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# Copyright VyOS maintainers and contributors <maintainers@vyos.io>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library 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 this library. If not, see <http://www.gnu.org/licenses/>.
# T7366: Firewall rules allow empty nodes
# When configuring the firewall, many nodes are accepted with empty values,
# which are not parsed into rules.
# Very few of these have subsequent error handling. Some should be obvious
# to the user that a value is required, like 'inbound-interface' (though
# an error should still be thrown if they're configured without children).
# But some could be misunderstood and lead to an outage or wide open firewall.
# For instance, let's say someone wanted to block all icmp. They may incorrectly
# configure:
# set firewall ipv4 input filter rule 10 action drop
# set firewall ipv4 input filter rule 10 icmp
# And this would create this rule in nftables, dropping all traffic in subsequent rules:
# counter packets 0 bytes 0 drop comment "ipv4-INP-filter-10"
# They could also unintentionally allow all traffic by attempting to only allow icmp in a rule.
import json
from vyos.configtree import ConfigTree
from vyos.utils.dict import dict_search_args
firewall_base = ['firewall']
def migrate(config: ConfigTree) -> None:
if not config.exists(firewall_base):
# Nothing to do
return
firewall_dict = json.loads(config.to_json()).get('firewall')
is_empty_list = []
is_empty_list.append([
['add-address-to-group'],
['connection-status'],
['destination', 'group'],
['destination', 'geoip'],
['destination'],
['fragment'],
['gre', 'flags'],
['gre'],
['hop-limit'],
['icmp'],
['icmpv6'],
['inbound-interface'],
['ipsec'],
['limit'],
['log-options'],
['outbound-interface'],
['set'],
['source', 'group'],
['source', 'geoip'],
['source'],
['tcp', 'flags'],
['tcp'],
['time'],
['ttl'],
['vlan']
])
for family in ['ipv4', 'ipv6', 'bridge']:
if family in firewall_dict:
for chain in ['name','forward','input','output', 'prerouting']:
if chain in firewall_dict[family]:
for priority, priority_conf in firewall_dict[family][chain].items():
if 'rule' in priority_conf:
for rule_id, rule_conf in priority_conf['rule'].items():
node_deleted_list = []
for node in is_empty_list[0]:
if dict_search_args(rule_conf, *node) == {}:
if len(node) == 1:
if node not in node_deleted_list:
config.delete(firewall_base + [family, chain, priority, 'rule', rule_id, node[0]])
else:
del firewall_dict[family][chain][priority]['rule'][rule_id][node[0]][node[1]]
if dict_search_args(rule_conf, node[0]) == {}:
config.delete(firewall_base + [family, chain, priority, 'rule', rule_id, node[0]])
node_deleted_list.append([node[0]])
else:
config.delete(firewall_base + [family, chain, priority, 'rule', rule_id, node[0], node[1]])
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