[tor-bugs] #17782 [Tor]: Relays may publish descriptors with incorrect IP address

Tor Bug Tracker & Wiki blackhole at torproject.org
Tue Jan 19 13:45:56 UTC 2016

#17782: Relays may publish descriptors with incorrect IP address
 Reporter:  fk            |          Owner:
     Type:  defect        |         Status:  new
 Priority:  High          |      Milestone:  Tor: 0.2.8.x-final
Component:  Tor           |        Version:  Tor: unspecified
 Severity:  Major         |     Resolution:
 Keywords:  027-backport  |  Actual Points:
Parent ID:  #17811        |         Points:
  Sponsor:                |

Comment (by teor):

 #17782 and #17765 may be caused by a race condition between address
 resolution and reachability self-testing:
 * tor discovers its correct address
 * tor initiates reachability tests to ORPort and DirPort on the correct
 * tor discovers an incorrect address
 * tor's reachability tests to the correct address succeed

 This means that we have to invalidate (forcibly close connections for)
 reachability tests when the address changes (if we don't already). This
 might be hard to do for OR connections, as connections from other servers
 to the correct address (from previous descriptors) still work, even if tor
 discovers the wrong address.

 However, after #18050, the DirPort self-test is also required before the
 descriptor is published, and this relies on having the correct address.
 This is only a partial solution, as not all relays have DirPorts.

 What we really need to do is check that we can make an OR connection to
 ourself (rather than receiving an OR connection from anywhere), or that we
 can make a Dir connection to ourself, or both if the OR and Dir addresses
 are different (#13953).

Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17782#comment:9>
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