I want to be able to globally access the logged-in user in (Controllers, HtmlHelpers and other helper classes) throughout the whole application without getting exceptions that User is null and with the ability to handle guests (not-logged-in users).
Should this be handled within my UsersRepository? If so, how to? or is there a better approach?
You can create custom identity and principal classes. Your custom identity class can extend whatever you are currently using and can then simply add the extra information you need.
Then in a global action filter, simply overwrite the current principal with your customized one. Then you can access it from anywhere like a normal identity, but if you need your additional information, you simply cast it to your custom identity class. Which will grant you access to your additional information.
You can write a custom action filter that is executed on every request (you register it as a global filter). This filter would load the user (from the user´s repository for example) and put it the http context for example or in the ViewData.
EDIT:
Ok, the code for the filter could look like this (in this case, it loads the user to the ViewData collection). I didn´t consider anonymous users here.
public class LoadUserToViewDataAttribute : ActionFilterAttribute
{
private IUserRepository _userRepository;
public LoadUserToViewDataAttribute(IUserRepository userRepository)
{
_userRepository = userRepository;
}
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
var controller = filterContext.Controller;
var userName = filterContext.HttpContext.User.Identity.Name;
var user = _repository.GetUser(userName);
controller.ViewData.Add("CurrentUser", user);
}
}
I have an asp.net mvc app which has membership implemented.
So a user has to log in. Each user belongs to a organisation (multi-tenancy).
How would I handle the organisation parameter globaly? I was thinking this could be a good thing for a global filter because all the data needs to be filtered for the given organisation. And the organisation is connected with the username but not in the same table.
for example I have a index action like this
public ActionResult Index()
{
var result = _repository.GetListByOrganisation(organisation);
return View(result);
}
I was thinking about having a global attribute thats queries the db for an organisation based on a giving username. Since my controller already contains the authorize attribute I have the user name. It would be nice to cache the organisation (session, controllercontext) and not query the organisation from db on each request.
Is this a way to implement something like this? Or are there other ways which would be better? And how can I set a property on the controller / controllercontext from whithin a filter?
So any thoughts on this as well as comments would be great...
I would do this via DI.
You can use either a third-party DI container or your own code. Either way, you want to set the organization ID on a per-request basis.
So you'll be creating a unit of work and injecting that in your controller. For the sake of simplicity, let's pretend that your unit of work is the _repository field in your sample code, even though most real-world apps are more complex.
You add a constructor parameter to the controller:
public FooController(IFooRepository repository)
{
this._repository = repository;
}
...and an organization ID on FooRepository:
public class FooRepository: IFooRepository
{
public FooRepository(long organizationId)
{
this._organizationId = organizationId;
}
}
Now in either your DI container setup or a MVC controller factory, you set this all up:
builder.Register(c => new FooRepository(GetOrgIdForCurrentUser()).As<IFooRepository>();
builder.Register(c => new FooController(c.Resolve<IFooRepository>());
Perhaps you could have the organization embedded on the URL, for example if your route looks like this /{organization}/{controller}/{action}
then you'll get URLs like
/bigorg/products/list
/smallorg/products/list
and you'll receive the organization in your controller either a parameter to your method or via the RouteData object.
I am wondering how to ensure that an employee cannot access information from another company). This is not an authentication / roles based question on applying roles or permissions to actions, but rather ensuring that the data somebody is try to access actually belongs to them.
Users belong to a department which in turn belongs to a company. In the below example the calendar belongs to a company. How do I ensure that the user can only edit calendars within their own company.
public ActionResult Edit(int? calendarId)
{
...
}
So when a user browses to /Calendars/55 how do I ensure that the calendar belongs to the same company as the user? So that for example, you can't tamper with the URL and put in an id for a calendar that belongs to another company.
Approach 1
public ActionResult Edit(int? calendarId)
{
// get company that calendar belongs to
int calCompanyId = ..
if (CurrentUser.CompanyId != calCompanyId)
return RedirectToAction(....); // cannot access resource
...
}
Whilst this would work, I'm wondering if there is a better way to handle this sort of problem. Possibly that wouldn't require putting in checks for every single action across all controllers like this.
Is there a typical pattern used to solve a problem like this where you need to check the user has access to the particular route? I would think this is a pretty typical problem for applications that have resources(companies, departments etc.) and need to ensure one company/user cannot access another companies data.
Edit:
As pointed out by #jfar, I could use the CompanyId but it's not available in most routes. Should I consider changing my route structure to always include this to make these checks easier? Doing this would be a fair amount of work and would probably 'uglify' the routes though.
Upon thinking about this problem further I think there may be no other choice then to put something similar to an 'IsOwner(....)' check within most actions. The reason for this is a couple fold;
Not all items accessible by a route have a CompanyId property on them that can be easily compared to against the user's companyId for example
A resource in a route might have a departmentId which is in turned owned by a company. So in this scenario I would have to implement an overloaded 'IsOwner' that knows to check a departmentId or follow the reference up to the company that owns the department
At this stage I thinking along the lines that I will have an 'IsOwner' method simlar to what #jfar posted that can check if a resource that is directly linked to a company is owned by that company, whilst providing some overloaded versions.
CompanyOwns(CurrentUser.CompanyId, model);
DepartmentOwns(CurrentUser.departmentId, model);
All my database models implement an interface that makes finding them by id easier.
public interface IAmIdentifiable<T>
{
T Id { get; }
}
I might think about adding some more interfaces to the model to aid in the aforementioned helper process like
public interface IAmOwnedByACompany
{
int CompanyId { get; }
}
public interface IAmOwnedByADepartment
{
int DepartmentId { get; }
}
This will make checking objects in 'IsOwner' type methods via reflection easier. I haven't had time to completely think this through but believe #jfar was right when he said in this sort of scenario, you really do have to some form of manual checking in each method when determine whether a user should have access to a particular route (which represents a resource). By implementing some interfaces and some clever 'IsOwner' type methods, I hope to make these checks quite simple.
You could add this into your base controller. Every request, if an RouteParameter named {CompanyId} comes in, automatically check to make sure the CurrentUser.CompanyId matches it.
protected User CurrentUser { get; set; }
protected override void OnAuthorization(AuthorizationContext filterContext)
{
base.OnAuthorization(filterContext);
if( RouteData.Values["CompanyId"] != null )
if (CurrentUser.CompanyId != RouteData.Values["CompanyId"] )
//Redirect to wherever
//your not restricted from getting the companyid from the route
//you could get the id from the logged in user, session, or any other method
}
Update:
You could create a helper that uses reflection to check if entities have the right owner. Code written on the fly, could have an error.
public bool IsOwner<T>(T model, int companyId)
{
var prop = model.GetType().GetProperty("CompanyId");
if (prop == null)
return false;
var modelCompanyId = (int)prop.GetValue(model, null);
return modelCompanyId == companyId;
}
Given an ASP.NET MVC Controller class declaration:
public class ItemController : Controller
{
public ActionResult Index()
{
// ...
}
public ActionResult Details()
{
// ...
}
[Authorize(Roles="Admin, Editor")]
public ActionResult Edit()
{
// ...
}
[Authorize(Roles="Admin")]
public ActionResult Delete()
{
// ..
}
}
I need to reflect a list of methods in this class which may be invoked with the current user's permissions.
Please share some ideas of what could be done in this case.
Well for the new question think something along the lines of:
new ReflectedControllerDescriptor(typeof(ItemController)).GetCanonicalActions()
could be used to return the list of all available actions. I don't have ASP.NET MVC available to me at work, so I can't really check to see if the ActionDescriptor's returned by that will contain some parameter which says which members are allowed to execute them.
http://msdn.microsoft.com/en-us/library/system.web.mvc.actiondescriptor_members%28v=VS.90%29.aspx
That is the members of the ActionDescriptor, you might be able to find something in there. I'll see tonight if I can figure it out, this has gotten me kind of intrigued.
There's no universal user login/authentication system for all applications, thus this really isn't possible to create a 'universal solution'. You could create your own user login and authorization classes which you then add your own annotations to methods to do, but its going to have the same restrictions that the asp.net mvc system has, its only for your login/authorization system (or whoever extends that system).
Preamble: this is a bit of a philosophical question. I'm looking more for the "right" way to do this rather than "a" way to do this.
Let's imagine I have some products, and an ASP.NET MVC application performing CRUD on those products:-
mysite.example/products/1
mysite.example/products/1/edit
I'm using the repository pattern, so it doesn't matter where these products come from:-
public interface IProductRepository
{
IEnumberable<Product> GetProducts();
....
}
Also my Repository describes a list of Users, and which products they are managers for (many-many between Users and Products). Elsewhere in the application, a Super-Admin is performing CRUD on Users and managing the relationship between Users and the Products they are permitted to manage.
Anyone is allowed to view any product, but only users who are designated as "admins" for a particular product are allowed to invoke e.g. the Edit action.
How should I go about implementing that in ASP.NET MVC? Unless I've missed something, I can't use the built-in ASP.NET Authorize attribute as first I'd need a different role for every product, and second I won't know which role to check for until I've retrieved my Product from the Repository.
Obviously you can generalise from this scenario to most content-management scenarios - e.g. Users are only allowed to edit their own Forum Posts. StackOverflow users are only allowed to edit their own questions - unless they've got 2000 or more rep...
The simplest solution, as an example, would be something like:-
public class ProductsController
{
public ActionResult Edit(int id)
{
Product p = ProductRepository.GetProductById(id);
User u = UserService.GetUser(); // Gets the currently logged in user
if (ProductAdminService.UserIsAdminForProduct(u, p))
{
return View(p);
}
else
{
return RedirectToAction("AccessDenied");
}
}
}
My issues:
Some of this code will need to be repeated - imagine there are several operations (Update, Delete, SetStock, Order, CreateOffer) depending on the User-Products relationship. You'd have to copy-paste several times.
It's not very testable - you've got to mock up by my count four objects for every test.
It doesn't really seem like the controller's "job" to be checking whether the user is allowed to perform the action. I'd much rather a more pluggable (e.g. AOP via attributes) solution. However, would that necessarily mean you'd have to SELECT the product twice (once in the AuthorizationFilter, and again in the Controller)?
Would it be better to return a 403 if the user isn't allowed to make this request? If so, how would I go about doing that?
I'll probably keep this updated as I get ideas myself, but I'm very eager to hear yours!
Thanks in advance!
Edit
Just to add a bit of detail here. The issue I'm having is that I want the business rule "Only users with permission may edit products" to be contained in one and only one place. I feel that the same code which determines whether a user can GET or POST to the Edit action should also be responsible for determining whether to render the "Edit" link on the Index or Details views. Maybe that's not possible/not feasible, but I feel like it should be...
Edit 2
Starting a bounty on this one. I've received some good and helpful answers, but nothing that I feel comfortable "accepting". Bear in mind that I'm looking for a nice clean method to keep the business logic that determines whether or not the "Edit" link on the index view will be displayed in the same place that determines whether or not a request to Products/Edit/1 is authorised or not. I'd like to keep the pollution in my action method to an absolute minimum. Ideally, I'm looking for an attribute-based solution, but I accept that may be impossible.
First of all, I think you already half-way figured it, becuase you stated that
as first I'd need a different role for every product, and second I won't know which role to check for until I've retrieved my Product from the Repository
I've seen so many attempts at making role-based security do something it was never intended to do, but you are already past that point, so that's cool :)
The alternative to role-based security is ACL-based security, and I think that is what you need here.
You will still need to retrieve the ACL for a product and then check if the user has the right permission for the product. This is so context-sensitive and interaction-heavy that I think that a purely declarative approach is both too inflexible and too implicit (i.e. you may not realize how many database reads are involved in adding a single attribute to some code).
I think scenarios like this are best modeled by a class that encapsulates the ACL logic, allowing you to either Query for decision or making an Assertion based on the current context - something like this:
var p = this.ProductRepository.GetProductById(id);
var user = this.GetUser();
var permission = new ProductEditPermission(p);
If you just want to know whether the user can edit the product, you can issue a Query:
bool canEdit = permission.IsGrantedTo(user);
If you just want to ensure that the user has rights to continue, you can issue an Assertion:
permission.Demand(user);
This should then throw an exception if the permission is not granted.
This all assumes that the Product class (the variable p) has an associated ACL, like this:
public class Product
{
public IEnumerable<ProductAccessRule> AccessRules { get; }
// other members...
}
You might want to take a look at System.Security.AccessControl.FileSystemSecurity for inspiration about modeling ACLs.
If the current user is the same as Thread.CurrentPrincipal (which is the case in ASP.NET MVC, IIRC), you can simplyfy the above permission methods to:
bool canEdit = permission.IsGranted();
or
permission.Demand();
because the user would be implicit. You can take a look at System.Security.Permissions.PrincipalPermission for inspiration.
From what you are describing it sounds like you need some form of user access control rather than role based permissions. If this is the case then it needs to be implemented throughout your business logic. Your scenario sounds like you can implement it in your service layer.
Basically you have to implement all functions in your ProductRepository from the perspective of the current user and the products are tagged with permissions for that user.
It sounds more difficult than it actually is. First off you need a user token interface that contains the user information of uid and role list (if you want to use roles). You can use IPrincipal or create your own along the lines of
public interface IUserToken {
public int Uid { get; }
public bool IsInRole(string role);
}
Then in your controller you parse the user token into your Repository constructor.
IProductRepository ProductRepository = new ProductRepository(User); //using IPrincipal
If you're using FormsAuthentication and a custom IUserToken then you can create a Wrapper around the IPrincipal so your ProductRepository is created like:
IProductRepository ProductRepository = new ProductRepository(new IUserTokenWrapper(User));
Now all your IProductRepository functions should access the user token to check permissions. For example:
public Product GetProductById(productId) {
Product product = InternalGetProductById(UserToken.uid, productId);
if (product == null) {
throw new NotAuthorizedException();
}
product.CanEdit = (
UserToken.IsInRole("admin") || //user is administrator
UserToken.Uid == product.CreatedByID || //user is creator
HasUserPermissionToEdit(UserToken.Uid, productId) //other custom permissions
);
}
If you wondering about getting a list of all products, in your data access code you can query based on permission. In your case a left join to see if the many-to-many table contains the UserToken.Uid and the productId. If the right side of the join is present you know the user has permission to that product and then you can set your Product.CanEdit boolean.
Using this method you can then use the following, if you like, in your View (where Model is your Product).
<% if(Model.CanEdit) { %>
Edit
<% } %>
or in your controller
public ActionResult Get(int id) {
Product p = ProductRepository.GetProductById(id);
if (p.CanEdit) {
return View("EditProduct");
}
else {
return View("Product");
}
}
The benefit to this method is that the security is built in to your service layer (ProductRepository) so it is not handled by your controllers and cannot be bypassed by your controllers.
The main point is that the security is placed in your business logic and not in your controller.
The copy paste solutions really become tedious after a while, and is really annoying to maintain. I would probably go with a custom attribute doing what you need. You can use the excellent .NET Reflector to see how the AuthorizeAttribute is implemented and perform your own logic to it.
What it does is inheriting FilterAttribute and implementing IAuthorizationFilter. I can't test this at the moment, but something like this should work.
[AttributeUsage(AttributeTargets.Method | AttributeTargets.Class, Inherited = true, AllowMultiple = true)]
public class ProductAuthorizeAttribute : FilterAttribute, IAuthorizationFilter
{
public void OnAuthorization(AuthorizationContext filterContext)
{
if (filterContext == null)
{
throw new ArgumentNullException("filterContext");
}
object productId;
if (!filterContext.RouteData.Values.TryGetValue("productId", out productId))
{
filterContext.Result = new HttpUnauthorizedResult();
return;
}
// Fetch product and check for accessrights
if (user.IsAuthorizedFor(productId))
{
HttpCachePolicyBase cache = filterContext.HttpContext.Response.Cache;
cache.SetProxyMaxAge(new TimeSpan(0L));
cache.AddValidationCallback(new HttpCacheValidateHandler(this.Validate), null);
}
else
filterContext.Result = new HttpUnauthorizedResult();
}
private void Validate(HttpContext context, object data, ref HttpValidationStatus validationStatus)
{
// The original attribute performs some validation in here as well, not sure it is needed though
validationStatus = HttpValidationStatus.Valid;
}
}
You could probably also store the product/user that you fetch in the filterContext.Controller.TempData so you can fetch it in the controller, or store it in some cache.
Edit: I just noticed the part about the edit link. The best way I can think of is factoring out the authorization part from the attribute and make a HttpHelper for it that you can use in your view.
I tend to think that authorization is part of your business logic (or at least outside of your controller logic anyway). I agree with kevingessner above, in that the authorization check should be part of the call to fetch the item. In his OnException method, you could show the login page (or whatever you have configured in the web.config) by something like this:
if (...)
{
Response.StatusCode = 401;
Response.StatusDescription = "Unauthorized";
HttpContext.Response.End();
}
And instead of making UserRepository.GetUserSomehowFromTheRequest() calls in all the action methods, I would do this once (in an override of the Controller.OnAuthorization method for example), then stick that data somewhere in your controller base class for later use (e.g. a property).
I think that it's unrealistic, and a violation of the separation of concerns, to expect to have controller/model code control what the view renders. The controller/model code can set a flag, in the view model, that the view can use to determine what it should do, but I don't think that you should expect a single method to be used by both controller/model and view to control both access to and rendering of the model.
Having said that you could approach this in either of two ways -- both would involve a view model that carries some annotations used by the view in addition to the actual model. In the first case, you can use an attribute to control access to the action. This would be my preference, but would involve decorating each method independently -- unless all of the actions in a controller have the same access attributes.
I've developed a "role or owner" attribute for just this purpose. It verifies that the user is in a particular role or is the owner of the data being produced by the method. Ownership, in my case, is controlled by the presence of a foreign key relationship between the user and the data in question -- that is, you have a ProductOwner table and there needs to be a row containing the product/owner pair for the product and current user. It differs from the normal AuthorizeAttribute in that when the ownership or role check fails, the user is directed to an error page, not the login page. In this case, each method would need to set a flag in the view model that indicates that the model can be edited.
Alternatively, you could implement similar code in the ActionExecuting/ActionExecuted methods of the controller (or a base controller so that it applies consistently across all controllers). In this case, you would need to write some code to detect what kind of action is being executed so you know whether to abort the action based on the ownership of the product in question. The same method would set the flag to indicate that the model can be edited. In this case, you'd probably need a model hierarchy so you could cast the model as an editable model so that you can set the property regardless of the specific model type.
This option seems more coupled to me than using the attribute and arguably more complicated. In the case of the attribute you can design it so that it takes the various table and property names as attributes to the attribute and uses reflection to get the proper data from your repository based on the attribute's properties.
Answering my own question (eep!), Chapter 1 of Professional ASP.NET MVC 1.0 (the NerdDinner tutorial) recommends a similar solution to mine above:
public ActionResult Edit(int id)
{
Dinner dinner = dinnerRepositor.GetDinner(id);
if(!dinner.IsHostedBy(User.Identity.Name))
return View("InvalidOwner");
return View(new DinnerFormViewModel(dinner));
}
Asides from making me hungry for my dinner, this doesn't really add anything as the tutorial goes on to repeat the code implementing the business rule immediately in the matching POST Action Method, and in the Details view (actually in a child partial of the Details view)
Does that violate SRP? If the business rule changed (so that e.g. anyone who had RSVP'd could edit the dinner), you'd have to change both GET and POST methods, and the View (and the GET and POST methods and View for the Delete operation too, although that's technically a seperate business rule).
Is pulling the logic out into some kind of permissions arbitrator object (as I've done above) as good as it gets?
You're on the right track, but you can encapsulate all of the permission check into a single method like GetProductForUser, which takes a product, user, and the required permission. By throwing an exception that's caught in the controller's OnException handler, the handling is all in one place:
enum Permission
{
Forbidden = 0,
Access = 1,
Admin = 2
}
public class ProductForbiddenException : Exception
{ }
public class ProductsController
{
public Product GetProductForUser(int id, User u, Permission perm)
{
Product p = ProductRepository.GetProductById(id);
if (ProductPermissionService.UserPermission(u, p) < perm)
{
throw new ProductForbiddenException();
}
return p;
}
public ActionResult Edit(int id)
{
User u = UserRepository.GetUserSomehowFromTheRequest();
Product p = GetProductForUser(id, u, Permission.Admin);
return View(p);
}
public ActionResult View(int id)
{
User u = UserRepository.GetUserSomehowFromTheRequest();
Product p = GetProductForUser(id, u, Permission.Access);
return View(p);
}
public override void OnException(ExceptionContext filterContext)
{
if (typeof(filterContext.Exception) == typeof(ProductForbiddenException))
{
// handle me!
}
base.OnException(filterContext);
}
}
You just have to provide ProductPermissionService.UserPermission, to return a user's permission on a given product.By using a Permission enum (I think I've got the right syntax...) and comparing permissions with <, Admin permissions imply Access permissions, which is pretty much always right.
You can use a XACML based implementation. This way you can externalize authorization and also have a repository for your policies outside of your code.