// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      Handle firewalling core
 *      Linux ethernet bridge
 *
 *      Authors:
 *      Lennert Buytenhek               <buytenh@gnu.org>
 *      Bart De Schuymer                <bdschuym@pandora.be>
 *
 *      Lennert dedicates this file to Kerstin Wurdinger.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/in_route.h>
#include <linux/inetdevice.h>
#include <net/route.h>

#include "br_private.h"
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif

static void fake_update_pmtu(struct dst_entry *dst, struct sock *sk,
                             struct sk_buff *skb, u32 mtu,
                             bool confirm_neigh)
{
}

static void fake_redirect(struct dst_entry *dst, struct sock *sk,
                          struct sk_buff *skb)
{
}

static u32 *fake_cow_metrics(struct dst_entry *dst, unsigned long old)
{
        return NULL;
}

static struct neighbour *fake_neigh_lookup(const struct dst_entry *dst,
                                           struct sk_buff *skb,
                                           const void *daddr)
{
        return NULL;
}

static unsigned int fake_mtu(const struct dst_entry *dst)
{
        return dst->dev->mtu;
}

static struct dst_ops fake_dst_ops = {
        .family         = AF_INET,
        .update_pmtu    = fake_update_pmtu,
        .redirect       = fake_redirect,
        .cow_metrics    = fake_cow_metrics,
        .neigh_lookup   = fake_neigh_lookup,
        .mtu            = fake_mtu,
};

/*
 * Initialize bogus route table used to keep netfilter happy.
 * Currently, we fill in the PMTU entry because netfilter
 * refragmentation needs it, and the rt_flags entry because
 * ipt_REJECT needs it.  Future netfilter modules might
 * require us to fill additional fields.
 */
void br_netfilter_rtable_init(struct net_bridge *br)
{
        struct rtable *rt = &br->fake_rtable;

        rcuref_init(&rt->dst.__rcuref, 1);
        rt->dst.dev = br->dev;
        dst_init_metrics(&rt->dst, br->metrics, false);
        dst_metric_set(&rt->dst, RTAX_MTU, br->dev->mtu);
        rt->dst.flags   = DST_NOXFRM | DST_FAKE_RTABLE;
        rt->dst.ops = &fake_dst_ops;
}

int __init br_nf_core_init(void)
{
        return dst_entries_init(&fake_dst_ops);
}

void br_nf_core_fini(void)
{
        dst_entries_destroy(&fake_dst_ops);
}