policy.json

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "Stmt1444712245000",
            "Effect": "Allow",
            "Action": [
                "ec2:ModifyImageAttribute"
            ],
            "Condition": {
                "Bool": {
                    "ec2:ResourceTag/CustomerShareable": "true"
                }
            },
            "Resource": [
                "*"
            ]
        }
    ]
}