Add dropworld

dropworld/default.nix

@@ -0,0 +1,16 @@
+{clangStdenv, libbpf, ...}: clangStdenv.mkDerivation {
+  name = "dropworld";
+  src = ./.;
+  hardeningDisable = [ "stackprotector" "zerocallusedregs" ];
+  dontFixup = true;
+  buildInputs = [ libbpf ];
+
+  buildPhase = ''
+    clang -O2 -target bpf -g -c dropworld.c -o dropworld.o
+  '';
+
+  installPhase = ''
+    mkdir $out
+    cp dropworld.o $out
+  '';
+}

dropworld/dropworld.c

@@ -0,0 +1,9 @@
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+SEC("xdp")
+int xdp_drop(struct xdp_md *ctx) {
+    return XDP_DROP; // Drop all packets
+}
+
+char LICENSE[] SEC("license") = "GPL";