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/if_vlan.h>
  20 #include <linux/netfilter_bridge.h>
  21 #include "br_private.h"
  22
  23 /* Don't forward packets to originating port or forwarding diasabled */
  24 static inline int should_deliver(const struct net_bridge_port *p,
  25                                  const struct sk_buff *skb)
  26 {
  27         return (skb->dev != p->dev && p->state == BR_STATE_FORWARDING);
  28 }
  29
  30 static inline unsigned packet_length(const struct sk_buff *skb)
  31 {
  32         return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
  33 }
  34
  35 int br_dev_queue_push_xmit(struct sk_buff *skb)
  36 {
  37         /* drop mtu oversized packets except gso */
  38         if (packet_length(skb) > skb->dev->mtu && !skb_shinfo(skb)->gso_size)
  39                 kfree_skb(skb);
  40         else {
  41 #ifdef CONFIG_BRIDGE_NETFILTER
  42                 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
  43                 nf_bridge_maybe_copy_header(skb);
  44 #endif
  45                 skb_push(skb, ETH_HLEN);
  46
  47                 dev_queue_xmit(skb);
  48         }
  49
  50         return 0;
  51 }
  52
  53 int br_forward_finish(struct sk_buff *skb)
  54 {
  55         return NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  56                        br_dev_queue_push_xmit);
  57
  58 }
  59
  60 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  61 {
  62         skb->dev = to->dev;
  63         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  64                         br_forward_finish);
  65 }
  66
  67 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  68 {
  69         struct net_device *indev;
  70
  71         indev = skb->dev;
  72         skb->dev = to->dev;
  73         skb->ip_summed = CHECKSUM_NONE;
  74
  75         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
  76                         br_forward_finish);
  77 }
  78
  79 /* called with rcu_read_lock */
  80 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  81 {
  82         if (should_deliver(to, skb)) {
  83                 __br_deliver(to, skb);
  84                 return;
  85         }
  86
  87         kfree_skb(skb);
  88 }
  89
  90 /* called with rcu_read_lock */
  91 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  92 {
  93         if (should_deliver(to, skb)) {
  94                 __br_forward(to, skb);
  95                 return;
  96         }
  97
  98         kfree_skb(skb);
  99 }
 100
 101 /* called under bridge lock */
 102 static void br_flood(struct net_bridge *br, struct sk_buff *skb, int clone,
 103         void (*__packet_hook)(const struct net_bridge_port *p,
 104                               struct sk_buff *skb))
 105 {
 106         struct net_bridge_port *p;
 107         struct net_bridge_port *prev;
 108
 109         if (clone) {
 110                 struct sk_buff *skb2;
 111
 112                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 113                         br->statistics.tx_dropped++;
 114                         return;
 115                 }
 116
 117                 skb = skb2;
 118         }
 119
 120         prev = NULL;
 121
 122         list_for_each_entry_rcu(p, &br->port_list, list) {
 123                 if (should_deliver(p, skb)) {
 124                         if (prev != NULL) {
 125                                 struct sk_buff *skb2;
 126
 127                                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 128                                         br->statistics.tx_dropped++;
 129                                         kfree_skb(skb);
 130                                         return;
 131                                 }
 132
 133                                 __packet_hook(prev, skb2);
 134                         }
 135
 136                         prev = p;
 137                 }
 138         }
 139
 140         if (prev != NULL) {
 141                 __packet_hook(prev, skb);
 142                 return;
 143         }
 144
 145         kfree_skb(skb);
 146 }
 147
 148
 149 /* called with rcu_read_lock */
 150 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, int clone)
 151 {
 152         br_flood(br, skb, clone, __br_deliver);
 153 }
 154
 155 /* called under bridge lock */
 156 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, int clone)
 157 {
 158         br_flood(br, skb, clone, __br_forward);
 159 }