Add a setting for allowing .onion requests in normal windows

[fmarier]

In #32108, we blocked all network requests to .onion URLs outside of Tor windows. Such network request will fail due to the need to use the tor proxy in order to resolve and connect to them, but before failing they will leak the name of the Onion services to the DNS resolver.

One use case we had not anticipated however was people installing the tor daemon on their (likely OpenWRT or Pi-hole-based) router and then letting all local clients resolve and connect to .onion normally outside of Tor windows (or in fact outside of Brave too).

The proposed fix is to add a setting in brave://settings/privacy under Tor windows:

Only resolve .onion addresses in Tor windows
Onion services will not be available outside of Tor windows.

The toggle will be on by default, in line with the RFC 7686 recommendation:

Applications that do not implement the Tor protocol SHOULD generate an error upon the use of .onion and SHOULD NOT perform a DNS lookup.

In addition, we should add a devtools console warning pointing to this setting when we block a network request for this reason.

[fmarier]

Noting that this is a problem with cURL as well and that this transparent proxying of .onion services is considered "ill-advised".

We'll still add the setting for users who want this use-case to work, but the default behavior will remain the same.

[hisenb3rg]

Hi, do we have any ETA on this?

It is really annoying because I cannot use Brave if it updates (at restart)... there's no way to pin to last version when this worked...

[fmarier]

@jurglic I am currently working on this and I expect it will ship with Brave 1.62.

[stephendonner]

Verification PASSED using

Brave | 1.62.93 Chromium: 120.0.6099.35 (Official Build) beta (x86_64)
-- | --
Revision | 2032da61e85b8d826ab474ee36fee9a9cee09907
OS | macOS Version 11.7.10 (Build 20G1427)

Steps:

1. installed 1.62.93
2. launched Brave
3. skipped onboarding
4. opened brave://settings/privacy and confirmed that Only resolve .onion in Tor windows was Enabled by defaullt
5. opened the developer tools and focused the Console pane
6. loaded https://fmarier.github.io/brave-testing/onion-subresource-33735.html and confirmed the broken image
7. confirmed the error for onion16.png is net::ERR_BLOCKED_BY_CLIENT
8. opened brave://settings/privacy and disabled Only resolve .onion in Tor windows
9. cleared the devtools console
10. force-refreshed the page and confirmed broken image
11. confirmed the error for onion16.png is now net::ERR_NAME_NOT_RESOLVED
12. repeated the above steps in a Private Window with Tor window (12a = pref on, 12b = pref off)

Confirmed that the image loads in a Tor window, regardless of the Only resolve .onion in Tor windows preference

Also confirmed the Learn more link which points to https://support.brave.com/hc/en-us/articles/360018121491-What-is-a-Private-Window-with-Tor-Connectivity-

step 4	step 6	step 7	step 8	steps 10-11	step 12a	step 12b	Learn more, a	Learn more, b

[MadhaviSeelam]

Verification PASSED using

Brave | 1.62.104 Chromium: 120.0.6099.71 (Official Build) beta (64-bit)
-- | --
Revision | e2b266991247b909fa88520bb12d018223872d29
OS | Windows 11 Version 22H2 (Build 22621.2715)

1. installed 1.62.104
2. launched Brave
3. skipped onboarding
4. opened brave://settings/privacy and confirmed that Only resolve .onion in Tor windows was Enabled by defaullt
5. opened the developer tools and focused the Console pane
6. loaded https://fmarier.github.io/brave-testing/onion-subresource-33735.html and confirmed the broken image
7. confirmed the error for onion16.png is net::ERR_BLOCKED_BY_CLIENT
8. opened brave://settings/privacy and disabled Only resolve .onion in Tor windows
9. cleared the devtools console
10. force-refreshed the page and confirmed broken image
11. confirmed the error for onion16.png is now net::ERR_NAME_NOT_RESOLVED
12. repeated the above steps in a Private Window with Tor window pref = on
    13 repeated above steps in a Private Window with Tor window with pref = off

step 4	step 6-7	step 8	step 11

step 12a	step 12b	step 13 a	step 13b

[LaurenWags]

Verified with

Brave	1.62.112 Chromium: 120.0.6099.115 (Official Build) beta (64-bit) 
Revision	ae1e179b9884b2de2f4ba0bdea7da3beaad93ffa
OS	Linux

Steps:

1. installed 1.62.x
2. launched Brave
3. skipped onboarding
4. opened brave://settings/privacy and confirmed that Only resolve .onion in Tor windows was Enabled by default
5. opened the developer tools and focused the Console pane
6. loaded https://fmarier.github.io/brave-testing/onion-subresource-33735.html and confirmed the broken image
7. confirmed the error for onion16.png is net::ERR_BLOCKED_BY_CLIENT
8. opened brave://settings/privacy and disabled Only resolve .onion in Tor windows
9. cleared the devtools console
10. force-refreshed the page and confirmed broken image
11. confirmed the error for onion16.png is now net::ERR_NAME_NOT_RESOLVED
12. repeated the above steps in a Private Window with Tor window (12a = pref on, 12b = pref off)

step 4	step 6	step 7	step 8	steps 10-11

Confirmed that the image loads in a Tor window, regardless of the Only resolve .onion in Tor windows preference

Pref On	step 12a	Pref Off	step 12b

Also confirmed that the first setting under Tor windows in brave://settings/privacy has a Learn more link which directs to https://support.brave.com/hc/en-us/articles/360018121491-What-is-a-Private-Window-with-Tor-Connectivity-

Learn more	Learn more

[king-11]

thanks for this feature. I am having trouble in finding a a way to add proxy configuration to redirect onion URL resolution to tor service running locally using a .pac file like this:

function FindProxyForURL(url, host)
{
  if (shExpMatch(host, "*.onion"))
  {
    return "SOCKS5 127.0.0.1:9050";
  }
  return "DIRECT";
}

function FindProxyForURLEx(url, host) {
  return FindProxyForURL(url, host);
}

[fmarier]

@king-11 You may want to file a separate issue for this since it's either a separate feature request, or a bug for something that should already work as part of the PAC support.

[king-11]

Sure thanks @fmarier