summaryrefslogtreecommitdiff
path: root/python/vyos/firewall.py
blob: 66dc8bc40da4fcfb0cf44e9f3067410e5fba21c5 (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
#!/usr/bin/env python3
#
# Copyright (C) 2021 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 re

from vyos.util import cmd
from vyos.util import dict_search_args

def find_nftables_rule(table, chain, rule_matches=[]):
    # Find rule in table/chain that matches all criteria and return the handle
    results = cmd(f'sudo nft -a list chain {table} {chain}').split("\n")
    for line in results:
        if all(rule_match in line for rule_match in rule_matches):
            handle_search = re.search('handle (\d+)', line)
            if handle_search:
                return handle_search[1]
    return None

def remove_nftables_rule(table, chain, handle):
    cmd(f'sudo nft delete rule {table} {chain} handle {handle}')

# Functions below used by template generation

def nft_action(vyos_action):
    if vyos_action == 'accept':
        return 'return'
    return vyos_action

def parse_rule(rule_conf, fw_name, rule_id, ip_name):
    output = []
    def_suffix = '6' if ip_name == 'ip6' else ''

    if 'state' in rule_conf and rule_conf['state']:
        states = ",".join([s for s, v in rule_conf['state'].items() if v == 'enable'])

        if states:
            output.append(f'ct state {{{states}}}')

    if 'protocol' in rule_conf and rule_conf['protocol'] != 'all':
        proto = rule_conf['protocol']
        operator = ''
        if proto[0] == '!':
            operator = '!='
            proto = proto[1:]
        if proto == 'tcp_udp':
            proto = '{tcp, udp}'
        output.append(f'meta l4proto {operator} {proto}')

    for side in ['destination', 'source']:
        if side in rule_conf:
            prefix = side[0]
            side_conf = rule_conf[side]

            if 'address' in side_conf:
                suffix = side_conf['address']
                if suffix[0] == '!':
                    suffix = f'!= {suffix[1:]}'
                output.append(f'{ip_name} {prefix}addr {suffix}')

            if 'mac_address' in side_conf:
                suffix = side_conf["mac_address"]
                if suffix[0] == '!':
                    suffix = f'!= {suffix[1:]}'
                output.append(f'ether {prefix}addr {suffix}')

            if 'port' in side_conf:
                proto = rule_conf['protocol']
                port = side_conf['port'].split(',')

                ports = []
                negated_ports = []

                for p in port:
                    if p[0] == '!':
                        negated_ports.append(p[1:])
                    else:
                        ports.append(p)

                if proto == 'tcp_udp':
                    proto = 'th'

                if ports:
                    ports_str = ','.join(ports)
                    output.append(f'{proto} {prefix}port {{{ports_str}}}')

                if negated_ports:
                    negated_ports_str = ','.join(negated_ports)
                    output.append(f'{proto} {prefix}port != {{{negated_ports_str}}}')

            if 'group' in side_conf:
                group = side_conf['group']
                if 'address_group' in group:
                    group_name = group['address_group']
                    output.append(f'{ip_name} {prefix}addr $A{def_suffix}_{group_name}')
                elif 'network_group' in group:
                    group_name = group['network_group']
                    output.append(f'{ip_name} {prefix}addr $N{def_suffix}_{group_name}')
                if 'port_group' in group:
                    proto = rule_conf['protocol']
                    group_name = group['port_group']

                    if proto == 'tcp_udp':
                        proto = 'th'

                    output.append(f'{proto} {prefix}port $P_{group_name}')

    if 'log' in rule_conf and rule_conf['log'] == 'enable':
        output.append('log')

    if 'hop_limit' in rule_conf:
        operators = {'eq': '==', 'gt': '>', 'lt': '<'}
        for op, operator in operators.items():
            if op in rule_conf['hop_limit']:
                value = rule_conf['hop_limit'][op]
                output.append(f'ip6 hoplimit {operator} {value}')

    for icmp in ['icmp', 'icmpv6']:
        if icmp in rule_conf:
            if 'type_name' in rule_conf[icmp]:
                output.append(icmp + ' type ' + rule_conf[icmp]['type_name'])
            else:
                if 'code' in rule_conf[icmp]:
                    output.append(icmp + ' code ' + rule_conf[icmp]['code'])
                if 'type' in rule_conf[icmp]:
                    output.append(icmp + ' type ' + rule_conf[icmp]['type'])

    if 'ipsec' in rule_conf:
        if 'match_ipsec' in rule_conf['ipsec']:
            output.append('meta ipsec == 1')
        if 'match_non_ipsec' in rule_conf['ipsec']:
            output.append('meta ipsec == 0')

    if 'fragment' in rule_conf:
        # Checking for fragmentation after priority -400 is not possible,
        # so we use a priority -450 hook to set a mark
        if 'match_frag' in rule_conf['fragment']:
            output.append('meta mark 0xffff1')
        if 'match_non_frag' in rule_conf['fragment']:
            output.append('meta mark != 0xffff1')

    if 'limit' in rule_conf:
        if 'rate' in rule_conf['limit']:
            output.append(f'limit rate {rule_conf["limit"]["rate"]}/second')
            if 'burst' in rule_conf['limit']:
                output.append(f'burst {rule_conf["limit"]["burst"]} packets')

    if 'recent' in rule_conf:
        count = rule_conf['recent']['count']
        time = rule_conf['recent']['time']
        # output.append(f'meter {fw_name}_{rule_id} {{ ip saddr and 255.255.255.255 limit rate over {count}/{time} burst {count} packets }}')
        # Waiting on input from nftables developers due to
        # bug with above line and atomic chain flushing.

    if 'time' in rule_conf:
        output.append(parse_time(rule_conf['time']))

    tcp_flags = dict_search_args(rule_conf, 'tcp', 'flags')
    if tcp_flags:
        output.append(parse_tcp_flags(tcp_flags))


    output.append('counter')

    if 'set' in rule_conf:
        output.append(parse_policy_set(rule_conf['set'], def_suffix))

    if 'action' in rule_conf:
        output.append(nft_action(rule_conf['action']))
    else:
        output.append('return')

    output.append(f'comment "{fw_name}-{rule_id}"')
    return " ".join(output)

def parse_tcp_flags(flags):
    all_flags = []
    include = []
    for flag in flags.split(","):
        if flag[0] == '!':
            flag = flag[1:]
        else:
            include.append(flag)
        all_flags.append(flag)
    return f'tcp flags & ({"|".join(all_flags)}) == {"|".join(include)}'

def parse_time(time):
    out = []
    if 'startdate' in time:
        start = time['startdate']
        if 'T' not in start and 'starttime' in time:
            start += f' {time["starttime"]}'
        out.append(f'time >= "{start}"')
    if 'starttime' in time and 'startdate' not in time:
        out.append(f'hour >= "{time["starttime"]}"')
    if 'stopdate' in time:
        stop = time['stopdate']
        if 'T' not in stop and 'stoptime' in time:
            stop += f' {time["stoptime"]}'
        out.append(f'time < "{stop}"')
    if 'stoptime' in time and 'stopdate' not in time:
        out.append(f'hour < "{time["stoptime"]}"')
    if 'weekdays' in time:
        days = time['weekdays'].split(",")
        out_days = [f'"{day}"' for day in days if day[0] != '!']
        out.append(f'day {{{",".join(out_days)}}}')
    return " ".join(out)

def parse_policy_set(set_conf, def_suffix):
    out = []
    if 'dscp' in set_conf:
        dscp = set_conf['dscp']
        out.append(f'ip{def_suffix} dscp set {dscp}')
    if 'mark' in set_conf:
        mark = set_conf['mark']
        out.append(f'meta mark set {mark}')
    if 'table' in set_conf:
        table = set_conf['table']
        if table == 'main':
            table = '254'
        mark = 0x7FFFFFFF - int(table)
        out.append(f'meta mark set {mark}')
    if 'tcp_mss' in set_conf:
        mss = set_conf['tcp_mss']
        out.append(f'tcp option maxseg size set {mss}')
    return " ".join(out)