SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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  *      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/etherdevice.h>
  17 #include <linux/netfilter_bridge.h>
  18 #include "br_private.h"
  19
  20 /* Bridge group multicast address 802.1d (pg 51). */
  21 const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
  22
  23 static int br_pass_frame_up(struct sk_buff *skb)
  24 {
  25         struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
  26         struct net_bridge *br = netdev_priv(brdev);
  27         struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats);
  28
  29         brstats->rx_packets++;
  30         brstats->rx_bytes += skb->len;
  31
  32         indev = skb->dev;
  33         skb->dev = brdev;
  34
  35         return 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         struct net_bridge_mdb_entry *mdst;
  47         struct sk_buff *skb2;
  48
  49         if (!p || p->state == BR_STATE_DISABLED)
  50                 goto drop;
  51
  52         /* insert into forwarding database after filtering to avoid spoofing */
  53         br = p->br;
  54         br_fdb_update(br, p, eth_hdr(skb)->h_source);
  55
  56         if (is_multicast_ether_addr(dest) &&
  57             br_multicast_rcv(br, p, skb))
  58                 goto drop;
  59
  60         if (p->state == BR_STATE_LEARNING)
  61                 goto drop;
  62
  63         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
  64
  65         /* The packet skb2 goes to the local host (NULL to skip). */
  66         skb2 = NULL;
  67
  68         if (br->dev->flags & IFF_PROMISC)
  69                 skb2 = skb;
  70
  71         dst = NULL;
  72
  73         if (is_multicast_ether_addr(dest)) {
  74                 mdst = br_mdb_get(br, skb);
  75                 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {
  76                         if ((mdst && !hlist_unhashed(&mdst->mglist)) ||
  77                             br_multicast_is_router(br))
  78                                 skb2 = skb;
  79                         br_multicast_forward(mdst, skb, skb2);
  80                         skb = NULL;
  81                         if (!skb2)
  82                                 goto out;
  83                 } else
  84                         skb2 = skb;
  85
  86                 br->dev->stats.multicast++;
  87         } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) {
  88                 skb2 = skb;
  89                 /* Do not forward the packet since it's local. */
  90                 skb = NULL;
  91         }
  92
  93         if (skb) {
  94                 if (dst)
  95                         br_forward(dst->dst, skb, skb2);
  96                 else
  97                         br_flood_forward(br, skb, skb2);
  98         }
  99
 100         if (skb2)
 101                 return br_pass_frame_up(skb2);
 102
 103 out:
 104         return 0;
 105 drop:
 106         kfree_skb(skb);
 107         goto out;
 108 }
 109
 110 /* note: already called with rcu_read_lock (preempt_disabled) */
 111 static int br_handle_local_finish(struct sk_buff *skb)
 112 {
 113         struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
 114
 115         if (p)
 116                 br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
 117         return 0;        /* process further */
 118 }
 119
 120 /* Does address match the link local multicast address.
 121  * 01:80:c2:00:00:0X
 122  */
 123 static inline int is_link_local(const unsigned char *dest)
 124 {
 125         __be16 *a = (__be16 *)dest;
 126         static const __be16 *b = (const __be16 *)br_group_address;
 127         static const __be16 m = cpu_to_be16(0xfff0);
 128
 129         return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0;
 130 }
 131
 132 /*
 133  * Called via br_handle_frame_hook.
 134  * Return NULL if skb is handled
 135  * note: already called with rcu_read_lock (preempt_disabled)
 136  */
 137 struct sk_buff *br_handle_frame(struct net_bridge_port *p, struct sk_buff *skb)
 138 {
 139         const unsigned char *dest = eth_hdr(skb)->h_dest;
 140         int (*rhook)(struct sk_buff *skb);
 141
 142         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 143                 goto drop;
 144
 145         skb = skb_share_check(skb, GFP_ATOMIC);
 146         if (!skb)
 147                 return NULL;
 148
 149         if (unlikely(is_link_local(dest))) {
 150                 /* Pause frames shouldn't be passed up by driver anyway */
 151                 if (skb->protocol == htons(ETH_P_PAUSE))
 152                         goto drop;
 153
 154                 /* If STP is turned off, then forward */
 155                 if (p->br->stp_enabled == BR_NO_STP && dest[5] == 0)
 156                         goto forward;
 157
 158                 if (NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
 159                             NULL, br_handle_local_finish))
 160                         return NULL;    /* frame consumed by filter */
 161                 else
 162                         return skb;     /* continue processing */
 163         }
 164
 165 forward:
 166         switch (p->state) {
 167         case BR_STATE_FORWARDING:
 168                 rhook = rcu_dereference(br_should_route_hook);
 169                 if (rhook != NULL) {
 170                         if (rhook(skb))
 171                                 return skb;
 172                         dest = eth_hdr(skb)->h_dest;
 173                 }
 174                 /* fall through */
 175         case BR_STATE_LEARNING:
 176                 if (!compare_ether_addr(p->br->dev->dev_addr, dest))
 177                         skb->pkt_type = PACKET_HOST;
 178
 179                 NF_HOOK(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 180                         br_handle_frame_finish);
 181                 break;
 182         default:
 183 drop:
 184                 kfree_skb(skb);
 185         }
 186         return NULL;
 187 }