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) {
 113                         /* FDB miss. Create locked FDB entry if MAB is enabled
 114                          * and drop the packet.
 115                          */
 116                         if (p->flags & BR_PORT_MAB)
 117                                 br_fdb_update(br, p, eth_hdr(skb)->h_source,
 118                                               vid, BIT(BR_FDB_LOCKED));
 119                         goto drop;
 120                 } else if (READ_ONCE(fdb_src->dst) != p ||
 121                            test_bit(BR_FDB_LOCAL, &fdb_src->flags)) {
 122                         /* FDB mismatch. Drop the packet without roaming. */
 123                         goto drop;
 124                 } else if (test_bit(BR_FDB_LOCKED, &fdb_src->flags)) {
 125                         /* FDB match, but entry is locked. Refresh it and drop
 126                          * the packet.
 127                          */
 128                         br_fdb_update(br, p, eth_hdr(skb)->h_source, vid,
 129                                       BIT(BR_FDB_LOCKED));
 130                         goto drop;
 131                 }
 132         }
 133
 134         nbp_switchdev_frame_mark(p, skb);
 135
 136         /* insert into forwarding database after filtering to avoid spoofing */
 137         if (p->flags & BR_LEARNING)
 138                 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0);
 139
 140         local_rcv = !!(br->dev->flags & IFF_PROMISC);
 141         if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
 142                 /* by definition the broadcast is also a multicast address */
 143                 if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) {
 144                         pkt_type = BR_PKT_BROADCAST;
 145                         local_rcv = true;
 146                 } else {
 147                         pkt_type = BR_PKT_MULTICAST;
 148                         if (br_multicast_rcv(&brmctx, &pmctx, vlan, skb, vid))
 149                                 goto drop;
 150                 }
 151         }
 152
 153         if (state == BR_STATE_LEARNING)
 154                 goto drop;
 155
 156         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
 157         BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED);
 158
 159         if (IS_ENABLED(CONFIG_INET) &&
 160             (skb->protocol == htons(ETH_P_ARP) ||
 161              skb->protocol == htons(ETH_P_RARP))) {
 162                 br_do_proxy_suppress_arp(skb, br, vid, p);
 163         } else if (IS_ENABLED(CONFIG_IPV6) &&
 164                    skb->protocol == htons(ETH_P_IPV6) &&
 165                    br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
 166                    pskb_may_pull(skb, sizeof(struct ipv6hdr) +
 167                                  sizeof(struct nd_msg)) &&
 168                    ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
 169                         struct nd_msg *msg, _msg;
 170
 171                         msg = br_is_nd_neigh_msg(skb, &_msg);
 172                         if (msg)
 173                                 br_do_suppress_nd(skb, br, vid, p, msg);
 174         }
 175
 176         switch (pkt_type) {
 177         case BR_PKT_MULTICAST:
 178                 mdst = br_mdb_get(brmctx, skb, vid);
 179                 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
 180                     br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) {
 181                         if ((mdst && mdst->host_joined) ||
 182                             br_multicast_is_router(brmctx, skb)) {
 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, eth_hdr(skb)->h_dest, vid);
 194                 break;
 195         default:
 196                 break;
 197         }
 198
 199         if (dst) {
 200                 unsigned long now = jiffies;
 201
 202                 if (test_bit(BR_FDB_LOCAL, &dst->flags))
 203                         return br_pass_frame_up(skb);
 204
 205                 if (now != dst->used)
 206                         dst->used = now;
 207                 br_forward(dst->dst, skb, local_rcv, false);
 208         } else {
 209                 if (!mcast_hit)
 210                         br_flood(br, skb, pkt_type, local_rcv, false, vid);
 211                 else
 212                         br_multicast_flood(mdst, skb, brmctx, local_rcv, false);
 213         }
 214
 215         if (local_rcv)
 216                 return br_pass_frame_up(skb);
 217
 218 out:
 219         return 0;
 220 drop:
 221         kfree_skb(skb);
 222         goto out;
 223 }
 224 EXPORT_SYMBOL_GPL(br_handle_frame_finish);
 225
 226 static void __br_handle_local_finish(struct sk_buff *skb)
 227 {
 228         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
 229         u16 vid = 0;
 230
 231         /* check if vlan is allowed, to avoid spoofing */
 232         if ((p->flags & BR_LEARNING) &&
 233             nbp_state_should_learn(p) &&
 234             !br_opt_get(p->br, BROPT_NO_LL_LEARN) &&
 235             br_should_learn(p, skb, &vid))
 236                 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0);
 237 }
 238
 239 /* note: already called with rcu_read_lock */
 240 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 241 {
 242         __br_handle_local_finish(skb);
 243
 244         /* return 1 to signal the okfn() was called so it's ok to use the skb */
 245         return 1;
 246 }
 247
 248 static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb)
 249 {
 250 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 251         struct nf_hook_entries *e = NULL;
 252         struct nf_hook_state state;
 253         unsigned int verdict, i;
 254         struct net *net;
 255         int ret;
 256
 257         net = dev_net(skb->dev);
 258 #ifdef HAVE_JUMP_LABEL
 259         if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING]))
 260                 goto frame_finish;
 261 #endif
 262
 263         e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]);
 264         if (!e)
 265                 goto frame_finish;
 266
 267         nf_hook_state_init(&state, NF_BR_PRE_ROUTING,
 268                            NFPROTO_BRIDGE, skb->dev, NULL, NULL,
 269                            net, br_handle_frame_finish);
 270
 271         for (i = 0; i < e->num_hook_entries; i++) {
 272                 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state);
 273                 switch (verdict & NF_VERDICT_MASK) {
 274                 case NF_ACCEPT:
 275                         if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) {
 276                                 *pskb = skb;
 277                                 return RX_HANDLER_PASS;
 278                         }
 279                         break;
 280                 case NF_DROP:
 281                         kfree_skb(skb);
 282                         return RX_HANDLER_CONSUMED;
 283                 case NF_QUEUE:
 284                         ret = nf_queue(skb, &state, i, verdict);
 285                         if (ret == 1)
 286                                 continue;
 287                         return RX_HANDLER_CONSUMED;
 288                 default: /* STOLEN */
 289                         return RX_HANDLER_CONSUMED;
 290                 }
 291         }
 292 frame_finish:
 293         net = dev_net(skb->dev);
 294         br_handle_frame_finish(net, NULL, skb);
 295 #else
 296         br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
 297 #endif
 298         return RX_HANDLER_CONSUMED;
 299 }
 300
 301 /* Return 0 if the frame was not processed otherwise 1
 302  * note: already called with rcu_read_lock
 303  */
 304 static int br_process_frame_type(struct net_bridge_port *p,
 305                                  struct sk_buff *skb)
 306 {
 307         struct br_frame_type *tmp;
 308
 309         hlist_for_each_entry_rcu(tmp, &p->br->frame_type_list, list)
 310                 if (unlikely(tmp->type == skb->protocol))
 311                         return tmp->frame_handler(p, skb);
 312
 313         return 0;
 314 }
 315
 316 /*
 317  * Return NULL if skb is handled
 318  * note: already called with rcu_read_lock
 319  */
 320 static rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 321 {
 322         struct net_bridge_port *p;
 323         struct sk_buff *skb = *pskb;
 324         const unsigned char *dest = eth_hdr(skb)->h_dest;
 325
 326         if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 327                 return RX_HANDLER_PASS;
 328
 329         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 330                 goto drop;
 331
 332         skb = skb_share_check(skb, GFP_ATOMIC);
 333         if (!skb)
 334                 return RX_HANDLER_CONSUMED;
 335
 336         memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
 337
 338         p = br_port_get_rcu(skb->dev);
 339         if (p->flags & BR_VLAN_TUNNEL)
 340                 br_handle_ingress_vlan_tunnel(skb, p, nbp_vlan_group_rcu(p));
 341
 342         if (unlikely(is_link_local_ether_addr(dest))) {
 343                 u16 fwd_mask = p->br->group_fwd_mask_required;
 344
 345                 /*
 346                  * See IEEE 802.1D Table 7-10 Reserved addresses
 347                  *
 348                  * Assignment                           Value
 349                  * Bridge Group Address         01-80-C2-00-00-00
 350                  * (MAC Control) 802.3          01-80-C2-00-00-01
 351                  * (Link Aggregation) 802.3     01-80-C2-00-00-02
 352                  * 802.1X PAE address           01-80-C2-00-00-03
 353                  *
 354                  * 802.1AB LLDP                 01-80-C2-00-00-0E
 355                  *
 356                  * Others reserved for future standardization
 357                  */
 358                 fwd_mask |= p->group_fwd_mask;
 359                 switch (dest[5]) {
 360                 case 0x00:      /* Bridge Group Address */
 361                         /* If STP is turned off,
 362                            then must forward to keep loop detection */
 363                         if (p->br->stp_enabled == BR_NO_STP ||
 364                             fwd_mask & (1u << dest[5]))
 365                                 goto forward;
 366                         *pskb = skb;
 367                         __br_handle_local_finish(skb);
 368                         return RX_HANDLER_PASS;
 369
 370                 case 0x01:      /* IEEE MAC (Pause) */
 371                         goto drop;
 372
 373                 case 0x0E:      /* 802.1AB LLDP */
 374                         fwd_mask |= p->br->group_fwd_mask;
 375                         if (fwd_mask & (1u << dest[5]))
 376                                 goto forward;
 377                         *pskb = skb;
 378                         __br_handle_local_finish(skb);
 379                         return RX_HANDLER_PASS;
 380
 381                 default:
 382                         /* Allow selective forwarding for most other protocols */
 383                         fwd_mask |= p->br->group_fwd_mask;
 384                         if (fwd_mask & (1u << dest[5]))
 385                                 goto forward;
 386                 }
 387
 388                 /* The else clause should be hit when nf_hook():
 389                  *   - returns < 0 (drop/error)
 390                  *   - returns = 0 (stolen/nf_queue)
 391                  * Thus return 1 from the okfn() to signal the skb is ok to pass
 392                  */
 393                 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
 394                             dev_net(skb->dev), NULL, skb, skb->dev, NULL,
 395                             br_handle_local_finish) == 1) {
 396                         return RX_HANDLER_PASS;
 397                 } else {
 398                         return RX_HANDLER_CONSUMED;
 399                 }
 400         }
 401
 402         if (unlikely(br_process_frame_type(p, skb)))
 403                 return RX_HANDLER_PASS;
 404
 405 forward:
 406         if (br_mst_is_enabled(p->br))
 407                 goto defer_stp_filtering;
 408
 409         switch (p->state) {
 410         case BR_STATE_FORWARDING:
 411         case BR_STATE_LEARNING:
 412 defer_stp_filtering:
 413                 if (ether_addr_equal(p->br->dev->dev_addr, dest))
 414                         skb->pkt_type = PACKET_HOST;
 415
 416                 return nf_hook_bridge_pre(skb, pskb);
 417         default:
 418 drop:
 419                 kfree_skb(skb);
 420         }
 421         return RX_HANDLER_CONSUMED;
 422 }
 423
 424 /* This function has no purpose other than to appease the br_port_get_rcu/rtnl
 425  * helpers which identify bridged ports according to the rx_handler installed
 426  * on them (so there _needs_ to be a bridge rx_handler even if we don't need it
 427  * to do anything useful). This bridge won't support traffic to/from the stack,
 428  * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal
 429  * frames from the ETH_P_XDSA packet_type handler.
 430  */
 431 static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb)
 432 {
 433         return RX_HANDLER_PASS;
 434 }
 435
 436 rx_handler_func_t *br_get_rx_handler(const struct net_device *dev)
 437 {
 438         if (netdev_uses_dsa(dev))
 439                 return br_handle_frame_dummy;
 440
 441         return br_handle_frame;
 442 }
 443
 444 void br_add_frame(struct net_bridge *br, struct br_frame_type *ft)
 445 {
 446         hlist_add_head_rcu(&ft->list, &br->frame_type_list);
 447 }
 448
 449 void br_del_frame(struct net_bridge *br, struct br_frame_type *ft)
 450 {
 451         struct br_frame_type *tmp;
 452
 453         hlist_for_each_entry(tmp, &br->frame_type_list, list)
 454                 if (ft == tmp) {
 455                         hlist_del_rcu(&ft->list);
 456                         return;
 457                 }
 458 }