Authentication & Authorization

OAuth token-based authentication & authorization

Pleroma supports hierarchical OAuth scopes, just like Mastodon but with added granularity of admin scopes. For a reference, see Mastodon OAuth scopes.
It is important to either define OAuth scope restrictions or explicitly mark OAuth scope check as skipped, for every controller action. To define scopes, call plug(Pleroma.Plugs.OAuthScopesPlug, %{scopes: [...]}). To explicitly set OAuth scopes check skipped, call plug(:skip_plug, Pleroma.Plugs.OAuthScopesPlug <when ...>).
In controllers, use Pleroma.Web, :controller will result in action/2 (see Pleroma.Web.controller/0 for definition) be called prior to actual controller action, and it'll perform security / privacy checks before passing control to actual controller action. For routes with :authenticated_api pipeline, authentication & authorization are expected, thus OAuthScopesPlug will be run unless explicitly skipped (also EnsureAuthenticatedPlug will be executed immediately before action even if there was an early run to give an early error, since OAuthScopesPlug supports :proceed_unauthenticated option, and other plugs may support similar options as well). For :api pipeline routes, EnsurePublicOrAuthenticatedPlug will be called to ensure that the instance is not private or user is authenticated (unless explicitly skipped). Such automated checks help to prevent human errors and result in higher security / privacy for users.

With HTTP Basic Auth, OAuth scopes check is not performed for any action (since password is provided during the auth, requester is able to obtain a token with full permissions anyways). Pleroma.Plugs.AuthenticationPlug and Pleroma.Plugs.LegacyAuthenticationPlug both call Pleroma.Plugs.OAuthScopesPlug.skip_plug(conn) when password is provided.