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