// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2014 Patrick McHardy <kaber@trash.net>
 */

#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/nft_reject.h>
#include <net/netfilter/ipv4/nf_reject.h>
#include <net/netfilter/ipv6/nf_reject.h>

static void nft_reject_inet_eval(const struct nft_expr *expr,
                                 struct nft_regs *regs,
                                 const struct nft_pktinfo *pkt)
{
        struct nft_reject *priv = nft_expr_priv(expr);

        switch (nft_pf(pkt)) {
        case NFPROTO_IPV4:
                switch (priv->type) {
                case NFT_REJECT_ICMP_UNREACH:
                        nf_send_unreach(pkt->skb, priv->icmp_code,
                                        nft_hook(pkt));
                        break;
                case NFT_REJECT_TCP_RST:
                        nf_send_reset(nft_net(pkt), nft_sk(pkt),
                                      pkt->skb, nft_hook(pkt));
                        break;
                case NFT_REJECT_ICMPX_UNREACH:
                        nf_send_unreach(pkt->skb,
                                        nft_reject_icmp_code(priv->icmp_code),
                                        nft_hook(pkt));
                        break;
                }
                break;
        case NFPROTO_IPV6:
                switch (priv->type) {
                case NFT_REJECT_ICMP_UNREACH:
                        nf_send_unreach6(nft_net(pkt), pkt->skb,
                                         priv->icmp_code, nft_hook(pkt));
                        break;
                case NFT_REJECT_TCP_RST:
                        nf_send_reset6(nft_net(pkt), nft_sk(pkt),
                                       pkt->skb, nft_hook(pkt));
                        break;
                case NFT_REJECT_ICMPX_UNREACH:
                        nf_send_unreach6(nft_net(pkt), pkt->skb,
                                         nft_reject_icmpv6_code(priv->icmp_code),
                                         nft_hook(pkt));
                        break;
                }
                break;
        }

        regs->verdict.code = NF_DROP;
}

static int nft_reject_inet_validate(const struct nft_ctx *ctx,
                                    const struct nft_expr *expr)
{
        return nft_chain_validate_hooks(ctx->chain,
                                        (1 << NF_INET_LOCAL_IN) |
                                        (1 << NF_INET_FORWARD) |
                                        (1 << NF_INET_LOCAL_OUT) |
                                        (1 << NF_INET_PRE_ROUTING) |
                                        (1 << NF_INET_INGRESS));
}

static struct nft_expr_type nft_reject_inet_type;
static const struct nft_expr_ops nft_reject_inet_ops = {
        .type           = &nft_reject_inet_type,
        .size           = NFT_EXPR_SIZE(sizeof(struct nft_reject)),
        .eval           = nft_reject_inet_eval,
        .init           = nft_reject_init,
        .dump           = nft_reject_dump,
        .validate       = nft_reject_inet_validate,
        .reduce         = NFT_REDUCE_READONLY,
};

static struct nft_expr_type nft_reject_inet_type __read_mostly = {
        .family         = NFPROTO_INET,
        .name           = "reject",
        .ops            = &nft_reject_inet_ops,
        .policy         = nft_reject_policy,
        .maxattr        = NFTA_REJECT_MAX,
        .owner          = THIS_MODULE,
};

static int __init nft_reject_inet_module_init(void)
{
        return nft_register_expr(&nft_reject_inet_type);
}

static void __exit nft_reject_inet_module_exit(void)
{
        nft_unregister_expr(&nft_reject_inet_type);
}

module_init(nft_reject_inet_module_init);
module_exit(nft_reject_inet_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_ALIAS_NFT_AF_EXPR(1, "reject");
MODULE_DESCRIPTION("Netfilter nftables reject inet support");