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