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# SPDX-License-Identifier: LGPL-2.1-or-later
# Copyright (c) 2019 Red Hat, Inc.
# Copyright (c) 2019 Tomáš Mráz <tmraz@fedoraproject.org>
from subprocess import call, CalledProcessError
from tempfile import mkstemp
import os
from .configgenerator import ConfigGenerator
class OpenSSHGenerator(ConfigGenerator):
_FORMAT_STRING = ''
cipher_map = {
'AES-256-GCM':'aes256-gcm@openssh.com',
'AES-256-CTR':'aes256-ctr',
'AES-192-GCM':'', # not supported
'AES-192-CTR':'aes192-ctr',
'AES-128-GCM':'aes128-gcm@openssh.com',
'AES-128-CTR':'aes128-ctr',
'CHACHA20-POLY1305':'chacha20-poly1305@openssh.com',
'CAMELLIA-256-GCM':'',
'AES-256-CCM':'',
'AES-192-CCM':'',
'AES-128-CCM':'',
'CAMELLIA-128-GCM':'',
'AES-256-CBC':'aes256-cbc',
'AES-192-CBC':'aes192-cbc',
'AES-128-CBC':'aes128-cbc',
'CAMELLIA-256-CBC':'',
'CAMELLIA-128-CBC':'',
'RC4-128':'',
'DES-CBC':'',
'CAMELLIA-128-CTS':'',
'3DES-CBC':'3des-cbc'
}
mac_map_etm = {
'HMAC-MD5':'hmac-md5-etm@openssh.com',
'UMAC-64':'umac-64-etm@openssh.com',
'UMAC-128':'umac-128-etm@openssh.com',
'HMAC-SHA1':'hmac-sha1-etm@openssh.com',
'HMAC-SHA2-256':'hmac-sha2-256-etm@openssh.com',
'HMAC-SHA2-512':'hmac-sha2-512-etm@openssh.com'
}
mac_map = {
'HMAC-MD5':'hmac-md5',
'UMAC-64':'umac-64@openssh.com',
'UMAC-128':'umac-128@openssh.com',
'HMAC-SHA1':'hmac-sha1',
'HMAC-SHA2-256':'hmac-sha2-256',
'HMAC-SHA2-512':'hmac-sha2-512'
}
kx_map = {
'ECDHE-SECP521R1-SHA2-512':'ecdh-sha2-nistp521',
'ECDHE-SECP384R1-SHA2-384':'ecdh-sha2-nistp384',
'ECDHE-SECP256R1-SHA2-256':'ecdh-sha2-nistp256',
'ECDHE-X25519-SHA2-256':'curve25519-sha256,curve25519-sha256@libssh.org',
'DHE-FFDHE-1024-SHA1':'diffie-hellman-group1-sha1',
'DHE-FFDHE-2048-SHA1':'diffie-hellman-group14-sha1',
'DHE-FFDHE-2048-SHA2-256':'diffie-hellman-group14-sha256',
'DHE-FFDHE-4096-SHA2-512':'diffie-hellman-group16-sha512',
'DHE-FFDHE-8192-SHA2-512':'diffie-hellman-group18-sha512',
}
gx_map = {
'DHE-SHA1':'diffie-hellman-group-exchange-sha1',
'DHE-SHA2-256':'diffie-hellman-group-exchange-sha256',
}
gss_kx_map = {
'DHE-GSS-SHA1':'gss-gex-sha1-',
'DHE-GSS-FFDHE-1024-SHA1':'gss-group1-sha1-',
'DHE-GSS-FFDHE-2048-SHA1':'gss-group14-sha1-',
'DHE-GSS-FFDHE-2048-SHA2-256':'gss-group14-sha256-',
'ECDHE-GSS-SECP256R1-SHA2-256':'gss-nistp256-sha256-',
'ECDHE-GSS-X25519-SHA2-256':'gss-curve25519-sha256-',
'DHE-GSS-FFDHE-4096-SHA2-512':'gss-group16-sha512-',
}
sign_map = {
'RSA-SHA1':'ssh-rsa',
'DSA-SHA1':'ssh-dss',
'RSA-SHA2-256':'rsa-sha2-256',
'RSA-SHA2-512':'rsa-sha2-512',
'ECDSA-SHA2-256':'ecdsa-sha2-nistp256',
'ECDSA-SHA2-384':'ecdsa-sha2-nistp384',
'ECDSA-SHA2-512':'ecdsa-sha2-nistp521',
'EDDSA-ED25519':'ssh-ed25519',
}
sign_map_certs = {
'RSA-SHA1':'ssh-rsa-cert-v01@openssh.com',
'DSA-SHA1':'ssh-dss-cert-v01@openssh.com',
'RSA-SHA2-256':'rsa-sha2-256-cert-v01@openssh.com',
'RSA-SHA2-512':'rsa-sha2-512-cert-v01@openssh.com',
'ECDSA-SHA2-256':'ecdsa-sha2-nistp256-cert-v01@openssh.com',
'ECDSA-SHA2-384':'ecdsa-sha2-nistp384-cert-v01@openssh.com',
'ECDSA-SHA2-512':'ecdsa-sha2-nistp521-cert-v01@openssh.com',
'EDDSA-ED25519':'ssh-ed25519-cert-v01@openssh.com',
}
@classmethod
def generate_options(cls, policy, local_kx_map, local_gss_kx_map, do_host_key):
p = policy.enabled
cfg = ''
sep = ','
s = ''
for i in p['cipher']:
try:
s = cls.append(s, cls.cipher_map[i], sep)
except KeyError:
pass
if s:
cfg += cls._FORMAT_STRING.format('Ciphers', s)
s = ''
if policy.integers['ssh_etm']:
for i in p['mac']:
try:
s = cls.append(s, cls.mac_map_etm[i], sep)
except KeyError:
pass
for i in p['mac']:
try:
s = cls.append(s, cls.mac_map[i], sep)
except KeyError:
pass
if s:
cfg += cls._FORMAT_STRING.format('MACs', s)
s = ''
gss = ''
for kx in p['key_exchange']:
for h in p['hash']:
if policy.integers['arbitrary_dh_groups']:
try:
val = cls.gx_map[kx + '-' + h]
s = cls.append(s, val, sep)
except KeyError:
pass
try:
val = local_gss_kx_map[kx + '-' + h]
gss = cls.append(gss, val, sep)
except KeyError:
pass
for g in p['group']:
try:
val = local_kx_map[kx + '-' + g + '-' + h]
s = cls.append(s, val, sep)
except KeyError:
pass
try:
val = local_gss_kx_map[kx + '-' + g + '-' + h]
gss = cls.append(gss, val, sep)
except KeyError:
pass
if gss:
cfg += cls._FORMAT_STRING.format('GSSAPIKexAlgorithms', gss)
else:
cfg += cls._FORMAT_STRING.format('GSSAPIKeyExchange', 'no')
if s:
cfg += cls._FORMAT_STRING.format('KexAlgorithms', s)
s = ''
for i in p['sign']:
try:
s = cls.append(s, cls.sign_map[i], sep)
except KeyError:
pass
if policy.integers['ssh_certs'] == 1:
try:
s = cls.append(s, cls.sign_map_certs[i], sep)
except KeyError:
pass
if s:
# As OpenSSH currently ignores existing known host
# entries with this setting we cannot use it on client.
# Otherwise we could break existing users.
if do_host_key:
cfg += cls._FORMAT_STRING.format('HostKeyAlgorithms', s)
cfg += cls._FORMAT_STRING.format('PubkeyAcceptedKeyTypes', s)
s = ''
for i in p['sign']:
try:
s = cls.append(s, cls.sign_map[i], sep)
except KeyError:
pass
if s:
cfg += cls._FORMAT_STRING.format('CASignatureAlgorithms', s)
return cfg
class OpenSSHClientGenerator(OpenSSHGenerator):
CONFIG_NAME = 'openssh'
SCOPES = {'ssh', 'openssh', 'openssh-client'}
_FORMAT_STRING = '{0} {1}\n'
@classmethod
def generate_config(cls, policy):
local_kx_map = dict(cls.kx_map)
local_gss_kx_map = dict(cls.gss_kx_map)
return cls.generate_options(policy, local_kx_map, local_gss_kx_map, False)
@classmethod
def test_config(cls, config):
if not os.access('/usr/bin/ssh', os.X_OK):
return True
fd, path = mkstemp()
ret = 255
try:
with os.fdopen(fd, 'w') as f:
f.write(config)
try:
ret = call('/usr/bin/ssh -G -F ' + path +
' bogus654_server >/dev/null',
shell=True)
except CalledProcessError:
cls.eprint("/usr/bin/ssh: Execution failed")
finally:
os.unlink(path)
if ret:
cls.eprint("There is an error in OpenSSH generated policy")
cls.eprint("Policy:\n%s" % config)
return False
return True
class OpenSSHServerGenerator(OpenSSHGenerator):
CONFIG_NAME = 'opensshserver'
SCOPES = {'ssh', 'openssh', 'openssh-server'}
# We need restart here, since systemd needs to pick up new command line options
RELOAD_CMD = 'systemctl try-restart sshd.service 2>/dev/null || :\n'
_FORMAT_STRING = '-o{0}={1} '
@classmethod
def generate_config(cls, policy):
# Difference from client, keep group1 disabled on server
local_kx_map = dict(cls.kx_map)
local_gss_kx_map = dict(cls.gss_kx_map)
del local_kx_map['DHE-FFDHE-1024-SHA1']
del local_gss_kx_map['DHE-GSS-FFDHE-1024-SHA1']
cfg = cls.generate_options(policy, local_kx_map, local_gss_kx_map, True)
cfg = cfg.rstrip()
return 'CRYPTO_POLICY=\'' + cfg + '\''
@classmethod
def _test_setup(cls):
_fd, path = mkstemp()
os.unlink(path)
ret = 255
try:
ret = call('/usr/bin/ssh-keygen -t rsa -b 2048 -f ' + path +
' -N "" >/dev/null',
shell=True)
except CalledProcessError:
cls.eprint("/usr/bin/ssh-keygen: Execution failed")
if ret:
cls.eprint("SSH Keygen failed when testing OpenSSH server policy")
return ''
return path
@classmethod
def _test_cleanup(cls, path):
if path:
os.unlink(path)
@classmethod
def test_config(cls, config):
if not os.access('/usr/sbin/sshd', os.X_OK):
return True
host_key_filename = cls._test_setup()
if not host_key_filename:
return False
fd, path = mkstemp()
ret = 255
try:
with os.fdopen(fd, 'w') as f:
f.write(config)
try:
ret = call('/usr/bin/bash -c \'source ' + path +
' && /usr/sbin/sshd -T $CRYPTO_POLICY -h ' +
host_key_filename +
' -f /dev/null\' >/dev/null',
shell=True)
except CalledProcessError:
cls.eprint("/usr/sbin/sshd: Execution failed")
finally:
os.unlink(path)
cls._test_cleanup(host_key_filename)
if ret:
cls.eprint("There is an error in OpenSSH server generated policy")
cls.eprint("Policy:\n%s" % config)
return False
return True
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