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

   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")
  18int _version SEC("version") = 1;
  19
  20SEC("test1")
  21int 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}
  63