I have an Azure Web App that authenticates a user which then navigates to a page where some Sharepoint documents are retrieved and displayed in the app.
Most of the time the application works fine, but ocassionally App Insights will highlight that Failed to acquire token silently as no token was found in the cache. Call method AcquireToken. Some users report issues from time to time on this page (it's inconsistent so it might happen a few times a day with a somewhat large user base). The problem is that currently the error isn't handled and I'm trying to figure out how to make the call to AcquireTokenAsync.
The following is the method that returns the token (or doesnt):
private async Task<string> GetUserAccessToken()
{
try
{
// Credentials for app
// _clientId and _clientSecret represent the app info - not shown here in code
ClientCredential credential = new ClientCredential(_clientId, _clientSecret);
//Construct token cache
ITokenCacheFactory cacheFactory = Request.HttpContext.RequestServices.GetRequiredService<ITokenCacheFactory>();
TokenCache cache = cacheFactory.CreateForUser(Request.HttpContext.User);
AuthenticationContext authContext = new AuthenticationContext(_authority, cache);
// guid of the user currently logged into the app
string objectID = _userObjectId;
UserIdentifier userIdentifier = new UserIdentifier(objectID, UserIdentifierType.UniqueId);
string resource = "https://test.sharepoint.com";
AuthenticationResult result = await authContext.AcquireTokenSilentAsync(resource, credential, userIdentifier);
return result.AccessToken;
}
catch (Exception ex)
{
throw ex;
}
}
If I understand the flow correctly, the web app here will request a token using it's own credentials on behalf of the user currently logged in. (Am I right in understanding this based on the method signature which states - Identifier of the user token is requested for. This parameter can be Microsoft.IdentityModel.Clients.ActiveDirectory.UserIdentifier.Any.)
Now when this fails, I would need to make a call to AcquireTokenAsync. There are a number of these methods available and I can't seem to find the one that will fulfill this requirement.
Before the suggestion comes, I can't use AcquireTokenAsync(resource, clientId, redirectUri,new PlatformParameters(PromptBehavior.Auto)); because the constructor on PlatformParameters has changed and requires an implementation of a ICustomWebUi and this flow isn't supported on .Net Core 3.1 as far as I'm aware which makes this unusable.
AcquireTokenAsync(resource, credentials) works and returns a token, however, when using that token I get a 401 Unauthorized when accessing the Sharepoint resources, most likely because the token is different and it is now requested on behalf of the application and not the user logged into the application (if I'm following this train of thought correctly...).
My question is - which method do I call? Is there something I would need to add before making the call to AcquireTokenAsync and if so, which of the 10 or so overloads should I use? I tried using AcquireTokenAsync(resource, credenetial, userAssertion) and passed in the AccessToken that I retrieved on the User logged in, but then I got Assertion failed signature validation or variations on that. If I understood correctly, the UserAssertion can be initialized with 1,2 or 3 parameters and I tried providing the AccessToken currently on the user that is logged in the app, but with no success.
Any help is greatly appreciated as I've been looking at this for two days now.
I spent more time investigating this, but none of the methods available would have worked in my case. The auth flow wasn't an on-behalf-of flow, but an auth-code flow. The link is to the newer MSAL library, but the concept is there. The application, a .net core web app, directs the user to sign in. When they sign in, an auth-code is passed into the response once they successfully authenticate.
The auth-code is then used to call AcquireTokenByAuthorizationCodeAsync(AuthCode, Uri, ClientCredential, UserIdentifier). This returns the valid access token that can be stored in the distributed token cache and then used to authenticate in order to access a given resource.
My biggest issue was that the error says you need to use AcquireTokenAsync to retrieve a new token. This is correct to a certain point, because in order to make any calls to any of the 14 or so methods you will need different bits of information, which will be dependent on the way you have setup your authentication flow in your application.
Because the application I worked on used auth code flow, I would need to get a new auth code. This would mean redirecting the user to login, capture the auth code in the response if the login was successful and then call the appropriate AcquireTokenAsync method that takes in an auth code as parameter along with app info, uri and so on.
To solve this, I used the information provided by the Microsoft Github page on Acquiring tokens with auth codes in web apps. Here I found samples on how auth flow is setup, but most importantly, how to trigger a new authentication flow if the user needs to be re-authenticated.
I wrapped the code that would throw the AdalSilentTokenAcquisitionException, catch the error and return a RedirectToAction.
return RedirectToAction("ActionName", "Controller", new RouteValues);
The above redirects the user to a given action, in a particular controller and passes through an object that can hold additional parameters. In my case it's a new { redirectUri = redirectUriString}, which is a string object that holds the URL the user would try to navigate this. I constructed this with a little method that uses the current HttpRequest to find the url the user was trying to get to.
Next, the controller that I had setup which responds to that redirect:
[HttpGet("/SignIn")]
public IActionResult SignIn([FromQuery(Name ="redirectUri")]string redirectUri)
{
return Challenge
(
new AuthenticationProperties { RedirectUri = WebUtility.UrlDecode(redirectUri) },
OpenIdConnectDefaults.AuthenticationScheme
);
}
Here, a Challenge is returned. The challenge triggers a call to the authentication flow that was setup in the Startup class. I think the entire flow here is that the method will send people to go through whatever is in that startup, which, in the case of the application I worked on, it prompts the user to sign in, captures the auth code, requests a new access token and once this is received and saved in the distributed token cache, the user is redirected to the redirectUri that I passed through.
I hope this helps or at least gives a starting point to anyone who might encounter a similar issue.
Related
I'm trying to secure my firebase functions by using authorization.
I wrote a very simple callable function
exports.hey= functions.https.onCall((data, context) => {
return {hello:"world"};
});
then i deployed to GC and add the permission invoker to allAuthenticatedUsers .
then i went to my app and wrote some test code
FirebaseFunctions.getInstance().getHttpsCallable("hey").call(null).addOnCompleteListener(task -> {
if (task.isSuccessful())
System.out.println(task.getResult().getData());
else
FirebaseCrashlytics.getInstance().recordException(task.getException());
});
This code runs after user authenticateFirebaseAuth.getInstance().signInWithCustomToken(); (I've my own authentication system it works I can see the authenticated user in firebase auth dashboard along with last login the user is able to read database) but the function call always returns http 403
I know that within the function i can use the context to check the auth field and verify if user is authenticated, but what is the point of the permissioning system at all in the GC? if at the end we always need to check the context.auth am i missing something?
W/System.err: com.google.firebase.functions.FirebaseFunctionsException: UNAUTHENTICATED
If the ID token passed to a Cloud Function represents a Google account it works, otherwise, it doesn't.
An authenticated client request for a Google Cloud Functions must have an Authorization: Bearer ID_TOKEN header or ?access_token=ID_TOKEN.
The Authentication header is set with the user’s ID token which is used as a context parameter. A Firebase user’s ID token doesn’t always represent a Google user which makes it incompatible with allAuthenticatedUsers. Because of this you check context.auth. Otherwise you may try with “allUsers” which should work.
You can see this stackoverflow answer for more information.
I am sure someone out there has already done this, but I have yet to find any documentation with regard to the Microsoft implementation of JWT. The official documentation from Microsoft for their JWT library is basically an empty page, see:
https://learn.microsoft.com/en-us/dotnet/framework/security/json-web-token-handler-api-reference
So, here is what I (and I am sure many others) would like to accomplish:
Definition: User ID = The username or email address used to log into a system.
AUTHENTICATION:
A user logs in. The user fills in web form and the system sends (via HTTPS POST) the users ID and password (hashed) to the server in order to authenticate / validate the user.
Server Authenticates user. The users ID and password are checked against the values saved in the database and if NOT valid, an invalid login response is returned to the caller.
Create a JWT Token - ???? No documentation available!
Return the JWT token to the caller - ???? - I assume in a header? via JSON, not sure -- again - no documentation.
Given the code below, can anyone provide a code example for steps 3 and 4?
[FunctionName( "authenticate" )]
public static async Task<HttpResponseMessage> Run( [HttpTrigger( AuthorizationLevel.Anonymous, "get", "post", Route = null )]HttpRequestMessage req, TraceWriter log )
{
// Step 1 - Get user ID and password from POST data
/*
* Step 2 - Verify user ID and password (compare against DB values)
* If user ID or password is not valid, return Invalid User response
*/
// Step 3 - Create JWT token - ????
// Step 4 - Return JWT token - ????
}
AUTHORIZATION:
Assuming the user was authenticated and now has a JWT token (I am assuming the JWT token is saved in the users session; if someone wants to provide more info, please do):
A POST request is made to an Azure Function to do something (like get a users birth date). The JWT token obtained above is loaded (from the POST data or a header - does it matter?) along with any other data required by the function.
The JWT token is validated - ???? No documentation available!
If the JWT token is NOT valid, a BadRequest response is returned by the function.
If the JWT token is valid, the function uses the data passed to it to process and issue a response.
Given the code below, can anyone provide a code example for steps 1 and 2?
[FunctionName( "do_something" )]
public static async Task<HttpResponseMessage> Run( [HttpTrigger( AuthorizationLevel.Anonymous, "get", "post", Route = null )]HttpRequestMessage req, TraceWriter log )
{
// Step 1 - Get JWT token (from POST data or headers?)
// Step 2 - Validate the JWT token - ???
// Step 3 - If JWT token is not valid, return BadRequest response
// Step 4 - Process the request and return data as JSON
}
Any and all information would really help those of us (me) understand how to use JWT with Azure (anonymous) functions in order to build a "secure" REST API.
Thanks in advance.
Any and all information would really help those of us (me) understand how to use JWT with Azure (anonymous) functions in order to build a "secure" REST API.
Per my understanding, you could use the related library in your azure function code to generate / validate the JWT token. Here are some tutorials, you could refer to them:
Create and Consume JWT Tokens in C#.
Jwt.Net, a JWT (JSON Web Token) implementation for .NET
JWT Authentication for Asp.Net Web Api
Moreover, you could leverage App Service Authentication / Authorization to configure the function app level Authentication / Authorization. You could go to your Function App Settings, click "NETWORKING > Authentication / Authorization" under the Platform features tab. Enable App Service Authentication and choose Allow Anonymous requests (no action) as follows:
You could create a HttpTrigger function with anonymous accessing for user logging and return the JWT token if the user exists. For the protected REST APIs, you could follow the code sample below:
if(System.Security.Claims.ClaimsPrincipal.Current.Identity.IsAuthenticated)
{
//TODO: retrieve the username claim
return req.CreateResponse(HttpStatusCode.OK,(System.Security.Claims.ClaimsPrincipal.Current.Identity as ClaimsIdentity).Claims.Select(c => new { key = c.Type, value = c.Value }),"application/json");
}
else
{
return req.CreateResponse(HttpStatusCode.Unauthorized,"Access Denied!");
}
For generating the JWT token used in App Service Authentication, you could follow How to: Use custom authentication for your application and the code under custom API controller CustomAuthController from adrian hall's book about Custom Authentication to create the JWT token.
UPDATE:
For the custom authentication approach under App Service Authentication, I just want op to leverage the authentication / Authorization provided by EasyAuth. I have did some test for this approach and found it could work on my side. Op could send the username and password to the HttpTrigger for authentication, then the HttpTrigger backend need to validate the user info, and use Microsoft.Azure.Mobile.Server.Login package for issuing App Service Authentication token to the client, then the client could retrieve the token from the AuthenticationToken property. The subsequent requests against the protected APIs could look like as follows:
https://<your-funapp-name>.azurewebsites.net/api/<httpTrigger-functionName>
Header: x-zumo-auth:<AuthenticationToken>
NOTE:
For this approach, the related HttpTrigger functions need to allow anonymous accessing and the App Service Authentication also needs to choose Allow Anonymous requests (no action). Otherwise, the App Service Authentication and function level authentication would both validate the request. For the protected APIs, op needs to manually add the System.Security.Claims.ClaimsPrincipal.Current.Identity.IsAuthenticated checking.
Try this: https://liftcodeplay.com/2017/11/25/validating-auth0-jwt-tokens-in-azure-functions-aka-how-to-use-auth0-with-azure-functions/
I successfully made it work using this guide. It took awhile due to nuget versions.
Follow that guide properly and use the following nuget versions
IdentityModel.Protocols (2.1.4)
IdentityModel.Protocols.OpenIdConenct (2.1.4)
IdentityModel.Tokens.Jwt (5.1.4)
Oh and, the guide tells you to write your AUDIENCE as your api link, don't. You'll get unauthorized error. Just write the name of your api, e.g. myapi
If you get error about System.http.formatting not being loaded when running the function, try to reinstall NET.Sdk.Functions and ignore the warning about AspNet.WebApi.Client being restored using .NETFramework. And restart visual studio.
What you're describing is something that you should be able to do yourself by doing a little bit of research. To address your specific questions:
Create a JWT Token - ???? No documentation available!
The link Bruce gave you gives a nice example for how to create a JWT: https://www.codeproject.com/Tips/1208535/Create-And-Consume-JWT-Tokens-in-csharp
Return the JWT token to the caller - ???? - I assume in a header? via JSON, not sure -- again - no documentation.
There's no documentation because you're basically inventing your own protocol. That means how you do it is entirely up to you and your application requirements. If it's a login action, it might make sense to return it as part of the HTTP response payload. Just make sure that you're using HTTPS so that the token stays protected over the wire.
A POST request is made to an Azure Function to do something (like get a users birth date). The JWT token obtained above is loaded (from the POST data or a header - does it matter?) along with any other data required by the function.
How you send the token is, again, entirely up to you. Most platforms use the HTTP Authorization request header, but you don't have to if you don't want to.
The JWT token is validated - ???? No documentation available!
Use the ValidateToken method of the JwtSecurityTokenHandler (see the previous link for how to get the JwtSecurityTokenHandler). Docs here: https://msdn.microsoft.com/en-us/library/dn451155(v=vs.114).aspx.
I created an Azure Functions input binding for JWT Token Validation. You can use this as an extra parameter with the [JwtBinding] attribute. See https://hexmaster.nl/posts/az-func-jwt-validator-binding/ for source and NuGet package information.
Basically Azure Functions built on top of ASP.NET Core. By making some dependency injection tricks you could add your own authentication and policy-based authorization. I created demo solution with JWT authentication just for fun, beware to use it on production.
We are building a solution that will need to access our customers Gmail accounts to read/send mail. On account signup, we'd have a pop-up for our customer to do Gmail auth page and then a backend process to periodically read their emails.
The documentation doesn't seem to cover this use case. For example https://developers.google.com/api-client-library/dotnet/guide/aaa_oauth says that client tokens should be stored in client_secrets.json - what if we have 1000s of clients, what then?
Service accounts are for non-user info, but rather application data. Also, if I use the GoogleWebAuthorizationBroker and the user has deleted access or the tokens have expired, I don't want my backend server app to pop open a web brower, as this seems to do.
I would imagine I could use IMAP/SMTP accomplish this, but I don't think it's a good idea to store those credentials in my db, nor do I think Google wants this either.
Is there a reference on how this can be accomplished?
I have this same situation. We are planning a feature where the user is approving access to send email on their behalf, but the actual sending of the messages is executed by a non-interactive process (scheduled task running on an application server).
I think the ultimate answer is a customized IAuthorizationCodeFlow that only supports access with an existing token, and will not execute the authorization process. I would probably have the flow simulate the response that occurs when a user clicks the Deny button on an interactive flow. That is, any need to get an authorization token will simply return a "denied" AuthorizationResult.
My project is still in the R&D phase, and I am not even doing a proof of concept yet. I am offering this answer in the hope that it helps somebody else develop a concrete solution.
While #hurcane's answer more than likely is correct (haven't tried it out), this is what I got working over the past few days. I really didn't want to have to de/serialize data from the file to get this working, so I kinda mashed up this solution
Web app to get customer approval
Using AuthorizationCodeMvcApp from Google.Apis.Auth.OAuth2.Mvc and documentation
Store resulting access & refresh tokens in DB
Use AE.Net.Mail to do initial IMAP access with access token
Backend also uses AE.Net.Mail to access
If token has expired, then use refresh token to get new access token.
I've not done the sending part, but I presume SMTP will work similarly.
The code is based on SO & blog posts:
t = EF object containing token info
ic = new ImapClient("imap.gmail.com", t.EmailAddress, t.AccessToken, AuthMethods.SaslOAuth, 993, true);
To get an updated Access token (needs error handling) (uses the same API as step #1 above)
using (var wb = new WebClient())
{
var data = new NameValueCollection();
data["refresh_token"] = refresh;
data["client_id"] = "(Web app OAuth id)";
data["client_secret"] = "(Web app OAuth secret)";
data["grant_type"] = "refresh_token";
var response = wb.UploadValues(#"https://accounts.google.com/o/oauth2/token", "POST", data);
string Tokens = System.Text.Encoding.UTF8.GetString(response);
var token = Newtonsoft.Json.JsonConvert.DeserializeObject<dynamic>(Tokens);
at = token.access_token;
return at;
}
I used the my Azure Active Directory to protect my web API and I create a native application in the Azure management portal. This native application is basically a MVC web application and I use the ADAL library to get the token and call the api with that token. The code I used to get the token is shown below:
AuthenticationContext ac = new AuthenticationContext(authority);
AuthenticationResult ar = ac.AcquireToken(resourceID, clientID, redirectURI);
string accessToken = ar.AccessToken;
Now I need to logout and switch to another user but somehow the user credentials are remembered by the system. I clear the token cache in the authentication context and post logout api request as follows where *** is my tenant ID.
//Log out after api call
ac.TokenCache.Clear();
string requestUrl = "https://login.windows.net/***/oauth2/logout";
var client = new HttpClient();
var request = new HttpRequestMessage(HttpMethod.Get, requestUrl);
var response = await client.SendAsync(request);
The api call succeeds but the logout doesn't work.
What should I do to logout and switch to another user?
I don't think this would work. You would need to redirect the user to logout URL for logout to work.
Here's how you can create a logout URI:
https://login.microsoftonline.com/{0}/oauth2/logout?post_logout_redirect_uri={1}
Where:
{0} - Fully qualified name of your Azure Active Directory e.g. yourad.onmicrosoft.com or tenant id.
{1} - The URL of your application where a user must be redirected back after the logout is complete. This should be properly URL encoded.
If you goal is to sign in a s a different user, you don't strictly need to log out the first user from its session with Azure AD. You can pass PrompBehavior.Always in your AcquireToken call, so that you will be guaranteed to prompt the user with a clean credential gathering UX.
Note: if you want to wipe every trace of the first user from the app you can keep the cache cleanup code you have. ADAL allows you to keep tokens for multiple users tho, hence if your app as multi-user functions this might be useful - the catch is that if you do so, at every AcquireToken you'll have to also specify which user you want a token for or ADAL won't know which one to return. If you don't need multiple users at once, the cache cleanup + PromptBehavior.Always remains the easiest path.
You can do this for clear cache :
CookieManager cookieManager = CookieManager.getInstance();
cookieManager.removeAllCookie();
CookieSyncManager.getInstance().sync();
mAuthContext.getCache().removeAll();
I'm playing with Azure AD authentication and authorization scenarios and not all clear for me.
Currently I'm looking at SinglePageApp-WebAPI-AngularJS-DotNet sample project.
And one thing that I can't understand. On the client side we get access token using implicit grant flow - that is clear. Then we send request to WEB API with Bearer and access token as value. On the server side we have TodoListController with Authorize attribute. So, in order to hit the controller request must be authorized.
What is not clear how authentication middleware validates my access token (what if random text sent instead of valid access token?). I cloned katana project and investigated WindowsAzureActiveDirectoryBearerAuthenticationExtensions and OAuthBearerAuthenticationHandler classes, but I still can't find concrete place where validation occur.
How my WEB API will know that this particular access token is valid and where is this concrete line of code, which is responsible for validation?
Thanks!
UPD:
Actually I find the place. All work is done inside OAuthBearerAuthenticationHandler in method AuthenticateCoreAsync:
tokenReceiveContext.DeserializeTicket(tokenReceiveContext.Token);
this call leads to running JwtFormat.Unprotect method, which performs actual validation.
Thanks #Aram for good notes.
In your service start up you register OWIN and when your controller is decorated with Authorize attribute then the authentication challenge will happen and OWIN will try to validate the token on each request..
The token validation happens because you have OWIN Dll references AND you have the startup.auth class in your service project...
You probably have something like this, that you include Auth challenge in the service side:
app.UseWindowsAzureActiveDirectoryBearerAuthentication(
new WindowsAzureActiveDirectoryBearerAuthenticationOptions
{
Audience = ConfigurationManager.AppSettings["ida:Audience"],
Tenant = ConfigurationManager.AppSettings["ida:Tenant"],
});
When the validation is happening, the OWIN middleware will validate against the Audience and the Tenant that the token has been acquired from, and if they dont match the Authz will fail...
Depending on with Authentication handler you use the actual code that calls the ValidateToken function is in YOUR_AUTH_HANDLERAuthenticationHandler class.
Here is the location for OpenId AuthZ handler:
http://katanaproject.codeplex.com/sourcecontrol/latest#src/Microsoft.Owin.Security.OpenIdConnect/OpenidConnectAuthenticationHandler.cs
For instance if you have OpenIdConnect Authz handler then the token validation is in : Microsoft.Owin.Security.OpenIdConnect.OpenIdConnectAuthenticationHandler class and the Overrride method :
protected override async Task<AuthenticationTicket> AuthenticateCoreAsync()
And the ValidateToekn code will look like (if your AuthZ handler is OpenId connect):
ClaimsPrincipal principal = Options.SecurityTokenHandlers.ValidateToken(openIdConnectMessage.IdToken, tvp, out validatedToken);