329 lines
13 KiB
Python
329 lines
13 KiB
Python
import time
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import json
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import logging
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import urlparse
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import jwt
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from cachetools.func import lru_cache
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from cachetools.ttl import TTLCache
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from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives.serialization import load_der_public_key
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from jwkest.jwk import KEYS
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from oauth.base import (OAuthService, OAuthExchangeCodeException, OAuthGetUserInfoException,
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OAuthEndpoint)
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from oauth.login import OAuthLoginException
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from util.security.jwtutil import decode, InvalidTokenError
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logger = logging.getLogger(__name__)
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OIDC_WELLKNOWN = ".well-known/openid-configuration"
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PUBLIC_KEY_CACHE_TTL = 3600 # 1 hour
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ALLOWED_ALGORITHMS = ['RS256']
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JWT_CLOCK_SKEW_SECONDS = 30
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class DiscoveryFailureException(Exception):
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""" Exception raised when OIDC discovery fails. """
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pass
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class PublicKeyLoadException(Exception):
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""" Exception raised if loading the OIDC public key fails. """
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pass
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class OIDCLoginService(OAuthService):
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""" Defines a generic service for all OpenID-connect compatible login services. """
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def __init__(self, config, key_name, client=None):
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super(OIDCLoginService, self).__init__(config, key_name)
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self._id = key_name[0:key_name.find('_')].lower()
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self._http_client = client or config.get('HTTPCLIENT')
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self._mailing = config.get('FEATURE_MAILING', False)
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self._public_key_cache = _PublicKeyCache(self, 1, PUBLIC_KEY_CACHE_TTL)
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def service_id(self):
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return self._id
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def service_name(self):
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return self.config.get('SERVICE_NAME', self.service_id())
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def get_icon(self):
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return self.config.get('SERVICE_ICON', 'fa-user-circle')
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def get_login_scopes(self):
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default_scopes = ['openid']
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if self.user_endpoint() is not None:
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default_scopes.append('profile')
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if self._mailing:
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default_scopes.append('email')
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supported_scopes = self._oidc_config().get('scopes_supported', default_scopes)
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login_scopes = self.config.get('LOGIN_SCOPES') or supported_scopes
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return list(set(login_scopes) & set(supported_scopes))
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def authorize_endpoint(self):
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return self._get_endpoint('authorization_endpoint').with_param('response_type', 'code')
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def token_endpoint(self):
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return self._get_endpoint('token_endpoint')
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def user_endpoint(self):
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return self._get_endpoint('userinfo_endpoint')
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def _get_endpoint(self, endpoint_key, **kwargs):
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""" Returns the OIDC endpoint with the given key found in the OIDC discovery
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document, with the given kwargs added as query parameters. Additionally,
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any defined parameters found in the OIDC configuration block are also
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added.
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"""
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endpoint = self._oidc_config().get(endpoint_key, '')
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if not endpoint:
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return None
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(scheme, netloc, path, query, fragment) = urlparse.urlsplit(endpoint)
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# Add the query parameters from the kwargs and the config.
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custom_parameters = self.config.get('OIDC_ENDPOINT_CUSTOM_PARAMS', {}).get(endpoint_key, {})
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query_params = urlparse.parse_qs(query, keep_blank_values=True)
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query_params.update(kwargs)
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query_params.update(custom_parameters)
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return OAuthEndpoint(urlparse.urlunsplit((scheme, netloc, path, {}, fragment)), query_params)
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def validate(self):
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return bool(self.get_login_scopes())
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def validate_client_id_and_secret(self, http_client, url_scheme_and_hostname):
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# TODO: find a way to verify client secret too.
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check_auth_url = http_client.get(self.get_auth_url(url_scheme_and_hostname, '', '', []))
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if check_auth_url.status_code // 100 != 2:
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raise Exception('Got non-200 status code for authorization endpoint')
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def requires_form_encoding(self):
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return True
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def get_public_config(self):
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return {
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'CLIENT_ID': self.client_id(),
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'OIDC': True,
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}
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def exchange_code_for_tokens(self, app_config, http_client, code, redirect_suffix):
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# Exchange the code for the access token and id_token
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try:
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json_data = self.exchange_code(app_config, http_client, code,
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redirect_suffix=redirect_suffix,
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form_encode=self.requires_form_encoding())
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except OAuthExchangeCodeException as oce:
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raise OAuthLoginException(str(oce))
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# Make sure we received both.
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access_token = json_data.get('access_token', None)
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if access_token is None:
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logger.debug('Missing access_token in response: %s', json_data)
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raise OAuthLoginException('Missing `access_token` in OIDC response')
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id_token = json_data.get('id_token', None)
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if id_token is None:
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logger.debug('Missing id_token in response: %s', json_data)
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raise OAuthLoginException('Missing `id_token` in OIDC response')
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return id_token, access_token
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def exchange_code_for_login(self, app_config, http_client, code, redirect_suffix):
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# Exchange the code for the access token and id_token
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id_token, access_token = self.exchange_code_for_tokens(app_config, http_client, code,
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redirect_suffix)
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# Decode the id_token.
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try:
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decoded_id_token = self.decode_user_jwt(id_token)
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except InvalidTokenError as ite:
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logger.exception('Got invalid token error on OIDC decode: %s', ite)
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raise OAuthLoginException('Could not decode OIDC token')
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except PublicKeyLoadException as pke:
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logger.exception('Could not load public key during OIDC decode: %s', pke)
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raise OAuthLoginException('Could find public OIDC key')
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# If there is a user endpoint, use it to retrieve the user's information. Otherwise, we use
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# the decoded ID token.
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if self.user_endpoint():
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# Retrieve the user information.
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try:
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user_info = self.get_user_info(http_client, access_token)
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except OAuthGetUserInfoException as oge:
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raise OAuthLoginException(str(oge))
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else:
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user_info = decoded_id_token
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# Verify subs.
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if user_info['sub'] != decoded_id_token['sub']:
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logger.debug('Mismatch in `sub` returned by OIDC user info endpoint: %s vs %s',
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user_info['sub'], decoded_id_token['sub'])
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raise OAuthLoginException('Mismatch in `sub` returned by OIDC user info endpoint')
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# Check if we have a verified email address.
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if self.config.get('VERIFIED_EMAIL_CLAIM_NAME'):
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email_address = user_info.get(self.config['VERIFIED_EMAIL_CLAIM_NAME'])
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else:
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email_address = user_info.get('email') if user_info.get('email_verified') else None
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logger.debug('Found e-mail address `%s` for sub `%s`', email_address, user_info['sub'])
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if self._mailing:
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if email_address is None:
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raise OAuthLoginException('A verified email address is required to login with this service')
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# Check for a preferred username.
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if self.config.get('PREFERRED_USERNAME_CLAIM_NAME'):
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lusername = user_info.get(self.config['PREFERRED_USERNAME_CLAIM_NAME'])
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else:
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lusername = user_info.get('preferred_username')
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if lusername is None:
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# Note: Active Directory provides `unique_name` and `upn`.
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# https://docs.microsoft.com/en-us/azure/active-directory/develop/v1-id-and-access-tokens
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lusername = user_info.get('unique_name', user_info.get('upn'))
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if lusername is None:
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lusername = user_info['sub']
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if lusername.find('@') >= 0:
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lusername = lusername[0:lusername.find('@')]
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return decoded_id_token['sub'], lusername, email_address
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@property
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def _issuer(self):
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# Read the issuer from the OIDC config, falling back to the configured OIDC server.
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issuer = self._oidc_config().get('issuer', self.config['OIDC_SERVER'])
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# If specified, use the overridden OIDC issuer.
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return self.config.get('OIDC_ISSUER', issuer)
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@lru_cache(maxsize=1)
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def _oidc_config(self):
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if self.config.get('OIDC_SERVER'):
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return self._load_oidc_config_via_discovery(self.config.get('DEBUGGING', False))
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else:
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return {}
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def _load_oidc_config_via_discovery(self, is_debugging):
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""" Attempts to load the OIDC config via the OIDC discovery mechanism. If is_debugging is True,
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non-secure connections are alllowed. Raises an DiscoveryFailureException on failure.
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"""
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oidc_server = self.config['OIDC_SERVER']
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if not oidc_server.startswith('https://') and not is_debugging:
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raise DiscoveryFailureException('OIDC server must be accessed over SSL')
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discovery_url = urlparse.urljoin(oidc_server, OIDC_WELLKNOWN)
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discovery = self._http_client.get(discovery_url, timeout=5, verify=is_debugging is False)
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if discovery.status_code // 100 != 2:
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logger.debug('Got %s response for OIDC discovery: %s', discovery.status_code, discovery.text)
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raise DiscoveryFailureException("Could not load OIDC discovery information")
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try:
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return json.loads(discovery.text)
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except ValueError:
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logger.exception('Could not parse OIDC discovery for url: %s', discovery_url)
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raise DiscoveryFailureException("Could not parse OIDC discovery information")
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def decode_user_jwt(self, token):
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""" Decodes the given JWT under the given provider and returns it. Raises an InvalidTokenError
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exception on an invalid token or a PublicKeyLoadException if the public key could not be
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loaded for decoding.
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"""
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# Find the key to use.
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headers = jwt.get_unverified_header(token)
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kid = headers.get('kid', None)
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if kid is None:
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raise InvalidTokenError('Missing `kid` header')
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logger.debug('Using key `%s`, attempting to decode token `%s` with aud `%s` and iss `%s`',
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kid, token, self.client_id(), self._issuer)
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try:
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return decode(token, self._get_public_key(kid), algorithms=ALLOWED_ALGORITHMS,
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audience=self.client_id(),
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issuer=self._issuer,
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leeway=JWT_CLOCK_SKEW_SECONDS,
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options=dict(require_nbf=False))
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except InvalidTokenError as ite:
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logger.warning('Could not decode token `%s` for OIDC: %s. Will attempt again after ' +
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'retrieving public keys.', token, ite)
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# Public key may have expired. Try to retrieve an updated public key and use it to decode.
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try:
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return decode(token, self._get_public_key(kid, force_refresh=True),
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algorithms=ALLOWED_ALGORITHMS,
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audience=self.client_id(),
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issuer=self._issuer,
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leeway=JWT_CLOCK_SKEW_SECONDS,
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options=dict(require_nbf=False))
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except InvalidTokenError as ite:
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logger.warning('Could not decode token `%s` for OIDC: %s. Attempted again after ' +
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'retrieving public keys.', token, ite)
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# Decode again with verify=False, and log the decoded token to allow for easier debugging.
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nonverified = decode(token, self._get_public_key(kid, force_refresh=True),
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algorithms=ALLOWED_ALGORITHMS,
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audience=self.client_id(),
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issuer=self._issuer,
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leeway=JWT_CLOCK_SKEW_SECONDS,
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options=dict(require_nbf=False, verify=False))
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logger.debug('Got an error when trying to verify OIDC JWT: %s', nonverified)
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raise ite
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def _get_public_key(self, kid, force_refresh=False):
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""" Retrieves the public key for this handler with the given kid. Raises a
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PublicKeyLoadException on failure. """
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# If force_refresh is true, we expire all the items in the cache by setting the time to
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# the current time + the expiration TTL.
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if force_refresh:
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self._public_key_cache.expire(time=time.time() + PUBLIC_KEY_CACHE_TTL)
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# Retrieve the public key from the cache. If the cache does not contain the public key,
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# it will internally call _load_public_key to retrieve it and then save it.
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return self._public_key_cache[kid]
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class _PublicKeyCache(TTLCache):
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def __init__(self, login_service, *args, **kwargs):
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super(_PublicKeyCache, self).__init__(*args, **kwargs)
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self._login_service = login_service
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def __missing__(self, kid):
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""" Loads the public key for this handler from the OIDC service. Raises PublicKeyLoadException
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on failure.
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"""
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keys_url = self._login_service._oidc_config()['jwks_uri']
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# Load the keys.
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try:
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keys = KEYS()
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keys.load_from_url(keys_url, verify=not self._login_service.config.get('DEBUGGING', False))
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except Exception as ex:
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logger.exception('Exception loading public key')
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raise PublicKeyLoadException(str(ex))
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# Find the matching key.
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keys_found = keys.by_kid(kid)
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if len(keys_found) == 0:
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raise PublicKeyLoadException('Public key %s not found' % kid)
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rsa_keys = [key for key in keys_found if key.kty == 'RSA']
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if len(rsa_keys) == 0:
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raise PublicKeyLoadException('No RSA form of public key %s not found' % kid)
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matching_key = rsa_keys[0]
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matching_key.deserialize()
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# Reload the key so that we can give a key *instance* to PyJWT to work around its weird parsing
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# issues.
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final_key = load_der_public_key(matching_key.key.exportKey('DER'), backend=default_backend())
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self[kid] = final_key
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return final_key
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