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 || READ_ONCE(fdb_src->dst) != p || 113 test_bit(BR_FDB_LOCAL, &fdb_src->flags)) 114 goto drop; 115 } 116 117 nbp_switchdev_frame_mark(p, skb); 118 119 /* insert into forwarding database after filtering to avoid spoofing */ 120 if (p->flags & BR_LEARNING) 121 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0); 122 123 local_rcv = !!(br->dev->flags & IFF_PROMISC); 124 if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) { 125 /* by definition the broadcast is also a multicast address */ 126 if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) { 127 pkt_type = BR_PKT_BROADCAST; 128 local_rcv = true; 129 } else { 130 pkt_type = BR_PKT_MULTICAST; 131 if (br_multicast_rcv(&brmctx, &pmctx, vlan, skb, vid)) 132 goto drop; 133 } 134 } 135 136 if (state == BR_STATE_LEARNING) 137 goto drop; 138 139 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 140 BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED); 141 142 if (IS_ENABLED(CONFIG_INET) && 143 (skb->protocol == htons(ETH_P_ARP) || 144 skb->protocol == htons(ETH_P_RARP))) { 145 br_do_proxy_suppress_arp(skb, br, vid, p); 146 } else if (IS_ENABLED(CONFIG_IPV6) && 147 skb->protocol == htons(ETH_P_IPV6) && 148 br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) && 149 pskb_may_pull(skb, sizeof(struct ipv6hdr) + 150 sizeof(struct nd_msg)) && 151 ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) { 152 struct nd_msg *msg, _msg; 153 154 msg = br_is_nd_neigh_msg(skb, &_msg); 155 if (msg) 156 br_do_suppress_nd(skb, br, vid, p, msg); 157 } 158 159 switch (pkt_type) { 160 case BR_PKT_MULTICAST: 161 mdst = br_mdb_get(brmctx, skb, vid); 162 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 163 br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) { 164 if ((mdst && mdst->host_joined) || 165 br_multicast_is_router(brmctx, skb)) { 166 local_rcv = true; 167 br->dev->stats.multicast++; 168 } 169 mcast_hit = true; 170 } else { 171 local_rcv = true; 172 br->dev->stats.multicast++; 173 } 174 break; 175 case BR_PKT_UNICAST: 176 dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid); 177 break; 178 default: 179 break; 180 } 181 182 if (dst) { 183 unsigned long now = jiffies; 184 185 if (test_bit(BR_FDB_LOCAL, &dst->flags)) 186 return br_pass_frame_up(skb); 187 188 if (now != dst->used) 189 dst->used = now; 190 br_forward(dst->dst, skb, local_rcv, false); 191 } else { 192 if (!mcast_hit) 193 br_flood(br, skb, pkt_type, local_rcv, false); 194 else 195 br_multicast_flood(mdst, skb, brmctx, local_rcv, false); 196 } 197 198 if (local_rcv) 199 return br_pass_frame_up(skb); 200 201 out: 202 return 0; 203 drop: 204 kfree_skb(skb); 205 goto out; 206 } 207 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 208 209 static void __br_handle_local_finish(struct sk_buff *skb) 210 { 211 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 212 u16 vid = 0; 213 214 /* check if vlan is allowed, to avoid spoofing */ 215 if ((p->flags & BR_LEARNING) && 216 nbp_state_should_learn(p) && 217 !br_opt_get(p->br, BROPT_NO_LL_LEARN) && 218 br_should_learn(p, skb, &vid)) 219 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0); 220 } 221 222 /* note: already called with rcu_read_lock */ 223 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 224 { 225 __br_handle_local_finish(skb); 226 227 /* return 1 to signal the okfn() was called so it's ok to use the skb */ 228 return 1; 229 } 230 231 static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb) 232 { 233 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE 234 struct nf_hook_entries *e = NULL; 235 struct nf_hook_state state; 236 unsigned int verdict, i; 237 struct net *net; 238 int ret; 239 240 net = dev_net(skb->dev); 241 #ifdef HAVE_JUMP_LABEL 242 if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING])) 243 goto frame_finish; 244 #endif 245 246 e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]); 247 if (!e) 248 goto frame_finish; 249 250 nf_hook_state_init(&state, NF_BR_PRE_ROUTING, 251 NFPROTO_BRIDGE, skb->dev, NULL, NULL, 252 net, br_handle_frame_finish); 253 254 for (i = 0; i < e->num_hook_entries; i++) { 255 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state); 256 switch (verdict & NF_VERDICT_MASK) { 257 case NF_ACCEPT: 258 if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) { 259 *pskb = skb; 260 return RX_HANDLER_PASS; 261 } 262 break; 263 case NF_DROP: 264 kfree_skb(skb); 265 return RX_HANDLER_CONSUMED; 266 case NF_QUEUE: 267 ret = nf_queue(skb, &state, i, verdict); 268 if (ret == 1) 269 continue; 270 return RX_HANDLER_CONSUMED; 271 default: /* STOLEN */ 272 return RX_HANDLER_CONSUMED; 273 } 274 } 275 frame_finish: 276 net = dev_net(skb->dev); 277 br_handle_frame_finish(net, NULL, skb); 278 #else 279 br_handle_frame_finish(dev_net(skb->dev), NULL, skb); 280 #endif 281 return RX_HANDLER_CONSUMED; 282 } 283 284 /* Return 0 if the frame was not processed otherwise 1 285 * note: already called with rcu_read_lock 286 */ 287 static int br_process_frame_type(struct net_bridge_port *p, 288 struct sk_buff *skb) 289 { 290 struct br_frame_type *tmp; 291 292 hlist_for_each_entry_rcu(tmp, &p->br->frame_type_list, list) 293 if (unlikely(tmp->type == skb->protocol)) 294 return tmp->frame_handler(p, skb); 295 296 return 0; 297 } 298 299 /* 300 * Return NULL if skb is handled 301 * note: already called with rcu_read_lock 302 */ 303 static rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 304 { 305 struct net_bridge_port *p; 306 struct sk_buff *skb = *pskb; 307 const unsigned char *dest = eth_hdr(skb)->h_dest; 308 309 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 310 return RX_HANDLER_PASS; 311 312 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 313 goto drop; 314 315 skb = skb_share_check(skb, GFP_ATOMIC); 316 if (!skb) 317 return RX_HANDLER_CONSUMED; 318 319 memset(skb->cb, 0, sizeof(struct br_input_skb_cb)); 320 321 p = br_port_get_rcu(skb->dev); 322 if (p->flags & BR_VLAN_TUNNEL) 323 br_handle_ingress_vlan_tunnel(skb, p, nbp_vlan_group_rcu(p)); 324 325 if (unlikely(is_link_local_ether_addr(dest))) { 326 u16 fwd_mask = p->br->group_fwd_mask_required; 327 328 /* 329 * See IEEE 802.1D Table 7-10 Reserved addresses 330 * 331 * Assignment Value 332 * Bridge Group Address 01-80-C2-00-00-00 333 * (MAC Control) 802.3 01-80-C2-00-00-01 334 * (Link Aggregation) 802.3 01-80-C2-00-00-02 335 * 802.1X PAE address 01-80-C2-00-00-03 336 * 337 * 802.1AB LLDP 01-80-C2-00-00-0E 338 * 339 * Others reserved for future standardization 340 */ 341 fwd_mask |= p->group_fwd_mask; 342 switch (dest[5]) { 343 case 0x00: /* Bridge Group Address */ 344 /* If STP is turned off, 345 then must forward to keep loop detection */ 346 if (p->br->stp_enabled == BR_NO_STP || 347 fwd_mask & (1u << dest[5])) 348 goto forward; 349 *pskb = skb; 350 __br_handle_local_finish(skb); 351 return RX_HANDLER_PASS; 352 353 case 0x01: /* IEEE MAC (Pause) */ 354 goto drop; 355 356 case 0x0E: /* 802.1AB LLDP */ 357 fwd_mask |= p->br->group_fwd_mask; 358 if (fwd_mask & (1u << dest[5])) 359 goto forward; 360 *pskb = skb; 361 __br_handle_local_finish(skb); 362 return RX_HANDLER_PASS; 363 364 default: 365 /* Allow selective forwarding for most other protocols */ 366 fwd_mask |= p->br->group_fwd_mask; 367 if (fwd_mask & (1u << dest[5])) 368 goto forward; 369 } 370 371 /* The else clause should be hit when nf_hook(): 372 * - returns < 0 (drop/error) 373 * - returns = 0 (stolen/nf_queue) 374 * Thus return 1 from the okfn() to signal the skb is ok to pass 375 */ 376 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 377 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 378 br_handle_local_finish) == 1) { 379 return RX_HANDLER_PASS; 380 } else { 381 return RX_HANDLER_CONSUMED; 382 } 383 } 384 385 if (unlikely(br_process_frame_type(p, skb))) 386 return RX_HANDLER_PASS; 387 388 forward: 389 if (br_mst_is_enabled(p->br)) 390 goto defer_stp_filtering; 391 392 switch (p->state) { 393 case BR_STATE_FORWARDING: 394 case BR_STATE_LEARNING: 395 defer_stp_filtering: 396 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 397 skb->pkt_type = PACKET_HOST; 398 399 return nf_hook_bridge_pre(skb, pskb); 400 default: 401 drop: 402 kfree_skb(skb); 403 } 404 return RX_HANDLER_CONSUMED; 405 } 406 407 /* This function has no purpose other than to appease the br_port_get_rcu/rtnl 408 * helpers which identify bridged ports according to the rx_handler installed 409 * on them (so there _needs_ to be a bridge rx_handler even if we don't need it 410 * to do anything useful). This bridge won't support traffic to/from the stack, 411 * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal 412 * frames from the ETH_P_XDSA packet_type handler. 413 */ 414 static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb) 415 { 416 return RX_HANDLER_PASS; 417 } 418 419 rx_handler_func_t *br_get_rx_handler(const struct net_device *dev) 420 { 421 if (netdev_uses_dsa(dev)) 422 return br_handle_frame_dummy; 423 424 return br_handle_frame; 425 } 426 427 void br_add_frame(struct net_bridge *br, struct br_frame_type *ft) 428 { 429 hlist_add_head_rcu(&ft->list, &br->frame_type_list); 430 } 431 432 void br_del_frame(struct net_bridge *br, struct br_frame_type *ft) 433 { 434 struct br_frame_type *tmp; 435 436 hlist_for_each_entry(tmp, &br->frame_type_list, list) 437 if (ft == tmp) { 438 hlist_del_rcu(&ft->list); 439 return; 440 } 441 } 442