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The authorization rules that secure your application’s backend often have implications for the frontend user interface (UI) as well. For example, if a user does not have access to a specific page the UI should hide that link. Similarly, if a user can only read a resource, the UI may gray out an edit button. This guide covers the best practices for implementing frontend (UI) authorization with Oso Cloud.

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Keep Enforcement in the Backend

The first rule of frontend authorization: keep the user interface in charge of presentation and the backend service in charge of enforcement. Because the end user has total control over code that runs in their browser, you can never trust requests from the UI. The user might represent as an administrator who should have unfettered access to your entire application. But thebackend service should request an authorization decision from Oso Cloud to confirm what they are permitted to do.
For security reasons, you should never make requests directly to Oso Cloud from your frontend. Your Oso Cloud API token should be kept secret and never exposed in a user interface. A malicious actor could use even a read-only API token to exfiltrate your sensitive authorization policy and data.

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Expose Permissions to the Frontend

UIs ask a single authorization question over and over: what actions can the current user perform on resources rendered on the current page? If the user can view an organization but does not have permission to edit or delete it, the user interface should not render Edit or Delete buttons. The general pattern for a backend service responding to an user interface request:
  • Ask Oso Cloud via the Authorize API: is the user authorized to access the resource?
  • If they have access, what actions can the user take on the resource?
  • Return the permissions along with the response payload so that your UI can render the approriate experience based on what the user can and cannot do.
Here’s an example of that pattern in our GitCloud example app’s Python back end: 
def show_organization(org_id):
		# Is the current user authorized to access the resource?
    if not oso.authorize(current_user, "read", {"type": "Organization", "id": org_id}):
        raise NotFound

    org = Organization.get_from_database(org_id)
    json = org.as_json()

		# What actions can the current user take on the resource?
    actions = oso.actions(current_user, org)

    # Return the permissions along with the response payload.
    json["permissions"] = actions
    return json
The UI then uses the returned permissions to decide whether to show or hide specific elements. Here’s an example from GitCloud’s React front end: 
{
  org.permissions?.includes("create_repositories") && (
    <Button>Create new repository</Button>
  );
}
We only show the Create new repository button if the current user has the "create_repositories" permission on the organization.

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