kernel/linux/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 #if defined(CONFIG_MIPS_BRCM)
  30         /*
  31          * Do not forward  any packets received from
  32          *  one WAN interface to other WAN interfaces in multiple PVC case
  33          * In the following condition, if a new interface is added, please
  34          * add the check to compare the first 3 chars from the name as
  35          * shown below. Using strcmp will be expensive in this path.
  36         */
  37         if ((skb->nfmark & FROM_WAN)  &&
  38             ((*(p->dev->name)    == 'n') &&
  39             (*(p->dev->name + 1) == 'a') &&
  40             (*(p->dev->name + 2) == 's')))
  41                 return 0;
  42 #endif
  43
  44         return 1;
  45 }
  46
  47 int br_dev_queue_push_xmit(struct sk_buff *skb)
  48 {
  49 #if defined(CONFIG_MIPS_BRCM)
  50         // Just to make it consistent with 2.4 so it will not surprise the customers.(Should be more intelligent.)
  51 #ifdef CONFIG_BRIDGE_NETFILTER
  52         /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
  53         nf_bridge_maybe_copy_header(skb);
  54 #endif
  55         skb_push(skb, ETH_HLEN);
  56
  57         dev_queue_xmit(skb);
  58 #else
  59         if (skb->len > skb->dev->mtu)
  60                 kfree_skb(skb);
  61         else {
  62 #ifdef CONFIG_BRIDGE_NETFILTER
  63                 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
  64                 nf_bridge_maybe_copy_header(skb);
  65 #endif
  66                 skb_push(skb, ETH_HLEN);
  67
  68                 dev_queue_xmit(skb);
  69         }
  70 #endif
  71
  72         return 0;
  73 }
  74
  75 int br_forward_finish(struct sk_buff *skb)
  76 {
  77         NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  78                         br_dev_queue_push_xmit);
  79
  80         return 0;
  81 }
  82
  83 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  84 {
  85         skb->dev = to->dev;
  86 #ifdef CONFIG_NETFILTER_DEBUG
  87         skb->nf_debug = 0;
  88 #endif
  89         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  90                         br_forward_finish);
  91 }
  92
  93 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  94 {
  95         struct net_device *indev;
  96
  97         indev = skb->dev;
  98         skb->dev = to->dev;
  99         skb->ip_summed = CHECKSUM_NONE;
 100
 101         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
 102                         br_forward_finish);
 103 }
 104
 105 /* called with rcu_read_lock */
 106 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 107 {
 108         if (should_deliver(to, skb)) {
 109                 __br_deliver(to, skb);
 110                 return;
 111         }
 112
 113         kfree_skb(skb);
 114 }
 115
 116 /* called with rcu_read_lock */
 117 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
 118 {
 119         if (should_deliver(to, skb)) {
 120                 __br_forward(to, skb);
 121                 return;
 122         }
 123
 124         kfree_skb(skb);
 125 }
 126
 127 /* called under bridge lock */
 128 static void br_flood(struct net_bridge *br, struct sk_buff *skb, int clone,
 129         void (*__packet_hook)(const struct net_bridge_port *p,
 130                               struct sk_buff *skb))
 131 {
 132         struct net_bridge_port *p;
 133         struct net_bridge_port *prev;
 134
 135         if (clone) {
 136                 struct sk_buff *skb2;
 137
 138                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 139                         br->statistics.tx_dropped++;
 140                         return;
 141                 }
 142
 143                 skb = skb2;
 144         }
 145
 146         prev = NULL;
 147
 148         list_for_each_entry_rcu(p, &br->port_list, list) {
 149                 if (should_deliver(p, skb)) {
 150                         if (prev != NULL) {
 151                                 struct sk_buff *skb2;
 152
 153                                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 154                                         br->statistics.tx_dropped++;
 155                                         kfree_skb(skb);
 156                                         return;
 157                                 }
 158
 159                                 __packet_hook(prev, skb2);
 160                         }
 161
 162                         prev = p;
 163                 }
 164         }
 165
 166         if (prev != NULL) {
 167                 __packet_hook(prev, skb);
 168                 return;
 169         }
 170
 171         kfree_skb(skb);
 172 }
 173
 174
 175 /* called with rcu_read_lock */
 176 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, int clone)
 177 {
 178         br_flood(br, skb, clone, __br_deliver);
 179 }
 180
 181 /* called under bridge lock */
 182 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, int clone)
 183 {
 184         br_flood(br, skb, clone, __br_forward);
 185 }