bpf/progs/test_xdp_meta.c

0001 #include <linux/bpf.h>
0002 #include <linux/if_ether.h>
0003 #include <linux/pkt_cls.h>
0004
0005 #include <bpf/bpf_helpers.h>
0006
0007 #define __round_mask(x, y) ((__typeof__(x))((y) - 1))
0008 #define round_up(x, y) ((((x) - 1) | __round_mask(x, y)) + 1)
0009 #define ctx_ptr(ctx, mem) (void *)(unsigned long)ctx->mem
0010
0011 SEC("t")
0012 int ing_cls(struct __sk_buff *ctx)
0013 {
0014     __u8 *data, *data_meta, *data_end;
0015     __u32 diff = 0;
0016
0017     data_meta = ctx_ptr(ctx, data_meta);
0018     data_end  = ctx_ptr(ctx, data_end);
0019     data      = ctx_ptr(ctx, data);
0020
0021     if (data + ETH_ALEN > data_end ||
0022         data_meta + round_up(ETH_ALEN, 4) > data)
0023         return TC_ACT_SHOT;
0024
0025     diff |= ((__u32 *)data_meta)[0] ^ ((__u32 *)data)[0];
0026     diff |= ((__u16 *)data_meta)[2] ^ ((__u16 *)data)[2];
0027
0028     return diff ? TC_ACT_SHOT : TC_ACT_OK;
0029 }
0030
0031 SEC("x")
0032 int ing_xdp(struct xdp_md *ctx)
0033 {
0034     __u8 *data, *data_meta, *data_end;
0035     int ret;
0036
0037     ret = bpf_xdp_adjust_meta(ctx, -round_up(ETH_ALEN, 4));
0038     if (ret < 0)
0039         return XDP_DROP;
0040
0041     data_meta = ctx_ptr(ctx, data_meta);
0042     data_end  = ctx_ptr(ctx, data_end);
0043     data      = ctx_ptr(ctx, data);
0044
0045     if (data + ETH_ALEN > data_end ||
0046         data_meta + round_up(ETH_ALEN, 4) > data)
0047         return XDP_DROP;
0048
0049     __builtin_memcpy(data_meta, data, ETH_ALEN);
0050     return XDP_PASS;
0051 }
0052
0053 char _license[] SEC("license") = "GPL";