// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * IP6 tables REJECT target module
 * Linux INET6 implementation
 *
 * Copyright (C)2003 USAGI/WIDE Project
 *
 * Authors:
 *      Yasuyuki Kozakai        <yasuyuki.kozakai@toshiba.co.jp>
 *
 * Copyright (c) 2005-2007 Patrick McHardy <kaber@trash.net>
 *
 * Based on net/ipv4/netfilter/ipt_REJECT.c
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/gfp.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/icmpv6.h>
#include <linux/netdevice.h>
#include <net/icmp.h>
#include <net/flow.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_REJECT.h>

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

MODULE_AUTHOR("Yasuyuki KOZAKAI <yasuyuki.kozakai@toshiba.co.jp>");
MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv6");
MODULE_LICENSE("GPL");

static unsigned int
reject_tg6(struct sk_buff *skb, const struct xt_action_param *par)
{
        const struct ip6t_reject_info *reject = par->targinfo;
        struct net *net = xt_net(par);

        switch (reject->with) {
        case IP6T_ICMP6_NO_ROUTE:
                nf_send_unreach6(net, skb, ICMPV6_NOROUTE, xt_hooknum(par));
                break;
        case IP6T_ICMP6_ADM_PROHIBITED:
                nf_send_unreach6(net, skb, ICMPV6_ADM_PROHIBITED,
                                 xt_hooknum(par));
                break;
        case IP6T_ICMP6_NOT_NEIGHBOUR:
                nf_send_unreach6(net, skb, ICMPV6_NOT_NEIGHBOUR,
                                 xt_hooknum(par));
                break;
        case IP6T_ICMP6_ADDR_UNREACH:
                nf_send_unreach6(net, skb, ICMPV6_ADDR_UNREACH,
                                 xt_hooknum(par));
                break;
        case IP6T_ICMP6_PORT_UNREACH:
                nf_send_unreach6(net, skb, ICMPV6_PORT_UNREACH,
                                 xt_hooknum(par));
                break;
        case IP6T_ICMP6_ECHOREPLY:
                /* Do nothing */
                break;
        case IP6T_TCP_RESET:
                nf_send_reset6(net, par->state->sk, skb, xt_hooknum(par));
                break;
        case IP6T_ICMP6_POLICY_FAIL:
                nf_send_unreach6(net, skb, ICMPV6_POLICY_FAIL, xt_hooknum(par));
                break;
        case IP6T_ICMP6_REJECT_ROUTE:
                nf_send_unreach6(net, skb, ICMPV6_REJECT_ROUTE,
                                 xt_hooknum(par));
                break;
        }

        return NF_DROP;
}

static int reject_tg6_check(const struct xt_tgchk_param *par)
{
        const struct ip6t_reject_info *rejinfo = par->targinfo;
        const struct ip6t_entry *e = par->entryinfo;

        if (rejinfo->with == IP6T_ICMP6_ECHOREPLY) {
                pr_info_ratelimited("ECHOREPLY is not supported\n");
                return -EINVAL;
        } else if (rejinfo->with == IP6T_TCP_RESET) {
                /* Must specify that it's a TCP packet */
                if (!(e->ipv6.flags & IP6T_F_PROTO) ||
                    e->ipv6.proto != IPPROTO_TCP ||
                    (e->ipv6.invflags & XT_INV_PROTO)) {
                        pr_info_ratelimited("TCP_RESET illegal for non-tcp\n");
                        return -EINVAL;
                }
        }
        return 0;
}

static struct xt_target reject_tg6_reg __read_mostly = {
        .name           = "REJECT",
        .family         = NFPROTO_IPV6,
        .target         = reject_tg6,
        .targetsize     = sizeof(struct ip6t_reject_info),
        .table          = "filter",
        .hooks          = (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD) |
                          (1 << NF_INET_LOCAL_OUT),
        .checkentry     = reject_tg6_check,
        .me             = THIS_MODULE
};

static int __init reject_tg6_init(void)
{
        return xt_register_target(&reject_tg6_reg);
}

static void __exit reject_tg6_exit(void)
{
        xt_unregister_target(&reject_tg6_reg);
}

module_init(reject_tg6_init);
module_exit(reject_tg6_exit);