The list of supported TLS cipher suites in /etc/httpd/conf.d/nss.conf has been modernized. Insecure or less secure algorithms such as RC4, DES and 3DES are removed. Perfect forward secrecy suites with ephemeral ECDH key exchange have been added. IE 8 on Windows XP is no longer supported.
The list of enabled cipher suites has been generated with the script contrib/nssciphersuite/nssciphersuite.py. The supported suites are currently: TLS_RSA_WITH_AES_128_CBC_SHA256 TLS_RSA_WITH_AES_256_CBC_SHA256 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA TLS_RSA_WITH_AES_128_GCM_SHA256 TLS_RSA_WITH_AES_128_CBC_SHA TLS_RSA_WITH_AES_256_GCM_SHA384 TLS_RSA_WITH_AES_256_CBC_SHA https://fedorahosted.org/freeipa/ticket/5589
From 26d356970ef1f7de7b00fe237f67345c507c7989 Mon Sep 17 00:00:00 2001 From: Christian Heimes <chei...@redhat.com> Date: Thu, 21 Jan 2016 16:09:10 +0100 Subject: [PATCH] Modernize mod_nss's cipher suites The list of supported TLS cipher suites in /etc/httpd/conf.d/nss.conf has been modernized. Insecure or less secure algorithms such as RC4, DES and 3DES are removed. Perfect forward secrecy suites with ephemeral ECDH key exchange have been added. IE 8 on Windows XP is no longer supported. The list of enabled cipher suites has been generated with the script contrib/nssciphersuite/nssciphersuite.py. The supported suites are currently: TLS_RSA_WITH_AES_128_CBC_SHA256 TLS_RSA_WITH_AES_256_CBC_SHA256 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA TLS_RSA_WITH_AES_128_GCM_SHA256 TLS_RSA_WITH_AES_128_CBC_SHA TLS_RSA_WITH_AES_256_GCM_SHA384 TLS_RSA_WITH_AES_256_CBC_SHA https://fedorahosted.org/freeipa/ticket/5589 Signed-off-by: Christian Heimes <chei...@redhat.com> --- contrib/nssciphersuite/README.txt | 38 ++++++++ contrib/nssciphersuite/nssciphersuite.py | 147 +++++++++++++++++++++++++++++++ ipaserver/install/httpinstance.py | 18 ++++ ipaserver/install/server/upgrade.py | 14 +++ 4 files changed, 217 insertions(+) create mode 100644 contrib/nssciphersuite/README.txt create mode 100755 contrib/nssciphersuite/nssciphersuite.py diff --git a/contrib/nssciphersuite/README.txt b/contrib/nssciphersuite/README.txt new file mode 100644 index 0000000000000000000000000000000000000000..89bafff560eb497089474e2d8a0b1b853d5c5bdf --- /dev/null +++ b/contrib/nssciphersuite/README.txt @@ -0,0 +1,38 @@ +Cipher suite for mod_nss +------------------------ + +The nssciphersuite.py script parses mod_nss' nss_engine_cipher.c file and +creates a list of secure cipher suites for TLS. The script filters out +insecure, obsolete and slow ciphers according to some rules. + +As of January 2016 and mod_nss 1.0.12 the cipher suite list contains 14 +cipher suites for TLS 1.0, 1.1 and 1.2 for RSA and ECDSA certificates. The +cipher suite list also supports Perfect Forward Secrecy with ephemeral ECDH +key exchange. https://www.ssllabs.com/ gives a 'A' grade. + +Note: +No suite is compatible with IE 8 and earlier on Windows XP. If you need IE 8 +support, append "+rsa_3des_sha" to enable TLS_RSA_WITH_3DES_EDE_CBC_SHA. + +# disabled cipher attributes: SSL_3DES, SSL_CAMELLIA, SSL_CAMELLIA128, SSL_CAMELLIA256, SSL_DES, SSL_DSS, SSL_MD5, SSL_RC2, SSL_RC4, SSL_aDSS, SSL_aNULL, SSL_eNULL, SSL_kECDHe, SSL_kECDHr, kECDH +# weak strength: SSL_EXPORT40, SSL_EXPORT56, SSL_LOW, SSL_STRONG_NONE +# enabled cipher suites: +# TLS_RSA_WITH_AES_128_CBC_SHA256 +# TLS_RSA_WITH_AES_256_CBC_SHA256 +# TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 +# TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA +# TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 +# TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA +# TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 +# TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA +# TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 +# TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA +# TLS_RSA_WITH_AES_128_GCM_SHA256 +# TLS_RSA_WITH_AES_128_CBC_SHA +# TLS_RSA_WITH_AES_256_GCM_SHA384 +# TLS_RSA_WITH_AES_256_CBC_SHA +# + +NSSCipherSuite +aes_128_sha_256,+aes_256_sha_256,+ecdhe_ecdsa_aes_128_gcm_sha_256,+ecdhe_ecdsa_aes_128_sha,+ecdhe_ecdsa_aes_256_gcm_sha_384,+ecdhe_ecdsa_aes_256_sha,+ecdhe_rsa_aes_128_gcm_sha_256,+ecdhe_rsa_aes_128_sha,+ecdhe_rsa_aes_256_gcm_sha_384,+ecdhe_rsa_aes_256_sha,+rsa_aes_128_gcm_sha_256,+rsa_aes_128_sha,+rsa_aes_256_gcm_sha_384,+rsa_aes_256_sha + + diff --git a/contrib/nssciphersuite/nssciphersuite.py b/contrib/nssciphersuite/nssciphersuite.py new file mode 100755 index 0000000000000000000000000000000000000000..95252512a38d90bbcf12e5d362de8bf509c3e854 --- /dev/null +++ b/contrib/nssciphersuite/nssciphersuite.py @@ -0,0 +1,147 @@ +#!/usr/bin/python3 +# +# Authors: +# Christian Heimes <chei...@redhat.com> +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; version 2 of the License. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License along +# with this program; if not, write to the Free Software Foundation, Inc., +# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. +# +# Copyright (C) 2016 Red Hat, Inc. +# All rights reserved. +# +"""Generate safe NSSCipherSuite stanza for mod_nss +""" +from __future__ import print_function + +import operator +import re +import urllib.request # pylint: disable=E0611 + +SOURCE = "https://git.fedorahosted.org/cgit/mod_nss.git/plain/nss_engine_cipher.c"; + +CIPHER_RE = re.compile( + r'\s*\{' + r'\"(?P<name>\w+)\",\s*' + r'(?P<num>(TLS|SSL)_\w+),\s*' + r'\"(?P<openssl_name>[\w-]+)\",\s*' + r'(?P<attr>[\w|]+),\s*' + r'(?P<version>\w+),\s*' + r'(?P<strength>\w+),\s*' + r'(?P<bits>\d+),\s*' + r'(?P<alg_bits>\d+)' +) + +DISABLED_CIPHERS = { + # ciphers without encryption or authentication + 'SSL_eNULL', 'SSL_aNULL', + # MD5 is broken + # SHA-1 is still required as PRF algorithm for TLSv1.0 + 'SSL_MD5', + # RC2 and RC4 stream ciphers are broken. + 'SSL_RC2', 'SSL_RC4', + # DES is broken and Triple DES is too weak. + 'SSL_DES', 'SSL_3DES', + # DSA is problematic. + 'SSL_DSS', 'SSL_aDSS', + # prefer AES over Camellia. + 'SSL_CAMELLIA128', 'SSL_CAMELLIA256', 'SSL_CAMELLIA', + # non-ephemeral EC Diffie-Hellmann with fixed parameters are not + # used by common browser and are therefore irrelevant for HTTPS. + 'kECDH', 'SSL_kECDHr', 'SSL_kECDHe' +} + +WEAK_STRENGTH = { + 'SSL_STRONG_NONE', + 'SSL_EXPORT40', + 'SSL_EXPORT56', + 'SSL_LOW' +} + + +def parse_nss_engine_cipher(lines, encoding='utf-8'): + """Parse nss_engine_cipher.c and get list of ciphers + + :param lines: iterable or list of lines + :param encoding: default encoding + :return: list of cipher dicts + """ + ciphers = [] + start = False + for line in lines: + if not isinstance(line, str): + line = line.decode(encoding) + + if line.startswith('cipher_properties'): + start = True + elif not start: + continue + elif line.startswith('};'): + break + + mo = CIPHER_RE.match(line) + if not mo: + continue + + match = mo.groupdict() + match['attr'] = set(match['attr'].split('|')) + match['bits'] = int(match['bits']) + match['alg_bits'] = int(match['alg_bits']) + + # some cipher elemets aren't flagged + for algo in ['SHA256', 'SHA384']: + if match['num'].endswith(algo): + match['attr'].add('SSL_{}'.format(algo)) + + # cipher block chaining isn't tracked + if '_CBC' in match['num']: + match['attr'].add('SSL_CBC') + + if match['attr'].intersection(DISABLED_CIPHERS): + match['enabled'] = False + elif match['strength'] in WEAK_STRENGTH: + match['enabled'] = False + else: + match['enabled'] = True + + # EECDH + AES-CBC and large hash functions is slow and not more secure + if (match['attr'].issuperset({'SSL_CBC', 'SSL_kEECDH'}) and + match['attr'].intersection({'SSL_SHA256', 'SSL_SHA384'})): + match['enabled'] = False + + ciphers.append(match) + + ciphers.sort(key=operator.itemgetter('name')) + return ciphers + + +def main(): + with urllib.request.urlopen(SOURCE) as r: # pylint: disable=E1101 + ciphers = parse_nss_engine_cipher(r) + # with open('nss_engine_cipher.c') as f: + # ciphers = parse_nss_engine_cipher(f) + + print("# disabled cipher attributes: {}".format( + ', '.join(sorted(DISABLED_CIPHERS)))) + print("# weak strength: {}".format(', '.join(sorted(WEAK_STRENGTH)))) + print("# enabled cipher suites:") + suite = [] + for cipher in ciphers: + if cipher['enabled']: + print("# {:36}".format(cipher['num'])) + suite.append('+{}'.format(cipher['name'])) + print() + print("NSSCipherSuite {}".format(','.join(suite))) + + +if __name__ == '__main__': + main() diff --git a/ipaserver/install/httpinstance.py b/ipaserver/install/httpinstance.py index 3b46dce82cae017328c9555c543e78b64e642c89..ef339d9e91fa37184c865aed5975891b23793440 100644 --- a/ipaserver/install/httpinstance.py +++ b/ipaserver/install/httpinstance.py @@ -57,6 +57,18 @@ SELINUX_BOOLEAN_SETTINGS = dict( KDCPROXY_USER = 'kdcproxy' HTTPD_USER = constants.HTTPD_USER +# See contrib/nsscipersuite/nssciphersuite.py +NSS_CIPHER_SUITE = [ + '+aes_128_sha_256', '+aes_256_sha_256', + '+ecdhe_ecdsa_aes_128_gcm_sha_256', '+ecdhe_ecdsa_aes_128_sha', + '+ecdhe_ecdsa_aes_256_gcm_sha_384', '+ecdhe_ecdsa_aes_256_sha', + '+ecdhe_rsa_aes_128_gcm_sha_256', '+ecdhe_rsa_aes_128_sha', + '+ecdhe_rsa_aes_256_gcm_sha_384', '+ecdhe_rsa_aes_256_sha', + '+rsa_aes_128_gcm_sha_256', '+rsa_aes_128_sha', + '+rsa_aes_256_gcm_sha_384', '+rsa_aes_256_sha' +] + + def httpd_443_configured(): """ We now allow mod_ssl to be installed so don't automatically disable it. @@ -146,6 +158,8 @@ class HTTPInstance(service.Service): self.step("setting mod_nss port to 443", self.__set_mod_nss_port) + self.step("setting mod_nss cipher suite", + self.set_mod_nss_cipher_suite) self.step("setting mod_nss protocol list to TLSv1.0 - TLSv1.2", self.set_mod_nss_protocol) self.step("setting mod_nss password file", self.__set_mod_nss_passwordfile) @@ -255,6 +269,10 @@ class HTTPInstance(service.Service): installutils.set_directive(paths.HTTPD_NSS_CONF, 'NSSRenegotiation', 'on', False) installutils.set_directive(paths.HTTPD_NSS_CONF, 'NSSRequireSafeNegotiation', 'on', False) + def set_mod_nss_cipher_suite(self): + ciphers = ','.join(NSS_CIPHER_SUITE) + installutils.set_directive(paths.HTTPD_NSS_CONF, 'NSSCipherSuite', ciphers, False) + def __set_mod_nss_passwordfile(self): installutils.set_directive(paths.HTTPD_NSS_CONF, 'NSSPassPhraseDialog', 'file:' + paths.HTTPD_PASSWORD_CONF) diff --git a/ipaserver/install/server/upgrade.py b/ipaserver/install/server/upgrade.py index 20379f19c652cb0b5911a4c2f1c67eae7f763379..73f528e9a224441d35d7ce3cb88c1bf9f3895ffb 100644 --- a/ipaserver/install/server/upgrade.py +++ b/ipaserver/install/server/upgrade.py @@ -1361,6 +1361,19 @@ def update_mod_nss_protocol(http): sysupgrade.set_upgrade_state('nss.conf', 'protocol_updated_tls12', True) + +def update_mod_nss_cipher_suite(http): + root_logger.info('[Updating mod_nss cipher suite]') + + if sysupgrade.get_upgrade_state('nss.conf', 'cipher_suite_updated'): + root_logger.info("Cipher suite already updated") + return + + http.set_mod_nss_cipher_suite() + + sysupgrade.set_upgrade_state('nss.conf', 'cipher_suite_updated', True) + + def ds_enable_sidgen_extdom_plugins(ds): """For AD trust agents, make sure we enable sidgen and extdom plugins """ @@ -1541,6 +1554,7 @@ def upgrade_configuration(): http.stop() update_mod_nss_protocol(http) + update_mod_nss_cipher_suite(http) fix_trust_flags() export_kra_agent_pem() http.start() -- 2.5.0
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