Ensure permissions are tightly controlled for AWS EFS File System

EFS with sensitive permissions may lead to unauthorized access and/or data leak.

In AWS Console -

1. Sign in to the AWS Console and go to the Amazon EFS console.
2. Select File Systems.
3. Click the file system that you want to configure. Select Permissions.
4. In the File system policy, select the policy statement.
5. Click Edit and make the necessary changes.

In Terraform -

1. In the aws_efs_file_system_policy resource, configure the policy field accordingly.

References:
https://docs.aws.amazon.com/efs/latest/ug/auth-and-access-control.html
https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/efs_file_system_policy