xdp_prog_kern.c

/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/bpf.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#include <linux/if_vlan.h>
#include <linux/ip.h>
#include <linux/in.h>
#include <stdbool.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>

/* to u64 in host order */
static inline __u64 ether_addr_to_u64(const __u8 *addr)
{
	__u64 u = 0;
	int i;

	for (i = ETH_ALEN - 1; i >= 0; i--)
		u = u << 8 | addr[i];
	return u;
}

SEC("xdp")
int  xdp_prog_simple(struct xdp_md *ctx)
{
	void *data = (void *)(long)ctx->data;
	void *data_end = (void *)(long)ctx->data_end;
	struct ethhdr *eth = data;
	__u64 offset = sizeof(*eth);

	if ((void *)eth + offset > data_end)
		return 0;

	bpf_printk("src: %llu, dst: %llu, proto: %u\n",
		   ether_addr_to_u64(eth->h_source),
		   ether_addr_to_u64(eth->h_dest),
		   bpf_ntohs(eth->h_proto));

	return XDP_PASS;
}

char _license[] SEC("license") = "GPL";