Grant Access to a Single S3 Bucket via Amazon IAM

Create an IAM user to only allow access to specific resources.

Go to Users > Attach User Policy > Policy Generator on the web console.

ref:
https://console.aws.amazon.com/iam/home?#users

Allow Full Access to Certain Buckets

Full access to single bucket:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "s3:*",
      "Resource": [
        "arn:aws:s3:::files.albedo.one",
        "arn:aws:s3:::files.albedo.one/*"
      ]
    }
  ]
}

For BackWPup, a WordPress plugin:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "VisualEditor0",
      "Effect": "Allow",
      "Action": ["s3:ListBucket"],
      "Resource": "arn:aws:s3:::*"
    },
    {
      "Sid": "VisualEditor1",
      "Effect": "Allow",
      "Action": ["s3:CreateBucket", "s3:DeleteObject"],
      "Resource": [
        "arn:aws:s3:::files.vinta.ws",
        "arn:aws:s3:::files.vinta.ws/*",
        "arn:aws:s3:::vinta-ws-backup",
        "arn:aws:s3:::vinta-ws-backup/*"
      ]
    },
    {
      "Sid": "VisualEditor2",
      "Effect": "Allow",
      "Action": ["s3:Get*", "s3:List*", "s3:Put*"],
      "Resource": [
        "arn:aws:s3:::files.vinta.ws",
        "arn:aws:s3:::files.vinta.ws/*",
        "arn:aws:s3:::vinta-ws-backup",
        "arn:aws:s3:::vinta-ws-backup/*"
      ]
    }
  ]
}

Only Allow Get/Put Objects

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": ["s3:ListBucket", "s3:ListAllMyBuckets"],
      "Resource": "arn:aws:s3:::*"
    },
    {
      "Effect": "Allow",
      "Action": ["s3:GetObject", "s3:PutObject"],
      "Resource": ["arn:aws:s3:::metadata.vinta.ws*"]
    }
  ]
}

S3 Storage Lens

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "VisualEditor0",
      "Effect": "Allow",
      "Action": [
        "s3:GetStorageLensConfiguration",
        "s3:GetStorageLensDashboard"
      ],
      "Resource": "arn:aws:s3:*:*:storage-lens/*"
    },
    {
      "Sid": "VisualEditor1",
      "Effect": "Allow",
      "Action": "s3:ListStorageLensConfigurations",
      "Resource": "*"
    }
  ]
}