LXR linux/tools/testing/selftests/bpf/test_pkt

   1/* Copyright (c) 2017 Facebook
   2 *
   3 * This program is free software; you can redistribute it and/or
   4 * modify it under the terms of version 2 of the GNU General Public
   5 * License as published by the Free Software Foundation.
   6 */
   7#include <stddef.h>
   8#include <string.h>
   9#include <linux/bpf.h>
  10#include <linux/if_ether.h>
  11#include <linux/if_packet.h>
  12#include <linux/ip.h>
  13#include <linux/ipv6.h>
  14#include <linux/in.h>
  15#include <linux/tcp.h>
  16#include <linux/pkt_cls.h>
  17#include "bpf_helpers.h"
  18#include "bpf_endian.h"
  19
  20#define barrier() __asm__ __volatile__("": : :"memory")
  21int _version SEC("version") = 1;
  22
  23SEC("test1")
  24int process(struct __sk_buff *skb)
  25{
  26        void *data_end = (void *)(long)skb->data_end;
  27        void *data = (void *)(long)skb->data;
  28        struct ethhdr *eth = (struct ethhdr *)(data);
  29        struct tcphdr *tcp = NULL;
  30        __u8 proto = 255;
  31        __u64 ihl_len;
  32
  33        if (eth + 1 > data_end)
  34                return TC_ACT_SHOT;
  35
  36        if (eth->h_proto == bpf_htons(ETH_P_IP)) {
  37                struct iphdr *iph = (struct iphdr *)(eth + 1);
  38
  39                if (iph + 1 > data_end)
  40                        return TC_ACT_SHOT;
  41                ihl_len = iph->ihl * 4;
  42                proto = iph->protocol;
  43                tcp = (struct tcphdr *)((void *)(iph) + ihl_len);
  44        } else if (eth->h_proto == bpf_htons(ETH_P_IPV6)) {
  45                struct ipv6hdr *ip6h = (struct ipv6hdr *)(eth + 1);
  46
  47                if (ip6h + 1 > data_end)
  48                        return TC_ACT_SHOT;
  49                ihl_len = sizeof(*ip6h);
  50                proto = ip6h->nexthdr;
  51                tcp = (struct tcphdr *)((void *)(ip6h) + ihl_len);
  52        }
  53
  54        if (tcp) {
  55                if (((void *)(tcp) + 20) > data_end || proto != 6)
  56                        return TC_ACT_SHOT;
  57                barrier(); /* to force ordering of checks */
  58                if (((void *)(tcp) + 18) > data_end)
  59                        return TC_ACT_SHOT;
  60                if (tcp->urg_ptr == 123)
  61                        return TC_ACT_OK;
  62        }
  63
  64        return TC_ACT_UNSPEC;
  65}
  66