xdp_drop.c

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/resource.h>
#include <bpf/libbpf.h>
#include <bpf/bpf.h>
#include <bpf/btf.h>
#include <net/if.h>
#include <linux/if_link.h>
#include "xdp_drop.skel.h"

#define DEV_NAME "wlp0s20f3"

int main(int argc, char **argv)
{
	__u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST | XDP_FLAGS_SKB_MODE;
	struct xdp_drop_bpf *obj;
	LIBBPF_OPTS(bpf_xdp_attach_opts, attach_opts);
	int err = 0;

	struct rlimit rlim_new = {
		.rlim_cur = RLIM_INFINITY,
		.rlim_max = RLIM_INFINITY,
	};

	err = setrlimit(RLIMIT_MEMLOCK, &rlim_new);
	if (err) {
		fprintf(stderr, "failed to change rlimit\n");
		return 1;
	}

	unsigned int ifindex = if_nametoindex(DEV_NAME);
	if (ifindex == 0) {
		fprintf(stderr, "failed to find interface %s\n", DEV_NAME);
		return 1;
	}

	obj = xdp_drop_bpf__open();
	if (!obj) {
		fprintf(stderr, "failed to open and/or load BPF object\n");
		return 1;
	}

	err = xdp_drop_bpf__load(obj);
	if (err) {
		fprintf(stderr, "failed to load XDP BPF object %d\n", err);
		goto cleanup;
	}

	/* Attach the XDP program to the specified network interface */
	int prog_id = bpf_program__fd(obj->progs.xdp_prog_drop);
	err = bpf_xdp_attach(ifindex, prog_id, xdp_flags, &attach_opts);
	if (err) {
		fprintf(stderr, "failed to attach BPF programs\n");
		goto cleanup;
	}

	printf("Successfully started! ...\n");
	// system("cat /sys/kernel/debug/tracing/trace_pipe");
	while(1) {
		sleep(1);
	}

 cleanup:
	bpf_xdp_detach(ifindex, xdp_flags, &attach_opts);
	xdp_drop_bpf__destroy(obj);
	return err != 0;
}