Restrict access to bucket prefixes

It is possible to use custom roles and policies in the Quilt Catalog to limit access to specific folders in an S3 bucket. Nevertheless, this approach has limitations and is therefore not recommended for high-security data where not just the contents but the names of files and folders are sensitive.


  • IAM policies and roles (see below for an example)

  • Quilt Catalog Admin status

  • For cross-account roles, you must have a recent version of the Quilt Stack (1-Feb-2023 or later) so that the Quilt registry has sufficient permissions to assume cross-account roles on behalf of users

  • Ask your Quilt Account Manager to enable "prefix-aware search" for your stack in order for search to hide the objects from unauthorized users in the search results.

Limitations and workarounds

  • Roles for users of the Quilt Catalog's Bucket tab must have full ListBucket permissions, whether or not they are allowed to access all folders and objects. Catalog users who click on a prefix or object that they are not permitted to access will see an Access Denied message.

    IAM is not designed as a filter for browsing S3. ListBucket will return a 403 error for the root of bucket if users do not have full permissions (currently incompatible with the Quilt Catalog)

  • Similar to prefixes (above), Quilt Packages that reference prefixes that users cannot access via IAM will reveal package-relative file names and object-level Quilt metadata, but will neither reveal S3 object metadata nor S3 object contents. Clicking on a package entry in the Catalog that has a physical key that the user is not allowed to access will display an Access Denied message.

  • Prefix-aware search performs a head request on every object result; this may slow search performance in the Catalog

Requirements and recommendations

  • Manage all Quilt roles and policies for prefixes with the Quilt Catalog Admin Panel

  • Provided that you use roles created in the Quilt Catalog Admin Panel you do not need to, and should not, insert a trust relationship into your roles by hand.

In certain rare circumstances (e.g. upgrading from an older Quilt stack for cross-account role assumption) if Quilt is not working as expected you can rename, remove, or add a Quilt managed role in order to force the Quilt stack to update its permissions state.


You can attach a "custom" policy to a role with the Quilt Catalog Admin Panel similar to the following:

    "Version": "2012-10-17",
    "Statement": [
            "Effect": "Allow",
            "Action": [
            "Resource": [

The .quilt folder is where Quilt Package Manifests are stored for all packages in a bucket registry. Users must have access to this directory to view Packages.

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