3

tl;drOPTIONS request made from the browser to a presigned url acquired from a server (AWS S3) gets 200, but the following PUT request get 403

This is my server-side code responsible for AWS and its S3 service:

const AWS = require('aws-sdk');
const config = {
  accessKeyId: process.env.AWS_ACCESS_KEY_ID,
  secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY,
  region: process.env.AWS_BUCKET_REGION,
};
AWS.config.update(config);

const S3Bucket = new AWS.S3({
  signatureVersion: 'v4',
  params: { Bucket: process.env.AWS_BUCKET_NAME },
});

const uploadImage = async (fileData) => {
  // fileData contains `name` and `type` properties
  const Key = `images/${fileData.name}`;
  const params = {
    Bucket: process.env.AWS_BUCKET_NAME,
    Key,
    Expires: 15 * 60, // 15 minutes
    ContentType: fileData.type,
    ACL: 'public-read',
  };
  const url = await S3Bucket.getSignedUrlPromise('putObject', params);
  return url;
};

The IAM User from the code above (AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY) has the following policy attached:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "Stmt1418647210000",
            "Effect": "Allow",
            "Action": [
                "s3:Put*"
            ],
            "Resource": [
                "arn:aws:s3:::my-actual-bucket-name-here/*"
            ]
        }
    ]
}

My actual bucket has no Bucket policy set and has the following CORS configuration:

<?xml version="1.0" encoding="UTF-8"?>
<CORSConfiguration xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
<CORSRule>
    <AllowedOrigin>*</AllowedOrigin>
    <AllowedMethod>HEAD</AllowedMethod>
    <AllowedMethod>GET</AllowedMethod>
    <AllowedMethod>PUT</AllowedMethod>
    <AllowedMethod>POST</AllowedMethod>
    <MaxAgeSeconds>3000</MaxAgeSeconds>
    <AllowedHeader>*</AllowedHeader>
</CORSRule>
</CORSConfiguration>

When I make a request from the browser to my server I get a signed URL in the response. Then I use this URL to perform a put request using the following code:

// `file` is a File class object (that inherits from `FilePrototype` which inherits from `BlobPrototype` that has the following attributes
// lastModified: 1556044130023
​// name: "profile.jpg"
​​// size: 788956
​​// type: "image/jpeg"
​​// uid: "rc-upload-1578069253604-2"
​​// webkitRelativePath: ""

const url = 'https://my-actual-bucket.s3.eu-central-1.amazonaws.com/images/profile.jpg?Content-Type=image%2Fjpeg&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=MYCREDENTIALCODE%2F20200103%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20200103T163418Z&X-Amz-Expires=900&X-Amz-Signature=b90ed9cbdfadc6401521f80f5d4a65e7d4182becd392ad274ffbe3405d626055&X-Amz-SignedHeaders=host%3Bx-amz-acl&x-amz-acl=public-read';
const response = await fetch(url, {
  method: 'PUT',
  body: file,
  headers: {
    'Content-Type': file.type,
  },
});

In my Network tab I can see an OPTIONS request that ends up returning 200, and a following PUT request that ends up with 403 saying:

<Error><Code>AccessDenied</Code><Message>Access Denied</Message><RequestId>BFBCD6D538B3EB6A</RequestId><HostId>BtQuuVJw63Ixvir1ghCu0QLq/FKORNSIyyIh9AoYhul1TnsaoZZ1V0p/FBooM/0HTNhM7ZSegM8=</HostId></Error>

Any idea what am I doing wrong here?

2
  • 1
    Add s3:GetObject to your IAM policy to check if that solves the problem. Commented Jan 3, 2020 at 16:56
  • @jweyrich – it actually did! Why is this a thing? Commented Jan 3, 2020 at 17:03

1 Answer 1

4

You need to add the S3:GetObject permission to your IAM policy. This permission is required because the user (in this case the application) is ultimately granting others permission to "read" (get) an object via a pre-signed URL. Therefore, it also needs to have the "read" (get) permission.

Sign up to request clarification or add additional context in comments.

Comments

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.