authorize subsets of roles

- oauth clients can request a list of roles
- authorization will proceed with the _subset_ of those roles held by the user
- in the future, this subsetting will be refined to the scope level

examples/custom-scopes/grades.py

@@ -43,13 +43,31 @@ def require_scope(scopes):
     return wrap
 
 
+class MyGradesHandler(HubOAuthenticated, RequestHandler):
+    # no hub_scopes, anyone with access to this service
+    # will be able to visit this URL
+
+    @authenticated
+    def get(self):
+        self.write("<h1>My grade</h1>")
+        name = self.current_user["name"]
+        grades = self.settings["grades"]
+        self.write(f"<p>My name is: {escape(name)}</p>")
+        if name in grades:
+            self.write(f"<p>My grade is: {escape(str(grades[name]))}</p>")
+        else:
+            self.write("<p>No grade entered</p>")
+        if READ_SCOPE in self.current_user["scopes"]:
+            self.write('<a href="grades/">enter grades</a>')
+
+
 class GradesHandler(HubOAuthenticated, RequestHandler):
     # default scope for this Handler: read-only
     hub_scopes = [READ_SCOPE]
 
     def _render(self):
         grades = self.settings["grades"]
-        self.write("<h1>Grades</h1>")
+        self.write("<h1>All grades</h1>")
         self.write("<table>")
         self.write("<tr><th>Student</th><th>Grade</th></tr>")
         for student, grade in grades.items():
@@ -92,7 +110,8 @@ def main():
 
     app = Application(
         [
-            (base_url, GradesHandler),
+            (base_url, MyGradesHandler),
+            (url_path_join(base_url, 'grades/'), GradesHandler),
             (
                 url_path_join(base_url, 'oauth_callback'),
                 HubOAuthCallbackHandler,

examples/custom-scopes/jupyterhub_config.py

@@ -31,7 +31,13 @@ c.JupyterHub.load_roles = [
         "name": "grader",
         # grant graders access to write grades
         "scopes": ["custom:grades:write"],
-        "users": ["grader", "instructor"],
+        "users": ["grader"],
+    },
+    {
+        "name": "instructor",
+        # grant instructors access to read, but not write grades
+        "scopes": ["custom:grades:read"],
+        "users": ["instructor"],
     },
 ]
 

jupyterhub/apihandlers/auth.py

@@ -283,6 +283,21 @@ class OAuthAuthorizeHandler(OAuthHandler, BaseHandler):
                 raise web.HTTPError(
                     403, f"You do not have permission to access {client.description}"
                 )
+
+            # subset role names to those held by authenticating user
+            requested_role_names = set(role_names)
+            user = self.current_user
+            user_role_names = {role.name for role in user.roles}
+            allowed_role_names = requested_role_names.intersection(user_role_names)
+            excluded_role_names = requested_role_names.difference(allowed_role_names)
+            if excluded_role_names:
+                self.log.info(
+                    f"Service {client.description} requested roles {','.join(role_names)}"
+                    f" for user {self.current_user.name},"
+                    f" granting only {','.join(allowed_role_names) or '[]'}."
+                )
+                role_names = list(allowed_role_names)
+
             if not self.needs_oauth_confirm(self.current_user, client, role_names):
                 self.log.debug(
                     "Skipping oauth confirmation for %s accessing %s",
@@ -381,6 +396,10 @@ class OAuthAuthorizeHandler(OAuthHandler, BaseHandler):
         # The scopes the user actually authorized, i.e. checkboxes
         # that were selected.
         scopes = self.get_arguments('scopes')
+        if scopes == []:
+            # avoid triggering default scopes (provider selects default scopes when scopes is falsy)
+            # when an explicit empty list is authorized
+            scopes = ["identify"]
         # credentials we need in the validator
         credentials = self.add_credentials()
 

jupyterhub/tests/mockservice.py

@@ -23,6 +23,7 @@ from tornado import httpserver
 from tornado import ioloop
 from tornado import log
 from tornado import web
+from tornado.httputil import url_concat
 
 from jupyterhub.services.auth import HubAuthenticated
 from jupyterhub.services.auth import HubOAuthCallbackHandler
@@ -76,6 +77,13 @@ class OWhoAmIHandler(HubOAuthenticated, web.RequestHandler):
     Uses OAuth login flow
     """
 
+    def get_login_url(self):
+        login_url = super().get_login_url()
+        scopes = self.get_argument("request-scope", None)
+        if scopes is not None:
+            login_url = url_concat(login_url, {"scope": scopes})
+        return login_url
+
     @web.authenticated
     def get(self):
         self.write(self.get_current_user())

jupyterhub/tests/test_pages.py

@@ -1134,6 +1134,7 @@ async def test_oauth_page_scope_appearance(
     )
     service = mockservice_url
     user = create_user_with_scopes("access:services")
+    roles.grant_role(app.db, user, service_role)
     oauth_client = (
         app.db.query(orm.OAuthClient)
         .filter_by(identifier=service.oauth_client_id)

jupyterhub/tests/test_services_auth.py

@@ -5,9 +5,11 @@ import sys
 from binascii import hexlify
 from unittest import mock
 from urllib.parse import parse_qs
+from urllib.parse import quote
 from urllib.parse import urlparse
 
 import pytest
+from bs4 import BeautifulSoup
 from pytest import raises
 from tornado.httputil import url_concat
 
@@ -227,6 +229,9 @@ async def test_hubauth_service_token(request, app, mockservice_url, scopes, allo
         (["admin", "user"], ["user"], ["user"]),
         (["user", "token", "server"], ["token", "user"], ["token", "user"]),
         (["admin", "user", "read-only"], ["read-only"], ["read-only"]),
+        # requesting valid subset, some not held by user
+        (["admin", "user"], ["admin", "user"], ["user"]),
+        (["admin", "user"], ["admin"], []),
     ],
 )
 async def test_oauth_service_roles(
@@ -267,6 +272,8 @@ async def test_oauth_service_roles(
     ]
     app.db.commit()
     url = url_path_join(public_url(app, mockservice_url) + 'owhoami/?arg=x')
+    if request_roles:
+        url = url_concat(url, {"request-scope": " ".join(request_roles)})
     # first request is only going to login and get us to the oauth form page
     s = AsyncSession()
     user = create_user_with_scopes("access:services")
@@ -276,17 +283,6 @@ async def test_oauth_service_roles(
     s.cookies = await app.login_user(name)
 
     r = await s.get(url)
-    r.raise_for_status()
-    # we should be looking at the oauth confirmation page
-    assert urlparse(r.url).path == app.base_url + 'hub/api/oauth2/authorize'
-    # verify oauth state cookie was set at some point
-    assert set(r.history[0].cookies.keys()) == {'service-%s-oauth-state' % service.name}
-
-    # submit the oauth form to complete authorization
-    data = {}
-    if request_roles:
-        data["scopes"] = request_roles
-    r = await s.post(r.url, data=data, headers={'Referer': r.url})
     if expected_roles is None:
         # expected failed auth, stop here
         # verify expected 'invalid scope' error, not server error
@@ -296,6 +292,21 @@ async def test_oauth_service_roles(
         assert r.status_code == 400
         return
     r.raise_for_status()
+    # we should be looking at the oauth confirmation page
+    assert urlparse(r.url).path == app.base_url + 'hub/api/oauth2/authorize'
+    # verify oauth state cookie was set at some point
+    assert set(r.history[0].cookies.keys()) == {'service-%s-oauth-state' % service.name}
+
+    page = BeautifulSoup(r.text, "html.parser")
+    scope_inputs = page.find_all("input", {"name": "scopes"})
+    scope_values = [input["value"] for input in scope_inputs]
+    print("Submitting request with scope values", scope_values)
+    # submit the oauth form to complete authorization
+    data = {}
+    if scope_values:
+        data["scopes"] = scope_values
+    r = await s.post(r.url, data=data, headers={'Referer': r.url})
+    r.raise_for_status()
     assert r.url == url
     # verify oauth cookie is set
     assert 'service-%s' % service.name in set(s.cookies.keys())
@@ -395,7 +406,11 @@ async def test_oauth_access_scopes(
 
 @pytest.mark.parametrize(
     "token_roles, hits_page",
-    [([], True), (['writer'], True), (['writer', 'reader'], False)],
+    [
+        ([], True),
+        (['writer'], True),
+        (['writer', 'reader'], False),
+    ],
 )
 async def test_oauth_page_hit(
     app,
@@ -411,6 +426,8 @@ async def test_oauth_page_hit(
     }
     service = mockservice_url
     user = create_user_with_scopes("access:services", "self")
+    for role in test_roles.values():
+        roles.grant_role(app.db, user, role)
     user.new_api_token()
     token = user.api_tokens[0]
     token.roles = [test_roles[t] for t in token_roles]