Certificate Attribute Mapping

IAM Roles Anywhere provides you with the capability to define a custom set of mapping rules, enabling you to specify which data are extracted from authenticating certificates as session tags for authorization policies. These customized attribute mappings are associated with a profile.

The data elements are referred as attributes and can be sourced from known resource from the certificate. Specifiers are used to represent one or more attributes.

Default Mapping Behavior

The following attributes are mapped by default when you create a profile. The default mapping rules are as follows:

• x509Subject: maps all supported Relative Distinguished Names (RDNs) from an authenticating certificate's Subject into distinct PrincipalTag elements in the session.

• x509Issuer: maps all supported Relative Distinguished Names (RDNs) from an authenticating certificate's Issuer into distinct PrincipalTag elements in the session.

• x509SAN (Subject Alternative Name): maps the first value of the following types: DNS Names, Directory Name (DN), and URI Names

To view your current mappings associated with a profile, using the following command:

$aws rolesanywhere get-profile --profile-id PROFILE_ID

Default mapping rules in a JSON format:

"attributeMappings": [
  {
    "mappingRules": [
        {
            "specifier": "*"
        }
    ],
    "certificateField": "x509Issuer"
  },
  {
    "mappingRules": [
        {
            "specifier": "DNS"
        },
        {
            "specifier": "URI"
        },
        {
            "specifier": "Name/*"
        }
    ],
    "certificateField": "x509SAN"
  },
  {
    "mappingRules": [
        {
            "specifier": "*"
        }
    ],
    "certificateField": "x509Subject"
  }
]

Note

If you see * as a specifier, it signifies the default behavior, which maps all recognizable RDNs for x509Subject, x509Issuer and x509SAN/Name. However, * does not have a defined behavior in the context of x509SAN/URI, x509SAN/DNS, or x509SAN/. The specifier Name/ represents the first recognizable attribute of the Directory Name. Both Name and Name/ are equivalent to Name/* and will be displayed as Name/*in the mapping rule.

Put attribute mappings (command line interface)

put-attribute-mapping enables you to attach new mapping rules to your profile. When using that profile, the certificate mapping behavior changes according to your customized rules.

To put a mapping rule, using the following command:

$aws rolesanywhere put-attribute-mapping \
        --certificate-field CERTIFICATE_FIELD \
        --mapping-rules specifier=SPECIFIER \
        --profile-id PROFILE_ID

The CERTIFICATE_FIELD can be in one of x509Subject, x509Issuer and x509SAN. The SPECIFIER is a string enforced by a standard (e.g., OID) that can map to a piece of information encoded in the certificate.

For example, to add mapping rules for x509Subject/CN and x509Subject/OU, use the following command:

$aws rolesanywhere put-attribute-mapping \
        --certificate-field x509Subject \
        --mapping-rules specifier=CN specifier=OU \
        --profile-id PROFILE_ID

Put attribute mappings (console)

1. Sign in to IAM Roles Anywhere console .

2. Scroll to find profile table and choose the profile to add certificate attribute mappings.

3. Within profile detail page scroll towards Certificate attribute mappings section and choose Manage mappings.

4. Scroll to find the Add mappings button and click on it.

5. Choose a certificate field from either Subject, Issuer, or Subject Alternative Name in the dropdown list, and enter the specifier

6. Select Save changes to add attribute mappings.

Delete attribute mappings (command line interface)

delete-attribute-mapping enables you to delete mapping rules from your profile. When using that profile, the attribute specified by the deleted mapping rule will not be mapped from a certificate.

To delete a mapping rule, using the following command:

$aws rolesanywhere delete-attribute-mapping \
        --certificate-field CERTIFICATE_FIELD \
        --specifiers SPECIFIERS \
        --profile-id PROFILE_ID

The CERTIFICATE_FIELD can be in one of x509Subject, x509Issuer and x509SAN. The SPECIFIER is a string enforced by a standard (e.g., OID) that exists in your current mapping rules.

For example, to delete mapping rules for x509Subject/CN and x509Subject/OU, use the following command:

$aws rolesanywhere delete-attribute-mapping \
        --certificate-field x509Subject \
        --specifiers CN OU \
        --profile-id PROFILE_ID

Delete attribute mappings (console)

1. Sign in to IAM Roles Anywhere console .

2. Scroll to find profile table and choose the profile to remove certificate attribute mappings.

3. Within profile detail page scroll towards Certificate attribute mappings section and choose Manage mappings.

4. Scroll to find the corresponding attribute mapping row and click on Remove mapping button associated with it.

5. Select Save changes to remove attribute mappings.

Attribute mapping and trust policy

It is recommended to have condition statements in the Assume Role Policy Document to restrict authorization based on attributes that are extracted from an end-entity X.509 certificate. For more information about the role trust policy, see Trust policy.

The attribute mapping field of a profile controls which attributes from an authenticating X.509 certificate will be mapped for principal tags. Therefore, while adding condition statements to an Assume Role Policy Document, be cautious that the specifiers used in mapping rules for authorization need to be mapped accordingly.

The following example shows trust policies that add a condition based on the Issuer Common Name (CN) of the certificate.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "rolesanywhere.amazonaws.com"
      },
      "Action": [
        "sts:AssumeRole",
        "sts:TagSession",
        "sts:SetSourceIdentity"
      ],
      "Condition": {
        "StringEquals": {
          "aws:PrincipalTag/x509Issuer/CN": "Bob"
        },
        "ArnEquals": {
          "aws:SourceArn": [
            "arn:aws:rolesanywhere:region:account:trust-anchor/TA_ID"
          ]
        }
      }
    }
  ]
}

If a profile is used with an Attribute Mapping field that lacks specifier: CN or specifier: * in the mappingRules for x509Issuer, the first condition in the Assume Role Policy Document will evaluate as false because there will be no value mapped aws:PrincipalTag/x509Issuer/CN.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "rolesanywhere.amazonaws.com"
      },
      "Action": [
        "sts:AssumeRole",
        "sts:TagSession",
        "sts:SetSourceIdentity"
      ],
      "Condition": {
        "StringNotEquals": {
          "aws:PrincipalTag/x509Issuer/CN": "Bob"
        },
        "ArnEquals": {
          "aws:SourceArn": [
            "arn:aws:rolesanywhere:region:account:trust-anchor/TA_ID"
          ]
        }
      }
    }
  ]
}

Likewise, if the condition is StringNotEquals , the condition will evaluate to true using the same profile. This happens because the condition is disregarded when the principal tag is dropped due to attribute mapping APIs.

Having the Attribute Mapping field provided below in a profile, the StringEquals condition for x509Issuer/CN will assess to false, or the StringNotEquals condition will assess to true.

"attributeMappings": [
  {
    "mappingRules": [
        {
            "specifier": "O"
        }
    ],
    "certificateField": "x509Issuer"
  },
  {
    "mappingRules": [
        {
            "specifier": "DNS"
        },
        {
            "specifier": "URI"
        },
        {
            "specifier": "Name/*"
        }
    ],
    "certificateField": "x509SAN"
  },
  {
    "mappingRules": [
        {
            "specifier": "*"
        }
    ],
    "certificateField": "x509Subject"
  }
]