1354331 - Remove network.http.enablePerElementReferrer

Status: RESOLVED FIXED

(Core :: Networking: HTTP, enhancement)

Description

[François Marier [:francois]]

That pref was used to gate the release of per-element referrer policies until the spec was changed to enable this delivery mechanism.

The candidate recommendation of the Referrer Policy spec has it:

  https://www.w3.org/TR/referrer-policy/#referrer-policy-delivery-referrer-attribute

and it has made its way into the HTML spec too:

  https://html.spec.whatwg.org/multipage/infrastructure.html#referrer-policy-attribute

Given that we already have several prefs to trim the referrer (https://feeding.cloud.geek.nz/posts/tweaking-referrer-for-privacy-in-firefox/) and that we don't offer a toggle for document-level referrer policies, this per-element pref is not a meaningful user control mechanism.

Comment 1

[Swapnesh Kumar Sahoo [:swapneshks]]

Hi.. I'm a beginner and would like to take up this bug.
I'm still catching up to things...

Comment 2

[François Marier [:francois]]

(In reply to swapneshks from comment #1)
> Hi.. I'm a beginner and would like to take up this bug.
> I'm still catching up to things...

Feel free to give it a go.

You can start by searching for the name of the pref in https://searchfox.org/ to find out where it's defined and where it's used. From there, you'll get a feel for what needs to change in order to remove it entirely.

Comment 3

[Swapnesh Kumar Sahoo [:swapneshks]]

So I had a look at the usages and found that the pref is being declared at 

https://searchfox.org/mozilla-central/source/modules/libpref/init/all.js#1548

I tried commenting out the above line, but I am not sure how to check whether the action took any effect.
Also, regarding the pref usages, I have the following doubts:

1. Let's pick https://searchfox.org/mozilla-central/source/browser/base/content/browser.js#5821. Do I have to remove only the referrer condition or the entire block?
2. After removal of the pref usage, how do I test whether it took effect?

Comment 4

[Valentin Gosu [:valentin] (he/him)]

So these are all the instances of the pref:
https://searchfox.org/mozilla-central/search?q=network.http.enablePerElementReferrer&path=

(In reply to Swapnesh Kumar Sahoo [:swapneshks] from comment #3)
> 1. Let's pick
> https://searchfox.org/mozilla-central/source/browser/base/content/browser.
> js#5821. Do I have to remove only the referrer condition or the entire block?

All instances of the pref would become true. So

if (Services.prefs.getBoolPref("network.http.enablePerElementReferrer") &&
      linkNode) {

would become

if (linkNode) {

Also, in webidl files, [SetterThrows, Pref="network.http.enablePerElementReferrer"] becomes [SetterThrows]

> 2. After removal of the pref usage, how do I test whether it took effect?

I don't think there is much to check. Just make all the changes, submit the patch, and we'll make sure all the tests are still passing.

Comment 5

[Swapnesh Kumar Sahoo [:swapneshks]]

Attachment: Remove network.http.enablePerElementReferrer usages

Do let me know if I went wrong anywhere/further changes to be made.

Comment 6

[Valentin Gosu [:valentin] (he/him)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=91140a1cf3b4f23263b41aa5548216c8f1a2eb53

Comment 7

[Valentin Gosu [:valentin] (he/him)]

Comment on attachment 8863260 [details] [diff] [review]
Remove network.http.enablePerElementReferrer usages

Review of attachment 8863260 [details] [diff] [review]:
-----------------------------------------------------------------

You missed one instance at:
http://searchfox.org/mozilla-central/source/browser/base/content/content.js#530

Comment 8

[Swapnesh Kumar Sahoo [:swapneshks]]

Attachment: Remove network.http.enablePerElementReferrer usages

Patch with changes added for earlier missed instance.

Comment 9

[Valentin Gosu [:valentin] (he/him)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=5b3ce802151165c85336a2e10410feb88e72d5c1

Comment 10

[Valentin Gosu [:valentin] (he/him)]

Comment on attachment 8863261 [details] [diff] [review]
Remove network.http.enablePerElementReferrer usages

Review of attachment 8863261 [details] [diff] [review]:
-----------------------------------------------------------------

Looks good. Thank you for your contribution!

Comment 11

[Swapnesh Kumar Sahoo [:swapneshks]]

(In reply to Valentin Gosu [:valentin] (Vacation until May 1st) from comment #10)
> Comment on attachment 8863261 [details] [diff] [review]
> Remove network.http.enablePerElementReferrer usages
> 
> Review of attachment 8863261 [details] [diff] [review]:
> -----------------------------------------------------------------
> 
> Looks good. Thank you for your contribution!

My pleasure! 
This is my first accepted patch... Feels great!

Comment 12

[Ryan VanderMeulen [:RyanVM]]

WebIDL changes need DOM peer review before they can land.

Comment 13

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/0041706d6e43
Remove network.http.enablePerElementReferrer usages. r=valentin r=baku

Comment 14

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/0041706d6e43