LXR linux/net/bridge/br

   1/*
   2 *      Forwarding decision
   3 *      Linux ethernet bridge
   4 *
   5 *      Authors:
   6 *      Lennert Buytenhek               <buytenh@gnu.org>
   7 *
   8 *      This program is free software; you can redistribute it and/or
   9 *      modify it under the terms of the GNU General Public License
  10 *      as published by the Free Software Foundation; either version
  11 *      2 of the License, or (at your option) any later version.
  12 */
  13
  14#include <linux/kernel.h>
  15#include <linux/netdevice.h>
  16#include <linux/skbuff.h>
  17#include <linux/if_vlan.h>
  18#include <linux/netfilter_bridge.h>
  19#include "br_private.h"
  20
  21/* Don't forward packets to originating port or forwarding diasabled */
  22static inline int should_deliver(const struct net_bridge_port *p,
  23                                 const struct sk_buff *skb)
  24{
  25        return (skb->dev != p->dev && p->state == BR_STATE_FORWARDING);
  26}
  27
  28static inline unsigned packet_length(const struct sk_buff *skb)
  29{
  30        return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
  31}
  32
  33int br_dev_queue_push_xmit(struct sk_buff *skb)
  34{
  35        /* drop mtu oversized packets except gso */
  36        if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
  37                kfree_skb(skb);
  38        else {
  39                /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
  40                if (nf_bridge_maybe_copy_header(skb))
  41                        kfree_skb(skb);
  42                else {
  43                        skb_push(skb, ETH_HLEN);
  44
  45                        dev_queue_xmit(skb);
  46                }
  47        }
  48
  49        return 0;
  50}
  51
  52int br_forward_finish(struct sk_buff *skb)
  53{
  54        return NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  55                       br_dev_queue_push_xmit);
  56
  57}
  58
  59static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  60{
  61        skb->dev = to->dev;
  62        NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  63                        br_forward_finish);
  64}
  65
  66static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  67{
  68        struct net_device *indev;
  69
  70        indev = skb->dev;
  71        skb->dev = to->dev;
  72        skb_forward_csum(skb);
  73
  74        NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
  75                        br_forward_finish);
  76}
  77
  78/* called with rcu_read_lock */
  79void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  80{
  81        if (should_deliver(to, skb)) {
  82                __br_deliver(to, skb);
  83                return;
  84        }
  85
  86        kfree_skb(skb);
  87}
  88
  89/* called with rcu_read_lock */
  90void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  91{
  92        if (!skb_warn_if_lro(skb) && should_deliver(to, skb)) {
  93                __br_forward(to, skb);
  94                return;
  95        }
  96
  97        kfree_skb(skb);
  98}
  99
 100/* called under bridge lock */
 101static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 102        void (*__packet_hook)(const struct net_bridge_port *p,
 103                              struct sk_buff *skb))
 104{
 105        struct net_bridge_port *p;
 106        struct net_bridge_port *prev;
 107
 108        prev = NULL;
 109
 110        list_for_each_entry_rcu(p, &br->port_list, list) {
 111                if (should_deliver(p, skb)) {
 112                        if (prev != NULL) {
 113                                struct sk_buff *skb2;
 114
 115                                if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 116                                        br->dev->stats.tx_dropped++;
 117                                        kfree_skb(skb);
 118                                        return;
 119                                }
 120
 121                                __packet_hook(prev, skb2);
 122                        }
 123
 124                        prev = p;
 125                }
 126        }
 127
 128        if (prev != NULL) {
 129                __packet_hook(prev, skb);
 130                return;
 131        }
 132
 133        kfree_skb(skb);
 134}
 135
 136
 137/* called with rcu_read_lock */
 138void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
 139{
 140        br_flood(br, skb, __br_deliver);
 141}
 142
 143/* called under bridge lock */
 144void br_flood_forward(struct net_bridge *br, struct sk_buff *skb)
 145{
 146        br_flood(br, skb, __br_forward);
 147}
 148