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First-party isolation in Firefox: what breaks if you enable it?

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Re: First-party isolation in Firefox: what breaks if you enable it?

#11

> I’m not sure whether that is because Mozilla consider it unsafe, unpractical, or don’t want to commit to maintain the feature in future releases. I imagine it was implemented for the container tabs.

FPI was implemented (and enabled by default) in the Tor project and ported upstream back into Firefox. Container tabs is a side-product from that effort.

Re: First-party isolation in Firefox: what breaks if you enable it?

#12
post #8

I guess trackers will just ask websites to route analytics traffic through their own infrastructure. Would it be enough for example.com to setup a dns alias pointing tracking.example.com to tracking.com?

That breaks cross-domain tracking, though; before, cookies set on analytics.com (pulled on SiteA) would be sent back to them when pulled from SiteB. If you now use different domains on each site, that doesn't work.

(To be clear, I think this is a good thing)

Re: First-party isolation in Firefox: what breaks if you enable it?

#13
post #8

I guess trackers will just ask websites to route analytics traffic through their own infrastructure. Would it be enough for example.com to setup a dns alias pointing tracking.example.com to tracking.com?

This would be already a giant leap forward: Usually, there is not a lot of trust between actors, and there doesn't need to be: everyone gets their own tracking pixel and is happy, who cares if user data is leaked along the way. The setup you describe requires more trust beetween parties, and, as a side-effect, reduces the overall number of potential contractual partners which get access to user data. It also reduces the number of websites with the knowledge to implement such a setup.

Re: First-party isolation in Firefox: what breaks if you enable it?

#14

I've been running at home and at work with first-party isolation enabled for a few months now. Google login works fine for me, as does login with Google. It's broken a few internal tools, especially when people do things like hotlink across internal systems (which would have been broken at least some of the time for most people anyway, until they realise that to view _this_ page properly they need to log in over _the…

I’d appreciate a ‘New Temporary Non-Isolated Window’ for use with websites that don’t work with FPI.

Re: First-party isolation in Firefox: what breaks if you enable it?

#15

> I’m not sure whether that is because Mozilla consider it unsafe, unpractical, or don’t want to commit to maintain the feature in future releases. I imagine it was implemented for the container tabs.

The main problem I see with account containers — still — is that you can't say "this container can only have certain websites in it". For example, if you put reddit in a "social" container, but click on links to the stories, then you have all of your cookies and stuff polluting the social container.

I feel like the cause is most likely that there are just too many darn websites for a user to be willing to specify them all. Solving this would seem to require some global database of "all sites run by company X" that undergoes constant maintenance.

Re: First-party isolation in Firefox: what breaks if you enable it?

#16
post #8

I guess trackers will just ask websites to route analytics traffic through their own infrastructure. Would it be enough for example.com to setup a dns alias pointing tracking.example.com to tracking.com?

That breaks cross-domain tracking, though; before, cookies set on analytics.com (pulled on SiteA) would be sent back to them when pulled from SiteB. If you now use different domains on each site, that doesn't work. (To be clear, I think this is a good thing)

Except all the analytics company has to do is have another shred of evidence that your identy is linked and it can just give out tokens that represent opauqe blobs you take care of and index by it's token like PHP does session storage.

Re: First-party isolation in Firefox: what breaks if you enable it?

#17

I've been running at home and at work with first-party isolation enabled for a few months now. Google login works fine for me, as does login with Google. It's broken a few internal tools, especially when people do things like hotlink across internal systems (which would have been broken at least some of the time for most people anyway, until they realise that to view _this_ page properly they need to log in over _the…

The best strategy is to not use Google however. It's not like you need to in 2018 anymore. There are better services for almost anything out there, although you may have to pay a few dollars for some of them. Well worth it since they are superior to Google. For email, Fastmail is king.

For many people (like me) this is not advice that can followed since many many companies use G Suite.

Re: First-party isolation in Firefox: what breaks if you enable it?

#19

> I’m not sure whether that is because Mozilla consider it unsafe, unpractical, or don’t want to commit to maintain the feature in future releases. I imagine it was implemented for the container tabs.

If you enable FPI, is there any benefit to also using container tabs? That is, assuming that you aren't using containers to allow you to log in to the same website with different accounts, but rather to keep data from different websites separate?

Re: First-party isolation in Firefox: what breaks if you enable it?

#20
post #9
post #8

I guess trackers will just ask websites to route analytics traffic through their own infrastructure. Would it be enough for example.com to setup a dns alias pointing tracking.example.com to tracking.com?

This is a possible work-around, but it adds a lot of complexity to get HTTPS and stuff worked-around. Either the third-party must handle HTTPS for their partners who setup CNAMEs, or the first-party must handle HTTPS and proxy the requests back to the third-party. It’s doable but it will significantly slow things down to the point where even shitty websites would consider it unacceptable.

The third-party can handle HTTPS just for that particular subdomain, using a separate certificate.
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