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_is_gso(skb))
  39                 kfree_skb(skb);
  40         else {
  41                 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
  42                 if (nf_bridge_maybe_copy_header(skb))
  43                         kfree_skb(skb);
  44                 else {
  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         return NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  57                        br_dev_queue_push_xmit);
  58
  59 }
  60
  61 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  62 {
  63         skb->dev = to->dev;
  64         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  65                         br_forward_finish);
  66 }
  67
  68 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  69 {
  70         struct net_device *indev;
  71
  72         indev = skb->dev;
  73         skb->dev = to->dev;
  74         skb_forward_csum(skb);
  75
  76         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
  77                         br_forward_finish);
  78 }
  79
  80 /* called with rcu_read_lock */
  81 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  82 {
  83         if (should_deliver(to, skb)) {
  84                 __br_deliver(to, skb);
  85                 return;
  86         }
  87
  88         kfree_skb(skb);
  89 }
  90
  91 /* called with rcu_read_lock */
  92 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  93 {
  94         if (should_deliver(to, skb)) {
  95                 __br_forward(to, skb);
  96                 return;
  97         }
  98
  99         kfree_skb(skb);
 100 }
 101
 102 /* called under bridge lock */
 103 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 104         void (*__packet_hook)(const struct net_bridge_port *p,
 105                               struct sk_buff *skb))
 106 {
 107         struct net_bridge_port *p;
 108         struct net_bridge_port *prev;
 109
 110         prev = NULL;
 111
 112         list_for_each_entry_rcu(p, &br->port_list, list) {
 113                 if (should_deliver(p, skb)) {
 114                         if (prev != NULL) {
 115                                 struct sk_buff *skb2;
 116
 117                                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 118                                         br->dev->stats.tx_dropped++;
 119                                         kfree_skb(skb);
 120                                         return;
 121                                 }
 122
 123                                 __packet_hook(prev, skb2);
 124                         }
 125
 126                         prev = p;
 127                 }
 128         }
 129
 130         if (prev != NULL) {
 131                 __packet_hook(prev, skb);
 132                 return;
 133         }
 134
 135         kfree_skb(skb);
 136 }
 137
 138
 139 /* called with rcu_read_lock */
 140 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
 141 {
 142         br_flood(br, skb, __br_deliver);
 143 }
 144
 145 /* called under bridge lock */
 146 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb)
 147 {
 148         br_flood(br, skb, __br_forward);
 149 }