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         bool unicast = true;
  69         u16 vid = 0;
  70
  71         if (!p || p->state == BR_STATE_DISABLED)
  72                 goto drop;
  73
  74         if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb, &vid))
  75                 goto drop;
  76
  77         /* insert into forwarding database after filtering to avoid spoofing */
  78         br = p->br;
  79         if (p->flags & BR_LEARNING)
  80                 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid);
  81
  82         if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
  83             br_multicast_rcv(br, p, skb))
  84                 goto drop;
  85
  86         if (p->state == BR_STATE_LEARNING)
  87                 goto drop;
  88
  89         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
  90
  91         /* The packet skb2 goes to the local host (NULL to skip). */
  92         skb2 = NULL;
  93
  94         if (br->dev->flags & IFF_PROMISC)
  95                 skb2 = skb;
  96
  97         dst = NULL;
  98
  99         if (is_broadcast_ether_addr(dest)) {
 100                 skb2 = skb;
 101                 unicast = false;
 102         } else if (is_multicast_ether_addr(dest)) {
 103                 mdst = br_mdb_get(br, skb, vid);
 104                 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
 105                     br_multicast_querier_exists(br, eth_hdr(skb))) {
 106                         if ((mdst && mdst->mglist) ||
 107                             br_multicast_is_router(br))
 108                                 skb2 = skb;
 109                         br_multicast_forward(mdst, skb, skb2);
 110                         skb = NULL;
 111                         if (!skb2)
 112                                 goto out;
 113                 } else
 114                         skb2 = skb;
 115
 116                 unicast = false;
 117                 br->dev->stats.multicast++;
 118         } else if ((dst = __br_fdb_get(br, dest, vid)) &&
 119                         dst->is_local) {
 120                 skb2 = skb;
 121                 /* Do not forward the packet since it's local. */
 122                 skb = NULL;
 123         }
 124
 125         if (skb) {
 126                 if (dst) {
 127                         dst->used = jiffies;
 128                         br_forward(dst->dst, skb, skb2);
 129                 } else
 130                         br_flood_forward(br, skb, skb2, unicast);
 131         }
 132
 133         if (skb2)
 134                 return br_pass_frame_up(skb2);
 135
 136 out:
 137         return 0;
 138 drop:
 139         kfree_skb(skb);
 140         goto out;
 141 }
 142
 143 /* note: already called with rcu_read_lock */
 144 static int br_handle_local_finish(struct sk_buff *skb)
 145 {
 146         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
 147         u16 vid = 0;
 148
 149         br_vlan_get_tag(skb, &vid);
 150         if (p->flags & BR_LEARNING)
 151                 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid);
 152         return 0;        /* process further */
 153 }
 154
 155 /*
 156  * Return NULL if skb is handled
 157  * note: already called with rcu_read_lock
 158  */
 159 rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 160 {
 161         struct net_bridge_port *p;
 162         struct sk_buff *skb = *pskb;
 163         const unsigned char *dest = eth_hdr(skb)->h_dest;
 164         br_should_route_hook_t *rhook;
 165
 166         if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 167                 return RX_HANDLER_PASS;
 168
 169         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 170                 goto drop;
 171
 172         skb = skb_share_check(skb, GFP_ATOMIC);
 173         if (!skb)
 174                 return RX_HANDLER_CONSUMED;
 175
 176         p = br_port_get_rcu(skb->dev);
 177
 178         if (unlikely(is_link_local_ether_addr(dest))) {
 179                 /*
 180                  * See IEEE 802.1D Table 7-10 Reserved addresses
 181                  *
 182                  * Assignment                           Value
 183                  * Bridge Group Address         01-80-C2-00-00-00
 184                  * (MAC Control) 802.3          01-80-C2-00-00-01
 185                  * (Link Aggregation) 802.3     01-80-C2-00-00-02
 186                  * 802.1X PAE address           01-80-C2-00-00-03
 187                  *
 188                  * 802.1AB LLDP                 01-80-C2-00-00-0E
 189                  *
 190                  * Others reserved for future standardization
 191                  */
 192                 switch (dest[5]) {
 193                 case 0x00:      /* Bridge Group Address */
 194                         /* If STP is turned off,
 195                            then must forward to keep loop detection */
 196                         if (p->br->stp_enabled == BR_NO_STP)
 197                                 goto forward;
 198                         break;
 199
 200                 case 0x01:      /* IEEE MAC (Pause) */
 201                         goto drop;
 202
 203                 default:
 204                         /* Allow selective forwarding for most other protocols */
 205                         if (p->br->group_fwd_mask & (1u << dest[5]))
 206                                 goto forward;
 207                 }
 208
 209                 /* Deliver packet to local host only */
 210                 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
 211                             NULL, br_handle_local_finish)) {
 212                         return RX_HANDLER_CONSUMED; /* consumed by filter */
 213                 } else {
 214                         *pskb = skb;
 215                         return RX_HANDLER_PASS; /* continue processing */
 216                 }
 217         }
 218
 219 forward:
 220         switch (p->state) {
 221         case BR_STATE_FORWARDING:
 222                 rhook = rcu_dereference(br_should_route_hook);
 223                 if (rhook) {
 224                         if ((*rhook)(skb)) {
 225                                 *pskb = skb;
 226                                 return RX_HANDLER_PASS;
 227                         }
 228                         dest = eth_hdr(skb)->h_dest;
 229                 }
 230                 /* fall through */
 231         case BR_STATE_LEARNING:
 232                 if (ether_addr_equal(p->br->dev->dev_addr, dest))
 233                         skb->pkt_type = PACKET_HOST;
 234
 235                 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 236                         br_handle_frame_finish);
 237                 break;
 238         default:
 239 drop:
 240                 kfree_skb(skb);
 241         }
 242         return RX_HANDLER_CONSUMED;
 243 }