net/bridge/br_nf_core.c

   1 /*
   2  *      Handle firewalling core
   3  *      Linux ethernet bridge
   4  *
   5  *      Authors:
   6  *      Lennert Buytenhek               <buytenh@gnu.org>
   7  *      Bart De Schuymer                <bdschuym@pandora.be>
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  *
  14  *      Lennert dedicates this file to Kerstin Wurdinger.
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/kernel.h>
  19 #include <linux/in_route.h>
  20 #include <linux/inetdevice.h>
  21 #include <net/route.h>
  22
  23 #include "br_private.h"
  24 #ifdef CONFIG_SYSCTL
  25 #include <linux/sysctl.h>
  26 #endif
  27
  28 static void fake_update_pmtu(struct dst_entry *dst, struct sock *sk,
  29                              struct sk_buff *skb, u32 mtu)
  30 {
  31 }
  32
  33 static void fake_redirect(struct dst_entry *dst, struct sock *sk,
  34                           struct sk_buff *skb)
  35 {
  36 }
  37
  38 static u32 *fake_cow_metrics(struct dst_entry *dst, unsigned long old)
  39 {
  40         return NULL;
  41 }
  42
  43 static struct neighbour *fake_neigh_lookup(const struct dst_entry *dst,
  44                                            struct sk_buff *skb,
  45                                            const void *daddr)
  46 {
  47         return NULL;
  48 }
  49
  50 static unsigned int fake_mtu(const struct dst_entry *dst)
  51 {
  52         return dst->dev->mtu;
  53 }
  54
  55 static struct dst_ops fake_dst_ops = {
  56         .family         = AF_INET,
  57         .update_pmtu    = fake_update_pmtu,
  58         .redirect       = fake_redirect,
  59         .cow_metrics    = fake_cow_metrics,
  60         .neigh_lookup   = fake_neigh_lookup,
  61         .mtu            = fake_mtu,
  62 };
  63
  64 /*
  65  * Initialize bogus route table used to keep netfilter happy.
  66  * Currently, we fill in the PMTU entry because netfilter
  67  * refragmentation needs it, and the rt_flags entry because
  68  * ipt_REJECT needs it.  Future netfilter modules might
  69  * require us to fill additional fields.
  70  */
  71 static const u32 br_dst_default_metrics[RTAX_MAX] = {
  72         [RTAX_MTU - 1] = 1500,
  73 };
  74
  75 void br_netfilter_rtable_init(struct net_bridge *br)
  76 {
  77         struct rtable *rt = &br->fake_rtable;
  78
  79         atomic_set(&rt->dst.__refcnt, 1);
  80         rt->dst.dev = br->dev;
  81         rt->dst.path = &rt->dst;
  82         dst_init_metrics(&rt->dst, br_dst_default_metrics, true);
  83         rt->dst.flags   = DST_NOXFRM | DST_FAKE_RTABLE;
  84         rt->dst.ops = &fake_dst_ops;
  85 }
  86
  87 int __init br_nf_core_init(void)
  88 {
  89         return dst_entries_init(&fake_dst_ops);
  90 }
  91
  92 void br_nf_core_fini(void)
  93 {
  94         dst_entries_destroy(&fake_dst_ops);
  95 }