xdp_drop_ipv6_count.c

#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include <linux/if_ether.h>
#include <arpa/inet.h>

struct {
	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
	__type(key, __u32);
	__type(value, long);
	__uint(max_entries, 1);
} rxcnt SEC(".maps");

SEC("xdp_drop_ipv6")
int xdp_drop_ipv6_prog(struct xdp_md *ctx)
{
	void *data_end = (void *)(long)ctx->data_end;
	void *data = (void *)(long)ctx->data;
	struct ethhdr *eth = data;
	__u16 h_proto;
	__u32 key = 0;
	long *value;

	if (data + sizeof(struct ethhdr) > data_end)
		return XDP_DROP;

	h_proto = eth->h_proto;

	if (h_proto == htons(ETH_P_IPV6)) {
		value = bpf_map_lookup_elem(&rxcnt, &key);
		if (value)
			*value += 1;
		return XDP_DROP;
	}

	return XDP_PASS;
}

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