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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2017 Facebook
   3  */
   4 #include <stddef.h>
   5 #include <string.h>
   6 #include <linux/bpf.h>
   7 #include <linux/if_ether.h>
   8 #include <linux/if_packet.h>
   9 #include <linux/ip.h>
  10 #include <linux/ipv6.h>
  11 #include <linux/in.h>
  12 #include <linux/tcp.h>
  13 #include <linux/pkt_cls.h>
  14 #include "bpf_helpers.h"
  15 #include "bpf_endian.h"
  16
  17 #define barrier() __asm__ __volatile__("": : :"memory")
  18 int _version SEC("version") = 1;
  19
  20 SEC("test1")
  21 int process(struct __sk_buff *skb)
  22 {
  23         void *data_end = (void *)(long)skb->data_end;
  24         void *data = (void *)(long)skb->data;
  25         struct ethhdr *eth = (struct ethhdr *)(data);
  26         struct tcphdr *tcp = NULL;
  27         __u8 proto = 255;
  28         __u64 ihl_len;
  29
  30         if (eth + 1 > data_end)
  31                 return TC_ACT_SHOT;
  32
  33         if (eth->h_proto == bpf_htons(ETH_P_IP)) {
  34                 struct iphdr *iph = (struct iphdr *)(eth + 1);
  35
  36                 if (iph + 1 > data_end)
  37                         return TC_ACT_SHOT;
  38                 ihl_len = iph->ihl * 4;
  39                 proto = iph->protocol;
  40                 tcp = (struct tcphdr *)((void *)(iph) + ihl_len);
  41         } else if (eth->h_proto == bpf_htons(ETH_P_IPV6)) {
  42                 struct ipv6hdr *ip6h = (struct ipv6hdr *)(eth + 1);
  43
  44                 if (ip6h + 1 > data_end)
  45                         return TC_ACT_SHOT;
  46                 ihl_len = sizeof(*ip6h);
  47                 proto = ip6h->nexthdr;
  48                 tcp = (struct tcphdr *)((void *)(ip6h) + ihl_len);
  49         }
  50
  51         if (tcp) {
  52                 if (((void *)(tcp) + 20) > data_end || proto != 6)
  53                         return TC_ACT_SHOT;
  54                 barrier(); /* to force ordering of checks */
  55                 if (((void *)(tcp) + 18) > data_end)
  56                         return TC_ACT_SHOT;
  57                 if (tcp->urg_ptr == 123)
  58                         return TC_ACT_OK;
  59         }
  60
  61         return TC_ACT_UNSPEC;
  62 }