bekkalokk/phpfpm-*: systemd hardening

hosts/bekkalokk/configuration.nix

@@ -11,6 +11,7 @@
     ./services/kerberos
     ./services/mediawiki
     ./services/nginx.nix
+    ./services/phpfpm.nix
     ./services/vaultwarden.nix
     ./services/webmail
     ./services/website

hosts/bekkalokk/services/phpfpm.nix

@@ -0,0 +1,51 @@
+{ lib, ... }:
+let
+  pools = map (pool: "phpfpm-${pool}") [
+    "idp"
+    "mediawiki"
+    "pvv-nettsiden"
+    "roundcube"
+    "snappymail"
+  ];
+in
+{
+  # Source: https://www.pierreblazquez.com/2023/06/17/how-to-harden-apache-php-fpm-daemons-using-systemd/
+  systemd.services = lib.genAttrs pools (_: {
+    serviceConfig = let
+      caps = [
+        "CAP_NET_BIND_SERVICE"
+        "CAP_SETGID"
+        "CAP_SETUID"
+        "CAP_CHOWN"
+        "CAP_KILL"
+        "CAP_IPC_LOCK"
+        "CAP_DAC_OVERRIDE"
+      ];
+    in {
+      AmbientCapabilities = caps;
+      CapabilityBoundingSet = caps;
+      DeviceAllow = [ "" ];
+      LockPersonality = true;
+      MemoryDenyWriteExecute = false;
+      NoNewPrivileges = true;
+      PrivateMounts = true;
+      ProtectClock = true;
+      ProtectControlGroups = true;
+      ProtectHome = true;
+      ProtectHostname = true;
+      ProtectKernelLogs = true;
+      ProtectKernelModules = true;
+      ProtectKernelTunables = true;
+      RemoveIPC = true;
+      UMask = "0077";
+      RestrictNamespaces = "~mnt";
+      RestrictRealtime = true;
+      RestrictSUIDSGID = true;
+      SystemCallArchitectures = "native";
+      KeyringMode = "private";
+      SystemCallFilter = [
+        "@system-service"
+      ];
+    };
+  });
+}