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, bool promisc) 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 BR_INPUT_SKB_CB(skb)->promisc = promisc; 69 70 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 71 dev_net(indev), NULL, skb, indev, NULL, 72 br_netif_receive_skb); 73 } 74 75 /* note: already called with rcu_read_lock */ 76 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 77 { 78 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 79 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 80 enum br_pkt_type pkt_type = BR_PKT_UNICAST; 81 struct net_bridge_fdb_entry *dst = NULL; 82 struct net_bridge_mcast_port *pmctx; 83 struct net_bridge_mdb_entry *mdst; 84 bool local_rcv, mcast_hit = false; 85 struct net_bridge_mcast *brmctx; 86 struct net_bridge_vlan *vlan; 87 struct net_bridge *br; 88 bool promisc; 89 u16 vid = 0; 90 u8 state; 91 92 if (!p) 93 goto drop; 94 95 br = p->br; 96 97 if (br_mst_is_enabled(br)) { 98 state = BR_STATE_FORWARDING; 99 } else { 100 if (p->state == BR_STATE_DISABLED) { 101 reason = SKB_DROP_REASON_BRIDGE_INGRESS_STP_STATE; 102 goto drop; 103 } 104 105 state = p->state; 106 } 107 108 brmctx = &p->br->multicast_ctx; 109 pmctx = &p->multicast_ctx; 110 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid, 111 &state, &vlan)) 112 goto out; 113 114 if (p->flags & BR_PORT_LOCKED) { 115 struct net_bridge_fdb_entry *fdb_src = 116 br_fdb_find_rcu(br, eth_hdr(skb)->h_source, vid); 117 118 if (!fdb_src) { 119 /* FDB miss. Create locked FDB entry if MAB is enabled 120 * and drop the packet. 121 */ 122 if (p->flags & BR_PORT_MAB) 123 br_fdb_update(br, p, eth_hdr(skb)->h_source, 124 vid, BIT(BR_FDB_LOCKED)); 125 goto drop; 126 } else if (READ_ONCE(fdb_src->dst) != p || 127 test_bit(BR_FDB_LOCAL, &fdb_src->flags)) { 128 /* FDB mismatch. Drop the packet without roaming. */ 129 goto drop; 130 } else if (test_bit(BR_FDB_LOCKED, &fdb_src->flags)) { 131 /* FDB match, but entry is locked. Refresh it and drop 132 * the packet. 133 */ 134 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 135 BIT(BR_FDB_LOCKED)); 136 goto drop; 137 } 138 } 139 140 nbp_switchdev_frame_mark(p, skb); 141 142 /* insert into forwarding database after filtering to avoid spoofing */ 143 if (p->flags & BR_LEARNING) 144 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0); 145 146 promisc = !!(br->dev->flags & IFF_PROMISC); 147 local_rcv = promisc; 148 149 if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) { 150 /* by definition the broadcast is also a multicast address */ 151 if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) { 152 pkt_type = BR_PKT_BROADCAST; 153 local_rcv = true; 154 } else { 155 pkt_type = BR_PKT_MULTICAST; 156 if (br_multicast_rcv(&brmctx, &pmctx, vlan, skb, vid)) 157 goto drop; 158 } 159 } 160 161 if (state == BR_STATE_LEARNING) { 162 reason = SKB_DROP_REASON_BRIDGE_INGRESS_STP_STATE; 163 goto drop; 164 } 165 166 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 167 BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED); 168 169 if (IS_ENABLED(CONFIG_INET) && 170 (skb->protocol == htons(ETH_P_ARP) || 171 skb->protocol == htons(ETH_P_RARP))) { 172 br_do_proxy_suppress_arp(skb, br, vid, p); 173 } else if (IS_ENABLED(CONFIG_IPV6) && 174 skb->protocol == htons(ETH_P_IPV6) && 175 br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) && 176 pskb_may_pull(skb, sizeof(struct ipv6hdr) + 177 sizeof(struct nd_msg)) && 178 ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) { 179 struct nd_msg *msg, _msg; 180 181 msg = br_is_nd_neigh_msg(skb, &_msg); 182 if (msg) 183 br_do_suppress_nd(skb, br, vid, p, msg); 184 } 185 186 switch (pkt_type) { 187 case BR_PKT_MULTICAST: 188 mdst = br_mdb_entry_skb_get(brmctx, skb, vid); 189 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 190 br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) { 191 if ((mdst && mdst->host_joined) || 192 br_multicast_is_router(brmctx, skb) || 193 br->dev->flags & IFF_ALLMULTI) { 194 local_rcv = true; 195 DEV_STATS_INC(br->dev, multicast); 196 } 197 mcast_hit = true; 198 } else { 199 local_rcv = true; 200 DEV_STATS_INC(br->dev, multicast); 201 } 202 break; 203 case BR_PKT_UNICAST: 204 dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid); 205 break; 206 default: 207 break; 208 } 209 210 if (dst) { 211 unsigned long now = jiffies; 212 213 if (test_bit(BR_FDB_LOCAL, &dst->flags)) 214 return br_pass_frame_up(skb, false); 215 216 if (now != dst->used) 217 dst->used = now; 218 br_forward(dst->dst, skb, local_rcv, false); 219 } else { 220 if (!mcast_hit) 221 br_flood(br, skb, pkt_type, local_rcv, false, vid); 222 else 223 br_multicast_flood(mdst, skb, brmctx, local_rcv, false); 224 } 225 226 if (local_rcv) 227 return br_pass_frame_up(skb, promisc); 228 229 out: 230 return 0; 231 drop: 232 kfree_skb_reason(skb, reason); 233 goto out; 234 } 235 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 236 237 static void __br_handle_local_finish(struct sk_buff *skb) 238 { 239 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 240 u16 vid = 0; 241 242 /* check if vlan is allowed, to avoid spoofing */ 243 if ((p->flags & BR_LEARNING) && 244 nbp_state_should_learn(p) && 245 !br_opt_get(p->br, BROPT_NO_LL_LEARN) && 246 br_should_learn(p, skb, &vid)) 247 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0); 248 } 249 250 /* note: already called with rcu_read_lock */ 251 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 252 { 253 __br_handle_local_finish(skb); 254 255 /* return 1 to signal the okfn() was called so it's ok to use the skb */ 256 return 1; 257 } 258 259 static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb) 260 { 261 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE 262 struct nf_hook_entries *e = NULL; 263 struct nf_hook_state state; 264 unsigned int verdict, i; 265 struct net *net; 266 int ret; 267 268 net = dev_net(skb->dev); 269 #ifdef HAVE_JUMP_LABEL 270 if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING])) 271 goto frame_finish; 272 #endif 273 274 e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]); 275 if (!e) 276 goto frame_finish; 277 278 nf_hook_state_init(&state, NF_BR_PRE_ROUTING, 279 NFPROTO_BRIDGE, skb->dev, NULL, NULL, 280 net, br_handle_frame_finish); 281 282 for (i = 0; i < e->num_hook_entries; i++) { 283 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state); 284 switch (verdict & NF_VERDICT_MASK) { 285 case NF_ACCEPT: 286 if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) { 287 *pskb = skb; 288 return RX_HANDLER_PASS; 289 } 290 break; 291 case NF_DROP: 292 kfree_skb(skb); 293 return RX_HANDLER_CONSUMED; 294 case NF_QUEUE: 295 ret = nf_queue(skb, &state, i, verdict); 296 if (ret == 1) 297 continue; 298 return RX_HANDLER_CONSUMED; 299 default: /* STOLEN */ 300 return RX_HANDLER_CONSUMED; 301 } 302 } 303 frame_finish: 304 net = dev_net(skb->dev); 305 br_handle_frame_finish(net, NULL, skb); 306 #else 307 br_handle_frame_finish(dev_net(skb->dev), NULL, skb); 308 #endif 309 return RX_HANDLER_CONSUMED; 310 } 311 312 /* Return 0 if the frame was not processed otherwise 1 313 * note: already called with rcu_read_lock 314 */ 315 static int br_process_frame_type(struct net_bridge_port *p, 316 struct sk_buff *skb) 317 { 318 struct br_frame_type *tmp; 319 320 hlist_for_each_entry_rcu(tmp, &p->br->frame_type_list, list) 321 if (unlikely(tmp->type == skb->protocol)) 322 return tmp->frame_handler(p, skb); 323 324 return 0; 325 } 326 327 /* 328 * Return NULL if skb is handled 329 * note: already called with rcu_read_lock 330 */ 331 static rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 332 { 333 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 334 struct net_bridge_port *p; 335 struct sk_buff *skb = *pskb; 336 const unsigned char *dest = eth_hdr(skb)->h_dest; 337 338 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 339 return RX_HANDLER_PASS; 340 341 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) { 342 reason = SKB_DROP_REASON_MAC_INVALID_SOURCE; 343 goto drop; 344 } 345 346 skb = skb_share_check(skb, GFP_ATOMIC); 347 if (!skb) 348 return RX_HANDLER_CONSUMED; 349 350 memset(skb->cb, 0, sizeof(struct br_input_skb_cb)); 351 br_tc_skb_miss_set(skb, false); 352 353 p = br_port_get_rcu(skb->dev); 354 if (p->flags & BR_VLAN_TUNNEL) 355 br_handle_ingress_vlan_tunnel(skb, p, nbp_vlan_group_rcu(p)); 356 357 if (unlikely(is_link_local_ether_addr(dest))) { 358 u16 fwd_mask = p->br->group_fwd_mask_required; 359 360 /* 361 * See IEEE 802.1D Table 7-10 Reserved addresses 362 * 363 * Assignment Value 364 * Bridge Group Address 01-80-C2-00-00-00 365 * (MAC Control) 802.3 01-80-C2-00-00-01 366 * (Link Aggregation) 802.3 01-80-C2-00-00-02 367 * 802.1X PAE address 01-80-C2-00-00-03 368 * 369 * 802.1AB LLDP 01-80-C2-00-00-0E 370 * 371 * Others reserved for future standardization 372 */ 373 fwd_mask |= p->group_fwd_mask; 374 switch (dest[5]) { 375 case 0x00: /* Bridge Group Address */ 376 /* If STP is turned off, 377 then must forward to keep loop detection */ 378 if (p->br->stp_enabled == BR_NO_STP || 379 fwd_mask & (1u << dest[5])) 380 goto forward; 381 *pskb = skb; 382 __br_handle_local_finish(skb); 383 return RX_HANDLER_PASS; 384 385 case 0x01: /* IEEE MAC (Pause) */ 386 reason = SKB_DROP_REASON_MAC_IEEE_MAC_CONTROL; 387 goto drop; 388 389 case 0x0E: /* 802.1AB LLDP */ 390 fwd_mask |= p->br->group_fwd_mask; 391 if (fwd_mask & (1u << dest[5])) 392 goto forward; 393 *pskb = skb; 394 __br_handle_local_finish(skb); 395 return RX_HANDLER_PASS; 396 397 default: 398 /* Allow selective forwarding for most other protocols */ 399 fwd_mask |= p->br->group_fwd_mask; 400 if (fwd_mask & (1u << dest[5])) 401 goto forward; 402 } 403 404 BR_INPUT_SKB_CB(skb)->promisc = false; 405 406 /* The else clause should be hit when nf_hook(): 407 * - returns < 0 (drop/error) 408 * - returns = 0 (stolen/nf_queue) 409 * Thus return 1 from the okfn() to signal the skb is ok to pass 410 */ 411 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 412 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 413 br_handle_local_finish) == 1) { 414 return RX_HANDLER_PASS; 415 } else { 416 return RX_HANDLER_CONSUMED; 417 } 418 } 419 420 if (unlikely(br_process_frame_type(p, skb))) 421 return RX_HANDLER_PASS; 422 423 forward: 424 if (br_mst_is_enabled(p->br)) 425 goto defer_stp_filtering; 426 427 switch (p->state) { 428 case BR_STATE_FORWARDING: 429 case BR_STATE_LEARNING: 430 defer_stp_filtering: 431 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 432 skb->pkt_type = PACKET_HOST; 433 434 return nf_hook_bridge_pre(skb, pskb); 435 default: 436 reason = SKB_DROP_REASON_BRIDGE_INGRESS_STP_STATE; 437 drop: 438 kfree_skb_reason(skb, reason); 439 } 440 return RX_HANDLER_CONSUMED; 441 } 442 443 /* This function has no purpose other than to appease the br_port_get_rcu/rtnl 444 * helpers which identify bridged ports according to the rx_handler installed 445 * on them (so there _needs_ to be a bridge rx_handler even if we don't need it 446 * to do anything useful). This bridge won't support traffic to/from the stack, 447 * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal 448 * frames from the ETH_P_XDSA packet_type handler. 449 */ 450 static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb) 451 { 452 return RX_HANDLER_PASS; 453 } 454 455 rx_handler_func_t *br_get_rx_handler(const struct net_device *dev) 456 { 457 if (netdev_uses_dsa(dev)) 458 return br_handle_frame_dummy; 459 460 return br_handle_frame; 461 } 462 463 void br_add_frame(struct net_bridge *br, struct br_frame_type *ft) 464 { 465 hlist_add_head_rcu(&ft->list, &br->frame_type_list); 466 } 467 468 void br_del_frame(struct net_bridge *br, struct br_frame_type *ft) 469 { 470 struct br_frame_type *tmp; 471 472 hlist_for_each_entry(tmp, &br->frame_type_list, list) 473 if (ft == tmp) { 474 hlist_del_rcu(&ft->list); 475 return; 476 } 477 } 478