Authentication using Firebase for Flask Application running in appengine - python

Hi I have our website running on appengine with flask as backend framework and we have built our authentication and session management using libraries Flask-OAuth, Flask-Login.
But now I have a requirement to use firebase for authentication.
I am able create sample applications following firebase tutorials but I do no how to integrate with existing application.
In Firenotes samples provided by firebase team they are using two separate services frontend and backend.
I thought of using firebase code in login.html page and once client authenticated pass the info to /profile url -> log the user_id in database and login-user using Flask-Login.
I am not sure whether the above flow is correct and I am not to ensure that it is correct one without any problems in future.
Please help with any ideas as I need to implement it very soon!!

Flask-Login uses session based authentication. Clients login using an authentication scheme. Since you are using Flask-OAuth, it's the oauth flow. If the user successfully authenticates, Flask-Login sends a response during the token exchange step setting an HTTP only cookie (meaning javascript can't access it) with a token unique to the user session. The client then authenticates future requests for the duration of the session with that token. The server can invalidate the session at any time, forcing the client to log in again.
Meanwhile, firebase authentication is JSON Web Token (JWT) authentication scheme. After completing the login flow, the firebase API retrieves a JWT from google's application servers.
To authenticate requests, you need to transmit that JWT on EVERY request. Your server MUST also validate the JWT to ensure that it is both valid and unexpired.
You'll note that the manner by which the JWT arrives at the server is unspecified by the firebase SDK and libraries. I recommend using a Authentication: JWT <google's jwt> header.
One way to resolve your question would be to use the JWT to complete the initial login flow, and then rely on session based auth from there. You'd set up a login endpoint that expects and validates a JWT, and responds with the set cookie header. From that point forward you continue using your flask-login provided session based auth.
Google actually has an example of this in their documentation: https://firebase.google.com/docs/auth/admin/manage-cookies

Related

Microsoft MSAL React SPA, and RESTful Django API

I don't know why I can't find confirmation in the docs, maybe I am not navigating them correctly, although MSAL seems to have options to fit it into any application. This is my first time integrating a SAML sso procedure into any of my web-apps. I am just looking for some clarity on the correct, and secure way to verify the person attempting to login, is actually logged in with the IDP.
I am confused at the part after confirmation of login is given to my redirect API, I currently have it all happening on the front-end, then submitting the response to my back-end. Which is a RESTful API built with Django, and postgres database. At this point, I am thinking I need to verify my accessToken for authenticity, but I am unsure if I should be creating another PublicClient instance in python, and then sending the same commands to the IDP.
To guess at this point, I'm thinking this is wrong, as I need to verify the token, rather than get another Access and Refresh token. I'm thinking I just need to verify there is a session open with the IDP, and that the Access Token matches. Can anyone shed some light on this, possibly provide even just some direction.
The client Python Django Web App uses the Microsoft Authentication Library (MSAL) to sign-in and obtain an Access Token from Azure AD.
The access token is used as a bearer token to authorize the user to call the Python Flask Web API protected by Azure AD.
The Python Flask Web API then receives a token for Azure Resource Management API using the On-Behalf-Of flow.
To learn more about handing access token validation at the API layer, look into this sample walkthrough: https://github.com/Azure-Samples/ms-identity-python-on-behalf-of#about-the-code
https://learn.microsoft.com/en-us/azure/active-directory/develop/access-tokens#validating-tokens

How do I secure a Python API with in-the-open authorization tokens?

I have setup a simple REST API server (using Django REST framework) that responds to POST requests by doing some processing on an image uploaded to the server in the request. Previously I used it to power my own frontend (http://lips.kyleingraham.com) as a demonstration but I would now like to open the API to other users.
I would like for an end-user to be able to sign up and, from a dashboard, generate a token based on their credentials that could then be hard-coded into their web app. The sign-up part I believe I can handle but I am unclear on how to restrict a generated token to a user's web app domain. I know that the code for a web app is easily inspected so any API token I provide would need to be policed on my backend.
How can I restrict an authorization token to a users' web app domain so that even if the token was leaked, another user would not be able to utilize it?
If you want to hard-code url into user web app, in that way you can't guarantee that if someone get the token, he won't be able to use it.
The only idea is to set some time limit for each token

Integration of Angular website with SAML (SSO)

I have a website with frontend in AngularJS and backend in Python.
Currently we are presenting the user with a simple webform to fetch credentials.
The credentials from the form are sent to the Python backend(flask webservice)(this is a basic auth mechanism).
Now we would like to enable Single Sign on (SSO) on the website.Our identity provider is Pingone or Ping Federate.
I am starting from scratch here..with no prior knowledge of SAML or SSO.
I would like to know which path to take?
Which libraries to use and more importantly,how to use them?
At this point in time I am not sure how exactly SAML identifies a user and then authenticates him/her.
The basic exchange of SAML starts with a user asking for a resources (page, SPA app) on your Python server. The server determines if the user is already authenticated (has a session, JWT token, etc), and if not, creates a SAML request token to be sent via a redirect to the Identity Provider (use a library for this).
The identity provider verifies the SAML request token via digital signature. Once the token is verified, the user is asked to log in (if they are not already authenticated there). Once the user is authenticated, the identity provider creates a SAML request token which is presented back at your server via a redirect.
Upon receipt of the SAML request token, your server validates the token via digital signature, and you treat the user as logged in (again, use a library for this part). The token will minimally identify the user, but can contain authorizations and additional info. At this point your user is authenticated and you would create a session on your server or you create a JWT token to identify your user from within your angular app to the Python backend.
Creating the SAML request token and processing in the resultant SAML response token is not trivial. As suggested above, use a library, preferably one that has been through the the test of time. I'm not a Python dev, but I found this with some googling: onelogin/python-saml.
Wikipedia has a nice sequence diagram to demonstrate this and of course you can peruse the many docs on the Oasis SAML docs website.
Good luck with the implementation. I've done it a couple times in Java.

Frontend and backend hybrid oauth2 flow?

My app needs to retrieve user's dropbox data in both frontend when user is present(js) and backend when user is away(python/django)
I understand after authorization I will receive a token code. Does that mean I should use this token code for both JS and Python when communicating with Dropbox? or should I use my python backend as a proxy when communicating with Dropbox?
I am worried by using a proxy it will add unnecessary delay to the user experience.

How can I use Django OAuth Toolkit with Python Social Auth?

I'm building an API using Django Rest Framework. Later this API is supposed to be consumed by iOS and Android devices. I want to allow my users to sign-up with oauth2-providers like Facebook and Google. In this case, they shouldn't have to create an account with my platform at all. But users should also be able to sign-up when not having a Facebook/Google account, for which I'm using django-oauth-toolkit, so I have my own oauth2-provider.
For external providers I'm using python-social-auth, which works fine and automatically creates the user objects.
I want the clients to authenticate by using bearer tokens, which works fine for users that signed up with my provider (django-oauth-toolkit provides authentication scheme and permission classes for Django REST Framework).
However, python-social-auth only implements session based authentication, so there is no straightforward way to make authenticated API requests on behalf of users that registered by an external oauth2 provider.
If I use an access_token that has been generated by django-oauth-toolkit, doing a request like this works:
curl -v -H "Authorization: Bearer <token_generated_by_django-oauth-toolkit>" http://localhost:8000/api/
However, the following doesn't work since there is no corresponding authentication scheme for Django REST Framework and the AUTHENTICATION_BACKENDS provided by python-social-auth only work for session-based authentication:
curl -v -H "Authorization: Bearer <token_stored_by_python-social-auth>" http://localhost:8000/api/
Using the browseable API provided by Django REST Framework after authenticating with python-social-auth works just fine, only API calls without a session cookie don't work.
I'm wondering what the best approach is for this problem. The way I see it, I have basically two options:
A: When a user signs up with an external oauth2 provider (handled by python-social-auth), hook into the process to create an oauth2_provider.models.AccessToken and continue to use 'oauth2_provider.ext.rest_framework.OAuth2Authentication', now authenticating also users that registered with an external provider. This approach is suggested here:
https://groups.google.com/d/msg/django-rest-framework/ACKx1kY7kZM/YPWFA2DP9LwJ
B: Use python-social-auth for API request authentication. I could get my own users into python-social-auth by writing a custom backend and using register_by_access_token. However, since API calls cannot utilize Django sessions this would mean I would have to write an authentication scheme for Django Rest Framework that utilizes the data stored by python-social-auth. Some pointers on how to do this can be found here:
http://psa.matiasaguirre.net/docs/use_cases.html#signup-by-oauth-access-token
http://blog.wizer.fr/2013/11/angularjs-facebook-with-a-django-rest-api/
http://cbdev.blogspot.it/2014/02/facebook-login-with-angularjs-django.html
However, the way I understand it python-social-auth only verifies the token when doing a login and relies on the Django session afterwards. This would mean I would have to find a way to prevent python-social-auth from doing the whole oauth2-flow for each stateless API request and rather check against the data stored in the DB, which isn't really optimized for querying since it's stored as JSON (I could use UserSocialAuth.objects.get(extra_data__contains=) though).
I would also have to take care of verifying the scopes of an access token and use them to check permissions, something django-oauth-toolkit already does (TokenHasScope, required_scopes etc).
At the moment, I'm leaning towards using option A, since django-oauth-toolkit provides good integration with Django Rest Framework and I get everything I need out of the box. The only drawback is that I have to "inject" the access_tokens retrieved by python-social-auth into the AccessToken model of django-oauth-toolkit, which feels wrong somehow, but would probably be by far the easiest approach.
Does anybody have any objections on doing that or has maybe tackled the same problem in a different way? Am I missing something obvious and making my life harder than necessary?
If anybody has already integrated django-oauth-toolkit with python-social-auth and external oauth2 providers I would be very thankful for some pointers or opinions.
A lot of the difficulty in implementing OAuth comes down to understanding how the authorization flow is supposed to work. This is mostly because this is the "starting point" for logging in, and when working with a third-party backend (using something like Python Social Auth) you are actually doing this twice: once for your API and once for the third-party API.
Authorizing requests using your API and a third-party backend
The authentication process that you need is go through is:
Mobile App -> Your API : Authorization redirect
Your API -> Django Login : Displays login page
Django Login -> Facebook : User signs in
Facebook -> Django Login : User authorizes your API
Django Login -> Your API : User signs in
Your API -> Mobile App : User authorizes mobile app
I'm using "Facebook" as the third-party backend here, but the process is the same for any backend.
From the perspective of your mobile app, you are only redirecting to the /authorize url provided by Django OAuth Toolkit. From there, the mobile app waits until the callback url is reached, just like in the standard OAuth authorization flow. Almost everything else (Django login, social login, etc.) is handled by either Django OAuth Toolkit or Python Social Auth in the background.
This will also be compatible with pretty much any OAuth libraries that you use, and the authorization flow will work the same no matter what third party backend is used. It will even handle the (common) case where you need to be able to support Django's authentication backend (email/username and password) as well as a third-party login.
Mobile App -> Your API : Authorization redirect
Your API -> Django Login : Displays login page
Django Login -> Your API : User signs in
Your API -> Mobile App : User authorizes mobile app
What's also important to note here is that the mobile app (which could be any OAuth client) never receives the Facebook/third-party OAuth tokens. This is incredibly important, as it makes sure your API acts as an intermediary between the OAuth client and you user's social accounts.
Mobile App -> Your API : Authorization redirect
Your API -> Mobile App : Receives OAuth token
Mobile App -> Your API : Requests the display name
Your API -> Facebook : Requests the full name
Facebook -> Your API : Sends back the full name
Your API -> Mobile App : Send back a display name
Otherwise, the OAuth client would be able to bypass your API and make requests on your behalf to the third-party APIs.
Mobile App -> Your API : Authorization redirect
Your API -> Mobile App : Receives Facebook token
Mobile App -> Facebook : Requests all of the followers
Facebook -> Mobile App : Sends any requested data
You'll notice that at this point you would have lost all control over the third-party tokens. This is especially dangerous because most tokens can access a wide range of data, which opens the door to abuse and eventually goes down under your name. Most likely, those logging into your API/website did not intend on sharing their social information with the OAuth client, and were instead expecting you to keep that information private (as much as possible), but instead you are exposing that information to everyone.
Authenticating requests to your API
When the mobile application then uses your OAuth token to make requests to your API, all of the authentication happens through Django OAuth Toolkit (or your OAuth provider) in the background. All you see is that there is a User associated with your request.
Mobile App -> Your API : Sends request with OAuth token
Your API -> Django OAuth Toolkit : Verifies the token
Django OAuth Toolkit -> Your API : Returns the user who is authenticated
Your API -> Mobile App : Sends requested data back
This is important, because after the authorization stage it shouldn't make a difference if the user is coming from Facebook or Django's authentication system. Your API just needs a User to work with, and your OAuth provider should be able to handle the authentication and verification of the token.
This isn't much different from how Django REST framework authenticates the user when using session-backed authentication.
Web Browser -> Your API : Sends session cookie
Your API -> Django : Verifies session token
Django -> Your API : Returns session data
Your API -> Django : Verifies the user session
Django -> Your API : Returns the logged in user
Your API -> Web Browser : Returns the requested data
Again, all of this is handled by Django OAuth Toolkit and does not require extra work to implement.
Working with a native SDK
In most cases, you are going to be authenticating the user through your own website and using Python Social Auth to handle everything. But the one notable exception is when using a native SDK, as authentication and authorization is handled through the native system, which means you are bypassing your API entirely. This is great for applications which need to sign in with a third party, or applications which don't use your API at all, but it's a nightmare when both come together.
This is because your server can't validate the login and is forced to assume that the login is valid and genuine, which means it bypasses any and all security that Python Social Auth gives you.
Mobile App -> Facebook SDK : Opens the authorization prompt
Facebook SDK -> Mobile App : Gets the Facebook token
Mobile App -> Your API : Sends the Facebook token for authorization
Your API -> Django Login : Tries to validate the token
Django Login -> Your API : Returns a matching user
Your API -> Mobile App : Sends back an OAuth token for the user
You'll notice that this skips over your API during the authentication phase, and then forces your API to make assumptions about the token that is passed in. But there are definitely cases where this risk may be worth it, so you should evaluate that before throwing it out. It's a trade off between quick and native logins for your user and potentially handling bad or malicious tokens.
I solved it by using your A. option.
What I do is registering users that use a third party to sign up by their third party access token.
url(r'^register-by-token/(?P<backend>[^/]+)/$',
views.register_by_access_token),
This way, I can issue a GET request like this one:
GET http://localhost:8000/register-by-token/facebook/?access_token=123456
And register_by_access_token gets called. request.backend.do_auth will query the provider for the user info from the token and magically register a user account with the info or sign in the user if he's already registered.
Then, I create a token manually and return it as JSON for letting the client query my API.
from oauthlib.common import generate_token
...
#psa('social:complete')
def register_by_access_token(request, backend):
# This view expects an access_token GET parameter, if it's needed,
# request.backend and request.strategy will be loaded with the current
# backend and strategy.
third_party_token = request.GET.get('access_token')
user = request.backend.do_auth(third_party_token)
if user:
login(request, user)
# We get our app!
app = Application.objects.get(name="myapp")
# We delete the old token
try:
old = AccessToken.objects.get(user=user, application=app)
except:
pass
else:
old.delete()
# We create a new one
my_token = generate_token()
# We create the access token
# (we could create a refresh token too the same way)
AccessToken.objects.create(user=user,
application=app,
expires=now() + timedelta(days=365),
token=my_token)
return "OK" # you can return your token as JSON here
else:
return "ERROR"
I'm just not sure about the way I generate the token, is this good practice? Well, in the mean time, it works!!
Maybe django-rest-framework-social-oauth2 is what you're looking for. This package depends on python-social-auth and django-oauth-toolkit, which you already use. I quickly scanned through the documentation, and it seems to implement just what you are trying to do.
I was doing React Native with expo and Django with Django REST framework. This blogpost ended being the way I solved registration (signup) with facebook https://medium.com/#gabriel_gamil/react-native-expo-django-facebook-authentication-sign-in-83625c49da7
tldr; use django-rest-auth https://django-rest-auth.readthedocs.io/en/latest/index.html
use Django-allauth https://django-allauth.readthedocs.io/en/latest/

Categories

Resources