[tor-bugs] #25400 [Core Tor/Tor]: CIRC_BW event miscounts, should count all circ data

Tor Bug Tracker & Wiki blackhole at torproject.org
Fri Mar 2 04:51:29 UTC 2018

#25400: CIRC_BW event miscounts, should count all circ data
 Reporter:  mikeperry     |          Owner:  mikeperry
     Type:  defect        |         Status:  needs_review
 Priority:  Medium        |      Milestone:  Tor: 0.3.4.x-final
Component:  Core Tor/Tor  |        Version:
 Severity:  Normal        |     Resolution:
 Keywords:  tor-stats     |  Actual Points:
Parent ID:                |         Points:
 Reviewer:                |        Sponsor:
Changes (by mikeperry):

 * status:  assigned => needs_review


 Patch in mikeperry/bug25400. Spec patch in my torspec remote, also branch

 Right now this branch only counts relay cells, which is similar to the
 behavior before. I decided against counting CREATED cells, and VAR cells,
 because those are a bit weird since there is not a circuit ID on the
 outgoing cell, only upon the response. Let me know what you think.

 For what it's worth, counting all cells (including
 padding/dropped/rejected/partially full ones) in circuit bandwidth totals
 allows a Tor controller to check for side channel attacks by doing
 accounting on STREAM_BW totals on a circuit and comparing that to the
 CIRC_BW totals. Large differences indicate side channel abuse (depending
 on the application protocol).

Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25400#comment:2>
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