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 (((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
  26                 p->state == BR_STATE_FORWARDING);
  27 }
  28
  29 static inline unsigned packet_length(const struct sk_buff *skb)
  30 {
  31         return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
  32 }
  33
  34 int br_dev_queue_push_xmit(struct sk_buff *skb)
  35 {
  36         /* drop mtu oversized packets except gso */
  37         if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
  38                 kfree_skb(skb);
  39         else {
  40                 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
  41                 if (nf_bridge_maybe_copy_header(skb))
  42                         kfree_skb(skb);
  43                 else {
  44                         skb_push(skb, ETH_HLEN);
  45
  46                         dev_queue_xmit(skb);
  47                 }
  48         }
  49
  50         return 0;
  51 }
  52
  53 int br_forward_finish(struct sk_buff *skb)
  54 {
  55         return NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  56                        br_dev_queue_push_xmit);
  57
  58 }
  59
  60 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  61 {
  62         skb->dev = to->dev;
  63         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  64                         br_forward_finish);
  65 }
  66
  67 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  68 {
  69         struct net_device *indev;
  70
  71         if (skb_warn_if_lro(skb)) {
  72                 kfree_skb(skb);
  73                 return;
  74         }
  75
  76         indev = skb->dev;
  77         skb->dev = to->dev;
  78         skb_forward_csum(skb);
  79
  80         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
  81                         br_forward_finish);
  82 }
  83
  84 /* called with rcu_read_lock */
  85 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  86 {
  87         if (should_deliver(to, skb)) {
  88                 __br_deliver(to, skb);
  89                 return;
  90         }
  91
  92         kfree_skb(skb);
  93 }
  94
  95 /* called with rcu_read_lock */
  96 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  97 {
  98         if (should_deliver(to, skb)) {
  99                 __br_forward(to, skb);
 100                 return;
 101         }
 102
 103         kfree_skb(skb);
 104 }
 105
 106 /* called under bridge lock */
 107 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 108                      struct sk_buff *skb0,
 109                      void (*__packet_hook)(const struct net_bridge_port *p,
 110                                            struct sk_buff *skb))
 111 {
 112         struct net_bridge_port *p;
 113         struct net_bridge_port *prev;
 114         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 115
 116         prev = NULL;
 117
 118         list_for_each_entry_rcu(p, &br->port_list, list) {
 119                 if (should_deliver(p, skb)) {
 120                         if (prev != NULL) {
 121                                 struct sk_buff *skb2;
 122
 123                                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 124                                         dev->stats.tx_dropped++;
 125                                         goto out;
 126                                 }
 127
 128                                 __packet_hook(prev, skb2);
 129                         }
 130
 131                         prev = p;
 132                 }
 133         }
 134
 135         if (!prev)
 136                 goto out;
 137
 138         if (skb0) {
 139                 skb = skb_clone(skb, GFP_ATOMIC);
 140                 if (!skb) {
 141                         dev->stats.tx_dropped++;
 142                         goto out;
 143                 }
 144         }
 145         __packet_hook(prev, skb);
 146         return;
 147
 148 out:
 149         if (!skb0)
 150                 kfree_skb(skb);
 151 }
 152
 153
 154 /* called with rcu_read_lock */
 155 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
 156 {
 157         br_flood(br, skb, NULL, __br_deliver);
 158 }
 159
 160 /* called under bridge lock */
 161 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
 162                       struct sk_buff *skb2)
 163 {
 164         br_flood(br, skb, skb2, __br_forward);
 165 }