should define the function "namespace" to be enforced. Choosing something simple like the class name of action classes or menu item names will make this implementation easier to use.

This method throws an AccessControlException if access is not authorized, or if the referenced function does not exist. If the User is authorized, this method simply returns.

Specification: The implementation should do the following:

1. Check to see if the function exists and if not, throw an AccessControlException
2. Use available information to make an access control decision
1. Ideally, this policy would be data driven
2. You can use the current User, roles, data type, data name, time of day, etc.
3. Access control decisions must deny by default
3. If access is not permitted, throw an AccessControlException with details

Parameters:

functionName - the function name

Throws:

AccessControlException - if access is not permitted

assertAuthorizedForData

void assertAuthorizedForData(java.lang.String action,
                             java.lang.Object data)
                      throws AccessControlException

Checks if the current user is authorized to access the referenced data. This method simply returns if access is authorized. It throws an AccessControlException if access is not authorized, or if the referenced data does not exist.

Specification: The implementation should do the following:

1. Check to see if the resource exists and if not, throw an AccessControlException
2. Use available information to make an access control decision
1. Ideally, this policy would be data driven
2. You can use the current User, roles, data type, data name, time of day, etc.
3. Access control decisions must deny by default
3. If access is not permitted, throw an AccessControlException with details

Parameters:

action - The action to verify for an access control decision, such as a role, or an action being performed on the object (e.g., Read, Write, etc.), or the name of the function the data is being passed to.

data - The actual object or object identifier being accessed or a reference to the object being accessed.

Throws:

AccessControlException - if access is not permitted

assertAuthorizedForFile

void assertAuthorizedForFile(java.lang.String filepath)
                      throws AccessControlException

Checks if the current user is authorized to access the referenced file. The implementation should validate and canonicalize the input to be sure the filepath is not malicious.

This method throws an AccessControlException if access is not authorized, or if the referenced File does not exist. If the User is authorized, this method simply returns.

Specification: The implementation should do the following:

1. Check to see if the File exists and if not, throw an AccessControlException
2. Use available information to make an access control decision
1. Ideally, this policy would be data driven
2. You can use the current User, roles, data type, data name, time of day, etc.
3. Access control decisions must deny by default
3. If access is not permitted, throw an AccessControlException with details

Parameters:

filepath - Path to the file to be checked

Throws:

AccessControlException - if access is denied

assertAuthorizedForService

void assertAuthorizedForService(java.lang.String serviceName)
                         throws AccessControlException

Checks if the current user is authorized to access the referenced service. This can be used in applications that provide access to a variety of backend services.

This method throws an AccessControlException if access is not authorized, or if the referenced service does not exist. If the User is authorized, this method simply returns.

Specification: The implementation should do the following:

1. Check to see if the service exists and if not, throw an AccessControlException
2. Use available information to make an access control decision
1. Ideally, this policy would be data driven
2. You can use the current User, roles, data type, data name, time of day, etc.
3. Access control decisions must deny by default
3. If access is not permitted, throw an AccessControlException with details

Parameters:

serviceName - the service name

Throws:

AccessControlException - if access is not permitted