nft_dup_ipv4.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (c) 2015 Pablo Neira Ayuso <pablo@netfilter.org>
  4 */
  5
  6#include <linux/kernel.h>
  7#include <linux/init.h>
  8#include <linux/module.h>
  9#include <linux/netlink.h>
 10#include <linux/netfilter.h>
 11#include <linux/netfilter/nf_tables.h>
 12#include <net/netfilter/nf_tables.h>
 13#include <net/netfilter/ipv4/nf_dup_ipv4.h>
 14
 15struct nft_dup_ipv4 {
 16	u8	sreg_addr;
 17	u8	sreg_dev;
 18};
 19
 20static void nft_dup_ipv4_eval(const struct nft_expr *expr,
 21			      struct nft_regs *regs,
 22			      const struct nft_pktinfo *pkt)
 23{
 24	struct nft_dup_ipv4 *priv = nft_expr_priv(expr);
 25	struct in_addr gw = {
 26		.s_addr = (__force __be32)regs->data[priv->sreg_addr],
 27	};
 28	int oif = priv->sreg_dev ? regs->data[priv->sreg_dev] : -1;
 29
 30	nf_dup_ipv4(nft_net(pkt), pkt->skb, nft_hook(pkt), &gw, oif);
 31}
 32
 33static int nft_dup_ipv4_init(const struct nft_ctx *ctx,
 34			     const struct nft_expr *expr,
 35			     const struct nlattr * const tb[])
 36{
 37	struct nft_dup_ipv4 *priv = nft_expr_priv(expr);
 38	int err;
 39
 40	if (tb[NFTA_DUP_SREG_ADDR] == NULL)
 41		return -EINVAL;
 42
 43	err = nft_parse_register_load(ctx, tb[NFTA_DUP_SREG_ADDR], &priv->sreg_addr,
 44				      sizeof(struct in_addr));
 45	if (err < 0)
 46		return err;
 47
 48	if (tb[NFTA_DUP_SREG_DEV])
 49		err = nft_parse_register_load(ctx, tb[NFTA_DUP_SREG_DEV],
 50					      &priv->sreg_dev, sizeof(int));
 51
 52	return err;
 53}
 54
 55static int nft_dup_ipv4_dump(struct sk_buff *skb,
 56			     const struct nft_expr *expr, bool reset)
 57{
 58	struct nft_dup_ipv4 *priv = nft_expr_priv(expr);
 59
 60	if (nft_dump_register(skb, NFTA_DUP_SREG_ADDR, priv->sreg_addr))
 61		goto nla_put_failure;
 62	if (priv->sreg_dev &&
 63	    nft_dump_register(skb, NFTA_DUP_SREG_DEV, priv->sreg_dev))
 64		goto nla_put_failure;
 65
 66	return 0;
 67
 68nla_put_failure:
 69	return -1;
 70}
 71
 72static struct nft_expr_type nft_dup_ipv4_type;
 73static 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	.reduce		= NFT_REDUCE_READONLY,
 80};
 81
 82static const struct nla_policy nft_dup_ipv4_policy[NFTA_DUP_MAX + 1] = {
 83	[NFTA_DUP_SREG_ADDR]	= { .type = NLA_U32 },
 84	[NFTA_DUP_SREG_DEV]	= { .type = NLA_U32 },
 85};
 86
 87static struct nft_expr_type nft_dup_ipv4_type __read_mostly = {
 88	.family		= NFPROTO_IPV4,
 89	.name		= "dup",
 90	.ops		= &nft_dup_ipv4_ops,
 91	.policy		= nft_dup_ipv4_policy,
 92	.maxattr	= NFTA_DUP_MAX,
 93	.owner		= THIS_MODULE,
 94};
 95
 96static int __init nft_dup_ipv4_module_init(void)
 97{
 98	return nft_register_expr(&nft_dup_ipv4_type);
 99}
100
101static void __exit nft_dup_ipv4_module_exit(void)
102{
103	nft_unregister_expr(&nft_dup_ipv4_type);
104}
105
106module_init(nft_dup_ipv4_module_init);
107module_exit(nft_dup_ipv4_module_exit);
108
109MODULE_LICENSE("GPL");
110MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
111MODULE_ALIAS_NFT_AF_EXPR(AF_INET, "dup");
112MODULE_DESCRIPTION("IPv4 nftables packet duplication support");