tv: modularize iptables configuration

3 files changed, 133 insertions, 0 deletions

diff --git a/modules/tv/iptables/config.nix b/modules/tv/iptables/config.nix
new file mode 100644
index 000000000..a525cfa5d
--- /dev/null
+++ b/modules/tv/iptables/config.nix
@@ -0,0 +1,93 @@
+{ cfg, lib, pkgs, ... }:
+
+let
+  inherit (pkgs) writeScript writeText;
+  inherit (lib) concatMapStringsSep;
+
+  accept-new-tcp = port:
+    "-p tcp -m tcp --dport ${port} -m conntrack --ctstate NEW -j ACCEPT";
+
+  rules = iptables-version:
+    writeText "tv-iptables-rules${toString iptables-version}" ''
+      *nat
+      :PREROUTING ACCEPT [0:0]
+      :INPUT ACCEPT [0:0]
+      :OUTPUT ACCEPT [0:0]
+      :POSTROUTING ACCEPT [0:0]
+      ${concatMapStringsSep "\n" (rule: "-A PREROUTING ${rule}") ([]
+        ++ [
+          "! -i retiolum -p tcp -m tcp --dport 22 -j REDIRECT --to-ports 0"
+          "-p tcp -m tcp --dport 11423 -j REDIRECT --to-ports 22"
+        ]
+      )}
+      COMMIT
+      *filter
+      :INPUT DROP [0:0]
+      :FORWARD DROP [0:0]
+      :OUTPUT ACCEPT [0:0]
+      :Retiolum - [0:0]
+      ${concatMapStringsSep "\n" (rule: "-A INPUT ${rule}") ([]
+        ++ [
+          "-m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT"
+          "-i lo -j ACCEPT"
+        ]
+        ++ map accept-new-tcp cfg.input-internet-accept-new-tcp
+        ++ ["-i retiolum -j Retiolum"]
+      )}
+      ${concatMapStringsSep "\n" (rule: "-A Retiolum ${rule}") ([]
+        ++ {
+          ip4tables = [
+            "-p icmp -m icmp --icmp-type echo-request -j ACCEPT"
+          ];
+          ip6tables = [
+            "-p ipv6-icmp -m icmp6 --icmpv6-type echo-request -j ACCEPT"
+          ];
+        }."ip${toString iptables-version}tables"
+        ++ map accept-new-tcp cfg.input-retiolum-accept-new-tcp
+        ++ {
+          ip4tables = [
+            "-p tcp -j REJECT --reject-with tcp-reset"
+            "-p udp -j REJECT --reject-with icmp-port-unreachable"
+            "-j REJECT --reject-with icmp-proto-unreachable"
+          ];
+          ip6tables = [
+            "-p tcp -j REJECT --reject-with tcp-reset"
+            "-p udp -j REJECT --reject-with icmp6-port-unreachable"
+            "-j REJECT"
+          ];
+        }."ip${toString iptables-version}tables"
+      )}
+      COMMIT
+    '';
+
+  startScript = writeScript "tv-iptables_start" ''
+    #! /bin/sh
+    set -euf
+    iptables-restore < ${rules 4}
+    ip6tables-restore < ${rules 6}
+  '';
+in
+
+{
+  networking.firewall.enable = false;
+
+  systemd.services.tv-iptables = {
+    description = "tv-iptables";
+    wantedBy = [ "network-pre.target" ];
+    before = [ "network-pre.target" ];
+    after = [ "systemd-modules-load.service" ];
+
+    path = with pkgs; [
+      iptables
+    ];
+    
+    restartIfChanged = true;
+    
+    serviceConfig = {
+      Type = "simple";
+      RemainAfterExit = true;
+      Restart = "always";
+      ExecStart = "@${startScript} tv-iptables_start";
+    };
+  };
+}
diff --git a/modules/tv/iptables/default.nix b/modules/tv/iptables/default.nix
new file mode 100644
index 000000000..cf27a26ac
--- /dev/null
+++ b/modules/tv/iptables/default.nix
@@ -0,0 +1,11 @@
+arg@{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.tv.iptables;
+  arg' = arg // { inherit cfg; };
+in
+
+{
+  options.tv.iptables = import ./options.nix arg';
+  config = lib.mkIf cfg.enable (import ./config.nix arg');
+}
diff --git a/modules/tv/iptables/options.nix b/modules/tv/iptables/options.nix
new file mode 100644
index 000000000..79be1d08a
--- /dev/null
+++ b/modules/tv/iptables/options.nix
@@ -0,0 +1,29 @@
+{ lib, ... }:
+
+let
+  inherit (lib) mkOption types;
+in
+
+{
+  enable = mkOption {
+    type = types.bool;
+    default = false;
+    description = "Enable iptables.";
+  };
+
+  input-internet-accept-new-tcp = mkOption {
+    type = with types; listOf str;
+    default = [];
+    description = ''
+      ip{4,6}tables -A INPUT -j ACCEPT -p tcp --dport $port -m conntrack --ctstate NEW
+    '';
+  };
+
+  input-retiolum-accept-new-tcp = mkOption {
+    type = with types; listOf str;
+    default = [];
+    description = ''
+      ip{4,6}tables -A Retiolum -j ACCEPT -p tcp --dport $port -m conntrack --ctstate NEW
+    '';
+  };
+}