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Add new trusted-eval source expression to 'script-src' directive. #473

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Add new trusted-eval source expression to 'script-src' directive. #473

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44 changes: 37 additions & 7 deletions spec/index.bs
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Original file line number Diff line number Diff line change
Expand Up @@ -1639,6 +1639,29 @@ Content-Security-Policy: trusted-types one two default
</pre>
</div>

### <dfn lt="trusted-eval-source">trusted-eval</dfn> source ### {#trusted-eval-csp-source}

This document defines *trusted-eval* - a new [=source expression=]. The [=trusted-eval-source|trusted-eval=] source can be used to allow evaluation of trusted code. Without
the use of "<a grammar>`'unsafe-eval'`</a>".

Note: This source expression is used to allow usage of eval in environments protected by trusted types, without allowing the uncontrolled use of eval
in environments that don't have trusted types supported and enabled.

<pre dfn-type="grammar" link-type="grammar">
keyword-source = "'self'" / "'unsafe-inline'" / "'unsafe-eval'"
/ "'strict-dynamic'" / "'unsafe-hashes'" /
/ "'report-sample'" / "'unsafe-allow-redirects'"
/ "'wasm-unsafe-eval'"<ins> / "<dfn>'trusted-eval'</dfn>"</ins>
</pre>

<div class="example" id="trusted-eval-script-src">
To use trusted-eval, the following header is required:

<pre class="http">
Content-Security-Policy: require-trusted-types-for 'script'; script-src 'trusted-eval'
</pre>
</div>

### <dfn abstract-op>Does sink type require trusted types?</dfn> ### {#does-sink-require-trusted-types}

Given a [=realm/global object=] (|global|), a string (|sinkGroup|) this algorithm
Expand Down Expand Up @@ -1779,6 +1802,9 @@ throws an "`EvalError`" if not:

1. <ins>If |sourceString| is not equal to |source|, throw an {{EvalError}}.</ins>

1. <ins>Let |requireTrustedTypes| be the result of executing [$Does sink type require trusted types?$] algorithm,
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As currently written this doesn't deal with the case where script-src is in enforcement mode but requre-trusted-types-for isn't.

passing |calleeRealm|, and `'script'`.</ins>

1. Let |global| be a |calleeRealm|'s [=realm/global object=].

1. Let |result| be "`Allowed`".
Expand All @@ -1787,28 +1813,32 @@ throws an "`EvalError`" if not:

1. Let |source-list| be `null`.

2. If |policy| contains a [=directive=] whose [=directive/name=] is "`script-src`", then
1. If |policy| contains a [=directive=] whose [=directive/name=] is "`script-src`", then
set |source-list| to that [=directive=]'s [=directive/value=].

Otherwise if |policy| contains a [=directive=] whose [=directive/name=] is
"`default-src`", then set |source-list| to that directive's [=directive/value=].

3. If |source-list| is not `null`, and does not contain a [=source expression=] which is
an [=ASCII case-insensitive=] match for the string "<a grammar>`'unsafe-eval'`</a>" then:
1. If |source-list| is not `null`, then:
1. <ins>If |requireTrustedTypes| and |source-list| contains a [=source expression=] which is
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Perhaps rather than doing the requireTrustedTypes check here, we should use trusted-eval as an enforcement mechanism. So it implies require-trusted-types-for in the eval context?

Not sure if that's good or bad just an idea.

an [=ASCII case-insensitive=] match for the string "<a grammar>`'trusted-eval'`</a>", then skip the following steps.</ins>

1. If |source-list| contains a [=source expression=] which is
an [=ASCII case-insensitive=] match for the string "<a grammar>`'unsafe-eval'`</a>", then skip the following steps.

1. Let |violation| be the result of executing [[CSP3#create-violation-for-global]] on
|global|, |policy|, and "`script-src`".

2. Set |violation|'s [=violation/resource=] to "`inline`".
1. Set |violation|'s [=violation/resource=] to "`inline`".

3. If |source-list| [=list/contains=] the expression
1. If |source-list| [=list/contains=] the expression
"<a grammar>`'report-sample'`</a>", then set |violation|'s [=violation/sample=] to
the substring of <del>|source|</del> <ins>|sourceString|</ins> containing its first
40 characters.

4. Execute [[CSP3#report-violation]] on |violation|.
1. Execute [[CSP3#report-violation]] on |violation|.

5. If |policy|'s [=policy/disposition=] is "`enforce`", then set |result| to
1. If |policy|'s [=policy/disposition=] is "`enforce`", then set |result| to
"`Blocked`".

1. If |result| is "`Blocked`", throw an `EvalError` exception.
Expand Down
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