firewall: T2199: Migrate firewall to XML/Python

4 files changed, 269 insertions, 26 deletions

diff --git a/python/vyos/configdiff.py b/python/vyos/configdiff.py
index 0e41fbe27..4ad7443d7 100644
--- a/python/vyos/configdiff.py
+++ b/python/vyos/configdiff.py
@@ -17,7 +17,9 @@ from enum import IntFlag, auto
 
 from vyos.config import Config
 from vyos.configdict import dict_merge
+from vyos.configdict import list_diff
 from vyos.util import get_sub_dict, mangle_dict_keys
+from vyos.util import dict_search_args
 from vyos.xml import defaults
 
 class ConfigDiffError(Exception):
@@ -134,6 +136,34 @@ class ConfigDiff(object):
                                                     self._key_mangling[1])
         return config_dict
 
+    def get_child_nodes_diff_str(self, path=[]):
+        ret = {'add': {}, 'change': {}, 'delete': {}}
+
+        diff = self.get_child_nodes_diff(path,
+                                expand_nodes=Diff.ADD | Diff.DELETE | Diff.MERGE | Diff.STABLE,
+                                no_defaults=True)
+
+        def parse_dict(diff_dict, diff_type, prefix=[]):
+            for k, v in diff_dict.items():
+                if isinstance(v, dict):
+                    parse_dict(v, diff_type, prefix + [k])
+                else:
+                    path_str = ' '.join(prefix + [k])
+                    if diff_type == 'add' or diff_type == 'delete':
+                        if isinstance(v, list):
+                            v = ', '.join(v)
+                        ret[diff_type][path_str] = v
+                    elif diff_type == 'merge':
+                        old_value = dict_search_args(diff['stable'], *prefix, k)
+                        if old_value and old_value != v:
+                            ret['change'][path_str] = [old_value, v]
+
+        parse_dict(diff['merge'], 'merge')
+        parse_dict(diff['add'], 'add')
+        parse_dict(diff['delete'], 'delete')
+
+        return ret
+
     def get_child_nodes_diff(self, path=[], expand_nodes=Diff(0), no_defaults=False):
         """
         Args:
diff --git a/python/vyos/firewall.py b/python/vyos/firewall.py
new file mode 100644
index 000000000..9b8af7852
--- /dev/null
+++ b/python/vyos/firewall.py
@@ -0,0 +1,194 @@
+#!/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'])
+        output.append(f'ct state {{{states}}}')
+
+    if 'protocol' in rule_conf and rule_conf['protocol'] != 'all':
+        proto = rule_conf['protocol']
+        if proto == 'tcp_udp':
+            proto = '{tcp, udp}'
+        output.append('meta l4proto ' + proto)
+
+    for side in ['destination', 'source']:
+        if side in rule_conf:
+            prefix = side[0]
+            side_conf = rule_conf[side]
+
+            if 'address' in side_conf:
+                output.append(f'{ip_name} {prefix}addr {side_conf["address"]}')
+
+            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"]
+
+                if isinstance(port, list):
+                    port = ",".join(port)
+
+                if proto == 'tcp_udp':
+                    proto = 'th'
+
+                output.append(f'{proto} {prefix}port {{{port}}}')
+
+            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 '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)
diff --git a/python/vyos/ifconfig/interface.py b/python/vyos/ifconfig/interface.py
index 58d130ef6..edc99d6f7 100755
--- a/python/vyos/ifconfig/interface.py
+++ b/python/vyos/ifconfig/interface.py
@@ -544,6 +544,15 @@ class Interface(Control):
             return None
         return self.set_interface('arp_cache_tmo', tmo)
 
+    def _cleanup_mss_rules(self, table, ifname):
+        commands = []
+        results = self._cmd(f'nft -a list chain {table} VYOS_TCP_MSS').split("\n")
+        for line in results:
+            if f'oifname "{ifname}"' in line:
+                handle_search = re.search('handle (\d+)', line)
+                if handle_search:
+                    self._cmd(f'nft delete rule {table} VYOS_TCP_MSS handle {handle_search[1]}')
+
     def set_tcp_ipv4_mss(self, mss):
         """
         Set IPv4 TCP MSS value advertised when TCP SYN packets leave this
@@ -555,22 +564,14 @@ class Interface(Control):
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').set_tcp_ipv4_mss(1340)
         """
-        iptables_bin = 'iptables'
-        base_options = f'-A FORWARD -o {self.ifname} -p tcp -m tcp --tcp-flags SYN,RST SYN'
-        out = self._cmd(f'{iptables_bin}-save -t mangle')
-        for line in out.splitlines():
-            if line.startswith(base_options):
-                # remove OLD MSS mangling configuration
-                line = line.replace('-A FORWARD', '-D FORWARD')
-                self._cmd(f'{iptables_bin} -t mangle {line}')
-
-        cmd_mss = f'{iptables_bin} -t mangle {base_options} --jump TCPMSS'
+        self._cleanup_mss_rules('raw', self.ifname)
+        nft_prefix = 'nft add rule raw VYOS_TCP_MSS'
+        base_cmd = f'oifname "{self.ifname}" tcp flags & (syn|rst) == syn'
         if mss == 'clamp-mss-to-pmtu':
-            self._cmd(f'{cmd_mss} --clamp-mss-to-pmtu')
+            self._cmd(f"{nft_prefix} '{base_cmd} tcp option maxseg size set rt mtu'")
         elif int(mss) > 0:
-            # probably add option to clamp only if bigger:
             low_mss = str(int(mss) + 1)
-            self._cmd(f'{cmd_mss} -m tcpmss --mss {low_mss}:65535 --set-mss {mss}')
+            self._cmd(f"{nft_prefix} '{base_cmd} tcp option maxseg size {low_mss}-65535 tcp option maxseg size set {mss}'")
 
     def set_tcp_ipv6_mss(self, mss):
         """
@@ -583,22 +584,14 @@ class Interface(Control):
         >>> from vyos.ifconfig import Interface
         >>> Interface('eth0').set_tcp_mss(1320)
         """
-        iptables_bin = 'ip6tables'
-        base_options = f'-A FORWARD -o {self.ifname} -p tcp -m tcp --tcp-flags SYN,RST SYN'
-        out = self._cmd(f'{iptables_bin}-save -t mangle')
-        for line in out.splitlines():
-            if line.startswith(base_options):
-                # remove OLD MSS mangling configuration
-                line = line.replace('-A FORWARD', '-D FORWARD')
-                self._cmd(f'{iptables_bin} -t mangle {line}')
-
-        cmd_mss = f'{iptables_bin} -t mangle {base_options} --jump TCPMSS'
+        self._cleanup_mss_rules('ip6 raw', self.ifname)
+        nft_prefix = 'nft add rule ip6 raw VYOS_TCP_MSS'
+        base_cmd = f'oifname "{self.ifname}" tcp flags & (syn|rst) == syn'
         if mss == 'clamp-mss-to-pmtu':
-            self._cmd(f'{cmd_mss} --clamp-mss-to-pmtu')
+            self._cmd(f"{nft_prefix} '{base_cmd} tcp option maxseg size set rt mtu'")
         elif int(mss) > 0:
-            # probably add option to clamp only if bigger:
             low_mss = str(int(mss) + 1)
-            self._cmd(f'{cmd_mss} -m tcpmss --mss {low_mss}:65535 --set-mss {mss}')
+            self._cmd(f"{nft_prefix} '{base_cmd} tcp option maxseg size {low_mss}-65535 tcp option maxseg size set {mss}'")
 
     def set_arp_filter(self, arp_filter):
         """
diff --git a/python/vyos/template.py b/python/vyos/template.py
index b32cafe74..55bd04136 100644
--- a/python/vyos/template.py
+++ b/python/vyos/template.py
@@ -22,6 +22,7 @@ from jinja2 import FileSystemLoader
 from vyos.defaults import directories
 from vyos.util import chmod
 from vyos.util import chown
+from vyos.util import dict_search_args
 from vyos.util import makedir
 
 # Holds template filters registered via register_filter()
@@ -479,3 +480,28 @@ def get_openvpn_ncp_ciphers(ciphers):
         else:
             out.append(cipher)
     return ':'.join(out).upper()
+
+@register_filter('nft_action')
+def nft_action(vyos_action):
+    if vyos_action == 'accept':
+        return 'return'
+    return vyos_action
+
+@register_filter('nft_rule')
+def nft_rule(rule_conf, fw_name, rule_id, ip_name='ip'):
+    from vyos.firewall import parse_rule
+    return parse_rule(rule_conf, fw_name, rule_id, ip_name)
+
+@register_filter('nft_state_policy')
+def nft_state_policy(conf, state):
+    out = [f'ct state {state}']
+
+    if 'log' in conf and 'enable' in conf['log']:
+        out.append('log')
+
+    out.append('counter')
+
+    if 'action' in conf:
+        out.append(conf['action'])
+
+    return " ".join(out)