exclude_badExits/trustor_poc.py

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2022-11-07 11:38:22 +00:00
# -*- mode: python; indent-tabs-mode: nil; py-indent-offset: 4; coding: utf-8 -# -*- coding: utf-8 -*-
import os
import sys
from stem.control import Controller
from stem.util.tor_tools import *
from urllib.parse import urlparse
import requests
import datetime
try:
from unbound import ub_ctx,RR_TYPE_TXT,RR_CLASS_IN
except:
ub_ctx = RR_TYPE_TXT = RR_CLASS_IN = None
global LOG
import logging
LOG = logging.getLogger()
# download this python library from
# https://github.com/erans/torcontactinfoparser
#sys.path.append('/home/....')
try:
from torcontactinfo import TorContactInfoParser
except:
TorContactInfoParser = None
# tor ControlPort IP
controller_address = '127.0.0.1'
dnssec_DS_file = 'dnssec-root-trust'
# this is not the system wide /etc/resolv.conf
# use dnscrypt-proxy to encrypt your DNS and route it via tor's SOCKSPort
libunbound_resolv_file = 'resolv.conf'
# for now we support max_depth = 0 only
# this PoC version has no support for recursion
# https://github.com/nusenu/tor-relay-operator-ids-trust-information#trust-information-consumers
supported_max_depths = ['0']
# https://github.com/nusenu/ContactInfo-Information-Sharing-Specification#ciissversion
accepted_ciissversions = ['2']
# https://github.com/nusenu/ContactInfo-Information-Sharing-Specification#proof
accepted_proof_types = ['uri-rsa','dns-rsa']
# https://stackoverflow.com/questions/2532053/validate-a-hostname-string
# FIXME this check allows non-fqdn names
def is_valid_hostname(hostname):
if len(hostname) > 255:
return False
if hostname[-1] == ".":
hostname = hostname[:-1] # strip exactly one dot from the right, if present
allowed = re.compile("(?!-)[A-Z\d-]{1,63}(?<!-)$", re.IGNORECASE)
return all(allowed.match(x) for x in hostname.split("."))
def read_local_trust_config(trust_config='trust_config'):
'''
reads a local configuration file containing trusted domains
and returns them in an array
'''
result = []
if (os.path.isfile(trust_config)):
f = open(trust_config)
for line in f:
line = line.strip()
if line[0] == '#':
continue
try:
domain, max_depth = line.split(':')
except:
LOG.error('invalid trust config line detected: %s aborting!' % line)
sys.exit(8)
if max_depth in supported_max_depths:
if is_valid_hostname(domain) and domain not in result:
result.append(domain)
else:
LOG.error('invalid duplicate domain in trust config file: %s: %s aborting!' % (trust_config, domain))
sys.exit(9)
else:
LOG.error('unsupported max_depth value (%s) used, aborting!' % line)
sys.exit(10)
return result
else:
LOG.error("trust config file %s missing, aborting!" % trust_config)
sys.exit(11)
def read_local_validation_cache(validation_cache_file, trusted_domains=[]):
'''
reads the local validation cache and returns all fingerprints in the cache
for trusted domains
format of each entry in the cache:
domain:fingerprint:prooftype:date
'''
result = []
if trusted_domains == []:
return result
if (os.path.isfile(validation_cache_file)):
f = open(validation_cache_file)
for line in f:
line = line.strip()
if line[0] == '#':
continue
try:
domain, fingerprint, prooftype, dt = line.split(':')
except:
LOG.error('invalid trust cache entry detected: %s aborting!' % line)
sys.exit(12)
if domain in trusted_domains:
result.append(fingerprint)
else:
print('ignoring cached entry for untrusted domain %s' % domain)
else:
print("Validation cache file not present. It will be created.")
return result
def get_controller(address='127.0.0.1',port=9151,password=''):
'''
connects to a local tor client via the tor ControlPort
and returns a controller that allows us to easily set specific tor
configuration options or read tor relay ContactInfo strings for validation
'''
try:
#controller = Controller.from_socket_file(path=torsocketpath)
controller = Controller.from_port(address=address, port=port)
controller.authenticate(password=password)
except Exception as e:
LOG.error(f'Failed to connect to the tor process, {e}')
sys.exit(1)
if not controller.is_set('UseMicrodescriptors'):
LOG.error('"UseMicrodescriptors 0" is required in your torrc configuration. Exiting.')
sys.exit(2)
return controller
def find_validation_candidates(controller, trusted_domains=[],validation_cache=[],accept_all=False):
'''
connect to a tor client via controlport and return a dict of all
not yet validated fingerprints per trusted operators
format:
{ trusted_domain: { prooftype: [fingerprint, fingerprint, ...]} }
example content:
{ 'emeraldonion.org' : { 'uri-rsa': ['044600FD968728A6F220D5347AD897F421B757C0', '09DCA3360179C6C8A5A20DDDE1C54662965EF1BA']}}
'''
result = {}
try:
relays = controller.get_server_descriptors()
except:
LOG.error('Failed to get relay descriptors via tor\'s ControlPort. Exiting.')
sys.exit(3)
ci = TorContactInfoParser()
for relay in relays:
if relay.contact:
fingerprint = relay.fingerprint
# skip fingerprints we have already successfully validated in the past
# a future version would check the cache age as well
if fingerprint in validation_cache:
continue
contactstring = relay.contact.decode('utf-8')
parsed_ci = ci.parse(contactstring)
if len(parsed_ci) > 0:
if 'ciissversion' in parsed_ci and 'proof' in parsed_ci and 'url' in parsed_ci:
prooftype = parsed_ci['proof']
ciurl = parsed_ci['url']
if parsed_ci['ciissversion'] in accepted_ciissversions and prooftype in accepted_proof_types:
if ciurl.startswith('http://') or ciurl.startswith('https://'):
try:
domain=urlparse(ciurl).netloc
except:
LOG.warning('failed to parse domain %s' % ciurl)
domain='error'
continue
else:
domain=ciurl
if not is_valid_hostname(domain):
domain='error'
continue
# we can ignore relays that do not claim to be operated by a trusted operator
# if we do not accept all
if domain not in trusted_domains and not accept_all:
continue
if domain in result.keys():
if prooftype in result[domain].keys():
result[domain][prooftype].append(fingerprint)
else:
result[domain] = { prooftype : [fingerprint] }
# mixed proof types are not allowd as per spec but we are not strict here
LOG.warning('%s is using mixed prooftypes %s' % (domain, prooftype))
else:
result[domain] = {prooftype : [fingerprint]}
return result
def lDownloadUrlFps(domain, timeout=20, host='127.0.0.1', port=9050):
uri="https://"+domain+"/.well-known/tor-relay/rsa-fingerprint.txt"
# socks proxy used for outbound web requests (for validation of proofs)
proxy = {'https': 'socks5h://' +host +':' +str(port)}
# we use this UA string when connecting to webservers to fetch rsa-fingerprint.txt proof files
# https://nusenu.github.io/ContactInfo-Information-Sharing-Specification/#uri-rsa
headers = {'User-Agent':'Mozilla/5.0 (Windows NT 10.0; rv:91.0) Gecko/20100101 Firefox/91.0'}
LOG.debug("fetching %s...." % uri)
try:
head = requests.head(uri, timeout=timeout, proxies=proxy, headers=headers)
except Exception as e:
print("HTTP HEAD request failed for %s" % uri)
print(e)
head = None
return []
if head.status_code != 200:
return []
if not head.headers['Content-Type'].startswith('text/plain'):
return []
try:
fullfile = requests.get(uri, proxies=proxy, timeout=10, headers=headers)
except:
print("HTTP GET request failed for %s" % uri)
return []
if fullfile.status_code != 200 or not fullfile.headers['Content-Type'].startswith('text/plain'):
return []
#check for redirects (not allowed as per spec)
if fullfile.url != uri:
LOG.error('Redirect detected %s vs %s (final)' % (uri, fullfile.url))
return []
well_known_content = [i.strip() for i in fullfile.text.upper().split('\n')]
return well_known_content
def validate_proofs(candidates, validation_cache_file):
'''
This function takes the return value of find_validation_candidates()
and validated them according to their proof type (uri-rsa, dns-rsa)
and writes properly validated relay fingerprints to the local validation cache
'''
dt_utc = datetime.datetime.now(datetime.timezone.utc).date()
f = open(validation_cache_file, mode='a')
count = 0
for domain in candidates.keys():
for prooftype in candidates[domain].keys():
if prooftype == 'uri-rsa':
well_known_content = lDownloadUrlFps(domain, timeout=20, host='127.0.0.1', port=9050)
for fingerprint in candidates[domain][prooftype]:
if fingerprint in well_known_content:
# write cache entry
count += 1
f.write('%s:%s:%s:%s\n' % (domain, fingerprint, prooftype, dt_utc))
else:
LOG.error('%s:%s:%s' % (fingerprint, domain, prooftype))
elif prooftype == 'dns-rsa' and ub_ctx:
for fingerprint in candidates[domain][prooftype]:
fp_domain = fingerprint+'.'+domain
if dns_validate(fp_domain):
count += 1
f.write('%s:%s:%s:%s\n' % (domain, fingerprint, prooftype, dt_utc))
else:
LOG.error('%s:%s:%s' % (fingerprint, domain, prooftype))
f.close()
LOG.info('successfully validated %s new (not yet validated before) relays' % count)
def dns_validate(domain):
'''
performs DNS TXT lookups and verifies the reply
- is DNSSEC valid and
- contains only a single TXT record
- the DNS record contains a hardcoded string as per specification
https://nusenu.github.io/ContactInfo-Information-Sharing-Specification/#dns-rsa
'''
if not ub_ctx: return False
ctx = ub_ctx()
if (os.path.isfile(libunbound_resolv_file)):
ctx.resolvconf(libunbound_resolv_file)
else:
LOG.error('libunbound resolv config file: "%s" is missing, aborting!' % libunbound_resolv_file)
sys.exit(5)
if (os.path.isfile(dnssec_DS_file)):
ctx.add_ta_file(dnssec_DS_file)
else:
LOG.error('DNSSEC trust anchor file "%s" is missing, aborting!' % dnssec_DS_file)
sys.exit(6)
status, result = ctx.resolve(domain, RR_TYPE_TXT, RR_CLASS_IN)
if status == 0 and result.havedata:
if len(result.rawdata) == 1 and result.secure:
# ignore the first byte, it is the TXT length
if result.data.as_raw_data()[0][1:] == b'we-run-this-tor-relay':
return True
return False
def configure_tor(controller, trusted_fingerprints, exitonly=True):
'''
takes the list of trusted fingerprints and configures a tor client
to only use trusted relays in a certain position
for now we only set exits.
we refuse to set the configuration if there are less then 40 trusted relays
'''
relay_count = len(trusted_fingerprints)
if relay_count < 41:
print('Too few trusted relays (%s), aborting!' % relay_count)
sys.exit(15)
try:
controller.set_conf('ExitNodes', trusted_fingerprints)
print('limited exits to %s relays' % relay_count)
except Exception as e:
print('Failed to set ExitNodes tor config to trusted relays')
print(e)
sys.exit(20)
if __name__ == '__main__':
trust_config = 'trust_config'
assert os.path.exists(trust_config)
trusted_domains = read_local_trust_config(trust_config)
validation_cache_file = 'validation_cache'
trusted_fingerprints = read_local_validation_cache(validation_cache_file,
trusted_domains=trusted_domains)
# tor ControlPort password
controller_password=''
controller = get_controller(address=controller_address,password=controller_password)
r = find_validation_candidates(controller,validation_cache=trusted_fingerprints,trusted_domains=trusted_domains)
validate_proofs(r, validation_cache_file)
# refresh list with newly validated fingerprints
trusted_fingerprints = read_local_validation_cache(trusted_domains=trusted_domains)
configure_tor(controller, trusted_fingerprints)