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# Copyright 2016 Canonical Limited.
#
# This file is part of charm-helpers.
#
# charm-helpers is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License version 3 as
# published by the Free Software Foundation.
#
# charm-helpers 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with charm-helpers. If not, see <http://www.gnu.org/licenses/>.
import os
import platform
import re
import six
import subprocess
from charmhelpers.core.hookenv import (
log,
INFO,
WARNING,
)
from charmhelpers.contrib.hardening import utils
from charmhelpers.contrib.hardening.audits.file import (
FilePermissionAudit,
TemplatedFile,
)
from charmhelpers.contrib.hardening.host import TEMPLATES_DIR
SYSCTL_DEFAULTS = """net.ipv4.ip_forward=%(net_ipv4_ip_forward)s
net.ipv6.conf.all.forwarding=%(net_ipv6_conf_all_forwarding)s
net.ipv4.conf.all.rp_filter=1
net.ipv4.conf.default.rp_filter=1
net.ipv4.icmp_echo_ignore_broadcasts=1
net.ipv4.icmp_ignore_bogus_error_responses=1
net.ipv4.icmp_ratelimit=100
net.ipv4.icmp_ratemask=88089
net.ipv6.conf.all.disable_ipv6=%(net_ipv6_conf_all_disable_ipv6)s
net.ipv4.tcp_timestamps=%(net_ipv4_tcp_timestamps)s
net.ipv4.conf.all.arp_ignore=%(net_ipv4_conf_all_arp_ignore)s
net.ipv4.conf.all.arp_announce=%(net_ipv4_conf_all_arp_announce)s
net.ipv4.tcp_rfc1337=1
net.ipv4.tcp_syncookies=1
net.ipv4.conf.all.shared_media=1
net.ipv4.conf.default.shared_media=1
net.ipv4.conf.all.accept_source_route=0
net.ipv4.conf.default.accept_source_route=0
net.ipv4.conf.all.accept_redirects=0
net.ipv4.conf.default.accept_redirects=0
net.ipv6.conf.all.accept_redirects=0
net.ipv6.conf.default.accept_redirects=0
net.ipv4.conf.all.secure_redirects=0
net.ipv4.conf.default.secure_redirects=0
net.ipv4.conf.all.send_redirects=0
net.ipv4.conf.default.send_redirects=0
net.ipv4.conf.all.log_martians=0
net.ipv6.conf.default.router_solicitations=0
net.ipv6.conf.default.accept_ra_rtr_pref=0
net.ipv6.conf.default.accept_ra_pinfo=0
net.ipv6.conf.default.accept_ra_defrtr=0
net.ipv6.conf.default.autoconf=0
net.ipv6.conf.default.dad_transmits=0
net.ipv6.conf.default.max_addresses=1
net.ipv6.conf.all.accept_ra=0
net.ipv6.conf.default.accept_ra=0
kernel.modules_disabled=%(kernel_modules_disabled)s
kernel.sysrq=%(kernel_sysrq)s
fs.suid_dumpable=%(fs_suid_dumpable)s
kernel.randomize_va_space=2
"""
def get_audits():
"""Get OS hardening sysctl audits.
:returns: dictionary of audits
"""
audits = []
settings = utils.get_settings('os')
# Apply the sysctl settings which are configured to be applied.
audits.append(SysctlConf())
# Make sure that only root has access to the sysctl.conf file, and
# that it is read-only.
audits.append(FilePermissionAudit('/etc/sysctl.conf',
user='root',
group='root', mode=0o0440))
# If module loading is not enabled, then ensure that the modules
# file has the appropriate permissions and rebuild the initramfs
if not settings['security']['kernel_enable_module_loading']:
audits.append(ModulesTemplate())
return audits
class ModulesContext(object):
def __call__(self):
settings = utils.get_settings('os')
with open('/proc/cpuinfo', 'r') as fd:
cpuinfo = fd.readlines()
for line in cpuinfo:
match = re.search(r"^vendor_id\s+:\s+(.+)", line)
if match:
vendor = match.group(1)
if vendor == "GenuineIntel":
vendor = "intel"
elif vendor == "AuthenticAMD":
vendor = "amd"
ctxt = {'arch': platform.processor(),
'cpuVendor': vendor,
'desktop_enable': settings['general']['desktop_enable']}
return ctxt
class ModulesTemplate(object):
def __init__(self):
super(ModulesTemplate, self).__init__('/etc/initramfs-tools/modules',
ModulesContext(),
templates_dir=TEMPLATES_DIR,
user='root', group='root',
mode=0o0440)
def post_write(self):
subprocess.check_call(['update-initramfs', '-u'])
class SysCtlHardeningContext(object):
def __call__(self):
settings = utils.get_settings('os')
ctxt = {'sysctl': {}}
log("Applying sysctl settings", level=INFO)
extras = {'net_ipv4_ip_forward': 0,
'net_ipv6_conf_all_forwarding': 0,
'net_ipv6_conf_all_disable_ipv6': 1,
'net_ipv4_tcp_timestamps': 0,
'net_ipv4_conf_all_arp_ignore': 0,
'net_ipv4_conf_all_arp_announce': 0,
'kernel_sysrq': 0,
'fs_suid_dumpable': 0,
'kernel_modules_disabled': 1}
if settings['sysctl']['ipv6_enable']:
extras['net_ipv6_conf_all_disable_ipv6'] = 0
if settings['sysctl']['forwarding']:
extras['net_ipv4_ip_forward'] = 1
extras['net_ipv6_conf_all_forwarding'] = 1
if settings['sysctl']['arp_restricted']:
extras['net_ipv4_conf_all_arp_ignore'] = 1
extras['net_ipv4_conf_all_arp_announce'] = 2
if settings['security']['kernel_enable_module_loading']:
extras['kernel_modules_disabled'] = 0
if settings['sysctl']['kernel_enable_sysrq']:
sysrq_val = settings['sysctl']['kernel_secure_sysrq']
extras['kernel_sysrq'] = sysrq_val
if settings['security']['kernel_enable_core_dump']:
extras['fs_suid_dumpable'] = 1
settings.update(extras)
for d in (SYSCTL_DEFAULTS % settings).split():
d = d.strip().partition('=')
key = d[0].strip()
path = os.path.join('/proc/sys', key.replace('.', '/'))
if not os.path.exists(path):
log("Skipping '%s' since '%s' does not exist" % (key, path),
level=WARNING)
continue
ctxt['sysctl'][key] = d[2] or None
# Translate for python3
return {'sysctl_settings':
[(k, v) for k, v in six.iteritems(ctxt['sysctl'])]}
class SysctlConf(TemplatedFile):
"""An audit check for sysctl settings."""
def __init__(self):
self.conffile = '/etc/sysctl.d/99-juju-hardening.conf'
super(SysctlConf, self).__init__(self.conffile,
SysCtlHardeningContext(),
template_dir=TEMPLATES_DIR,
user='root', group='root',
mode=0o0440)
def post_write(self):
try:
subprocess.check_call(['sysctl', '-p', self.conffile])
except subprocess.CalledProcessError as e:
# NOTE: on some systems if sysctl cannot apply all settings it
# will return non-zero as well.
log("sysctl command returned an error (maybe some "
"keys could not be set) - %s" % (e),
level=WARNING)
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