293 lines
9.4 KiB
Python
293 lines
9.4 KiB
Python
# Copyright 2017 Google Inc. All rights reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""A module that provides functions for handling rapt authentication."""
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import base64
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import getpass
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import json
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import logging
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import sys
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from oauth2client.contrib import reauth_errors
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from pyu2f import errors as u2ferrors
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from pyu2f import model
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from pyu2f.convenience import authenticator
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from six.moves import urllib
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REAUTH_API = 'https://reauth.googleapis.com/v2/sessions'
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REAUTH_SCOPE = 'https://www.googleapis.com/auth/accounts.reauth'
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REAUTH_ORIGIN = 'https://accounts.google.com'
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logger = logging.getLogger(__name__)
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def HandleErrors(msg):
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if 'error' in msg:
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raise reauth_errors.ReauthAPIError(msg['error']['message'])
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return msg
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def GetUserPassword(text):
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"""Get password from user.
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Override this function with a different logic if you are using this library
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outside a CLI. Returns the password."""
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return getpass.getpass(text)
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def InteractiveCheck():
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"""Check if we are in an interractive environment.
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If the rapt token needs refreshing, the user needs to answer the challenges.
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If the user is not in an interractive environment, the challenges can not be
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answered and we just wait for timeout for no reason."""
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return sys.stdin.isatty()
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def GetPrintCallback():
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"""Get preferred output function."""
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return sys.stderr.write
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class ReauthChallenge(object):
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"""Base class for reauth challenges."""
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def __init__(self, http_request, access_token):
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self.http_request = http_request
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self.access_token = access_token
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def GetName(self):
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"""Returns the name of the challenge."""
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raise NotImplementedError()
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def IsLocallyEligible(self):
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"""Returns true if a challenge is supported locally on this machine."""
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raise NotImplementedError()
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def Execute(self, metadata, session_id):
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"""Execute challenge logic and pass credentials to reauth API."""
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client_input = self.InternalObtainCredentials(metadata)
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if not client_input:
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return None
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body = {
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'sessionId': session_id,
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'challengeId': metadata['challengeId'],
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'action': 'RESPOND',
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'proposalResponse': client_input,
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}
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_, content = self.http_request(
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'{0}/{1}:continue'.format(REAUTH_API, session_id),
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method='POST',
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body=json.dumps(body),
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headers={'Authorization': 'Bearer ' + self.access_token}
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)
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response = json.loads(content)
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HandleErrors(response)
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return response
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def InternalObtainCredentials(self, metadata):
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"""Performs logic required to obtain credentials and returns it."""
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raise NotImplementedError()
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class PasswordChallenge(ReauthChallenge):
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"""Challenge that asks for user's password."""
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def GetName(self):
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return 'PASSWORD'
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def IsLocallyEligible(self):
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return True
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def InternalObtainCredentials(self, unused_metadata):
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passwd = GetUserPassword('Please enter your password:')
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if not passwd:
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passwd = ' ' # avoid the server crashing in case of no password :D
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return {'credential': passwd}
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class SecurityKeyChallenge(ReauthChallenge):
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"""Challenge that asks for user's security key touch."""
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def GetName(self):
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return 'SECURITY_KEY'
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def IsLocallyEligible(self):
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return True
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def InternalObtainCredentials(self, metadata):
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sk = metadata['securityKey']
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challenges = sk['challenges']
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app_id = sk['applicationId']
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challenge_data = []
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for c in challenges:
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kh = c['keyHandle'].encode('ascii')
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key = model.RegisteredKey(bytearray(base64.urlsafe_b64decode(kh)))
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challenge = c['challenge'].encode('ascii')
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challenge = base64.urlsafe_b64decode(challenge)
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challenge_data.append({'key': key, 'challenge': challenge})
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try:
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api = authenticator.CreateCompositeAuthenticator(REAUTH_ORIGIN)
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response = api.Authenticate(app_id, challenge_data,
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print_callback=GetPrintCallback())
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return {'securityKey': response}
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except u2ferrors.U2FError as e:
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if e.code == u2ferrors.U2FError.DEVICE_INELIGIBLE:
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GetPrintCallback()('Ineligible security key.\n')
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elif e.code == u2ferrors.U2FError.TIMEOUT:
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GetPrintCallback()(
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'Timed out while waiting for security key touch.\n')
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else:
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raise e
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except u2ferrors.NoDeviceFoundError:
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GetPrintCallback()('No security key found.\n')
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return None
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class SamlChallenge(ReauthChallenge):
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"""Challenge that asks SAML users to complete SAML login."""
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def GetName(self):
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return 'SAML'
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def IsLocallyEligible(self):
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return True
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def InternalObtainCredentials(self, unused_metadata):
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# Margic Arch has not fully supported returning a proper redirect URL
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# for programmatic SAML users today. So we error out here and request
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# users to complete a web login.
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raise reauth_errors.ReauthSamlLoginRequiredError()
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class ReauthManager(object):
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"""Reauth manager class that handles reauth challenges."""
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def __init__(self, http_request, access_token):
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self.http_request = http_request
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self.access_token = access_token
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self.challenges = self.InternalBuildChallenges()
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def InternalBuildChallenges(self):
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out = {}
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for c in [SecurityKeyChallenge(self.http_request, self.access_token),
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PasswordChallenge(self.http_request, self.access_token),
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SamlChallenge(self.http_request, self.access_token)]:
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if c.IsLocallyEligible():
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out[c.GetName()] = c
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return out
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def InternalStart(self, requested_scopes):
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"""Does initial request to reauth API and initialize the challenges."""
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body = {'supportedChallengeTypes': list(self.challenges.keys())}
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if requested_scopes:
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body['oauthScopesForDomainPolicyLookup'] = requested_scopes
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_, content = self.http_request(
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'{0}:start'.format(REAUTH_API),
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method='POST',
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body=json.dumps(body),
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headers={'Authorization': 'Bearer ' + self.access_token}
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)
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response = json.loads(content)
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HandleErrors(response)
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return response
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def DoOneRoundOfChallenges(self, msg):
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next_msg = None
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for challenge in msg['challenges']:
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if challenge['status'] != 'READY':
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# Skip non-activated challneges.
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continue
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c = self.challenges[challenge['challengeType']]
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next_msg = c.Execute(challenge, msg['sessionId'])
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return next_msg
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def ObtainProofOfReauth(self, requested_scopes=None):
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"""Obtain proof of reauth (rapt token)."""
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msg = None
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max_challenge_count = 5
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while max_challenge_count:
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max_challenge_count -= 1
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if not msg:
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msg = self.InternalStart(requested_scopes)
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if msg['status'] == 'AUTHENTICATED':
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return msg['encodedProofOfReauthToken']
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if not (msg['status'] == 'CHALLENGE_REQUIRED' or
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msg['status'] == 'CHALLENGE_PENDING'):
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raise reauth_errors.ReauthAPIError(
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'Challenge status {0}'.format(msg['status']))
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if not InteractiveCheck():
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raise reauth_errors.ReauthUnattendedError()
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msg = self.DoOneRoundOfChallenges(msg)
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# If we got here it means we didn't get authenticated.
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raise reauth_errors.ReauthFailError()
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def ObtainRapt(http_request, access_token, requested_scopes):
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rm = ReauthManager(http_request, access_token)
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rapt = rm.ObtainProofOfReauth(requested_scopes=requested_scopes)
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return rapt
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def GetRaptToken(http_request, client_id, client_secret, refresh_token,
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token_uri, scopes=None):
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"""Given an http request method and refresh_token, get rapt token."""
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GetPrintCallback()('Reauthentication required.\n')
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# Get access token for reauth.
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query_params = {
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'client_id': client_id,
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'client_secret': client_secret,
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'refresh_token': refresh_token,
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'scope': REAUTH_SCOPE,
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'grant_type': 'refresh_token',
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}
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_, content = http_request(
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token_uri,
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method='POST',
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body=urllib.parse.urlencode(query_params),
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headers={'Content-Type': 'application/x-www-form-urlencoded'},
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)
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try:
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reauth_access_token = json.loads(content)['access_token']
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except (ValueError, KeyError):
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raise reauth_errors.ReauthAccessTokenRefreshError
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# Get rapt token from reauth API.
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rapt_token = ObtainRapt(
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http_request,
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reauth_access_token,
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requested_scopes=scopes)
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return rapt_token
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