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Last update: May 8, 2024

Certainly! Here's the revised version incorporating the suggested improvements:

Scope-based Authorization

Scope-based permissions, also known as imperative or resource-based permissions, depend on the resource being accessed. Consider an order that includes a store property. You may want users to view only the orders belonging to a specific store. Consequently, authorization evaluation must occur after retrieving the order from the data store.

The [Authorize] attribute evaluates permission checks before data binding and executing the API action that loads the order. Due to this, declarative authorization with an [Authorize] attribute alone may not suffice. Instead, you can utilize a custom authorization method, known as imperative authorization.

Define New Permission Scope

Let's explore how resource-based authorization works through the following example:

Suppose we want to restrict user access to orders created in a specific store. To enable this authorization check in the code and assign this permission for end-user roles, follow these steps:

  1. Create a new class named OrderSelectedStoreScope, derived from PermissionScope. This class will hold the store identifier selected by the user in the role management UI.

    public sealed class OrderSelectedStoreScope : PermissionScope
        public string StoreId => Scope;
  2. To register the scope and make the global permission scope-based, add the following code to your Module.cs file:

    public void PostInitialize(IApplicationBuilder appBuilder)
        // Other configurations...
        var permissionsProvider = appBuilder.ApplicationServices.GetRequiredService<IPermissionsRegistrar>();
        permissionsProvider.WithAvailabeScopesForPermissions(new[] {
                                                                    }, new OrderSelectedStoreScope());
        // Other configurations...
  3. Register the presentation template for OrderSelectedStoreScope to allow users to configure permission scope settings in the role manager:

    angular.module(moduleName, []).run( ['platformWebApp.permissionScopeResolver', 'platformWebApp.bladeNavigationService', function(scopeResolver, bladeNavigationService) {
        var orderStoreScope = {
            type: 'OrderSelectedStoreScope',
            title: 'Only for orders in selected stores',
            selectFn: function (blade, callback) {
                var newBlade = {
                    id: 'store-pick',
                    title: this.title,
                    subtitle: 'Select stores',
                    currentEntity: this,
                    onChangesConfirmedFn: callback,
                    dataPromise: stores.query().$promise,
                    controller: '',
                    template: '$(Platform)/Scripts/app/security/blades/common/scope-value-pick-from-simple-list.tpl.html'
                bladeNavigationService.showBlade(newBlade, blade);
    }] );

After these steps, the global order:read permission can be further restricted to work only for selected stores in role assignments.

Write Scope-based Authorization Handler

Writing a handler for a scope-based authorization is not much different from writing a plain requirement handler. You need to create a custom requirement class and implement a requirement handler class derived from PermissionAuthorizationHandlerBase:

public sealed class OrderAuthorizationHandler : PermissionAuthorizationHandlerBase<OrderAuthorizationRequirement>

      protected override async Task HandleRequirementAsync(AuthorizationHandlerContext context, OrderAuthorizationRequirement requirement)
            //Call the base handler first to check the user has a global permission for this action
            await base.HandleRequirementAsync(context, requirement);

            if (!context.HasSucceeded)
                //If we are here, this means the user does not have a global assigned "oder:read" permission, and we need to try to check the scope-based permissions
                var userPermission = context.User.FindPermission(requirement.Permission/*order:read*/, _jsonOptions.SerializerSettings);
                if (userPermission != null)
                    //Read the scopes from the role assignment
                    var storeSelectedScopes = userPermission.AssignedScopes.OfType<OrderSelectedStoreScope>();   
                    //Get all store IDs from scopes                
                    var allowedStoreIds = storeSelectedScopes.Select(x => x.StoreId).Distinct().ToArray();

                    if (context.Resource is OrderOperationSearchCriteriaBase criteria)
                        //Enforce the authorization policy by modifying the search criteria object being trasferred through adding the store IDs received from the role scopes
                        criteria.StoreIds = allowedStoreIds;                       

In this implementation, we load all StoreSelectedScope objects assigned to the order:read permission in the role definition, and then use the store identifiers retrieved from these scopes to change CustomerOrderSearchCriteria for enforcing the policy to return only orders for the stores defined in the permission scopes.

Check Scope-based Permissions

Since Virto security is based on the default ASP.NET Core security mechanics, we can use IAuthorizationService and custom authorization policy handlers for any imperative authorization check.

        public async Task<ActionResult<CustomerOrder>> GetById(string id, [FromRoute] string respGroup = null)
            var searchCriteria = new CustomerOrderSearchCriteria
                Ids = new[] { id },
                ResponseGroup = respGroup
            //in this line, we use IAuthorizationService _authorizationService to check the 'order:read' permission for the specific resource, CustomerOrderSearchCriteria, where the policy handler can modify the provided criteria and remove or add the stores the user has access to.
            var authorizationResult = await _authorizationService.AuthorizeAsync(User, searchCriteria, new OrderAuthorizationRequirement("order:read"));
            if (!authorizationResult.Succeeded)
                return Unauthorized();
            var result = await _searchService.SearchCustomerOrdersAsync(searchCriteria);

            return Ok(result.Results.FirstOrDefault());

In this example, CustomerOrderSearchCriteria to be secured with AuthorizeAsync overload is invoked to determine whether the current user is allowed to query the orders by the provided search criteria. AuthorizeAsync gets the following tree parameters:

  • User: Currently authenticated user with claims.
  • Criteria: Object that is secured and probably changed inside the authorization handler in accordance with the user restrictions.
  • The new instance of the OrderAuthorizationRequirement type with the permission that needs to be checked.

As a result, the authorization handler will check and change the criteria to return only the orders with the stores the current users can view.