858116 - Make each window opened in "Private Browsing Mode" a separate process

Status: RESOLVED WONTFIX

(Firefox :: Private Browsing, enhancement)

Description

[Greg]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:20.0) Gecko/20100101 Firefox/20.0
Build ID: 20130329030832

Steps to reproduce:

Installed v20 Firefox expecting to be able to open more than one Private Browsing window such that each window's "privateness" is independent from the other.


Actual results:

Users cannot open a new Private Browsing window that is separate/disconnected from an already open private browsing window. All private browsing windows that I open share the same cookies--this should not be!




Expected results:

if I open private-browsing-window-1 and login to a site, I should be able to open a second private-browsing-window (private-browsing-window-2) and go to the same site but not be logged in. That is, the cookies are not shared between the two private browsing windows. Each Private Browsing window is "private/independent" of any other private browsing windows. 

this capability has many useful features besides privacy. For example, one use is that a user can login to Hotmail-account-1 in private-browsing-window-1 and then open a second window (private-browsing-window-2) and login to Hotmail-account-2 in that window, which is impossible if window-2 is using the same cookies from window-1.

This is the feature that Firefox v20 should have added to the browser: user enables "Always use private browsing mode" and then he/she can simply tap Ctrl+N to open a new firefox-window as a separate process (that is, the new window will not share cookies, history, etc with any of the other open windows).

Comment 1

[(mostly gone) XtC4UaLL [:xtc4uall]]

FWIW, the "Private Tab" Extension (https://addons.mozilla.org/en-US/firefox/addon/private-tab/) suffers by the same Limitations, though unsure if it's doable at all for Extensions without the Core providing necessary Background/APIs.

Comment 3

[Greg]

I do not feel that the DUPLICATE status this has been resolved to is appropriate. The feature of being able to open new Private Browsing windows and have each new window run in its own process is not just useful for instances where a user might want to sign into multiple accounts. I apologize for not providing more examples in my original write-up.

Opening each session of a Private Browsing window as a separate process has many security/privacy advantages. For example, it would facilitate a good security practice of opening a new Private Browsing window for every "sensitive" web activity--such as online banking. 

A real-world example: a user opens a Private-Browsing window to shop for a birthday gift for a family member. During the browsing session, the user wants to check how much money is available in his/her bank account. So user opens a new Private Browsing window to be used solely for logging into the bank account. The new "separate process" window has no connection to the previous browsing window and hence is more isolated and more secure. Even though the user was using a Private Browsing window to browse the web with (i.e., was shopping for a birthday gift for a family member who also uses the same computer), the user still gains security enhancement when a new private browsing window is opened to log into a bank account because the new private browsing window also opens in a separate process.

Comment 4

[Josh Matthews [:jdm]]

There are huge technical complications involved with multiple processes; we use them on Firefox OS, but they're linked together, and there are no concrete plans to bring that technology to desktop right now. If the separate process concept is the goal of this enhancement request, I'm going to close it, because it's not worth leaving open for something that is both extremely complicated and unlikely to be worked on.

Comment 5

[Greg]

Can Firefox do it without using a "separate process"? 

A separate process would be ideal. But it would still be acceptable to be able to open more than one Private Browsing window and have each window's cookies be separate from the other windows. Users should be able to open a Private Browsing window with expectation that a new window will be "cookie clean."

Currently, if I open a Private Browsing window and accumulate some cookies, those cookies will be "present/active" in a second Private Browsing window. Any way to make 2 or more Private Browsing windows not share the same history/cookies/cache without using separate processes (since separate processes is too complicated for Mozilla to implement)?

I think this feature would be really useful even if it can't be done using separate process.

Comment 6

[Josh Matthews [:jdm]]

Separate "cookie jars" is covered by bug 844672.

Comment 7

[(no longer active)]

Also note that there is nothing in comment 3 or comment 5 which does require use of multiple processes.  That is an implementation detail and just using multiple processes doesn't improve security etc.