// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2015 Pablo Neira Ayuso <pablo@netfilter.org>
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/ipv6/nf_dup_ipv6.h>

struct nft_dup_ipv6 {
        u8      sreg_addr;
        u8      sreg_dev;
};

static void nft_dup_ipv6_eval(const struct nft_expr *expr,
                              struct nft_regs *regs,
                              const struct nft_pktinfo *pkt)
{
        struct nft_dup_ipv6 *priv = nft_expr_priv(expr);
        struct in6_addr *gw = (struct in6_addr *)&regs->data[priv->sreg_addr];
        int oif = priv->sreg_dev ? regs->data[priv->sreg_dev] : -1;

        nf_dup_ipv6(nft_net(pkt), pkt->skb, nft_hook(pkt), gw, oif);
}

static int nft_dup_ipv6_init(const struct nft_ctx *ctx,
                             const struct nft_expr *expr,
                             const struct nlattr * const tb[])
{
        struct nft_dup_ipv6 *priv = nft_expr_priv(expr);
        int err;

        if (tb[NFTA_DUP_SREG_ADDR] == NULL)
                return -EINVAL;

        err = nft_parse_register_load(ctx, tb[NFTA_DUP_SREG_ADDR], &priv->sreg_addr,
                                      sizeof(struct in6_addr));
        if (err < 0)
                return err;

        if (tb[NFTA_DUP_SREG_DEV])
                err = nft_parse_register_load(ctx, tb[NFTA_DUP_SREG_DEV],
                                              &priv->sreg_dev, sizeof(int));

        return err;
}

static int nft_dup_ipv6_dump(struct sk_buff *skb,
                             const struct nft_expr *expr, bool reset)
{
        struct nft_dup_ipv6 *priv = nft_expr_priv(expr);

        if (nft_dump_register(skb, NFTA_DUP_SREG_ADDR, priv->sreg_addr))
                goto nla_put_failure;
        if (priv->sreg_dev &&
            nft_dump_register(skb, NFTA_DUP_SREG_DEV, priv->sreg_dev))
                goto nla_put_failure;

        return 0;

nla_put_failure:
        return -1;
}

static struct nft_expr_type nft_dup_ipv6_type;
static const struct nft_expr_ops nft_dup_ipv6_ops = {
        .type           = &nft_dup_ipv6_type,
        .size           = NFT_EXPR_SIZE(sizeof(struct nft_dup_ipv6)),
        .eval           = nft_dup_ipv6_eval,
        .init           = nft_dup_ipv6_init,
        .dump           = nft_dup_ipv6_dump,
        .reduce         = NFT_REDUCE_READONLY,
};

static const struct nla_policy nft_dup_ipv6_policy[NFTA_DUP_MAX + 1] = {
        [NFTA_DUP_SREG_ADDR]    = { .type = NLA_U32 },
        [NFTA_DUP_SREG_DEV]     = { .type = NLA_U32 },
};

static struct nft_expr_type nft_dup_ipv6_type __read_mostly = {
        .family         = NFPROTO_IPV6,
        .name           = "dup",
        .ops            = &nft_dup_ipv6_ops,
        .policy         = nft_dup_ipv6_policy,
        .maxattr        = NFTA_DUP_MAX,
        .owner          = THIS_MODULE,
};

static int __init nft_dup_ipv6_module_init(void)
{
        return nft_register_expr(&nft_dup_ipv6_type);
}

static void __exit nft_dup_ipv6_module_exit(void)
{
        nft_unregister_expr(&nft_dup_ipv6_type);
}

module_init(nft_dup_ipv6_module_init);
module_exit(nft_dup_ipv6_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
MODULE_ALIAS_NFT_AF_EXPR(AF_INET6, "dup");
MODULE_DESCRIPTION("IPv6 nftables packet duplication support");