samples/bpf/test_cgrp2_tc.bpf.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 "vmlinux.h"
   9 #include "net_shared.h"
  10 #include <bpf/bpf_helpers.h>
  11
  12 /* copy of 'struct ethhdr' without __packed */
  13 struct eth_hdr {
  14         unsigned char   h_dest[ETH_ALEN];
  15         unsigned char   h_source[ETH_ALEN];
  16         unsigned short  h_proto;
  17 };
  18
  19 struct {
  20         __uint(type, BPF_MAP_TYPE_CGROUP_ARRAY);
  21         __type(key, u32);
  22         __type(value, u32);
  23         __uint(pinning, LIBBPF_PIN_BY_NAME);
  24         __uint(max_entries, 1);
  25 } test_cgrp2_array_pin SEC(".maps");
  26
  27 SEC("filter")
  28 int handle_egress(struct __sk_buff *skb)
  29 {
  30         void *data = (void *)(long)skb->data;
  31         struct eth_hdr *eth = data;
  32         struct ipv6hdr *ip6h = data + sizeof(*eth);
  33         void *data_end = (void *)(long)skb->data_end;
  34         char dont_care_msg[] = "dont care %04x %d\n";
  35         char pass_msg[] = "pass\n";
  36         char reject_msg[] = "reject\n";
  37
  38         /* single length check */
  39         if (data + sizeof(*eth) + sizeof(*ip6h) > data_end)
  40                 return TC_ACT_OK;
  41
  42         if (eth->h_proto != bpf_htons(ETH_P_IPV6) ||
  43             ip6h->nexthdr != IPPROTO_ICMPV6) {
  44                 bpf_trace_printk(dont_care_msg, sizeof(dont_care_msg),
  45                                  eth->h_proto, ip6h->nexthdr);
  46                 return TC_ACT_OK;
  47         } else if (bpf_skb_under_cgroup(skb, &test_cgrp2_array_pin, 0) != 1) {
  48                 bpf_trace_printk(pass_msg, sizeof(pass_msg));
  49                 return TC_ACT_OK;
  50         } else {
  51                 bpf_trace_printk(reject_msg, sizeof(reject_msg));
  52                 return TC_ACT_SHOT;
  53         }
  54 }
  55
  56 char _license[] SEC("license") = "GPL";