How to fix AccessDenied calling CopyObject

Question

I'm trying to copy files from a bucket in A account to another bucket but in B account. When I try to sync the files with the command

aws s3 sync s3://BUCKET_A s3://BUCKET_B

It returns the following output:

copy failed: s3://BUCKET_A to s3://BUCKET_B An error occurred (AccessDenied) when calling the CopyObject operation: Access Denied

This is the policy that was attached to user created in in B account (where will be copied files from bucket A):

{
    "Version": "2012-10-17",
    "Statement": [
      {
          "Effect": "Allow",
          "Action": [
              "s3:ListBucket",
              "s3:GetObject",
              "s3:PutObject",
              "s3:PutObjectAcl"
          ],
          "Resource": [
              "arn:aws:s3:::BUCKET_A",
              "arn:aws:s3::: BUCKET_A/*"
          ]
      },
      {
          "Effect": "Allow",
          "Action": [
              "s3:ListBucket",
              "s3:GetObject",
              "s3:PutObject",
              "s3:PutObjectAcl"
          ],
          "Resource": [
              "arn:aws:s3:::BUCKET_B",
              "arn:aws:s3:::BUCKET_B/*"
          ]
      }
    ]
}

Probably I missing some permission? I don't find the permission CopyObject to add in my user/bucket policy

Answer 1

On your IAM Role Policy side you will need the following:

  {
    "Version": "2012-10-17",
    "Statement": [
      {
          "Effect": "Allow",
          "Action": [
              "s3:ListBucket",
              "s3:GetObject",
              "s3:PutObject",
              "s3:PutObjectAcl"
          ],
          "Resource": [
              "arn:aws:s3:::BUCKET_A",
              "arn:aws:s3::: BUCKET_A/*"
          ]
      },
      {
          "Effect": "Allow",
          "Action": [
              "s3:ListBucket",
              "s3:GetObject",
              "s3:PutObject",
              "s3:PutObjectAcl"
          ],
          "Resource": [
              "arn:aws:s3:::BUCKET_B",
              "arn:aws:s3:::BUCKET_B/*"
          ]
      }
    ]
}

You need to add these permissions to BUCKET_B

{
         "Sid": "Example permissions",
         "Effect": "Allow",
         "Principal": {
            "AWS": "arn:aws:iam::your_iam_policy"
         },
         "Action": [
              "s3:ListBucket",
              "s3:GetObject",
              "s3:PutObject",
              "s3:PutObjectAcl"
          ],
         ],
         "Resource": [
            "arn:aws:s3:::BUCKET_B"
         ]
      }