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/neighbour.h>
  20 #include <net/arp.h>
  21 #include <linux/export.h>
  22 #include <linux/rculist.h>
  23 #include "br_private.h"
  24 #include "br_private_tunnel.h"
  25
  26 /* Hook for brouter */
  27 br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
  28 EXPORT_SYMBOL(br_should_route_hook);
  29
  30 static int
  31 br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
  32 {
  33         br_drop_fake_rtable(skb);
  34         return netif_receive_skb(skb);
  35 }
  36
  37 static int br_pass_frame_up(struct sk_buff *skb)
  38 {
  39         struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
  40         struct net_bridge *br = netdev_priv(brdev);
  41         struct net_bridge_vlan_group *vg;
  42         struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
  43
  44         u64_stats_update_begin(&brstats->syncp);
  45         brstats->rx_packets++;
  46         brstats->rx_bytes += skb->len;
  47         u64_stats_update_end(&brstats->syncp);
  48
  49         vg = br_vlan_group_rcu(br);
  50         /* Bridge is just like any other port.  Make sure the
  51          * packet is allowed except in promisc modue when someone
  52          * may be running packet capture.
  53          */
  54         if (!(brdev->flags & IFF_PROMISC) &&
  55             !br_allowed_egress(vg, skb)) {
  56                 kfree_skb(skb);
  57                 return NET_RX_DROP;
  58         }
  59
  60         indev = skb->dev;
  61         skb->dev = brdev;
  62         skb = br_handle_vlan(br, NULL, vg, skb);
  63         if (!skb)
  64                 return NET_RX_DROP;
  65         /* update the multicast stats if the packet is IGMP/MLD */
  66         br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
  67                            BR_MCAST_DIR_TX);
  68
  69         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
  70                        dev_net(indev), NULL, skb, indev, NULL,
  71                        br_netif_receive_skb);
  72 }
  73
  74 static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
  75                             u16 vid, struct net_bridge_port *p)
  76 {
  77         struct net_device *dev = br->dev;
  78         struct neighbour *n;
  79         struct arphdr *parp;
  80         u8 *arpptr, *sha;
  81         __be32 sip, tip;
  82
  83         BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
  84
  85         if ((dev->flags & IFF_NOARP) ||
  86             !pskb_may_pull(skb, arp_hdr_len(dev)))
  87                 return;
  88
  89         parp = arp_hdr(skb);
  90
  91         if (parp->ar_pro != htons(ETH_P_IP) ||
  92             parp->ar_op != htons(ARPOP_REQUEST) ||
  93             parp->ar_hln != dev->addr_len ||
  94             parp->ar_pln != 4)
  95                 return;
  96
  97         arpptr = (u8 *)parp + sizeof(struct arphdr);
  98         sha = arpptr;
  99         arpptr += dev->addr_len;        /* sha */
 100         memcpy(&sip, arpptr, sizeof(sip));
 101         arpptr += sizeof(sip);
 102         arpptr += dev->addr_len;        /* tha */
 103         memcpy(&tip, arpptr, sizeof(tip));
 104
 105         if (ipv4_is_loopback(tip) ||
 106             ipv4_is_multicast(tip))
 107                 return;
 108
 109         n = neigh_lookup(&arp_tbl, &tip, dev);
 110         if (n) {
 111                 struct net_bridge_fdb_entry *f;
 112
 113                 if (!(n->nud_state & NUD_VALID)) {
 114                         neigh_release(n);
 115                         return;
 116                 }
 117
 118                 f = br_fdb_find_rcu(br, n->ha, vid);
 119                 if (f && ((p->flags & BR_PROXYARP) ||
 120                           (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) {
 121                         arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip,
 122                                  sha, n->ha, sha);
 123                         BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
 124                 }
 125
 126                 neigh_release(n);
 127         }
 128 }
 129
 130 /* note: already called with rcu_read_lock */
 131 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 132 {
 133         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
 134         const unsigned char *dest = eth_hdr(skb)->h_dest;
 135         enum br_pkt_type pkt_type = BR_PKT_UNICAST;
 136         struct net_bridge_fdb_entry *dst = NULL;
 137         struct net_bridge_mdb_entry *mdst;
 138         bool local_rcv, mcast_hit = false;
 139         struct net_bridge *br;
 140         u16 vid = 0;
 141
 142         if (!p || p->state == BR_STATE_DISABLED)
 143                 goto drop;
 144
 145         if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid))
 146                 goto out;
 147
 148         nbp_switchdev_frame_mark(p, skb);
 149
 150         /* insert into forwarding database after filtering to avoid spoofing */
 151         br = p->br;
 152         if (p->flags & BR_LEARNING)
 153                 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);
 154
 155         local_rcv = !!(br->dev->flags & IFF_PROMISC);
 156         if (is_multicast_ether_addr(dest)) {
 157                 /* by definition the broadcast is also a multicast address */
 158                 if (is_broadcast_ether_addr(dest)) {
 159                         pkt_type = BR_PKT_BROADCAST;
 160                         local_rcv = true;
 161                 } else {
 162                         pkt_type = BR_PKT_MULTICAST;
 163                         if (br_multicast_rcv(br, p, skb, vid))
 164                                 goto drop;
 165                 }
 166         }
 167
 168         if (p->state == BR_STATE_LEARNING)
 169                 goto drop;
 170
 171         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
 172
 173         if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP))
 174                 br_do_proxy_arp(skb, br, vid, p);
 175
 176         switch (pkt_type) {
 177         case BR_PKT_MULTICAST:
 178                 mdst = br_mdb_get(br, skb, vid);
 179                 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
 180                     br_multicast_querier_exists(br, eth_hdr(skb))) {
 181                         if ((mdst && mdst->mglist) ||
 182                             br_multicast_is_router(br)) {
 183                                 local_rcv = true;
 184                                 br->dev->stats.multicast++;
 185                         }
 186                         mcast_hit = true;
 187                 } else {
 188                         local_rcv = true;
 189                         br->dev->stats.multicast++;
 190                 }
 191                 break;
 192         case BR_PKT_UNICAST:
 193                 dst = br_fdb_find_rcu(br, dest, vid);
 194         default:
 195                 break;
 196         }
 197
 198         if (dst) {
 199                 unsigned long now = jiffies;
 200
 201                 if (dst->is_local)
 202                         return br_pass_frame_up(skb);
 203
 204                 if (now != dst->used)
 205                         dst->used = now;
 206                 br_forward(dst->dst, skb, local_rcv, false);
 207         } else {
 208                 if (!mcast_hit)
 209                         br_flood(br, skb, pkt_type, local_rcv, false);
 210                 else
 211                         br_multicast_flood(mdst, skb, local_rcv, false);
 212         }
 213
 214         if (local_rcv)
 215                 return br_pass_frame_up(skb);
 216
 217 out:
 218         return 0;
 219 drop:
 220         kfree_skb(skb);
 221         goto out;
 222 }
 223 EXPORT_SYMBOL_GPL(br_handle_frame_finish);
 224
 225 static void __br_handle_local_finish(struct sk_buff *skb)
 226 {
 227         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
 228         u16 vid = 0;
 229
 230         /* check if vlan is allowed, to avoid spoofing */
 231         if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid))
 232                 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);
 233 }
 234
 235 /* note: already called with rcu_read_lock */
 236 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 237 {
 238         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
 239
 240         __br_handle_local_finish(skb);
 241
 242         BR_INPUT_SKB_CB(skb)->brdev = p->br->dev;
 243         br_pass_frame_up(skb);
 244         return 0;
 245 }
 246
 247 /*
 248  * Return NULL if skb is handled
 249  * note: already called with rcu_read_lock
 250  */
 251 rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 252 {
 253         struct net_bridge_port *p;
 254         struct sk_buff *skb = *pskb;
 255         const unsigned char *dest = eth_hdr(skb)->h_dest;
 256         br_should_route_hook_t *rhook;
 257
 258         if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 259                 return RX_HANDLER_PASS;
 260
 261         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 262                 goto drop;
 263
 264         skb = skb_share_check(skb, GFP_ATOMIC);
 265         if (!skb)
 266                 return RX_HANDLER_CONSUMED;
 267
 268         p = br_port_get_rcu(skb->dev);
 269         if (p->flags & BR_VLAN_TUNNEL) {
 270                 if (br_handle_ingress_vlan_tunnel(skb, p,
 271                                                   nbp_vlan_group_rcu(p)))
 272                         goto drop;
 273         }
 274
 275         if (unlikely(is_link_local_ether_addr(dest))) {
 276                 u16 fwd_mask = p->br->group_fwd_mask_required;
 277
 278                 /*
 279                  * See IEEE 802.1D Table 7-10 Reserved addresses
 280                  *
 281                  * Assignment                           Value
 282                  * Bridge Group Address         01-80-C2-00-00-00
 283                  * (MAC Control) 802.3          01-80-C2-00-00-01
 284                  * (Link Aggregation) 802.3     01-80-C2-00-00-02
 285                  * 802.1X PAE address           01-80-C2-00-00-03
 286                  *
 287                  * 802.1AB LLDP                 01-80-C2-00-00-0E
 288                  *
 289                  * Others reserved for future standardization
 290                  */
 291                 switch (dest[5]) {
 292                 case 0x00:      /* Bridge Group Address */
 293                         /* If STP is turned off,
 294                            then must forward to keep loop detection */
 295                         if (p->br->stp_enabled == BR_NO_STP ||
 296                             fwd_mask & (1u << dest[5]))
 297                                 goto forward;
 298                         *pskb = skb;
 299                         __br_handle_local_finish(skb);
 300                         return RX_HANDLER_PASS;
 301
 302                 case 0x01:      /* IEEE MAC (Pause) */
 303                         goto drop;
 304
 305                 case 0x0E:      /* 802.1AB LLDP */
 306                         fwd_mask |= p->br->group_fwd_mask;
 307                         if (fwd_mask & (1u << dest[5]))
 308                                 goto forward;
 309                         *pskb = skb;
 310                         __br_handle_local_finish(skb);
 311                         return RX_HANDLER_PASS;
 312
 313                 default:
 314                         /* Allow selective forwarding for most other protocols */
 315                         fwd_mask |= p->br->group_fwd_mask;
 316                         if (fwd_mask & (1u << dest[5]))
 317                                 goto forward;
 318                 }
 319
 320                 /* Deliver packet to local host only */
 321                 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev),
 322                         NULL, skb, skb->dev, NULL, br_handle_local_finish);
 323                 return RX_HANDLER_CONSUMED;
 324         }
 325
 326 forward:
 327         switch (p->state) {
 328         case BR_STATE_FORWARDING:
 329                 rhook = rcu_dereference(br_should_route_hook);
 330                 if (rhook) {
 331                         if ((*rhook)(skb)) {
 332                                 *pskb = skb;
 333                                 return RX_HANDLER_PASS;
 334                         }
 335                         dest = eth_hdr(skb)->h_dest;
 336                 }
 337                 /* fall through */
 338         case BR_STATE_LEARNING:
 339                 if (ether_addr_equal(p->br->dev->dev_addr, dest))
 340                         skb->pkt_type = PACKET_HOST;
 341
 342                 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING,
 343                         dev_net(skb->dev), NULL, skb, skb->dev, NULL,
 344                         br_handle_frame_finish);
 345                 break;
 346         default:
 347 drop:
 348                 kfree_skb(skb);
 349         }
 350         return RX_HANDLER_CONSUMED;
 351 }