ceph/doc/radosgw/STS.rst

   1 ===========
   2 STS in Ceph
   3 ===========
   4
   5 Secure Token Service is a web service in AWS that returns a set of temporary security credentials for authenticating federated users.
   6 The link to official AWS documentation can be found here: https://docs.aws.amazon.com/STS/latest/APIReference/Welcome.html.
   7
   8 Ceph Object Gateway implements a subset of STS APIs that provide temporary credentials for identity and access management.
   9 These temporary credentials can be used to make subsequent S3 calls which will be authenticated by the STS engine in Ceph Object Gateway.
  10 Permissions of the temporary credentials can be further restricted via an IAM policy passed as a parameter to the STS APIs.
  11
  12 STS REST APIs
  13 =============
  14
  15 The following STS REST APIs have been implemented in Ceph Object Gateway:
  16
  17 1. AssumeRole: Returns a set of temporary credentials that can be used for
  18 cross-account access. The temporary credentials will have permissions that are
  19 allowed by both - permission policies attached with the Role and policy attached
  20 with the AssumeRole API.
  21
  22 Parameters:
  23     **RoleArn** (String/ Required): ARN of the Role to Assume.
  24
  25     **RoleSessionName** (String/ Required): An Identifier for the assumed role
  26     session.
  27
  28     **Policy** (String/ Optional): An IAM Policy in JSON format.
  29
  30     **DurationSeconds** (Integer/ Optional): The duration in seconds of the session.
  31     Its default value is 3600.
  32
  33     **ExternalId** (String/ Optional): A unique Id that might be used when a role is
  34     assumed in another account.
  35
  36     **SerialNumber** (String/ Optional): The Id number of the MFA device associated
  37     with the user making the AssumeRole call.
  38
  39     **TokenCode** (String/ Optional): The value provided by the MFA device, if the
  40     trust policy of the role being assumed requires MFA.
  41
  42 2. AssumeRoleWithWebIdentity: Returns a set of temporary credentials for users that
  43 have been authenticated by a web/mobile app by an OpenID Connect /OAuth2.0 Identity Provider.
  44 Currently Keycloak has been tested and integrated with RGW.
  45
  46 Parameters:
  47     **RoleArn** (String/ Required): ARN of the Role to Assume.
  48
  49     **RoleSessionName** (String/ Required): An Identifier for the assumed role
  50     session.
  51
  52     **Policy** (String/ Optional): An IAM Policy in JSON format.
  53
  54     **DurationSeconds** (Integer/ Optional): The duration in seconds of the session.
  55     Its default value is 3600.
  56
  57     **ProviderId** (String/ Optional): Fully qualified host component of the domain name
  58     of the IDP. Valid only for OAuth2.0 tokens (not for OpenID Connect tokens).
  59
  60     **WebIdentityToken** (String/ Required): The OpenID Connect/ OAuth2.0 token, which the
  61     application gets in return after authenticating its user with an IDP.
  62
  63 Before invoking AssumeRoleWithWebIdentity, an OpenID Connect Provider entity (which the web application
  64 authenticates with), needs to be created in RGW.
  65
  66 The trust between the IDP and the role is created by adding a condition to the role's trust policy, which
  67 allows access only to applications which satisfy the given condition.
  68 All claims of the JWT are supported in the condition of the role's trust policy.
  69 An example of a policy that uses the 'aud' claim in the condition is of the form::
  70
  71     '''{"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>"}}}]}'''
  72
  73 The app_id in the condition above must match the 'aud' claim of the incoming token.
  74
  75 An example of a policy that uses the 'sub' claim in the condition is of the form::
  76
  77     "{\"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>\"\}\}\}\]\}"
  78
  79 Similarly, an example of a policy that uses 'azp' claim in the condition is of the form::
  80
  81     "{\"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>\"\}\}\}\]\}"
  82
  83 A shadow user is created corresponding to every federated user. The user id is derived from the 'sub' field of the incoming web token.
  84 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
  85 is - <tenant>$<user-namespace>$<sub> where user-namespace is 'oidc' for users that authenticate with oidc providers.
  86
  87 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
  88 :doc:`session-tags`.
  89
  90 STS Configuration
  91 =================
  92
  93 The following configurable options have to be added for STS integration::
  94
  95   [client.radosgw.gateway]
  96   rgw sts key = {sts key for encrypting the session token}
  97   rgw s3 auth use sts = true
  98
  99 Note: By default, STS and S3 APIs co-exist in the same namespace, and both S3
 100 and STS APIs can be accessed via the same endpoint in Ceph Object Gateway.
 101
 102 Examples
 103 ========
 104
 105 1. The following is an example of AssumeRole API call, which shows steps to create a role, assign a policy to it
 106 (that allows access to S3 resources), assuming a role to get temporary credentials and accessing s3 resources using
 107 those credentials. In this example, TESTER1 assumes a role created by TESTER, to access S3 resources owned by TESTER,
 108 according to the permission policy attached to the role.
 109
 110 .. code-block:: python
 111
 112     import boto3
 113
 114     iam_client = boto3.client('iam',
 115     aws_access_key_id=<access_key of TESTER>,
 116     aws_secret_access_key=<secret_key of TESTER>,
 117     endpoint_url=<IAM URL>,
 118     region_name=''
 119     )
 120
 121     policy_document = '''{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Principal":{"AWS":["arn:aws:iam:::user/TESTER1"]},"Action":["sts:AssumeRole"]}]}'''
 122
 123     role_response = iam_client.create_role(
 124     AssumeRolePolicyDocument=policy_document,
 125     Path='/',
 126     RoleName='S3Access',
 127     )
 128
 129     role_policy = '''{"Version":"2012-10-17","Statement":{"Effect":"Allow","Action":"s3:*","Resource":"arn:aws:s3:::*"}}'''
 130
 131     response = iam_client.put_role_policy(
 132     RoleName='S3Access',
 133     PolicyName='Policy1',
 134     PolicyDocument=role_policy
 135     )
 136
 137     sts_client = boto3.client('sts',
 138     aws_access_key_id=<access_key of TESTER1>,
 139     aws_secret_access_key=<secret_key of TESTER1>,
 140     endpoint_url=<STS URL>,
 141     region_name='',
 142     )
 143
 144     response = sts_client.assume_role(
 145     RoleArn=role_response['Role']['Arn'],
 146     RoleSessionName='Bob',
 147     DurationSeconds=3600
 148     )
 149
 150     s3client = boto3.client('s3',
 151     aws_access_key_id = response['Credentials']['AccessKeyId'],
 152     aws_secret_access_key = response['Credentials']['SecretAccessKey'],
 153     aws_session_token = response['Credentials']['SessionToken'],
 154     endpoint_url=<S3 URL>,
 155     region_name='',)
 156
 157     bucket_name = 'my-bucket'
 158     s3bucket = s3client.create_bucket(Bucket=bucket_name)
 159     resp = s3client.list_buckets()
 160
 161 2. The following is an example of AssumeRoleWithWebIdentity API call, where an external app that has users authenticated with
 162 an OpenID Connect/ OAuth2 IDP (Keycloak in this example), assumes a role to get back temporary credentials and access S3 resources
 163 according to permission policy of the role.
 164
 165 .. code-block:: python
 166
 167     import boto3
 168
 169     iam_client = boto3.client('iam',
 170     aws_access_key_id=<access_key of TESTER>,
 171     aws_secret_access_key=<secret_key of TESTER>,
 172     endpoint_url=<IAM URL>,
 173     region_name=''
 174     )
 175
 176     oidc_response = iam_client.create_open_id_connect_provider(
 177         Url=<URL of the OpenID Connect Provider,
 178         ClientIDList=[
 179             <Client id registered with the IDP>
 180         ],
 181         ThumbprintList=[
 182             <Thumbprint of the IDP>
 183      ]
 184     )
 185
 186     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"}}}]}'''
 187     role_response = iam_client.create_role(
 188     AssumeRolePolicyDocument=policy_document,
 189     Path='/',
 190     RoleName='S3Access',
 191     )
 192
 193     role_policy = '''{"Version":"2012-10-17","Statement":{"Effect":"Allow","Action":"s3:*","Resource":"arn:aws:s3:::*"}}'''
 194
 195     response = iam_client.put_role_policy(
 196         RoleName='S3Access',
 197         PolicyName='Policy1',
 198         PolicyDocument=role_policy
 199     )
 200
 201     sts_client = boto3.client('sts',
 202     aws_access_key_id=<access_key of TESTER1>,
 203     aws_secret_access_key=<secret_key of TESTER1>,
 204     endpoint_url=<STS URL>,
 205     region_name='',
 206     )
 207
 208     response = client.assume_role_with_web_identity(
 209     RoleArn=role_response['Role']['Arn'],
 210     RoleSessionName='Bob',
 211     DurationSeconds=3600,
 212     WebIdentityToken=<Web Token>
 213     )
 214
 215     s3client = boto3.client('s3',
 216     aws_access_key_id = response['Credentials']['AccessKeyId'],
 217     aws_secret_access_key = response['Credentials']['SecretAccessKey'],
 218     aws_session_token = response['Credentials']['SessionToken'],
 219     endpoint_url=<S3 URL>,
 220     region_name='',)
 221
 222     bucket_name = 'my-bucket'
 223     s3bucket = s3client.create_bucket(Bucket=bucket_name)
 224     resp = s3client.list_buckets()
 225
 226 How to obtain thumbprint of an OpenID Connect Provider IDP
 227 ==========================================================
 228 1. Take the OpenID connect provider's URL and add /.well-known/openid-configuration
 229 to it to get the URL to get the IDP's configuration document. For example, if the URL
 230 of the IDP is http://localhost:8000/auth/realms/quickstart, then the URL to get the
 231 document from is http://localhost:8000/auth/realms/quickstart/.well-known/openid-configuration
 232
 233 2. Use the following curl command to get the configuration document from the URL described
 234 in step 1::
 235
 236     curl -k -v \
 237       -X GET \
 238       -H "Content-Type: application/x-www-form-urlencoded" \
 239       "http://localhost:8000/auth/realms/quickstart/.well-known/openid-configuration" \
 240     | jq .
 241
 242  3. From the response of step 2, use the value of "jwks_uri" to get the certificate of the IDP,
 243  using the following code::
 244      curl -k -v \
 245       -X GET \
 246       -H "Content-Type: application/x-www-form-urlencoded" \
 247       "http://$KC_SERVER/$KC_CONTEXT/realms/$KC_REALM/protocol/openid-connect/certs" \
 248       | jq .
 249
 250 3. Copy the result of "x5c" in the response above, in a file certificate.crt, and add
 251 '-----BEGIN CERTIFICATE-----' at the beginning and "-----END CERTIFICATE-----"
 252 at the end.
 253
 254 4. Use the following OpenSSL command to get the certificate thumbprint::
 255
 256     openssl x509 -in certificate.crt -fingerprint -noout
 257
 258 5. The result of the above command in step 4, will be a SHA1 fingerprint, like the following::
 259
 260     SHA1 Fingerprint=F7:D7:B3:51:5D:D0:D3:19:DD:21:9A:43:A9:EA:72:7A:D6:06:52:87
 261
 262 6.  Remove the colons from the result above to get the final thumbprint which can be as input
 263 while creating the OpenID Connect Provider entity in IAM::
 264
 265     F7D7B3515DD0D319DD219A43A9EA727AD6065287
 266
 267 Roles in RGW
 268 ============
 269
 270 More information for role manipulation can be found here
 271 :doc:`role`.
 272
 273 OpenID Connect Provider in RGW
 274 ==============================
 275
 276 More information for OpenID Connect Provider entity manipulation
 277 can be found here
 278 :doc:`oidc`.
 279
 280 Keycloak integration with Radosgw
 281 =================================
 282
 283 Steps for integrating Radosgw with Keycloak can be found here
 284 :doc:`keycloak`.
 285
 286 STSLite
 287 =======
 288 STSLite has been built on STS, and documentation for the same can be found here
 289 :doc:`STSLite`.