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                 if (nf_bridge_maybe_copy_header(skb))
  41                         kfree_skb(skb);
  42                 else
  43 #endif
  44                 {
  45                         skb_push(skb, ETH_HLEN);
  46
  47                         dev_queue_xmit(skb);
  48                 }
  49         }
  50
  51         return 0;
  52 }
  53
  54 int br_forward_finish(struct sk_buff *skb)
  55 {
  56         NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  57                         br_dev_queue_push_xmit);
  58
  59         return 0;
  60 }
  61
  62 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  63 {
  64         skb->dev = to->dev;
  65         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  66                         br_forward_finish);
  67 }
  68
  69 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  70 {
  71         struct net_device *indev;
  72
  73         indev = skb->dev;
  74         skb->dev = to->dev;
  75         skb->ip_summed = CHECKSUM_NONE;
  76
  77         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
  78                         br_forward_finish);
  79 }
  80
  81 /* called with rcu_read_lock */
  82 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  83 {
  84         if (should_deliver(to, skb)) {
  85                 __br_deliver(to, skb);
  86                 return;
  87         }
  88
  89         kfree_skb(skb);
  90 }
  91
  92 /* called with rcu_read_lock */
  93 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  94 {
  95         if (should_deliver(to, skb)) {
  96                 __br_forward(to, skb);
  97                 return;
  98         }
  99
 100         kfree_skb(skb);
 101 }
 102
 103 /* called under bridge lock */
 104 static void br_flood(struct net_bridge *br, struct sk_buff *skb, int clone,
 105         void (*__packet_hook)(const struct net_bridge_port *p,
 106                               struct sk_buff *skb))
 107 {
 108         struct net_bridge_port *p;
 109         struct net_bridge_port *prev;
 110
 111         if (clone) {
 112                 struct sk_buff *skb2;
 113
 114                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 115                         br->statistics.tx_dropped++;
 116                         return;
 117                 }
 118
 119                 skb = skb2;
 120         }
 121
 122         prev = NULL;
 123
 124         list_for_each_entry_rcu(p, &br->port_list, list) {
 125                 if (should_deliver(p, skb)) {
 126                         if (prev != NULL) {
 127                                 struct sk_buff *skb2;
 128
 129                                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 130                                         br->statistics.tx_dropped++;
 131                                         kfree_skb(skb);
 132                                         return;
 133                                 }
 134
 135                                 __packet_hook(prev, skb2);
 136                         }
 137
 138                         prev = p;
 139                 }
 140         }
 141
 142         if (prev != NULL) {
 143                 __packet_hook(prev, skb);
 144                 return;
 145         }
 146
 147         kfree_skb(skb);
 148 }
 149
 150
 151 /* called with rcu_read_lock */
 152 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, int clone)
 153 {
 154         br_flood(br, skb, clone, __br_deliver);
 155 }
 156
 157 /* called under bridge lock */
 158 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, int clone)
 159 {
 160         br_flood(br, skb, clone, __br_forward);
 161 }