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 { 27 } 28 29 static void fake_redirect(struct dst_entry *dst, struct sock *sk, 30 struct sk_buff *skb) 31 { 32 } 33 34 static u32 *fake_cow_metrics(struct dst_entry *dst, unsigned long old) 35 { 36 return NULL; 37 } 38 39 static struct neighbour *fake_neigh_lookup(const struct dst_entry *dst, 40 struct sk_buff *skb, 41 const void *daddr) 42 { 43 return NULL; 44 } 45 46 static unsigned int fake_mtu(const struct dst_entry *dst) 47 { 48 return dst->dev->mtu; 49 } 50 51 static struct dst_ops fake_dst_ops = { 52 .family = AF_INET, 53 .update_pmtu = fake_update_pmtu, 54 .redirect = fake_redirect, 55 .cow_metrics = fake_cow_metrics, 56 .neigh_lookup = fake_neigh_lookup, 57 .mtu = fake_mtu, 58 }; 59 60 /* 61 * Initialize bogus route table used to keep netfilter happy. 62 * Currently, we fill in the PMTU entry because netfilter 63 * refragmentation needs it, and the rt_flags entry because 64 * ipt_REJECT needs it. Future netfilter modules might 65 * require us to fill additional fields. 66 */ 67 static const u32 br_dst_default_metrics[RTAX_MAX] = { 68 [RTAX_MTU - 1] = 1500, 69 }; 70 71 void br_netfilter_rtable_init(struct net_bridge *br) 72 { 73 struct rtable *rt = &br->fake_rtable; 74 75 atomic_set(&rt->dst.__refcnt, 1); 76 rt->dst.dev = br->dev; 77 dst_init_metrics(&rt->dst, br_dst_default_metrics, true); 78 rt->dst.flags = DST_NOXFRM | DST_FAKE_RTABLE; 79 rt->dst.ops = &fake_dst_ops; 80 } 81 82 int __init br_nf_core_init(void) 83 { 84 return dst_entries_init(&fake_dst_ops); 85 } 86 87 void br_nf_core_fini(void) 88 { 89 dst_entries_destroy(&fake_dst_ops); 90 } 91