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 #include <linux/bpf.h>
  14
  15 #include <linux/netfilter/xt_bpf.h>
  16 #include <linux/netfilter/x_tables.h>
  17
  18 MODULE_AUTHOR("Willem de Bruijn <willemb@google.com>");
  19 MODULE_DESCRIPTION("Xtables: BPF filter match");
  20 MODULE_LICENSE("GPL");
  21 MODULE_ALIAS("ipt_bpf");
  22 MODULE_ALIAS("ip6t_bpf");
  23
  24 static int __bpf_mt_check_bytecode(struct sock_filter *insns, __u16 len,
  25                                    struct bpf_prog **ret)
  26 {
  27         struct sock_fprog_kern program;
  28
  29         program.len = len;
  30         program.filter = insns;
  31
  32         if (bpf_prog_create(ret, &program)) {
  33                 pr_info("bpf: check failed: parse error\n");
  34                 return -EINVAL;
  35         }
  36
  37         return 0;
  38 }
  39
  40 static int __bpf_mt_check_fd(int fd, struct bpf_prog **ret)
  41 {
  42         struct bpf_prog *prog;
  43
  44         prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_SOCKET_FILTER);
  45         if (IS_ERR(prog))
  46                 return PTR_ERR(prog);
  47
  48         *ret = prog;
  49         return 0;
  50 }
  51
  52 static int bpf_mt_check(const struct xt_mtchk_param *par)
  53 {
  54         struct xt_bpf_info *info = par->matchinfo;
  55
  56         return __bpf_mt_check_bytecode(info->bpf_program,
  57                                        info->bpf_program_num_elem,
  58                                        &info->filter);
  59 }
  60
  61 static int bpf_mt_check_v1(const struct xt_mtchk_param *par)
  62 {
  63         struct xt_bpf_info_v1 *info = par->matchinfo;
  64
  65         if (info->mode == XT_BPF_MODE_BYTECODE)
  66                 return __bpf_mt_check_bytecode(info->bpf_program,
  67                                                info->bpf_program_num_elem,
  68                                                &info->filter);
  69         else if (info->mode == XT_BPF_MODE_FD_PINNED ||
  70                  info->mode == XT_BPF_MODE_FD_ELF)
  71                 return __bpf_mt_check_fd(info->fd, &info->filter);
  72         else
  73                 return -EINVAL;
  74 }
  75
  76 static bool bpf_mt(const struct sk_buff *skb, struct xt_action_param *par)
  77 {
  78         const struct xt_bpf_info *info = par->matchinfo;
  79
  80         return BPF_PROG_RUN(info->filter, skb);
  81 }
  82
  83 static bool bpf_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
  84 {
  85         const struct xt_bpf_info_v1 *info = par->matchinfo;
  86
  87         return !!bpf_prog_run_save_cb(info->filter, (struct sk_buff *) skb);
  88 }
  89
  90 static void bpf_mt_destroy(const struct xt_mtdtor_param *par)
  91 {
  92         const struct xt_bpf_info *info = par->matchinfo;
  93
  94         bpf_prog_destroy(info->filter);
  95 }
  96
  97 static void bpf_mt_destroy_v1(const struct xt_mtdtor_param *par)
  98 {
  99         const struct xt_bpf_info_v1 *info = par->matchinfo;
 100
 101         bpf_prog_destroy(info->filter);
 102 }
 103
 104 static struct xt_match bpf_mt_reg[] __read_mostly = {
 105         {
 106                 .name           = "bpf",
 107                 .revision       = 0,
 108                 .family         = NFPROTO_UNSPEC,
 109                 .checkentry     = bpf_mt_check,
 110                 .match          = bpf_mt,
 111                 .destroy        = bpf_mt_destroy,
 112                 .matchsize      = sizeof(struct xt_bpf_info),
 113                 .usersize       = offsetof(struct xt_bpf_info, filter),
 114                 .me             = THIS_MODULE,
 115         },
 116         {
 117                 .name           = "bpf",
 118                 .revision       = 1,
 119                 .family         = NFPROTO_UNSPEC,
 120                 .checkentry     = bpf_mt_check_v1,
 121                 .match          = bpf_mt_v1,
 122                 .destroy        = bpf_mt_destroy_v1,
 123                 .matchsize      = sizeof(struct xt_bpf_info_v1),
 124                 .usersize       = offsetof(struct xt_bpf_info_v1, filter),
 125                 .me             = THIS_MODULE,
 126         },
 127 };
 128
 129 static int __init bpf_mt_init(void)
 130 {
 131         return xt_register_matches(bpf_mt_reg, ARRAY_SIZE(bpf_mt_reg));
 132 }
 133
 134 static void __exit bpf_mt_exit(void)
 135 {
 136         xt_unregister_matches(bpf_mt_reg, ARRAY_SIZE(bpf_mt_reg));
 137 }
 138
 139 module_init(bpf_mt_init);
 140 module_exit(bpf_mt_exit);