""" Copyright (c) 2018 Noderabbit Inc., d.b.a. Appsembler All rights reserved. MIT License Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. See https://nicksnettravels.builttoroam.com/post/2017/01/24/Verifying-Azure-Active-Directory-JWT-Tokens.aspx for verifying JWT tokens. """ import json from cryptography.hazmat.primitives import serialization from jwt import DecodeError, ExpiredSignatureError, get_unverified_header from jwt import decode as jwt_decode from jwt.algorithms import RSAAlgorithm from ..exceptions import AuthException, AuthTokenError from .azuread import AzureADOAuth2 class AzureADB2COAuth2(AzureADOAuth2): name = "azuread-b2c-oauth2" BASE_URL = "https://{authority_host}/{tenant_name}.onmicrosoft.com" AUTHORIZATION_URL = "{base_url}/oauth2/v2.0/authorize" OPENID_CONFIGURATION_URL = ( "{base_url}/v2.0/.well-known/openid-configuration?p={policy}" ) ACCESS_TOKEN_URL = "{base_url}/oauth2/v2.0/token?p={policy}" JWKS_URL = "{base_url}/discovery/v2.0/keys?p={policy}" DEFAULT_SCOPE = ["openid", "email"] EXTRA_DATA = [ ("access_token", "access_token"), ("id_token", "id_token"), ("refresh_token", "refresh_token"), ("id_token_expires_in", "expires"), ("exp", "expires_on"), ("not_before", "not_before"), ("given_name", "first_name"), ("family_name", "last_name"), ("tfp", "policy"), ("token_type", "token_type"), ] @property def authority_host(self): return self.setting("AUTHORITY_HOST", f"{self.tenant_name}.b2clogin.com") @property def tenant_name(self): return self.setting("TENANT_NAME") @property def policy(self): policy = self.setting("POLICY") if not policy or not policy.lower().startswith("b2c_"): raise AuthException( self, "SOCIAL_AUTH_AZUREAD_B2C_OAUTH2_POLICY is " "required and should start with `b2c_`", ) return policy @property def base_url(self): return self.BASE_URL.format( tenant_name=self.tenant_name, authority_host=self.authority_host ) def openid_configuration_url(self): return self.OPENID_CONFIGURATION_URL.format( base_url=self.base_url, policy=self.policy ) def authorization_url(self): # Policy is required, but added later by `auth_extra_arguments()` return self.AUTHORIZATION_URL.format(base_url=self.base_url) def access_token_url(self): return self.ACCESS_TOKEN_URL.format(base_url=self.base_url, policy=self.policy) def jwks_url(self): return self.JWKS_URL.format(base_url=self.base_url, policy=self.policy) def request_access_token(self, *args, **kwargs): """ This is probably a hack, but otherwise AzureADOAuth2 expects `access_token`. However, B2C backends provides `id_token`. """ response = super().request_access_token(*args, **kwargs) if "access_token" not in response: response["access_token"] = response["id_token"] return response def auth_extra_arguments(self): """ Return extra arguments needed on auth process. The defaults can be overridden by GET parameters. """ extra_arguments = super().auth_extra_arguments() extra_arguments["p"] = self.policy or self.data.get("p") return extra_arguments def jwt_key_to_pem(self, key_json_dict): """ Builds a PEM formatted key string from a JWT public key dict. """ pub_key = RSAAlgorithm.from_jwk(json.dumps(key_json_dict)) # TODO: clarify the types of this; JWKs can apparently include both public and private, # but this code assumes public. return pub_key.public_bytes( # type: ignore[reportAttributeAccessIssue] encoding=serialization.Encoding.PEM, format=serialization.PublicFormat.SubjectPublicKeyInfo, ) def get_user_id(self, details, response): """Use subject (sub) claim as unique id.""" return response.get("sub") def get_user_details(self, response): """ Email address is returned on a different attribute for AzureAD B2C backends. """ details = super().get_user_details(response) if not details["email"] and response.get("emails"): details["email"] = response["emails"] if isinstance(details.get("email"), (list, tuple)): details["email"] = details["email"][0] return details def get_public_key(self, kid): """ Retrieve JWT keys from the URL. """ resp = self.request(self.jwks_url(), method="GET") resp.raise_for_status() # find the proper key for the kid for key in resp.json()["keys"]: if key["kid"] == kid: return self.jwt_key_to_pem(key) raise DecodeError(f"Cannot find kid={kid}") def user_data(self, access_token, *args, **kwargs): response = kwargs.get("response") id_token = response.get("id_token") # `kid` is short for key id kid = get_unverified_header(id_token)["kid"] key = self.get_public_key(kid) try: return jwt_decode( id_token, key=key, algorithms=["RS256"], audience=self.setting("KEY"), leeway=self.setting("JWT_LEEWAY", default=0), ) except (DecodeError, ExpiredSignatureError) as error: raise AuthTokenError(self, error)