Security: login_required decorator never validates token expiry

[miceg]

This issue is for a: (mark with an x)

- [x] bug report -> please search issues before submitting
- [ ] feature request
- [ ] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)

Minimal steps to reproduce

Sample views in this project are wrapped with a @login_required decorator:

ms-identity-python-django-tutorial/1-Authentication/sign-in/Sample/views.py

Lines 10 to 15 in bda4319

	@ms_identity_web.login_required
	def token_details(request):
	return render(request, 'auth/token.html')
	@ms_identity_web.login_required
	def call_ms_graph(request):

That login_required decorator isn't as robust as Django's normal login_required decorator. It notes that checking token expiry is not implemented:

https://github.com/Azure-Samples/ms-identity-python-samples-common/blob/9b32cef36c6c0b73c1b3237fdd66128d89f90a62/ms_identity_web/__init__.py#L278-L291

identity_context_data is stored in a Django session (DjangoContextAdapter), which itself says "the following class is incomplete":

https://github.com/Azure-Samples/ms-identity-python-samples-common/blob/9b32cef36c6c0b73c1b3237fdd66128d89f90a62/ms_identity_web/adapters.py#L222-L223

This sample (and library code) allows established MS Identity sessions to live forever, as long as you can get Django to extend the session's lifetime (which it does whenever "saving" to the session) at least (by default) every 2 weeks.

This doesn't affect the use of the token with APIs that validate the expiry time.

Expected/desired behavior

Using an expired authentication token should not work on views with the @login_required decorator.

OS and Version?

any/all

Versions

Using current main branch of ms-identity-samples-common and ms-identity-python-django-tutorial.

Mention any other details that might be useful

While the bug is in https://github.com/Azure-Samples/ms-identity-python-samples-common/, this decorator only appears to be used in the context of this sample.