[tor-bugs] #13111 [Tor]: Tor fails to start if onion keys are zero length

[Tor Bug Tracker & Wiki]

#13111: Tor fails to start if onion keys are zero length
---------------------+---------------------
 Reporter:  ioerror  |          Owner:
     Type:  defect   |         Status:  new
 Priority:  normal   |      Milestone:
Component:  Tor      |        Version:
 Keywords:           |  Actual Points:
Parent ID:           |         Points:
---------------------+---------------------
 I'm using a very unstable embedded device to run a transparent Tor
 router/relay/hidden service. In some cases - the device will reset the
 clock to 1970 (hooray, no RTC!) or the clock will be otherwise incorrect
 (hooray, low battery on the RTC!). Furthermore, the device will sometimes
 be unplugged at random (solar panel dies, janitor unplugs it, etc) and
 this results in a state/keys directory that looks like as follows:
 {{{
 Sep 10 13:31:48.000 [notice] Tor 0.2.4.23 (git-417f0cacd726e549) opening
 log file.
 Sep 10 13:31:48.000 [notice] Not disabling debugger attaching for
 unprivileged users.
 Sep 10 13:31:48.000 [notice] Parsing GEOIP IPv4 file /usr/share/tor/geoip.
 Sep 10 13:31:48.000 [notice] Parsing GEOIP IPv6 file
 /usr/share/tor/geoip6.
 Sep 10 13:31:49.000 [notice] Configured to measure statistics. Look for
 the *-stats files that will first be written to the data directory in 24
 hours from now.
 Sep 10 13:31:49.000 [warn] crypto error while Error parsing private key:
 no start line (in PEM routines:PEM_read_bio)
 Sep 10 13:31:49.000 [err] Error loading private key.
 Sep 10 13:31:49.000 [err] do_main_loop(): Bug: Error initializing keys;
 exiting
 }}}

 {{{
 root at debian:/var/lib/tor/keys# ls -al
 total 20
 drwx--S--- 2 debian-tor debian-tor 4096 Aug 15 14:56 .
 drwx--S--- 5 debian-tor debian-tor 4096 Sep 10 13:31 ..
 -rw------- 1 debian-tor debian-tor  887 Sep 10 13:30 secret_id_key
 -rw------- 1 debian-tor debian-tor    0 Sep 10 13:30 secret_onion_key
 -rw------- 1 debian-tor debian-tor  891 Sep 10 13:30 secret_onion_key.old
 -rw------- 1 debian-tor debian-tor    0 Sep 10 13:30 secret_onion_key_ntor
 -rw------- 1 debian-tor debian-tor   96 Sep 10 13:30
 secret_onion_key_ntor.old
 }}}

 If I remove the zero byte files and restart Tor, all is well:
 {{{
 root at debian:/var/lib/tor/keys# rm secret_onion_key*
 /etc/init.d/tor restart
 }}}

 I think that Tor should notice that the files are zero bytes in length and
 gracefully generate the keys.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13111>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online