🔧(backend) configure Authorization Code authentication

Integrate 'mozilla-django-oidc' dependency, to support
Authorization Code flow, which is required by Agent Connect.

Thus, we provide a secure back channel OIDC flow, and return
to the client only a session cookie.

Done:
- Replace JWT authentication by Session based authentication in DRF
- Update Django settings to make OIDC configurations easily editable
- Add 'mozilla-django-oidc' routes to our router
- Implement a custom Django Authentication class to adapt
'mozilla-django-oidc' to our needs

'mozilla-django-oidc' routes added are:
- /authenticate
- /callback (the redirect_uri called back by the Idp)
- /logout

.github/workflows/publish.yml

@@ -130,7 +130,7 @@ jobs:
       DJANGO_CONFIGURATION: Test
       DJANGO_SETTINGS_MODULE: publish.settings
       DJANGO_SECRET_KEY: ThisIsAnExampleKeyForTestPurposeOnly
-      DJANGO_JWT_PRIVATE_SIGNING_KEY: ThisIsAnExampleKeyForDevPurposeOnly
+      OIDC_OP_JWKS_ENDPOINT: /endpoint-for-test-purpose-only
       DB_HOST: localhost
       DB_NAME: publish
       DB_USER: dinum

Dockerfile

@@ -55,7 +55,7 @@ COPY ./src/backend /app/
 WORKDIR /app
 
 # collectstatic
-RUN DJANGO_CONFIGURATION=Build DJANGO_JWT_PRIVATE_SIGNING_KEY=Dummy \
+RUN DJANGO_CONFIGURATION=Build \
     python manage.py collectstatic --noinput
 
 # Replace duplicated file by a symlink to decrease the overall size of the

env.d/development/common.dist

@@ -7,9 +7,6 @@ DJANGO_SUPERUSER_PASSWORD=admin
 # Python
 PYTHONPATH=/app
 
-#JWT
-DJANGO_JWT_PRIVATE_SIGNING_KEY=ThisIsAnExampleKeyForDevPurposeOnly
-
 # publish settings
 
 # Mail
@@ -18,3 +15,21 @@ DJANGO_EMAIL_PORT=1025
 
 # Backend url
 publish_BASE_URL="http://localhost:8072"
+
+# OIDC
+OIDC_OP_JWKS_ENDPOINT=http://nginx:8083/realms/impress/protocol/openid-connect/certs
+OIDC_OP_AUTHORIZATION_ENDPOINT=http://localhost:8083/realms/impress/protocol/openid-connect/auth
+OIDC_OP_TOKEN_ENDPOINT=http://nginx:8083/realms/impress/protocol/openid-connect/token
+OIDC_OP_USER_ENDPOINT=http://nginx:8083/realms/impress/protocol/openid-connect/userinfo
+
+OIDC_RP_CLIENT_ID=impress
+OIDC_RP_CLIENT_SECRET=ThisIsAnExampleKeyForDevPurposeOnly
+OIDC_RP_SIGN_ALGO=RS256
+OIDC_RP_SCOPES="openid email"
+
+LOGIN_REDIRECT_URL=http://localhost:3000
+LOGIN_REDIRECT_URL_FAILURE=http://localhost:3000
+LOGOUT_REDIRECT_URL=http://localhost:3000
+
+OIDC_REDIRECT_ALLOWED_HOSTS=["http://localhost:8083", "http://localhost:3000"]
+OIDC_AUTH_REQUEST_EXTRA_PARAMS={"acr_values": "eidas1"}

src/backend/core/api/utils.py

@@ -1,14 +0,0 @@
-"""
-Utils that can be useful throughout the publish core app
-"""
-from rest_framework_simplejwt.tokens import RefreshToken
-
-
-def get_tokens_for_user(user):
-    """Get JWT tokens for user authentication."""
-    refresh = RefreshToken.for_user(user)
-
-    return {
-        "refresh": str(refresh),
-        "access": str(refresh.access_token),
-    }

src/backend/core/authentication.py

@@ -1,59 +1,100 @@
-"""Authentication for the publish core app."""
+"""Authentication for the Impress core app."""
-from django.conf import settings
+
-from django.utils.functional import SimpleLazyObject
+from django.core.exceptions import SuspiciousOperation
-from django.utils.module_loading import import_string
 from django.utils.translation import gettext_lazy as _
 
-from drf_spectacular.authentication import SessionScheme, TokenScheme
+import requests
-from drf_spectacular.plumbing import build_bearer_security_scheme_object
+from mozilla_django_oidc.auth import (
-from rest_framework import authentication
+    OIDCAuthenticationBackend as MozillaOIDCAuthenticationBackend,
-from rest_framework_simplejwt.authentication import JWTAuthentication
-
-
-class DelegatedJWTAuthentication(JWTAuthentication):
-    """Override JWTAuthentication to create missing users on the fly."""
-
-    def get_user(self, validated_token):
-        """
-        Return the user related to the given validated token, creating or updating it if necessary.
-        """
-        get_user = import_string(settings.JWT_USER_GETTER)
-        return SimpleLazyObject(lambda: get_user(validated_token))
-
-
-class OpenApiJWTAuthenticationExtension(TokenScheme):
-    """Extension for specifying JWT authentication schemes."""
-
-    target_class = "core.authentication.DelegatedJWTAuthentication"
-    name = "DelegatedJWTAuthentication"
-
-    def get_security_definition(self, auto_schema):
-        """Return the security definition for JWT authentication."""
-        return build_bearer_security_scheme_object(
-            header_name="Authorization",
-            token_prefix="Bearer",  # noqa S106
 )
 
+from .models import User
 
-class SessionAuthenticationWithAuthenticateHeader(authentication.SessionAuthentication):
-    """
-    This class is needed, because REST Framework's default SessionAuthentication does
-    never return 401's, because they cannot fill the WWW-Authenticate header with a
-    valid value in the 401 response. As a result, we cannot distinguish calls that are
-    not unauthorized (401 unauthorized) and calls for which the user does not have
-    permission (403 forbidden).
-    See https://github.com/encode/django-rest-framework/issues/5968
 
-    We do set authenticate_header function in SessionAuthentication, so that a value
+class OIDCAuthenticationBackend(MozillaOIDCAuthenticationBackend):
-    for the WWW-Authenticate header can be retrieved and the response code is
+    """Custom OpenID Connect (OIDC) Authentication Backend.
-    automatically set to 401 in case of unauthenticated requests.
+
+    This class overrides the default OIDC Authentication Backend to accommodate differences
+    in the User and Identity models, and handles signed and/or encrypted UserInfo response.
     """
 
-    def authenticate_header(self, request):
+    def get_userinfo(self, access_token, id_token, payload):
-        return "Session"
+        """Return user details dictionary.
 
+        Parameters:
+        - access_token (str): The access token.
+        - id_token (str): The id token (unused).
+        - payload (dict): The token payload (unused).
 
-class OpenApiSessionAuthenticationExtension(SessionScheme):
+        Note: The id_token and payload parameters are unused in this implementation,
-    """Extension for specifying session authentication schemes."""
+        but were kept to preserve base method signature.
 
-    target_class = "core.api.authentication.SessionAuthenticationWithAuthenticateHeader"
+        Note: It handles signed and/or encrypted UserInfo Response. It is required by
+        Agent Connect, which follows the OIDC standard. It forces us to override the
+        base method, which deal with 'application/json' response.
+
+        Returns:
+        - dict: User details dictionary obtained from the OpenID Connect user endpoint.
+        """
+
+        user_response = requests.get(
+            self.OIDC_OP_USER_ENDPOINT,
+            headers={"Authorization": f"Bearer {access_token}"},
+            verify=self.get_settings("OIDC_VERIFY_SSL", True),
+            timeout=self.get_settings("OIDC_TIMEOUT", None),
+            proxies=self.get_settings("OIDC_PROXY", None),
+        )
+        user_response.raise_for_status()
+        userinfo = self.verify_token(user_response.text)
+        return userinfo
+
+    def get_or_create_user(self, access_token, id_token, payload):
+        """Return a User based on userinfo. Get or create a new user if no user matches the Sub.
+
+        Parameters:
+        - access_token (str): The access token.
+        - id_token (str): The ID token.
+        - payload (dict): The user payload.
+
+        Returns:
+        - User: An existing or newly created User instance.
+
+        Raises:
+        - Exception: Raised when user creation is not allowed and no existing user is found.
+        """
+
+        user_info = self.get_userinfo(access_token, id_token, payload)
+        sub = user_info.get("sub")
+
+        if sub is None:
+            raise SuspiciousOperation(
+                _("User info contained no recognizable user identification")
+            )
+
+        try:
+            user = User.objects.get(sub=sub)
+        except User.DoesNotExist:
+            if self.get_settings("OIDC_CREATE_USER", True):
+                user = self.create_user(user_info)
+            else:
+                user = None
+
+        return user
+
+    def create_user(self, claims):
+        """Return a newly created User instance."""
+
+        sub = claims.get("sub")
+
+        if sub is None:
+            raise SuspiciousOperation(
+                _("Claims contained no recognizable user identification")
+            )
+
+        user = User.objects.create(
+            sub=sub,
+            email=claims.get("email"),
+            password="!",  # noqa: S106
+        )
+
+        return user

src/backend/core/models.py

@@ -16,8 +16,6 @@ from django.utils.translation import gettext_lazy as _
 
 import frontmatter
 import markdown
-from rest_framework_simplejwt.exceptions import InvalidToken
-from rest_framework_simplejwt.settings import api_settings
 from timezone_field import TimeZoneField
 from weasyprint import CSS, HTML
 from weasyprint.text.fonts import FontConfiguration
@@ -331,27 +329,3 @@ class TemplateAccess(BaseModel):
             "retrieve": bool(role),
             "set_role_to": set_role_to,
         }
-
-
-def oidc_user_getter(validated_token):
-    """
-    Given a valid OIDC token , retrieve, create or update corresponding user/contact/email from db.
-
-    The token is expected to have the following fields in payload:
-        - sub
-        - email
-        - ...
-    """
-    try:
-        user_id = validated_token[api_settings.USER_ID_CLAIM]
-    except KeyError as exc:
-        raise InvalidToken(
-            _("Token contained no recognizable user identification")
-        ) from exc
-
-    try:
-        user = User.objects.get(sub=user_id)
-    except User.DoesNotExist:
-        user = User.objects.create(sub=user_id, email=validated_token.get("email"))
-
-    return user

src/backend/core/tests/utils.py

@@ -1,15 +0,0 @@
-"""Utils for tests in the publish core application"""
-from rest_framework_simplejwt.tokens import AccessToken
-
-
-class OIDCToken(AccessToken):
-    """Set payload on token from user/contact/email"""
-
-    @classmethod
-    def for_user(cls, user):
-        """Returns an authorization token for the given user for testing."""
-        token = cls()
-        token["sub"] = str(user.sub)
-        token["email"] = user.email
-
-        return token

src/backend/core/urls.py

@@ -2,6 +2,7 @@
 from django.conf import settings
 from django.urls import include, path, re_path
 
+from mozilla_django_oidc.urls import urlpatterns as oidc_urls
 from rest_framework.routers import DefaultRouter
 
 from core.api import viewsets
@@ -26,6 +27,7 @@ urlpatterns = [
         include(
             [
                 *router.urls,
+                *oidc_urls,
                 re_path(
                     r"^templates/(?P<template_id>[0-9a-z-]*)/",
                     include(template_related_router.urls),

src/backend/publish/settings.py

@@ -181,6 +181,7 @@ class Base(Configuration):
 
     AUTHENTICATION_BACKENDS = [
         "django.contrib.auth.backends.ModelBackend",
+        "core.authentication.OIDCAuthenticationBackend",
     ]
 
     # Django applications from the highest priority to the lowest
@@ -204,6 +205,8 @@ class Base(Configuration):
         "django.contrib.sites",
         "django.contrib.messages",
         "django.contrib.staticfiles",
+        # OIDC third party
+        "mozilla_django_oidc",
     ]
 
     # Cache
@@ -213,7 +216,8 @@ class Base(Configuration):
 
     REST_FRAMEWORK = {
         "DEFAULT_AUTHENTICATION_CLASSES": (
-            "core.authentication.DelegatedJWTAuthentication",
+            "mozilla_django_oidc.contrib.drf.OIDCAuthentication",
+            "rest_framework.authentication.SessionAuthentication",
         ),
         "DEFAULT_PARSER_CLASSES": [
             "rest_framework.parsers.JSONParser",
@@ -242,23 +246,6 @@ class Base(Configuration):
         "REDOC_DIST": "SIDECAR",
     }
 
-    SIMPLE_JWT = {
-        "ALGORITHM": values.Value("HS256", environ_name="JWT_ALGORITHM"),
-        "SIGNING_KEY": values.SecretValue(
-            environ_name="JWT_PRIVATE_SIGNING_KEY",
-        ),
-        "AUTH_HEADER_TYPES": ("Bearer",),
-        "AUTH_HEADER_NAME": "HTTP_AUTHORIZATION",
-        "USER_ID_FIELD": "sub",
-        "USER_ID_CLAIM": "sub",
-        "AUTH_TOKEN_CLASSES": ("rest_framework_simplejwt.tokens.AccessToken",),
-    }
-    JWT_USER_GETTER = values.Value(
-        "core.models.oidc_user_getter",
-        environ_name="publish_JWT_USER_GETTER",
-        environ_prefix=None,
-    )
-
     # Mail
     EMAIL_BACKEND = values.Value("django.core.mail.backends.smtp.EmailBackend")
     EMAIL_HOST = values.Value(None)
@@ -288,6 +275,63 @@ class Base(Configuration):
     CELERY_BROKER_URL = values.Value("redis://redis:6379/0")
     CELERY_BROKER_TRANSPORT_OPTIONS = values.DictValue({})
 
+    # Session
+    SESSION_ENGINE = "django.contrib.sessions.backends.cache"
+    SESSION_COOKIE_AGE = 60 * 60 * 12
+
+    # OIDC - Authorization Code Flow
+    OIDC_CREATE_USER = values.BooleanValue(
+        default=True,
+        environ_name="OIDC_CREATE_USER",
+    )
+    OIDC_RP_SIGN_ALGO = values.Value(
+        "RS256", environ_name="OIDC_RP_SIGN_ALGO", environ_prefix=None
+    )
+    OIDC_RP_CLIENT_ID = values.Value(
+        "impress", environ_name="OIDC_RP_CLIENT_ID", environ_prefix=None
+    )
+    OIDC_RP_CLIENT_SECRET = values.Value(
+        None,
+        environ_name="OIDC_RP_CLIENT_SECRET",
+        environ_prefix=None,
+    )
+    OIDC_OP_JWKS_ENDPOINT = values.Value(
+        environ_name="OIDC_OP_JWKS_ENDPOINT", environ_prefix=None
+    )
+    OIDC_OP_AUTHORIZATION_ENDPOINT = values.Value(
+        environ_name="OIDC_OP_AUTHORIZATION_ENDPOINT", environ_prefix=None
+    )
+    OIDC_OP_TOKEN_ENDPOINT = values.Value(
+        None, environ_name="OIDC_OP_TOKEN_ENDPOINT", environ_prefix=None
+    )
+    OIDC_OP_USER_ENDPOINT = values.Value(
+        None, environ_name="OIDC_OP_USER_ENDPOINT", environ_prefix=None
+    )
+    OIDC_AUTH_REQUEST_EXTRA_PARAMS = values.DictValue(
+        {}, environ_name="OIDC_AUTH_REQUEST_EXTRA_PARAMS", environ_prefix=None
+    )
+    OIDC_RP_SCOPES = values.Value(
+        "openid email", environ_name="OIDC_RP_SCOPES", environ_prefix=None
+    )
+    LOGIN_REDIRECT_URL = values.Value(
+        None, environ_name="LOGIN_REDIRECT_URL", environ_prefix=None
+    )
+    LOGIN_REDIRECT_URL_FAILURE = values.Value(
+        None, environ_name="LOGIN_REDIRECT_URL_FAILURE", environ_prefix=None
+    )
+    LOGOUT_REDIRECT_URL = values.Value(
+        None, environ_name="LOGOUT_REDIRECT_URL", environ_prefix=None
+    )
+    OIDC_USE_NONCE = values.BooleanValue(
+        default=True, environ_name="OIDC_USE_NONCE", environ_prefix=None
+    )
+    OIDC_REDIRECT_REQUIRE_HTTPS = values.BooleanValue(
+        default=False, environ_name="OIDC_REDIRECT_REQUIRE_HTTPS", environ_prefix=None
+    )
+    OIDC_REDIRECT_ALLOWED_HOSTS = values.ListValue(
+        default=[], environ_name="OIDC_REDIRECT_ALLOWED_HOSTS", environ_prefix=None
+    )
+
     # pylint: disable=invalid-name
     @property
     def ENVIRONMENT(self):

src/backend/pyproject.toml

@@ -35,7 +35,6 @@ dependencies = [
     "django-storages==1.14.2",
     "django-timezone-field>=5.1",
     "django==5.0.2",
-    "djangorestframework-simplejwt==5.3.0",
     "djangorestframework==3.14.0",
     "drf_spectacular==0.26.5",
     "dockerflow==2022.8.0",
@@ -53,6 +52,7 @@ dependencies = [
     "url-normalize==1.4.3",
     "WeasyPrint>=60.2",
     "whitenoise==6.6.0",
+    "mozilla-django-oidc==4.0.0",
 ]
 
 [project.urls]