ruleset: drop ctstate invalid traffic for masq-enabled zones

For NAT enabled zones, stage rules to drop forwarded traffic with conntrack
state "invalid" and honor `masq_allow_invalid` option to inhibit those
rules.

This ports the corresponding firewall3 logic to firewall4.

Ref: https://forum.openwrt.org/t/x/140790
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

diff --git a/root/usr/share/firewall4/templates/ruleset.uc b/root/usr/share/firewall4/templates/ruleset.uc
index d6333f18188dbb7224e21dd4199ad7442b78c9f2..d6eedfd55d599b7982cfab2bd1f93ddfc9dca50e 100644 (file)
--- a/root/usr/share/firewall4/templates/ruleset.uc
+++ b/root/usr/share/firewall4/templates/ruleset.uc
@@ -265,6 +265,9 @@ table inet fw4 {
 {%   if (zone.dflags[verdict]): %}
        chain {{ verdict }}_to_{{ zone.name }} {
 {%   for (let rule in zone.match_rules): %}
+{%     if (verdict == "accept" && (zone.masq || zone.masq6) && !zone.masq_allow_invalid): %}
+               {%+ include("zone-drop-invalid.uc", { fw4, zone, rule }) %}
+{%     endif %}
                {%+ include("zone-verdict.uc", { fw4, zone, rule, egress: true, verdict }) %}
 {%   endfor %}
        }

diff --git a/root/usr/share/firewall4/templates/zone-drop-invalid.uc b/root/usr/share/firewall4/templates/zone-drop-invalid.uc
new file mode 100644 (file)
index 0000000..d16bc0b
--- /dev/null
+++ b/root/usr/share/firewall4/templates/zone-drop-invalid.uc
@@ -0,0 +1,8 @@
+{%+ if (zone.masq ^ zone.masq6): -%}
+       meta nfproto {{ fw4.nfproto(zone.masq ? 4 : 6) }} {%+ endif -%}
+{%+  include("zone-match.uc", { egress: true, rule }) -%}
+ct state invalid {%+ if (zone.counter): -%}
+       counter {%+ endif -%}
+{%+ if (zone.log & 1): -%}
+       log prefix "drop {{ zone.name }} invalid ct state: " {%+ endif -%}
+drop comment "!fw4: Prevent NAT leakage"

diff --git a/tests/01_configuration/01_ruleset b/tests/01_configuration/01_ruleset
index e30ca76b3bb22666d173aedf6dc9b7e651331d90..c4fd5b48bdff32fe0bae205bdd5962619a26d590 100644 (file)
--- a/tests/01_configuration/01_ruleset
+++ b/tests/01_configuration/01_ruleset
@@ -213,6 +213,7 @@ table inet fw4 {
        }
 
        chain accept_to_wan {
+               meta nfproto ipv4 oifname "pppoe-wan" ct state invalid counter drop comment "!fw4: Prevent NAT leakage"
                oifname "pppoe-wan" counter accept comment "!fw4: accept wan IPv4/IPv6 traffic"
        }
 

diff --git a/tests/02_zones/02_masq b/tests/02_zones/02_masq
index 369cdd60a23680072402054c3b11c6bb37549702..1b1098f1082fc4797f2900884e3a4dbcd5ce6f69 100644 (file)
--- a/tests/02_zones/02_masq
+++ b/tests/02_zones/02_masq
@@ -151,6 +151,7 @@ table inet fw4 {
        }
 
        chain accept_to_test1 {
+               meta nfproto ipv4 oifname "zone1" ct state invalid counter drop comment "!fw4: Prevent NAT leakage"
                oifname "zone1" counter accept comment "!fw4: accept test1 IPv4/IPv6 traffic"
        }
 

diff --git a/tests/02_zones/03_masq_src_dest_restrictions b/tests/02_zones/03_masq_src_dest_restrictions
index 2cb0ce459f6365c949c6a58947d75ad4f5772832..011ef8912adea405c77bd18675c5760c2d8e1e23 100644 (file)
--- a/tests/02_zones/03_masq_src_dest_restrictions
+++ b/tests/02_zones/03_masq_src_dest_restrictions
@@ -171,6 +171,7 @@ table inet fw4 {
        }
 
        chain accept_to_test1 {
+               meta nfproto ipv4 oifname "zone1" ct state invalid counter drop comment "!fw4: Prevent NAT leakage"
                oifname "zone1" counter accept comment "!fw4: accept test1 IPv4/IPv6 traffic"
        }
 

diff --git a/tests/02_zones/04_masq_allow_invalid b/tests/02_zones/04_masq_allow_invalid
new file mode 100644 (file)
index 0000000..5a404b9
--- /dev/null
+++ b/tests/02_zones/04_masq_allow_invalid
@@ -0,0 +1,179 @@
+Testing that dropping of invalid conntrack state traffic can be inhibited.
+
+-- Testcase --
+{%
+       include("./root/usr/share/firewall4/main.uc", {
+               getenv: function(varname) {
+                       switch (varname) {
+                       case 'ACTION':
+                               return 'print';
+                       }
+               }
+       })
+%}
+-- End --
+
+-- File uci/helpers.json --
+{}
+-- End --
+
+-- File fs/open~_sys_class_net_zone1_flags.txt --
+0x1103
+-- End --
+
+-- File fs/open~_sys_class_net_zone2_flags.txt --
+0x1103
+-- End --
+
+-- File uci/firewall.json --
+{
+       "zone": [
+               {
+                       ".description": "No ct state invalid drop rule should be generated",
+                       "name": "test1",
+                       "input": "ACCEPT",
+                       "output": "ACCEPT",
+                       "forward": "ACCEPT",
+                       "device": "zone1",
+                       "masq": "1",
+                       "masq_allow_invalid": 1
+               }
+       ]
+}
+-- End --
+
+-- Expect stdout --
+table inet fw4
+flush table inet fw4
+
+table inet fw4 {
+       #
+       # Defines
+       #
+
+       define test1_devices = { "zone1" }
+       define test1_subnets = {  }
+
+
+       #
+       # User includes
+       #
+
+       include "/etc/nftables.d/*.nft"
+
+
+       #
+       # Filter rules
+       #
+
+       chain input {
+               type filter hook input priority filter; policy drop;
+
+               iifname "lo" accept comment "!fw4: Accept traffic from loopback"
+
+               ct state established,related accept comment "!fw4: Allow inbound established and related flows"
+               iifname "zone1" jump input_test1 comment "!fw4: Handle test1 IPv4/IPv6 input traffic"
+       }
+
+       chain forward {
+               type filter hook forward priority filter; policy drop;
+
+               ct state established,related accept comment "!fw4: Allow forwarded established and related flows"
+               iifname "zone1" jump forward_test1 comment "!fw4: Handle test1 IPv4/IPv6 forward traffic"
+       }
+
+       chain output {
+               type filter hook output priority filter; policy drop;
+
+               oifname "lo" accept comment "!fw4: Accept traffic towards loopback"
+
+               ct state established,related accept comment "!fw4: Allow outbound established and related flows"
+               oifname "zone1" jump output_test1 comment "!fw4: Handle test1 IPv4/IPv6 output traffic"
+       }
+
+       chain prerouting {
+               type filter hook prerouting priority filter; policy accept;
+       }
+
+       chain handle_reject {
+               meta l4proto tcp reject with tcp reset comment "!fw4: Reject TCP traffic"
+               reject with icmpx type port-unreachable comment "!fw4: Reject any other traffic"
+       }
+
+       chain input_test1 {
+               jump accept_from_test1
+       }
+
+       chain output_test1 {
+               jump accept_to_test1
+       }
+
+       chain forward_test1 {
+               jump accept_to_test1
+       }
+
+       chain accept_from_test1 {
+               iifname "zone1" counter accept comment "!fw4: accept test1 IPv4/IPv6 traffic"
+       }
+
+       chain accept_to_test1 {
+               oifname "zone1" counter accept comment "!fw4: accept test1 IPv4/IPv6 traffic"
+       }
+
+
+       #
+       # NAT rules
+       #
+
+       chain dstnat {
+               type nat hook prerouting priority dstnat; policy accept;
+       }
+
+       chain srcnat {
+               type nat hook postrouting priority srcnat; policy accept;
+               oifname "zone1" jump srcnat_test1 comment "!fw4: Handle test1 IPv4/IPv6 srcnat traffic"
+       }
+
+       chain srcnat_test1 {
+               meta nfproto ipv4 masquerade comment "!fw4: Masquerade IPv4 test1 traffic"
+       }
+
+
+       #
+       # Raw rules (notrack)
+       #
+
+       chain raw_prerouting {
+               type filter hook prerouting priority raw; policy accept;
+       }
+
+       chain raw_output {
+               type filter hook output priority raw; policy accept;
+       }
+
+
+       #
+       # Mangle rules
+       #
+
+       chain mangle_prerouting {
+               type filter hook prerouting priority mangle; policy accept;
+       }
+
+       chain mangle_postrouting {
+               type filter hook postrouting priority mangle; policy accept;
+       }
+
+       chain mangle_input {
+               type filter hook input priority mangle; policy accept;
+       }
+
+       chain mangle_output {
+               type route hook output priority mangle; policy accept;
+       }
+
+       chain mangle_forward {
+               type filter hook forward priority mangle; policy accept;
+       }
+}
+-- End --