54 lines · c
1#include <linux/bpf.h>2#include <linux/if_ether.h>3#include <linux/pkt_cls.h>4 5#include <bpf/bpf_helpers.h>6 7#define __round_mask(x, y) ((__typeof__(x))((y) - 1))8#define round_up(x, y) ((((x) - 1) | __round_mask(x, y)) + 1)9#define ctx_ptr(ctx, mem) (void *)(unsigned long)ctx->mem10 11SEC("t")12int ing_cls(struct __sk_buff *ctx)13{14 __u8 *data, *data_meta, *data_end;15 __u32 diff = 0;16 17 data_meta = ctx_ptr(ctx, data_meta);18 data_end = ctx_ptr(ctx, data_end);19 data = ctx_ptr(ctx, data);20 21 if (data + ETH_ALEN > data_end ||22 data_meta + round_up(ETH_ALEN, 4) > data)23 return TC_ACT_SHOT;24 25 diff |= ((__u32 *)data_meta)[0] ^ ((__u32 *)data)[0];26 diff |= ((__u16 *)data_meta)[2] ^ ((__u16 *)data)[2];27 28 return diff ? TC_ACT_SHOT : TC_ACT_OK;29}30 31SEC("x")32int ing_xdp(struct xdp_md *ctx)33{34 __u8 *data, *data_meta, *data_end;35 int ret;36 37 ret = bpf_xdp_adjust_meta(ctx, -round_up(ETH_ALEN, 4));38 if (ret < 0)39 return XDP_DROP;40 41 data_meta = ctx_ptr(ctx, data_meta);42 data_end = ctx_ptr(ctx, data_end);43 data = ctx_ptr(ctx, data);44 45 if (data + ETH_ALEN > data_end ||46 data_meta + round_up(ETH_ALEN, 4) > data)47 return XDP_DROP;48 49 __builtin_memcpy(data_meta, data, ETH_ALEN);50 return XDP_PASS;51}52 53char _license[] SEC("license") = "GPL";54