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

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/bpf.h>
   3 #include <bpf/bpf_endian.h>
   4 #include <bpf/bpf_helpers.h>
   5 #include <linux/ip.h>
   6 #include "bpf_tracing_net.h"
   7
   8 /* We don't care about whether the packet can be received by network stack.
   9  * Just care if the packet is sent to the correct device at correct direction
  10  * and not panic the kernel.
  11  */
  12 static int prepend_dummy_mac(struct __sk_buff *skb)
  13 {
  14         char mac[] = {0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0xf,
  15                       0xe, 0xd, 0xc, 0xb, 0xa, 0x08, 0x00};
  16
  17         if (bpf_skb_change_head(skb, ETH_HLEN, 0))
  18                 return -1;
  19
  20         if (bpf_skb_store_bytes(skb, 0, mac, sizeof(mac), 0))
  21                 return -1;
  22
  23         return 0;
  24 }
  25
  26 /* Use the last byte of IP address to redirect the packet */
  27 static int get_redirect_target(struct __sk_buff *skb)
  28 {
  29         struct iphdr *iph = NULL;
  30         void *start = (void *)(long)skb->data;
  31         void *end = (void *)(long)skb->data_end;
  32
  33         if (start + sizeof(*iph) > end)
  34                 return -1;
  35
  36         iph = (struct iphdr *)start;
  37         return bpf_ntohl(iph->daddr) & 0xff;
  38 }
  39
  40 SEC("redir_ingress")
  41 int test_lwt_redirect_in(struct __sk_buff *skb)
  42 {
  43         int target = get_redirect_target(skb);
  44
  45         if (target < 0)
  46                 return BPF_OK;
  47
  48         if (prepend_dummy_mac(skb))
  49                 return BPF_DROP;
  50
  51         return bpf_redirect(target, BPF_F_INGRESS);
  52 }
  53
  54 SEC("redir_egress")
  55 int test_lwt_redirect_out(struct __sk_buff *skb)
  56 {
  57         int target = get_redirect_target(skb);
  58
  59         if (target < 0)
  60                 return BPF_OK;
  61
  62         if (prepend_dummy_mac(skb))
  63                 return BPF_DROP;
  64
  65         return bpf_redirect(target, 0);
  66 }
  67
  68 SEC("redir_egress_nomac")
  69 int test_lwt_redirect_out_nomac(struct __sk_buff *skb)
  70 {
  71         int target = get_redirect_target(skb);
  72
  73         if (target < 0)
  74                 return BPF_OK;
  75
  76         return bpf_redirect(target, 0);
  77 }
  78
  79 SEC("redir_ingress_nomac")
  80 int test_lwt_redirect_in_nomac(struct __sk_buff *skb)
  81 {
  82         int target = get_redirect_target(skb);
  83
  84         if (target < 0)
  85                 return BPF_OK;
  86
  87         return bpf_redirect(target, BPF_F_INGRESS);
  88 }
  89
  90 char _license[] SEC("license") = "GPL";