friwall/web/system.py

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#!/usr/bin/python3
import collections
import email.message
import getpass
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import multiprocessing
import os
import pathlib
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import shutil
import smtplib
import socket
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import subprocess
import sys
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import syslog
import click
import flask
import flask.cli
import ldap3
from . import db
def mail(rcpt, subject, body):
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try:
msg = email.message.EmailMessage()
msg['Subject'] = f'friwall: {subject}'
msg['From'] = f'{getpass.getuser()}@{socket.getfqdn()}'
msg['To'] = rcpt
msg.set_content(body)
with smtplib.SMTP('localhost') as server:
server.send_message(msg)
except Exception as e:
syslog.syslog(f'error sending mail: {e}')
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def init_app(app):
app.cli.add_command(generate)
app.cli.add_command(push)
def run(fun, args=()):
def task():
if os.fork() == 0:
os.setsid()
fun(*args)
multiprocessing.Process(target=task).start()
def save_config():
output = None
try:
# Just load the settings here but keep the database unlocked
# while we load group memberships from LDAP.
with db.locked():
settings = db.read('settings')
groups = db.read('groups')
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# For each user build a list of networks they have access to, based on
# group membership in AD. Only query groups associated with at least one
# network, and query each group only once.
user_networks = collections.defaultdict(set)
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ldap = ldap3.Connection(ldap3.Server(settings.get('ldap_host'), use_ssl=True),
settings.get('ldap_user'), settings.get('ldap_pass'), auto_bind=True)
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ldap.search(settings.get('ldap_base_dn', ''),
'(&(objectClass=user)(objectCategory=person)' + # only people
'(!(userAccountControl:1.2.840.113556.1.4.803:=2))' + # with enabled accounts
f'(memberOf:1.2.840.113556.1.4.1941:={settings.get("user_group", "")}))', # in given group, recursively
attributes=['userPrincipalName', 'memberOf'])
for entry in ldap.entries:
for group in entry.memberOf:
if group in groups:
user_networks[entry.userPrincipalName.value].add(groups[group])
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# Now read the settings again and lock the database while generating
# config files, then increment version before unlocking.
with db.locked():
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settings = db.read('settings')
version = settings['version'] = int(settings.get('version', 0)) + 1
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# Populate IP sets.
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ipsets = collections.defaultdict(set)
for name, network in db.read('ipsets').items():
ipsets[name].update(network.get('ip', ()))
ipsets[f'{name}/6'].update(network.get('ip6', ()))
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# Add registered VPN addresses for each network based on
# LDAP group membership.
wireguard = db.read('wireguard')
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for ip, key in wireguard.items():
for network in user_networks.get(key.get('user', ''), ()):
ipsets[network].add(f'{ip}/32')
if 'ip6' in key:
ipsets[f'{network}/6'].add(f'{key["ip6"]}/128')
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# Create config files.
output = pathlib.Path.home() / 'config' / f'{version}'
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shutil.rmtree(output, ignore_errors=True)
os.makedirs(f'{output}/etc/nftables.d', exist_ok=True)
os.makedirs(f'{output}/etc/wireguard', exist_ok=True)
# Print version.
with open(f'{output}/version', 'w', encoding='utf-8') as f:
print(version, file=f)
# Print nftables sets.
with open(f'{output}/etc/nftables.d/sets.nft', 'w', encoding='utf-8') as f:
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def format_set(name, ips):
return f'''\
set {name} {{
type {"ipv6_addr" if name.endswith('/6') else "ipv4_addr"}; flags interval
{"" if ips else "# "}elements = {{ {", ".join(ips)} }}
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}}'''
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for name, ips in ipsets.items():
print(format_set(name, ips), file=f)
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# Print static NAT (1:1) rules.
with open(f'{output}/etc/nftables.d/netmap.nft', 'w', encoding='utf-8') as f:
def format_map(name, elements):
lines = ',\n'.join(f'{a}: {b}' for a, b in elements)
return f'''\
map {name} {{
type ipv4_addr : interval ipv4_addr; flags interval
elements = {{ {lines} }}
}}
'''
netmap = db.read('netmap') # { private range: public range… }
if netmap:
print(format_map('netmap-out', ((private, public) for private, public in netmap.items())), file=f)
print(format_map('netmap-in', ((public, private) for private, public in netmap.items())), file=f)
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# Print dynamic NAT rules.
with open(f'{output}/etc/nftables.d/nat.nft', 'w', encoding='utf-8') as f:
nat = db.read('nat') # { network name: public range… }
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for network, address in nat.items():
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if address:
print(f'iif @inside oif @outside ip saddr @{network} snat to {address}', file=f)
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# Print forwarding rules.
with open(f'{output}/etc/nftables.d/forward.nft', 'w', encoding='utf-8') as f:
for index, rule in enumerate(db.read('rules')):
if rule.get('enabled') and rule.get('text'):
if 'name' in rule:
print(f'# {index}. {rule["name"]}', file=f)
print(rule['text'], file=f)
print(file=f)
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# Print wireguard config.
with open(f'{output}/etc/wireguard/wg.conf', 'w', encoding='utf-8') as f:
print(f'''\
[Interface]
ListenPort = {settings.get('wg_port', 51820)}
PrivateKey = {settings.get('wg_key')}
''', file=f)
for ip, data in wireguard.items():
print(f'''\
# {data.get('user')}
[Peer]
PublicKey = {data.get('key')}
AllowedIPs = {ip}
''', file=f)
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# Make a config archive in a temporary place, so we don’t send
# incomplete tars.
tar_file = shutil.make_archive(f'{output}-tmp', 'gztar', root_dir=output, owner='root', group='root')
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# Move config archive to the final destination.
os.rename(tar_file, f'{output}.tar.gz')
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# If we get here, write settings with the new version.
db.write('settings', settings)
return True
except Exception as e:
import traceback
e.add_note(f'exception while generating config: {e}')
msg = traceback.format_exc()
if rcpt := settings.get('admin_mail'):
mail(rcpt, 'error generating config', msg)
# TODO this doesn’t seem to work
#syslog.syslog(msg)
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return False
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finally:
# Remove temporary directory.
if output:
shutil.rmtree(output, ignore_errors=True)
@click.command('generate')
@flask.cli.with_appcontext
def generate():
save_config()
@click.command('push')
@click.option('--version', '-v', type=click.INT, default=None, help="Config version to push")
@flask.cli.with_appcontext
def push(version=None):
try:
with db.locked('nodes'):
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if version is None:
version = db.load('settings').get('version', 0)
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nodes = db.read('nodes')
tar_file = pathlib.Path.home() / 'config' / f'{version}.tar.gz'
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errors = []
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for node, node_version in nodes.items():
if node_version != version:
try:
# Push config tarfile to node. There sshd runs a forced command that
# reads in a tarball, copies files to /etc and reloads services.
syslog.syslog(f'updating config for {node} from v{node_version} to v{version}')
result = subprocess.run(['/usr/bin/ssh', '-T', '-o', 'ConnectTimeout=10', f'root@{node}'],
stdin=open(tar_file), capture_output=True, text=True)
if result.returncode == 0:
nodes[node] = version
db.write('nodes', nodes)
syslog.syslog(f'successfully updated config for {node} to v{version}')
else:
raise RuntimeError(f'error updating config to v{version}: {result.stderr}')
except (FileNotFoundError, RuntimeError) as e:
e.add_note(f'error while updating node {node}')
errors.append(e)
if errors:
raise ExceptionGroup('errors while updating nodes', errors)
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except Exception as e:
import traceback
msg = traceback.format_exc()
if rcpt := db.load('settings').get('admin_mail'):
mail(rcpt, 'error updating nodes', msg)
syslog.syslog(msg)