Record the SSO Auth Provider in the login token

changelog.d/9510.feature

@@ -0,0 +1 @@
+Add prometheus metrics for number of users successfully registering and logging in.

mypy.ini

@@ -69,6 +69,7 @@ files =
   synapse/util/async_helpers.py,
   synapse/util/caches,
   synapse/util/metrics.py,
+  synapse/util/macaroons.py,
   synapse/util/stringutils.py,
   tests/replication,
   tests/test_utils,

synapse/api/auth.py

@@ -39,6 +39,7 @@
 from synapse.storage.databases.main.registration import TokenLookupResult
 from synapse.types import StateMap, UserID
 from synapse.util.caches.lrucache import LruCache
+from synapse.util.macaroons import get_value_from_macaroon, satisfy_expiry
 from synapse.util.metrics import Measure
 
 logger = logging.getLogger(__name__)
@@ -408,43 +409,27 @@ def _parse_and_validate_macaroon(self, token, rights="access"):
             raise _InvalidMacaroonException()
 
         try:
-            user_id = self.get_user_id_from_macaroon(macaroon)
+            user_id = get_value_from_macaroon(macaroon, "user_id")
 
             guest = False
             for caveat in macaroon.caveats:
                 if caveat.caveat_id == "guest = true":
                     guest = True
 
             self.validate_macaroon(macaroon, rights, user_id=user_id)
-        except (pymacaroons.exceptions.MacaroonException, TypeError, ValueError):
+        except (
+            pymacaroons.exceptions.MacaroonException,
+            KeyError,
+            TypeError,
+            ValueError,
+        ):
             raise InvalidClientTokenError("Invalid macaroon passed.")
 
         if rights == "access":
             self.token_cache[token] = (user_id, guest)
 
         return user_id, guest
 
-    def get_user_id_from_macaroon(self, macaroon):
-        """Retrieve the user_id given by the caveats on the macaroon.
-
-        Does *not* validate the macaroon.
-
-        Args:
-            macaroon (pymacaroons.Macaroon): The macaroon to validate
-
-        Returns:
-            (str) user id
-
-        Raises:
-            InvalidClientCredentialsError if there is no user_id caveat in the
-                macaroon
-        """
-        user_prefix = "user_id = "
-        for caveat in macaroon.caveats:
-            if caveat.caveat_id.startswith(user_prefix):
-                return caveat.caveat_id[len(user_prefix) :]
-        raise InvalidClientTokenError("No user caveat in macaroon")
-
     def validate_macaroon(self, macaroon, type_string, user_id):
         """
         validate that a Macaroon is understood by and was signed by this server.
@@ -465,21 +450,13 @@ def validate_macaroon(self, macaroon, type_string, user_id):
         v.satisfy_exact("type = " + type_string)
         v.satisfy_exact("user_id = %s" % user_id)
         v.satisfy_exact("guest = true")
-        v.satisfy_general(self._verify_expiry)
+        satisfy_expiry(v, self.clock.time_msec)
 
         # access_tokens include a nonce for uniqueness: any value is acceptable
         v.satisfy_general(lambda c: c.startswith("nonce = "))
 
         v.verify(macaroon, self._macaroon_secret_key)
 
-    def _verify_expiry(self, caveat):
-        prefix = "time < "
-        if not caveat.startswith(prefix):
-            return False
-        expiry = int(caveat[len(prefix) :])
-        now = self.hs.get_clock().time_msec()
-        return now < expiry
-
     def get_appservice_by_req(self, request: SynapseRequest) -> ApplicationService:
         token = self.get_access_token_from_request(request)
         service = self.store.get_app_service_by_token(token)

synapse/handlers/auth.py

@@ -65,6 +65,7 @@
 from synapse.types import JsonDict, Requester, UserID
 from synapse.util import stringutils as stringutils
 from synapse.util.async_helpers import maybe_awaitable
+from synapse.util.macaroons import get_value_from_macaroon, satisfy_expiry
 from synapse.util.msisdn import phone_number_to_msisdn
 from synapse.util.threepids import canonicalise_email
 
@@ -170,6 +171,16 @@ class SsoLoginExtraAttributes:
     extra_attributes = attr.ib(type=JsonDict)
 
 
+@attr.s(slots=True, frozen=True)
+class LoginTokenAttributes:
+    """Data we store in a short-term login token"""
+
+    user_id = attr.ib(type=str)
+
+    # the SSO Identity Provider that the user authenticated with, to get this token
+    auth_provider_id = attr.ib(type=Optional[str])
+
+
 class AuthHandler(BaseHandler):
     SESSION_EXPIRE_MS = 48 * 60 * 60 * 1000
 
@@ -1164,18 +1175,16 @@ async def _check_local_password(self, user_id: str, password: str) -> Optional[s
             return None
         return user_id
 
-    async def validate_short_term_login_token_and_get_user_id(self, login_token: str):
-        auth_api = self.hs.get_auth()
-        user_id = None
+    async def validate_short_term_login_token(
+        self, login_token: str
+    ) -> LoginTokenAttributes:
         try:
-            macaroon = pymacaroons.Macaroon.deserialize(login_token)
-            user_id = auth_api.get_user_id_from_macaroon(macaroon)
-            auth_api.validate_macaroon(macaroon, "login", user_id)
+            res = self.macaroon_gen.verify_short_term_login_token(login_token)
         except Exception:
             raise AuthError(403, "Invalid token", errcode=Codes.FORBIDDEN)
 
-        await self.auth.check_auth_blocking(user_id)
-        return user_id
+        await self.auth.check_auth_blocking(res.user_id)
+        return res
 
     async def delete_access_token(self, access_token: str):
         """Invalidate a single access token
@@ -1397,6 +1406,7 @@ async def start_sso_ui_auth(self, request: SynapseRequest, session_id: str) -> s
     async def complete_sso_login(
         self,
         registered_user_id: str,
+        auth_provider_id: str,
         request: Request,
         client_redirect_url: str,
         extra_attributes: Optional[JsonDict] = None,
@@ -1406,6 +1416,9 @@ async def complete_sso_login(
 
         Args:
             registered_user_id: The registered user ID to complete SSO login for.
+            auth_provider_id: The id of the SSO Identity provider that was used for
+                login. This will be stored in the login token for future tracking in
+                prometheus metrics.
             request: The request to complete.
             client_redirect_url: The URL to which to redirect the user at the end of the
                 process.
@@ -1427,6 +1440,7 @@ async def complete_sso_login(
 
         self._complete_sso_login(
             registered_user_id,
+            auth_provider_id,
             request,
             client_redirect_url,
             extra_attributes,
@@ -1437,6 +1451,7 @@ async def complete_sso_login(
     def _complete_sso_login(
         self,
         registered_user_id: str,
+        auth_provider_id: str,
         request: Request,
         client_redirect_url: str,
         extra_attributes: Optional[JsonDict] = None,
@@ -1463,7 +1478,7 @@ def _complete_sso_login(
 
         # Create a login token
         login_token = self.macaroon_gen.generate_short_term_login_token(
-            registered_user_id
+            registered_user_id, auth_provider_id=auth_provider_id
         )
 
         # Append the login token to the original redirect URL (i.e. with its query
@@ -1569,15 +1584,48 @@ def generate_access_token(
         return macaroon.serialize()
 
     def generate_short_term_login_token(
-        self, user_id: str, duration_in_ms: int = (2 * 60 * 1000)
+        self,
+        user_id: str,
+        auth_provider_id: str,
+        duration_in_ms: int = (2 * 60 * 1000),
     ) -> str:
         macaroon = self._generate_base_macaroon(user_id)
         macaroon.add_first_party_caveat("type = login")
         now = self.hs.get_clock().time_msec()
         expiry = now + duration_in_ms
         macaroon.add_first_party_caveat("time < %d" % (expiry,))
+        macaroon.add_first_party_caveat("auth_provider_id = %s" % (auth_provider_id,))
         return macaroon.serialize()
 
+    def verify_short_term_login_token(self, token: str) -> LoginTokenAttributes:
+        """Verify a short-term-login macaroon
+
+        Checks that the given token is a valid, unexpired short-term-login token
+        minted by this server.
+
+        Args:
+            token: the login token to verify
+
+        Returns:
+            the user_id that this token is valid for
+
+        Raises:
+            MacaroonVerificationFailedException if the verification failed
+        """
+        macaroon = pymacaroons.Macaroon.deserialize(token)
+        user_id = get_value_from_macaroon(macaroon, "user_id")
+        auth_provider_id = get_value_from_macaroon(macaroon, "auth_provider_id", None)
+
+        v = pymacaroons.Verifier()
+        v.satisfy_exact("gen = 1")
+        v.satisfy_exact("type = login")
+        v.satisfy_general(lambda c: c.startswith("user_id = "))
+        v.satisfy_general(lambda c: c.startswith("auth_provider_id = "))
+        satisfy_expiry(v, self.hs.get_clock().time_msec)
+        v.verify(macaroon, self.hs.config.key.macaroon_secret_key)
+
+        return LoginTokenAttributes(user_id=user_id, auth_provider_id=auth_provider_id)
+
     def generate_delete_pusher_token(self, user_id: str) -> str:
         macaroon = self._generate_base_macaroon(user_id)
         macaroon.add_first_party_caveat("type = delete_pusher")

synapse/handlers/oidc_handler.py

@@ -42,6 +42,7 @@
 from synapse.types import JsonDict, UserID, map_username_to_mxid_localpart
 from synapse.util import json_decoder
 from synapse.util.caches.cached_call import RetryOnExceptionCachedCall
+from synapse.util.macaroons import get_value_from_macaroon, satisfy_expiry
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer
@@ -211,7 +212,7 @@ async def handle_oidc_callback(self, request: SynapseRequest) -> None:
             session_data = self._token_generator.verify_oidc_session_token(
                 session, state
             )
-        except (MacaroonDeserializationException, ValueError) as e:
+        except (MacaroonDeserializationException, KeyError) as e:
             logger.exception("Invalid session for OIDC callback")
             self._sso_handler.render_error(request, "invalid_session", str(e))
             return
@@ -1046,7 +1047,7 @@ def verify_oidc_session_token(
             The data extracted from the session cookie
 
         Raises:
-            ValueError if an expected caveat is missing from the macaroon.
+            KeyError if an expected caveat is missing from the macaroon.
         """
         macaroon = pymacaroons.Macaroon.deserialize(session)
 
@@ -1060,21 +1061,19 @@ def verify_oidc_session_token(
         # Sometimes there's a UI auth session ID, it seems to be OK to attempt
         # to always satisfy this.
         v.satisfy_general(lambda c: c.startswith("ui_auth_session_id = "))
-        v.satisfy_general(self._verify_expiry)
+        satisfy_expiry(v, self._clock.time_msec)
 
         v.verify(macaroon, self._macaroon_secret_key)
 
         # Extract the session data from the token.
-        nonce = self._get_value_from_macaroon(macaroon, "nonce")
-        idp_id = self._get_value_from_macaroon(macaroon, "idp_id")
-        client_redirect_url = self._get_value_from_macaroon(
-            macaroon, "client_redirect_url"
-        )
+        nonce = get_value_from_macaroon(macaroon, "nonce")
+        idp_id = get_value_from_macaroon(macaroon, "idp_id")
+        client_redirect_url = get_value_from_macaroon(macaroon, "client_redirect_url")
         try:
-            ui_auth_session_id = self._get_value_from_macaroon(
+            ui_auth_session_id = get_value_from_macaroon(
                 macaroon, "ui_auth_session_id"
             )  # type: Optional[str]
-        except ValueError:
+        except KeyError:
             ui_auth_session_id = None
 
         return OidcSessionData(
@@ -1084,33 +1083,6 @@ def verify_oidc_session_token(
             ui_auth_session_id=ui_auth_session_id,
         )
 
-    def _get_value_from_macaroon(self, macaroon: pymacaroons.Macaroon, key: str) -> str:
-        """Extracts a caveat value from a macaroon token.
-
-        Args:
-            macaroon: the token
-            key: the key of the caveat to extract
-
-        Returns:
-            The extracted value
-
-        Raises:
-            ValueError: if the caveat was not in the macaroon
-        """
-        prefix = key + " = "
-        for caveat in macaroon.caveats:
-            if caveat.caveat_id.startswith(prefix):
-                return caveat.caveat_id[len(prefix) :]
-        raise ValueError("No %s caveat in macaroon" % (key,))
-
-    def _verify_expiry(self, caveat: str) -> bool:
-        prefix = "time < "
-        if not caveat.startswith(prefix):
-            return False
-        expiry = int(caveat[len(prefix) :])
-        now = self._clock.time_msec()
-        return now < expiry
-
 
 @attr.s(frozen=True, slots=True)
 class OidcSessionData:

synapse/handlers/sso.py

@@ -456,6 +456,7 @@ async def complete_sso_login_request(
 
         await self._auth_handler.complete_sso_login(
             user_id,
+            auth_provider_id,
             request,
             client_redirect_url,
             extra_login_attributes,
@@ -886,6 +887,7 @@ async def register_sso_user(self, request: Request, session_id: str) -> None:
 
         await self._auth_handler.complete_sso_login(
             user_id,
+            session.auth_provider_id,
             request,
             session.client_redirect_url,
             session.extra_login_attributes,