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