How AWS Transfer Family works with IAM - AWS Transfer Family

How AWS Transfer Family works with IAM

Before you use AWS Identity and Access Management (IAM) to manage access to AWS Transfer Family, you should understand what IAM features are available to use with AWS Transfer Family. To get a high-level view of how AWS Transfer Family and other AWS services work with IAM, see AWS services that work with IAM in the IAM User Guide.

AWS Transfer Family identity-based policies

With IAM identity-based policies, you can specify allowed or denied actions and resources as well as the conditions under which actions are allowed or denied. AWS Transfer Family supports specific actions, resources, and condition keys. To learn about all of the elements that you use in a JSON policy, see IAM JSON policy elements reference in the AWS Identity and Access Management User Guide.

Actions

The Action element of an IAM identity-based policy describes the specific action or actions that will be allowed or denied by the policy. Policy actions usually have the same name as the associated AWS API operation. The action is used in a policy to grant permissions to perform the associated operation.

Policy actions in AWS Transfer Family use the following prefix before the action: AWS Transfer Family:. For example, to grant someone permission to run an Amazon EC2 instance with the Amazon EC2 RunInstances API operation, you include the ec2:RunInstances action in their policy. Policy statements must include either an Action or NotAction element. AWS Transfer Family defines its own set of actions that describe tasks that you can perform with this service.

To specify multiple actions in a single statement, separate them with commas as follows.

"Action": [ "ec2:action1", "ec2:action2"

You can specify multiple actions using wildcards (*). For example, to specify all actions that begin with the word Describe, include the following action.

"Action": "ec2:Describe*"

To see a list of AWS Transfer Family actions, see Actions Defined by AWS Transfer Family in the IAM User Guide.

Resources

The Resource element specifies the object or objects to which the action applies. Statements must include either a Resource or a NotResource element. You specify a resource using an ARN or using the wildcard (*) to indicate that the statement applies to all resources.

The Amazon EC2 instance resource has the following ARN.

arn:${Partition}:ec2:${Region}:${Account}:instance/${InstanceId}

For more information about the format of ARNs, see Amazon Resource Names (ARNs) and AWS service namespaces.

For example, to specify the i-1234567890abcdef0 instance in your statement, use the following ARN.

"Resource": "arn:aws:ec2:us-east-1:123456789012:instance/i-1234567890abcdef0"

To specify all instances that belong to a specific account, use the wildcard (*).

"Resource": "arn:aws:ec2:us-east-1:123456789012:instance/*"

Some AWS Transfer Family actions, such as those for creating resources, cannot be performed on a specific resource. In those cases, you must use the wildcard (*).

"Resource": "*"

Many Amazon EC2 API actions involve multiple resources. For example, AttachVolume attaches an Amazon EBS volume to an instance, so an IAM user must have permissions to use the volume and the instance. To specify multiple resources in a single statement, separate the ARNs with commas.

"Resource": [ "resource1", "resource2"

To see a list of AWS Transfer Family resource types and their ARNs, see Resources Defined by AWS Transfer Family in the AWS Identity and Access Management User Guide. To learn with which actions you can specify the ARN of each resource, see Actions Defined by AWS Transfer Family.

Condition keys

The Condition element (or Condition block) lets you specify conditions in which a statement is in effect. The Condition element is optional. You can build conditional expressions that use condition operators, such as equals or less than, to match the condition in the policy with values in the request.

If you specify multiple Condition elements in a statement, or multiple keys in a single Condition element, AWS evaluates them using a logical AND operation. If you specify multiple values for a single condition key, AWS evaluates the condition using a logical OR operation. All of the conditions must be met before the statement's permissions are granted.

You can also use placeholder variables when you specify conditions. For example, you can grant an IAM user permission to access a resource only if it is tagged with their IAM user name. For more information, see IAM Policy Elements: Variables and Tags in the IAM User Guide.

AWS Transfer Family defines its own set of condition keys and also supports using some global condition keys. To see all AWS global condition keys, see AWS Global condition context keys in the AWS Identity and Access Management User Guide.

All Amazon EC2 actions support the aws:RequestedRegion and ec2:Region condition keys. For more information, see Example: restricting access to a specific region.

To see a list of AWS Transfer Family condition keys, see Condition Keys for AWS Transfer Family in the AWS Identity and Access Management User Guide. To learn with which actions and resources you can use a condition key, see Actions Defined by AWS Transfer Family.

Examples

To view examples of AWS Transfer Family identity-based policies, see AWS Transfer Family identity-based policy examples.

AWS Transfer Family resource-based policies

Resource-based policies are JSON policy documents that specify what actions a specified principal can perform on the AWS Transfer Family resource and under what conditions. Amazon S3 supports resource-based permissions policies for Amazon S3 buckets. Resource-based policies let you grant usage permission to other accounts on a per-resource basis. You can also use a resource-based policy to allow an AWS service to access your Amazon S3 buckets.

To enable cross-account access, you can specify an entire account or IAM entities in another account as the principal in a resource-based policy. Adding a cross-account principal to a resource-based policy is only half of establishing the trust relationship. When the principal and the resource are in different AWS accounts, you must also grant the principal entity permission to access the resource. Grant permission by attaching an identity-based policy to the entity. However, if a resource-based policy grants access to a principal in the same account, no additional identity-based policy is required. For more information, see How IAM roles differ from resource-based policies in the AWS Identity and Access Management User Guide.

The Amazon S3 service supports only one type of resource-based policy called a bucket policy, which is attached to a bucket. This policy defines which principal entities (accounts, users, roles, and federated users) can perform actions on the widget.

To learn how to attach a resource-based policy to a bucket, see >Create an IAM role and policy.

Examples

To view examples of AWS Transfer Family resource-based policies, see AWS Transfer Family resource-based policy examples.

Authorization based on AWS Transfer Family tags

You can attach tags to AWS Transfer Family resources or pass tags in a request to AWS Transfer Family. To control access based on tags, you provide tag information in the condition element of a policy using the AWS Transfer Family:ResourceTag/key-name, aws:RequestTag/key-name, or aws:TagKeys condition keys. For information about how to use tags to control access to AWS Transfer Family resources, see AWS Transfer Family resource-based policy examples.

To view an example identity-based policy for limiting access to a resource based on the tags on that resource, see Viewing AWS Transfer Family widgets based on tags.

AWS Transfer Family IAM roles

An IAM role is an entity within your AWS account that has specific permissions.

Using temporary credentials with AWS Transfer Family

You can use temporary credentials to sign in with federation, assume an IAM role, or to assume a cross-account role. You obtain temporary security credentials by calling AWS STS API operations such as AssumeRole or GetFederationToken.

AWS Transfer Family supports using temporary credentials.