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Integrate Trusted Types enforcement into attribute handling #1268

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aa3fe7e
Trusted Types
lukewarlow Apr 24, 2025
526f422
Revert change to "set an attribute value"
lukewarlow Apr 24, 2025
00d0eaa
Update setAttributeNS to include TT check
lukewarlow Apr 24, 2025
f5e3984
Remove extra algorithm that called through to TT and call TT directly…
lukewarlow Jun 25, 2025
df2bccd
Revert larger change to setAttributeNs as its no longer neccessary.
lukewarlow Jul 3, 2025
eb1b546
Set attr's value to verifiedValue before attribute change steps are f…
lukewarlow Jul 3, 2025
1e3cef8
Replace this with originalElement inside set an existing attribute value
lukewarlow Sep 30, 2025
6fe40a3
Rename originalElement to just element
lukewarlow Sep 30, 2025
78773d9
Swap element for this in setAttributeNs
lukewarlow Oct 28, 2025
f3148ed
Drop abstract-op and fix associated formatting
lukewarlow Oct 28, 2025
383d39c
Rename tt algorithm
lukewarlow Oct 28, 2025
2075acd
Remove early return when setting an existing attribute value and the …
lukewarlow Oct 30, 2025
1ff8aaa
modernize some of the old prose and lean on early returns
annevk Oct 30, 2025
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55 changes: 45 additions & 10 deletions dom.bs
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Original file line number Diff line number Diff line change
Expand Up @@ -50,9 +50,11 @@ spec:html; type:element
<p>This specification depends on the Infra Standard. [[!INFRA]]

<p>Some of the terms used in this specification are defined in <cite>Encoding</cite>,
<cite>Selectors</cite>, <cite>Web IDL</cite>, <cite>XML</cite>, and <cite>Namespaces in XML</cite>.
<cite>Selectors</cite>, <cite>Trusted Types</cite>, <cite>Web IDL</cite>, <cite>XML</cite>, and
<cite>Namespaces in XML</cite>.
[[!ENCODING]]
[[!SELECTORS4]]
[[!TRUSTED-TYPES]]
[[!WEBIDL]]
[[!XML]]
[[!XML-NAMES]]
Expand Down Expand Up @@ -6633,8 +6635,8 @@ interface Element : Node {
sequence&lt;DOMString> getAttributeNames();
DOMString? getAttribute(DOMString qualifiedName);
DOMString? getAttributeNS(DOMString? namespace, DOMString localName);
[CEReactions] undefined setAttribute(DOMString qualifiedName, DOMString value);
[CEReactions] undefined setAttributeNS(DOMString? namespace, DOMString qualifiedName, DOMString value);
[CEReactions] undefined setAttribute(DOMString qualifiedName, (TrustedType or DOMString) value);
[CEReactions] undefined setAttributeNS(DOMString? namespace, DOMString qualifiedName, (TrustedType or DOMString) value);
[CEReactions] undefined removeAttribute(DOMString qualifiedName);
[CEReactions] undefined removeAttributeNS(DOMString? namespace, DOMString localName);
[CEReactions] boolean toggleAttribute(DOMString qualifiedName, optional boolean force);
Expand Down Expand Up @@ -7115,6 +7117,11 @@ string <var>namespace</var> (default null):</p>
<a for=/>attribute</a> <var>attr</var> and an <a for=/>element</a> <var>element</var>:

<ol>
<li><p>Let <var>verifiedValue</var> be the result of calling <a abstract-op>get
Trusted Types-compliant attribute value</a> with <var>attr</var>'s <a for=Attr>local name</a>,
<var>attr</var>'s <a for=Attr>namespace</a>, <var>element</var>, and <var>attr</var>'s
<a for=Attr>value</a>. [[!TRUSTED-TYPES]]

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This is a bit nitpicking, but I think I'd prefer still that passing existing attribute node here would be no-op.
Gecko does attr.element == some other element -> throw, attr == existingAttr return; also before TT check.

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@smaug---- smaug---- Oct 30, 2025 •
edited
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...but I can also live with this proposed algorithm.

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After our discussion I'm going to keep it how it is, tests to ensure Firefox behaviour fails is added here web-platform-tests/wpt#55762

<li><p>If <var>attr</var>'s <a for=Attr>element</a> is neither null nor <var>element</var>,
<a>throw</a> an "{{InUseAttributeError!!exception}}" {{DOMException}}.

Expand All @@ -7125,6 +7132,8 @@ string <var>namespace</var> (default null):</p>

<li><p>If <var>oldAttr</var> is <var>attr</var>, return <var>attr</var>.

<li><p>Set <var>attr</var>'s <a for=Attr>value</a> to <var>verifiedValue</var>.

<li><p>If <var>oldAttr</var> is non-null, then <a lt="replace an attribute">replace</a>
<var>oldAttr</var> with <var>attr</var>.

Expand Down Expand Up @@ -7414,17 +7423,21 @@ method steps are:
<a>HTML document</a>, then set <var>qualifiedName</var> to <var>qualifiedName</var> in
<a>ASCII lowercase</a>.

<li><p>Let <var>verifiedValue</var> be the result of calling <a abstract-op>get
Trusted Types-compliant attribute value</a> with <var>qualifiedName</var>, null, <a>this</a>, and
<var>value</var>. [[!TRUSTED-TYPES]]

<li><p>Let <var>attribute</var> be the first <a>attribute</a> in <a>this</a>'s
<a for=Element>attribute list</a> whose <a for=Attr>qualified name</a> is <var>qualifiedName</var>,
and null otherwise.
<!-- This is step 2 of "get an attribute by name", modified as appropriate -->

<li><p>If <var>attribute</var> is null, create an <a>attribute</a> whose
<a for=Attr>local name</a> is <var>qualifiedName</var>, <a for=Attr>value</a> is
<var>value</var>, and <a for=Node>node document</a> is <a>this</a>'s <a for=Node>node document</a>,
then <a lt="append an attribute">append</a> this <a>attribute</a> to <a>this</a>, and then return.
<var>verifiedValue</var>, and <a for=Node>node document</a> is <a>this</a>'s
<a for=Node>node document</a>, then <a lt="append an attribute">append</a> this <a>attribute</a>
to <a>this</a>, and then return.

<li><p><a lt="change an attribute">Change</a> <var>attribute</var> to <var>value</var>.
<li><p><a lt="change an attribute">Change</a> <var>attribute</var> to <var>verifiedValue</var>.
</ol>

<p>The
Expand All @@ -7436,8 +7449,12 @@ method steps are:
[=validate and extract|validating and extracting=] <var>namespace</var> and
<var>qualifiedName</var> given "<code>element</code>".

<li><p><a>Set an attribute value</a> for <a>this</a> using <var>localName</var>, <var>value</var>,
and also <var>prefix</var> and <var>namespace</var>.
<li><p>Let <var>verifiedValue</var> be the result of calling <a abstract-op>get
Trusted Types-compliant attribute value</a> with <var>localName</var>, <var>namespace</var>,
<var>element</var>, and <var>value</var>. [[!TRUSTED-TYPES]]

<li><p><a>Set an attribute value</a> for <a>this</a> using <var>localName</var>,
<var>verifiedValue</var>, and also <var>prefix</var> and <var>namespace</var>.
</ol>

<p>The
Expand Down Expand Up @@ -8028,7 +8045,25 @@ string <var>value</var>, run these steps:
<li><p>If <var>attribute</var>'s <a for=Attr>element</a> is null, then set <var>attribute</var>'s
<a for=Attr>value</a> to <var>value</var>.

<li><p>Otherwise, <a lt="change an attribute">change</a> <var>attribute</var> to <var>value</var>.
<li>
<p>Otherwise:

<ol>
<li><p>Let <var>element</var> be <var>attribute</var>'s <a for=Attr>element</a>.

<li><p>Let <var>verifiedValue</var> be the result of calling <a abstract-op>get
Trusted Types-compliant attribute value</a> with <var>attribute</var>'s
<a for=Attr>local name</a>, <var>attribute</var>'s <a for=Attr>namespace</a>,
<var>element</var>, and <var>value</var>. [[!TRUSTED-TYPES]]

<li><p>If <var>attribute</var>'s <a for=Attr>element</a> is null, then set <var>attribute</var>'s
<a for=Attr>value</a> to <var>verifiedValue</var>, and return.

<li><p>If <var>attribute</var>'s <a for=Attr>element</a> is not <var>element</var>, then
return.
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Gecko doesn't have this check. Hmm, and actually, the API becomes a bit surprising with this check. One is trying to change the value, but nothing happens. No exception, and value isn't changed.

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So, I would drop this check. no-op isn't good, and if TT callback has moved the attribute, then it has. We need to trust TT callbacks in that sense.

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I've gone ahead and removed that early return. After our discussions. web-platform-tests/wpt#55762 - test updated here.

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cc @otherdaniel just as an fyi there is a minor change to make to the Attr.nodeValue case.


<li><p><a lt="change an attribute">Change</a> <var>attribute</var> to <var>verifiedValue</var>.
</ol>
</ol>

<p>The {{Attr/value}} setter steps are to <a>set an existing attribute value</a> with <a>this</a>
Expand Down