W3C home > Mailing lists > Public > public-webappsec@w3.org > May 2013

Re: [filter-effects][css-masking] Move security model for resources to CSP

From: Robert O'Callahan <robert@ocallahan.org>
Date: Fri, 31 May 2013 01:34:22 +1200
Message-ID: <CAOp6jLb31-WCDkmqYL97uAvFmvf7QUZXpu4_-CZuHsp8ZCfQEA@mail.gmail.com>
To: Anne van Kesteren <annevk@annevk.nl>
Cc: Dirk Schulze <dschulze@adobe.com>, Bjoern Hoehrmann <derhoermi@gmx.net>, "public-fx@w3.org" <public-fx@w3.org>, "public-webappsec@w3.org" <public-webappsec@w3.org>, Daniel Holbert <dholbert@mozilla.com>, Philip Rogers <pdr@google.com>
On Fri, May 31, 2013 at 1:10 AM, Anne van Kesteren <annevk@annevk.nl> wrote:

> On Thu, May 30, 2013 at 12:35 AM, Robert O'Callahan
> <robert@ocallahan.org> wrote:
> > Note that if we do this, we'll need to continue to apply an origin check
> > when filter/mask/clip/use/pattern etc refer to an element in an external
> > document, at the time they use the element. Anne, can we make regular
> image
> > loads record presence of an Access-Control-Allow-Origin header if the
> server
> > sends one, without causing the load to fail if it happens to be
> cross-origin
> > with no header?
> There's no such concept right now. You either opt into CORS or you get
> a tainted cross-origin request which cannot be untainted. Note this
> would also be problematic with respect to cookies, unless you'll do
> something different for those than tainted cross-origin requests do.

OK then, I think we'd have to use a regular non-CORS request and apply
strict same-origin checking at time of use.

We could however mint a "cors-url(...)" CSS image value which does a CORS
fetch and completely fails for cross-origin loads.

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Received on Thursday, 30 May 2013 13:35:01 UTC

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