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Re: [css-color][filter-effects] (was: Re: [filter-effects] Tainted filter primitives)

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Fri, 3 Jan 2014 13:55:43 -0800
Message-ID: <CAAWBYDC1hKZUc=rn3qS0J8ZrAy52BPjAzUuMXxuCjW7xp=oi-A@mail.gmail.com>
To: Dirk Schulze <dschulze@adobe.com>
Cc: "Robert O'Callahan" <robert@ocallahan.org>, public-fx <public-fx@w3.org>, www-style list <www-style@w3.org>
On Fri, Dec 27, 2013 at 1:59 AM, Dirk Schulze <dschulze@adobe.com> wrote:
> On Dec 26, 2013, at 11:45 PM, Tab Atkins Jr. <jackalmage@gmail.com> wrote:
>>> On Tue Dec 24 2013 at 11:55:47 AM, Dirk Schulze <dschulze@adobe.com> wrote:
>>> I really wish to have currentColor behave in a way that it does not reveal any secured information.
>>>
>>> If we do not find an agreement, a way to limit the security restriction further would be to the following:
>>>
>>> For feFlood and feDropShadow: If the value for the ‘flood-color’ property computes to ‘inherit’ or ‘currentColor’ the feFlood filter primitive must be marked as tainted.
>>>
>>> For fe*Lighting: If the value for the ‘lighting-color’ property computes to ‘inherit’ or ‘currentColor’ the feFlood filter primitive must be marked as tainted.
>>
>> 'inherit' disappears by computed-value time - it's processed into the value it represents at specified-value time.  <http://dev.w3.org/csswg/css-cascade/#inherit>
>
> I read css3-cascade and still was confused. I wasn’t sure if specified value was the value of the current style sheet or the last value in the cascade. From your explanation it seems to be the latter.

Neither, but I'm not sure what's confusing.  Could you explain?  The
"cascaded value" definition says that the cascaded value is the
declaration that won the cascade.  The following section then says
that the specified value is the cascaded value, but with
initial/inherit/unset (or a lack of cascaded value entirely) processed
away.

"It is the result of putting the cascaded value through the defaulting
processes, guaranteeing that a specified value exists for every
property on every element."

If you can tell me what's confusing about it, I'll try to fix.

>> Note that "flood-color: inherit;" doesn't expose anything, anyway - it resolves to the value of 'flood-color' on the <feFlood>'s parent. It has no connection to the graphics element that uses the filter containing an <feFlood> element.
>
> Not quite right. The parent of <feFlood> could use ‘currentColor’.

Yup, but that means that flood-color on the <feFlood> will computed to
"currentColor", and thus be caught by the general prohibition against
currentColor as a computed value.  There's no need to call out
"inherit" specifically; it just confuses things.

~TJ
Received on Friday, 3 January 2014 21:56:30 UTC

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