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Firewall4 patch for iNAT leakage rules
From e1fac75857f5f9ee0e9461c4f16a10dcb3b5dc71 Mon Sep 17 00:00:00 2001
From: Jo-Philipp Wich <jo@mein.io>
Date: Tue, 25 Oct 2022 21:03:00 +0200
Subject: [PATCH] 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>
---
root/usr/share/firewall4/templates/ruleset.uc | 3 +
.../firewall4/templates/zone-drop-invalid.uc | 8 +
tests/01_configuration/01_ruleset | 1 +
tests/02_zones/02_masq | 1 +
tests/02_zones/03_masq_src_dest_restrictions | 1 +
tests/02_zones/04_masq_allow_invalid | 179 ++++++++++++++++++
6 files changed, 193 insertions(+)
create mode 100644 root/usr/share/firewall4/templates/zone-drop-invalid.uc
create mode 100644 tests/02_zones/04_masq_allow_invalid
diff --git a/root/usr/share/firewall4/templates/ruleset.uc b/root/usr/share/firewall4/templates/ruleset.uc
index d6333f1..d6eedfd 100644
--- 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
index 0000000..7cbb318
--- /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 }) -%}
+ctstate invalid {%+ if (zone.counter): -%}
+ counter {%+ endif -%}
+{%+ if (zone.log & 1): -%}
+ log prefix "drop {{ zone.name }} invalid ctstate: " {%+ endif -%}
+drop comment "!fw4: Prevent NAT leakage"
diff --git a/tests/01_configuration/01_ruleset b/tests/01_configuration/01_ruleset
index e30ca76..0260bfe 100644
--- 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" ctstate 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 369cdd6..ccdf147 100644
--- 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" ctstate 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 2cb0ce4..e9fc3ab 100644
--- 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" ctstate 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
index 0000000..a5b3bc6
--- /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 ctstate 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 --
--
2.35.1
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