Service Access Policies

Service access policies comprise a layer of web service security that defines services or service methods that can be invoked remotely. You can apply many of them at once to produce a combined effect. To help you understand how service access policies fit into the big picture, here’s a summary of Liferay DXP’s web service security layers:

IP permission layer: The IP address from which a web service invocation request originates must be white-listed in the portal properties file. A web service invocation coming from a non-whitelisted IP address automatically fails.

Service access policy layer: Methods corresponding to a web service invocation request must be whitelisted by each service access policy that’s in effect. You can use wildcards to reduce the number of service classes and methods that must be explicitly whitelisted.

Authentication/verification layer (browser-only): If a web service invocation request comes from a browser, the request must include an authentication token. This authentication token is the value of the p_auth URL parameter. The token is generated by Liferay DXP and associated with your browser session. The p_auth parameter is automatically supplied when you invoke a Liferay DXP web service via the JSON web services API page or via JavaScript using Liferay.Service(...). If Liferay DXP cannot associate the caller’s authentication token with a User, the web service invocation request fails.

User permission layer: Properly implemented web services have permission checks. The user invoking a web service must have permission to invoke the service.

Figure 1: To get to a service, a request must pass through the door lock of user permissions, the padlock of the verification layer, the brick wall of service access policies, and finally the safe of predefined IP permissions.

Figure 1: To get to a service, a request must pass through the door lock of user permissions, the padlock of the verification layer, the brick wall of service access policies, and finally the safe of predefined IP permissions.

Note that service access policies respect the permissions system. If a service access policy grants a user access to a remote service, the user must still have the appropriate permissions to invoke that service.

Service access policies are especially useful when remote applications such as mobile devices or Liferay Sync instances must access web services. Administrators can use service access policies to ensure that these devices can only invoke remote services from approved lists that can be modified at runtime.

Managing Service Access Policies

Navigate to the Control Panel and click on Service Access Policy under the Configuration heading. Here, you can see the default service access policies and add new ones. When creating or editing service access policies, keep these points in mind:

  • Service access policy names must be unique per portal instance.

  • Service access policy names can include only these allowed characters:

      0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz#:@-./_
    
  • Service access policy titles can be localized; service access policy names cannot be localized.

  • Allowed service signatures must be entered one per line. Wildcards (*) are allowed for both class names and method names. The # symbol must be used to separate a class name from a method name.

For example, com.liferay.portal.kernel.service.UserService allows any method from the UserService class to be invoked. com.liferay.document.library.kernel.service.DLAppService#get* allows any method from the DLAppService that starts with get to be invoked. Thus,

com.liferay.portal.kernel.service.UserService
com.liferay.document.library.kernel.service.DLAppService#get*

allows any method from the UserService class to be invoked and any method from the DLAppService whose name starts with get to be invoked.

There are 16 service access policies that are enabled by default. Six of these have to do with the system:

ASSET_ENTRY_DEFAULT: Allows the view counter for assets to be updated when an asset is retrieved.

CALENDAR_DEFAULT: Makes it possible to search public events in the calendar.

SYNC_DEFAULT: Allows only the com.liferay.sync.service.SyncDLObjectService.getSyncContext method. It applies to every Liferay Sync request, including unauthenticated Sync requests.

SYNC_TOKEN: Allows com.liferay.sync.service.*, meaning that any API function that’s a method of a class in this package can be invoked. It applies to Sync requests which are accompanied by an authentication token.

SYSTEM_DEFAULT: Allows access to country/region services by JavaScript calls, so users can switch languages on the fly. Applies to every request, including unauthenticated requests.

SYSTEM_USER_PASSWORD: Allows any method to be invoked. Of course, since API functions include permission checks, this call works only if the user has the required permission. It applies to requests for which AuthVerifierResult.isPasswordBasedAuthentication is true: i.e., whenever user authentication took place using a password. If you want to completely disallow certain API functions from being invoked, you can change the SYSTEM_USER_PASSWORD policy to something more restrictive than *.

SYNC_DEFAULT and SYSTEM_DEFAULT, as their names suggest, are default service access policies. Default service access policies are applied to all incoming requests, including unauthenticated requests.

The other 10 policies have to do with OAuth and JSON web services:

OAUTH2_analytics.read/write: Integrates with Liferay Analytics Cloud, allowing it access to JSON web services.

OAUTH2_everything/read/documents/userprofile/write: The Everything policies grant access to all the JSON web services for various reasons. Everything is everything: all JSON web services (matches *). The others match method signatures appropriate to their description. For example, OAUTH2_everything.read matches all methods starting with fetch, get, has, is, or search.

OAUTH_READ/WRITE: These provide access to JSON web services via the OAuth 1.0a plugin.

The default configuration makes available corresponding scopes that provide access to all web services shipped with the system. The scopes must be assigned to OAuth 1 or 2 applications before they become usable. Administrators should review the ones you want to use and disable the others.

You can create new default service access policies:

  1. Navigate to the ConfigurationService Access Policy section of the Control Panel.

  2. Click Add (add).

  3. Give your policy a name.

  4. Flip the switch to enable your policy.

  5. If you want the policy applied to unauthenticated requests as well as authenticated requests, flip the switch labeled Default.

  6. Give your policy a localized title.

  7. Under Allowed Service Signatures, start typing the fully qualified name of a service class that’s installed. Code completion helps you find the class. For example, if you’re creating a policy for Liferay’s Knowledge Base application, you could enter com.liferay.knowledge.base.service.KBArticleService.

  8. Under Method Name, start typing a service method call. Again, code completion helps you. For Knowledge Base, you could enter getKBArticle.

  9. To specify another service or method, click the plus icon to add another entry.

  10. When done, click Save.

Liferay applications can declare their own default policies (the SYNC_DEFAULT policy is a good example). This policy can then be changed or disabled by administrators. In this case, the plugin can still verify that the policy exists so there is no need to redefine or update it.

By default, Liferay’s tunneling servlet uses the SYSTEM_USER_PASSWORD service access policy. You can, however, create your own policy for the tunneling servlet and use the property service.access.policy.name for the TunnelingServletAuthVerifier to specify that your policy should be used instead.

Service Access Policy Module

Liferay’s service access policy functionality is provided by the Service Access Policy module. This module includes the following important classes:

  • com.liferay.portal.kernel.security.service.access.policy.ServiceAccessPolicy: defines the public interface for ServiceAccessPolicy.
  • com.liferay.portal.kernel.security.service.access.policy.ServiceAccessPolicyManager: defines the public interface for retrieving instances of ServiceAccessPolicy.
  • com.liferay.portal.kernel.security.service.access.policy.ServiceAccessPolicyManagerUtil: bridges service access policy functionality to the parts of Liferay’s core that have not yet been modularized.
  • com.liferay.portal.kernel.security.service.access.policy.ServiceAccessPolicyThreadLocal: makes ServiceAccessPolicy instances active.

Liferay’s Service Access Policy module resides in the modules/apps/service-access-policy folder in the source code. When running, these three bundles provide the service access policy functionality (they’re in the [Liferay Home]/osgi/modules folder):

  • com.liferay.service.access.policy.api.jar
  • com.liferay.service.access.policy.service.jar
  • com.liferay.service.access.policy.web.jar

These modules provide the service access policy management UI that’s accessible from the Control Panel. They also provide the interface and default implementation for ServiceAccessPolicy.

To configure the Service Access Policy module, navigate to the Control Panel, click on System Settings, and find the Service Access Policies module in the Security section. Click on its name to edit it. Here, you can edit the default service access policy configuration. You can also force a default policy to be applied even when no policies are applied by the AuthVerifier.

There’s also an AuthenticatedAccessControlPolicy. This policy doesn’t do anything if a ServiceAccessPolicyManager implementation is present. If the service access policy module is disabled, however, the AuthenticatedAccessControlPolicy provides a fallback that still requires authenticated access for web services.

Summary

Great! Now you know service access policies can restrict access to Liferay DXP’s web services. Custom service access policies can be created by portal administrators. They are applied by the portal’s token authenticator, e.g., by OAuth.

Creating Service Access Policies

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