Tor ERR_PROXY_CONNECTION_FAILED when network devices change on Linux

[wknapik]

Description

I use Brave on a laptop at home and at work. At home, I use a VPN, at work, I don't. While the non-Tor windows keep working, the Tor window eventually stops working and all tabs in that window report ERR_PROXY_CONNECTION_FAILED on reload. There appears to be no obvious trigger for the breakage, at some random point it just stops working.

Initially, I thought maybe switching between cable and wifi was causing this, but I've been using wifi exclusively for a while and the issue persists.

Steps to Reproduce

1. Open a Tor window.
2. Switch networks, or from VPN to non-VPN, or from non-VPN to VPN (not guaranteed to reproduce the problem).
3. After some time, the Tor connection can no longer be (re)established.

Actual result:

b0rkage.

Expected result:

No b0rkage.

Reproduces how often:

Inconsistently.

Brave version (brave://version info)

Brave	1.2.43 Chromium: 79.0.3945.130 (Official Build) unknown (64-bit)
Revision	e22de67c28798d98833a7137c0e22876237fc40a-refs/branch-heads/3945@{#1047}
OS	Linux
JavaScript	V8 7.9.317.33
Flash	(Disabled)
User Agent	Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36
Command Line	/usr/lib/brave-bin/brave --enable-dom-distiller --disable-domain-reliability --no-pings --extension-content-verification=enforce_strict --extensions-install-verification=enforce --enable-oop-rasterization=Enabled --sync-url=https://no-thanks.invalid --enable-features=PasswordImport,WebUIDarkMode,SimplifyHttpsIndicator --disable-features=AutofillServerCommunication,NotificationTriggers,LookalikeUrlNavigationSuggestionsUI,AudioServiceOutOfProcess,SmsReceiver,WebXR,UnifiedConsent,WebXrGamepadModule,AllowPopupsDuringPageUnload,SyncUSSBookmarks --flag-switches-begin --enable-features=PasswordImport,WebUIDarkMode,SimplifyHttpsIndicator,WebRtcHideLocalIpsWithMdns --disable-features=AutofillServerCommunication,NotificationTriggers,LookalikeUrlNavigationSuggestionsUI,AudioServiceOutOfProcess,SmsReceiver,WebXR,UnifiedConsent,WebXrGamepadModule,AllowPopupsDuringPageUnload,SyncUSSBookmarks,AccountConsistency,WebRTCPipeWireCapturer --flag-switches-end --disable-webrtc-apm-in-audio-service
Executable Path	/usr/lib/brave-bin/brave
Profile Path	/home/redacted/.config/BraveSoftware/Brave-Browser/Default

Brave is installed from an AUR package (PKGBUILD).

Version/Channel Information:

% brave --version
Brave Browser 79.1.2.43 unknown
%

This issue has been present for at least a few versions.

Other Additional Information:

% date
Fri Jan 24 16:35:25 CET 2020
% tail  ~/.config/BraveSoftware/Brave-Browser/tor/data/tor.log
Jan 24 11:26:07.000 [notice] Heartbeat: Tor's uptime is 1 day 23:59 hours, with 8 circuits open. I've sent 34.16 MB and received 66.36 MB.
Jan 24 11:26:07.000 [notice] Average packaged cell fullness: 52.438%. TLS write overhead: 4%
Jan 24 11:30:11.000 [notice] Have tried resolving or connecting to address '[scrubbed]' at 3 different places. Giving up.
Jan 24 11:40:12.000 [notice] Have tried resolving or connecting to address '[scrubbed]' at 3 different places. Giving up.
Jan 24 11:50:14.000 [notice] Have tried resolving or connecting to address '[scrubbed]' at 3 different places. Giving up.
Jan 24 12:00:15.000 [notice] Have tried resolving or connecting to address '[scrubbed]' at 3 different places. Giving up.
Jan 24 12:10:16.000 [notice] Have tried resolving or connecting to address '[scrubbed]' at 3 different places. Giving up.
Jan 24 12:20:16.000 [notice] Have tried resolving or connecting to address '[scrubbed]' at 3 different places. Giving up.
Jan 24 12:30:18.000 [notice] Have tried resolving or connecting to address '[scrubbed]' at 3 different places. Giving up.
Jan 24 12:40:05.000 [notice] Catching signal TERM, exiting cleanly.
%

Miscellaneous Information:

I'm using Arch Linux.

For VPN leak prevention, I use https://github.com/wknapik/vpnfailsafe while the VPN is running and disable it when it's not running (removing routes, firewall rules, hosts entries).

[wknapik]

I'm not seeing the same problem with the Tor Browser.

[bsclifton]

cc: @riastradh-brave

[wknapik]

I should probably add, that closing the Tor window and starting a new one does not solve the problem. The entire browser needs to be closed and started again for Tor to resume working correctly.

[wknapik]

Strace against the tor-0.3.5.8-linux-brave-0 process (pid 3459383, uid 31337) produced

--- SIGTERM {si_signo=SIGTERM, si_code=SI_USER, si_pid=3459340, si_uid=31337} ---

By the time I looked at the process list, the sender was already gone, but the very close pid numbers suggest a related process - something spawned by Brave, rather than something completely unrelated.

[wknapik]

Same/similar issue on macOS #8129.

[wknapik]

I set up an audit rule as follows:

% auditctl -a exit,always -F arch=b64 -F a0="$(pgrep -f /tor)" -S kill -k brave_tor 

then, a few minutes ago, the tor process was killed again and I got the following:

% ausearch -k brave_tor -i                                                         
type=PROCTITLE msg=audit(02/10/20 13:33:42.949:21945) : proctitle=/usr/lib/brave-bin/brave --type=utility --field-trial-handle=2526640678691046932,6475114613948545150,131072 --enable-features=Pa 
type=OBJ_PID msg=audit(02/10/20 13:33:42.949:21945) : opid=4713 oauid=d ouid=d oses=2 ocomm=tor-0.3.5.8-lin 
type=SYSCALL msg=audit(02/10/20 13:33:42.949:21945) : arch=x86_64 syscall=kill success=yes exit=0 a0=0x1269 a1=SIGTERM a2=0x1 a3=0x4000 items=0 ppid=2615 pid=4708 auid=d uid=d gid=d euid=d suid=d fsuid=d egid=d sgid=d fsgid=d tty=(none) ses=2 comm=brave exe=/usr/lib/brave-bin/brave key=brave_tor 
%

I was also running strace at the same time like this

strace -f -tt -s 1000 -p "$(pgrep -f /tor)" 2>&1|grep -C1000 SIGTERM|tee strace.log

so I have a strace log with a 1000 lines of context above and below the SIGTERM, I can provide that on request.

[wknapik]

Same/similar issue on Linux, macOS and Windows #8076.

[wknapik]

Interestingly, today, after the Tor process spawned by Brave was killed, closing the Tor window and opening a new one did work. A new Tor process was started and the new Tor window works, which is an improvement.

I'm now on an updated Brave version, compared to the original report:

% pacman -Q brave-bin 
brave-bin 1:1.3.114-1
% brave --version
Brave Browser 80.1.3.114 unknown
%

.	.
Brave	1.3.114 Chromium: 80.0.3987.87 (Official Build) unknown (64-bit)
Revision	449cb163497b70dbf98d389f54e38e85d4c59b43-refs/branch-heads/3987@{#801}
OS	Linux
JavaScript	V8 8.0.426.16
Flash	(Disabled)
User Agent	Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.87 Safari/537.36
Command Line	/usr/lib/brave-bin/brave --enable-dom-distiller --disable-domain-reliability --no-pings --extension-content-verification=enforce_strict --extensions-install-verification=enforce --sync-url=https://no-thanks.invalid --enable-features=PasswordImport,WebUIDarkMode,SimplifyHttpsIndicator --disable-features=AllowPopupsDuringPageUnload,NotificationTriggers,AutofillServerCommunication,WebXrGamepadModule,AudioServiceOutOfProcess,SmsReceiver,VideoPlaybackQuality,LookalikeUrlNavigationSuggestionsUI,WebXR --flag-switches-begin --enable-features=PasswordImport,WebUIDarkMode,SimplifyHttpsIndicator,WebRtcHideLocalIpsWithMdns --disable-features=AllowPopupsDuringPageUnload,NotificationTriggers,AutofillServerCommunication,WebXrGamepadModule,AudioServiceOutOfProcess,SmsReceiver,VideoPlaybackQuality,LookalikeUrlNavigationSuggestionsUI,WebXR,WebRTCPipeWireCapturer --flag-switches-end --disable-webrtc-apm-in-audio-service Executable Path /usr/lib/brave-bin/brave
Profile Path	/home/redacted/.config/BraveSoftware/Brave-Browser/Default

[wknapik]

Same/similar issue on macOS #6629

[wknapik]

I keep up-to-date with Brave releases and I haven't seen this happen in months.

[bsclifton]

@wknapik thanks for reporting back! I'll close this issue for now and if it happens again we can re-open. Happy new year! 😄