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Define sharable scheme + check #244

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Merged
merged 7 commits into from
Jul 7, 2022
Merged

Define sharable scheme + check #244

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d95dd15
Define sharable scheme + check
marcoscaceres Jul 1, 2022
277339c
fixup: s/ol/ul
marcoscaceres Jul 1, 2022
fad97d5
Clean up Priv/Sec to match
marcoscaceres Jul 1, 2022
6af96aa
remove data
marcoscaceres Jul 1, 2022
2f73158
Explicitly ban file, javascript, wss, local scheme
marcoscaceres Jul 1, 2022
2d9438a
Update index.html
marcoscaceres Jul 1, 2022
a634c92
Merge branch 'main' into schemes
marcoscaceres Jul 7, 2022
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46 changes: 30 additions & 16 deletions index.html
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Original file line number Diff line number Diff line change
Expand Up @@ -385,6 +385,19 @@ <h3>
<h3>
Validate share data
</h3>
<p>
A <dfn>sharable scheme</dfn> is any of the following [=URL=]
[=URL/schemes=]:
</p>
<ul>
<li>`http`
</li>
<li>`https`
</li>
<li>Any [=safelisted scheme=] that the user agent supports for the
purpose of sharing.
</li>
</ul>
<p>
To <dfn>validate share data</dfn> with |data:ShareData| and
|base:URL|, run the following steps:
Expand Down Expand Up @@ -427,13 +440,11 @@ <h3>
</li>
<li>If |url| is failure, return false.
</li>
<li>
<p>
If |url| is a URL the user agent deems potentially hostile
(e.g., "file:") or wouldn't make sense to outside the scope
of the document (e.g., "blob:"), return false.
</p>
<aside class="issue" data-number="178"></aside>
<li>If the |url|'s [=URL/scheme=] is a [=local scheme=], or
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I know this check is kinda redundant, because they are not in the the "sharable scheme" list, but I wanted to be explicit in banning them.

`file`, or `javascript`, or `ws`, or `wss`, return false.
</li>
<li>If |url|'s [=URL/scheme=] is not a [=sharable scheme=],
return false.
</li>
</ol>
</li>
Expand Down Expand Up @@ -592,10 +603,13 @@ <h2>
Security and privacy considerations
</h2>
<p>
Web Share enables data to be sent from websites to native applications.
While this ability is not unique to Web Share, it does come with a
number of potential security issues that can vary in severity
(depending on the underlying platform).
Web Share enables data to be sent from websites to a [=share target=],
which can be a native applications. While this ability is not unique to
Web Share, it does come with a number of potential security risks that
can vary in severity (depending on the underlying platform).
</p>
<p>
The following points are worth considering:
</p>
<ul>
<li>The API does not expose to the website which [=share targets=] are
Expand Down Expand Up @@ -641,11 +655,11 @@ <h2>
buffer overflow or other remote code execution vulnerabilities in
native applications that receive shares. There is no general way to
guard against this, but implementors will want to be aware that it is a
possibility.
possibility (particularly when sharing files).
</li>
<li>
<p>
Share targets that dereference a shared URL and forward that
[=Share targets=] that dereference a shared URL and forward that
information on might inadvertently forward information that might
be otherwise confidential. This can lead to unexpected information
leakage if shares reference content that is only accessible by that
Expand All @@ -656,9 +670,9 @@ <h2>
by providing URLs that ultimately resolve to local resources,
including, but not limited to, "file:" URLs or local services that
might otherwise be inaccessible. Even though this API limits shared
URLS to "http:" and "https:", use of redirects to other URLs or
tweaks to DNS records for hosts in those URLs might be used to
cause applications to acquire content.
URLS to a restricted set of [=sharable schemes=], use of redirects
to other URLs or tweaks to DNS records for hosts in those URLs
might be used to cause applications to acquire content.
</p>
<p>
To avoid being used in these attacks, share targets can consume the
Expand Down