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         if (skb->len > skb->dev->mtu)
  35                 kfree_skb(skb);
  36         else {
  37 #ifdef CONFIG_BRIDGE_NETFILTER
  38                 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
  39                 nf_bridge_maybe_copy_header(skb);
  40 #endif
  41                 skb_push(skb, ETH_HLEN);
  42
  43                 dev_queue_xmit(skb);
  44         }
  45
  46         return 0;
  47 }
  48
  49 int br_forward_finish(struct sk_buff *skb)
  50 {
  51         NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  52                         br_dev_queue_push_xmit);
  53
  54         return 0;
  55 }
  56
  57 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  58 {
  59         skb->dev = to->dev;
  60         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  61                         br_forward_finish);
  62 }
  63
  64 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  65 {
  66         struct net_device *indev;
  67
  68         indev = skb->dev;
  69         skb->dev = to->dev;
  70         skb->ip_summed = CHECKSUM_NONE;
  71
  72         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
  73                         br_forward_finish);
  74 }
  75
  76 /* called with rcu_read_lock */
  77 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  78 {
  79         if (should_deliver(to, skb)) {
  80                 __br_deliver(to, skb);
  81                 return;
  82         }
  83
  84         kfree_skb(skb);
  85 }
  86
  87 /* called with rcu_read_lock */
  88 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  89 {
  90         if (should_deliver(to, skb)) {
  91                 __br_forward(to, skb);
  92                 return;
  93         }
  94
  95         kfree_skb(skb);
  96 }
  97
  98 /* called under bridge lock */
  99 static void br_flood(struct net_bridge *br, struct sk_buff *skb, int clone,
 100         void (*__packet_hook)(const struct net_bridge_port *p,
 101                               struct sk_buff *skb))
 102 {
 103         struct net_bridge_port *p;
 104         struct net_bridge_port *prev;
 105
 106         if (clone) {
 107                 struct sk_buff *skb2;
 108
 109                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 110                         br->statistics.tx_dropped++;
 111                         return;
 112                 }
 113
 114                 skb = skb2;
 115         }
 116
 117         prev = NULL;
 118
 119         list_for_each_entry_rcu(p, &br->port_list, list) {
 120                 if (should_deliver(p, skb)) {
 121                         if (prev != NULL) {
 122                                 struct sk_buff *skb2;
 123
 124                                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 125                                         br->statistics.tx_dropped++;
 126                                         kfree_skb(skb);
 127                                         return;
 128                                 }
 129
 130                                 __packet_hook(prev, skb2);
 131                         }
 132
 133                         prev = p;
 134                 }
 135         }
 136
 137         if (prev != NULL) {
 138                 __packet_hook(prev, skb);
 139                 return;
 140         }
 141
 142         kfree_skb(skb);
 143 }
 144
 145
 146 /* called with rcu_read_lock */
 147 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, int clone)
 148 {
 149         br_flood(br, skb, clone, __br_deliver);
 150 }
 151
 152 /* called under bridge lock */
 153 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, int clone)
 154 {
 155         br_flood(br, skb, clone, __br_forward);
 156 }