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         /* drop mtu oversized packets except tso */
  35         if (skb->len > skb->dev->mtu && !skb_shinfo(skb)->tso_size)
  36                 kfree_skb(skb);
  37         else {
  38 #ifdef CONFIG_BRIDGE_NETFILTER
  39                 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
  40                 nf_bridge_maybe_copy_header(skb);
  41 #endif
  42                 skb_push(skb, ETH_HLEN);
  43
  44                 dev_queue_xmit(skb);
  45         }
  46
  47         return 0;
  48 }
  49
  50 int br_forward_finish(struct sk_buff *skb)
  51 {
  52         NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  53                         br_dev_queue_push_xmit);
  54
  55         return 0;
  56 }
  57
  58 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  59 {
  60         skb->dev = to->dev;
  61         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  62                         br_forward_finish);
  63 }
  64
  65 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  66 {
  67         struct net_device *indev;
  68
  69         indev = skb->dev;
  70         skb->dev = to->dev;
  71         skb->ip_summed = CHECKSUM_NONE;
  72
  73         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
  74                         br_forward_finish);
  75 }
  76
  77 /* called with rcu_read_lock */
  78 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  79 {
  80         if (should_deliver(to, skb)) {
  81                 __br_deliver(to, skb);
  82                 return;
  83         }
  84
  85         kfree_skb(skb);
  86 }
  87
  88 /* called with rcu_read_lock */
  89 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  90 {
  91         if (should_deliver(to, skb)) {
  92                 __br_forward(to, skb);
  93                 return;
  94         }
  95
  96         kfree_skb(skb);
  97 }
  98
  99 /* called under bridge lock */
 100 static void br_flood(struct net_bridge *br, struct sk_buff *skb, int clone,
 101         void (*__packet_hook)(const struct net_bridge_port *p,
 102                               struct sk_buff *skb))
 103 {
 104         struct net_bridge_port *p;
 105         struct net_bridge_port *prev;
 106
 107         if (clone) {
 108                 struct sk_buff *skb2;
 109
 110                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 111                         br->statistics.tx_dropped++;
 112                         return;
 113                 }
 114
 115                 skb = skb2;
 116         }
 117
 118         prev = NULL;
 119
 120         list_for_each_entry_rcu(p, &br->port_list, list) {
 121                 if (should_deliver(p, skb)) {
 122                         if (prev != NULL) {
 123                                 struct sk_buff *skb2;
 124
 125                                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 126                                         br->statistics.tx_dropped++;
 127                                         kfree_skb(skb);
 128                                         return;
 129                                 }
 130
 131                                 __packet_hook(prev, skb2);
 132                         }
 133
 134                         prev = p;
 135                 }
 136         }
 137
 138         if (prev != NULL) {
 139                 __packet_hook(prev, skb);
 140                 return;
 141         }
 142
 143         kfree_skb(skb);
 144 }
 145
 146
 147 /* called with rcu_read_lock */
 148 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, int clone)
 149 {
 150         br_flood(br, skb, clone, __br_deliver);
 151 }
 152
 153 /* called under bridge lock */
 154 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, int clone)
 155 {
 156         br_flood(br, skb, clone, __br_forward);
 157 }