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 br_tc_skb_miss_set(skb, false); 338 339 p = br_port_get_rcu(skb->dev); 340 if (p->flags & BR_VLAN_TUNNEL) 341 br_handle_ingress_vlan_tunnel(skb, p, nbp_vlan_group_rcu(p)); 342 343 if (unlikely(is_link_local_ether_addr(dest))) { 344 u16 fwd_mask = p->br->group_fwd_mask_required; 345 346 /* 347 * See IEEE 802.1D Table 7-10 Reserved addresses 348 * 349 * Assignment Value 350 * Bridge Group Address 01-80-C2-00-00-00 351 * (MAC Control) 802.3 01-80-C2-00-00-01 352 * (Link Aggregation) 802.3 01-80-C2-00-00-02 353 * 802.1X PAE address 01-80-C2-00-00-03 354 * 355 * 802.1AB LLDP 01-80-C2-00-00-0E 356 * 357 * Others reserved for future standardization 358 */ 359 fwd_mask |= p->group_fwd_mask; 360 switch (dest[5]) { 361 case 0x00: /* Bridge Group Address */ 362 /* If STP is turned off, 363 then must forward to keep loop detection */ 364 if (p->br->stp_enabled == BR_NO_STP || 365 fwd_mask & (1u << dest[5])) 366 goto forward; 367 *pskb = skb; 368 __br_handle_local_finish(skb); 369 return RX_HANDLER_PASS; 370 371 case 0x01: /* IEEE MAC (Pause) */ 372 goto drop; 373 374 case 0x0E: /* 802.1AB LLDP */ 375 fwd_mask |= p->br->group_fwd_mask; 376 if (fwd_mask & (1u << dest[5])) 377 goto forward; 378 *pskb = skb; 379 __br_handle_local_finish(skb); 380 return RX_HANDLER_PASS; 381 382 default: 383 /* Allow selective forwarding for most other protocols */ 384 fwd_mask |= p->br->group_fwd_mask; 385 if (fwd_mask & (1u << dest[5])) 386 goto forward; 387 } 388 389 /* The else clause should be hit when nf_hook(): 390 * - returns < 0 (drop/error) 391 * - returns = 0 (stolen/nf_queue) 392 * Thus return 1 from the okfn() to signal the skb is ok to pass 393 */ 394 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 395 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 396 br_handle_local_finish) == 1) { 397 return RX_HANDLER_PASS; 398 } else { 399 return RX_HANDLER_CONSUMED; 400 } 401 } 402 403 if (unlikely(br_process_frame_type(p, skb))) 404 return RX_HANDLER_PASS; 405 406 forward: 407 if (br_mst_is_enabled(p->br)) 408 goto defer_stp_filtering; 409 410 switch (p->state) { 411 case BR_STATE_FORWARDING: 412 case BR_STATE_LEARNING: 413 defer_stp_filtering: 414 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 415 skb->pkt_type = PACKET_HOST; 416 417 return nf_hook_bridge_pre(skb, pskb); 418 default: 419 drop: 420 kfree_skb(skb); 421 } 422 return RX_HANDLER_CONSUMED; 423 } 424 425 /* This function has no purpose other than to appease the br_port_get_rcu/rtnl 426 * helpers which identify bridged ports according to the rx_handler installed 427 * on them (so there _needs_ to be a bridge rx_handler even if we don't need it 428 * to do anything useful). This bridge won't support traffic to/from the stack, 429 * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal 430 * frames from the ETH_P_XDSA packet_type handler. 431 */ 432 static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb) 433 { 434 return RX_HANDLER_PASS; 435 } 436 437 rx_handler_func_t *br_get_rx_handler(const struct net_device *dev) 438 { 439 if (netdev_uses_dsa(dev)) 440 return br_handle_frame_dummy; 441 442 return br_handle_frame; 443 } 444 445 void br_add_frame(struct net_bridge *br, struct br_frame_type *ft) 446 { 447 hlist_add_head_rcu(&ft->list, &br->frame_type_list); 448 } 449 450 void br_del_frame(struct net_bridge *br, struct br_frame_type *ft) 451 { 452 struct br_frame_type *tmp; 453 454 hlist_for_each_entry(tmp, &br->frame_type_list, list) 455 if (ft == tmp) { 456 hlist_del_rcu(&ft->list); 457 return; 458 } 459 } 460