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
24 static 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
30 static void fake_redirect(struct dst_entry *dst, struct sock *sk,
31 struct sk_buff *skb)
32 {
33 }
34
35 static u32 *fake_cow_metrics(struct dst_entry *dst, unsigned long old)
36 {
37 return NULL;
38 }
39
40 static 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
47 static unsigned int fake_mtu(const struct dst_entry *dst)
48 {
49 return dst->dev->mtu;
50 }
51
52 static 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 */
68 static const u32 br_dst_default_metrics[RTAX_MAX] = {
69 [RTAX_MTU - 1] = 1500,
70 };
71
72 void br_netfilter_rtable_init(struct net_bridge *br)
73 {
74 struct rtable *rt = &br->fake_rtable;
75
76 rcuref_init(&rt->dst.__rcuref, 1);
77 rt->dst.dev = br->dev;
78 dst_init_metrics(&rt->dst, br_dst_default_metrics, true);
79 rt->dst.flags = DST_NOXFRM | DST_FAKE_RTABLE;
80 rt->dst.ops = &fake_dst_ops;
81 }
82
83 int __init br_nf_core_init(void)
84 {
85 return dst_entries_init(&fake_dst_ops);
86 }
87
88 void br_nf_core_fini(void)
89 {
90 dst_entries_destroy(&fake_dst_ops);
91 }
92
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