net/ipv4/netfilter/nft_dup_ipv4.c

   1 /*
   2  * Copyright (c) 2015 Pablo Neira Ayuso <pablo@netfilter.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 as published by
   6  * the Free Software Foundation.
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12 #include <linux/netlink.h>
  13 #include <linux/netfilter.h>
  14 #include <linux/netfilter/nf_tables.h>
  15 #include <net/netfilter/nf_tables.h>
  16 #include <net/netfilter/ipv4/nf_dup_ipv4.h>
  17
  18 struct nft_dup_ipv4 {
  19         enum nft_registers      sreg_addr:8;
  20         enum nft_registers      sreg_dev:8;
  21 };
  22
  23 static void nft_dup_ipv4_eval(const struct nft_expr *expr,
  24                               struct nft_regs *regs,
  25                               const struct nft_pktinfo *pkt)
  26 {
  27         struct nft_dup_ipv4 *priv = nft_expr_priv(expr);
  28         struct in_addr gw = {
  29                 .s_addr = (__force __be32)regs->data[priv->sreg_addr],
  30         };
  31         int oif = regs->data[priv->sreg_dev];
  32
  33         nf_dup_ipv4(pkt->skb, pkt->hook, &gw, oif);
  34 }
  35
  36 static int nft_dup_ipv4_init(const struct nft_ctx *ctx,
  37                              const struct nft_expr *expr,
  38                              const struct nlattr * const tb[])
  39 {
  40         struct nft_dup_ipv4 *priv = nft_expr_priv(expr);
  41         int err;
  42
  43         if (tb[NFTA_DUP_SREG_ADDR] == NULL)
  44                 return -EINVAL;
  45
  46         priv->sreg_addr = nft_parse_register(tb[NFTA_DUP_SREG_ADDR]);
  47         err = nft_validate_register_load(priv->sreg_addr, sizeof(struct in_addr));
  48         if (err < 0)
  49                 return err;
  50
  51         if (tb[NFTA_DUP_SREG_DEV] != NULL) {
  52                 priv->sreg_dev = nft_parse_register(tb[NFTA_DUP_SREG_DEV]);
  53                 return nft_validate_register_load(priv->sreg_dev, sizeof(int));
  54         }
  55         return 0;
  56 }
  57
  58 static int nft_dup_ipv4_dump(struct sk_buff *skb, const struct nft_expr *expr)
  59 {
  60         struct nft_dup_ipv4 *priv = nft_expr_priv(expr);
  61
  62         if (nft_dump_register(skb, NFTA_DUP_SREG_ADDR, priv->sreg_addr) ||
  63             nft_dump_register(skb, NFTA_DUP_SREG_DEV, priv->sreg_dev))
  64                 goto nla_put_failure;
  65
  66         return 0;
  67
  68 nla_put_failure:
  69         return -1;
  70 }
  71
  72 static struct nft_expr_type nft_dup_ipv4_type;
  73 static const struct nft_expr_ops nft_dup_ipv4_ops = {
  74         .type           = &nft_dup_ipv4_type,
  75         .size           = NFT_EXPR_SIZE(sizeof(struct nft_dup_ipv4)),
  76         .eval           = nft_dup_ipv4_eval,
  77         .init           = nft_dup_ipv4_init,
  78         .dump           = nft_dup_ipv4_dump,
  79 };
  80
  81 static const struct nla_policy nft_dup_ipv4_policy[NFTA_DUP_MAX + 1] = {
  82         [NFTA_DUP_SREG_ADDR]    = { .type = NLA_U32 },
  83         [NFTA_DUP_SREG_DEV]     = { .type = NLA_U32 },
  84 };
  85
  86 static struct nft_expr_type nft_dup_ipv4_type __read_mostly = {
  87         .family         = NFPROTO_IPV4,
  88         .name           = "dup",
  89         .ops            = &nft_dup_ipv4_ops,
  90         .policy         = nft_dup_ipv4_policy,
  91         .maxattr        = NFTA_DUP_MAX,
  92         .owner          = THIS_MODULE,
  93 };
  94
  95 static int __init nft_dup_ipv4_module_init(void)
  96 {
  97         return nft_register_expr(&nft_dup_ipv4_type);
  98 }
  99
 100 static void __exit nft_dup_ipv4_module_exit(void)
 101 {
 102         nft_unregister_expr(&nft_dup_ipv4_type);
 103 }
 104
 105 module_init(nft_dup_ipv4_module_init);
 106 module_exit(nft_dup_ipv4_module_exit);
 107
 108 MODULE_LICENSE("GPL");
 109 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 110 MODULE_ALIAS_NFT_AF_EXPR(AF_INET, "dup");