// SPDX-License-Identifier: GPL-2.0-only
/*
 * net/sched/em_ipset.c ipset ematch
 *
 * Copyright (c) 2012 Florian Westphal <fw@strlen.de>
 */

#include <linux/gfp.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <linux/netfilter/xt_set.h>
#include <linux/ipv6.h>
#include <net/ip.h>
#include <net/pkt_cls.h>

static int em_ipset_change(struct net *net, void *data, int data_len,
                           struct tcf_ematch *em)
{
        struct xt_set_info *set = data;
        ip_set_id_t index;

        if (data_len != sizeof(*set))
                return -EINVAL;

        index = ip_set_nfnl_get_byindex(net, set->index);
        if (index == IPSET_INVALID_ID)
                return -ENOENT;

        em->datalen = sizeof(*set);
        em->data = (unsigned long)kmemdup(data, em->datalen, GFP_KERNEL);
        if (em->data)
                return 0;

        ip_set_nfnl_put(net, index);
        return -ENOMEM;
}

static void em_ipset_destroy(struct tcf_ematch *em)
{
        const struct xt_set_info *set = (const void *) em->data;
        if (set) {
                ip_set_nfnl_put(em->net, set->index);
                kfree((void *) em->data);
        }
}

static int em_ipset_match(struct sk_buff *skb, struct tcf_ematch *em,
                          struct tcf_pkt_info *info)
{
        struct ip_set_adt_opt opt;
        struct xt_action_param acpar;
        const struct xt_set_info *set = (const void *) em->data;
        struct net_device *dev, *indev = NULL;
        struct nf_hook_state state = {
                .net    = em->net,
        };
        int ret, network_offset;

        switch (skb_protocol(skb, true)) {
        case htons(ETH_P_IP):
                state.pf = NFPROTO_IPV4;
                if (!pskb_network_may_pull(skb, sizeof(struct iphdr)))
                        return 0;
                acpar.thoff = ip_hdrlen(skb);
                break;
        case htons(ETH_P_IPV6):
                state.pf = NFPROTO_IPV6;
                if (!pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))
                        return 0;
                /* doesn't call ipv6_find_hdr() because ipset doesn't use thoff, yet */
                acpar.thoff = sizeof(struct ipv6hdr);
                break;
        default:
                return 0;
        }

        opt.family = state.pf;
        opt.dim = set->dim;
        opt.flags = set->flags;
        opt.cmdflags = 0;
        opt.ext.timeout = ~0u;

        network_offset = skb_network_offset(skb);
        skb_pull(skb, network_offset);

        dev = skb->dev;

        rcu_read_lock();

        if (skb->skb_iif)
                indev = dev_get_by_index_rcu(em->net, skb->skb_iif);

        state.in      = indev ? indev : dev;
        state.out     = dev;
        acpar.state   = &state;

        ret = ip_set_test(set->index, skb, &acpar, &opt);

        rcu_read_unlock();

        skb_push(skb, network_offset);
        return ret;
}

static struct tcf_ematch_ops em_ipset_ops = {
        .kind     = TCF_EM_IPSET,
        .change   = em_ipset_change,
        .destroy  = em_ipset_destroy,
        .match    = em_ipset_match,
        .owner    = THIS_MODULE,
        .link     = LIST_HEAD_INIT(em_ipset_ops.link)
};

static int __init init_em_ipset(void)
{
        return tcf_em_register(&em_ipset_ops);
}

static void __exit exit_em_ipset(void)
{
        tcf_em_unregister(&em_ipset_ops);
}

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
MODULE_DESCRIPTION("TC extended match for IP sets");

module_init(init_em_ipset);
module_exit(exit_em_ipset);

MODULE_ALIAS_TCF_EMATCH(TCF_EM_IPSET);