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 struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats); 39 40 u64_stats_update_begin(&brstats->syncp); 41 brstats->rx_packets++; 42 brstats->rx_bytes += skb->len; 43 u64_stats_update_end(&brstats->syncp); 44 45 vg = br_vlan_group_rcu(br); 46 /* Bridge is just like any other port. Make sure the 47 * packet is allowed except in promisc modue when someone 48 * may be running packet capture. 49 */ 50 if (!(brdev->flags & IFF_PROMISC) && 51 !br_allowed_egress(vg, skb)) { 52 kfree_skb(skb); 53 return NET_RX_DROP; 54 } 55 56 indev = skb->dev; 57 skb->dev = brdev; 58 skb = br_handle_vlan(br, NULL, vg, skb); 59 if (!skb) 60 return NET_RX_DROP; 61 /* update the multicast stats if the packet is IGMP/MLD */ 62 br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb), 63 BR_MCAST_DIR_TX); 64 65 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 66 dev_net(indev), NULL, skb, indev, NULL, 67 br_netif_receive_skb); 68 } 69 70 /* note: already called with rcu_read_lock */ 71 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 72 { 73 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 74 enum br_pkt_type pkt_type = BR_PKT_UNICAST; 75 struct net_bridge_fdb_entry *dst = NULL; 76 struct net_bridge_mdb_entry *mdst; 77 bool local_rcv, mcast_hit = false; 78 struct net_bridge *br; 79 u16 vid = 0; 80 u8 state; 81 82 if (!p || p->state == BR_STATE_DISABLED) 83 goto drop; 84 85 state = p->state; 86 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid, 87 &state)) 88 goto out; 89 90 nbp_switchdev_frame_mark(p, skb); 91 92 /* insert into forwarding database after filtering to avoid spoofing */ 93 br = p->br; 94 if (p->flags & BR_LEARNING) 95 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0); 96 97 local_rcv = !!(br->dev->flags & IFF_PROMISC); 98 if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) { 99 /* by definition the broadcast is also a multicast address */ 100 if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) { 101 pkt_type = BR_PKT_BROADCAST; 102 local_rcv = true; 103 } else { 104 pkt_type = BR_PKT_MULTICAST; 105 if (br_multicast_rcv(br, p, skb, vid)) 106 goto drop; 107 } 108 } 109 110 if (state == BR_STATE_LEARNING) 111 goto drop; 112 113 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 114 BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED); 115 116 if (IS_ENABLED(CONFIG_INET) && 117 (skb->protocol == htons(ETH_P_ARP) || 118 skb->protocol == htons(ETH_P_RARP))) { 119 br_do_proxy_suppress_arp(skb, br, vid, p); 120 } else if (IS_ENABLED(CONFIG_IPV6) && 121 skb->protocol == htons(ETH_P_IPV6) && 122 br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) && 123 pskb_may_pull(skb, sizeof(struct ipv6hdr) + 124 sizeof(struct nd_msg)) && 125 ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) { 126 struct nd_msg *msg, _msg; 127 128 msg = br_is_nd_neigh_msg(skb, &_msg); 129 if (msg) 130 br_do_suppress_nd(skb, br, vid, p, msg); 131 } 132 133 switch (pkt_type) { 134 case BR_PKT_MULTICAST: 135 mdst = br_mdb_get(br, skb, vid); 136 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 137 br_multicast_querier_exists(br, eth_hdr(skb), mdst)) { 138 if ((mdst && mdst->host_joined) || 139 br_multicast_is_router(br)) { 140 local_rcv = true; 141 br->dev->stats.multicast++; 142 } 143 mcast_hit = true; 144 } else { 145 local_rcv = true; 146 br->dev->stats.multicast++; 147 } 148 break; 149 case BR_PKT_UNICAST: 150 dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid); 151 default: 152 break; 153 } 154 155 if (dst) { 156 unsigned long now = jiffies; 157 158 if (test_bit(BR_FDB_LOCAL, &dst->flags)) 159 return br_pass_frame_up(skb); 160 161 if (now != dst->used) 162 dst->used = now; 163 br_forward(dst->dst, skb, local_rcv, false); 164 } else { 165 if (!mcast_hit) 166 br_flood(br, skb, pkt_type, local_rcv, false); 167 else 168 br_multicast_flood(mdst, skb, local_rcv, false); 169 } 170 171 if (local_rcv) 172 return br_pass_frame_up(skb); 173 174 out: 175 return 0; 176 drop: 177 kfree_skb(skb); 178 goto out; 179 } 180 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 181 182 static void __br_handle_local_finish(struct sk_buff *skb) 183 { 184 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 185 u16 vid = 0; 186 187 /* check if vlan is allowed, to avoid spoofing */ 188 if ((p->flags & BR_LEARNING) && 189 nbp_state_should_learn(p) && 190 !br_opt_get(p->br, BROPT_NO_LL_LEARN) && 191 br_should_learn(p, skb, &vid)) 192 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0); 193 } 194 195 /* note: already called with rcu_read_lock */ 196 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 197 { 198 __br_handle_local_finish(skb); 199 200 /* return 1 to signal the okfn() was called so it's ok to use the skb */ 201 return 1; 202 } 203 204 static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb) 205 { 206 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE 207 struct nf_hook_entries *e = NULL; 208 struct nf_hook_state state; 209 unsigned int verdict, i; 210 struct net *net; 211 int ret; 212 213 net = dev_net(skb->dev); 214 #ifdef HAVE_JUMP_LABEL 215 if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING])) 216 goto frame_finish; 217 #endif 218 219 e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]); 220 if (!e) 221 goto frame_finish; 222 223 nf_hook_state_init(&state, NF_BR_PRE_ROUTING, 224 NFPROTO_BRIDGE, skb->dev, NULL, NULL, 225 net, br_handle_frame_finish); 226 227 for (i = 0; i < e->num_hook_entries; i++) { 228 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state); 229 switch (verdict & NF_VERDICT_MASK) { 230 case NF_ACCEPT: 231 if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) { 232 *pskb = skb; 233 return RX_HANDLER_PASS; 234 } 235 break; 236 case NF_DROP: 237 kfree_skb(skb); 238 return RX_HANDLER_CONSUMED; 239 case NF_QUEUE: 240 ret = nf_queue(skb, &state, i, verdict); 241 if (ret == 1) 242 continue; 243 return RX_HANDLER_CONSUMED; 244 default: /* STOLEN */ 245 return RX_HANDLER_CONSUMED; 246 } 247 } 248 frame_finish: 249 net = dev_net(skb->dev); 250 br_handle_frame_finish(net, NULL, skb); 251 #else 252 br_handle_frame_finish(dev_net(skb->dev), NULL, skb); 253 #endif 254 return RX_HANDLER_CONSUMED; 255 } 256 257 /* Return 0 if the frame was not processed otherwise 1 258 * note: already called with rcu_read_lock 259 */ 260 static int br_process_frame_type(struct net_bridge_port *p, 261 struct sk_buff *skb) 262 { 263 struct br_frame_type *tmp; 264 265 hlist_for_each_entry_rcu(tmp, &p->br->frame_type_list, list) 266 if (unlikely(tmp->type == skb->protocol)) 267 return tmp->frame_handler(p, skb); 268 269 return 0; 270 } 271 272 /* 273 * Return NULL if skb is handled 274 * note: already called with rcu_read_lock 275 */ 276 static rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 277 { 278 struct net_bridge_port *p; 279 struct sk_buff *skb = *pskb; 280 const unsigned char *dest = eth_hdr(skb)->h_dest; 281 282 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 283 return RX_HANDLER_PASS; 284 285 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 286 goto drop; 287 288 skb = skb_share_check(skb, GFP_ATOMIC); 289 if (!skb) 290 return RX_HANDLER_CONSUMED; 291 292 memset(skb->cb, 0, sizeof(struct br_input_skb_cb)); 293 294 p = br_port_get_rcu(skb->dev); 295 if (p->flags & BR_VLAN_TUNNEL) { 296 if (br_handle_ingress_vlan_tunnel(skb, p, 297 nbp_vlan_group_rcu(p))) 298 goto drop; 299 } 300 301 if (unlikely(is_link_local_ether_addr(dest))) { 302 u16 fwd_mask = p->br->group_fwd_mask_required; 303 304 /* 305 * See IEEE 802.1D Table 7-10 Reserved addresses 306 * 307 * Assignment Value 308 * Bridge Group Address 01-80-C2-00-00-00 309 * (MAC Control) 802.3 01-80-C2-00-00-01 310 * (Link Aggregation) 802.3 01-80-C2-00-00-02 311 * 802.1X PAE address 01-80-C2-00-00-03 312 * 313 * 802.1AB LLDP 01-80-C2-00-00-0E 314 * 315 * Others reserved for future standardization 316 */ 317 fwd_mask |= p->group_fwd_mask; 318 switch (dest[5]) { 319 case 0x00: /* Bridge Group Address */ 320 /* If STP is turned off, 321 then must forward to keep loop detection */ 322 if (p->br->stp_enabled == BR_NO_STP || 323 fwd_mask & (1u << dest[5])) 324 goto forward; 325 *pskb = skb; 326 __br_handle_local_finish(skb); 327 return RX_HANDLER_PASS; 328 329 case 0x01: /* IEEE MAC (Pause) */ 330 goto drop; 331 332 case 0x0E: /* 802.1AB LLDP */ 333 fwd_mask |= p->br->group_fwd_mask; 334 if (fwd_mask & (1u << dest[5])) 335 goto forward; 336 *pskb = skb; 337 __br_handle_local_finish(skb); 338 return RX_HANDLER_PASS; 339 340 default: 341 /* Allow selective forwarding for most other protocols */ 342 fwd_mask |= p->br->group_fwd_mask; 343 if (fwd_mask & (1u << dest[5])) 344 goto forward; 345 } 346 347 /* The else clause should be hit when nf_hook(): 348 * - returns < 0 (drop/error) 349 * - returns = 0 (stolen/nf_queue) 350 * Thus return 1 from the okfn() to signal the skb is ok to pass 351 */ 352 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 353 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 354 br_handle_local_finish) == 1) { 355 return RX_HANDLER_PASS; 356 } else { 357 return RX_HANDLER_CONSUMED; 358 } 359 } 360 361 if (unlikely(br_process_frame_type(p, skb))) 362 return RX_HANDLER_PASS; 363 364 forward: 365 switch (p->state) { 366 case BR_STATE_FORWARDING: 367 case BR_STATE_LEARNING: 368 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 369 skb->pkt_type = PACKET_HOST; 370 371 return nf_hook_bridge_pre(skb, pskb); 372 default: 373 drop: 374 kfree_skb(skb); 375 } 376 return RX_HANDLER_CONSUMED; 377 } 378 379 /* This function has no purpose other than to appease the br_port_get_rcu/rtnl 380 * helpers which identify bridged ports according to the rx_handler installed 381 * on them (so there _needs_ to be a bridge rx_handler even if we don't need it 382 * to do anything useful). This bridge won't support traffic to/from the stack, 383 * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal 384 * frames from the ETH_P_XDSA packet_type handler. 385 */ 386 static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb) 387 { 388 return RX_HANDLER_PASS; 389 } 390 391 rx_handler_func_t *br_get_rx_handler(const struct net_device *dev) 392 { 393 if (netdev_uses_dsa(dev)) 394 return br_handle_frame_dummy; 395 396 return br_handle_frame; 397 } 398 399 void br_add_frame(struct net_bridge *br, struct br_frame_type *ft) 400 { 401 hlist_add_head_rcu(&ft->list, &br->frame_type_list); 402 } 403 404 void br_del_frame(struct net_bridge *br, struct br_frame_type *ft) 405 { 406 struct br_frame_type *tmp; 407 408 hlist_for_each_entry(tmp, &br->frame_type_list, list) 409 if (ft == tmp) { 410 hlist_del_rcu(&ft->list); 411 return; 412 } 413 } 414