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