net/bridge/br_input.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      Handle incoming frames
   4  *      Linux ethernet bridge
   5  *
   6  *      Authors:
   7  *      Lennert Buytenhek               <buytenh@gnu.org>
   8  */
   9
  10 #include <linux/slab.h>
  11 #include <linux/kernel.h>
  12 #include <linux/netdevice.h>
  13 #include <linux/etherdevice.h>
  14 #include <linux/netfilter_bridge.h>
  15 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
  16 #include <net/netfilter/nf_queue.h>
  17 #endif
  18 #include <linux/neighbour.h>
  19 #include <net/arp.h>
  20 #include <net/dsa.h>
  21 #include <linux/export.h>
  22 #include <linux/rculist.h>
  23 #include "br_private.h"
  24 #include "br_private_tunnel.h"
  25
  26 static int
  27 br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
  28 {
  29         br_drop_fake_rtable(skb);
  30         return netif_receive_skb(skb);
  31 }
  32
  33 static int br_pass_frame_up(struct sk_buff *skb)
  34 {
  35         struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
  36         struct net_bridge *br = netdev_priv(brdev);
  37         struct net_bridge_vlan_group *vg;
  38
  39         dev_sw_netstats_rx_add(brdev, skb->len);
  40
  41         vg = br_vlan_group_rcu(br);
  42
  43         /* Reset the offload_fwd_mark because there could be a stacked
  44          * bridge above, and it should not think this bridge it doing
  45          * that bridge's work forwarding out its ports.
  46          */
  47         br_switchdev_frame_unmark(skb);
  48
  49         /* Bridge is just like any other port.  Make sure the
  50          * packet is allowed except in promisc mode when someone
  51          * may be running packet capture.
  52          */
  53         if (!(brdev->flags & IFF_PROMISC) &&
  54             !br_allowed_egress(vg, skb)) {
  55                 kfree_skb(skb);
  56                 return NET_RX_DROP;
  57         }
  58
  59         indev = skb->dev;
  60         skb->dev = brdev;
  61         skb = br_handle_vlan(br, NULL, vg, skb);
  62         if (!skb)
  63                 return NET_RX_DROP;
  64         /* update the multicast stats if the packet is IGMP/MLD */
  65         br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
  66                            BR_MCAST_DIR_TX);
  67
  68         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
  69                        dev_net(indev), NULL, skb, indev, NULL,
  70                        br_netif_receive_skb);
  71 }
  72
  73 /* note: already called with rcu_read_lock */
  74 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
  75 {
  76         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
  77         enum br_pkt_type pkt_type = BR_PKT_UNICAST;
  78         struct net_bridge_fdb_entry *dst = NULL;
  79         struct net_bridge_mcast_port *pmctx;
  80         struct net_bridge_mdb_entry *mdst;
  81         bool local_rcv, mcast_hit = false;
  82         struct net_bridge_mcast *brmctx;
  83         struct net_bridge_vlan *vlan;
  84         struct net_bridge *br;
  85         u16 vid = 0;
  86         u8 state;
  87
  88         if (!p)
  89                 goto drop;
  90
  91         br = p->br;
  92
  93         if (br_mst_is_enabled(br)) {
  94                 state = BR_STATE_FORWARDING;
  95         } else {
  96                 if (p->state == BR_STATE_DISABLED)
  97                         goto drop;
  98
  99                 state = p->state;
 100         }
 101
 102         brmctx = &p->br->multicast_ctx;
 103         pmctx = &p->multicast_ctx;
 104         if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid,
 105                                 &state, &vlan))
 106                 goto out;
 107
 108         if (p->flags & BR_PORT_LOCKED) {
 109                 struct net_bridge_fdb_entry *fdb_src =
 110                         br_fdb_find_rcu(br, eth_hdr(skb)->h_source, vid);
 111
 112                 if (!fdb_src || READ_ONCE(fdb_src->dst) != p ||
 113                     test_bit(BR_FDB_LOCAL, &fdb_src->flags))
 114                         goto drop;
 115         }
 116
 117         nbp_switchdev_frame_mark(p, skb);
 118
 119         /* insert into forwarding database after filtering to avoid spoofing */
 120         if (p->flags & BR_LEARNING)
 121                 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0);
 122
 123         local_rcv = !!(br->dev->flags & IFF_PROMISC);
 124         if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
 125                 /* by definition the broadcast is also a multicast address */
 126                 if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) {
 127                         pkt_type = BR_PKT_BROADCAST;
 128                         local_rcv = true;
 129                 } else {
 130                         pkt_type = BR_PKT_MULTICAST;
 131                         if (br_multicast_rcv(&brmctx, &pmctx, vlan, skb, vid))
 132                                 goto drop;
 133                 }
 134         }
 135
 136         if (state == BR_STATE_LEARNING)
 137                 goto drop;
 138
 139         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
 140         BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED);
 141
 142         if (IS_ENABLED(CONFIG_INET) &&
 143             (skb->protocol == htons(ETH_P_ARP) ||
 144              skb->protocol == htons(ETH_P_RARP))) {
 145                 br_do_proxy_suppress_arp(skb, br, vid, p);
 146         } else if (IS_ENABLED(CONFIG_IPV6) &&
 147                    skb->protocol == htons(ETH_P_IPV6) &&
 148                    br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
 149                    pskb_may_pull(skb, sizeof(struct ipv6hdr) +
 150                                  sizeof(struct nd_msg)) &&
 151                    ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
 152                         struct nd_msg *msg, _msg;
 153
 154                         msg = br_is_nd_neigh_msg(skb, &_msg);
 155                         if (msg)
 156                                 br_do_suppress_nd(skb, br, vid, p, msg);
 157         }
 158
 159         switch (pkt_type) {
 160         case BR_PKT_MULTICAST:
 161                 mdst = br_mdb_get(brmctx, skb, vid);
 162                 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
 163                     br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) {
 164                         if ((mdst && mdst->host_joined) ||
 165                             br_multicast_is_router(brmctx, skb)) {
 166                                 local_rcv = true;
 167                                 br->dev->stats.multicast++;
 168                         }
 169                         mcast_hit = true;
 170                 } else {
 171                         local_rcv = true;
 172                         br->dev->stats.multicast++;
 173                 }
 174                 break;
 175         case BR_PKT_UNICAST:
 176                 dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid);
 177                 break;
 178         default:
 179                 break;
 180         }
 181
 182         if (dst) {
 183                 unsigned long now = jiffies;
 184
 185                 if (test_bit(BR_FDB_LOCAL, &dst->flags))
 186                         return br_pass_frame_up(skb);
 187
 188                 if (now != dst->used)
 189                         dst->used = now;
 190                 br_forward(dst->dst, skb, local_rcv, false);
 191         } else {
 192                 if (!mcast_hit)
 193                         br_flood(br, skb, pkt_type, local_rcv, false);
 194                 else
 195                         br_multicast_flood(mdst, skb, brmctx, local_rcv, false);
 196         }
 197
 198         if (local_rcv)
 199                 return br_pass_frame_up(skb);
 200
 201 out:
 202         return 0;
 203 drop:
 204         kfree_skb(skb);
 205         goto out;
 206 }
 207 EXPORT_SYMBOL_GPL(br_handle_frame_finish);
 208
 209 static void __br_handle_local_finish(struct sk_buff *skb)
 210 {
 211         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
 212         u16 vid = 0;
 213
 214         /* check if vlan is allowed, to avoid spoofing */
 215         if ((p->flags & BR_LEARNING) &&
 216             nbp_state_should_learn(p) &&
 217             !br_opt_get(p->br, BROPT_NO_LL_LEARN) &&
 218             br_should_learn(p, skb, &vid))
 219                 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0);
 220 }
 221
 222 /* note: already called with rcu_read_lock */
 223 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 224 {
 225         __br_handle_local_finish(skb);
 226
 227         /* return 1 to signal the okfn() was called so it's ok to use the skb */
 228         return 1;
 229 }
 230
 231 static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb)
 232 {
 233 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 234         struct nf_hook_entries *e = NULL;
 235         struct nf_hook_state state;
 236         unsigned int verdict, i;
 237         struct net *net;
 238         int ret;
 239
 240         net = dev_net(skb->dev);
 241 #ifdef HAVE_JUMP_LABEL
 242         if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING]))
 243                 goto frame_finish;
 244 #endif
 245
 246         e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]);
 247         if (!e)
 248                 goto frame_finish;
 249
 250         nf_hook_state_init(&state, NF_BR_PRE_ROUTING,
 251                            NFPROTO_BRIDGE, skb->dev, NULL, NULL,
 252                            net, br_handle_frame_finish);
 253
 254         for (i = 0; i < e->num_hook_entries; i++) {
 255                 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state);
 256                 switch (verdict & NF_VERDICT_MASK) {
 257                 case NF_ACCEPT:
 258                         if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) {
 259                                 *pskb = skb;
 260                                 return RX_HANDLER_PASS;
 261                         }
 262                         break;
 263                 case NF_DROP:
 264                         kfree_skb(skb);
 265                         return RX_HANDLER_CONSUMED;
 266                 case NF_QUEUE:
 267                         ret = nf_queue(skb, &state, i, verdict);
 268                         if (ret == 1)
 269                                 continue;
 270                         return RX_HANDLER_CONSUMED;
 271                 default: /* STOLEN */
 272                         return RX_HANDLER_CONSUMED;
 273                 }
 274         }
 275 frame_finish:
 276         net = dev_net(skb->dev);
 277         br_handle_frame_finish(net, NULL, skb);
 278 #else
 279         br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
 280 #endif
 281         return RX_HANDLER_CONSUMED;
 282 }
 283
 284 /* Return 0 if the frame was not processed otherwise 1
 285  * note: already called with rcu_read_lock
 286  */
 287 static int br_process_frame_type(struct net_bridge_port *p,
 288                                  struct sk_buff *skb)
 289 {
 290         struct br_frame_type *tmp;
 291
 292         hlist_for_each_entry_rcu(tmp, &p->br->frame_type_list, list)
 293                 if (unlikely(tmp->type == skb->protocol))
 294                         return tmp->frame_handler(p, skb);
 295
 296         return 0;
 297 }
 298
 299 /*
 300  * Return NULL if skb is handled
 301  * note: already called with rcu_read_lock
 302  */
 303 static rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 304 {
 305         struct net_bridge_port *p;
 306         struct sk_buff *skb = *pskb;
 307         const unsigned char *dest = eth_hdr(skb)->h_dest;
 308
 309         if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 310                 return RX_HANDLER_PASS;
 311
 312         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 313                 goto drop;
 314
 315         skb = skb_share_check(skb, GFP_ATOMIC);
 316         if (!skb)
 317                 return RX_HANDLER_CONSUMED;
 318
 319         memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
 320
 321         p = br_port_get_rcu(skb->dev);
 322         if (p->flags & BR_VLAN_TUNNEL)
 323                 br_handle_ingress_vlan_tunnel(skb, p, nbp_vlan_group_rcu(p));
 324
 325         if (unlikely(is_link_local_ether_addr(dest))) {
 326                 u16 fwd_mask = p->br->group_fwd_mask_required;
 327
 328                 /*
 329                  * See IEEE 802.1D Table 7-10 Reserved addresses
 330                  *
 331                  * Assignment                           Value
 332                  * Bridge Group Address         01-80-C2-00-00-00
 333                  * (MAC Control) 802.3          01-80-C2-00-00-01
 334                  * (Link Aggregation) 802.3     01-80-C2-00-00-02
 335                  * 802.1X PAE address           01-80-C2-00-00-03
 336                  *
 337                  * 802.1AB LLDP                 01-80-C2-00-00-0E
 338                  *
 339                  * Others reserved for future standardization
 340                  */
 341                 fwd_mask |= p->group_fwd_mask;
 342                 switch (dest[5]) {
 343                 case 0x00:      /* Bridge Group Address */
 344                         /* If STP is turned off,
 345                            then must forward to keep loop detection */
 346                         if (p->br->stp_enabled == BR_NO_STP ||
 347                             fwd_mask & (1u << dest[5]))
 348                                 goto forward;
 349                         *pskb = skb;
 350                         __br_handle_local_finish(skb);
 351                         return RX_HANDLER_PASS;
 352
 353                 case 0x01:      /* IEEE MAC (Pause) */
 354                         goto drop;
 355
 356                 case 0x0E:      /* 802.1AB LLDP */
 357                         fwd_mask |= p->br->group_fwd_mask;
 358                         if (fwd_mask & (1u << dest[5]))
 359                                 goto forward;
 360                         *pskb = skb;
 361                         __br_handle_local_finish(skb);
 362                         return RX_HANDLER_PASS;
 363
 364                 default:
 365                         /* Allow selective forwarding for most other protocols */
 366                         fwd_mask |= p->br->group_fwd_mask;
 367                         if (fwd_mask & (1u << dest[5]))
 368                                 goto forward;
 369                 }
 370
 371                 /* The else clause should be hit when nf_hook():
 372                  *   - returns < 0 (drop/error)
 373                  *   - returns = 0 (stolen/nf_queue)
 374                  * Thus return 1 from the okfn() to signal the skb is ok to pass
 375                  */
 376                 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
 377                             dev_net(skb->dev), NULL, skb, skb->dev, NULL,
 378                             br_handle_local_finish) == 1) {
 379                         return RX_HANDLER_PASS;
 380                 } else {
 381                         return RX_HANDLER_CONSUMED;
 382                 }
 383         }
 384
 385         if (unlikely(br_process_frame_type(p, skb)))
 386                 return RX_HANDLER_PASS;
 387
 388 forward:
 389         if (br_mst_is_enabled(p->br))
 390                 goto defer_stp_filtering;
 391
 392         switch (p->state) {
 393         case BR_STATE_FORWARDING:
 394         case BR_STATE_LEARNING:
 395 defer_stp_filtering:
 396                 if (ether_addr_equal(p->br->dev->dev_addr, dest))
 397                         skb->pkt_type = PACKET_HOST;
 398
 399                 return nf_hook_bridge_pre(skb, pskb);
 400         default:
 401 drop:
 402                 kfree_skb(skb);
 403         }
 404         return RX_HANDLER_CONSUMED;
 405 }
 406
 407 /* This function has no purpose other than to appease the br_port_get_rcu/rtnl
 408  * helpers which identify bridged ports according to the rx_handler installed
 409  * on them (so there _needs_ to be a bridge rx_handler even if we don't need it
 410  * to do anything useful). This bridge won't support traffic to/from the stack,
 411  * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal
 412  * frames from the ETH_P_XDSA packet_type handler.
 413  */
 414 static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb)
 415 {
 416         return RX_HANDLER_PASS;
 417 }
 418
 419 rx_handler_func_t *br_get_rx_handler(const struct net_device *dev)
 420 {
 421         if (netdev_uses_dsa(dev))
 422                 return br_handle_frame_dummy;
 423
 424         return br_handle_frame;
 425 }
 426
 427 void br_add_frame(struct net_bridge *br, struct br_frame_type *ft)
 428 {
 429         hlist_add_head_rcu(&ft->list, &br->frame_type_list);
 430 }
 431
 432 void br_del_frame(struct net_bridge *br, struct br_frame_type *ft)
 433 {
 434         struct br_frame_type *tmp;
 435
 436         hlist_for_each_entry(tmp, &br->frame_type_list, list)
 437                 if (ft == tmp) {
 438                         hlist_del_rcu(&ft->list);
 439                         return;
 440                 }
 441 }