Pileus Git - ~andy/linux/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/slab.h>
  15 #include <linux/kernel.h>
  16 #include <linux/netdevice.h>
  17 #include <linux/etherdevice.h>
  18 #include <linux/netfilter_bridge.h>
  19 #include <linux/export.h>
  20 #include <linux/rculist.h>
  21 #include "br_private.h"
  22
  23 /* Hook for brouter */
  24 br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
  25 EXPORT_SYMBOL(br_should_route_hook);
  26
  27 static int br_pass_frame_up(struct sk_buff *skb)
  28 {
  29         struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
  30         struct net_bridge *br = netdev_priv(brdev);
  31         struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats);
  32
  33         u64_stats_update_begin(&brstats->syncp);
  34         brstats->rx_packets++;
  35         brstats->rx_bytes += skb->len;
  36         u64_stats_update_end(&brstats->syncp);
  37
  38         indev = skb->dev;
  39         skb->dev = brdev;
  40
  41         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
  42                        netif_receive_skb);
  43 }
  44
  45 /* note: already called with rcu_read_lock */
  46 int br_handle_frame_finish(struct sk_buff *skb)
  47 {
  48         const unsigned char *dest = eth_hdr(skb)->h_dest;
  49         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
  50         struct net_bridge *br;
  51         struct net_bridge_fdb_entry *dst;
  52         struct net_bridge_mdb_entry *mdst;
  53         struct sk_buff *skb2;
  54
  55         if (!p || p->state == BR_STATE_DISABLED)
  56                 goto drop;
  57
  58         if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb))
  59                 goto drop;
  60
  61         /* insert into forwarding database after filtering to avoid spoofing */
  62         br = p->br;
  63         br_fdb_update(br, p, eth_hdr(skb)->h_source);
  64
  65         if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
  66             br_multicast_rcv(br, p, skb))
  67                 goto drop;
  68
  69         if (p->state == BR_STATE_LEARNING)
  70                 goto drop;
  71
  72         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
  73
  74         /* The packet skb2 goes to the local host (NULL to skip). */
  75         skb2 = NULL;
  76
  77         if (br->dev->flags & IFF_PROMISC)
  78                 skb2 = skb;
  79
  80         dst = NULL;
  81
  82         if (is_broadcast_ether_addr(dest))
  83                 skb2 = skb;
  84         else if (is_multicast_ether_addr(dest)) {
  85                 mdst = br_mdb_get(br, skb);
  86                 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {
  87                         if ((mdst && mdst->mglist) ||
  88                             br_multicast_is_router(br))
  89                                 skb2 = skb;
  90                         br_multicast_forward(mdst, skb, skb2);
  91                         skb = NULL;
  92                         if (!skb2)
  93                                 goto out;
  94                 } else
  95                         skb2 = skb;
  96
  97                 br->dev->stats.multicast++;
  98         } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) {
  99                 skb2 = skb;
 100                 /* Do not forward the packet since it's local. */
 101                 skb = NULL;
 102         }
 103
 104         if (skb) {
 105                 if (dst) {
 106                         dst->used = jiffies;
 107                         br_forward(dst->dst, skb, skb2);
 108                 } else
 109                         br_flood_forward(br, skb, skb2);
 110         }
 111
 112         if (skb2)
 113                 return br_pass_frame_up(skb2);
 114
 115 out:
 116         return 0;
 117 drop:
 118         kfree_skb(skb);
 119         goto out;
 120 }
 121
 122 /* note: already called with rcu_read_lock */
 123 static int br_handle_local_finish(struct sk_buff *skb)
 124 {
 125         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
 126
 127         br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
 128         return 0;        /* process further */
 129 }
 130
 131 /*
 132  * Return NULL if skb is handled
 133  * note: already called with rcu_read_lock
 134  */
 135 rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 136 {
 137         struct net_bridge_port *p;
 138         struct sk_buff *skb = *pskb;
 139         const unsigned char *dest = eth_hdr(skb)->h_dest;
 140         br_should_route_hook_t *rhook;
 141
 142         if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 143                 return RX_HANDLER_PASS;
 144
 145         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 146                 goto drop;
 147
 148         skb = skb_share_check(skb, GFP_ATOMIC);
 149         if (!skb)
 150                 return RX_HANDLER_CONSUMED;
 151
 152         p = br_port_get_rcu(skb->dev);
 153
 154         if (unlikely(is_link_local_ether_addr(dest))) {
 155                 /*
 156                  * See IEEE 802.1D Table 7-10 Reserved addresses
 157                  *
 158                  * Assignment                           Value
 159                  * Bridge Group Address         01-80-C2-00-00-00
 160                  * (MAC Control) 802.3          01-80-C2-00-00-01
 161                  * (Link Aggregation) 802.3     01-80-C2-00-00-02
 162                  * 802.1X PAE address           01-80-C2-00-00-03
 163                  *
 164                  * 802.1AB LLDP                 01-80-C2-00-00-0E
 165                  *
 166                  * Others reserved for future standardization
 167                  */
 168                 switch (dest[5]) {
 169                 case 0x00:      /* Bridge Group Address */
 170                         /* If STP is turned off,
 171                            then must forward to keep loop detection */
 172                         if (p->br->stp_enabled == BR_NO_STP)
 173                                 goto forward;
 174                         break;
 175
 176                 case 0x01:      /* IEEE MAC (Pause) */
 177                         goto drop;
 178
 179                 default:
 180                         /* Allow selective forwarding for most other protocols */
 181                         if (p->br->group_fwd_mask & (1u << dest[5]))
 182                                 goto forward;
 183                 }
 184
 185                 /* Deliver packet to local host only */
 186                 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
 187                             NULL, br_handle_local_finish)) {
 188                         return RX_HANDLER_CONSUMED; /* consumed by filter */
 189                 } else {
 190                         *pskb = skb;
 191                         return RX_HANDLER_PASS; /* continue processing */
 192                 }
 193         }
 194
 195 forward:
 196         switch (p->state) {
 197         case BR_STATE_FORWARDING:
 198                 rhook = rcu_dereference(br_should_route_hook);
 199                 if (rhook) {
 200                         if ((*rhook)(skb)) {
 201                                 *pskb = skb;
 202                                 return RX_HANDLER_PASS;
 203                         }
 204                         dest = eth_hdr(skb)->h_dest;
 205                 }
 206                 /* fall through */
 207         case BR_STATE_LEARNING:
 208                 if (ether_addr_equal(p->br->dev->dev_addr, dest))
 209                         skb->pkt_type = PACKET_HOST;
 210
 211                 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 212                         br_handle_frame_finish);
 213                 break;
 214         default:
 215 drop:
 216                 kfree_skb(skb);
 217         }
 218         return RX_HANDLER_CONSUMED;
 219 }