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# Copyright 2014-2015 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/>.
"""
This module contains helpers to add and remove ufw rules.
Examples:
- open SSH port for subnet 10.0.3.0/24:
>>> from charmhelpers.contrib.network import ufw
>>> ufw.enable()
>>> ufw.grant_access(src='10.0.3.0/24', dst='any', port='22', proto='tcp')
- open service by name as defined in /etc/services:
>>> from charmhelpers.contrib.network import ufw
>>> ufw.enable()
>>> ufw.service('ssh', 'open')
- close service by port number:
>>> from charmhelpers.contrib.network import ufw
>>> ufw.enable()
>>> ufw.service('4949', 'close') # munin
"""
import re
import os
import subprocess
from charmhelpers.core import hookenv
from charmhelpers.core.kernel import modprobe, is_module_loaded
__author__ = "Felipe Reyes <felipe.reyes@canonical.com>"
class UFWError(Exception):
pass
class UFWIPv6Error(UFWError):
pass
def is_enabled():
"""
Check if `ufw` is enabled
:returns: True if ufw is enabled
"""
output = subprocess.check_output(['ufw', 'status'],
universal_newlines=True,
env={'LANG': 'en_US',
'PATH': os.environ['PATH']})
m = re.findall(r'^Status: active\n', output, re.M)
return len(m) >= 1
def is_ipv6_ok(soft_fail=False):
"""
Check if IPv6 support is present and ip6tables functional
:param soft_fail: If set to True and IPv6 support is broken, then reports
that the host doesn't have IPv6 support, otherwise a
UFWIPv6Error exception is raised.
:returns: True if IPv6 is working, False otherwise
"""
# do we have IPv6 in the machine?
if os.path.isdir('/proc/sys/net/ipv6'):
# is ip6tables kernel module loaded?
if not is_module_loaded('ip6_tables'):
# ip6tables support isn't complete, let's try to load it
try:
modprobe('ip6_tables')
# great, we can load the module
return True
except subprocess.CalledProcessError as ex:
hookenv.log("Couldn't load ip6_tables module: %s" % ex.output,
level="WARN")
# we are in a world where ip6tables isn't working
if soft_fail:
# so we inform that the machine doesn't have IPv6
return False
else:
raise UFWIPv6Error("IPv6 firewall support broken")
else:
# the module is present :)
return True
else:
# the system doesn't have IPv6
return False
def disable_ipv6():
"""
Disable ufw IPv6 support in /etc/default/ufw
"""
exit_code = subprocess.call(['sed', '-i', 's/IPV6=.*/IPV6=no/g',
'/etc/default/ufw'])
if exit_code == 0:
hookenv.log('IPv6 support in ufw disabled', level='INFO')
else:
hookenv.log("Couldn't disable IPv6 support in ufw", level="ERROR")
raise UFWError("Couldn't disable IPv6 support in ufw")
def enable(soft_fail=False):
"""
Enable ufw
:param soft_fail: If set to True silently disables IPv6 support in ufw,
otherwise a UFWIPv6Error exception is raised when IP6
support is broken.
:returns: True if ufw is successfully enabled
"""
if is_enabled():
return True
if not is_ipv6_ok(soft_fail):
disable_ipv6()
output = subprocess.check_output(['ufw', 'enable'],
universal_newlines=True,
env={'LANG': 'en_US',
'PATH': os.environ['PATH']})
m = re.findall('^Firewall is active and enabled on system startup\n',
output, re.M)
hookenv.log(output, level='DEBUG')
if len(m) == 0:
hookenv.log("ufw couldn't be enabled", level='WARN')
return False
else:
hookenv.log("ufw enabled", level='INFO')
return True
def disable():
"""
Disable ufw
:returns: True if ufw is successfully disabled
"""
if not is_enabled():
return True
output = subprocess.check_output(['ufw', 'disable'],
universal_newlines=True,
env={'LANG': 'en_US',
'PATH': os.environ['PATH']})
m = re.findall(r'^Firewall stopped and disabled on system startup\n',
output, re.M)
hookenv.log(output, level='DEBUG')
if len(m) == 0:
hookenv.log("ufw couldn't be disabled", level='WARN')
return False
else:
hookenv.log("ufw disabled", level='INFO')
return True
def default_policy(policy='deny', direction='incoming'):
"""
Changes the default policy for traffic `direction`
:param policy: allow, deny or reject
:param direction: traffic direction, possible values: incoming, outgoing,
routed
"""
if policy not in ['allow', 'deny', 'reject']:
raise UFWError(('Unknown policy %s, valid values: '
'allow, deny, reject') % policy)
if direction not in ['incoming', 'outgoing', 'routed']:
raise UFWError(('Unknown direction %s, valid values: '
'incoming, outgoing, routed') % direction)
output = subprocess.check_output(['ufw', 'default', policy, direction],
universal_newlines=True,
env={'LANG': 'en_US',
'PATH': os.environ['PATH']})
hookenv.log(output, level='DEBUG')
m = re.findall("^Default %s policy changed to '%s'\n" % (direction,
policy),
output, re.M)
if len(m) == 0:
hookenv.log("ufw couldn't change the default policy to %s for %s"
% (policy, direction), level='WARN')
return False
else:
hookenv.log("ufw default policy for %s changed to %s"
% (direction, policy), level='INFO')
return True
def modify_access(src, dst='any', port=None, proto=None, action='allow',
index=None):
"""
Grant access to an address or subnet
:param src: address (e.g. 192.168.1.234) or subnet
(e.g. 192.168.1.0/24).
:param dst: destiny of the connection, if the machine has multiple IPs and
connections to only one of those have to accepted this is the
field has to be set.
:param port: destiny port
:param proto: protocol (tcp or udp)
:param action: `allow` or `delete`
:param index: if different from None the rule is inserted at the given
`index`.
"""
if not is_enabled():
hookenv.log('ufw is disabled, skipping modify_access()', level='WARN')
return
if action == 'delete':
cmd = ['ufw', 'delete', 'allow']
elif index is not None:
cmd = ['ufw', 'insert', str(index), action]
else:
cmd = ['ufw', action]
if src is not None:
cmd += ['from', src]
if dst is not None:
cmd += ['to', dst]
if port is not None:
cmd += ['port', str(port)]
if proto is not None:
cmd += ['proto', proto]
hookenv.log('ufw {}: {}'.format(action, ' '.join(cmd)), level='DEBUG')
p = subprocess.Popen(cmd, stdout=subprocess.PIPE)
(stdout, stderr) = p.communicate()
hookenv.log(stdout, level='INFO')
if p.returncode != 0:
hookenv.log(stderr, level='ERROR')
hookenv.log('Error running: {}, exit code: {}'.format(' '.join(cmd),
p.returncode),
level='ERROR')
def grant_access(src, dst='any', port=None, proto=None, index=None):
"""
Grant access to an address or subnet
:param src: address (e.g. 192.168.1.234) or subnet
(e.g. 192.168.1.0/24).
:param dst: destiny of the connection, if the machine has multiple IPs and
connections to only one of those have to accepted this is the
field has to be set.
:param port: destiny port
:param proto: protocol (tcp or udp)
:param index: if different from None the rule is inserted at the given
`index`.
"""
return modify_access(src, dst=dst, port=port, proto=proto, action='allow',
index=index)
def revoke_access(src, dst='any', port=None, proto=None):
"""
Revoke access to an address or subnet
:param src: address (e.g. 192.168.1.234) or subnet
(e.g. 192.168.1.0/24).
:param dst: destiny of the connection, if the machine has multiple IPs and
connections to only one of those have to accepted this is the
field has to be set.
:param port: destiny port
:param proto: protocol (tcp or udp)
"""
return modify_access(src, dst=dst, port=port, proto=proto, action='delete')
def service(name, action):
"""
Open/close access to a service
:param name: could be a service name defined in `/etc/services` or a port
number.
:param action: `open` or `close`
"""
if action == 'open':
subprocess.check_output(['ufw', 'allow', str(name)],
universal_newlines=True)
elif action == 'close':
subprocess.check_output(['ufw', 'delete', 'allow', str(name)],
universal_newlines=True)
else:
raise UFWError(("'{}' not supported, use 'allow' "
"or 'delete'").format(action))
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