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