From 7b1c2cb41d83a5d29f127a91a26f226e56e87a90 Mon Sep 17 00:00:00 2001
From: Timotej Lazar <timotej.lazar@fri.uni-lj.si>
Date: Sat, 9 Nov 2024 20:06:58 +0100
Subject: [PATCH] dnsmasq: drop dhcp-proxy option

Instead add firewall rules to allow direct communication from client networks.
---
 roles/dnsmasq/tasks/main.yml               |  6 ++++++
 roles/dnsmasq/templates/00-options.conf.j2 |  1 -
 roles/dnsmasq/templates/dnsmasq.nft.j2     | 12 ++++++++++++
 3 files changed, 18 insertions(+), 1 deletion(-)
 create mode 100644 roles/dnsmasq/templates/dnsmasq.nft.j2

diff --git a/roles/dnsmasq/tasks/main.yml b/roles/dnsmasq/tasks/main.yml
index 81a8c66..6cfcb84 100644
--- a/roles/dnsmasq/tasks/main.yml
+++ b/roles/dnsmasq/tasks/main.yml
@@ -38,4 +38,10 @@
   - 10-ranges.conf
   notify: restart dnsmasq
 
+- name: Configure nftables
+  template:
+    dest: '/etc/nftables.d/dnsmasq.nft'
+    src: 'dnsmasq.nft.j2'
+  notify: reload nftables
+
 # TODO netboot config
diff --git a/roles/dnsmasq/templates/00-options.conf.j2 b/roles/dnsmasq/templates/00-options.conf.j2
index 6e507e7..8c15522 100644
--- a/roles/dnsmasq/templates/00-options.conf.j2
+++ b/roles/dnsmasq/templates/00-options.conf.j2
@@ -5,7 +5,6 @@ bind-interfaces
 interface = {{ interfaces | map(attribute='name') | join(',') }}
 
 dhcp-authoritative
-dhcp-proxy
 
 dhcp-option = option:dns-server,{{ dns | join(',') }}
 dhcp-option = option:ntp-server,{{ ntp | join(',') }}
diff --git a/roles/dnsmasq/templates/dnsmasq.nft.j2 b/roles/dnsmasq/templates/dnsmasq.nft.j2
new file mode 100644
index 0000000..1005cfb
--- /dev/null
+++ b/roles/dnsmasq/templates/dnsmasq.nft.j2
@@ -0,0 +1,12 @@
+table inet filter {
+    chain input {
+        # networks using this DHCP server
+        ip saddr {
+{% for prefix in prefixes | selectattr('custom_fields.dhcp_server') | sort(attribute='vlan.name') %}
+{% if prefix.custom_fields.dhcp_server.address | ipaddr('address') == primary_ip4 %}
+            {{ prefix.prefix }},
+{% endif %}
+{% endfor %}
+        } udp dport { 67 } ct state new accept
+    }
+}