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1# Copyright 2016 Google LLC
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7# http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
15"""Authorization support for gRPC."""
17from __future__ import absolute_import
19import logging
20import warnings
22from google.auth import exceptions
23from google.auth.transport import _mtls_helper
24from google.auth.transport import mtls
25from google.oauth2 import service_account
27try:
28 import grpc # type: ignore
29except ImportError as caught_exc: # pragma: NO COVER
30 raise ImportError(
31 "gRPC is not installed from please install the grpcio package to use the gRPC transport."
32 ) from caught_exc
35_grpc_ver_str = getattr(grpc, "__version__", None)
36if isinstance(_grpc_ver_str, str):
37 _parts = []
38 for _part in _grpc_ver_str.split("."):
39 try:
40 _parts.append(int(_part))
41 except ValueError:
42 break
43 if _parts and tuple(_parts) < (1, 83, 0):
44 warnings.warn(
45 "grpcio < 1.83.0 does not support Post-Quantum Cryptography (PQC). "
46 "Support for non-PQC environments is deprecated. In October 2026, "
47 "google-auth will raise its minimum requirements "
48 "to enforce grpcio >= 1.83.0. "
49 "For more details on Google Cloud's post-quantum security migration, visit: "
50 "https://cloud.google.com/security/resources/post-quantum-cryptography",
51 FutureWarning,
52 )
54_LOGGER = logging.getLogger(__name__)
57class AuthMetadataPlugin(grpc.AuthMetadataPlugin):
58 """A `gRPC AuthMetadataPlugin`_ that inserts the credentials into each
59 request.
61 .. _gRPC AuthMetadataPlugin:
62 http://www.grpc.io/grpc/python/grpc.html#grpc.AuthMetadataPlugin
64 Args:
65 credentials (google.auth.credentials.Credentials): The credentials to
66 add to requests.
67 request (google.auth.transport.Request): A HTTP transport request
68 object used to refresh credentials as needed.
69 default_host (Optional[str]): A host like "pubsub.googleapis.com".
70 This is used when a self-signed JWT is created from service
71 account credentials.
72 suppress_metrics_header (bool): When enabled, ``x-goog-api-client``
73 will be stripped from authorization headers.
74 """
76 def __init__(
77 self, credentials, request, default_host=None, *, suppress_metrics_header=False
78 ):
79 # pylint: disable=no-value-for-parameter
80 # pylint doesn't realize that the super method takes no arguments
81 # because this class is the same name as the superclass.
82 super(AuthMetadataPlugin, self).__init__()
83 self._credentials = credentials
84 self._request = request
85 self._default_host = default_host
86 self._suppress_metrics_header = suppress_metrics_header
88 def _get_authorization_headers(self, context):
89 """Gets the authorization headers for a request.
91 Returns:
92 Sequence[Tuple[str, str]]: A list of request headers (key, value)
93 to add to the request.
94 """
95 headers = {}
97 # https://google.aip.dev/auth/4111
98 # Attempt to use self-signed JWTs when a service account is used.
99 # A default host must be explicitly provided since it cannot always
100 # be determined from the context.service_url.
101 if isinstance(self._credentials, service_account.Credentials):
102 self._credentials._create_self_signed_jwt(
103 "https://{}/".format(self._default_host) if self._default_host else None
104 )
106 self._credentials.before_request(
107 self._request, context.method_name, context.service_url, headers
108 )
110 if self._suppress_metrics_header and "x-goog-api-client" in headers:
111 del headers["x-goog-api-client"]
113 return list(headers.items())
115 def __call__(self, context, callback):
116 """Passes authorization metadata into the given callback.
118 Args:
119 context (grpc.AuthMetadataContext): The RPC context.
120 callback (grpc.AuthMetadataPluginCallback): The callback that will
121 be invoked to pass in the authorization metadata.
122 """
123 callback(self._get_authorization_headers(context), None)
126def secure_authorized_channel(
127 credentials,
128 request,
129 target,
130 ssl_credentials=None,
131 client_cert_callback=None,
132 **kwargs
133):
134 """Creates a secure authorized gRPC channel.
136 This creates a channel with SSL and :class:`AuthMetadataPlugin`. This
137 channel can be used to create a stub that can make authorized requests.
138 Users can configure client certificate or rely on device certificates to
139 establish a mutual TLS channel, if the `GOOGLE_API_USE_CLIENT_CERTIFICATE`
140 variable is explicitly set to `true`.
142 Example::
144 import google.auth
145 import google.auth.transport.grpc
146 import google.auth.transport.requests
147 from google.cloud.speech.v1 import cloud_speech_pb2
149 # Get credentials.
150 credentials, _ = google.auth.default()
152 # Get an HTTP request function to refresh credentials.
153 request = google.auth.transport.requests.Request()
155 # Create a channel.
156 channel = google.auth.transport.grpc.secure_authorized_channel(
157 credentials, regular_endpoint, request,
158 ssl_credentials=grpc.ssl_channel_credentials())
160 # Use the channel to create a stub.
161 cloud_speech.create_Speech_stub(channel)
163 Usage:
165 There are actually a couple of options to create a channel, depending on if
166 you want to create a regular or mutual TLS channel.
168 First let's list the endpoints (regular vs mutual TLS) to choose from::
170 regular_endpoint = 'speech.googleapis.com:443'
171 mtls_endpoint = 'speech.mtls.googleapis.com:443'
173 Option 1: create a regular (non-mutual) TLS channel by explicitly setting
174 the ssl_credentials::
176 regular_ssl_credentials = grpc.ssl_channel_credentials()
178 channel = google.auth.transport.grpc.secure_authorized_channel(
179 credentials, request, regular_endpoint,
180 ssl_credentials=regular_ssl_credentials)
182 Option 2: create a mutual TLS channel by calling a callback which returns
183 the client side certificate and the key (Note that
184 `GOOGLE_API_USE_CLIENT_CERTIFICATE` environment variable must be explicitly
185 set to `true`)::
187 def my_client_cert_callback():
188 code_to_load_client_cert_and_key()
189 if loaded:
190 return (pem_cert_bytes, pem_key_bytes)
191 raise MyClientCertFailureException()
193 try:
194 channel = google.auth.transport.grpc.secure_authorized_channel(
195 credentials, request, mtls_endpoint,
196 client_cert_callback=my_client_cert_callback)
197 except MyClientCertFailureException:
198 # handle the exception
200 Option 3: use application default SSL credentials. It searches and uses
201 the command in a context aware metadata file, which is available on devices
202 with endpoint verification support (Note that
203 `GOOGLE_API_USE_CLIENT_CERTIFICATE` environment variable must be explicitly
204 set to `true`).
205 See https://cloud.google.com/endpoint-verification/docs/overview::
207 try:
208 default_ssl_credentials = SslCredentials()
209 except:
210 # Exception can be raised if the context aware metadata is malformed.
211 # See :class:`SslCredentials` for the possible exceptions.
213 # Choose the endpoint based on the SSL credentials type.
214 if default_ssl_credentials.is_mtls:
215 endpoint_to_use = mtls_endpoint
216 else:
217 endpoint_to_use = regular_endpoint
218 channel = google.auth.transport.grpc.secure_authorized_channel(
219 credentials, request, endpoint_to_use,
220 ssl_credentials=default_ssl_credentials)
222 Option 4: not setting ssl_credentials and client_cert_callback. For devices
223 without endpoint verification support or `GOOGLE_API_USE_CLIENT_CERTIFICATE`
224 environment variable is not `true`, a regular TLS channel is created;
225 otherwise, a mutual TLS channel is created, however, the call should be
226 wrapped in a try/except block in case of malformed context aware metadata.
228 The following code uses regular_endpoint, it works the same no matter the
229 created channle is regular or mutual TLS. Regular endpoint ignores client
230 certificate and key::
232 channel = google.auth.transport.grpc.secure_authorized_channel(
233 credentials, request, regular_endpoint)
235 The following code uses mtls_endpoint, if the created channle is regular,
236 and API mtls_endpoint is confgured to require client SSL credentials, API
237 calls using this channel will be rejected::
239 channel = google.auth.transport.grpc.secure_authorized_channel(
240 credentials, request, mtls_endpoint)
242 Args:
243 credentials (google.auth.credentials.Credentials): The credentials to
244 add to requests.
245 request (google.auth.transport.Request): A HTTP transport request
246 object used to refresh credentials as needed. Even though gRPC
247 is a separate transport, there's no way to refresh the credentials
248 without using a standard http transport.
249 target (str): The host and port of the service.
250 ssl_credentials (grpc.ChannelCredentials): Optional SSL channel
251 credentials. This can be used to specify different certificates.
252 This argument is mutually exclusive with client_cert_callback;
253 providing both will raise an exception.
254 If ssl_credentials and client_cert_callback are None, application
255 default SSL credentials are used if `GOOGLE_API_USE_CLIENT_CERTIFICATE`
256 environment variable is explicitly set to `true`, otherwise one way TLS
257 SSL credentials are used.
258 client_cert_callback (Callable[[], (bytes, bytes)]): Optional
259 callback function to obtain client certicate and key for mutual TLS
260 connection. This argument is mutually exclusive with
261 ssl_credentials; providing both will raise an exception.
262 This argument does nothing unless `GOOGLE_API_USE_CLIENT_CERTIFICATE`
263 environment variable is explicitly set to `true`.
264 kwargs: Additional arguments to pass to :func:`grpc.secure_channel`.
266 Returns:
267 grpc.Channel: The created gRPC channel.
269 Raises:
270 google.auth.exceptions.MutualTLSChannelError: If mutual TLS channel
271 creation failed for any reason.
272 """
273 # Create the metadata plugin for inserting the authorization header.
274 metadata_plugin = AuthMetadataPlugin(credentials, request)
276 # Create a set of grpc.CallCredentials using the metadata plugin.
277 google_auth_credentials = grpc.metadata_call_credentials(metadata_plugin)
279 if ssl_credentials and client_cert_callback:
280 raise exceptions.MalformedError(
281 "Received both ssl_credentials and client_cert_callback; "
282 "these are mutually exclusive."
283 )
285 # If SSL credentials are not explicitly set, try client_cert_callback and ADC.
286 if not ssl_credentials:
287 use_client_cert = _mtls_helper.check_use_client_cert()
288 if use_client_cert and client_cert_callback:
289 # Use the callback if provided.
290 cert, key = client_cert_callback()
291 ssl_credentials = grpc.ssl_channel_credentials(
292 certificate_chain=cert, private_key=key
293 )
294 elif use_client_cert:
295 # Use application default SSL credentials.
296 adc_ssl_credentils = SslCredentials()
297 ssl_credentials = adc_ssl_credentils.ssl_credentials
298 else:
299 ssl_credentials = grpc.ssl_channel_credentials()
301 # Combine the ssl credentials and the authorization credentials.
302 composite_credentials = grpc.composite_channel_credentials(
303 ssl_credentials, google_auth_credentials
304 )
306 return grpc.secure_channel(target, composite_credentials, **kwargs)
309class SslCredentials:
310 """Class for application default SSL credentials.
312 Mutual TLS (mTLS) is enabled if either:
314 1. The `GOOGLE_API_USE_CLIENT_CERTIFICATE` environment variable is explicitly
315 set to `"true"`.
316 2. The `GOOGLE_API_USE_CLIENT_CERTIFICATE` environment variable is unset or empty,
317 but a valid workload certificate configuration is found (e.g., via the
318 `GOOGLE_API_CERTIFICATE_CONFIG` environment variable or the default gcloud config path).
320 See https://google.aip.dev/auth/4114 for client certificate discovery details.
322 If client certificate usage is enabled, then for devices with endpoint
323 verification support, a device certificate will be automatically loaded and
324 mutual TLS will be established.
325 See https://cloud.google.com/endpoint-verification/docs/overview.
326 """
328 def __init__(self):
329 use_client_cert = _mtls_helper.check_use_client_cert()
330 if not use_client_cert:
331 self._is_mtls = False
332 else:
333 self._is_mtls = mtls.has_default_client_cert_source()
335 @property
336 def ssl_credentials(self):
337 """Get the created SSL channel credentials.
339 For devices with endpoint verification support, if the device certificate
340 loading has any problems, corresponding exceptions will be raised. For
341 a device without endpoint verification support, no exceptions will be
342 raised.
344 Returns:
345 grpc.ChannelCredentials: The created grpc channel credentials.
347 Raises:
348 google.auth.exceptions.MutualTLSChannelError: If mutual TLS channel
349 creation failed for any reason.
350 """
351 if self._is_mtls:
352 try:
353 has_cert, cert, key, _ = _mtls_helper.get_client_ssl_credentials()
354 if has_cert:
355 self._ssl_credentials = grpc.ssl_channel_credentials(
356 certificate_chain=cert, private_key=key
357 )
358 else:
359 self._ssl_credentials = grpc.ssl_channel_credentials()
360 self._is_mtls = False
361 except (exceptions.ClientCertError, OSError) as caught_exc:
362 new_exc = exceptions.MutualTLSChannelError(caught_exc)
363 raise new_exc from caught_exc
364 else:
365 self._ssl_credentials = grpc.ssl_channel_credentials()
367 return self._ssl_credentials
369 @property
370 def is_mtls(self):
371 """Indicates if the created SSL channel credentials is mutual TLS."""
372 return self._is_mtls