net/netfilter/xt_bpf.c

   1 /* Xtables module to match packets using a BPF filter.
   2  * Copyright 2013 Google Inc.
   3  * Written by Willem de Bruijn <willemb@google.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/filter.h>
  13
  14 #include <linux/netfilter/xt_bpf.h>
  15 #include <linux/netfilter/x_tables.h>
  16
  17 MODULE_AUTHOR("Willem de Bruijn <willemb@google.com>");
  18 MODULE_DESCRIPTION("Xtables: BPF filter match");
  19 MODULE_LICENSE("GPL");
  20 MODULE_ALIAS("ipt_bpf");
  21 MODULE_ALIAS("ip6t_bpf");
  22
  23 static int bpf_mt_check(const struct xt_mtchk_param *par)
  24 {
  25         struct xt_bpf_info *info = par->matchinfo;
  26         struct sock_fprog program;
  27
  28         program.len = info->bpf_program_num_elem;
  29         program.filter = (struct sock_filter __user *) info->bpf_program;
  30         if (sk_unattached_filter_create(&info->filter, &program)) {
  31                 pr_info("bpf: check failed: parse error\n");
  32                 return -EINVAL;
  33         }
  34
  35         return 0;
  36 }
  37
  38 static bool bpf_mt(const struct sk_buff *skb, struct xt_action_param *par)
  39 {
  40         const struct xt_bpf_info *info = par->matchinfo;
  41
  42         return SK_RUN_FILTER(info->filter, skb);
  43 }
  44
  45 static void bpf_mt_destroy(const struct xt_mtdtor_param *par)
  46 {
  47         const struct xt_bpf_info *info = par->matchinfo;
  48         sk_unattached_filter_destroy(info->filter);
  49 }
  50
  51 static struct xt_match bpf_mt_reg __read_mostly = {
  52         .name           = "bpf",
  53         .revision       = 0,
  54         .family         = NFPROTO_UNSPEC,
  55         .checkentry     = bpf_mt_check,
  56         .match          = bpf_mt,
  57         .destroy        = bpf_mt_destroy,
  58         .matchsize      = sizeof(struct xt_bpf_info),
  59         .me             = THIS_MODULE,
  60 };
  61
  62 static int __init bpf_mt_init(void)
  63 {
  64         return xt_register_match(&bpf_mt_reg);
  65 }
  66
  67 static void __exit bpf_mt_exit(void)
  68 {
  69         xt_unregister_match(&bpf_mt_reg);
  70 }
  71
  72 module_init(bpf_mt_init);
  73 module_exit(bpf_mt_exit);