/
auth_token.py
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/
auth_token.py
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2010-2012 OpenStack LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
TOKEN-BASED AUTH MIDDLEWARE
This WSGI component:
* Verifies that incoming client requests have valid tokens by validating
tokens with the auth service.
* Rejects unauthenticated requests UNLESS it is in 'delay_auth_decision'
mode, which means the final decision is delegated to the downstream WSGI
component (usually the OpenStack service)
* Collects and forwards identity information based on a valid token
such as user name, tenant, etc
Refer to: http://keystone.openstack.org/middleware_architecture.html
HEADERS
-------
* Headers starting with HTTP\_ is a standard http header
* Headers starting with HTTP_X is an extended http header
Coming in from initial call from client or customer
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
HTTP_X_AUTH_TOKEN
The client token being passed in.
HTTP_X_STORAGE_TOKEN
The client token being passed in (legacy Rackspace use) to support
swift/cloud files
Used for communication between components
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
WWW-Authenticate
HTTP header returned to a user indicating which endpoint to use
to retrieve a new token
What we add to the request for use by the OpenStack service
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
HTTP_X_IDENTITY_STATUS
'Confirmed' or 'Invalid'
The underlying service will only see a value of 'Invalid' if the Middleware
is configured to run in 'delay_auth_decision' mode
HTTP_X_TENANT_ID
Identity service managed unique identifier, string
HTTP_X_TENANT_NAME
Unique tenant identifier, string
HTTP_X_USER_ID
Identity-service managed unique identifier, string
HTTP_X_USER_NAME
Unique user identifier, string
HTTP_X_ROLES
Comma delimited list of case-sensitive Roles
HTTP_X_TENANT
*Deprecated* in favor of HTTP_X_TENANT_ID and HTTP_X_TENANT_NAME
Keystone-assigned unique identifier, deprecated
HTTP_X_USER
*Deprecated* in favor of HTTP_X_USER_ID and HTTP_X_USER_NAME
Unique user name, string
HTTP_X_ROLE
*Deprecated* in favor of HTTP_X_ROLES
This is being renamed, and the new header contains the same data.
"""
import httplib
import json
import logging
import time
import webob
import webob.exc
logger = logging.getLogger('keystone.middleware.auth_token')
class InvalidUserToken(Exception):
pass
class ServiceError(Exception):
pass
class AuthProtocol(object):
"""Auth Middleware that handles authenticating client calls."""
def __init__(self, app, conf):
logger.info('Starting keystone auth_token middleware')
self.conf = conf
self.app = app
# delay_auth_decision means we still allow unauthenticated requests
# through and we let the downstream service make the final decision
self.delay_auth_decision = int(conf.get('delay_auth_decision', 0))
# where to find the auth service (we use this to validate tokens)
self.auth_host = conf.get('auth_host')
self.auth_port = int(conf.get('auth_port', 35357))
auth_protocol = conf.get('auth_protocol', 'https')
if auth_protocol == 'http':
self.http_client_class = httplib.HTTPConnection
else:
self.http_client_class = httplib.HTTPSConnection
default_auth_uri = '%s://%s:%s' % (auth_protocol,
self.auth_host,
self.auth_port)
self.auth_uri = conf.get('auth_uri', default_auth_uri)
# Credentials used to verify this component with the Auth service since
# validating tokens is a privileged call
self.admin_token = conf.get('admin_token')
self.admin_user = conf.get('admin_user')
self.admin_password = conf.get('admin_password')
self.admin_tenant_name = conf.get('admin_tenant_name', 'admin')
# Token caching via memcache
self._cache = None
self._iso8601 = None
memcache_servers = conf.get('memcache_servers')
# By default the token will be cached for 5 minutes
self.token_cache_time = conf.get('token_cache_time', 300)
if memcache_servers:
try:
import memcache
import iso8601
logger.info('Using memcache for caching token')
self._cache = memcache.Client(memcache_servers.split(','))
self._iso8601 = iso8601
except NameError as e:
logger.warn('disabled caching due to missing libraries %s', e)
def __call__(self, env, start_response):
"""Handle incoming request.
Authenticate send downstream on success. Reject request if
we can't authenticate.
"""
logger.debug('Authenticating user token')
try:
self._remove_auth_headers(env)
user_token = self._get_user_token_from_header(env)
token_info = self._validate_user_token(user_token)
user_headers = self._build_user_headers(token_info)
self._add_headers(env, user_headers)
return self.app(env, start_response)
except InvalidUserToken:
if self.delay_auth_decision:
logger.info('Invalid user token - deferring reject downstream')
self._add_headers(env, {'X-Identity-Status': 'Invalid'})
return self.app(env, start_response)
else:
logger.info('Invalid user token - rejecting request')
return self._reject_request(env, start_response)
except ServiceError, e:
logger.critical('Unable to obtain admin token: %s' % e)
resp = webob.exc.HTTPServiceUnavailable()
return resp(env, start_response)
def _remove_auth_headers(self, env):
"""Remove headers so a user can't fake authentication.
:param env: wsgi request environment
"""
auth_headers = (
'X-Identity-Status',
'X-Tenant-Id',
'X-Tenant-Name',
'X-User-Id',
'X-User-Name',
'X-Roles',
# Deprecated
'X-User',
'X-Tenant',
'X-Role',
)
logger.debug('Removing headers from request environment: %s' %
','.join(auth_headers))
self._remove_headers(env, auth_headers)
def _get_user_token_from_header(self, env):
"""Get token id from request.
:param env: wsgi request environment
:return token id
:raises InvalidUserToken if no token is provided in request
"""
token = self._get_header(env, 'X-Auth-Token',
self._get_header(env, 'X-Storage-Token'))
if token:
return token
else:
raise InvalidUserToken('Unable to find token in headers')
def _reject_request(self, env, start_response):
"""Redirect client to auth server.
:param env: wsgi request environment
:param start_response: wsgi response callback
:returns HTTPUnauthorized http response
"""
headers = [('WWW-Authenticate', 'Keystone uri=\'%s\'' % self.auth_uri)]
resp = webob.exc.HTTPUnauthorized('Authentication required', headers)
return resp(env, start_response)
def get_admin_token(self):
"""Return admin token, possibly fetching a new one.
:return admin token id
:raise ServiceError when unable to retrieve token from keystone
"""
if not self.admin_token:
self.admin_token = self._request_admin_token()
return self.admin_token
def _get_http_connection(self):
return self.http_client_class(self.auth_host, self.auth_port)
def _json_request(self, method, path, body=None, additional_headers=None):
"""HTTP request helper used to make json requests.
:param method: http method
:param path: relative request url
:param body: dict to encode to json as request body. Optional.
:param additional_headers: dict of additional headers to send with
http request. Optional.
:return (http response object, response body parsed as json)
:raise ServerError when unable to communicate with keystone
"""
conn = self._get_http_connection()
kwargs = {
'headers': {
'Content-type': 'application/json',
'Accept': 'application/json',
},
}
if additional_headers:
kwargs['headers'].update(additional_headers)
if body:
kwargs['body'] = json.dumps(body)
try:
conn.request(method, path, **kwargs)
response = conn.getresponse()
body = response.read()
except Exception, e:
logger.error('HTTP connection exception: %s' % e)
raise ServiceError('Unable to communicate with keystone')
finally:
conn.close()
try:
data = json.loads(body)
except ValueError:
logger.debug('Keystone did not return json-encoded body')
data = {}
return response, data
def _request_admin_token(self):
"""Retrieve new token as admin user from keystone.
:return token id upon success
:raises ServerError when unable to communicate with keystone
"""
params = {
'auth': {
'passwordCredentials': {
'username': self.admin_user,
'password': self.admin_password,
},
'tenantName': self.admin_tenant_name,
}
}
response, data = self._json_request('POST',
'/v2.0/tokens',
body=params)
try:
token = data['access']['token']['id']
assert token
return token
except (AssertionError, KeyError):
raise ServiceError('invalid json response')
def _validate_user_token(self, user_token, retry=True):
"""Authenticate user token with keystone.
:param user_token: user's token id
:param retry: flag that forces the middleware to retry
user authentication when an indeterminate
response is received. Optional.
:return token object received from keystone on success
:raise InvalidUserToken if token is rejected
:raise ServiceError if unable to authenticate token
"""
cached = self._cache_get(user_token)
if cached:
return cached
headers = {'X-Auth-Token': self.get_admin_token()}
response, data = self._json_request('GET',
'/v2.0/tokens/%s' % user_token,
additional_headers=headers)
if response.status == 200:
self._cache_put(user_token, data)
return data
if response.status == 404:
# FIXME(ja): I'm assuming the 404 status means that user_token is
# invalid - not that the admin_token is invalid
self._cache_store_invalid(user_token)
raise InvalidUserToken('Token authorization failed')
if response.status == 401:
logger.info('Keystone rejected admin token, resetting')
self.admin_token = None
else:
logger.error('Bad response code while validating token: %s' %
response.status)
if retry:
logger.info('Retrying validation')
return self._validate_user_token(user_token, False)
else:
raise InvalidUserToken()
def _build_user_headers(self, token_info):
"""Convert token object into headers.
Build headers that represent authenticated user:
* X_IDENTITY_STATUS: Confirmed or Invalid
* X_TENANT_ID: id of tenant if tenant is present
* X_TENANT_NAME: name of tenant if tenant is present
* X_USER_ID: id of user
* X_USER_NAME: name of user
* X_ROLES: list of roles
Additional (deprecated) headers include:
* X_USER: name of user
* X_TENANT: For legacy compatibility before we had ID and Name
* X_ROLE: list of roles
:param token_info: token object returned by keystone on authentication
:raise InvalidUserToken when unable to parse token object
"""
user = token_info['access']['user']
token = token_info['access']['token']
roles = ','.join([role['name'] for role in user.get('roles', [])])
def get_tenant_info():
"""Returns a (tenant_id, tenant_name) tuple from context."""
def essex():
"""Essex puts the tenant ID and name on the token."""
return (token['tenant']['id'], token['tenant']['name'])
def pre_diablo():
"""Pre-diablo, Keystone only provided tenantId."""
return (token['tenantId'], token['tenantId'])
def default_tenant():
"""Assume the user's default tenant."""
return (user['tenantId'], user['tenantName'])
for method in [essex, pre_diablo, default_tenant]:
try:
return method()
except KeyError:
pass
raise InvalidUserToken('Unable to determine tenancy.')
tenant_id, tenant_name = get_tenant_info()
user_id = user['id']
user_name = user['username']
return {
'X-Identity-Status': 'Confirmed',
'X-Tenant-Id': tenant_id,
'X-Tenant-Name': tenant_name,
'X-User-Id': user_id,
'X-User-Name': user_name,
'X-Roles': roles,
# Deprecated
'X-User': user_name,
'X-Tenant': tenant_name,
'X-Role': roles,
}
def _header_to_env_var(self, key):
"""Convert header to wsgi env variable.
:param key: http header name (ex. 'X-Auth-Token')
:return wsgi env variable name (ex. 'HTTP_X_AUTH_TOKEN')
"""
return 'HTTP_%s' % key.replace('-', '_').upper()
def _add_headers(self, env, headers):
"""Add http headers to environment."""
for (k, v) in headers.iteritems():
env_key = self._header_to_env_var(k)
env[env_key] = v
def _remove_headers(self, env, keys):
"""Remove http headers from environment."""
for k in keys:
env_key = self._header_to_env_var(k)
try:
del env[env_key]
except KeyError:
pass
def _get_header(self, env, key, default=None):
"""Get http header from environment."""
env_key = self._header_to_env_var(key)
return env.get(env_key, default)
def _cache_get(self, token):
"""Return token information from cache.
If token is invalid raise InvalidUserToken
return token only if fresh (not expired).
"""
if self._cache and token:
key = 'tokens/%s' % token
cached = self._cache.get(key)
if cached == 'invalid':
logger.debug('Cached Token %s is marked unauthorized', token)
raise InvalidUserToken('Token authorization failed')
if cached:
data, expires = cached
if time.time() < float(expires):
logger.debug('Returning cached token %s', token)
return data
else:
logger.debug('Cached Token %s seems expired', token)
def _cache_put(self, token, data):
"""Put token data into the cache.
Stores the parsed expire date in cache allowing
quick check of token freshness on retrieval.
"""
if self._cache and data:
key = 'tokens/%s' % token
if 'token' in data.get('access', {}):
timestamp = data['access']['token']['expires']
expires = self._iso8601.parse_date(timestamp).strftime('%s')
else:
logger.error('invalid token format')
return
logger.debug('Storing %s token in memcache', token)
self._cache.set(key,
(data, expires),
time=self.token_cache_time)
def _cache_store_invalid(self, token):
"""Store invalid token in cache."""
if self._cache:
key = 'tokens/%s' % token
logger.debug('Marking token %s as unauthorized in memcache', token)
self._cache.set(key,
'invalid',
time=self.token_cache_time)
def filter_factory(global_conf, **local_conf):
"""Returns a WSGI filter app for use with paste.deploy."""
conf = global_conf.copy()
conf.update(local_conf)
def auth_filter(app):
return AuthProtocol(app, conf)
return auth_filter
def app_factory(global_conf, **local_conf):
conf = global_conf.copy()
conf.update(local_conf)
return AuthProtocol(None, conf)