summaryrefslogtreecommitdiff
path: root/src/conf_mode/firewall.py
blob: 3c6aff38621c6b5f70040515ac29c8ef6b8d0bd1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
#!/usr/bin/env python3
#
# Copyright (C) 2021-2022 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# 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, see <http://www.gnu.org/licenses/>.

import os
import re

from glob import glob
from json import loads
from sys import exit

from vyos.base import Warning
from vyos.config import Config
from vyos.configdict import dict_merge
from vyos.configdict import node_changed
from vyos.configdiff import get_config_diff, Diff
from vyos.firewall import get_ips_domains_dict
from vyos.firewall import nft_add_set_elements
from vyos.firewall import nft_flush_set
from vyos.firewall import nft_init_set
from vyos.firewall import nft_update_set_elements
from vyos.template import render
from vyos.util import call
from vyos.util import cmd
from vyos.util import dict_search_args
from vyos.util import process_named_running
from vyos.util import run
from vyos.xml import defaults
from vyos import ConfigError
from vyos import airbag
airbag.enable()

policy_route_conf_script = '/usr/libexec/vyos/conf_mode/policy-route.py'

nftables_conf = '/run/nftables.conf'
nftables_defines_conf = '/run/nftables_defines.conf'

sysfs_config = {
    'all_ping': {'sysfs': '/proc/sys/net/ipv4/icmp_echo_ignore_all', 'enable': '0', 'disable': '1'},
    'broadcast_ping': {'sysfs': '/proc/sys/net/ipv4/icmp_echo_ignore_broadcasts', 'enable': '0', 'disable': '1'},
    'ip_src_route': {'sysfs': '/proc/sys/net/ipv4/conf/*/accept_source_route'},
    'ipv6_receive_redirects': {'sysfs': '/proc/sys/net/ipv6/conf/*/accept_redirects'},
    'ipv6_src_route': {'sysfs': '/proc/sys/net/ipv6/conf/*/accept_source_route', 'enable': '0', 'disable': '-1'},
    'log_martians': {'sysfs': '/proc/sys/net/ipv4/conf/all/log_martians'},
    'receive_redirects': {'sysfs': '/proc/sys/net/ipv4/conf/*/accept_redirects'},
    'send_redirects': {'sysfs': '/proc/sys/net/ipv4/conf/*/send_redirects'},
    'source_validation': {'sysfs': '/proc/sys/net/ipv4/conf/*/rp_filter', 'disable': '0', 'strict': '1', 'loose': '2'},
    'syn_cookies': {'sysfs': '/proc/sys/net/ipv4/tcp_syncookies'},
    'twa_hazards_protection': {'sysfs': '/proc/sys/net/ipv4/tcp_rfc1337'}
}

NAME_PREFIX = 'NAME_'
NAME6_PREFIX = 'NAME6_'

preserve_chains = [
    'INPUT',
    'FORWARD',
    'OUTPUT',
    'VYOS_FW_FORWARD',
    'VYOS_FW_LOCAL',
    'VYOS_FW_OUTPUT',
    'VYOS_POST_FW',
    'VYOS_FRAG_MARK',
    'VYOS_FW6_FORWARD',
    'VYOS_FW6_LOCAL',
    'VYOS_FW6_OUTPUT',
    'VYOS_POST_FW6',
    'VYOS_FRAG6_MARK'
]

nft_iface_chains = ['VYOS_FW_FORWARD', 'VYOS_FW_OUTPUT', 'VYOS_FW_LOCAL']
nft6_iface_chains = ['VYOS_FW6_FORWARD', 'VYOS_FW6_OUTPUT', 'VYOS_FW6_LOCAL']

valid_groups = [
    'address_group',
    'network_group',
    'port_group'
]

snmp_change_type = {
    'unknown': 0,
    'add': 1,
    'delete': 2,
    'change': 3
}
snmp_event_source = 1
snmp_trap_mib = 'VYATTA-TRAP-MIB'
snmp_trap_name = 'mgmtEventTrap'

def get_firewall_interfaces(conf):
    out = {}
    interfaces = conf.get_config_dict(['interfaces'], key_mangling=('-', '_'), get_first_key=True,
                                    no_tag_node_value_mangle=True)
    def find_interfaces(iftype_conf, output={}, prefix=''):
        for ifname, if_conf in iftype_conf.items():
            if 'firewall' in if_conf:
                output[prefix + ifname] = if_conf['firewall']
            for vif in ['vif', 'vif_s', 'vif_c']:
                if vif in if_conf:
                    output.update(find_interfaces(if_conf[vif], output, f'{prefix}{ifname}.'))
        return output
    for iftype, iftype_conf in interfaces.items():
        out.update(find_interfaces(iftype_conf))
    return out

def get_firewall_zones(conf):
    used_v4 = []
    used_v6 = []
    zone_policy = conf.get_config_dict(['zone-policy'], key_mangling=('-', '_'), get_first_key=True,
                                    no_tag_node_value_mangle=True)

    if 'zone' in zone_policy:
        for zone, zone_conf in zone_policy['zone'].items():
            if 'from' in zone_conf:
                for from_zone, from_conf in zone_conf['from'].items():
                    name = dict_search_args(from_conf, 'firewall', 'name')
                    if name:
                        used_v4.append(name)

                    ipv6_name = dict_search_args(from_conf, 'firewall', 'ipv6_name')
                    if ipv6_name:
                        used_v6.append(ipv6_name)

            if 'intra_zone_filtering' in zone_conf:
                name = dict_search_args(zone_conf, 'intra_zone_filtering', 'firewall', 'name')
                if name:
                    used_v4.append(name)

                ipv6_name = dict_search_args(zone_conf, 'intra_zone_filtering', 'firewall', 'ipv6_name')
                if ipv6_name:
                    used_v6.append(ipv6_name)

    return {'name': used_v4, 'ipv6_name': used_v6}

def get_config(config=None):
    if config:
        conf = config
    else:
        conf = Config()
    base = ['firewall']

    firewall = conf.get_config_dict(base, key_mangling=('-', '_'), get_first_key=True,
                                    no_tag_node_value_mangle=True)

    default_values = defaults(base)
    firewall = dict_merge(default_values, firewall)

    firewall['policy_resync'] = bool('group' in firewall or node_changed(conf, base + ['group']))
    firewall['interfaces'] = get_firewall_interfaces(conf)
    firewall['zone_policy'] = get_firewall_zones(conf)

    if 'config_trap' in firewall and firewall['config_trap'] == 'enable':
        diff = get_config_diff(conf)
        firewall['trap_diff'] = diff.get_child_nodes_diff_str(base)
        firewall['trap_targets'] = conf.get_config_dict(['service', 'snmp', 'trap-target'],
                                        key_mangling=('-', '_'), get_first_key=True,
                                        no_tag_node_value_mangle=True)

    return firewall

def verify_rule(firewall, rule_conf, ipv6):
    if 'action' not in rule_conf:
        raise ConfigError('Rule action must be defined')

    if 'fragment' in rule_conf:
        if {'match_frag', 'match_non_frag'} <= set(rule_conf['fragment']):
            raise ConfigError('Cannot specify both "match-frag" and "match-non-frag"')

    if 'limit' in rule_conf:
        if 'rate' in rule_conf['limit']:
            rate_int = re.sub(r'\D', '', rule_conf['limit']['rate'])
            if int(rate_int) < 1:
                raise ConfigError('Limit rate integer cannot be less than 1')

    if 'ipsec' in rule_conf:
        if {'match_ipsec', 'match_non_ipsec'} <= set(rule_conf['ipsec']):
            raise ConfigError('Cannot specify both "match-ipsec" and "match-non-ipsec"')

    if 'recent' in rule_conf:
        if not {'count', 'time'} <= set(rule_conf['recent']):
            raise ConfigError('Recent "count" and "time" values must be defined')

    tcp_flags = dict_search_args(rule_conf, 'tcp', 'flags')
    if tcp_flags:
        if dict_search_args(rule_conf, 'protocol') != 'tcp':
            raise ConfigError('Protocol must be tcp when specifying tcp flags')

        not_flags = dict_search_args(rule_conf, 'tcp', 'flags', 'not')
        if not_flags:
            duplicates = [flag for flag in tcp_flags if flag in not_flags]
            if duplicates:
                raise ConfigError(f'Cannot match a tcp flag as set and not set')

    if 'protocol' in rule_conf:
        if rule_conf['protocol'] == 'icmp' and ipv6:
            raise ConfigError(f'Cannot match IPv4 ICMP protocol on IPv6, use ipv6-icmp')
        if rule_conf['protocol'] == 'ipv6-icmp' and not ipv6:
            raise ConfigError(f'Cannot match IPv6 ICMP protocol on IPv4, use icmp')

    for side in ['destination', 'source']:
        if side in rule_conf:
            side_conf = rule_conf[side]

            if 'group' in side_conf:
                if {'address_group', 'network_group'} <= set(side_conf['group']):
                    raise ConfigError('Only one address-group or network-group can be specified')

                for group in valid_groups:
                    if group in side_conf['group']:
                        group_name = side_conf['group'][group]

                        if group_name and group_name[0] == '!':
                            group_name = group_name[1:]

                        fw_group = f'ipv6_{group}' if ipv6 and group in ['address_group', 'network_group'] else group
                        error_group = fw_group.replace("_", "-")
                        group_obj = dict_search_args(firewall, 'group', fw_group, group_name)

                        if group_obj is None:
                            raise ConfigError(f'Invalid {error_group} "{group_name}" on firewall rule')

                        if not group_obj:
                            Warning(f'{error_group} "{group_name}" has no members!')

            if 'port' in side_conf or dict_search_args(side_conf, 'group', 'port_group'):
                if 'protocol' not in rule_conf:
                    raise ConfigError('Protocol must be defined if specifying a port or port-group')

                if rule_conf['protocol'] not in ['tcp', 'udp', 'tcp_udp']:
                    raise ConfigError('Protocol must be tcp, udp, or tcp_udp when specifying a port or port-group')

def verify(firewall):
    if 'config_trap' in firewall and firewall['config_trap'] == 'enable':
        if not firewall['trap_targets']:
            raise ConfigError(f'Firewall config-trap enabled but "service snmp trap-target" is not defined')

    for name in ['name', 'ipv6_name']:
        if name in firewall:
            for name_id, name_conf in firewall[name].items():
                if name_id in preserve_chains:
                    raise ConfigError(f'Firewall name "{name_id}" is reserved for VyOS')

                if name_id.startswith("VZONE"):
                    raise ConfigError(f'Firewall name "{name_id}" uses reserved prefix')

                if 'rule' in name_conf:
                    for rule_id, rule_conf in name_conf['rule'].items():
                        verify_rule(firewall, rule_conf, name == 'ipv6_name')

    for ifname, if_firewall in firewall['interfaces'].items():
        for direction in ['in', 'out', 'local']:
            name = dict_search_args(if_firewall, direction, 'name')
            ipv6_name = dict_search_args(if_firewall, direction, 'ipv6_name')

            if name and dict_search_args(firewall, 'name', name) == None:
                raise ConfigError(f'Firewall name "{name}" is still referenced on interface {ifname}')

            if ipv6_name and dict_search_args(firewall, 'ipv6_name', ipv6_name) == None:
                raise ConfigError(f'Firewall ipv6-name "{ipv6_name}" is still referenced on interface {ifname}')

    for fw_name, used_names in firewall['zone_policy'].items():
        for name in used_names:
            if dict_search_args(firewall, fw_name, name) == None:
                raise ConfigError(f'Firewall {fw_name.replace("_", "-")} "{name}" is still referenced in zone-policy')

    return None

def cleanup_rule(table, jump_chain):
    commands = []
    chains = nft_iface_chains if table == 'ip filter' else nft6_iface_chains
    for chain in chains:
        results = cmd(f'nft -a list chain {table} {chain}').split("\n")
        for line in results:
            if f'jump {jump_chain}' in line:
                handle_search = re.search('handle (\d+)', line)
                if handle_search:
                    commands.append(f'delete rule {table} {chain} handle {handle_search[1]}')
    return commands

def cleanup_commands(firewall):
    commands = []
    commands_end = []
    for table in ['ip filter', 'ip6 filter']:
        state_chain = 'VYOS_STATE_POLICY' if table == 'ip filter' else 'VYOS_STATE_POLICY6'
        json_str = cmd(f'nft -j list table {table}')
        obj = loads(json_str)
        if 'nftables' not in obj:
            continue
        for item in obj['nftables']:
            if 'chain' in item:
                chain = item['chain']['name']
                if chain in ['VYOS_STATE_POLICY', 'VYOS_STATE_POLICY6']:
                    if 'state_policy' not in firewall:
                        commands.append(f'delete chain {table} {chain}')
                    else:
                        commands.append(f'flush chain {table} {chain}')
                elif chain not in preserve_chains and not chain.startswith("VZONE"):
                    if table == 'ip filter' and dict_search_args(firewall, 'name', chain.replace(NAME_PREFIX, "", 1)) != None:
                        commands.append(f'flush chain {table} {chain}')
                    elif table == 'ip6 filter' and dict_search_args(firewall, 'ipv6_name', chain.replace(NAME6_PREFIX, "", 1)) != None:
                        commands.append(f'flush chain {table} {chain}')
                    else:
                        commands += cleanup_rule(table, chain)
                        commands.append(f'delete chain {table} {chain}')
            elif 'rule' in item:
                rule = item['rule']
                if rule['chain'] in ['VYOS_FW_FORWARD', 'VYOS_FW_OUTPUT', 'VYOS_FW_LOCAL', 'VYOS_FW6_FORWARD', 'VYOS_FW6_OUTPUT', 'VYOS_FW6_LOCAL']:
                    if 'expr' in rule and any([True for expr in rule['expr'] if dict_search_args(expr, 'jump', 'target') == state_chain]):
                        if 'state_policy' not in firewall:
                            chain = rule['chain']
                            handle = rule['handle']
                            commands.append(f'delete rule {table} {chain} handle {handle}')
            elif 'set' in item:
                set_name = item['set']['name']
                commands_end.append(f'delete set {table} {set_name}')
    return commands + commands_end

def generate(firewall):
    if not os.path.exists(nftables_conf):
        firewall['first_install'] = True
    else:
        firewall['cleanup_commands'] = cleanup_commands(firewall)

    render(nftables_conf, 'firewall/nftables.j2', firewall)
    render(nftables_defines_conf, 'firewall/nftables-defines.j2', firewall)
    return None

def apply_sysfs(firewall):
    for name, conf in sysfs_config.items():
        paths = glob(conf['sysfs'])
        value = None

        if name in firewall:
            conf_value = firewall[name]

            if conf_value in conf:
                value = conf[conf_value]
            elif conf_value == 'enable':
                value = '1'
            elif conf_value == 'disable':
                value = '0'

        if value:
            for path in paths:
                with open(path, 'w') as f:
                    f.write(value)

def post_apply_trap(firewall):
    if 'first_install' in firewall:
        return None

    if 'config_trap' not in firewall or firewall['config_trap'] != 'enable':
        return None

    if not process_named_running('snmpd'):
        return None

    trap_username = os.getlogin()

    for host, target_conf in firewall['trap_targets'].items():
        community = target_conf['community'] if 'community' in target_conf else 'public'
        port = int(target_conf['port']) if 'port' in target_conf else 162

        base_cmd = f'snmptrap -v2c -c {community} {host}:{port} 0 {snmp_trap_mib}::{snmp_trap_name} '

        for change_type, changes in firewall['trap_diff'].items():
            for path_str, value in changes.items():
                objects = [
                    f'mgmtEventUser s "{trap_username}"',
                    f'mgmtEventSource i {snmp_event_source}',
                    f'mgmtEventType i {snmp_change_type[change_type]}'
                ]

                if change_type == 'add':
                    objects.append(f'mgmtEventCurrCfg s "{path_str} {value}"')
                elif change_type == 'delete':
                    objects.append(f'mgmtEventPrevCfg s "{path_str} {value}"')
                elif change_type == 'change':
                    objects.append(f'mgmtEventPrevCfg s "{path_str} {value[0]}"')
                    objects.append(f'mgmtEventCurrCfg s "{path_str} {value[1]}"')

                cmd(base_cmd + ' '.join(objects))

def state_policy_rule_exists():
    # Determine if state policy rules already exist in nft
    search_str = cmd(f'nft list chain ip filter VYOS_FW_FORWARD')
    return 'VYOS_STATE_POLICY' in search_str

def resync_policy_route():
    # Update policy route as firewall groups were updated
    tmp = run(policy_route_conf_script)
    if tmp > 0:
        Warning('Failed to re-apply policy route configuration!')

def apply(firewall):
    if 'first_install' in firewall:
        run('nfct helper add rpc inet tcp')
        run('nfct helper add rpc inet udp')
        run('nfct helper add tns inet tcp')

    install_result = run(f'nft -f {nftables_conf}')
    if install_result == 1:
        raise ConfigError('Failed to apply firewall')

    # set fireall group domain-group xxx
    if 'group' in firewall:
        if 'domain_group' in firewall['group']:
            # T970 Enable a resolver (systemd daemon) that checks
            # domain-group addresses and update entries for domains by timeout
            # If router loaded without internet connection or for synchronization
            call('systemctl restart vyos-domain-group-resolve.service')
            for group, group_config in firewall['group']['domain_group'].items():
                domains = []
                for address in group_config['address']:
                    domains.append(address)
                # Add elements to domain-group, try to resolve domain => ip
                # and add elements to nft set
                elements = get_ips_domains_dict(domains)
                nft_init_set(group)
                nft_add_set_elements(group, elements)
        else:
            call('systemctl stop vyos-domain-group-resolve.service')

    if 'state_policy' in firewall and not state_policy_rule_exists():
        for chain in ['VYOS_FW_FORWARD', 'VYOS_FW_OUTPUT', 'VYOS_FW_LOCAL']:
            cmd(f'nft insert rule ip filter {chain} jump VYOS_STATE_POLICY')

        for chain in ['VYOS_FW6_FORWARD', 'VYOS_FW6_OUTPUT', 'VYOS_FW6_LOCAL']:
            cmd(f'nft insert rule ip6 filter {chain} jump VYOS_STATE_POLICY6')

    apply_sysfs(firewall)

    if firewall['policy_resync']:
        resync_policy_route()

    post_apply_trap(firewall)

    return None

if __name__ == '__main__':
    try:
        c = get_config()
        verify(c)
        generate(c)
        apply(c)
    except ConfigError as e:
        print(e)
        exit(1)