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 26static int 27br_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 33static 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 47 /* Reset the offload_fwd_mark because there could be a stacked 48 * bridge above, and it should not think this bridge it doing 49 * that bridge's work forwarding out its ports. 50 */ 51 br_switchdev_frame_unmark(skb); 52 53 /* Bridge is just like any other port. Make sure the 54 * packet is allowed except in promisc modue when someone 55 * may be running packet capture. 56 */ 57 if (!(brdev->flags & IFF_PROMISC) && 58 !br_allowed_egress(vg, skb)) { 59 kfree_skb(skb); 60 return NET_RX_DROP; 61 } 62 63 indev = skb->dev; 64 skb->dev = brdev; 65 skb = br_handle_vlan(br, NULL, vg, skb); 66 if (!skb) 67 return NET_RX_DROP; 68 /* update the multicast stats if the packet is IGMP/MLD */ 69 br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb), 70 BR_MCAST_DIR_TX); 71 72 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 73 dev_net(indev), NULL, skb, indev, NULL, 74 br_netif_receive_skb); 75} 76 77/* note: already called with rcu_read_lock */ 78int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 79{ 80 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 81 enum br_pkt_type pkt_type = BR_PKT_UNICAST; 82 struct net_bridge_fdb_entry *dst = NULL; 83 struct net_bridge_mdb_entry *mdst; 84 bool local_rcv, mcast_hit = false; 85 struct net_bridge *br; 86 u16 vid = 0; 87 u8 state; 88 89 if (!p || p->state == BR_STATE_DISABLED) 90 goto drop; 91 92 state = p->state; 93 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid, 94 &state)) 95 goto out; 96 97 nbp_switchdev_frame_mark(p, skb); 98 99 /* insert into forwarding database after filtering to avoid spoofing */ 100 br = p->br; 101 if (p->flags & BR_LEARNING) 102 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0); 103 104 local_rcv = !!(br->dev->flags & IFF_PROMISC); 105 if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) { 106 /* by definition the broadcast is also a multicast address */ 107 if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) { 108 pkt_type = BR_PKT_BROADCAST; 109 local_rcv = true; 110 } else { 111 pkt_type = BR_PKT_MULTICAST; 112 if (br_multicast_rcv(br, p, skb, vid)) 113 goto drop; 114 } 115 } 116 117 if (state == BR_STATE_LEARNING) 118 goto drop; 119 120 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 121 BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED); 122 123 if (IS_ENABLED(CONFIG_INET) && 124 (skb->protocol == htons(ETH_P_ARP) || 125 skb->protocol == htons(ETH_P_RARP))) { 126 br_do_proxy_suppress_arp(skb, br, vid, p); 127 } else if (IS_ENABLED(CONFIG_IPV6) && 128 skb->protocol == htons(ETH_P_IPV6) && 129 br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) && 130 pskb_may_pull(skb, sizeof(struct ipv6hdr) + 131 sizeof(struct nd_msg)) && 132 ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) { 133 struct nd_msg *msg, _msg; 134 135 msg = br_is_nd_neigh_msg(skb, &_msg); 136 if (msg) 137 br_do_suppress_nd(skb, br, vid, p, msg); 138 } 139 140 switch (pkt_type) { 141 case BR_PKT_MULTICAST: 142 mdst = br_mdb_get(br, skb, vid); 143 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 144 br_multicast_querier_exists(br, eth_hdr(skb))) { 145 if ((mdst && mdst->host_joined) || 146 br_multicast_is_router(br)) { 147 local_rcv = true; 148 DEV_STATS_INC(br->dev, multicast); 149 } 150 mcast_hit = true; 151 } else { 152 local_rcv = true; 153 DEV_STATS_INC(br->dev, multicast); 154 } 155 break; 156 case BR_PKT_UNICAST: 157 dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid); 158 default: 159 break; 160 } 161 162 if (dst) { 163 unsigned long now = jiffies; 164 165 if (test_bit(BR_FDB_LOCAL, &dst->flags)) 166 return br_pass_frame_up(skb); 167 168 if (now != dst->used) 169 dst->used = now; 170 br_forward(dst->dst, skb, local_rcv, false); 171 } else { 172 if (!mcast_hit) 173 br_flood(br, skb, pkt_type, local_rcv, false); 174 else 175 br_multicast_flood(mdst, skb, local_rcv, false); 176 } 177 178 if (local_rcv) 179 return br_pass_frame_up(skb); 180 181out: 182 return 0; 183drop: 184 kfree_skb(skb); 185 goto out; 186} 187EXPORT_SYMBOL_GPL(br_handle_frame_finish); 188 189static void __br_handle_local_finish(struct sk_buff *skb) 190{ 191 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 192 u16 vid = 0; 193 194 /* check if vlan is allowed, to avoid spoofing */ 195 if ((p->flags & BR_LEARNING) && 196 nbp_state_should_learn(p) && 197 !br_opt_get(p->br, BROPT_NO_LL_LEARN) && 198 br_should_learn(p, skb, &vid)) 199 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0); 200} 201 202/* note: already called with rcu_read_lock */ 203static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 204{ 205 __br_handle_local_finish(skb); 206 207 /* return 1 to signal the okfn() was called so it's ok to use the skb */ 208 return 1; 209} 210 211static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb) 212{ 213#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE 214 struct nf_hook_entries *e = NULL; 215 struct nf_hook_state state; 216 unsigned int verdict, i; 217 struct net *net; 218 int ret; 219 220 net = dev_net(skb->dev); 221#ifdef HAVE_JUMP_LABEL 222 if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING])) 223 goto frame_finish; 224#endif 225 226 e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]); 227 if (!e) 228 goto frame_finish; 229 230 nf_hook_state_init(&state, NF_BR_PRE_ROUTING, 231 NFPROTO_BRIDGE, skb->dev, NULL, NULL, 232 net, br_handle_frame_finish); 233 234 for (i = 0; i < e->num_hook_entries; i++) { 235 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state); 236 switch (verdict & NF_VERDICT_MASK) { 237 case NF_ACCEPT: 238 if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) { 239 *pskb = skb; 240 return RX_HANDLER_PASS; 241 } 242 break; 243 case NF_DROP: 244 kfree_skb(skb); 245 return RX_HANDLER_CONSUMED; 246 case NF_QUEUE: 247 ret = nf_queue(skb, &state, i, verdict); 248 if (ret == 1) 249 continue; 250 return RX_HANDLER_CONSUMED; 251 default: /* STOLEN */ 252 return RX_HANDLER_CONSUMED; 253 } 254 } 255frame_finish: 256 net = dev_net(skb->dev); 257 br_handle_frame_finish(net, NULL, skb); 258#else 259 br_handle_frame_finish(dev_net(skb->dev), NULL, skb); 260#endif 261 return RX_HANDLER_CONSUMED; 262} 263 264/* 265 * Return NULL if skb is handled 266 * note: already called with rcu_read_lock 267 */ 268static rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 269{ 270 struct net_bridge_port *p; 271 struct sk_buff *skb = *pskb; 272 const unsigned char *dest = eth_hdr(skb)->h_dest; 273 274 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 275 return RX_HANDLER_PASS; 276 277 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 278 goto drop; 279 280 skb = skb_share_check(skb, GFP_ATOMIC); 281 if (!skb) 282 return RX_HANDLER_CONSUMED; 283 284 memset(skb->cb, 0, sizeof(struct br_input_skb_cb)); 285 286 p = br_port_get_rcu(skb->dev); 287 if (p->flags & BR_VLAN_TUNNEL) { 288 if (br_handle_ingress_vlan_tunnel(skb, p, 289 nbp_vlan_group_rcu(p))) 290 goto drop; 291 } 292 293 if (unlikely(is_link_local_ether_addr(dest))) { 294 u16 fwd_mask = p->br->group_fwd_mask_required; 295 296 /* 297 * See IEEE 802.1D Table 7-10 Reserved addresses 298 * 299 * Assignment Value 300 * Bridge Group Address 01-80-C2-00-00-00 301 * (MAC Control) 802.3 01-80-C2-00-00-01 302 * (Link Aggregation) 802.3 01-80-C2-00-00-02 303 * 802.1X PAE address 01-80-C2-00-00-03 304 * 305 * 802.1AB LLDP 01-80-C2-00-00-0E 306 * 307 * Others reserved for future standardization 308 */ 309 fwd_mask |= p->group_fwd_mask; 310 switch (dest[5]) { 311 case 0x00: /* Bridge Group Address */ 312 /* If STP is turned off, 313 then must forward to keep loop detection */ 314 if (p->br->stp_enabled == BR_NO_STP || 315 fwd_mask & (1u << dest[5])) 316 goto forward; 317 *pskb = skb; 318 __br_handle_local_finish(skb); 319 return RX_HANDLER_PASS; 320 321 case 0x01: /* IEEE MAC (Pause) */ 322 goto drop; 323 324 case 0x0E: /* 802.1AB LLDP */ 325 fwd_mask |= p->br->group_fwd_mask; 326 if (fwd_mask & (1u << dest[5])) 327 goto forward; 328 *pskb = skb; 329 __br_handle_local_finish(skb); 330 return RX_HANDLER_PASS; 331 332 default: 333 /* Allow selective forwarding for most other protocols */ 334 fwd_mask |= p->br->group_fwd_mask; 335 if (fwd_mask & (1u << dest[5])) 336 goto forward; 337 } 338 339 /* The else clause should be hit when nf_hook(): 340 * - returns < 0 (drop/error) 341 * - returns = 0 (stolen/nf_queue) 342 * Thus return 1 from the okfn() to signal the skb is ok to pass 343 */ 344 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 345 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 346 br_handle_local_finish) == 1) { 347 return RX_HANDLER_PASS; 348 } else { 349 return RX_HANDLER_CONSUMED; 350 } 351 } 352 353 if (unlikely(br_mrp_process(p, skb))) 354 return RX_HANDLER_PASS; 355 356forward: 357 switch (p->state) { 358 case BR_STATE_FORWARDING: 359 case BR_STATE_LEARNING: 360 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 361 skb->pkt_type = PACKET_HOST; 362 363 return nf_hook_bridge_pre(skb, pskb); 364 default: 365drop: 366 kfree_skb(skb); 367 } 368 return RX_HANDLER_CONSUMED; 369} 370 371/* This function has no purpose other than to appease the br_port_get_rcu/rtnl 372 * helpers which identify bridged ports according to the rx_handler installed 373 * on them (so there _needs_ to be a bridge rx_handler even if we don't need it 374 * to do anything useful). This bridge won't support traffic to/from the stack, 375 * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal 376 * frames from the ETH_P_XDSA packet_type handler. 377 */ 378static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb) 379{ 380 return RX_HANDLER_PASS; 381} 382 383rx_handler_func_t *br_get_rx_handler(const struct net_device *dev) 384{ 385 if (netdev_uses_dsa(dev)) 386 return br_handle_frame_dummy; 387 388 return br_handle_frame; 389} 390