nixos/opensnitch: Add options to configure daemon

nixos/modules/services/security/opensnitch.nix

@@ -3,22 +3,123 @@
 with lib;
 
 let
-  name = "opensnitch";
   cfg = config.services.opensnitch;
+  format = pkgs.formats.json {};
 in {
   options = {
     services.opensnitch = {
       enable = mkEnableOption "Opensnitch application firewall";
+      settings = mkOption {
+        type = types.submodule {
+          freeformType = format.type;
+
+          options = {
+            Server = {
+
+              Address = mkOption {
+                type = types.str;
+                description = ''
+                  Unix socket path (unix:///tmp/osui.sock, the "unix:///" part is
+                  mandatory) or TCP socket (192.168.1.100:50051).
+                '';
+              };
+
+              LogFile = mkOption {
+                type = types.path;
+                description = ''
+                  File to write logs to (use /dev/stdout to write logs to standard
+                  output).
+                '';
+              };
+
+            };
+
+            DefaultAction = mkOption {
+              type = types.enum [ "allow" "deny" ];
+              description = ''
+                Default action whether to block or allow application internet
+                access.
+              '';
+            };
+
+            DefaultDuration = mkOption {
+              type = types.enum [
+                "once" "always" "until restart" "30s" "5m" "15m" "30m" "1h"
+              ];
+              description = ''
+                Default duration of firewall rule.
+              '';
+            };
+
+            InterceptUnknown = mkOption {
+              type = types.bool;
+              description = ''
+                Wheter to intercept spare connections.
+              '';
+            };
+
+            ProcMonitorMethod = mkOption {
+              type = types.enum [ "ebpf" "proc" "ftrace" "audit" ];
+              description = ''
+                Which process monitoring method to use.
+              '';
+            };
+
+            LogLevel = mkOption {
+              type = types.enum [ 0 1 2 3 4 ];
+              description = ''
+                Default log level from 0 to 4 (debug, info, important, warning,
+                error).
+              '';
+            };
+
+            Firewall = mkOption {
+              type = types.enum [ "iptables" "nftables" ];
+              description = ''
+                Which firewall backend to use.
+              '';
+            };
+
+            Stats = {
+
+              MaxEvents = mkOption {
+                type = types.int;
+                description = ''
+                  Max events to send to the GUI.
+                '';
+              };
+
+              MaxStats = mkOption {
+                type = types.int;
+                description = ''
+                  Max stats per item to keep in backlog.
+                '';
+              };
+
+            };
+          };
+        };
+        description = ''
+          opensnitchd configuration. Refer to
+          <link xlink:href="https://github.com/evilsocket/opensnitch/wiki/Configurations"/>
+          for details on supported values.
+        '';
+      };
     };
   };
 
   config = mkIf cfg.enable {
 
+    # pkg.opensnitch is referred to elsewhere in the module so we don't need to worry about it being garbage collected
+    services.opensnitch.settings = mapAttrs (_: v: mkDefault v) (builtins.fromJSON (builtins.unsafeDiscardStringContext (builtins.readFile "${pkgs.opensnitch}/etc/default-config.json")));
+
     systemd = {
       packages = [ pkgs.opensnitch ];
       services.opensnitchd.wantedBy = [ "multi-user.target" ];
     };
 
+    environment.etc."opensnitchd/default-config.json".source = format.generate "default-config.json" cfg.settings;
+
   };
 }
 

pkgs/tools/networking/opensnitch/daemon.nix

@@ -48,7 +48,12 @@ buildGoModule rec {
 
   postBuild = ''
     mv $GOPATH/bin/daemon $GOPATH/bin/opensnitchd
-    mkdir -p $out/lib/systemd/system
+    mkdir -p $out/etc/opensnitchd $out/lib/systemd/system
+    cp system-fw.json $out/etc/opensnitchd/
+    substitute default-config.json $out/etc/default-config.json \
+      --replace "/var/log/opensnitchd.log" "/dev/stdout" \
+      --replace "iptables" "nftables" \
+      --replace "ebpf" "proc"
     substitute opensnitchd.service $out/lib/systemd/system/opensnitchd.service \
       --replace "/usr/local/bin/opensnitchd" "$out/bin/opensnitchd" \
       --replace "/etc/opensnitchd/rules" "/var/lib/opensnitch/rules" \