samples/bpf/test_cgrp2_tc_kern.c

   1 /* Copyright (c) 2016 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 #define KBUILD_MODNAME "foo"
   8 #include <uapi/linux/if_ether.h>
   9 #include <uapi/linux/in6.h>
  10 #include <uapi/linux/ipv6.h>
  11 #include <uapi/linux/pkt_cls.h>
  12 #include <uapi/linux/bpf.h>
  13 #include <bpf/bpf_helpers.h>
  14
  15 /* copy of 'struct ethhdr' without __packed */
  16 struct eth_hdr {
  17         unsigned char   h_dest[ETH_ALEN];
  18         unsigned char   h_source[ETH_ALEN];
  19         unsigned short  h_proto;
  20 };
  21
  22 #define PIN_GLOBAL_NS           2
  23 struct bpf_elf_map {
  24         __u32 type;
  25         __u32 size_key;
  26         __u32 size_value;
  27         __u32 max_elem;
  28         __u32 flags;
  29         __u32 id;
  30         __u32 pinning;
  31 };
  32
  33 struct bpf_elf_map SEC("maps") test_cgrp2_array_pin = {
  34         .type           = BPF_MAP_TYPE_CGROUP_ARRAY,
  35         .size_key       = sizeof(uint32_t),
  36         .size_value     = sizeof(uint32_t),
  37         .pinning        = PIN_GLOBAL_NS,
  38         .max_elem       = 1,
  39 };
  40
  41 SEC("filter")
  42 int handle_egress(struct __sk_buff *skb)
  43 {
  44         void *data = (void *)(long)skb->data;
  45         struct eth_hdr *eth = data;
  46         struct ipv6hdr *ip6h = data + sizeof(*eth);
  47         void *data_end = (void *)(long)skb->data_end;
  48         char dont_care_msg[] = "dont care %04x %d\n";
  49         char pass_msg[] = "pass\n";
  50         char reject_msg[] = "reject\n";
  51
  52         /* single length check */
  53         if (data + sizeof(*eth) + sizeof(*ip6h) > data_end)
  54                 return TC_ACT_OK;
  55
  56         if (eth->h_proto != htons(ETH_P_IPV6) ||
  57             ip6h->nexthdr != IPPROTO_ICMPV6) {
  58                 bpf_trace_printk(dont_care_msg, sizeof(dont_care_msg),
  59                                  eth->h_proto, ip6h->nexthdr);
  60                 return TC_ACT_OK;
  61         } else if (bpf_skb_under_cgroup(skb, &test_cgrp2_array_pin, 0) != 1) {
  62                 bpf_trace_printk(pass_msg, sizeof(pass_msg));
  63                 return TC_ACT_OK;
  64         } else {
  65                 bpf_trace_printk(reject_msg, sizeof(reject_msg));
  66                 return TC_ACT_SHOT;
  67         }
  68 }
  69
  70 char _license[] SEC("license") = "GPL";