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 static inline int should_deliver(const struct net_bridge_port *p,
  24                                  const struct sk_buff *skb)
  25 {
  26         if (skb->dev == p->dev ||
  27             p->state != BR_STATE_FORWARDING)
  28                 return 0;
  29
  30         return 1;
  31 }
  32
  33 static inline unsigned packet_length(const struct sk_buff *skb)
  34 {
  35         return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
  36 }
  37
  38 int br_dev_queue_push_xmit(struct sk_buff *skb)
  39 {
  40         /* drop mtu oversized packets except tso */
  41         if (skb->len > skb->dev->mtu && !skb_is_gso(skb))
  42                 kfree_skb(skb);
  43         else {
  44 #ifdef CONFIG_BRIDGE_NETFILTER
  45                 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
  46                 if (nf_bridge_maybe_copy_header(skb))
  47                         kfree_skb(skb);
  48                 else
  49 #endif
  50                 {
  51                         skb_push(skb, ETH_HLEN);
  52
  53                         dev_queue_xmit(skb);
  54                 }
  55         }
  56
  57         return 0;
  58 }
  59
  60 int br_forward_finish(struct sk_buff *skb)
  61 {
  62         NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  63                         br_dev_queue_push_xmit);
  64
  65         return 0;
  66 }
  67
  68 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  69 {
  70         skb->dev = to->dev;
  71         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  72                         br_forward_finish);
  73 }
  74
  75 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  76 {
  77         struct net_device *indev;
  78
  79         indev = skb->dev;
  80         skb->dev = to->dev;
  81         skb->ip_summed = CHECKSUM_NONE;
  82
  83         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
  84                         br_forward_finish);
  85 }
  86
  87 /* called with rcu_read_lock */
  88 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  89 {
  90         if (should_deliver(to, skb)) {
  91                 __br_deliver(to, skb);
  92                 return;
  93         }
  94
  95         kfree_skb(skb);
  96 }
  97
  98 /* called with rcu_read_lock */
  99 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
 100 {
 101         if (should_deliver(to, skb)) {
 102                 __br_forward(to, skb);
 103                 return;
 104         }
 105
 106         kfree_skb(skb);
 107 }
 108
 109 /* called under bridge lock */
 110 static void br_flood(struct net_bridge *br, struct sk_buff *skb, int clone,
 111         void (*__packet_hook)(const struct net_bridge_port *p,
 112                               struct sk_buff *skb))
 113 {
 114         struct net_bridge_port *p;
 115         struct net_bridge_port *prev;
 116
 117         if (clone) {
 118                 struct sk_buff *skb2;
 119
 120                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 121                         br->statistics.tx_dropped++;
 122                         return;
 123                 }
 124
 125                 skb = skb2;
 126         }
 127
 128         prev = NULL;
 129
 130         list_for_each_entry_rcu(p, &br->port_list, list) {
 131                 if (should_deliver(p, skb)) {
 132                         if (prev != NULL) {
 133                                 struct sk_buff *skb2;
 134
 135                                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 136                                         br->statistics.tx_dropped++;
 137                                         kfree_skb(skb);
 138                                         return;
 139                                 }
 140
 141                                 __packet_hook(prev, skb2);
 142                         }
 143
 144                         prev = p;
 145                 }
 146         }
 147
 148         if (prev != NULL) {
 149                 __packet_hook(prev, skb);
 150                 return;
 151         }
 152
 153         kfree_skb(skb);
 154 }
 155
 156
 157 /* called with rcu_read_lock */
 158 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, int clone)
 159 {
 160         br_flood(br, skb, clone, __br_deliver);
 161 }
 162
 163 /* called under bridge lock */
 164 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, int clone)
 165 {
 166         br_flood(br, skb, clone, __br_forward);
 167 }