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         skb = br_handle_vlan(br, br_get_vlan_info(br), skb);
  49         if (!skb)
  50                 return NET_RX_DROP;
  51
  52         indev = skb->dev;
  53         skb->dev = brdev;
  54
  55         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
  56                        netif_receive_skb);
  57 }
  58
  59 /* note: already called with rcu_read_lock */
  60 int br_handle_frame_finish(struct sk_buff *skb)
  61 {
  62         const unsigned char *dest = eth_hdr(skb)->h_dest;
  63         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
  64         struct net_bridge *br;
  65         struct net_bridge_fdb_entry *dst;
  66         struct net_bridge_mdb_entry *mdst;
  67         struct sk_buff *skb2;
  68         u16 vid = 0;
  69
  70         if (!p || p->state == BR_STATE_DISABLED)
  71                 goto drop;
  72
  73         if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb, &vid))
  74                 goto drop;
  75
  76         /* insert into forwarding database after filtering to avoid spoofing */
  77         br = p->br;
  78         br_fdb_update(br, p, eth_hdr(skb)->h_source, vid);
  79
  80         if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
  81             br_multicast_rcv(br, p, skb))
  82                 goto drop;
  83
  84         if (p->state == BR_STATE_LEARNING)
  85                 goto drop;
  86
  87         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
  88
  89         /* The packet skb2 goes to the local host (NULL to skip). */
  90         skb2 = NULL;
  91
  92         if (br->dev->flags & IFF_PROMISC)
  93                 skb2 = skb;
  94
  95         dst = NULL;
  96
  97         if (is_broadcast_ether_addr(dest))
  98                 skb2 = skb;
  99         else if (is_multicast_ether_addr(dest)) {
 100                 mdst = br_mdb_get(br, skb, vid);
 101                 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {
 102                         if ((mdst && mdst->mglist) ||
 103                             br_multicast_is_router(br))
 104                                 skb2 = skb;
 105                         br_multicast_forward(mdst, skb, skb2);
 106                         skb = NULL;
 107                         if (!skb2)
 108                                 goto out;
 109                 } else
 110                         skb2 = skb;
 111
 112                 br->dev->stats.multicast++;
 113         } else if ((dst = __br_fdb_get(br, dest, vid)) &&
 114                         dst->is_local) {
 115                 skb2 = skb;
 116                 /* Do not forward the packet since it's local. */
 117                 skb = NULL;
 118         }
 119
 120         if (skb) {
 121                 if (dst) {
 122                         dst->used = jiffies;
 123                         br_forward(dst->dst, skb, skb2);
 124                 } else
 125                         br_flood_forward(br, skb, skb2);
 126         }
 127
 128         if (skb2)
 129                 return br_pass_frame_up(skb2);
 130
 131 out:
 132         return 0;
 133 drop:
 134         kfree_skb(skb);
 135         goto out;
 136 }
 137
 138 /* note: already called with rcu_read_lock */
 139 static int br_handle_local_finish(struct sk_buff *skb)
 140 {
 141         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
 142         u16 vid = 0;
 143
 144         br_vlan_get_tag(skb, &vid);
 145         br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid);
 146         return 0;        /* process further */
 147 }
 148
 149 /*
 150  * Return NULL if skb is handled
 151  * note: already called with rcu_read_lock
 152  */
 153 rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 154 {
 155         struct net_bridge_port *p;
 156         struct sk_buff *skb = *pskb;
 157         const unsigned char *dest = eth_hdr(skb)->h_dest;
 158         br_should_route_hook_t *rhook;
 159
 160         if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 161                 return RX_HANDLER_PASS;
 162
 163         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 164                 goto drop;
 165
 166         skb = skb_share_check(skb, GFP_ATOMIC);
 167         if (!skb)
 168                 return RX_HANDLER_CONSUMED;
 169
 170         p = br_port_get_rcu(skb->dev);
 171
 172         if (unlikely(is_link_local_ether_addr(dest))) {
 173                 /*
 174                  * See IEEE 802.1D Table 7-10 Reserved addresses
 175                  *
 176                  * Assignment                           Value
 177                  * Bridge Group Address         01-80-C2-00-00-00
 178                  * (MAC Control) 802.3          01-80-C2-00-00-01
 179                  * (Link Aggregation) 802.3     01-80-C2-00-00-02
 180                  * 802.1X PAE address           01-80-C2-00-00-03
 181                  *
 182                  * 802.1AB LLDP                 01-80-C2-00-00-0E
 183                  *
 184                  * Others reserved for future standardization
 185                  */
 186                 switch (dest[5]) {
 187                 case 0x00:      /* Bridge Group Address */
 188                         /* If STP is turned off,
 189                            then must forward to keep loop detection */
 190                         if (p->br->stp_enabled == BR_NO_STP)
 191                                 goto forward;
 192                         break;
 193
 194                 case 0x01:      /* IEEE MAC (Pause) */
 195                         goto drop;
 196
 197                 default:
 198                         /* Allow selective forwarding for most other protocols */
 199                         if (p->br->group_fwd_mask & (1u << dest[5]))
 200                                 goto forward;
 201                 }
 202
 203                 /* Deliver packet to local host only */
 204                 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
 205                             NULL, br_handle_local_finish)) {
 206                         return RX_HANDLER_CONSUMED; /* consumed by filter */
 207                 } else {
 208                         *pskb = skb;
 209                         return RX_HANDLER_PASS; /* continue processing */
 210                 }
 211         }
 212
 213 forward:
 214         switch (p->state) {
 215         case BR_STATE_FORWARDING:
 216                 rhook = rcu_dereference(br_should_route_hook);
 217                 if (rhook) {
 218                         if ((*rhook)(skb)) {
 219                                 *pskb = skb;
 220                                 return RX_HANDLER_PASS;
 221                         }
 222                         dest = eth_hdr(skb)->h_dest;
 223                 }
 224                 /* fall through */
 225         case BR_STATE_LEARNING:
 226                 if (ether_addr_equal(p->br->dev->dev_addr, dest))
 227                         skb->pkt_type = PACKET_HOST;
 228
 229                 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 230                         br_handle_frame_finish);
 231                 break;
 232         default:
 233 drop:
 234                 kfree_skb(skb);
 235         }
 236         return RX_HANDLER_CONSUMED;
 237 }