br_nf_core.c

 1// SPDX-License-Identifier: GPL-2.0-or-later
 2/*
 3 *	Handle firewalling core
 4 *	Linux ethernet bridge
 5 *
 6 *	Authors:
 7 *	Lennert Buytenhek		<buytenh@gnu.org>
 8 *	Bart De Schuymer		<bdschuym@pandora.be>
 9 *
10 *	Lennert dedicates this file to Kerstin Wurdinger.
11 */
12
13#include <linux/module.h>
14#include <linux/kernel.h>
15#include <linux/in_route.h>
16#include <linux/inetdevice.h>
17#include <net/route.h>
18
19#include "br_private.h"
20#ifdef CONFIG_SYSCTL
21#include <linux/sysctl.h>
22#endif
23
24static void fake_update_pmtu(struct dst_entry *dst, struct sock *sk,
25			     struct sk_buff *skb, u32 mtu,
26			     bool confirm_neigh)
27{
28}
29
30static void fake_redirect(struct dst_entry *dst, struct sock *sk,
31			  struct sk_buff *skb)
32{
33}
34
35static u32 *fake_cow_metrics(struct dst_entry *dst, unsigned long old)
36{
37	return NULL;
38}
39
40static struct neighbour *fake_neigh_lookup(const struct dst_entry *dst,
41					   struct sk_buff *skb,
42					   const void *daddr)
43{
44	return NULL;
45}
46
47static unsigned int fake_mtu(const struct dst_entry *dst)
48{
49	return dst->dev->mtu;
50}
51
52static struct dst_ops fake_dst_ops = {
53	.family		= AF_INET,
54	.update_pmtu	= fake_update_pmtu,
55	.redirect	= fake_redirect,
56	.cow_metrics	= fake_cow_metrics,
57	.neigh_lookup	= fake_neigh_lookup,
58	.mtu		= fake_mtu,
59};
60
61/*
62 * Initialize bogus route table used to keep netfilter happy.
63 * Currently, we fill in the PMTU entry because netfilter
64 * refragmentation needs it, and the rt_flags entry because
65 * ipt_REJECT needs it.  Future netfilter modules might
66 * require us to fill additional fields.
67 */
68void br_netfilter_rtable_init(struct net_bridge *br)
69{
70	struct rtable *rt = &br->fake_rtable;
71
72	rcuref_init(&rt->dst.__rcuref, 1);
73	rt->dst.dev = br->dev;
74	dst_init_metrics(&rt->dst, br->metrics, false);
75	dst_metric_set(&rt->dst, RTAX_MTU, br->dev->mtu);
76	rt->dst.flags	= DST_NOXFRM | DST_FAKE_RTABLE;
77	rt->dst.ops = &fake_dst_ops;
78}
79
80int __init br_nf_core_init(void)
81{
82	return dst_entries_init(&fake_dst_ops);
83}
84
85void br_nf_core_fini(void)
86{
87	dst_entries_destroy(&fake_dst_ops);
88}