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Diffstat (limited to 'google/oauth2/service_account.py')
| -rw-r--r-- | google/oauth2/service_account.py | 687 |
1 files changed, 687 insertions, 0 deletions
diff --git a/google/oauth2/service_account.py b/google/oauth2/service_account.py new file mode 100644 index 0000000..ecaac03 --- /dev/null +++ b/google/oauth2/service_account.py @@ -0,0 +1,687 @@ +# Copyright 2016 Google 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. + +"""Service Accounts: JSON Web Token (JWT) Profile for OAuth 2.0 + +This module implements the JWT Profile for OAuth 2.0 Authorization Grants +as defined by `RFC 7523`_ with particular support for how this RFC is +implemented in Google's infrastructure. Google refers to these credentials +as *Service Accounts*. + +Service accounts are used for server-to-server communication, such as +interactions between a web application server and a Google service. The +service account belongs to your application instead of to an individual end +user. In contrast to other OAuth 2.0 profiles, no users are involved and your +application "acts" as the service account. + +Typically an application uses a service account when the application uses +Google APIs to work with its own data rather than a user's data. For example, +an application that uses Google Cloud Datastore for data persistence would use +a service account to authenticate its calls to the Google Cloud Datastore API. +However, an application that needs to access a user's Drive documents would +use the normal OAuth 2.0 profile. + +Additionally, Google Apps domain administrators can grant service accounts +`domain-wide delegation`_ authority to access user data on behalf of users in +the domain. + +This profile uses a JWT to acquire an OAuth 2.0 access token. The JWT is used +in place of the usual authorization token returned during the standard +OAuth 2.0 Authorization Code grant. The JWT is only used for this purpose, as +the acquired access token is used as the bearer token when making requests +using these credentials. + +This profile differs from normal OAuth 2.0 profile because no user consent +step is required. The use of the private key allows this profile to assert +identity directly. + +This profile also differs from the :mod:`google.auth.jwt` authentication +because the JWT credentials use the JWT directly as the bearer token. This +profile instead only uses the JWT to obtain an OAuth 2.0 access token. The +obtained OAuth 2.0 access token is used as the bearer token. + +Domain-wide delegation +---------------------- + +Domain-wide delegation allows a service account to access user data on +behalf of any user in a Google Apps domain without consent from the user. +For example, an application that uses the Google Calendar API to add events to +the calendars of all users in a Google Apps domain would use a service account +to access the Google Calendar API on behalf of users. + +The Google Apps administrator must explicitly authorize the service account to +do this. This authorization step is referred to as "delegating domain-wide +authority" to a service account. + +You can use domain-wise delegation by creating a set of credentials with a +specific subject using :meth:`~Credentials.with_subject`. + +.. _RFC 7523: https://tools.ietf.org/html/rfc7523 +""" + +import copy +import datetime + +from google.auth import _helpers +from google.auth import _service_account_info +from google.auth import credentials +from google.auth import jwt +from google.oauth2 import _client + +_DEFAULT_TOKEN_LIFETIME_SECS = 3600 # 1 hour in seconds +_GOOGLE_OAUTH2_TOKEN_ENDPOINT = "https://oauth2.googleapis.com/token" + + +class Credentials( + credentials.Signing, credentials.Scoped, credentials.CredentialsWithQuotaProject +): + """Service account credentials + + Usually, you'll create these credentials with one of the helper + constructors. To create credentials using a Google service account + private key JSON file:: + + credentials = service_account.Credentials.from_service_account_file( + 'service-account.json') + + Or if you already have the service account file loaded:: + + service_account_info = json.load(open('service_account.json')) + credentials = service_account.Credentials.from_service_account_info( + service_account_info) + + Both helper methods pass on arguments to the constructor, so you can + specify additional scopes and a subject if necessary:: + + credentials = service_account.Credentials.from_service_account_file( + 'service-account.json', + scopes=['email'], + subject='user@example.com') + + The credentials are considered immutable. If you want to modify the scopes + or the subject used for delegation, use :meth:`with_scopes` or + :meth:`with_subject`:: + + scoped_credentials = credentials.with_scopes(['email']) + delegated_credentials = credentials.with_subject(subject) + + To add a quota project, use :meth:`with_quota_project`:: + + credentials = credentials.with_quota_project('myproject-123') + """ + + def __init__( + self, + signer, + service_account_email, + token_uri, + scopes=None, + default_scopes=None, + subject=None, + project_id=None, + quota_project_id=None, + additional_claims=None, + always_use_jwt_access=False, + ): + """ + Args: + signer (google.auth.crypt.Signer): The signer used to sign JWTs. + service_account_email (str): The service account's email. + scopes (Sequence[str]): User-defined scopes to request during the + authorization grant. + default_scopes (Sequence[str]): Default scopes passed by a + Google client library. Use 'scopes' for user-defined scopes. + token_uri (str): The OAuth 2.0 Token URI. + subject (str): For domain-wide delegation, the email address of the + user to for which to request delegated access. + project_id (str): Project ID associated with the service account + credential. + quota_project_id (Optional[str]): The project ID used for quota and + billing. + additional_claims (Mapping[str, str]): Any additional claims for + the JWT assertion used in the authorization grant. + always_use_jwt_access (Optional[bool]): Whether self signed JWT should + be always used. + + .. note:: Typically one of the helper constructors + :meth:`from_service_account_file` or + :meth:`from_service_account_info` are used instead of calling the + constructor directly. + """ + super(Credentials, self).__init__() + + self._scopes = scopes + self._default_scopes = default_scopes + self._signer = signer + self._service_account_email = service_account_email + self._subject = subject + self._project_id = project_id + self._quota_project_id = quota_project_id + self._token_uri = token_uri + self._always_use_jwt_access = always_use_jwt_access + + self._jwt_credentials = None + + if additional_claims is not None: + self._additional_claims = additional_claims + else: + self._additional_claims = {} + + @classmethod + def _from_signer_and_info(cls, signer, info, **kwargs): + """Creates a Credentials instance from a signer and service account + info. + + Args: + signer (google.auth.crypt.Signer): The signer used to sign JWTs. + info (Mapping[str, str]): The service account info. + kwargs: Additional arguments to pass to the constructor. + + Returns: + google.auth.jwt.Credentials: The constructed credentials. + + Raises: + ValueError: If the info is not in the expected format. + """ + return cls( + signer, + service_account_email=info["client_email"], + token_uri=info["token_uri"], + project_id=info.get("project_id"), + **kwargs + ) + + @classmethod + def from_service_account_info(cls, info, **kwargs): + """Creates a Credentials instance from parsed service account info. + + Args: + info (Mapping[str, str]): The service account info in Google + format. + kwargs: Additional arguments to pass to the constructor. + + Returns: + google.auth.service_account.Credentials: The constructed + credentials. + + Raises: + ValueError: If the info is not in the expected format. + """ + signer = _service_account_info.from_dict( + info, require=["client_email", "token_uri"] + ) + return cls._from_signer_and_info(signer, info, **kwargs) + + @classmethod + def from_service_account_file(cls, filename, **kwargs): + """Creates a Credentials instance from a service account json file. + + Args: + filename (str): The path to the service account json file. + kwargs: Additional arguments to pass to the constructor. + + Returns: + google.auth.service_account.Credentials: The constructed + credentials. + """ + info, signer = _service_account_info.from_filename( + filename, require=["client_email", "token_uri"] + ) + return cls._from_signer_and_info(signer, info, **kwargs) + + @property + def service_account_email(self): + """The service account email.""" + return self._service_account_email + + @property + def project_id(self): + """Project ID associated with this credential.""" + return self._project_id + + @property + def requires_scopes(self): + """Checks if the credentials requires scopes. + + Returns: + bool: True if there are no scopes set otherwise False. + """ + return True if not self._scopes else False + + @_helpers.copy_docstring(credentials.Scoped) + def with_scopes(self, scopes, default_scopes=None): + return self.__class__( + self._signer, + service_account_email=self._service_account_email, + scopes=scopes, + default_scopes=default_scopes, + token_uri=self._token_uri, + subject=self._subject, + project_id=self._project_id, + quota_project_id=self._quota_project_id, + additional_claims=self._additional_claims.copy(), + always_use_jwt_access=self._always_use_jwt_access, + ) + + def with_always_use_jwt_access(self, always_use_jwt_access): + """Create a copy of these credentials with the specified always_use_jwt_access value. + + Args: + always_use_jwt_access (bool): Whether always use self signed JWT or not. + + Returns: + google.auth.service_account.Credentials: A new credentials + instance. + """ + return self.__class__( + self._signer, + service_account_email=self._service_account_email, + scopes=self._scopes, + default_scopes=self._default_scopes, + token_uri=self._token_uri, + subject=self._subject, + project_id=self._project_id, + quota_project_id=self._quota_project_id, + additional_claims=self._additional_claims.copy(), + always_use_jwt_access=always_use_jwt_access, + ) + + def with_subject(self, subject): + """Create a copy of these credentials with the specified subject. + + Args: + subject (str): The subject claim. + + Returns: + google.auth.service_account.Credentials: A new credentials + instance. + """ + return self.__class__( + self._signer, + service_account_email=self._service_account_email, + scopes=self._scopes, + default_scopes=self._default_scopes, + token_uri=self._token_uri, + subject=subject, + project_id=self._project_id, + quota_project_id=self._quota_project_id, + additional_claims=self._additional_claims.copy(), + always_use_jwt_access=self._always_use_jwt_access, + ) + + def with_claims(self, additional_claims): + """Returns a copy of these credentials with modified claims. + + Args: + additional_claims (Mapping[str, str]): Any additional claims for + the JWT payload. This will be merged with the current + additional claims. + + Returns: + google.auth.service_account.Credentials: A new credentials + instance. + """ + new_additional_claims = copy.deepcopy(self._additional_claims) + new_additional_claims.update(additional_claims or {}) + + return self.__class__( + self._signer, + service_account_email=self._service_account_email, + scopes=self._scopes, + default_scopes=self._default_scopes, + token_uri=self._token_uri, + subject=self._subject, + project_id=self._project_id, + quota_project_id=self._quota_project_id, + additional_claims=new_additional_claims, + always_use_jwt_access=self._always_use_jwt_access, + ) + + @_helpers.copy_docstring(credentials.CredentialsWithQuotaProject) + def with_quota_project(self, quota_project_id): + + return self.__class__( + self._signer, + service_account_email=self._service_account_email, + default_scopes=self._default_scopes, + scopes=self._scopes, + token_uri=self._token_uri, + subject=self._subject, + project_id=self._project_id, + quota_project_id=quota_project_id, + additional_claims=self._additional_claims.copy(), + always_use_jwt_access=self._always_use_jwt_access, + ) + + def _make_authorization_grant_assertion(self): + """Create the OAuth 2.0 assertion. + + This assertion is used during the OAuth 2.0 grant to acquire an + access token. + + Returns: + bytes: The authorization grant assertion. + """ + now = _helpers.utcnow() + lifetime = datetime.timedelta(seconds=_DEFAULT_TOKEN_LIFETIME_SECS) + expiry = now + lifetime + + payload = { + "iat": _helpers.datetime_to_secs(now), + "exp": _helpers.datetime_to_secs(expiry), + # The issuer must be the service account email. + "iss": self._service_account_email, + # The audience must be the auth token endpoint's URI + "aud": _GOOGLE_OAUTH2_TOKEN_ENDPOINT, + "scope": _helpers.scopes_to_string(self._scopes or ()), + } + + payload.update(self._additional_claims) + + # The subject can be a user email for domain-wide delegation. + if self._subject: + payload.setdefault("sub", self._subject) + + token = jwt.encode(self._signer, payload) + + return token + + @_helpers.copy_docstring(credentials.Credentials) + def refresh(self, request): + # Since domain wide delegation doesn't work with self signed JWT. If + # subject exists, then we should not use self signed JWT. + if self._subject is None and self._jwt_credentials is not None: + self._jwt_credentials.refresh(request) + self.token = self._jwt_credentials.token + self.expiry = self._jwt_credentials.expiry + else: + assertion = self._make_authorization_grant_assertion() + access_token, expiry, _ = _client.jwt_grant( + request, self._token_uri, assertion + ) + self.token = access_token + self.expiry = expiry + + def _create_self_signed_jwt(self, audience): + """Create a self-signed JWT from the credentials if requirements are met. + + Args: + audience (str): The service URL. ``https://[API_ENDPOINT]/`` + """ + # https://google.aip.dev/auth/4111 + if self._always_use_jwt_access: + if self._scopes: + self._jwt_credentials = jwt.Credentials.from_signing_credentials( + self, None, additional_claims={"scope": " ".join(self._scopes)} + ) + elif audience: + self._jwt_credentials = jwt.Credentials.from_signing_credentials( + self, audience + ) + elif self._default_scopes: + self._jwt_credentials = jwt.Credentials.from_signing_credentials( + self, + None, + additional_claims={"scope": " ".join(self._default_scopes)}, + ) + elif not self._scopes and audience: + self._jwt_credentials = jwt.Credentials.from_signing_credentials( + self, audience + ) + + @_helpers.copy_docstring(credentials.Signing) + def sign_bytes(self, message): + return self._signer.sign(message) + + @property + @_helpers.copy_docstring(credentials.Signing) + def signer(self): + return self._signer + + @property + @_helpers.copy_docstring(credentials.Signing) + def signer_email(self): + return self._service_account_email + + +class IDTokenCredentials(credentials.Signing, credentials.CredentialsWithQuotaProject): + """Open ID Connect ID Token-based service account credentials. + + These credentials are largely similar to :class:`.Credentials`, but instead + of using an OAuth 2.0 Access Token as the bearer token, they use an Open + ID Connect ID Token as the bearer token. These credentials are useful when + communicating to services that require ID Tokens and can not accept access + tokens. + + Usually, you'll create these credentials with one of the helper + constructors. To create credentials using a Google service account + private key JSON file:: + + credentials = ( + service_account.IDTokenCredentials.from_service_account_file( + 'service-account.json')) + + + Or if you already have the service account file loaded:: + + service_account_info = json.load(open('service_account.json')) + credentials = ( + service_account.IDTokenCredentials.from_service_account_info( + service_account_info)) + + + Both helper methods pass on arguments to the constructor, so you can + specify additional scopes and a subject if necessary:: + + credentials = ( + service_account.IDTokenCredentials.from_service_account_file( + 'service-account.json', + scopes=['email'], + subject='user@example.com')) + + + The credentials are considered immutable. If you want to modify the scopes + or the subject used for delegation, use :meth:`with_scopes` or + :meth:`with_subject`:: + + scoped_credentials = credentials.with_scopes(['email']) + delegated_credentials = credentials.with_subject(subject) + + """ + + def __init__( + self, + signer, + service_account_email, + token_uri, + target_audience, + additional_claims=None, + quota_project_id=None, + ): + """ + Args: + signer (google.auth.crypt.Signer): The signer used to sign JWTs. + service_account_email (str): The service account's email. + token_uri (str): The OAuth 2.0 Token URI. + target_audience (str): The intended audience for these credentials, + used when requesting the ID Token. The ID Token's ``aud`` claim + will be set to this string. + additional_claims (Mapping[str, str]): Any additional claims for + the JWT assertion used in the authorization grant. + quota_project_id (Optional[str]): The project ID used for quota and billing. + .. note:: Typically one of the helper constructors + :meth:`from_service_account_file` or + :meth:`from_service_account_info` are used instead of calling the + constructor directly. + """ + super(IDTokenCredentials, self).__init__() + self._signer = signer + self._service_account_email = service_account_email + self._token_uri = token_uri + self._target_audience = target_audience + self._quota_project_id = quota_project_id + + if additional_claims is not None: + self._additional_claims = additional_claims + else: + self._additional_claims = {} + + @classmethod + def _from_signer_and_info(cls, signer, info, **kwargs): + """Creates a credentials instance from a signer and service account + info. + + Args: + signer (google.auth.crypt.Signer): The signer used to sign JWTs. + info (Mapping[str, str]): The service account info. + kwargs: Additional arguments to pass to the constructor. + + Returns: + google.auth.jwt.IDTokenCredentials: The constructed credentials. + + Raises: + ValueError: If the info is not in the expected format. + """ + kwargs.setdefault("service_account_email", info["client_email"]) + kwargs.setdefault("token_uri", info["token_uri"]) + return cls(signer, **kwargs) + + @classmethod + def from_service_account_info(cls, info, **kwargs): + """Creates a credentials instance from parsed service account info. + + Args: + info (Mapping[str, str]): The service account info in Google + format. + kwargs: Additional arguments to pass to the constructor. + + Returns: + google.auth.service_account.IDTokenCredentials: The constructed + credentials. + + Raises: + ValueError: If the info is not in the expected format. + """ + signer = _service_account_info.from_dict( + info, require=["client_email", "token_uri"] + ) + return cls._from_signer_and_info(signer, info, **kwargs) + + @classmethod + def from_service_account_file(cls, filename, **kwargs): + """Creates a credentials instance from a service account json file. + + Args: + filename (str): The path to the service account json file. + kwargs: Additional arguments to pass to the constructor. + + Returns: + google.auth.service_account.IDTokenCredentials: The constructed + credentials. + """ + info, signer = _service_account_info.from_filename( + filename, require=["client_email", "token_uri"] + ) + return cls._from_signer_and_info(signer, info, **kwargs) + + def with_target_audience(self, target_audience): + """Create a copy of these credentials with the specified target + audience. + + Args: + target_audience (str): The intended audience for these credentials, + used when requesting the ID Token. + + Returns: + google.auth.service_account.IDTokenCredentials: A new credentials + instance. + """ + return self.__class__( + self._signer, + service_account_email=self._service_account_email, + token_uri=self._token_uri, + target_audience=target_audience, + additional_claims=self._additional_claims.copy(), + quota_project_id=self.quota_project_id, + ) + + @_helpers.copy_docstring(credentials.CredentialsWithQuotaProject) + def with_quota_project(self, quota_project_id): + return self.__class__( + self._signer, + service_account_email=self._service_account_email, + token_uri=self._token_uri, + target_audience=self._target_audience, + additional_claims=self._additional_claims.copy(), + quota_project_id=quota_project_id, + ) + + def _make_authorization_grant_assertion(self): + """Create the OAuth 2.0 assertion. + + This assertion is used during the OAuth 2.0 grant to acquire an + ID token. + + Returns: + bytes: The authorization grant assertion. + """ + now = _helpers.utcnow() + lifetime = datetime.timedelta(seconds=_DEFAULT_TOKEN_LIFETIME_SECS) + expiry = now + lifetime + + payload = { + "iat": _helpers.datetime_to_secs(now), + "exp": _helpers.datetime_to_secs(expiry), + # The issuer must be the service account email. + "iss": self.service_account_email, + # The audience must be the auth token endpoint's URI + "aud": _GOOGLE_OAUTH2_TOKEN_ENDPOINT, + # The target audience specifies which service the ID token is + # intended for. + "target_audience": self._target_audience, + } + + payload.update(self._additional_claims) + + token = jwt.encode(self._signer, payload) + + return token + + @_helpers.copy_docstring(credentials.Credentials) + def refresh(self, request): + assertion = self._make_authorization_grant_assertion() + access_token, expiry, _ = _client.id_token_jwt_grant( + request, self._token_uri, assertion + ) + self.token = access_token + self.expiry = expiry + + @property + def service_account_email(self): + """The service account email.""" + return self._service_account_email + + @_helpers.copy_docstring(credentials.Signing) + def sign_bytes(self, message): + return self._signer.sign(message) + + @property + @_helpers.copy_docstring(credentials.Signing) + def signer(self): + return self._signer + + @property + @_helpers.copy_docstring(credentials.Signing) + def signer_email(self): + return self._service_account_email |