1930500 - Restore `Clear-Site-Data: cache` functionality

Status: RESOLVED FIXED

(Toolkit :: Data Sanitization, enhancement, P2)

Description

[Manuel Bucher [:manuel] {{ fyi: PTO Jul 26 - Aug 17 }}]

With https://github.com/privacycg/storage-partitioning/issues/11 addressed (within Firefox) and concerns for Webcompat breakage, we want to restore the feature again.

Comment 1

[Manuel Bucher [:manuel] {{ fyi: PTO Jul 26 - Aug 17 }}]

Attachment: Bug 1930500 - Enable `Clear-Site-Data: "cache"` in all channels r=#anti-tracking

This reverts:

• https://hg.mozilla.org/mozilla-central/rev/38854fb7f44e
• https://hg.mozilla.org/mozilla-central/rev/3df455e2d5a8

Comment 2

[Sebastian Zartner [:sebo]]

Manuel, if I understand this bug correctly, once your patch lands, Clear-Site-Data: cache will be generally available again without being put behind a pref. Correct?

If so, the related browser compat data needs to be updated. Otherwise, it should be added to the Experimental Features page.

Sebastian

Comment 3

[Manuel Bucher [:manuel] {{ fyi: PTO Jul 26 - Aug 17 }}]

Hi. Yes. However I haven't gotten around to adding tests. There didn't exist any when the feature landed previously. I'm looking into writing some web-platform tests, but haven't gotten around doing that just yet.

I'll slightly switch the strategy for the patch and introduce a pref (enabled by default), due to complications our current indexing within the http cache making it necessary to iterate through all files. This is a really expensive operation. I'm investigating the performance impact and possible strategies to mitigate the problem.

Comment 4

[Manuel Bucher [:manuel] {{ fyi: PTO Jul 26 - Aug 17 }}]

I'd wait for whether Bug 1950058 lands as planned, but would then proceed to enable Clear-Site-Data: "cache" network cache cleaning for all channels. (And start necessary work for release notes + intent-to-ship)

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/0bfba221c8bd
Enable `Clear-Site-Data: "cache"` in all channels r=anti-tracking-reviewers,timhuang

Comment 6

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/0bfba221c8bd

Comment 7

[Manuel Bucher [:manuel] {{ fyi: PTO Jul 26 - Aug 17 }}]

Release Note Request (optional, but appreciated)
[Why is this notable]: More webcompat.
[Affects Firefox for Android]: Yes
[Suggested wording]: Firefox enables the "cache" directive for the "Clear-Site-Data" header, allowing websites to clear the networking cache. The header gives websites more control over data stored for their users, such as clearing the network cache during logout, mitigating the risk of privacy leaks.
[Links (documentation, blog post, etc)]: Spec / Doc links related to this feature:

• https://www.w3.org/TR/clear-site-data/#clear-cache
• https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Clear-Site-Data

Comment 8

[Dianna Smith [:diannaS]]

Added to 138 nightly release notes and is on track for the final 138 release notes

Comment 9

[Hamish Willee]

FF138 MDN docs for this can be tracked in https://github.com/mdn/content/issues/38909 - just a release note, removal from experimental data, and updating the compatibility data.