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 || p->state == BR_STATE_DISABLED)
  89                 goto drop;
  90
  91         brmctx = &p->br->multicast_ctx;
  92         pmctx = &p->multicast_ctx;
  93         state = p->state;
  94         if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid,
  95                                 &state, &vlan))
  96                 goto out;
  97
  98         nbp_switchdev_frame_mark(p, skb);
  99
 100         /* insert into forwarding database after filtering to avoid spoofing */
 101         br = p->br;
 102         if (p->flags & BR_LEARNING)
 103                 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0);
 104
 105         local_rcv = !!(br->dev->flags & IFF_PROMISC);
 106         if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
 107                 /* by definition the broadcast is also a multicast address */
 108                 if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) {
 109                         pkt_type = BR_PKT_BROADCAST;
 110                         local_rcv = true;
 111                 } else {
 112                         pkt_type = BR_PKT_MULTICAST;
 113                         if (br_multicast_rcv(&brmctx, &pmctx, vlan, skb, vid))
 114                                 goto drop;
 115                 }
 116         }
 117
 118         if (state == BR_STATE_LEARNING)
 119                 goto drop;
 120
 121         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
 122         BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED);
 123
 124         if (IS_ENABLED(CONFIG_INET) &&
 125             (skb->protocol == htons(ETH_P_ARP) ||
 126              skb->protocol == htons(ETH_P_RARP))) {
 127                 br_do_proxy_suppress_arp(skb, br, vid, p);
 128         } else if (IS_ENABLED(CONFIG_IPV6) &&
 129                    skb->protocol == htons(ETH_P_IPV6) &&
 130                    br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
 131                    pskb_may_pull(skb, sizeof(struct ipv6hdr) +
 132                                  sizeof(struct nd_msg)) &&
 133                    ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
 134                         struct nd_msg *msg, _msg;
 135
 136                         msg = br_is_nd_neigh_msg(skb, &_msg);
 137                         if (msg)
 138                                 br_do_suppress_nd(skb, br, vid, p, msg);
 139         }
 140
 141         switch (pkt_type) {
 142         case BR_PKT_MULTICAST:
 143                 mdst = br_mdb_get(brmctx, skb, vid);
 144                 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
 145                     br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) {
 146                         if ((mdst && mdst->host_joined) ||
 147                             br_multicast_is_router(brmctx, skb)) {
 148                                 local_rcv = true;
 149                                 br->dev->stats.multicast++;
 150                         }
 151                         mcast_hit = true;
 152                 } else {
 153                         local_rcv = true;
 154                         br->dev->stats.multicast++;
 155                 }
 156                 break;
 157         case BR_PKT_UNICAST:
 158                 dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid);
 159                 break;
 160         default:
 161                 break;
 162         }
 163
 164         if (dst) {
 165                 unsigned long now = jiffies;
 166
 167                 if (test_bit(BR_FDB_LOCAL, &dst->flags))
 168                         return br_pass_frame_up(skb);
 169
 170                 if (now != dst->used)
 171                         dst->used = now;
 172                 br_forward(dst->dst, skb, local_rcv, false);
 173         } else {
 174                 if (!mcast_hit)
 175                         br_flood(br, skb, pkt_type, local_rcv, false);
 176                 else
 177                         br_multicast_flood(mdst, skb, brmctx, local_rcv, false);
 178         }
 179
 180         if (local_rcv)
 181                 return br_pass_frame_up(skb);
 182
 183 out:
 184         return 0;
 185 drop:
 186         kfree_skb(skb);
 187         goto out;
 188 }
 189 EXPORT_SYMBOL_GPL(br_handle_frame_finish);
 190
 191 static void __br_handle_local_finish(struct sk_buff *skb)
 192 {
 193         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
 194         u16 vid = 0;
 195
 196         /* check if vlan is allowed, to avoid spoofing */
 197         if ((p->flags & BR_LEARNING) &&
 198             nbp_state_should_learn(p) &&
 199             !br_opt_get(p->br, BROPT_NO_LL_LEARN) &&
 200             br_should_learn(p, skb, &vid))
 201                 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0);
 202 }
 203
 204 /* note: already called with rcu_read_lock */
 205 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 206 {
 207         __br_handle_local_finish(skb);
 208
 209         /* return 1 to signal the okfn() was called so it's ok to use the skb */
 210         return 1;
 211 }
 212
 213 static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb)
 214 {
 215 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 216         struct nf_hook_entries *e = NULL;
 217         struct nf_hook_state state;
 218         unsigned int verdict, i;
 219         struct net *net;
 220         int ret;
 221
 222         net = dev_net(skb->dev);
 223 #ifdef HAVE_JUMP_LABEL
 224         if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING]))
 225                 goto frame_finish;
 226 #endif
 227
 228         e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]);
 229         if (!e)
 230                 goto frame_finish;
 231
 232         nf_hook_state_init(&state, NF_BR_PRE_ROUTING,
 233                            NFPROTO_BRIDGE, skb->dev, NULL, NULL,
 234                            net, br_handle_frame_finish);
 235
 236         for (i = 0; i < e->num_hook_entries; i++) {
 237                 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state);
 238                 switch (verdict & NF_VERDICT_MASK) {
 239                 case NF_ACCEPT:
 240                         if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) {
 241                                 *pskb = skb;
 242                                 return RX_HANDLER_PASS;
 243                         }
 244                         break;
 245                 case NF_DROP:
 246                         kfree_skb(skb);
 247                         return RX_HANDLER_CONSUMED;
 248                 case NF_QUEUE:
 249                         ret = nf_queue(skb, &state, i, verdict);
 250                         if (ret == 1)
 251                                 continue;
 252                         return RX_HANDLER_CONSUMED;
 253                 default: /* STOLEN */
 254                         return RX_HANDLER_CONSUMED;
 255                 }
 256         }
 257 frame_finish:
 258         net = dev_net(skb->dev);
 259         br_handle_frame_finish(net, NULL, skb);
 260 #else
 261         br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
 262 #endif
 263         return RX_HANDLER_CONSUMED;
 264 }
 265
 266 /* Return 0 if the frame was not processed otherwise 1
 267  * note: already called with rcu_read_lock
 268  */
 269 static int br_process_frame_type(struct net_bridge_port *p,
 270                                  struct sk_buff *skb)
 271 {
 272         struct br_frame_type *tmp;
 273
 274         hlist_for_each_entry_rcu(tmp, &p->br->frame_type_list, list)
 275                 if (unlikely(tmp->type == skb->protocol))
 276                         return tmp->frame_handler(p, skb);
 277
 278         return 0;
 279 }
 280
 281 /*
 282  * Return NULL if skb is handled
 283  * note: already called with rcu_read_lock
 284  */
 285 static rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 286 {
 287         struct net_bridge_port *p;
 288         struct sk_buff *skb = *pskb;
 289         const unsigned char *dest = eth_hdr(skb)->h_dest;
 290
 291         if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 292                 return RX_HANDLER_PASS;
 293
 294         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 295                 goto drop;
 296
 297         skb = skb_share_check(skb, GFP_ATOMIC);
 298         if (!skb)
 299                 return RX_HANDLER_CONSUMED;
 300
 301         memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
 302
 303         p = br_port_get_rcu(skb->dev);
 304         if (p->flags & BR_VLAN_TUNNEL)
 305                 br_handle_ingress_vlan_tunnel(skb, p, nbp_vlan_group_rcu(p));
 306
 307         if (unlikely(is_link_local_ether_addr(dest))) {
 308                 u16 fwd_mask = p->br->group_fwd_mask_required;
 309
 310                 /*
 311                  * See IEEE 802.1D Table 7-10 Reserved addresses
 312                  *
 313                  * Assignment                           Value
 314                  * Bridge Group Address         01-80-C2-00-00-00
 315                  * (MAC Control) 802.3          01-80-C2-00-00-01
 316                  * (Link Aggregation) 802.3     01-80-C2-00-00-02
 317                  * 802.1X PAE address           01-80-C2-00-00-03
 318                  *
 319                  * 802.1AB LLDP                 01-80-C2-00-00-0E
 320                  *
 321                  * Others reserved for future standardization
 322                  */
 323                 fwd_mask |= p->group_fwd_mask;
 324                 switch (dest[5]) {
 325                 case 0x00:      /* Bridge Group Address */
 326                         /* If STP is turned off,
 327                            then must forward to keep loop detection */
 328                         if (p->br->stp_enabled == BR_NO_STP ||
 329                             fwd_mask & (1u << dest[5]))
 330                                 goto forward;
 331                         *pskb = skb;
 332                         __br_handle_local_finish(skb);
 333                         return RX_HANDLER_PASS;
 334
 335                 case 0x01:      /* IEEE MAC (Pause) */
 336                         goto drop;
 337
 338                 case 0x0E:      /* 802.1AB LLDP */
 339                         fwd_mask |= p->br->group_fwd_mask;
 340                         if (fwd_mask & (1u << dest[5]))
 341                                 goto forward;
 342                         *pskb = skb;
 343                         __br_handle_local_finish(skb);
 344                         return RX_HANDLER_PASS;
 345
 346                 default:
 347                         /* Allow selective forwarding for most other protocols */
 348                         fwd_mask |= p->br->group_fwd_mask;
 349                         if (fwd_mask & (1u << dest[5]))
 350                                 goto forward;
 351                 }
 352
 353                 /* The else clause should be hit when nf_hook():
 354                  *   - returns < 0 (drop/error)
 355                  *   - returns = 0 (stolen/nf_queue)
 356                  * Thus return 1 from the okfn() to signal the skb is ok to pass
 357                  */
 358                 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
 359                             dev_net(skb->dev), NULL, skb, skb->dev, NULL,
 360                             br_handle_local_finish) == 1) {
 361                         return RX_HANDLER_PASS;
 362                 } else {
 363                         return RX_HANDLER_CONSUMED;
 364                 }
 365         }
 366
 367         if (unlikely(br_process_frame_type(p, skb)))
 368                 return RX_HANDLER_PASS;
 369
 370 forward:
 371         switch (p->state) {
 372         case BR_STATE_FORWARDING:
 373         case BR_STATE_LEARNING:
 374                 if (ether_addr_equal(p->br->dev->dev_addr, dest))
 375                         skb->pkt_type = PACKET_HOST;
 376
 377                 return nf_hook_bridge_pre(skb, pskb);
 378         default:
 379 drop:
 380                 kfree_skb(skb);
 381         }
 382         return RX_HANDLER_CONSUMED;
 383 }
 384
 385 /* This function has no purpose other than to appease the br_port_get_rcu/rtnl
 386  * helpers which identify bridged ports according to the rx_handler installed
 387  * on them (so there _needs_ to be a bridge rx_handler even if we don't need it
 388  * to do anything useful). This bridge won't support traffic to/from the stack,
 389  * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal
 390  * frames from the ETH_P_XDSA packet_type handler.
 391  */
 392 static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb)
 393 {
 394         return RX_HANDLER_PASS;
 395 }
 396
 397 rx_handler_func_t *br_get_rx_handler(const struct net_device *dev)
 398 {
 399         if (netdev_uses_dsa(dev))
 400                 return br_handle_frame_dummy;
 401
 402         return br_handle_frame;
 403 }
 404
 405 void br_add_frame(struct net_bridge *br, struct br_frame_type *ft)
 406 {
 407         hlist_add_head_rcu(&ft->list, &br->frame_type_list);
 408 }
 409
 410 void br_del_frame(struct net_bridge *br, struct br_frame_type *ft)
 411 {
 412         struct br_frame_type *tmp;
 413
 414         hlist_for_each_entry(tmp, &br->frame_type_list, list)
 415                 if (ft == tmp) {
 416                         hlist_del_rcu(&ft->list);
 417                         return;
 418                 }
 419 }