How do I have an S3 bucket return 404 (instead of

问题:

I am using S3 to store some business critical documents. I want the bucket to return a 404 status code when trying to access an object that does not exist in the bucket.

However, I am finding that it keeps on returning me "403

here is an example of a session using the S3 website url.

> GET /foobar.txt HTTP/1.1
> User-Agent: curl/7.21.6 (x86_64-pc-linux-gnu) libcurl/7.21.6 OpenSSL/1.0.0e zlib/1.2.3.4 libidn/1.22 librtmp/2.3
> Host: <bucketname>.s3-website-us-east-1.amazonaws.com
> Accept: */*
> 
< HTTP/1.1 403 Forbidden
< Last-Modified: Mon, 09 Sep 2013 19:10:28 GMT
< ETag: "14e13b81b3ce5b129d1f206b3e514885"
< x-amz-error-code: AccessDenied
< x-amz-error-message: Access Denied
< x-amz-request-id: <snip>
< x-amz-id-2: <snip>
< Content-Type: text/html
< Content-Length: 11
< Date: Thu, 26 Sep 2013 20:01:45 GMT
< Server: AmazonS3
< 
Not found!

Note, the "Not Found!" string is coming from the error document set on the bucket properties when enabling S3 website hosting.

I have also tried accessing using the bucket url directly

http://.s3.amazonaws.com/

and that returns the same, except that instead of the error document, I get a XML document

How do I solve this problem?

回答1:

S3 returns a 403 instead of a 404 when the user doesn't have permission to list the bucket contents.

If you query for an object and receive a 404, then you know that object doesn't exist. This is information you shouldn't know if you don't have permission to list the bucket contents so instead of telling you it doesn't exist, S3 just tells you that you're trying to do something you're not allowed to do. When you get a 403 instead of a 404 you have no way of knowing that the object you requested doesn't exist. It might not exist or it might exist and you just don't have permission to access it. There's no way for you to know for sure and so no security is bypassed.

I believe anyone with access to list the bucket contents will get a 404 instead of a 403.

回答2:

The exact requirement seems to be that your user has ListBucket permission for your particular bucket AND the ARN is exactly of the form arn:aws:s3:::your_bucket_name.

I also needed to add a completely new statement to my policy because other permissions like GetObject still require that the ARN ends with /* or some other suitable wildcard.

{
  "Action": [
    "s3:ListBucket"
  ],
  "Sid": "StmtNNNNNNNNNNNNNNNwholebucket",
  "Resource": [
    "arn:aws:s3:::your_bucket_name"
  ],
  "Effect": "Allow"
},

To summarize, the important bit for me was that if the ARN is NOT of the form arn:aws:s3:::your_bucket_name/* for ListBucket or you will still get 403 instead of 404.

回答3:

Make sure in your permissions Everyone has View Permissions.

You may want to add a bucket policy too:

{
    "Version": "2008-10-17",
    "Statement": [
        {
            "Sid": "PublicReadGetObject",
            "Effect": "Allow",
            "Principal": {
                "AWS": "*"
            },
            "Action": "s3:GetObject",
            "Resource": "arn:aws:s3:::your_bucket_name/*"
        }
    ]
}