Adding a condition to an IAM Permission causes ec2:CreateImage to not be authorized

Question

So I have a SSO Role, and I added ec2:CreateImage to the permission set attached to it, and resource is "*". It works fine. As soon as I add a condition like "StringEquals", with the condition being a tag, i.e. aws:ResourceTag/Example, it will not work. It does not have some explicit deny etc. The tag value is correct. I've tried different key,values to rule out spelling errors or some silly mistake.

I have tested this in two different environments and I trouble shooted using the Policy Builder (So no syntax issues). I have double checked by deleting the permission (and seeing it blocked), adding the bare permission without conditions (it passes), and then adding a condition (it then fails).

I dont see anything in the documentation or dependencies that would cause this to fail. Any reason?

Answer

Reading your question, it sounds like you are trying to specify `Resource:*` when using the ConditionKey `aws:ResourceTag/${TagKey}`. For the action `ec2:CreateImage`, you must also specify which Resource type when using this ConditionKey. In this case, the Resource type is `instance` as the other supported Resource type `image` does not support this ConditionKey.

https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazonec2.html#amazonec2-policy-keys

> If the column includes a resource type, then you can specify an ARN of that type in a statement with that action. Required resources are indicated in the table with an asterisk (*). If you specify a resource-level permission ARN in a statement using this action, then it must be of this type. Some actions support multiple resource types. If the resource type is optional (not indicated as required), then you can choose to use one but not the other.

For example, to match tags on all ec2 instances in an account with ID 111111111111, we must specify `"Resource": "arn:aws:ec2:*: 111111111111:instance/*"`

```{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "VisualEditor0",
            "Effect": "Allow",
            "Action": "ec2:CreateImage",
            "Resource": "arn:aws:ec2:*:111111111111:instance/*",
            "Condition": {
                "StringEquals": {
                    "aws:ResourceTag/TAG_KEY": "TAG_VALUE"
                }
            }
        }
    ]
}```

Adding a condition to an IAM Permission causes ec2:CreateImage to not be authorized

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