Store an IdP ID in the OIDC session (#9109)

Again in preparation for handling more than one OIDC provider, add a new caveat to the macaroon used as an OIDC session cookie, which remembers which OIDC provider we are talking to. In future, when we get a callback, we'll need it to make sure we talk to the right IdP.

As part of this, I'm adding an idp_id and idp_name field to the OIDC configuration object. They aren't yet documented, and we'll just use the old values by default.
This commit is contained in:
Richard van der Hoff 2021-01-15 13:22:12 +00:00 committed by GitHub
parent 20af310889
commit 4575ad0b1e
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4 changed files with 42 additions and 10 deletions

1
changelog.d/9109.feature Normal file
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@ -0,0 +1 @@
Add support for multiple SSO Identity Providers.

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@ -1,6 +1,6 @@
# -*- coding: utf-8 -*-
# Copyright 2020 Quentin Gliech
# Copyright 2020 The Matrix.org Foundation C.I.C.
# Copyright 2020-2021 The Matrix.org Foundation C.I.C.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
@ -14,6 +14,7 @@
# See the License for the specific language governing permissions and
# limitations under the License.
import string
from typing import Optional, Type
import attr
@ -38,7 +39,7 @@ class OIDCConfig(Config):
oidc_config = config.get("oidc_config")
if oidc_config and oidc_config.get("enabled", False):
validate_config(OIDC_PROVIDER_CONFIG_SCHEMA, oidc_config, "oidc_config")
validate_config(OIDC_PROVIDER_CONFIG_SCHEMA, oidc_config, ("oidc_config",))
self.oidc_provider = _parse_oidc_config_dict(oidc_config)
if not self.oidc_provider:
@ -205,6 +206,8 @@ OIDC_PROVIDER_CONFIG_SCHEMA = {
"type": "object",
"required": ["issuer", "client_id", "client_secret"],
"properties": {
"idp_id": {"type": "string", "minLength": 1, "maxLength": 128},
"idp_name": {"type": "string"},
"discover": {"type": "boolean"},
"issuer": {"type": "string"},
"client_id": {"type": "string"},
@ -277,7 +280,17 @@ def _parse_oidc_config_dict(oidc_config: JsonDict) -> "OidcProviderConfig":
"methods: %s" % (", ".join(missing_methods),)
)
# MSC2858 will appy certain limits in what can be used as an IdP id, so let's
# enforce those limits now.
idp_id = oidc_config.get("idp_id", "oidc")
valid_idp_chars = set(string.ascii_letters + string.digits + "-._~")
if any(c not in valid_idp_chars for c in idp_id):
raise ConfigError('idp_id may only contain A-Z, a-z, 0-9, "-", ".", "_", "~"')
return OidcProviderConfig(
idp_id=idp_id,
idp_name=oidc_config.get("idp_name", "OIDC"),
discover=oidc_config.get("discover", True),
issuer=oidc_config["issuer"],
client_id=oidc_config["client_id"],
@ -296,8 +309,15 @@ def _parse_oidc_config_dict(oidc_config: JsonDict) -> "OidcProviderConfig":
)
@attr.s
@attr.s(slots=True, frozen=True)
class OidcProviderConfig:
# a unique identifier for this identity provider. Used in the 'user_external_ids'
# table, as well as the query/path parameter used in the login protocol.
idp_id = attr.ib(type=str)
# user-facing name for this identity provider.
idp_name = attr.ib(type=str)
# whether the OIDC discovery mechanism is used to discover endpoints
discover = attr.ib(type=bool)

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@ -175,7 +175,7 @@ class OidcHandler:
session_data = self._token_generator.verify_oidc_session_token(
session, state
)
except MacaroonDeserializationException as e:
except (MacaroonDeserializationException, ValueError) as e:
logger.exception("Invalid session")
self._sso_handler.render_error(request, "invalid_session", str(e))
return
@ -253,10 +253,10 @@ class OidcProvider:
self._server_name = hs.config.server_name # type: str
# identifier for the external_ids table
self.idp_id = "oidc"
self.idp_id = provider.idp_id
# user-facing name of this auth provider
self.idp_name = "OIDC"
self.idp_name = provider.idp_name
self._sso_handler = hs.get_sso_handler()
@ -656,6 +656,7 @@ class OidcProvider:
cookie = self._token_generator.generate_oidc_session_token(
state=state,
session_data=OidcSessionData(
idp_id=self.idp_id,
nonce=nonce,
client_redirect_url=client_redirect_url.decode(),
ui_auth_session_id=ui_auth_session_id,
@ -924,6 +925,7 @@ class OidcSessionTokenGenerator:
macaroon.add_first_party_caveat("gen = 1")
macaroon.add_first_party_caveat("type = session")
macaroon.add_first_party_caveat("state = %s" % (state,))
macaroon.add_first_party_caveat("idp_id = %s" % (session_data.idp_id,))
macaroon.add_first_party_caveat("nonce = %s" % (session_data.nonce,))
macaroon.add_first_party_caveat(
"client_redirect_url = %s" % (session_data.client_redirect_url,)
@ -952,6 +954,9 @@ class OidcSessionTokenGenerator:
Returns:
The data extracted from the session cookie
Raises:
ValueError if an expected caveat is missing from the macaroon.
"""
macaroon = pymacaroons.Macaroon.deserialize(session)
@ -960,6 +965,7 @@ class OidcSessionTokenGenerator:
v.satisfy_exact("type = session")
v.satisfy_exact("state = %s" % (state,))
v.satisfy_general(lambda c: c.startswith("nonce = "))
v.satisfy_general(lambda c: c.startswith("idp_id = "))
v.satisfy_general(lambda c: c.startswith("client_redirect_url = "))
# Sometimes there's a UI auth session ID, it seems to be OK to attempt
# to always satisfy this.
@ -968,9 +974,9 @@ class OidcSessionTokenGenerator:
v.verify(macaroon, self._macaroon_secret_key)
# Extract the `nonce`, `client_redirect_url`, and maybe the
# `ui_auth_session_id` from the token.
# 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"
)
@ -983,6 +989,7 @@ class OidcSessionTokenGenerator:
return OidcSessionData(
nonce=nonce,
idp_id=idp_id,
client_redirect_url=client_redirect_url,
ui_auth_session_id=ui_auth_session_id,
)
@ -998,7 +1005,7 @@ class OidcSessionTokenGenerator:
The extracted value
Raises:
Exception: if the caveat was not in the macaroon
ValueError: if the caveat was not in the macaroon
"""
prefix = key + " = "
for caveat in macaroon.caveats:
@ -1019,6 +1026,9 @@ class OidcSessionTokenGenerator:
class OidcSessionData:
"""The attributes which are stored in a OIDC session cookie"""
# the Identity Provider being used
idp_id = attr.ib(type=str)
# The `nonce` parameter passed to the OIDC provider.
nonce = attr.ib(type=str)

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@ -848,6 +848,7 @@ class OidcHandlerTestCase(HomeserverTestCase):
return self.handler._token_generator.generate_oidc_session_token(
state=state,
session_data=OidcSessionData(
idp_id="oidc",
nonce=nonce,
client_redirect_url=client_redirect_url,
ui_auth_session_id=ui_auth_session_id,
@ -990,7 +991,7 @@ async def _make_callback_with_userinfo(
session = handler._token_generator.generate_oidc_session_token(
state=state,
session_data=OidcSessionData(
nonce="nonce", client_redirect_url=client_redirect_url,
idp_id="oidc", nonce="nonce", client_redirect_url=client_redirect_url,
),
)
request = _build_callback_request("code", state, session)