firewall: T3509: Add support for IPv6 reverse path filtering

data/templates/firewall/nftables.j2

@@ -2,6 +2,20 @@
 
 {% import 'firewall/nftables-defines.j2' as group_tmpl %}
 
+{% if first_install is not vyos_defined %}
+delete table inet vyos_global_rpfilter
+{% endif %}
+table inet vyos_global_rpfilter {
+    chain PREROUTING {
+        type filter hook prerouting priority -300; policy accept;
+{% if global_options.source_validation is vyos_defined('loose') %}
+        fib saddr oif 0 counter drop
+{% elif global_options.source_validation is vyos_defined('strict') %}
+        fib saddr . iif oif 0 counter drop
+{% endif %}
+    }
+}
+
 {% if first_install is not vyos_defined %}
 delete table ip vyos_filter
 {% endif %}

data/vyos-firewall-init.conf

@@ -82,6 +82,10 @@ table ip6 raw {
         type filter hook forward priority -300; policy accept;
     }
 
+    chain vyos_rpfilter {
+        type filter hook prerouting priority -300; policy accept;
+    }
+
     chain PREROUTING {
         type filter hook prerouting priority -300; policy accept;
         counter jump VYOS_CT_PREROUTING_HOOK

interface-definitions/include/interface/ipv6-options.xml.i

@@ -9,6 +9,7 @@
     #include <include/interface/ipv6-accept-dad.xml.i>
     #include <include/interface/ipv6-address.xml.i>
     #include <include/interface/ipv6-dup-addr-detect-transmits.xml.i>
+    #include <include/interface/source-validation.xml.i>
   </children>
 </node>
 <!-- include end -->

python/vyos/ifconfig/interface.py

@@ -777,6 +777,30 @@ def set_ipv4_source_validation(self, value):
             return None
         return self.set_interface('rp_filter', value)
 
+    def _cleanup_ipv6_source_validation_rules(self, ifname):
+        commands = []
+        results = self._cmd(f'nft -a list chain ip6 raw vyos_rpfilter').split("\n")
+        for line in results:
+            if f'iifname "{ifname}"' in line:
+                handle_search = re.search('handle (\d+)', line)
+                if handle_search:
+                    self._cmd(f'nft delete rule ip6 raw vyos_rpfilter handle {handle_search[1]}')
+
+    def set_ipv6_source_validation(self, mode):
+        """
+        Set IPv6 reverse path validation
+
+        Example:
+        >>> from vyos.ifconfig import Interface
+        >>> Interface('eth0').set_ipv6_source_validation('strict')
+        """
+        self._cleanup_ipv6_source_validation_rules(self.ifname)
+        nft_prefix = f'nft add rule ip6 raw vyos_rpfilter iifname "{self.ifname}"'
+        if mode == 'strict':
+            self._cmd(f"{nft_prefix} fib saddr . iif oif 0 counter drop")
+        elif mode == 'loose':
+            self._cmd(f"{nft_prefix} fib saddr oif 0 counter drop")
+
     def set_ipv6_accept_ra(self, accept_ra):
         """
         Accept Router Advertisements; autoconfigure using them.
@@ -1568,6 +1592,11 @@ def update(self, config):
         value = tmp if (tmp != None) else '0'
         self.set_ipv4_source_validation(value)
 
+        # IPv6 source-validation
+        tmp = dict_search('ipv6.source_validation', config)
+        value = tmp if (tmp != None) else '0'
+        self.set_ipv6_source_validation(value)
+
         # MTU - Maximum Transfer Unit has a default value. It must ALWAYS be set
         # before mangling any IPv6 option. If MTU is less then 1280 IPv6 will be
         # automatically disabled by the kernel. Also MTU must be increased before

smoketest/scripts/cli/base_interfaces_test.py

@@ -844,6 +844,7 @@ def test_interface_ipv6_options(self):
             mss = '1400'
             dad_transmits = '10'
             accept_dad = '0'
+            source_validation = 'strict'
 
             for interface in self._interfaces:
                 path = self._base_path + [interface]
@@ -863,6 +864,9 @@ def test_interface_ipv6_options(self):
                 if cli_defined(self._base_path + ['ipv6'], 'disable-forwarding'):
                     self.cli_set(path + ['ipv6', 'disable-forwarding'])
 
+                if cli_defined(self._base_path + ['ipv6'], 'source-validation'):
+                    self.cli_set(path + ['ipv6', 'source-validation', source_validation])
+
             self.cli_commit()
 
             for interface in self._interfaces:
@@ -886,6 +890,14 @@ def test_interface_ipv6_options(self):
                     tmp = read_file(f'{proc_base}/forwarding')
                     self.assertEqual('0', tmp)
 
+                if cli_defined(self._base_path + ['ipv6'], 'source-validation'):
+                    base_options = f'iifname "{interface}"'
+                    out = cmd('sudo nft list chain ip6 raw vyos_rpfilter')
+                    for line in out.splitlines():
+                        if line.startswith(base_options):
+                            self.assertIn('fib saddr . iif oif 0', line)
+                            self.assertIn('drop', line)
+
         def test_dhcpv6_client_options(self):
             if not self._test_ipv6_dhcpc6:
                 self.skipTest('not supported')

smoketest/scripts/cli/test_firewall.py

@@ -511,6 +511,27 @@ def test_ipv4_state_and_status_rules(self):
 
         self.verify_nftables(nftables_search, 'ip vyos_filter')
 
+    def test_source_validation(self):
+        # Strict
+        self.cli_set(['firewall', 'global-options', 'source-validation', 'strict'])
+        self.cli_commit()
+
+        nftables_strict_search = [
+            ['fib saddr . iif oif 0', 'drop']
+        ]
+
+        self.verify_nftables(nftables_strict_search, 'inet vyos_global_rpfilter')
+
+        # Loose
+        self.cli_set(['firewall', 'global-options', 'source-validation', 'loose'])
+        self.cli_commit()
+
+        nftables_loose_search = [
+            ['fib saddr oif 0', 'drop']
+        ]
+
+        self.verify_nftables(nftables_loose_search, 'inet vyos_global_rpfilter')
+
     def test_sysfs(self):
         for name, conf in sysfs_config.items():
             paths = glob(conf['sysfs'])

src/conf_mode/firewall.py

@@ -54,7 +54,6 @@
     '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'}
 }