AWS S3 ListMultipartUploads：访问被拒绝

Question

I have followed this blog in order to setup my AWS IAM and S3 accounts with Web Identity Federation. I am able to authenticate and receive session credentials and tokens all fine. I am also able to Download and Upload objects. However, I am getting:

access denied

on the following ListMultipartUploads request:

var request = new ListMultipartUploadsRequest()
{
    BucketName = bucketName,
    Prefix = $"{UserId}/"
};

var response = await s3Client.ListMultipartUploadsAsync(request);

The access policy attached to my IAM role is:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "s3:AbortMultipartUpload",
                "s3:DeleteObject",
                "s3:GetObject",
                "s3:PutObject"
            ],
            "Resource": "arn:aws:s3:::mybucket/${myidentityprovider:userId}/*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "s3:ListBucket",
                "s3:ListBucketMultipartUploads"
            ],
            "Resource": [
                "arn:aws:s3:::mybucket"
            ],
            "Condition": {
                "StringLike": {
                    "s3:prefix": "${myidentityprovider:userId}/"
                }
            }
        }
    ]
}

As you can see, I have the permission "s3:ListBucketMultipartUploads", so the user should be able to perform ListMultiPartUploads on their buckets. What am I doing wrong?

Answer 1

I see an error in your prefix statement,

It needs to be an array,

"s3:prefix": ["${myidentityprovider:userId}/*"]

{
"Version": "2012-10-17",
"Statement": [
    {
        "Effect": "Allow",
        "Action": [
            "s3:AbortMultipartUpload",
            "s3:DeleteObject",
            "s3:GetObject",
            "s3:PutObject"
        ],
        "Resource": "arn:aws:s3:::mybucket/${myidentityprovider:userId}/*"
    },
    {
        "Effect": "Allow",
        "Action": [
            "s3:ListBucket",
            "s3:ListBucketMultipartUploads"
        ],
        "Resource": [
            "arn:aws:s3:::mybucket"
        ],
        "Condition": {
            "StringLike": {
                "s3:prefix": ["${myidentityprovider:userId}/*"]
            }
        }
    }
]}