[tor-bugs] #20989 [Applications/Tor Browser]: browser sandbox profile too restrictive on OSX 10.12.2

Tor Bug Tracker & Wiki blackhole at torproject.org
Mon Dec 19 16:08:03 UTC 2016


#20989: browser sandbox profile too restrictive on OSX 10.12.2
-------------------------------------------------+-------------------------
 Reporter:  mcs                                  |          Owner:  mcs
     Type:  defect                               |         Status:
                                                 |  needs_information
 Priority:  Medium                               |      Milestone:
Component:  Applications/Tor Browser             |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tbb-security, tbb-sandboxing,        |  Actual Points:
  TorBrowserTeam201612                           |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
-------------------------------------------------+-------------------------

Comment (by mcs):

 Replying to [comment:3 mactoruser]:
 > There are no 3d party system extensions, I use the 2016 Macbook Pro 15'
 (with the Touch Bar)
 > so that is what com.apple.inputmethod.EmojiFunctionRowItem is.
 > Not sure about
 file://localhost/Library/Preferences/com.apple.ViewBridge.plist but why
 Tor Browser needs it anyway?

 It is difficult to know, but it may be related to the Touch Bar.

 > I hope there is a way to make this input method blocked in TorBrowser,
 since the way I see it it's just another potential fingerprinting issue of
 users with Touch Bar.

 It is unclear whether webpages can tell that the Touch Bar is available,
 but if they can there may be a fingerprinting issue.

 > The Tor Browser window opens but Tor button is red, like when the Tor
 Daemon is down.
 > Nothing loads obviosuly.
 >
 > Maybe this can help?
 >
 https://webkit.googlesource.com/WebKit/+/master/Source/WebKit2/Resources/PlugInSandboxProfiles/com.apple.WebKit
 .plugin-common.sb
 >
 > Chromium has this plist in this array:
 > ;; Open and Save panels
 > (define (webkit-powerbox)
 >     (allow file-read* (literal
 "/Library/Preferences/com.apple.ViewBridge.plist"))
 > ...

 Thanks! Are you willing to do some experiments for us? First, remove the
 following lines from tb.sb (otherwise, a new browser profile is created
 each time, which is not good):
 {{{
  ; Disallow writes to the profiles ini file.
  (deny file-write*
        (torbrowser-data-dir-subpath "/Browser/profiles.ini")
  )
 }}}

 Then remove your TorBrowser-Data/Browser directory to delete any extra
 profiles.

 Next, see what happens if you add the following line to tb.sb:
  (allow file-read* (literal
 "/Library/Preferences/com.apple.ViewBridge.plist"))

 If you still cannot visit any websites using the browser, edit your
 prefs.js file (TorBrowser-Data/Browser/*.default/prefs.js) and add the
 following lines:
 {{{
 user_pref("extensions.torbutton.loglevel", 0);
 user_pref("extensions.torbutton.logmethod", 0);
 user_pref("extensions.torlauncher.loglevel", 0);
 user_pref("extensions.torlauncher.logmethod", 0);
 }}}

 Then share the `./start-tor-with-sandbox` and `./start-browser-with-
 sandbox` output with us.

 One final thing to do is to open the macOS Console application and look
 for messages that contain `SandboxViolation`.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20989#comment:4>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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