Basic AWS IAM permissions for an S3 bucket

Question

I'm trying to figure out a basic permission set for an IAM user/key to have to have access to only a single bucket in S3 - only read/write access on an individual bucket.

What set of permissions is the minimum required to make this work? I have all options selected in the IAM policy generator for S3, all permissions enabled on the bucket except CreateBucket and DeleteBucket . I've also created a set of keys specific to this user.

When I try to access the bucket with these credentials, I get a problem listing buckets, even though the ListAllMyBuckets property is enabled.

Anyone have any experience setting up a basic bucket config like this? Seems like it would be pretty common...

Answer 1

The Example Policies for Amazon S3 cover various use cases similar or related to yours - specifically you might probably want to combine Example 1: Allow each user to have a home directory in Amazon S3 with Example 2: Allow a user to list only the objects in his or her home directory in the corporate bucket - you'd just need to adjust the Resource to target your buckets root directory instead, ie replace /home/bob/* with * .

Please note that Example 2 facilitates ListBucket , which is an operation on a bucket that returns information about some of the items in the bucket , whereas ListAllMyBuckets is an operation on the service that returns a list of all buckets owned by the sender of the request , so likely not applicable to your use case (see my comment regarding clarification of the latter).

Answer 2

This will permit to list all buckets assuming you are not denying it somewhere else (I am 99% sure deny statements are evaluated first; order does not matter with IAM policies):

    {
        "Effect": "Allow",
        "Action": [
            "s3:ListAllMyBuckets"
        ],
        "Resource": "*"
    }

Permit whatever you want for your buckets (Don't forget the /* also):

    {
        "Effect": "Allow",
        "Action": [
            "s3:<Put your actions here; cherry pick from the AWS documentation>"
        ],
        "Resource": [
            "arn:aws:s3:::<Bucket name here>",
            "arn:aws:s3:::<Bucket name here>/*"
        ]
    }