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Merge remote-tracking branch 'public/bug11513_024'

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This commit is contained in:
Nick Mathewson 2014-04-15 14:54:25 -04:00
commit 2704441e7f
3 changed files with 155 additions and 12 deletions
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12
changes/bug11513 Normal file
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@ -0,0 +1,12 @@
o Major bugfixes:
- Generate the server's preference list for ciphersuites
automatically based on uniform criteria, and considering all
OpenSSL ciphersuites with acceptable strength and forward
secrecy. (The sort order is: prefer AES to 3DES; break ties by
preferring ECDHE to DHE; break ties by preferring GCM to CBC;
break ties by preferring SHA384 to SHA256 to SHA1; and finally,
break ties by preferring AES256 to AES128.) This resolves bugs
#11513, #11492, #11498, #11499. Bugs reported by 'cypherpunks'.
Bugfix on 0.2.4.8-alpha.

115
src/common/gen_server_ciphers.py Executable file
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@ -0,0 +1,115 @@
#!/usr/bin/python
# Copyright 2014, The Tor Project, Inc
# See LICENSE for licensing information
# This script parses openssl headers to find ciphersuite names, determines
# which ones we should be willing to use as a server, and sorts them according
# to preference rules.
#
# Run it on all the files in your openssl include directory.
import re
import sys
EPHEMERAL_INDICATORS = [ "_EDH_", "_DHE_", "_ECDHE_" ]
BAD_STUFF = [ "_DES_40_", "MD5", "_RC4_", "_DES_64_",
"_SEED_", "_CAMELLIA_", "_NULL" ]
# these never get #ifdeffed.
MANDATORY = [
"TLS1_TXT_DHE_RSA_WITH_AES_256_SHA",
"TLS1_TXT_DHE_RSA_WITH_AES_128_SHA",
"SSL3_TXT_EDH_RSA_DES_192_CBC3_SHA",
]
def find_ciphers(filename):
with open(filename) as f:
for line in f:
m = re.search(r'(?:SSL3|TLS1)_TXT_\w+', line)
if m:
yield m.group(0)
def usable_cipher(ciph):
ephemeral = False
for e in EPHEMERAL_INDICATORS:
if e in ciph:
ephemeral = True
if not ephemeral:
return False
if "_RSA_" not in ciph:
return False
for b in BAD_STUFF:
if b in ciph:
return False
return True
# All fields we sort on, in order of priority.
FIELDS = [ 'cipher', 'fwsec', 'mode', 'digest', 'bitlength' ]
# Map from sorted fields to recognized value in descending order of goodness
FIELD_VALS = { 'cipher' : [ 'AES', 'DES'],
'fwsec' : [ 'ECDHE', 'DHE' ],
'mode' : [ 'GCM', 'CBC' ],
'digest' : [ 'SHA384', 'SHA256', 'SHA' ],
'bitlength' : [ '256', '128', '192' ],
}
class Ciphersuite(object):
def __init__(self, name, fwsec, cipher, bitlength, mode, digest):
self.name = name
self.fwsec = fwsec
self.cipher = cipher
self.bitlength = bitlength
self.mode = mode
self.digest = digest
for f in FIELDS:
assert(getattr(self, f) in FIELD_VALS[f])
def sort_key(self):
return tuple(FIELD_VALS[f].index(getattr(self,f)) for f in FIELDS)
def parse_cipher(ciph):
m = re.match('(?:TLS1|SSL3)_TXT_(EDH|DHE|ECDHE)_RSA(?:_WITH)?_(AES|DES)_(256|128|192)(|_CBC|_CBC3|_GCM)_(SHA|SHA256|SHA384)$', ciph)
if not m:
print "/* Couldn't parse %s ! */"%ciph
return None
fwsec, cipher, bits, mode, digest = m.groups()
if fwsec == 'EDH':
fwsec = 'DHE'
if mode in [ '_CBC3', '_CBC', '' ]:
mode = 'CBC'
elif mode == '_GCM':
mode = 'GCM'
return Ciphersuite(ciph, fwsec, cipher, bits, mode, digest)
ALL_CIPHERS = []
for fname in sys.argv[1:]:
ALL_CIPHERS += (parse_cipher(c)
for c in find_ciphers(fname)
if usable_cipher(c) )
ALL_CIPHERS.sort(key=Ciphersuite.sort_key)
for c in ALL_CIPHERS:
if c is ALL_CIPHERS[-1]:
colon = ';'
else:
colon = ' ":"'
if c.name in MANDATORY:
print " /* Required */"
print ' %s%s'%(c.name,colon)
else:
print "#ifdef %s"%c.name
print ' %s%s'%(c.name,colon)
print "#endif"

40
src/common/tortls.c
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@ -712,31 +712,47 @@ tor_tls_create_certificate(crypto_pk_t *rsa,
/** List of ciphers that servers should select from when we actually have
* our choice of what cipher to use. */
const char UNRESTRICTED_SERVER_CIPHER_LIST[] =
#ifdef TLS1_TXT_ECDHE_RSA_WITH_AES_256_CHC_SHA
TLS1_TXT_ECDHE_RSA_WITH_AES_256_CBC_SHA ":"
#endif
/* This list is autogenerated with the gen_server_ciphers.py script;
* don't hand-edit it. */
#ifdef TLS1_TXT_ECDHE_RSA_WITH_AES_256_GCM_SHA384
TLS1_TXT_ECDHE_RSA_WITH_AES_256_GCM_SHA384 ":"
#endif
#ifdef TLS1_TXT_ECDHE_RSA_WITH_AES_128_GCM_SHA256
TLS1_TXT_ECDHE_RSA_WITH_AES_128_GCM_SHA256 ":"
#endif
#ifdef TLS1_TXT_ECDHE_RSA_WITH_AES_256_SHA384
TLS1_TXT_ECDHE_RSA_WITH_AES_256_SHA384 ":"
#endif
#ifdef TLS1_TXT_ECDHE_RSA_WITH_AES_128_SHA256
TLS1_TXT_ECDHE_RSA_WITH_AES_128_SHA256 ":"
#endif
#ifdef TLS1_TXT_ECDHE_RSA_WITH_AES_256_CBC_SHA
TLS1_TXT_ECDHE_RSA_WITH_AES_256_CBC_SHA ":"
#endif
#ifdef TLS1_TXT_ECDHE_RSA_WITH_AES_128_CBC_SHA
TLS1_TXT_ECDHE_RSA_WITH_AES_128_CBC_SHA ":"
#endif
#ifdef TLS1_TXT_ECDHE_RSA_WITH_AES_128_GCM_SHA256
TLS1_TXT_ECDHE_RSA_WITH_AES_128_GCM_SHA256
#ifdef TLS1_TXT_DHE_RSA_WITH_AES_256_GCM_SHA384
TLS1_TXT_DHE_RSA_WITH_AES_256_GCM_SHA384 ":"
#endif
//#if TLS1_TXT_ECDHE_RSA_WITH_RC4_128_SHA
// TLS1_TXT_ECDHE_RSA_WITH_RC4_128_SHA ":"
//#endif
/* These next two are mandatory. */
TLS1_TXT_DHE_RSA_WITH_AES_256_SHA ":"
TLS1_TXT_DHE_RSA_WITH_AES_128_SHA ":"
#ifdef TLS1_TXT_DHE_RSA_WITH_AES_128_GCM_SHA256
TLS1_TXT_DHE_RSA_WITH_AES_128_GCM_SHA256 ":"
#endif
#ifdef TLS1_TXT_DHE_RSA_WITH_AES_256_SHA256
TLS1_TXT_DHE_RSA_WITH_AES_256_SHA256 ":"
#endif
#ifdef TLS1_TXT_DHE_RSA_WITH_AES_128_SHA256
TLS1_TXT_DHE_RSA_WITH_AES_128_SHA256 ":"
#endif
/* Required */
TLS1_TXT_DHE_RSA_WITH_AES_256_SHA ":"
/* Required */
TLS1_TXT_DHE_RSA_WITH_AES_128_SHA ":"
#ifdef TLS1_TXT_ECDHE_RSA_WITH_DES_192_CBC3_SHA
TLS1_TXT_ECDHE_RSA_WITH_DES_192_CBC3_SHA ":"
#endif
SSL3_TXT_EDH_RSA_DES_192_CBC3_SHA;
/* Required */
SSL3_TXT_EDH_RSA_DES_192_CBC3_SHA;
/* Note: to set up your own private testing network with link crypto
* disabled, set your Tors' cipher list to