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