// SPDX-License-Identifier: GPL-2.0-only
/*
 * (C) 2013 Astaro GmbH & Co KG
 */

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

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
MODULE_DESCRIPTION("Xtables: add/match connection tracking labels");
MODULE_ALIAS("ipt_connlabel");
MODULE_ALIAS("ip6t_connlabel");

static bool
connlabel_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
        const struct xt_connlabel_mtinfo *info = par->matchinfo;
        enum ip_conntrack_info ctinfo;
        struct nf_conn_labels *labels;
        struct nf_conn *ct;
        bool invert = info->options & XT_CONNLABEL_OP_INVERT;

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

        labels = nf_ct_labels_find(ct);
        if (!labels)
                return invert;

        if (test_bit(info->bit, labels->bits))
                return !invert;

        if (info->options & XT_CONNLABEL_OP_SET) {
                if (!test_and_set_bit(info->bit, labels->bits))
                        nf_conntrack_event_cache(IPCT_LABEL, ct);

                return !invert;
        }

        return invert;
}

static int connlabel_mt_check(const struct xt_mtchk_param *par)
{
        const int options = XT_CONNLABEL_OP_INVERT |
                            XT_CONNLABEL_OP_SET;
        struct xt_connlabel_mtinfo *info = par->matchinfo;
        int ret;

        if (info->options & ~options) {
                pr_info_ratelimited("Unknown options in mask %x\n",
                                    info->options);
                return -EINVAL;
        }

        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;
        }

        ret = nf_connlabels_get(par->net, info->bit);
        if (ret < 0)
                nf_ct_netns_put(par->net, par->family);
        return ret;
}

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

static struct xt_match connlabels_mt_reg __read_mostly = {
        .name           = "connlabel",
        .family         = NFPROTO_UNSPEC,
        .checkentry     = connlabel_mt_check,
        .match          = connlabel_mt,
        .matchsize      = sizeof(struct xt_connlabel_mtinfo),
        .destroy        = connlabel_mt_destroy,
        .me             = THIS_MODULE,
};

static int __init connlabel_mt_init(void)
{
        return xt_register_match(&connlabels_mt_reg);
}

static void __exit connlabel_mt_exit(void)
{
        xt_unregister_match(&connlabels_mt_reg);
}

module_init(connlabel_mt_init);
module_exit(connlabel_mt_exit);