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RE: [widgets] What does it mean to have an unavailable API

From: Marcin Hanclik <Marcin.Hanclik@access-company.com>
Date: Wed, 3 Jun 2009 12:16:58 +0200
To: Jonas Sicking <jonas@sicking.cc>
CC: Scott Wilson <scott.bradley.wilson@gmail.com>, Henri Sivonen <hsivonen@iki.fi>, public-webapps <public-webapps@w3.org>
Message-ID: <FAA1D89C5BAF1142A74AF116630A9F2C0A26ED909F@OBEEX01.obe.access-company.com>
Hi Jonas,

requestFeature() is mainly (still debated, though) for websites, i.e. online content where the <feature> is not present.
<feature> is for packaged widgets only.

>>However this does not seem to be true
>>if the exploited code could simply call requestFeature() first, and
>>then use the feature.
Calling requestFeature() does not mean that the security aspects are omitted.
The check against the security policy happens when requestFeature() is called.


Kind regards,

Marcin Hanclik
ACCESS Systems Germany GmbH
Tel: +49-208-8290-6452  |  Fax: +49-208-8290-6465
Mobile: +49-163-8290-646
E-Mail: marcin.hanclik@access-company.com
-----Original Message-----
From: Jonas Sicking [mailto:jonas@sicking.cc]
Sent: Tuesday, June 02, 2009 7:19 PM
To: Marcin Hanclik
Cc: Scott Wilson; Henri Sivonen; public-webapps
Subject: Re: [widgets] What does it mean to have an unavailable API

On Tue, Jun 2, 2009 at 7:28 AM, Marcin Hanclik
<Marcin.Hanclik@access-company.com> wrote:
> Hi Scott,
> In BONDI we have discussed the (has/request)Feature() for some time.
> http://bondi.omtp.org/1.0/security/BONDI_Architecture_and_Security_v1.0.pdf, section 4.3
> A few points for further discussion:
> 1. feature (at least in BONDI) is an abstract thing, not just one function. So hasFeature() is simply optimized checking procedure. If you check for a feature and discover that it is available, you may/should/must assume that a set of functions is available. Otherwise, you have to check each function individually and basically you cannot assume that if one functions is available, then the other is as well.
> 2. requestFeature() adds dynamism to the Website content. Widgets express their dependency statically by <feature>.
> http://bondi.omtp.org/1.0/security/BONDI_Architecture_and_Security_Appendices_v1.0.pdf B.2 specifies more details.

Doesn't the requestFeature() make at least the security benefits of
<feature> moot? In Another thread Marcos stated that one of the
benefits of <feature> was that if a widget gets exploited, the
exploited code couldn't get access to any features that the widget
hadn't enabled using <feature>. However this does not seem to be true
if the exploited code could simply call requestFeature() first, and
then use the feature.

/ Jonas


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Received on Wednesday, 3 June 2009 10:17:53 UTC

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