// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      xt_connmark - Netfilter module to operate on connection marks
 *
 *      Copyright (C) 2002,2004 MARA Systems AB <https://www.marasystems.com>
 *      by Henrik Nordstrom <hno@marasystems.com>
 *      Copyright © CC Computer Consultants GmbH, 2007 - 2008
 *      Jan Engelhardt <jengelh@medozas.de>
 */

#include <linux/module.h>
#include <linux/skbuff.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_connmark.h>

MODULE_AUTHOR("Henrik Nordstrom <hno@marasystems.com>");
MODULE_DESCRIPTION("Xtables: connection mark operations");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ipt_CONNMARK");
MODULE_ALIAS("ip6t_CONNMARK");
MODULE_ALIAS("ipt_connmark");
MODULE_ALIAS("ip6t_connmark");

static unsigned int
connmark_tg_shift(struct sk_buff *skb, const struct xt_connmark_tginfo2 *info)
{
        enum ip_conntrack_info ctinfo;
        u_int32_t new_targetmark;
        struct nf_conn *ct;
        u_int32_t newmark;
        u_int32_t oldmark;

        ct = nf_ct_get(skb, &ctinfo);
        if (ct == NULL)
                return XT_CONTINUE;

        switch (info->mode) {
        case XT_CONNMARK_SET:
                oldmark = READ_ONCE(ct->mark);
                newmark = (oldmark & ~info->ctmask) ^ info->ctmark;
                if (info->shift_dir == D_SHIFT_RIGHT)
                        newmark >>= info->shift_bits;
                else
                        newmark <<= info->shift_bits;

                if (READ_ONCE(ct->mark) != newmark) {
                        WRITE_ONCE(ct->mark, newmark);
                        nf_conntrack_event_cache(IPCT_MARK, ct);
                }
                break;
        case XT_CONNMARK_SAVE:
                new_targetmark = (skb->mark & info->nfmask);
                if (info->shift_dir == D_SHIFT_RIGHT)
                        new_targetmark >>= info->shift_bits;
                else
                        new_targetmark <<= info->shift_bits;

                newmark = (READ_ONCE(ct->mark) & ~info->ctmask) ^
                          new_targetmark;
                if (READ_ONCE(ct->mark) != newmark) {
                        WRITE_ONCE(ct->mark, newmark);
                        nf_conntrack_event_cache(IPCT_MARK, ct);
                }
                break;
        case XT_CONNMARK_RESTORE:
                new_targetmark = (READ_ONCE(ct->mark) & info->ctmask);
                if (info->shift_dir == D_SHIFT_RIGHT)
                        new_targetmark >>= info->shift_bits;
                else
                        new_targetmark <<= info->shift_bits;

                newmark = (skb->mark & ~info->nfmask) ^
                          new_targetmark;
                skb->mark = newmark;
                break;
        }
        return XT_CONTINUE;
}

static unsigned int
connmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
        const struct xt_connmark_tginfo1 *info = par->targinfo;
        const struct xt_connmark_tginfo2 info2 = {
                .ctmark = info->ctmark,
                .ctmask = info->ctmask,
                .nfmask = info->nfmask,
                .mode   = info->mode,
        };

        return connmark_tg_shift(skb, &info2);
}

static unsigned int
connmark_tg_v2(struct sk_buff *skb, const struct xt_action_param *par)
{
        const struct xt_connmark_tginfo2 *info = par->targinfo;

        return connmark_tg_shift(skb, info);
}

static int connmark_tg_check(const struct xt_tgchk_param *par)
{
        int ret;

        ret = nf_ct_netns_get(par->net, par->family);
        if (ret < 0)
                pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
                                    par->family);
        return ret;
}

static void connmark_tg_destroy(const struct xt_tgdtor_param *par)
{
        nf_ct_netns_put(par->net, par->family);
}

static bool
connmark_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
        const struct xt_connmark_mtinfo1 *info = par->matchinfo;
        enum ip_conntrack_info ctinfo;
        const struct nf_conn *ct;

        ct = nf_ct_get(skb, &ctinfo);
        if (ct == NULL)
                return false;

        return ((READ_ONCE(ct->mark) & info->mask) == info->mark) ^ info->invert;
}

static int connmark_mt_check(const struct xt_mtchk_param *par)
{
        int ret;

        ret = nf_ct_netns_get(par->net, par->family);
        if (ret < 0)
                pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
                                    par->family);
        return ret;
}

static void connmark_mt_destroy(const struct xt_mtdtor_param *par)
{
        nf_ct_netns_put(par->net, par->family);
}

static struct xt_target connmark_tg_reg[] __read_mostly = {
        {
                .name           = "CONNMARK",
                .revision       = 1,
                .family         = NFPROTO_IPV4,
                .checkentry     = connmark_tg_check,
                .target         = connmark_tg,
                .targetsize     = sizeof(struct xt_connmark_tginfo1),
                .destroy        = connmark_tg_destroy,
                .me             = THIS_MODULE,
        },
        {
                .name           = "CONNMARK",
                .revision       = 2,
                .family         = NFPROTO_IPV4,
                .checkentry     = connmark_tg_check,
                .target         = connmark_tg_v2,
                .targetsize     = sizeof(struct xt_connmark_tginfo2),
                .destroy        = connmark_tg_destroy,
                .me             = THIS_MODULE,
        },
#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
        {
                .name           = "CONNMARK",
                .revision       = 1,
                .family         = NFPROTO_IPV6,
                .checkentry     = connmark_tg_check,
                .target         = connmark_tg,
                .targetsize     = sizeof(struct xt_connmark_tginfo1),
                .destroy        = connmark_tg_destroy,
                .me             = THIS_MODULE,
        },
        {
                .name           = "CONNMARK",
                .revision       = 2,
                .family         = NFPROTO_IPV6,
                .checkentry     = connmark_tg_check,
                .target         = connmark_tg_v2,
                .targetsize     = sizeof(struct xt_connmark_tginfo2),
                .destroy        = connmark_tg_destroy,
                .me             = THIS_MODULE,
        },
#endif
};

static struct xt_match connmark_mt_reg __read_mostly = {
        .name           = "connmark",
        .revision       = 1,
        .family         = NFPROTO_UNSPEC,
        .checkentry     = connmark_mt_check,
        .match          = connmark_mt,
        .matchsize      = sizeof(struct xt_connmark_mtinfo1),
        .destroy        = connmark_mt_destroy,
        .me             = THIS_MODULE,
};

static int __init connmark_mt_init(void)
{
        int ret;

        ret = xt_register_targets(connmark_tg_reg,
                                  ARRAY_SIZE(connmark_tg_reg));
        if (ret < 0)
                return ret;
        ret = xt_register_match(&connmark_mt_reg);
        if (ret < 0) {
                xt_unregister_targets(connmark_tg_reg,
                                      ARRAY_SIZE(connmark_tg_reg));
                return ret;
        }
        return 0;
}

static void __exit connmark_mt_exit(void)
{
        xt_unregister_match(&connmark_mt_reg);
        xt_unregister_targets(connmark_tg_reg, ARRAY_SIZE(connmark_tg_reg));
}

module_init(connmark_mt_init);
module_exit(connmark_mt_exit);