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 const unsigned char bridge_ula[6] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
  23
  24 static int br_pass_frame_up_finish(struct sk_buff *skb)
  25 {
  26         netif_receive_skb(skb);
  27         return 0;
  28 }
  29
  30 static void br_pass_frame_up(struct net_bridge *br, struct sk_buff *skb)
  31 {
  32         struct net_device *indev;
  33
  34         br->statistics.rx_packets++;
  35         br->statistics.rx_bytes += skb->len;
  36
  37         indev = skb->dev;
  38         skb->dev = br->dev;
  39
  40         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
  41                         br_pass_frame_up_finish);
  42 }
  43
  44 /* note: already called with rcu_read_lock (preempt_disabled) */
  45 int br_handle_frame_finish(struct sk_buff *skb)
  46 {
  47         const unsigned char *dest = eth_hdr(skb)->h_dest;
  48         struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
  49         struct net_bridge *br;
  50         struct net_bridge_fdb_entry *dst;
  51         int passedup = 0;
  52
  53         if (!p || p->state == BR_STATE_DISABLED)
  54                 goto drop;
  55
  56         /* insert into forwarding database after filtering to avoid spoofing */
  57         br = p->br;
  58         br_fdb_update(br, p, eth_hdr(skb)->h_source);
  59
  60         if (p->state == BR_STATE_LEARNING)
  61                 goto drop;
  62
  63         if (br->dev->flags & IFF_PROMISC) {
  64                 struct sk_buff *skb2;
  65
  66                 skb2 = skb_clone(skb, GFP_ATOMIC);
  67                 if (skb2 != NULL) {
  68                         passedup = 1;
  69                         br_pass_frame_up(br, skb2);
  70                 }
  71         }
  72
  73         if (is_multicast_ether_addr(dest)) {
  74                 br_flood_forward(br, skb, !passedup);
  75                 if (!passedup)
  76                         br_pass_frame_up(br, skb);
  77                 goto out;
  78         }
  79
  80         dst = __br_fdb_get(br, dest);
  81         if (dst != NULL && dst->is_local) {
  82                 if (!passedup)
  83                         br_pass_frame_up(br, skb);
  84                 else
  85                         kfree_skb(skb);
  86                 goto out;
  87         }
  88
  89         if (dst != NULL) {
  90                 br_forward(dst->dst, skb);
  91                 goto out;
  92         }
  93
  94         br_flood_forward(br, skb, 0);
  95
  96 out:
  97         return 0;
  98 drop:
  99         kfree_skb(skb);
 100         goto out;
 101 }
 102
 103 /*
 104  * Called via br_handle_frame_hook.
 105  * Return 0 if *pskb should be processed furthur
 106  *        1 if *pskb is handled
 107  * note: already called with rcu_read_lock (preempt_disabled)
 108  */
 109 int br_handle_frame(struct net_bridge_port *p, struct sk_buff **pskb)
 110 {
 111         struct sk_buff *skb = *pskb;
 112         const unsigned char *dest = eth_hdr(skb)->h_dest;
 113
 114         if (p->state == BR_STATE_DISABLED)
 115                 goto err;
 116
 117         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 118                 goto err;
 119
 120         if (p->br->stp_enabled &&
 121             !memcmp(dest, bridge_ula, 5) &&
 122             !(dest[5] & 0xF0)) {
 123                 if (!dest[5]) {
 124                         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
 125                                 NULL, br_stp_handle_bpdu);
 126                         return 1;
 127                 }
 128                 goto err;
 129         }
 130
 131         if (p->state == BR_STATE_FORWARDING || p->state == BR_STATE_LEARNING) {
 132                 if (br_should_route_hook) {
 133                         if (br_should_route_hook(pskb))
 134                                 return 0;
 135                         skb = *pskb;
 136                         dest = eth_hdr(skb)->h_dest;
 137                 }
 138
 139                 if (!compare_ether_addr(p->br->dev->dev_addr, dest))
 140                         skb->pkt_type = PACKET_HOST;
 141
 142                 NF_HOOK(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 143                         br_handle_frame_finish);
 144                 return 1;
 145         }
 146
 147 err:
 148         kfree_skb(skb);
 149         return 1;
 150 }