Grant self-managed permissions

This topic provides instructions on how to create the IAM service roles required by StackSets to deploy across accounts and AWS Regions with self-managed permissions. These roles are necessary to establish a trusted relationship between the account you're administering the stack set from and the account you're deploying stack instances to. Using this permissions model, StackSets can deploy to any AWS account in which you have permissions to create an IAM role.

To use service-managed permissions, see Activate trusted access instead.

Self-managed permissions overview

Before you create a stack set with self-managed permissions, you must have created IAM service roles in each account.

The basic steps are:

1. Determine which AWS account is the administrator account.

   Stack sets are created in this administrator account. A target account is the account in which you create individual stacks that belong to a stack set.

2. Determine how you want to structure permissions for the stack set.

   The simplest (and most permissive) permissions configuration is where you give all users and groups in the administrator account the ability to create and update all the stack sets managed through that account. If you need finer-grained control, you can set up permissions to specify:

   • Which users and groups can perform stack set operations in which target accounts.

   • Which resources users and groups can include in their stack sets.

   • Which stack set operations specific users and groups can perform.

3. Create the necessary IAM service roles in your administrator and target accounts to define the permissions you want.

   Specifically, the two required roles are:

   • AWSCloudFormationStackSetAdministrationRole – This role is deployed to the administrator account.

   • AWSCloudFormationStackSetExecutionRole – This role is deployed to all accounts where you create stack instances.

Give all users of the administrator account permissions to manage stacks in all target accounts

This section shows you how to set up permissions to allow all users and groups of the administrator account to perform stack set operations in all target accounts. It guides you through creating the required IAM service roles in your administrator and target accounts. Anyone in the administrator account can then create, update, or delete any stacks across any of the target accounts.

By structuring permissions in this manner, users don't pass an administration role when creating or updating a stack set.

Administrator account

In the administrator account, create an IAM role named AWSCloudFormationStackSetAdministrationRole.

You can do this by creating a stack from the CloudFormation template available from https://s3.amazonaws.com/cloudformation-stackset-sample-templates-us-east-1/AWSCloudFormationStackSetAdministrationRole.yml.

Example permissions policy

The administration role created by the preceding template includes the following permissions policy.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": [
        "sts:AssumeRole"
      ],
      "Resource": [
        "arn:aws:iam::*:role/AWSCloudFormationStackSetExecutionRole"
      ],
      "Effect": "Allow"
    }
  ]
}

Example trust policy 1

The preceding template also includes the following trust policy that grants the service permission to use the administration role and the permissions attached to the role.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "cloudformation.amazonaws.com"
      },
      "Action": "sts:AssumeRole"
    }
  ]
}

Example trust policy 2

To deploy stack instances into a target account that resides in a Region that's disabled by default, you must also include the regional service principal for that Region. Each Region that's disabled by default will have its own regional service principal.

The following example trust policy grants the service permission to use the administration role in the Asia Pacific (Hong Kong) Region (ap-east-1), a Region that's disabled by default.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": [
            "cloudformation.amazonaws.com",
            "cloudformation.ap-east-1.amazonaws.com"
         ]
      },
      "Action": "sts:AssumeRole"
    }
  ]
}

For more information, see Prepare to perform stack set operations in AWS Regions that are disabled by default. For a list of Region codes, see Regional endpoints in the AWS General Reference Guide.

Target accounts

In each target account, create a service role named AWSCloudFormationStackSetExecutionRole that trusts the administrator account. The role must have this exact name. You can do this by creating a stack from the CloudFormation template available from https://s3.amazonaws.com/cloudformation-stackset-sample-templates-us-east-1/AWSCloudFormationStackSetExecutionRole.yml. When you use this template, you are prompted to provide the account ID of the administrator account with which your target account must have a trust relationship.

Important

Be aware that this template grants administrator access. After you use the template to create a target account execution role, you must scope the permissions in the policy statement to the types of resources that you are creating by using StackSets.

The target account service role requires permissions to perform any operations that are specified in your CloudFormation template. For example, if your template is creating an S3 bucket, then you need permissions to create new objects for S3. Your target account always needs full CloudFormation permissions, which include permissions to create, update, delete, and describe stacks.

Example permissions policy 1

The role created by this template enables the following policy on a target account.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "*",
      "Resource": "*"
    }
  ]
}

Example permissions policy 2

The following example shows a policy statement with the minimum permissions for StackSets to work. To create stacks in target accounts that use resources from services other than CloudFormation, you must add those service actions and resources to the AWSCloudFormationStackSetExecutionRole policy statement for each target account.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
         "cloudformation:*"
      ],
      "Resource": "*"
    }
  ]
}

Example trust policy

The following trust relationship is created by the template. The administrator account's ID is shown as admin_account_id.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "AWS": "arn:aws:iam::admin_account_id:root"
      },
      "Action": "sts:AssumeRole"
    }
  ]
}

You can configure the trust relationship of an existing target account execution role to trust a specific role in the administrator account. If you delete the role in the administrator account, and create a new one to replace it, you must configure your target account trust relationships with the new administrator account role, represented by admin_account_id in the preceding example.

Set up advanced permissions options for stack set operations

If you require finer-grained control over the stack sets that users and groups are creating through a single administrator account, you can use IAM roles to specify:

• Which users and groups can perform stack set operations in which target accounts.

• Which resources users and groups can include in their stack sets.

• Which stack set operations specific users and groups can perform.

Control which users can perform stack set operations in specific target accounts

Use customized administration roles to control which users and groups can perform stack set operations in which target accounts. You might want to control which users of the administrator account can perform stack set operations in which target accounts. To do this, you create a trust relationship between each target account and a specific customized administration role, rather than creating the AWSCloudFormationStackSetAdministrationRole service role in the administrator account itself. You then activate specific users and groups to use the customized administration role when performing stack set operations in a specific target account.

For example, you can create Role A and Role B within your administrator account. You can give Role A permissions to access target account 1 through account 8. You can give Role B permissions to access target account 9 through account 16.

Setting up the necessary permissions involves defining a customized administration role, creating a service role for the target account, and granting users permission to pass the customized administration role when performing stack set operations.

In general, here's how it works once you have the necessary permissions in place: When creating a stack set, the user must specify a customized administration role. The user must have permission to pass the role to CloudFormation. In addition, the customized administration role must have a trust relationship with the target accounts specified for the stack set. CloudFormation creates the stack set and associates the customized administration role with it. When updating a stack set, the user must explicitly specify a customized administration role, even if it's the same customized administration role used with this stack set previously. CloudFormation uses that role to update the stack, subject to the requirements above.

Administrator account

Example permissions policy

For each stack set, create a customized administration role with permissions to assume the target account execution role.

The target account execution role name must be the same in every target account. If the role name is AWSCloudFormationStackSetExecutionRole, StackSets uses it automatically when creating a stack set. If you specify a custom role name, users must provide the execution role name when creating a stack set.

Create an IAM service role with a custom name and the following permissions policy. In the examples below, custom_execution_role refers to the execution role in the target accounts.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": [
        "sts:AssumeRole"
      ],
      "Resource": [
        "arn:aws:iam::target_account_id:role/custom_execution_role"
      ],
      "Effect": "Allow"
    }
  ]
}

To specify multiple accounts in a single statement, separate them with commas.

"Resource": [
  "arn:aws:iam::target_account_id_1:role/custom_execution_role", 
  "arn:aws:iam::target_account_id_2:role/custom_execution_role"
]

You can specify all target accounts by using a wildcard (*) instead of an account ID.

"Resource": [
  "arn:aws:iam::*:role/custom_execution_role"
]

Example trust policy 1

You must provide a trust policy for the service role to defines which IAM principals can assume the role.

{ 
  "Version": "2012-10-17", 
  "Statement": [ 
    { 
      "Effect": "Allow", 
      "Principal": { 
        "Service": "cloudformation.amazonaws.com" 
      }, 
      "Action": "sts:AssumeRole" 
    } 
  ] 
}

Example trust policy 2

To deploy stack instances into a target account that resides in a Region that's disabled by default, you must also include the regional service principal for that Region. Each Region that's disabled by default will have its own regional service principal.

The following example trust policy grants the service permission to use the administration role in the Asia Pacific (Hong Kong) Region (ap-east-1), a Region that's disabled by default.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": [
            "cloudformation.amazonaws.com",
            "cloudformation.ap-east-1.amazonaws.com"
         ]
      },
      "Action": "sts:AssumeRole"
    }
  ]
}

For more information, see Prepare to perform stack set operations in AWS Regions that are disabled by default. For a list of Region codes, see Regional endpoints in the AWS General Reference Guide.

Example pass role policy

You also need an IAM permissions policy for your IAM users that allows the user to pass the customized administration role when performing stack set operations. For more information, see Granting a user permissions to pass a role to an AWS service.

In the example below, customized_admin_role refers to the administration role the user needs to pass.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "iam:GetRole",
        "iam:PassRole"
      ],
      "Resource": "arn:aws:iam::*:role/customized_admin_role"
    }
  ]
}

Target accounts

In each target account, create a service role that trusts the customized administration role you want to use with this account.

The target account role requires permissions to perform any operations that are specified in your CloudFormation template. For example, if your template is creating an S3 bucket, then you need permissions to create new objects in S3. Your target account always needs full CloudFormation permissions, which include permissions to create, update, delete, and describe stacks.

The target account role name must be the same in every target account. If the role name is AWSCloudFormationStackSetExecutionRole, StackSets uses it automatically when creating a stack set. If you specify a custom role name, users must provide the execution role name when creating a stack set.

Example permissions policy

The following example shows a policy statement with the minimum permissions for StackSets to work. To create stacks in target accounts that use resources from services other than CloudFormation, you must add those service actions and resources to the permissions policy.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "cloudformation:*"
      ],
      "Resource": "*"
    }
  ]
}

Example trust policy

You must provide the following trust policy when you create the role to define the trust relationship.

{
  "Version": "2012-10-17", 
  "Statement": [ 
    { 
      "Effect": "Allow", 
      "Principal": { 
      "AWS": "arn:aws:iam::admin_account_id:role/customized_admin_role" 
      }, 
      "Action": "sts:AssumeRole"
    } 
  ] 
} 

Control the resources that users can include in specific stack sets

Use customized execution roles to control which stack resources users and groups can include in their stack sets. For example, you might want to set up a group that can only include Amazon S3-related resources in the stack sets they create, while another team can only include DynamoDB resources. To do this, you create a trust relationship between the customized administration role for each group and a customized execution role for each set of resources. The customized execution role defines which stack resources can be included in stack sets. The customized administration role resides in the administrator account, while the customized execution role resides in each target account in which you want to create stack sets using the defined resources. You then activate specific users and groups to use the customized administration role when performing stack set operations.

For example you can create customized administration roles A, B, and C in the administrator account. Users and groups with permission to use Role A can create stack sets containing the stack resources specifically listed in customized execution role X, but not those in roles Y or Z, or resource not included in any execution role.

When updating a stack set, the user must explicitly specify a customized administration role, even if it's the same customized administration role used with this stack set previously. CloudFormation performs the update using the customized administration role specified, so long as the user has permissions to perform operations on that stack set.

Similarly, the user can also specify a customized execution role. If they specify a customized execution role, CloudFormation uses that role to update the stack, subject to the requirements above. If the user doesn't specify a customized execution role, CloudFormation performs the update using the customized execution role previously associated with the stack set, so long as the user has permissions to perform operations on that stack set.

Administrator account

Create a customized administration role in your administrator account, as detailed in Control which users can perform stack set operations in specific target accounts. Include a trust relationship between the customized administration role and the customized execution roles that you want it to use.

Example permissions policy

The following example is a permissions policy for both the AWSCloudFormationStackSetExecutionRole defined for the target account, in addition to a customized execution role.

{
  "Version": "2012-10-17",
   "Statement": [
    {
      "Sid": "Stmt1487980684000",
      "Effect": "Allow",
      "Action": [
        "sts:AssumeRole" 
      ],
      "Resource": [ 
        "arn:aws:iam::*:role/AWSCloudFormationStackSetExecutionRole",
        "arn:aws:iam::*:role/custom_execution_role" 
      ]
    } 
  ]
}

Target accounts

In the target accounts in which you want to create your stack sets, create a customized execution role that grants permissions to the services and resources that you want users and groups to be able to include in the stack sets.

Example permissions policy

The following example provides the minimum permissions for stack sets, along with permission to create Amazon DynamoDB tables.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "cloudformation:*"
      ],
      "Resource": "*"
    },
    {
      "Effect": "Allow",
      "Action": [
        "dynamoDb:createTable"
      ],
      "Resource": "*"
    }
  ]
}

Example trust policy

You must provide the following trust policy when you create the role to define the trust relationship.

{
  "Version": "2012-10-17", 
  "Statement": [ 
    { 
      "Effect": "Allow", 
      "Principal": { 
      "AWS": "arn:aws:iam::admin_account_id:role/customized_admin_role" 
      }, 
      "Action": "sts:AssumeRole"
    } 
  ] 
} 

Set up permissions for specific stack set operations

In addition, you can set up permissions for which user and groups can perform specific stack set operations, such as creating, updating, or deleting stack sets or stack instances. For more information, see Actions, resources, and condition keys for CloudFormation in the Service Authorization Reference.

Set up global keys to mitigate confused deputy problems

The confused deputy problem is a security issue where an entity that doesn't have permission to perform an action can coerce a more-privileged entity to perform the action. In AWS, cross-service impersonation can result in the confused deputy problem. Cross-service impersonation can occur when one service (the calling service) calls another service (the called service). The calling service can be manipulated to use its permissions to act on another customer's resources in a way it shouldn't otherwise have permission to access. To prevent this, AWS provides tools that help you protect your data for all services with service principals that have been given access to resources in your account.

We recommend using the aws:SourceArn and aws:SourceAccount global condition context keys in resource policies to limit the permissions that AWS CloudFormation StackSets gives another service to the resource. If you use both global condition context keys, the aws:SourceAccount value and the account in the aws:SourceArn value must use the same account ID when used in the same policy statement.

The most effective way to protect against the confused deputy problem is to use the aws:SourceArn global condition context key with the full ARN of the resource. If you don't know the full ARN of the resource or if you are specifying multiple resources, use the aws:SourceArn global context condition key with wildcards (*) for the unknown portions of the ARN. For example, arn:aws:cloudformation::123456789012:*. Whenever possible, use aws:SourceArn, because it's more specific. Use aws:SourceAccount only when you can't determine the correct ARN or ARN pattern.

When StackSets assumes the Administration role in your administrator account, StackSets populates your administrator account ID and StackSets Amazon Resource Name (ARN). Therefore, you can define conditions for global keys aws:SourceAccount and aws:SourceArn in the trust relationships to prevent confused deputy problems. The following example shows how you can use the aws:SourceArn and aws:SourceAccount global condition context keys in StackSets to prevent the confused deputy problem.

Administrator account

Example Global keys for aws:SourceAccount and aws:SourceArn

When using StackSets, define the global keys aws:SourceAccount and aws:SourceArn in your AWSCloudFormationStackSetAdministrationRole trust policy to prevent confused deputy problems.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "cloudformation.amazonaws.com"
      },
      "Action": "sts:AssumeRole",
      "Condition": {
        "StringEquals": {
          "aws:SourceAccount": "111122223333"
        },
        "StringLike": {
          "aws:SourceArn": "arn:aws:cloudformation:*:111122223333:stackset/*"
        }
      }
    }
  ]
}

Example StackSets ARNs

Specify your associated StackSets ARNs for finer control.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "cloudformation.amazonaws.com"
      },
      "Action": "sts:AssumeRole",
      "Condition": {
        "StringEquals": {
          "aws:SourceAccount": "111122223333",
          "aws:SourceArn": [
            "arn:aws:cloudformation:STACKSETS-REGION:111122223333:stackset/STACK-SET-ID-1",
            "arn:aws:cloudformation:STACKSETS-REGION:111122223333:stackset/STACK-SET-ID-2",
          ]
        }
      }
    }
  ]
}