firewall: T2199: Migrate firewall to XML/Python

1 files changed, 146 insertions, 0 deletions

diff --git a/src/conf_mode/firewall-interface.py b/src/conf_mode/firewall-interface.py
new file mode 100755
index 000000000..3a17dc5a4
--- /dev/null
+++ b/src/conf_mode/firewall-interface.py
@@ -0,0 +1,146 @@
+#!/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 os
+import re
+
+from sys import argv
+from sys import exit
+
+from vyos.config import Config
+from vyos.configdict import leaf_node_changed
+from vyos.ifconfig import Section
+from vyos.template import render
+from vyos.util import cmd
+from vyos.util import dict_search_args
+from vyos.util import run
+from vyos import ConfigError
+from vyos import airbag
+airbag.enable()
+
+NFT_CHAINS = {
+    'in': 'VYOS_FW_IN',
+    'out': 'VYOS_FW_OUT',
+    'local': 'VYOS_FW_LOCAL'
+}
+NFT6_CHAINS = {
+    'in': 'VYOS_FW6_IN',
+    'out': 'VYOS_FW6_OUT',
+    'local': 'VYOS_FW6_LOCAL'
+}
+
+def get_config(config=None):
+    if config:
+        conf = config
+    else:
+        conf = Config()
+
+    ifname = argv[1]
+    ifpath = Section.get_config_path(ifname)
+    if_firewall_path = f'interfaces {ifpath} firewall'
+
+    if_firewall = conf.get_config_dict(if_firewall_path, key_mangling=('-', '_'), get_first_key=True,
+                                    no_tag_node_value_mangle=True)
+
+    if_firewall['ifname'] = ifname
+    if_firewall['firewall'] = conf.get_config_dict(['firewall'], key_mangling=('-', '_'), get_first_key=True,
+                                    no_tag_node_value_mangle=True)
+
+    return if_firewall
+
+def verify(if_firewall):
+    # bail out early - looks like removal from running config
+    if not if_firewall:
+        return None
+
+    for direction in ['in', 'out', 'local']:
+        if direction in if_firewall:
+            if 'name' in if_firewall[direction]:
+                name = if_firewall[direction]['name']
+
+                if 'name' not in if_firewall['firewall']:
+                    raise ConfigError('Firewall name not configured')
+
+                if name not in if_firewall['firewall']['name']:
+                    raise ConfigError(f'Invalid firewall name "{name}"')
+
+            if 'ipv6_name' in if_firewall[direction]:
+                name = if_firewall[direction]['ipv6_name']
+
+                if 'ipv6_name' not in if_firewall['firewall']:
+                    raise ConfigError('Firewall ipv6-name not configured')
+
+                if name not in if_firewall['firewall']['ipv6_name']:
+                    raise ConfigError(f'Invalid firewall ipv6-name "{name}"')
+
+    return None
+
+def generate(if_firewall):
+    return None
+
+def cleanup_rule(table, chain, ifname, new_name=None):
+    results = cmd(f'nft -a list chain {table} {chain}').split("\n")
+    retval = None
+    for line in results:
+        if f'ifname "{ifname}"' in line:
+            if new_name and f'jump {new_name}' in line:
+                # new_name is used to clear rules for any previously referenced chains
+                # returns true when rule exists and doesn't need to be created
+                retval = True
+                continue
+
+            handle_search = re.search('handle (\d+)', line)
+            if handle_search:
+                run(f'nft delete rule {table} {chain} handle {handle_search[1]}')
+    return retval
+
+def apply(if_firewall):
+    ifname = if_firewall['ifname']
+
+    for direction in ['in', 'out', 'local']:
+        chain = NFT_CHAINS[direction]
+        ipv6_chain = NFT6_CHAINS[direction]
+        if_prefix = 'i' if direction in ['in', 'local'] else 'o'
+
+        name = dict_search_args(if_firewall, direction, 'name')
+        if name:
+            rule_exists = cleanup_rule('ip filter', chain, ifname, name)
+
+            if not rule_exists:
+                run(f'nft insert rule ip filter {chain} {if_prefix}ifname {ifname} counter jump {name}')
+        else:
+            cleanup_rule('ip filter', chain, ifname)
+
+        ipv6_name = dict_search_args(if_firewall, direction, 'ipv6_name')
+        if ipv6_name:
+            rule_exists = cleanup_rule('ip6 filter', ipv6_chain, ifname, ipv6_name)
+
+            if not rule_exists:
+                run(f'nft insert rule ip6 filter {ipv6_chain} {if_prefix}ifname {ifname} counter jump {ipv6_name}')
+        else:
+            cleanup_rule('ip6 filter', ipv6_chain, ifname)
+
+    return None
+
+if __name__ == '__main__':
+    try:
+        c = get_config()
+        verify(c)
+        generate(c)
+        apply(c)
+    except ConfigError as e:
+        print(e)
+        exit(1)