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(ref: &rt->dst.__rcuref, cnt: 1);
73 rt->dst.dev = br->dev;
74 dst_init_metrics(dst: &rt->dst, src_metrics: br->metrics, read_only: false);
75 dst_metric_set(dst: &rt->dst, RTAX_MTU, val: 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(dst: &fake_dst_ops);
83}
84
85void br_nf_core_fini(void)
86{
87 dst_entries_destroy(dst: &fake_dst_ops);
88}
89

source code of linux/net/bridge/br_nf_core.c