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         /* Bridge is just like any other port.  Make sure the
  39          * packet is allowed except in promisc modue when someone
  40          * may be running packet capture.
  41          */
  42         if (!(brdev->flags & IFF_PROMISC) &&
  43             !br_allowed_egress(br, br_get_vlan_info(br), skb)) {
  44                 kfree_skb(skb);
  45                 return NET_RX_DROP;
  46         }
  47
  48         indev = skb->dev;
  49         skb->dev = brdev;
  50
  51         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
  52                        netif_receive_skb);
  53 }
  54
  55 /* note: already called with rcu_read_lock */
  56 int br_handle_frame_finish(struct sk_buff *skb)
  57 {
  58         const unsigned char *dest = eth_hdr(skb)->h_dest;
  59         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
  60         struct net_bridge *br;
  61         struct net_bridge_fdb_entry *dst;
  62         struct net_bridge_mdb_entry *mdst;
  63         struct sk_buff *skb2;
  64
  65         if (!p || p->state == BR_STATE_DISABLED)
  66                 goto drop;
  67
  68         if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb))
  69                 goto drop;
  70
  71         /* insert into forwarding database after filtering to avoid spoofing */
  72         br = p->br;
  73         br_fdb_update(br, p, eth_hdr(skb)->h_source);
  74
  75         if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
  76             br_multicast_rcv(br, p, skb))
  77                 goto drop;
  78
  79         if (p->state == BR_STATE_LEARNING)
  80                 goto drop;
  81
  82         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
  83
  84         /* The packet skb2 goes to the local host (NULL to skip). */
  85         skb2 = NULL;
  86
  87         if (br->dev->flags & IFF_PROMISC)
  88                 skb2 = skb;
  89
  90         dst = NULL;
  91
  92         if (is_broadcast_ether_addr(dest))
  93                 skb2 = skb;
  94         else if (is_multicast_ether_addr(dest)) {
  95                 mdst = br_mdb_get(br, skb);
  96                 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {
  97                         if ((mdst && mdst->mglist) ||
  98                             br_multicast_is_router(br))
  99                                 skb2 = skb;
 100                         br_multicast_forward(mdst, skb, skb2);
 101                         skb = NULL;
 102                         if (!skb2)
 103                                 goto out;
 104                 } else
 105                         skb2 = skb;
 106
 107                 br->dev->stats.multicast++;
 108         } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) {
 109                 skb2 = skb;
 110                 /* Do not forward the packet since it's local. */
 111                 skb = NULL;
 112         }
 113
 114         if (skb) {
 115                 if (dst) {
 116                         dst->used = jiffies;
 117                         br_forward(dst->dst, skb, skb2);
 118                 } else
 119                         br_flood_forward(br, skb, skb2);
 120         }
 121
 122         if (skb2)
 123                 return br_pass_frame_up(skb2);
 124
 125 out:
 126         return 0;
 127 drop:
 128         kfree_skb(skb);
 129         goto out;
 130 }
 131
 132 /* note: already called with rcu_read_lock */
 133 static int br_handle_local_finish(struct sk_buff *skb)
 134 {
 135         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
 136
 137         br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
 138         return 0;        /* process further */
 139 }
 140
 141 /*
 142  * Return NULL if skb is handled
 143  * note: already called with rcu_read_lock
 144  */
 145 rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 146 {
 147         struct net_bridge_port *p;
 148         struct sk_buff *skb = *pskb;
 149         const unsigned char *dest = eth_hdr(skb)->h_dest;
 150         br_should_route_hook_t *rhook;
 151
 152         if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 153                 return RX_HANDLER_PASS;
 154
 155         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 156                 goto drop;
 157
 158         skb = skb_share_check(skb, GFP_ATOMIC);
 159         if (!skb)
 160                 return RX_HANDLER_CONSUMED;
 161
 162         p = br_port_get_rcu(skb->dev);
 163
 164         if (unlikely(is_link_local_ether_addr(dest))) {
 165                 /*
 166                  * See IEEE 802.1D Table 7-10 Reserved addresses
 167                  *
 168                  * Assignment                           Value
 169                  * Bridge Group Address         01-80-C2-00-00-00
 170                  * (MAC Control) 802.3          01-80-C2-00-00-01
 171                  * (Link Aggregation) 802.3     01-80-C2-00-00-02
 172                  * 802.1X PAE address           01-80-C2-00-00-03
 173                  *
 174                  * 802.1AB LLDP                 01-80-C2-00-00-0E
 175                  *
 176                  * Others reserved for future standardization
 177                  */
 178                 switch (dest[5]) {
 179                 case 0x00:      /* Bridge Group Address */
 180                         /* If STP is turned off,
 181                            then must forward to keep loop detection */
 182                         if (p->br->stp_enabled == BR_NO_STP)
 183                                 goto forward;
 184                         break;
 185
 186                 case 0x01:      /* IEEE MAC (Pause) */
 187                         goto drop;
 188
 189                 default:
 190                         /* Allow selective forwarding for most other protocols */
 191                         if (p->br->group_fwd_mask & (1u << dest[5]))
 192                                 goto forward;
 193                 }
 194
 195                 /* Deliver packet to local host only */
 196                 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
 197                             NULL, br_handle_local_finish)) {
 198                         return RX_HANDLER_CONSUMED; /* consumed by filter */
 199                 } else {
 200                         *pskb = skb;
 201                         return RX_HANDLER_PASS; /* continue processing */
 202                 }
 203         }
 204
 205 forward:
 206         switch (p->state) {
 207         case BR_STATE_FORWARDING:
 208                 rhook = rcu_dereference(br_should_route_hook);
 209                 if (rhook) {
 210                         if ((*rhook)(skb)) {
 211                                 *pskb = skb;
 212                                 return RX_HANDLER_PASS;
 213                         }
 214                         dest = eth_hdr(skb)->h_dest;
 215                 }
 216                 /* fall through */
 217         case BR_STATE_LEARNING:
 218                 if (ether_addr_equal(p->br->dev->dev_addr, dest))
 219                         skb->pkt_type = PACKET_HOST;
 220
 221                 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 222                         br_handle_frame_finish);
 223                 break;
 224         default:
 225 drop:
 226                 kfree_skb(skb);
 227         }
 228         return RX_HANDLER_CONSUMED;
 229 }