1769028 - nsProfileLock::LockWithSymlink should not perform DNS requests when the proxy bypass protection is enabled

Status: RESOLVED FIXED

(Toolkit :: Startup and Profile System, defect)

Description

[Pier Angelo Vendrame]

Attachment: This is the path for Firefox 91.9.0 ESR that we use on Tor Browser

nsProfileLock::LockWithSymlink performs a DNS lookup of the current system hostname, to get the IP address to add it to the symlink name.

We think that if proxy bypass protection is enabled, this function should always use 127.0.0.1.

Basically, the change would be putting the part of code that performs the DNS query under an #ifndef MOZ_PROXY_BYPASS_PROTECTION.

We have had a patch that just removed the DNS query in Tor Browser for many years. It was originally developed by Kathy Brade, who found it could be troublesome when the following conditions are all true:

1. The browser profile is on a network file system.
2. The file system does not support fcntl() locking.
3. The browser is run from two different computers at the same time.

However, we think that honoring MOZ_PROXY_BYPASS_PROTECTION has higher precedence than preventing this scenario.

Thanks!

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:mossop, could you have a look please?

For more information, please visit auto_nag documentation.

Comment 2

[Pier Angelo Vendrame]

Hello, I could open a phabricator request with the patch I have already attached.
Could I set you as a reviewer, in case? Otherwise, who could I set?
Thanks in advance!

Comment 3

[Dave Townsend [:mossop]]

(In reply to Pier Angelo Vendrame from comment #2)

Hello, I could open a phabricator request with the patch I have already attached.
Could I set you as a reviewer, in case? Otherwise, who could I set?
Thanks in advance!

Sorry missed this somehow. Yes you can set me as reviewer.

Comment 4

[Pier Angelo Vendrame]

Attachment: Bug 1769028: Disable DNS lookup in nsProfileLock when the proxy bypass protection is enabled r=mossop

Instead of using the local computer's IP address within
symlink-based profile lock signatures, always use 127.0.0.1 when the
proxy bypass protection is enabled.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/b8451510594b
Disable DNS lookup in nsProfileLock when the proxy bypass protection is enabled r=mossop

Comment 6

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/b8451510594b