net/bridge/br_forward.c

   1 /*
   2  *      Forwarding decision
   3  *      Linux ethernet bridge
   4  *
   5  *      Authors:
   6  *      Lennert Buytenhek               <buytenh@gnu.org>
   7  *
   8  *      $Id: br_forward.c,v 1.4 2001/08/14 22:05:57 davem Exp $
   9  *
  10  *      This program is free software; you can redistribute it and/or
  11  *      modify it under the terms of the GNU General Public License
  12  *      as published by the Free Software Foundation; either version
  13  *      2 of the License, or (at your option) any later version.
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/netdevice.h>
  18 #include <linux/skbuff.h>
  19 #include <linux/netfilter_bridge.h>
  20 #include "br_private.h"
  21
  22 static inline int should_deliver(const struct net_bridge_port *p,
  23                                  const struct sk_buff *skb)
  24 {
  25         if (skb->dev == p->dev ||
  26             p->state != BR_STATE_FORWARDING)
  27                 return 0;
  28
  29         return 1;
  30 }
  31
  32 int br_dev_queue_push_xmit(struct sk_buff *skb)
  33 {
  34 #ifdef CONFIG_BRIDGE_NETFILTER
  35         /* ip_refrag calls ip_fragment, which doesn't copy the MAC header. */
  36         nf_bridge_maybe_copy_header(skb);
  37 #endif
  38         skb_push(skb, ETH_HLEN);
  39
  40         dev_queue_xmit(skb);
  41
  42         return 0;
  43 }
  44
  45 int br_forward_finish(struct sk_buff *skb)
  46 {
  47         NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  48                         br_dev_queue_push_xmit);
  49
  50         return 0;
  51 }
  52
  53 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  54 {
  55         skb->dev = to->dev;
  56 #ifdef CONFIG_NETFILTER_DEBUG
  57         skb->nf_debug = 0;
  58 #endif
  59         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  60                         br_forward_finish);
  61 }
  62
  63 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  64 {
  65         struct net_device *indev;
  66
  67         indev = skb->dev;
  68         skb->dev = to->dev;
  69         skb->ip_summed = CHECKSUM_NONE;
  70
  71         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
  72                         br_forward_finish);
  73 }
  74
  75 /* called with rcu_read_lock */
  76 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  77 {
  78         if (should_deliver(to, skb)) {
  79                 __br_deliver(to, skb);
  80                 return;
  81         }
  82
  83         kfree_skb(skb);
  84 }
  85
  86 /* called with rcu_read_lock */
  87 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  88 {
  89         if (should_deliver(to, skb)) {
  90                 __br_forward(to, skb);
  91                 return;
  92         }
  93
  94         kfree_skb(skb);
  95 }
  96
  97 /* called under bridge lock */
  98 static void br_flood(struct net_bridge *br, struct sk_buff *skb, int clone,
  99         void (*__packet_hook)(const struct net_bridge_port *p,
 100                               struct sk_buff *skb))
 101 {
 102         struct net_bridge_port *p;
 103         struct net_bridge_port *prev;
 104
 105         if (clone) {
 106                 struct sk_buff *skb2;
 107
 108                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 109                         br->statistics.tx_dropped++;
 110                         return;
 111                 }
 112
 113                 skb = skb2;
 114         }
 115
 116         prev = NULL;
 117
 118         list_for_each_entry_rcu(p, &br->port_list, list) {
 119                 if (should_deliver(p, skb)) {
 120                         if (prev != NULL) {
 121                                 struct sk_buff *skb2;
 122
 123                                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 124                                         br->statistics.tx_dropped++;
 125                                         kfree_skb(skb);
 126                                         return;
 127                                 }
 128
 129                                 __packet_hook(prev, skb2);
 130                         }
 131
 132                         prev = p;
 133                 }
 134         }
 135
 136         if (prev != NULL) {
 137                 __packet_hook(prev, skb);
 138                 return;
 139         }
 140
 141         kfree_skb(skb);
 142 }
 143
 144
 145 /* called with rcu_read_lock */
 146 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, int clone)
 147 {
 148         br_flood(br, skb, clone, __br_deliver);
 149 }
 150
 151 /* called under bridge lock */
 152 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, int clone)
 153 {
 154         br_flood(br, skb, clone, __br_forward);
 155 }