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0d370a959b
Check for import errors with pylint to make sure new python package dependencies are not overlooked. https://fedorahosted.org/freeipa/ticket/6418 Reviewed-By: Petr Spacek <pspacek@redhat.com> Reviewed-By: Martin Basti <mbasti@redhat.com>
151 lines
4.5 KiB
Python
Executable File
151 lines
4.5 KiB
Python
Executable File
#!/usr/bin/python3
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#
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# Authors:
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# Christian Heimes <cheimes@redhat.com>
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; version 2 of the License.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License along
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# with this program; if not, write to the Free Software Foundation, Inc.,
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# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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#
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# Copyright (C) 2016 Red Hat, Inc.
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# All rights reserved.
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#
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"""Generate safe NSSCipherSuite stanza for mod_nss
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"""
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from __future__ import print_function
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import operator
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import re
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# pylint: disable=import-error,no-name-in-module
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from urllib.request import urlopen
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# pylint: enable=import-error,no-name-in-module
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SOURCE = "https://git.fedorahosted.org/cgit/mod_nss.git/plain/nss_engine_cipher.c"
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CIPHER_RE = re.compile(
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r'\s*\{'
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r'\"(?P<name>\w+)\",\s*'
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r'(?P<num>(TLS|SSL)_\w+),\s*'
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r'\"(?P<openssl_name>[\w-]+)\",\s*'
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r'(?P<attr>[\w|]+),\s*'
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r'(?P<version>\w+),\s*'
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r'(?P<strength>\w+),\s*'
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r'(?P<bits>\d+),\s*'
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r'(?P<alg_bits>\d+)'
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)
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DISABLED_CIPHERS = {
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# ciphers without encryption or authentication
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'SSL_eNULL', 'SSL_aNULL',
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# MD5 is broken
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# SHA-1 is still required as PRF algorithm for TLSv1.0
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'SSL_MD5',
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# RC2 and RC4 stream ciphers are broken.
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'SSL_RC2', 'SSL_RC4',
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# DES is broken and Triple DES is too weak.
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'SSL_DES', 'SSL_3DES',
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# DSA is problematic.
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'SSL_DSS', 'SSL_aDSS',
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# prefer AES over Camellia.
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'SSL_CAMELLIA128', 'SSL_CAMELLIA256', 'SSL_CAMELLIA',
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# non-ephemeral EC Diffie-Hellmann with fixed parameters are not
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# used by common browser and are therefore irrelevant for HTTPS.
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'kECDH', 'SSL_kECDHr', 'SSL_kECDHe'
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}
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WEAK_STRENGTH = {
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'SSL_STRONG_NONE',
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'SSL_EXPORT40',
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'SSL_EXPORT56',
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'SSL_LOW'
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}
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def parse_nss_engine_cipher(lines, encoding='utf-8'):
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"""Parse nss_engine_cipher.c and get list of ciphers
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:param lines: iterable or list of lines
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:param encoding: default encoding
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:return: list of cipher dicts
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"""
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ciphers = []
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start = False
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for line in lines:
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if not isinstance(line, str):
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line = line.decode(encoding)
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if line.startswith('cipher_properties'):
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start = True
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elif not start:
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continue
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elif line.startswith('};'):
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break
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mo = CIPHER_RE.match(line)
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if not mo:
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continue
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match = mo.groupdict()
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match['attr'] = set(match['attr'].split('|'))
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match['bits'] = int(match['bits'])
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match['alg_bits'] = int(match['alg_bits'])
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# some cipher elemets aren't flagged
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for algo in ['SHA256', 'SHA384']:
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if match['num'].endswith(algo):
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match['attr'].add('SSL_{}'.format(algo))
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# cipher block chaining isn't tracked
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if '_CBC' in match['num']:
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match['attr'].add('SSL_CBC')
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if match['attr'].intersection(DISABLED_CIPHERS):
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match['enabled'] = False
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elif match['strength'] in WEAK_STRENGTH:
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match['enabled'] = False
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else:
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match['enabled'] = True
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# EECDH + AES-CBC and large hash functions is slow and not more secure
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if (match['attr'].issuperset({'SSL_CBC', 'SSL_kEECDH'}) and
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match['attr'].intersection({'SSL_SHA256', 'SSL_SHA384'})):
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match['enabled'] = False
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ciphers.append(match)
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ciphers.sort(key=operator.itemgetter('name'))
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return ciphers
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def main():
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with urlopen(SOURCE) as r:
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ciphers = parse_nss_engine_cipher(r)
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# with open('nss_engine_cipher.c') as f:
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# ciphers = parse_nss_engine_cipher(f)
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print("# disabled cipher attributes: {}".format(
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', '.join(sorted(DISABLED_CIPHERS))))
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print("# weak strength: {}".format(', '.join(sorted(WEAK_STRENGTH))))
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print("# enabled cipher suites:")
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suite = []
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for cipher in ciphers:
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if cipher['enabled']:
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print("# {:36}".format(cipher['num']))
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suite.append('+{}'.format(cipher['name']))
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print()
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print("NSSCipherSuite {}".format(','.join(suite)))
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if __name__ == '__main__':
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main()
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