tools/testing/selftests/bpf/progs/load_bytes_relative.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2
   3 /*
   4  * Copyright 2020 Google LLC.
   5  */
   6
   7 #include <errno.h>
   8 #include <linux/bpf.h>
   9 #include <linux/if_ether.h>
  10 #include <linux/ip.h>
  11 #include <bpf/bpf_helpers.h>
  12
  13 struct {
  14         __uint(type, BPF_MAP_TYPE_ARRAY);
  15         __uint(max_entries, 1);
  16         __type(key, __u32);
  17         __type(value, __u32);
  18 } test_result SEC(".maps");
  19
  20 SEC("cgroup_skb/egress")
  21 int load_bytes_relative(struct __sk_buff *skb)
  22 {
  23         struct ethhdr eth;
  24         struct iphdr iph;
  25
  26         __u32 map_key = 0;
  27         __u32 test_passed = 0;
  28
  29         /* MAC header is not set by the time cgroup_skb/egress triggers */
  30         if (bpf_skb_load_bytes_relative(skb, 0, &eth, sizeof(eth),
  31                                         BPF_HDR_START_MAC) != -EFAULT)
  32                 goto fail;
  33
  34         if (bpf_skb_load_bytes_relative(skb, 0, &iph, sizeof(iph),
  35                                         BPF_HDR_START_NET))
  36                 goto fail;
  37
  38         if (bpf_skb_load_bytes_relative(skb, 0xffff, &iph, sizeof(iph),
  39                                         BPF_HDR_START_NET) != -EFAULT)
  40                 goto fail;
  41
  42         test_passed = 1;
  43
  44 fail:
  45         bpf_map_update_elem(&test_result, &map_key, &test_passed, BPF_ANY);
  46
  47         return 1;
  48 }