Access point policy examples Condition keys Delegating access control to access points Granting permissions for cross-account access points

Configuring IAM policies for using access points

Amazon S3 access points support AWS Identity and Access Management (IAM) resource policies that allow you to control the use of the access point by resource, user, or other conditions. For an application or user to be able to access objects through an access point, both the access point and the underlying bucket must permit the request.

Important

Adding an S3 access point to a bucket doesn't change the bucket's behavior when the bucket is accessed directly through the bucket's name or Amazon Resource Name (ARN). All existing operations against the bucket will continue to work as before. Restrictions that you include in an access point policy apply only to requests made through that access point.

When you're using IAM resource policies, make sure to resolve security warnings, errors, general warnings, and suggestions from AWS Identity and Access Management Access Analyzer before you save your policy. IAM Access Analyzer runs policy checks to validate your policy against IAM policy grammar and best practices. These checks generate findings and provide recommendations to help you author policies that are functional and conform to security best practices.

To learn more about validating policies by using IAM Access Analyzer, see IAM Access Analyzer policy validation in the IAM User Guide. To view a list of the warnings, errors, and suggestions that are returned by IAM Access Analyzer, see IAM Access Analyzer policy check reference.

Access point policy examples

The following examples demonstrate how to create IAM policies to control requests made through an access point.

Note

Permissions granted in an access point policy are effective only if the underlying bucket also allows the same access. You can accomplish this in two ways:

(Recommended) Delegate access control from the bucket to the access point, as described in Delegating access control to access points.
Add the same permissions contained in the access point policy to the underlying bucket's policy. The Example 1 access point policy example demonstrates how to modify the underlying bucket policy to allow the necessary access.

Example 1 – Access point policy grant

The following access point policy grants IAM user Jane in account 123456789012 permissions to GET and PUT objects with the prefix Jane/ through the access point my-access-point in account 123456789012.


{
    "Version":"2012-10-17",
    "Statement": [
    {
        "Effect": "Allow",
        "Principal": {
            "AWS": "arn:aws:iam::123456789012:user/Jane"
        },
        "Action": ["s3:GetObject", "s3:PutObject"],
        "Resource": "arn:aws:s3:us-west-2:123456789012:accesspoint/my-access-point/object/Jane/*"
    }]
}

Note

For the access point policy to effectively grant access to Jane, the underlying bucket must also allow the same access to Jane. You can delegate access control from the bucket to the access point as described in Delegating access control to access points. Or, you can add the following policy to the underlying bucket to grant the necessary permissions to Jane. Note that the Resource entry differs between the access point and bucket policies.


{
    "Version": "2012-10-17",
    "Statement": [
    {
        "Effect": "Allow",
        "Principal": {
            "AWS": "arn:aws:iam::123456789012:user/Jane"
        },
        "Action": ["s3:GetObject", "s3:PutObject"],
        "Resource": "arn:aws:s3:::amzn-s3-demo-bucket1/Jane/*"
    }]    
}

Example 2 – Access point policy with tag condition

The following access point policy grants IAM user Mateo in account 123456789012 permissions to GET objects through the access point my-access-point in the account 123456789012 that have the tag key data set with a value of finance.


{
    "Version":"2012-10-17",
    "Statement": [
    {
        "Effect":"Allow",
        "Principal" : {
            "AWS": "arn:aws:iam::123456789012:user/Mateo"
        },
        "Action":"s3:GetObject",
        "Resource" : "arn:aws:s3:us-west-2:123456789012:accesspoint/my-access-point/object/*",
        "Condition" : {
            "StringEquals": {
                "s3:ExistingObjectTag/data": "finance"
            }
        }
    }]
}

Example 3 – Access point policy that allows bucket listing

The following access point policy allows IAM user Arnav in the account 123456789012 permission to view the objects contained in the bucket underlying the access point my-access-point in the account 123456789012.


{
    "Version":"2012-10-17",
    "Statement": [
    {
        "Effect": "Allow",
        "Principal": {
            "AWS": "arn:aws:iam::123456789012:user/Arnav"
        },
        "Action": "s3:ListBucket",
        "Resource": "arn:aws:s3:us-west-2:123456789012:accesspoint/my-access-point"
    }]
}

Example 4 – Service control policy

The following service control policy requires all new access points to be created with a virtual private cloud (VPC) network origin. With this policy in place, users in your organization can't create new access points that are accessible from the internet.


{
    "Version": "2012-10-17",
    "Statement": [
    {
        "Effect": "Deny",
        "Action": "s3:CreateAccessPoint",
        "Resource": "*",
        "Condition": {
            "StringNotEquals": {
                "s3:AccessPointNetworkOrigin": "VPC"
            }
        }
    }]
}

Example 5 – Bucket policy to limit S3 operations to VPC network origins

The following bucket policy limits access to all S3 object operations for the bucket amzn-s3-demo-bucket to access points with a VPC network origin.

Important

Before using a statement like the one shown in this example, make sure that you don't need to use features that aren't supported by access points, such as Cross-Region Replication.


{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Deny",
            "Principal": "*",
            "Action": [
                "s3:AbortMultipartUpload",
                "s3:BypassGovernanceRetention",
                "s3:DeleteObject",
                "s3:DeleteObjectTagging",
                "s3:DeleteObjectVersion",
                "s3:DeleteObjectVersionTagging",
                "s3:GetObject",
                "s3:GetObjectAcl",
                "s3:GetObjectLegalHold",
                "s3:GetObjectRetention",
                "s3:GetObjectTagging",
                "s3:GetObjectVersion",
                "s3:GetObjectVersionAcl",
                "s3:GetObjectVersionTagging",
                "s3:ListMultipartUploadParts",
                "s3:PutObject",
                "s3:PutObjectAcl",
                "s3:PutObjectLegalHold",
                "s3:PutObjectRetention",
                "s3:PutObjectTagging",
                "s3:PutObjectVersionAcl",
                "s3:PutObjectVersionTagging",
                "s3:RestoreObject"
            ],
            "Resource": "arn:aws:s3:::amzn-s3-demo-bucket/*",
            "Condition": {
                "StringNotEquals": {
                    "s3:AccessPointNetworkOrigin": "VPC"
                }
            }
        }
    ]
}

Condition keys

S3 access points have condition keys that you can use in IAM policies to control access to your resources. The following condition keys represent only part of an IAM policy. For full policy examples, see Access point policy examples, Delegating access control to access points, and Granting permissions for cross-account access points.

s3:DataAccessPointArn

This example shows a string that you can use to match on an access point ARN. The following example matches all access points for AWS account 123456789012 in Region us-west-2:


"Condition" : {
    "StringLike": {
        "s3:DataAccessPointArn": "arn:aws:s3:us-west-2:123456789012:accesspoint/*"
    }
}

s3:DataAccessPointAccount

This example shows a string operator that you can use to match on the account ID of the owner of an access point. The following example matches all access points that are owned by the AWS account 123456789012.


"Condition" : {
    "StringEquals": {
        "s3:DataAccessPointAccount": "123456789012"
    }
}

s3:AccessPointNetworkOrigin

This example shows a string operator that you can use to match on the network origin, either Internet or VPC. The following example matches only access points with a VPC origin.


"Condition" : {
    "StringEquals": {
        "s3:AccessPointNetworkOrigin": "VPC"
    }
}

For more information about using condition keys with Amazon S3, see Actions, resources, and condition keys for Amazon S3 in the Service Authorization Reference.

For more information about the permissions to S3 API operations by S3 resource types, see Required permissions for Amazon S3 API operations.

Delegating access control to access points

You can delegate access control for a bucket to the bucket's access points. The following example bucket policy allows full access to all access points that are owned by the bucket owner's account. Thus, all access to this bucket is controlled by the policies attached to its access points. We recommend configuring your buckets this way for all use cases that don't require direct access to the bucket.

Example 6 – Bucket policy that delegates access control to access points


{
    "Version": "2012-10-17",
    "Statement" : [
    {
        "Effect": "Allow",
        "Principal" : { "AWS": "*" },
        "Action" : "*",
        "Resource" : [ "Bucket ARN", "Bucket ARN/*"],
        "Condition": {
            "StringEquals" : { "s3:DataAccessPointAccount" : "Bucket owner's account ID" }
        }
    }]
}

Granting permissions for cross-account access points

To create an access point to a bucket that's owned by another account, you must first create the access point by specifying the bucket name and account owner ID. Then, the bucket owner must update the bucket policy to authorize requests from the access point. Creating an access point is similar to creating a DNS CNAME in that the access point doesn't provide access to the bucket contents. All bucket access is controlled by the bucket policy. The following example bucket policy allows GET and LIST requests on the bucket from an access point that's owned by a trusted AWS account.

Replace Bucket ARN with the ARN of the bucket.

Example 7 – Bucket policy delegating permissions to another AWS account


{
    "Version": "2012-10-17",
    "Statement" : [
    {
        "Effect": "Allow",
        "Principal" : { "AWS": "*" },
        "Action" : ["s3:GetObject","s3:ListBucket"],
        "Resource" : [ "Bucket ARN", "Bucket ARN/*"],
        "Condition": {
            "StringEquals" : { "s3:DataAccessPointAccount" : "Access point owner's account ID" }
        }
    }]
}

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Creating access points