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