What is the role of the iam:PassRole permission in AWS?

The iam:PassRole permission is critical in AWS because it grants users the ability to delegate an IAM role to an AWS service, allowing that service to perform actions on behalf of the user. When a user has this permission, they can specify which IAM role the service should use, enabling the service to take on the permissions defined in that role while executing tasks.

For instance, when launching an EC2 instance with an associated IAM role, the user must have the iam:PassRole permission to attach that role to the instance. This capability is essential for maintaining security since it ensures that only authorized users can delegate roles that might have specific permissions to access AWS resources.

This permission does not allow for assuming roles, creating new roles or deleting existing roles, but rather focuses on the delegation aspect. The correct understanding of this permission is vital for managing access and secure role assignment within AWS environments.