# Cross-domain Policy File

A cross-domain policy file allows web pages hosted elsewhere to use client side technologies such as Flash, Java and Silverlight to interact with the Swift API.

See https://www.adobe.com/devnet-docs/acrobatetk/tools/AppSec/xdomain.html for a description of the purpose and structure of the cross-domain policy file. The cross-domain policy file is installed in the root of a web server (i.e., the path is `/crossdomain.xml`).

The crossdomain middleware responds to a path of `/crossdomain.xml` with an XML document such as:

    <?xml version="1.0"?>
    <!DOCTYPE cross-domain-policy SYSTEM "http://www.adobe.com/xml/dtds/cross-domain-policy.dtd" >
    <cross-domain-policy>
        <allow-access-from domain="*" secure="false" />
    </cross-domain-policy>

You should use a policy appropriate to your site. The examples and the default policy are provided to indicate how to syntactically construct a cross domain policy file – they are not recommendations.

## Configuration

To enable this middleware, add it to the pipeline in your proxy-server.conf file. It should be added before any authentication (e.g., tempauth or keystone) middleware. In this example ellipsis (…) indicate other middleware you may have chosen to use:

    [pipeline:main]
    pipeline =  ... crossdomain ... authtoken ... proxy-server

And add a filter section, such as:

    [filter:crossdomain]
    use = egg:swift#crossdomain
    cross_domain_policy = <allow-access-from domain="*.example.com" />
        <allow-access-from domain="www.example.com" secure="false" />

For continuation lines, put some whitespace before the continuation text. Ensure you put a completely blank line to terminate the `cross_domain_policy` value.

The `cross_domain_policy` name/value is optional. If omitted, the policy defaults as if you had specified:

    cross_domain_policy = <allow-access-from domain="*" secure="false" />

Note

The default policy is very permissive; this is appropriate for most public cloud deployments, but may not be appropriate for all deployments. See also: CWE-942

this page last updated: 2026-04-08 16:47:21

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