Bug 665698 – net-vpn/tor-0.3.4.7_rc sandbox not working anymore

• Product: Gentoo Linux
• Status: RESOLVED OBSOLETE

[Description Hadrien Lacour 2018-09-11 10:25:32 UTC]

Hello, since the update to 0.3.4.7_rc, if I have Sandbox 1 in my /etc/torrc, I get these

Sep 11 12:20:58 gentoo Tor[8103]: Could not open "/var/lib/tor/data/cached-certs": Permission denied
Sep 11 12:20:58 gentoo Tor[8103]: Could not open "/var/lib/tor/data/cached-consensus": Permission denied
Sep 11 12:20:58 gentoo Tor[8103]: Could not open "/var/lib/tor/data/unverified-consensus": Permission denied
Sep 11 12:20:58 gentoo Tor[8103]: Could not open "/var/lib/tor/data/cached-microdesc-consensus": Permission denied
Sep 11 12:20:58 gentoo Tor[8103]: Could not open "/var/lib/tor/data/unverified-microdesc-consensus": Permission denied
Sep 11 12:20:58 gentoo Tor[8103]: Could not open "/var/lib/tor/data/cached-microdescs" for mmap(): Permission denied
Sep 11 12:20:58 gentoo Tor[8103]: Could not open "/var/lib/tor/data/cached-microdescs.new": Permission denied
Sep 11 12:20:58 gentoo Tor[8103]: Could not open "/var/lib/tor/data/cached-descriptors" for mmap(): Permission denied
Sep 11 12:20:58 gentoo Tor[8103]: Could not open "/var/lib/tor/data/cached-extrainfo" for mmap(): Permission denied

in syslog, and the service crashes. Here's the whole torrc, for reference:

#
# Minimal torrc so tor will work out of the box
#
User tor
Log notice syslog
DataDirectory /var/lib/tor/data

UseEntryGuards 0
SafeLogging 1
Sandbox 1

[Comment 1 Kai Damm 2018-09-11 12:05:06 UTC]

Tor 0.3.1 and 0.3.3 (removed from tree today) work fine. The bad syscall in 0.3.4 is openat:

With a user ~/.torrc:
RunAsDaemon 0
Sandbox 1

and
tor -f ~/.torrc

The following output results:

Sep 11 13:49:26.854 [notice] Tor 0.3.4.7-rc (git-8465a8d84647c349) running on Linux with Libevent 2.1.8-stable, OpenSSL 1.0.2p, Zlib 1.2.11, Liblzma 5.2.3, and Libzstd N/A.
Sep 11 13:49:26.854 [notice] Tor can't help you if you use it wrong! Learn how to be safe at https://www.torproject.org/download/download#warning
Sep 11 13:49:26.854 [notice] Read configuration file "/home/kai/.torrc".
Sep 11 13:49:26.859 [notice] Scheduler type KIST has been enabled.
Sep 11 13:49:26.859 [notice] Opening Socks listener on 127.0.0.1:9050
Sep 11 13:49:26.000 [notice] Parsing GEOIP IPv4 file /usr/share/tor/geoip.
Sep 11 13:49:27.000 [notice] Parsing GEOIP IPv6 file /usr/share/tor/geoip6.
Sep 11 13:49:27.000 [notice] Bootstrapped 0%: Starting
Sep 11 13:49:27.000 [warn] Could not open "/home/kai/.tor/cached-certs": Permission denied
Sep 11 13:49:27.000 [warn] Could not open "/home/kai/.tor/cached-consensus": Permission denied
Sep 11 13:49:27.000 [warn] Could not open "/home/kai/.tor/unverified-consensus": Permission denied
Sep 11 13:49:27.000 [warn] Could not open "/home/kai/.tor/cached-microdesc-consensus": Permission denied
Sep 11 13:49:27.000 [warn] Could not open "/home/kai/.tor/unverified-microdesc-consensus": Permission denied
Sep 11 13:49:27.000 [warn] Could not open "/home/kai/.tor/cached-microdescs" for mmap(): Permission denied
Sep 11 13:49:27.000 [warn] Could not open "/home/kai/.tor/cached-microdescs.new": Permission denied
Sep 11 13:49:27.000 [warn] Could not open "/home/kai/.tor/cached-descriptors" for mmap(): Permission denied
Sep 11 13:49:27.000 [warn] Could not open "/home/kai/.tor/cached-extrainfo" for mmap(): Permission denied
Sep 11 13:49:27.000 [notice] Starting with guard context "default"

============================================================ T= 1536666568
(Sandbox) Caught a bad syscall attempt (syscall openat)
tor(+0x2082ab)[0x5555e52ac2ab]
/lib64/libpthread.so.0(open64+0x5d)[0x7f3a603923cd]
/lib64/libpthread.so.0(open64+0x5d)[0x7f3a603923cd]
tor(tor_open_cloexec+0x5a)[0x5555e528bcfa]
tor(start_writing_to_file+0x1fc)[0x5555e52a4f2c]
tor(+0x20106b)[0x5555e52a506b]
tor(+0x201242)[0x5555e52a5242]
tor(or_state_save+0x229)[0x5555e518e6d9]
tor(+0x603ea)[0x5555e51043ea]
tor(+0x85aa4)[0x5555e5129aa4]
/usr/lib64/libevent-2.1.so.6(+0x29253)[0x7f3a61199253]
/usr/lib64/libevent-2.1.so.6(event_base_loop+0x52f)[0x7f3a6119a33f]
tor(do_main_loop+0x2cc)[0x5555e5109c8c]
tor(tor_run_main+0x20d5)[0x5555e510d9d5]
tor(tor_main+0x47)[0x5555e5102077]
tor(main+0x26)[0x5555e5101d86]
/lib64/libc.so.6(__libc_start_main+0xfd)[0x7f3a5ffd005d]
tor(_start+0x2a)[0x5555e5101dea]

[Comment 2 Kai Damm 2018-09-13 15:31:06 UTC]

Upstream bug: https://trac.torproject.org/projects/tor/ticket/25440

But the commit is already in the source code:
https://github.com/Jigsaw52/tor/commit/ed06866e8145b9cfb47acb5fc185e6de01d90a49

And reverting that change in sandbox.c makes tor work again with Sandbox=1. Same with tor-0.3.4.8.

[Comment 3 Kai Damm 2018-09-14 11:59:38 UTC]

Finally found the actual upstream ticket:
https://trac.torproject.org/projects/tor/ticket/27315

[Comment 4 Kai Damm 2018-09-14 11:59:47 UTC]

Created attachment 546906 [details, diff]
patch fixing sandbox openat regression from 0.3.4.7_rc

[Comment 5 Anthony Basile 2018-10-26 14:18:34 UTC]

(In reply to Kai Damm from comment #4)
> Created attachment 546906 [details, diff] [details, diff]
> patch fixing sandbox openat regression from 0.3.4.7_rc

looking at the upstream bug, it seems that it didn't land for 0.3.4.8.  if its not in 0.3.4.9 when it comes out, i'll backport.

[Comment 6 Kai Damm 2018-11-07 11:31:15 UTC]

The patch is not in the code for 0.3.4.9, but tor still works with sandbox, without patch. Even 0.3.4.7 works if compiled again. Possibly glibc related? The update to glibc-2.27 has been in between.

[Comment 7 Anthony Basile 2019-02-03 00:43:03 UTC]

(In reply to Kai Damm from comment #6)
> The patch is not in the code for 0.3.4.9, but tor still works with sandbox,
> without patch. Even 0.3.4.7 works if compiled again. Possibly glibc related?
> The update to glibc-2.27 has been in between.

weird.