net/bridge/br_forward.c

   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 */
  22 static 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
  28 static 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
  33 int 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
  52 int 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
  59 static 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
  66 static 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 */
  79 void 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 */
  90 void 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 */
 101 static 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 */
 138 void 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 */
 144 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb)
 145 {
 146         br_flood(br, skb, __br_forward);
 147 }