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297 lines
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ReStructuredText
297 lines
12 KiB
ReStructuredText
===========
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STS in Ceph
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===========
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Secure Token Service is a web service in AWS that returns a set of temporary security credentials for authenticating federated users.
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The link to official AWS documentation can be found here: https://docs.aws.amazon.com/STS/latest/APIReference/Welcome.html.
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Ceph Object Gateway implements a subset of STS APIs that provide temporary credentials for identity and access management.
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These temporary credentials can be used to make subsequent S3 calls which will be authenticated by the STS engine in Ceph Object Gateway.
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Permissions of the temporary credentials can be further restricted via an IAM policy passed as a parameter to the STS APIs.
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STS REST APIs
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=============
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The following STS REST APIs have been implemented in Ceph Object Gateway:
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1. AssumeRole: Returns a set of temporary credentials that can be used for
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cross-account access. The temporary credentials will have permissions that are
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allowed by both - permission policies attached with the Role and policy attached
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with the AssumeRole API.
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Parameters:
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**RoleArn** (String/ Required): ARN of the Role to Assume.
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**RoleSessionName** (String/ Required): An Identifier for the assumed role
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session.
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**Policy** (String/ Optional): An IAM Policy in JSON format.
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**DurationSeconds** (Integer/ Optional): The duration in seconds of the session.
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Its default value is 3600.
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**ExternalId** (String/ Optional): A unique Id that might be used when a role is
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assumed in another account.
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**SerialNumber** (String/ Optional): The Id number of the MFA device associated
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with the user making the AssumeRole call.
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**TokenCode** (String/ Optional): The value provided by the MFA device, if the
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trust policy of the role being assumed requires MFA.
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2. AssumeRoleWithWebIdentity: Returns a set of temporary credentials for users that
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have been authenticated by a web/mobile app by an OpenID Connect /OAuth2.0 Identity Provider.
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Currently Keycloak has been tested and integrated with RGW.
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Parameters:
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**RoleArn** (String/ Required): ARN of the Role to Assume.
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**RoleSessionName** (String/ Required): An Identifier for the assumed role
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session.
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**Policy** (String/ Optional): An IAM Policy in JSON format.
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**DurationSeconds** (Integer/ Optional): The duration in seconds of the session.
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Its default value is 3600.
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**ProviderId** (String/ Optional): Fully qualified host component of the domain name
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of the IDP. Valid only for OAuth2.0 tokens (not for OpenID Connect tokens).
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**WebIdentityToken** (String/ Required): The OpenID Connect/ OAuth2.0 token, which the
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application gets in return after authenticating its user with an IDP.
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Before invoking AssumeRoleWithWebIdentity, an OpenID Connect Provider entity (which the web application
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authenticates with), needs to be created in RGW.
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The trust between the IDP and the role is created by adding a condition to the role's trust policy, which
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allows access only to applications which satisfy the given condition.
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All claims of the JWT are supported in the condition of the role's trust policy.
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An example of a policy that uses the 'aud' claim in the condition is of the form::
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'''{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Principal":{"Federated":["arn:aws:iam:::oidc-provider/<URL of IDP>"]},"Action":["sts:AssumeRoleWithWebIdentity"],"Condition":{"StringEquals":{"<URL of IDP> :app_id":"<aud>"}}}]}'''
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The app_id in the condition above must match the 'aud' claim of the incoming token.
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An example of a policy that uses the 'sub' claim in the condition is of the form::
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"{\"Version\":\"2012-10-17\",\"Statement\":[{\"Effect\":\"Allow\",\"Principal\":{\"Federated\":[\"arn:aws:iam:::oidc-provider/<URL of IDP>\"]},\"Action\":[\"sts:AssumeRoleWithWebIdentity\"],\"Condition\":{\"StringEquals\":{\"<URL of IDP> :sub\":\"<sub>\"\}\}\}\]\}"
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Similarly, an example of a policy that uses 'azp' claim in the condition is of the form::
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"{\"Version\":\"2012-10-17\",\"Statement\":[{\"Effect\":\"Allow\",\"Principal\":{\"Federated\":[\"arn:aws:iam:::oidc-provider/<URL of IDP>\"]},\"Action\":[\"sts:AssumeRoleWithWebIdentity\"],\"Condition\":{\"StringEquals\":{\"<URL of IDP> :azp\":\"<azp>\"\}\}\}\]\}"
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A shadow user is created corresponding to every federated user. The user id is derived from the 'sub' field of the incoming web token.
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The user is created in a separate namespace - 'oidc' such that the user id doesn't clash with any other user ids in rgw. The format of the user id
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is - <tenant>$<user-namespace>$<sub> where user-namespace is 'oidc' for users that authenticate with oidc providers.
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RGW now supports Session tags that can be passed in the web token to AssumeRoleWithWebIdentity call. More information related to Session Tags can be found here
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:doc:`session-tags`.
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STS Configuration
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=================
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The following configurable options have to be added for STS integration::
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[client.{your-rgw-name}]
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rgw_sts_key = {sts key for encrypting the session token}
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rgw_s3_auth_use_sts = true
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Notes:
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* By default, STS and S3 APIs co-exist in the same namespace, and both S3
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and STS APIs can be accessed via the same endpoint in Ceph Object Gateway.
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* The ``rgw_sts_key`` needs to be a hex-string consisting of exactly 16 characters.
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Examples
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========
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1. In order to get the example to work, make sure that the user TESTER has the ``roles`` capability assigned:
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.. code-block:: console
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radosgw-admin caps add --uid="TESTER" --caps="roles=*"
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2. The following is an example of the AssumeRole API call, which shows steps to create a role, assign a policy to it
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(that allows access to S3 resources), assuming a role to get temporary credentials and accessing S3 resources using
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those credentials. In this example, TESTER1 assumes a role created by TESTER, to access S3 resources owned by TESTER,
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according to the permission policy attached to the role.
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.. code-block:: python
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import boto3
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iam_client = boto3.client('iam',
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aws_access_key_id=<access_key of TESTER>,
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aws_secret_access_key=<secret_key of TESTER>,
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endpoint_url=<IAM URL>,
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region_name=''
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)
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policy_document = '''{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Principal":{"AWS":["arn:aws:iam:::user/TESTER1"]},"Action":["sts:AssumeRole"]}]}'''
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role_response = iam_client.create_role(
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AssumeRolePolicyDocument=policy_document,
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Path='/',
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RoleName='S3Access',
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)
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role_policy = '''{"Version":"2012-10-17","Statement":{"Effect":"Allow","Action":"s3:*","Resource":"arn:aws:s3:::*"}}'''
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response = iam_client.put_role_policy(
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RoleName='S3Access',
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PolicyName='Policy1',
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PolicyDocument=role_policy
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)
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sts_client = boto3.client('sts',
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aws_access_key_id=<access_key of TESTER1>,
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aws_secret_access_key=<secret_key of TESTER1>,
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endpoint_url=<STS URL>,
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region_name='',
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)
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response = sts_client.assume_role(
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RoleArn=role_response['Role']['Arn'],
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RoleSessionName='Bob',
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DurationSeconds=3600
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)
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s3client = boto3.client('s3',
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aws_access_key_id = response['Credentials']['AccessKeyId'],
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aws_secret_access_key = response['Credentials']['SecretAccessKey'],
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aws_session_token = response['Credentials']['SessionToken'],
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endpoint_url=<S3 URL>,
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region_name='',)
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bucket_name = 'my-bucket'
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s3bucket = s3client.create_bucket(Bucket=bucket_name)
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resp = s3client.list_buckets()
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2. The following is an example of AssumeRoleWithWebIdentity API call, where an external app that has users authenticated with
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an OpenID Connect/ OAuth2 IDP (Keycloak in this example), assumes a role to get back temporary credentials and access S3 resources
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according to permission policy of the role.
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.. code-block:: python
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import boto3
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iam_client = boto3.client('iam',
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aws_access_key_id=<access_key of TESTER>,
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aws_secret_access_key=<secret_key of TESTER>,
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endpoint_url=<IAM URL>,
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region_name=''
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)
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oidc_response = iam_client.create_open_id_connect_provider(
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Url=<URL of the OpenID Connect Provider,
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ClientIDList=[
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<Client id registered with the IDP>
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],
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ThumbprintList=[
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<Thumbprint of the IDP>
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]
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)
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policy_document = '''{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Principal":{"Federated":["arn:aws:iam:::oidc-provider/localhost:8080/auth/realms/demo"]},"Action":["sts:AssumeRoleWithWebIdentity"],"Condition":{"StringEquals":{"localhost:8080/auth/realms/demo:app_id":"customer-portal"}}}]}'''
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role_response = iam_client.create_role(
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AssumeRolePolicyDocument=policy_document,
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Path='/',
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RoleName='S3Access',
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)
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role_policy = '''{"Version":"2012-10-17","Statement":{"Effect":"Allow","Action":"s3:*","Resource":"arn:aws:s3:::*"}}'''
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response = iam_client.put_role_policy(
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RoleName='S3Access',
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PolicyName='Policy1',
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PolicyDocument=role_policy
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)
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sts_client = boto3.client('sts',
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aws_access_key_id=<access_key of TESTER1>,
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aws_secret_access_key=<secret_key of TESTER1>,
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endpoint_url=<STS URL>,
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region_name='',
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)
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response = client.assume_role_with_web_identity(
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RoleArn=role_response['Role']['Arn'],
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RoleSessionName='Bob',
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DurationSeconds=3600,
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WebIdentityToken=<Web Token>
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)
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s3client = boto3.client('s3',
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aws_access_key_id = response['Credentials']['AccessKeyId'],
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aws_secret_access_key = response['Credentials']['SecretAccessKey'],
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aws_session_token = response['Credentials']['SessionToken'],
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endpoint_url=<S3 URL>,
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region_name='',)
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bucket_name = 'my-bucket'
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s3bucket = s3client.create_bucket(Bucket=bucket_name)
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resp = s3client.list_buckets()
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How to obtain thumbprint of an OpenID Connect Provider IDP
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==========================================================
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1. Take the OpenID connect provider's URL and add /.well-known/openid-configuration
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to it to get the URL to get the IDP's configuration document. For example, if the URL
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of the IDP is http://localhost:8000/auth/realms/quickstart, then the URL to get the
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document from is http://localhost:8000/auth/realms/quickstart/.well-known/openid-configuration
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2. Use the following curl command to get the configuration document from the URL described
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in step 1::
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curl -k -v \
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-X GET \
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-H "Content-Type: application/x-www-form-urlencoded" \
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"http://localhost:8000/auth/realms/quickstart/.well-known/openid-configuration" \
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| jq .
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3. From the response of step 2, use the value of "jwks_uri" to get the certificate of the IDP,
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using the following code::
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curl -k -v \
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-X GET \
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-H "Content-Type: application/x-www-form-urlencoded" \
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"http://$KC_SERVER/$KC_CONTEXT/realms/$KC_REALM/protocol/openid-connect/certs" \
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| jq .
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3. Copy the result of "x5c" in the response above, in a file certificate.crt, and add
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'-----BEGIN CERTIFICATE-----' at the beginning and "-----END CERTIFICATE-----"
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at the end.
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4. Use the following OpenSSL command to get the certificate thumbprint::
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openssl x509 -in certificate.crt -fingerprint -noout
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5. The result of the above command in step 4, will be a SHA1 fingerprint, like the following::
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SHA1 Fingerprint=F7:D7:B3:51:5D:D0:D3:19:DD:21:9A:43:A9:EA:72:7A:D6:06:52:87
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6. Remove the colons from the result above to get the final thumbprint which can be as input
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while creating the OpenID Connect Provider entity in IAM::
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F7D7B3515DD0D319DD219A43A9EA727AD6065287
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Roles in RGW
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============
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More information for role manipulation can be found here
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:doc:`role`.
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OpenID Connect Provider in RGW
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==============================
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More information for OpenID Connect Provider entity manipulation
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can be found here
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:doc:`oidc`.
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Keycloak integration with Radosgw
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=================================
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Steps for integrating Radosgw with Keycloak can be found here
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:doc:`keycloak`.
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STSLite
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=======
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STSLite has been built on STS, and documentation for the same can be found here
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:doc:`STSLite`. |