net/bridge/br_input.c

   1 /*
   2  *      Handle incoming frames
   3  *      Linux ethernet bridge
   4  *
   5  *      Authors:
   6  *      Lennert Buytenhek               <buytenh@gnu.org>
   7  *
   8  *      $Id: br_input.c,v 1.10 2001/12/24 04:50:20 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/etherdevice.h>
  19 #include <linux/netfilter_bridge.h>
  20 #include "br_private.h"
  21
  22 /* Bridge group multicast address 802.1d (pg 51). */
  23 const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
  24
  25 static void br_pass_frame_up(struct net_bridge *br, struct sk_buff *skb)
  26 {
  27         struct net_device *indev;
  28
  29         br->statistics.rx_packets++;
  30         br->statistics.rx_bytes += skb->len;
  31
  32         indev = skb->dev;
  33         skb->dev = br->dev;
  34
  35         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
  36                 netif_receive_skb);
  37 }
  38
  39 /* note: already called with rcu_read_lock (preempt_disabled) */
  40 int br_handle_frame_finish(struct sk_buff *skb)
  41 {
  42         const unsigned char *dest = eth_hdr(skb)->h_dest;
  43         struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
  44         struct net_bridge *br;
  45         struct net_bridge_fdb_entry *dst;
  46         int passedup = 0;
  47
  48         if (!p || p->state == BR_STATE_DISABLED)
  49                 goto drop;
  50
  51         /* insert into forwarding database after filtering to avoid spoofing */
  52         br = p->br;
  53         br_fdb_update(br, p, eth_hdr(skb)->h_source);
  54
  55         if (p->state == BR_STATE_LEARNING)
  56                 goto drop;
  57
  58         if (br->dev->flags & IFF_PROMISC) {
  59                 struct sk_buff *skb2;
  60
  61                 skb2 = skb_clone(skb, GFP_ATOMIC);
  62                 if (skb2 != NULL) {
  63                         passedup = 1;
  64                         br_pass_frame_up(br, skb2);
  65                 }
  66         }
  67
  68         if (is_multicast_ether_addr(dest)) {
  69                 br_flood_forward(br, skb, !passedup);
  70                 if (!passedup)
  71                         br_pass_frame_up(br, skb);
  72                 goto out;
  73         }
  74
  75         dst = __br_fdb_get(br, dest);
  76         if (dst != NULL && dst->is_local) {
  77                 if (!passedup)
  78                         br_pass_frame_up(br, skb);
  79                 else
  80                         kfree_skb(skb);
  81                 goto out;
  82         }
  83
  84         if (dst != NULL) {
  85                 br_forward(dst->dst, skb);
  86                 goto out;
  87         }
  88
  89         br_flood_forward(br, skb, 0);
  90
  91 out:
  92         return 0;
  93 drop:
  94         kfree_skb(skb);
  95         goto out;
  96 }
  97
  98 /* note: already called with rcu_read_lock (preempt_disabled) */
  99 static int br_handle_local_finish(struct sk_buff *skb)
 100 {
 101         struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
 102
 103         if (p && p->state != BR_STATE_DISABLED)
 104                 br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
 105
 106         return 0;        /* process further */
 107 }
 108
 109 /* Does address match the link local multicast address.
 110  * 01:80:c2:00:00:0X
 111  */
 112 static inline int is_link_local(const unsigned char *dest)
 113 {
 114         return memcmp(dest, br_group_address, 5) == 0 && (dest[5] & 0xf0) == 0;
 115 }
 116
 117 /*
 118  * Called via br_handle_frame_hook.
 119  * Return 0 if *pskb should be processed furthur
 120  *        1 if *pskb is handled
 121  * note: already called with rcu_read_lock (preempt_disabled)
 122  */
 123 int br_handle_frame(struct net_bridge_port *p, struct sk_buff **pskb)
 124 {
 125         struct sk_buff *skb = *pskb;
 126         const unsigned char *dest = eth_hdr(skb)->h_dest;
 127
 128         if (p->state == BR_STATE_DISABLED)
 129                 goto err;
 130
 131         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 132                 goto err;
 133
 134         if (unlikely(is_link_local(dest))) {
 135                 skb->pkt_type = PACKET_HOST;
 136                 return NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
 137                                NULL, br_handle_local_finish) != 0;
 138         }
 139
 140         if (p->state == BR_STATE_FORWARDING || p->state == BR_STATE_LEARNING) {
 141                 if (br_should_route_hook) {
 142                         if (br_should_route_hook(pskb))
 143                                 return 0;
 144                         skb = *pskb;
 145                         dest = eth_hdr(skb)->h_dest;
 146                 }
 147
 148                 if (!compare_ether_addr(p->br->dev->dev_addr, dest))
 149                         skb->pkt_type = PACKET_HOST;
 150
 151                 NF_HOOK(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 152                         br_handle_frame_finish);
 153                 return 1;
 154         }
 155
 156 err:
 157         kfree_skb(skb);
 158         return 1;
 159 }