firewall: T5080: Disable conntrack unless required by rules

4 files changed, 43 insertions, 2 deletions

diff --git a/data/templates/firewall/nftables.j2 b/data/templates/firewall/nftables.j2
index 84af0449a..0fbddfaa9 100644
--- a/data/templates/firewall/nftables.j2
+++ b/data/templates/firewall/nftables.j2
@@ -2,6 +2,21 @@
 
 {% import 'firewall/nftables-defines.j2' as group_tmpl %}
 
+flush chain raw FW_CONNTRACK
+flush chain ip6 raw FW_CONNTRACK
+
+table raw {
+    chain FW_CONNTRACK {
+        {{ ipv4_conntrack_action }}
+    }
+}
+
+table ip6 raw {
+    chain FW_CONNTRACK {
+        {{ ipv6_conntrack_action }}
+    }
+}
+
 {% if first_install is not vyos_defined %}
 delete table inet vyos_global_rpfilter
 {% endif %}
diff --git a/data/vyos-firewall-init.conf b/data/vyos-firewall-init.conf
index ab25ab4bd..41e7627f5 100644
--- a/data/vyos-firewall-init.conf
+++ b/data/vyos-firewall-init.conf
@@ -73,7 +73,7 @@ table raw {
     }
 
     chain FW_CONNTRACK {
-        accept
+        return
     }
 }
 
@@ -109,6 +109,6 @@ table ip6 raw {
     }
 
     chain FW_CONNTRACK {
-        accept
+        return
     }
 }
diff --git a/smoketest/scripts/cli/test_firewall.py b/smoketest/scripts/cli/test_firewall.py
index c6514210b..ee6ccb710 100755
--- a/smoketest/scripts/cli/test_firewall.py
+++ b/smoketest/scripts/cli/test_firewall.py
@@ -78,6 +78,17 @@ class TestFirewall(VyOSUnitTestSHIM.TestCase):
                     break
             self.assertTrue(not matched if inverse else matched, msg=search)
 
+    def verify_nftables_chain(self, nftables_search, table, chain, inverse=False, args=''):
+        nftables_output = cmd(f'sudo nft {args} list chain {table} {chain}')
+
+        for search in nftables_search:
+            matched = False
+            for line in nftables_output.split("\n"):
+                if all(item in line for item in search):
+                    matched = True
+                    break
+            self.assertTrue(not matched if inverse else matched, msg=search)
+
     def wait_for_domain_resolver(self, table, set_name, element, max_wait=10):
         # Resolver no longer blocks commit, need to wait for daemon to populate set
         count = 0
@@ -511,6 +522,10 @@ class TestFirewall(VyOSUnitTestSHIM.TestCase):
 
         self.verify_nftables(nftables_search, 'ip vyos_filter')
 
+        # Check conntrack
+        self.verify_nftables_chain([['accept']], 'raw', 'FW_CONNTRACK')
+        self.verify_nftables_chain([['return']], 'ip6 raw', 'FW_CONNTRACK')
+
     def test_source_validation(self):
         # Strict
         self.cli_set(['firewall', 'global-options', 'source-validation', 'strict'])
diff --git a/src/conf_mode/firewall.py b/src/conf_mode/firewall.py
index c86d1b555..c3b1ee015 100755
--- a/src/conf_mode/firewall.py
+++ b/src/conf_mode/firewall.py
@@ -333,6 +333,17 @@ def generate(firewall):
     if not os.path.exists(nftables_conf):
         firewall['first_install'] = True
 
+    # Determine if conntrack is needed
+    firewall['ipv4_conntrack_action'] = 'return'
+    firewall['ipv6_conntrack_action'] = 'return'
+
+    for rules, path in dict_search_recursive(firewall, 'rule'):
+        if any(('state' in rule_conf or 'connection_status' in rule_conf) for rule_conf in rules.values()):
+            if path[0] == 'ipv4':
+                firewall['ipv4_conntrack_action'] = 'accept'
+            elif path[0] == 'ipv6':
+                firewall['ipv6_conntrack_action'] = 'accept'
+
     render(nftables_conf, 'firewall/nftables.j2', firewall)
     return None