Geoff's Blog

In my last article we talked about implementing AD single sign-on authentication to an MVC5 website, now we're going to look at adding AD group authorization to a controller with a customised AuthorizeAttribute implementation. Azure AD doesn’t currently allow addition or custom roles, there are a number of built-in administrator roles; however we have full control over groups so we can use these for authorization.

Unfortunately authorization isn’t as simple as just using the Authorize attribute with a role as you would with ASP.Net roles, we need to query the Azure AD Graph API to check if a user is a member of the group. We’ll add a Sales group to the AzureBakery AD we created in the last article and then implement a custom AuthorizeAttribute to query the Azure AD Graph API using the Azure AD Graph client.

This was written for an MVC controller but can be used for a Web API controller and could used with Azure Mobile Services too.

We’re going to use the Azure AD PowerShell module to modify the AD Application service principal later in the procedure, so install this first.

You can download the module from here:

· 32-bit version: http://go.microsoft.com/fwlink/p/?linkid=236298
· 64-bit version: http://go.microsoft.com/fwlink/p/?linkid=236297

I needed to install Microsoft Online Services Sign-In Assistant for IT Professionals BETA (not RTW): http://www.microsoft.com/en-us/download/confirmation.aspx?id=39267

Creating an AD Group

1. First go the AD GROUP workspace in the portal for our Active Directory and click ADD GROUP on the toolbar:

2. Enter a name and description of the group and click the tick button to create it:

3. Next click on the newly created group and then ADD MEMBERS on the toolbar:

4. In the Add members dialog, click on the AD user we created to add it to the SELECTED list and click the tick button to confirm:

5. Now go to the GROUP CONFIGURE tab and make a note of the OBJECT ID, we’ll need this later.

6. Next we need to create a key for our application to allow us to access the graph API, so create a new key in the APPLICATION workspace CONFIGURE tab:

7. Make a note of this and the CLIENT ID.

8. We need to create keys for the local and Azure AD applications.

Modifying the Application Service Principal

We need to modify our application’s Service Principal so that it has permission to access the Graph API, in theory this should be done by adjusting the permissions to other applications section of the APPLICATION CONFIGURATION tab but at the time of writing this it doesn’t work. Please try it yourself and if it doesn’t work for you (you will get an unauthorized exception in the AD Graph API Client) use the following procedure to manually add the service principal to an administrator role:

1. Launch the Azure AD PowerShell Console (from the desktop shortcut if you chose to use it).

2. First we need to obtain our AD credentials, so type the following command and enter your AD user credentials when prompted:

$msolcred = get-credential

This stores the credentials in a variable called $msolcred.

3. Next we need to connect the console by typing the following command:

connect-msolservice -credential $msolcred

For a quick test, we can use the get-msoluser command to list AD users. We should see something like this:

PS C:\WINDOWS\system32> get-msoluser

UserPrincipalName DisplayName isLicensed

----------------- ----------- ----------

gwebbercross_outlook.co... Geoff Webber-Cross False

geoff@azurebakery.onmic... Geoff False

4. Now we need to get the service principal for our application using the following command (get the CLIENT ID from CONFIGURE tab of the AD APPLICATION workspace for the application associated with the website):

$msolServicePrincipal = Get-MsolServicePrincipal -AppPrincipalId YourClientId

5. We can see the properties of the service principal object by outputting it like this:

write-output $msolServicePrincipal

6. Next we need to add the service principal to an administrator role like this:

Add-MsolRoleMember -RoleName “Company Administrator” -RoleMemberObjectId $msolServicePrincipal.ObjectId –RoleMemberType ServicePrincipal

Implementing AzureAdAuthorizeAttribute

We’re going to create a class called AzureAdAuthorizeAttribute which can be added to a controller with either a group name or group ObjectId specified. The ObjectId implementation is more efficient as it doesn’t require an additional query to look up the id from the name.

We need to install the Microsoft.Azure.ActiveDirectory.GraphClient and Microsoft.IdentityModel.Clients.ActiveDirectory Microsoft.IdentityModel.Clients.ActiveDirectory NuGet packages by entering the following commands:

Install-Package Microsoft.Azure.ActiveDirectory.GraphClient
Install-Package Microsoft.IdentityModel.Clients.ActiveDirectory

This is the complete code for the attribute, the comments in the code explain what’s going on:

using Microsoft.Azure.ActiveDirectory.GraphClient;

using Microsoft.IdentityModel.Clients.ActiveDirectory;

using System;

using System.Collections.Generic;

using System.Configuration;

using System.Linq;

using System.Security.Claims;

using System.Web;

using System.Web.Mvc;

namespace AdminWebsite.Auth

{

[AttributeUsageAttribute(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = true)]

public class AzureAdAuthorizeAttribute : AuthorizeAttribute

{

private readonly string _clientId = null;

private readonly string _appKey = null;

private readonly string _graphResourceID = "https://graph.windows.net";

public string AdGroup { get; set; }

public string AdGroupObjectId { get; set; }

public AzureAdAuthorizeAttribute()

{

this._clientId = ConfigurationManager.AppSettings["ida:ClientID"];

this._appKey = ConfigurationManager.AppSettings["ida:Password"];

}

protected override bool AuthorizeCore(HttpContextBase httpContext)

{

// First check if user is authenticated

if (!ClaimsPrincipal.Current.Identity.IsAuthenticated)

return false;

else if (this.AdGroup == null && this.AdGroupObjectId == null) // If there are no groups return here

return base.AuthorizeCore(httpContext);

// Now check if user is in group by querying Azure AD Graph API using client

bool inGroup = false;

try

{

// Get information from user claim

string signedInUserId = ClaimsPrincipal.Current.FindFirst(ClaimTypes.NameIdentifier).Value;

string tenantId = ClaimsPrincipal.Current.FindFirst("http://schemas.microsoft.com/identity/claims/tenantid").Value;

string userObjectId = ClaimsPrincipal.Current.FindFirst("http://schemas.microsoft.com/identity/claims/objectidentifier").Value;

// Get AuthenticationResult for access token

var clientCred = new ClientCredential(_clientId, _appKey);

var authContext = new AuthenticationContext(string.Format("https://login.windows.net/{0}", tenantId));

var authResult = authContext.AcquireToken(_graphResourceID, clientCred);

// Create graph connection with our access token and API version

var currentCallContext = new CallContext(authResult.AccessToken, Guid.NewGuid(), "2013-11-08");

var graphConnection = new GraphConnection(currentCallContext);

// If we don't have a group id, we can quiery the graph API to find it

if (this.AdGroupObjectId == null)

{

// Get all groups

var groups = graphConnection.List<Group>(null, null);

if (groups != null && groups.Results != null)

{

// Find group object

var group = groups.Results.SingleOrDefault(r => (r as Group).DisplayName == this.AdGroup);

// check if user is in group

if (group != null)

this.AdGroupObjectId = group.ObjectId;

}

if (this.AdGroupObjectId != null)

inGroup = graphConnection.IsMemberOf(this.AdGroupObjectId, userObjectId);

}

catch(Exception ex)

{

string message = string.Format("Unable to authorize AD user: {0} against group: {1}", ClaimsPrincipal.Current.Identity.Name, this.AdGroup);

throw new Exception(message, ex);

}

return inGroup;

}

Once we’ve created this class, we need to add the ida:ClientID and ida:Password settings to the web.config like this:

</appSettings>

Once we’ve done this, we can simply add the attribute to our controllers to implement Azure AD Group authorization like this:

namespace AdminWebsite.Controllers

{

[AzureAdAuthorize(AdGroup = "Sales", AdGroupObjectId = "f8a96bf1-c152-41a8-abcdefabcdef")]

public class HomeController : Controller

{

public ActionResult Index()

{

return View();

}

So that we can automatically switch the web.config settings for the Azure web application, we can simply add the following transform to web.Release.config which will be run during publishing:

</appSettings>

<system.web>

Azure Active Directory Single Sign-On can be used with MVC websites to allow us to create websites with single sign-on authentication for Azure AD users which can be centrally managed in Azure AD.

Visual Studio 2013 makes implementing this really easy and we don't need to touch AD Applications, or web.config in our website.

This article is an extract from a new book I'm writing titled "Learning Microsoft Azure" for Packt Publishing. This website is an admin website for the Sales Business domain of a fictional industrial bakery called Azure Bakery.

I this article, we’re going to create an Azure Active Directory for the company, then add a user and configure a new MVC5 Administrator website to implement Azure AD Single Sign-On.

Configuring Active Directory

First we need to create an Active Directory and an initial user account to sign in with

1. From the NEW Services menu, select ACTIVE DIRECTORY | DIRECTORY | CUSTOM CREATE:

2. Fill out the NAME of the directory, it’s DOMAIN NAME and the COUNTRY OR REGION:

3. Now from the Active Directory USERS workspace, click ADD USER from the bottom toolbar to add a user:

4. Fill in the USER NAME. I’ve left TYPE OF USER as New user in your organization, although you can add an existing Microsoft account or Windows Azure AD directory:

5. Next, fill in the user details, select Global Administrator for the ROLE and click the next arrow:

6. Click create on the next tab to get the temporary password for the user. Make a note of it and also enter an email to send it to, then click the tick button to finish:

Configuring an MVC Website for AD Single Sign-On

Next we’ll create a new MVC website and use the wizard to help us setup AD single sign-on. In Visual Studio 2012 this was quite tricky to do with a fair amount of manual configuration in the portal and the website’s web.config, but it’s quite straight forward in Visual Studio 2013.

1. In Visual Studio, add a new ASP.Net Web Application. From the template dialog, select the MVC template, check Create remote resources under the Windows Azure section and then click Change Authentication:

2. Select Organizational Accounts and enter the AD domain name for the Active Directory we just created and click OK:

3. Sign in using the new Active Directory user, then click OK in the previous dialog (be careful to change the user to your Azure portal account when prompted to sign into Azure).

4. Enter the Site name, choose Subscription, Region, Database Server (select No database because we’re using the existing one):

5. Click OK, this will now provision the website, setup an AD application and create our MVC project for us.

6. We can test this locally by simply running the website from Visual Studio. You will get a security warning due to the implementation of a temporary SSL certificate on your local web server like this (in IE):

7. Accept the warning (Continue to this website (not recommended) and you will then see the AD Login page:

8. Login with your new user and the website should load.

Publishing the Website with AD Single Sign-on

When Visual Studio provisioned our website for us it created an application entry in the AD APPLICATIONS tab for our local debug configuration:

Rather than changing the APPLICATION CONFIGURATION for our production website, when we publish the application, there is an option to Enable Organizational Authentication which will add a new application entry in AD and rewrite the federation section of the web.config for us on publish:

<system.identityModel.services>

</federationConfiguration>

</system.identityModel.services>

In the Publish Web dialog, check Enable Organizational Authentication and enter the AD Domain name. You will need to include a connection string for your database as the website will update the database with entries in new IssuingAuthorityKeys and Tenants tables:

Once published, we will see a new entry in the AD APPLICATIONS workspace:

This is great as we don’t need to reconfigure the applications between running locally and publishing to Azure.

Geoff's Blog

Tuesday 29 July 2014

Local Debugging an Azure Mobile Service with AD Auth

Friday 16 May 2014

Moving away from Blogger

Sunday 11 May 2014

Implementing Azure AD Group Authorization