// SPDX-License-Identifier: GPL-2.0-only
/*
 * This is a module which is used for logging packets.
 */

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/ip.h>
#include <net/ipv6.h>
#include <net/icmp.h>
#include <net/udp.h>
#include <net/tcp.h>
#include <net/route.h>

#include <linux/netfilter.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_LOG.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <net/netfilter/nf_log.h>

static unsigned int
log_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
        const struct xt_log_info *loginfo = par->targinfo;
        struct net *net = xt_net(par);
        struct nf_loginfo li;

        li.type = NF_LOG_TYPE_LOG;
        li.u.log.level = loginfo->level;
        li.u.log.logflags = loginfo->logflags;

        nf_log_packet(net, xt_family(par), xt_hooknum(par), skb, xt_in(par),
                      xt_out(par), &li, "%s", loginfo->prefix);
        return XT_CONTINUE;
}

static int log_tg_check(const struct xt_tgchk_param *par)
{
        const struct xt_log_info *loginfo = par->targinfo;
        int ret;

        if (par->family != NFPROTO_IPV4 && par->family != NFPROTO_IPV6)
                return -EINVAL;

        if (loginfo->level >= 8) {
                pr_debug("level %u >= 8\n", loginfo->level);
                return -EINVAL;
        }

        if (loginfo->prefix[sizeof(loginfo->prefix)-1] != '\0') {
                pr_debug("prefix is not null-terminated\n");
                return -EINVAL;
        }

        ret = nf_logger_find_get(par->family, NF_LOG_TYPE_LOG);
        if (ret != 0 && !par->nft_compat) {
                request_module("%s", "nf_log_syslog");

                ret = nf_logger_find_get(par->family, NF_LOG_TYPE_LOG);
        }

        return ret;
}

static void log_tg_destroy(const struct xt_tgdtor_param *par)
{
        nf_logger_put(par->family, NF_LOG_TYPE_LOG);
}

static struct xt_target log_tg_regs[] __read_mostly = {
        {
                .name           = "LOG",
                .family         = NFPROTO_IPV4,
                .target         = log_tg,
                .targetsize     = sizeof(struct xt_log_info),
                .checkentry     = log_tg_check,
                .destroy        = log_tg_destroy,
                .me             = THIS_MODULE,
        },
#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
        {
                .name           = "LOG",
                .family         = NFPROTO_IPV6,
                .target         = log_tg,
                .targetsize     = sizeof(struct xt_log_info),
                .checkentry     = log_tg_check,
                .destroy        = log_tg_destroy,
                .me             = THIS_MODULE,
        },
#endif
};

static int __init log_tg_init(void)
{
        return xt_register_targets(log_tg_regs, ARRAY_SIZE(log_tg_regs));
}

static void __exit log_tg_exit(void)
{
        xt_unregister_targets(log_tg_regs, ARRAY_SIZE(log_tg_regs));
}

module_init(log_tg_init);
module_exit(log_tg_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
MODULE_AUTHOR("Jan Rekorajski <baggins@pld.org.pl>");
MODULE_DESCRIPTION("Xtables: IPv4/IPv6 packet logging");
MODULE_ALIAS("ipt_LOG");
MODULE_ALIAS("ip6t_LOG");
MODULE_SOFTDEP("pre: nf_log_syslog");