On 2/24/25 4:24 PM, Yoav Weiss (@Shopify) wrote:
On Mon, Feb 24, 2025 at 7:18 PM Mike Taylor <miketa...@chromium.org>
wrote:
On 2/21/25 8:33 AM, Yoav Weiss (@Shopify) wrote:
On Thursday, February 20, 2025 at 1:56:59 PM UTC+1 Yoav Weiss wrote:
On Thursday, February 20, 2025 at 11:47:00 AM UTC+1 Yoav
Weiss wrote:
Contact emailsyoavwe...@chromium.org
Explainerhttps://github.com/w3c/webappsec-subresource-integrity/pull/129#:~:text=for%20some%20assets.-,require%2Dsri%2Dfor%20CSP%20directive,-Subresource%2DIntegrity%20
<https://github.com/w3c/webappsec-subresource-integrity/pull/129#:~:text=for%20some%20assets.-,require%2Dsri%2Dfor%20CSP%20directive,-Subresource%2DIntegrity%20>
Specificationhttps://github.com/w3c/webappsec-subresource-integrity/pull/129
<https://github.com/w3c/webappsec-subresource-integrity/pull/129>
The feature and PR were discussed
<https://github.com/w3c/webappsec/blob/main/meetings/2025/2025-02-19-minutes.md#reviving-require-sri-for>
at the WebAppSec WG call.
No objection beyond questions on whether we'd need to
expand this to cover stylesheets as well. We'd be able to
do that in the future (as a separate intent) if needed.
Summary
The `require-sri-for` directive gives developers the
ability to assert that every resource of a given type
needs to be integrity checked. If a resource of that type
is attempted to be loaded without integrity metadata,
that attempt will fail and trigger a CSP violation
report. This intent covers the "script" value of this
directive.
Blink
componentBlink>SecurityFeature>ContentSecurityPolicy
<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ESecurityFeature%3EContentSecurityPolicy%22>
TAG
reviewhttps://github.com/w3ctag/design-reviews/issues/1048
<https://github.com/w3ctag/design-reviews/issues/1048>
TAG review statusPending - No response just yet
Risks
Interoperability and Compatibility
On the compatibility front:
This directive was already implemented in the past, and
there are some developer docs
<https://udn.realityripple.com/docs/Web/HTTP/Headers/Content-Security-Policy/require-sri-for>
that still describe it. The current PR and implementation
did not diverge from the past implementation.
If developers deployed the feature in the past and are
now relying on it */not really working/*, that may result
in surprising breakage. The HTTPArchive shows *0.0011% of
page responses*(178 out of 15760519)have an existing
`require-sri-for` directive. That's an upper bound - only
those that enforce scripts, and have no integrity
attributes on some scripts may get broken.
Doing some more HA digging I found that it's 153 sites, which
is not significantly different.
I downloaded their URLs
<https://docs.google.com/spreadsheets/d/1NlFHLytc8lQcdP5FXXDltKEPQVE0e8oyjw9k1S-9KPI/edit?usp=sharing>
and
started going to these sites with the feature enabled.
Of those 153, 22 had any blocked assets, 9 had broken
functionality or layout and 1 had missing ads.
Non-visiblity broken but blocked sites mostly had their
analytics blocked.
Extrapolating that data brings us to 0.000158% for any
blocked assets, and 0.000065% for broken functionality.
I'm planning to reach out to the broken sites and make them
aware of this change. Many of them seem to be coming from a
single provider (similar site and breakage).
I also found ~3500 sites that have the `require-sri-for` string
in their response bodies (and hence may have it applied).
I put together a script that so far scanned ~1800 of them and
found no blocked assets. So, it seems like the risk is very low
on that front.
Thanks, I appreciate you digging in to understand the possible
risks. My understanding of the compat risk goes something like
(please let me know if I'm missing something):
1. This feature never really shipped, but was implemented behind a
flag.
2. Early adopter developers (or menu framework authors?) added
require-sri-for for some scripts that they wanted to lock down
Tiny correction: they added it to the document's CSP, not specific
scripts.
(to prevent 3rd-party attackers from modifying them, etc).
3. Now, you actually ship the feature.
That means the risks are:
a) Some CDN was compromised at some point, and now some sketchy
scripts will fail to load. Seems like that's security positive,
even if it surprises users or developers.
b) Perhaps more likely, a page was redesigned and they updated
their analytics provider but didn't remember to add hashes. Now
some things don't work.
I suspect it's
c) they added the header but never actually tested with the feature
enabled, as it never shipped.
It seems like they added the CSP header, but never added an
"integrity" attribute to many/most of their scripts.
From your sheet (which is great, thanks), it seems like largest
impact is busted menus. Is this a single library? Or common pattern?
It seems like a common provider. 6 out of the 9 sites with issues are
Canadian health/edu related sites.
Breaking health/edu-releated sites is not good... When broken, is it
cosmetic, or are the links in the menu still accessible? (I see you're
gathering contact info - let me know if you need help with that.)
Assuming we can sort out the menu breakage somehow, I think for the rest
- the best we can do is roll it out and be ready to killswitch if needed.
/Gecko/: No signal
(https://github.com/mozilla/standards-positions/issues/1173
<https://github.com/mozilla/standards-positions/issues/1173>)
/WebKit/: No signal
(https://github.com/WebKit/standards-positions/issues/458
<https://github.com/WebKit/standards-positions/issues/458>)
/Web developers/: Shopify is interested in this. I
suspect PCIv4
<https://docs.google.com/document/d/1RcUpbpWPxXTyW0Qwczs9GCTLPD3-LcbbhL4ooBUevTM/edit?tab=t.0>
would
make some developers interested in making sure their
documents' scripts have complete integrity checks.
/Other signals/:
WebView application risks
Does this intent deprecate or change behavior of existing
APIs, such that it has potentially high risk for Android
WebView-based applications?
None
Debuggability
None
Will this feature be supported on all six Blink platforms
(Windows, Mac, Linux, ChromeOS, Android, and Android
WebView)?Yes
Is this feature fully tested by web-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?Yes
https://wpt.fyi/results/content-security-policy/tentative/require-sri-for?label=experimental&label=master&aligned
<https://chromium-review.googlesource.com/c/chromium/src/+/5877633>
Flag name on about://flagsNone
Finch feature nameCSPRequireSRIFor
Requires code in //chrome?False
Estimated milestonesShipping on desktop135DevTrial on
desktop134Shipping on Android135DevTrial on
Android134Shipping on WebView135
Anticipated spec changes
Open questions about a feature may be a source of future
web compat or interop issues. Please list open issues
(e.g. links to known github issues in the project for the
feature specification) whose resolution may introduce web
compat/interop risk (e.g., changing to naming or
structure of the API in a non-backward-compatible way).
None
Link to entry on the Chrome Platform
Statushttps://chromestatus.com/feature/5090023365672960?gate=5186570942152704
<https://chromestatus.com/feature/5090023365672960?gate=5186570942152704>
Links to previous Intent discussionsIntent to Prototype:
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohSJUygAmobR9dRkDr%3DBWQ1h5hv2Lj3WUFN31QZF360A47A%40mail.gmail.com
<https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohSJUygAmobR9dRkDr%3DBWQ1h5hv2Lj3WUFN31QZF360A47A%40mail.gmail.com>
This intent message was generated by Chrome Platform
Status <https://chromestatus.com/>.
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