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 <linux/export.h> 21 #include <linux/rculist.h> 22 #include "br_private.h" 23 #include "br_private_tunnel.h" 24 25 static int 26 br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb) 27 { 28 br_drop_fake_rtable(skb); 29 return netif_receive_skb(skb); 30 } 31 32 static int br_pass_frame_up(struct sk_buff *skb) 33 { 34 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; 35 struct net_bridge *br = netdev_priv(brdev); 36 struct net_bridge_vlan_group *vg; 37 struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats); 38 39 u64_stats_update_begin(&brstats->syncp); 40 brstats->rx_packets++; 41 brstats->rx_bytes += skb->len; 42 u64_stats_update_end(&brstats->syncp); 43 44 vg = br_vlan_group_rcu(br); 45 /* Bridge is just like any other port. Make sure the 46 * packet is allowed except in promisc modue when someone 47 * may be running packet capture. 48 */ 49 if (!(brdev->flags & IFF_PROMISC) && 50 !br_allowed_egress(vg, skb)) { 51 kfree_skb(skb); 52 return NET_RX_DROP; 53 } 54 55 indev = skb->dev; 56 skb->dev = brdev; 57 skb = br_handle_vlan(br, NULL, vg, skb); 58 if (!skb) 59 return NET_RX_DROP; 60 /* update the multicast stats if the packet is IGMP/MLD */ 61 br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb), 62 BR_MCAST_DIR_TX); 63 64 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 65 dev_net(indev), NULL, skb, indev, NULL, 66 br_netif_receive_skb); 67 } 68 69 /* note: already called with rcu_read_lock */ 70 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 71 { 72 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 73 enum br_pkt_type pkt_type = BR_PKT_UNICAST; 74 struct net_bridge_fdb_entry *dst = NULL; 75 struct net_bridge_mdb_entry *mdst; 76 bool local_rcv, mcast_hit = false; 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 state = p->state; 85 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid, 86 &state)) 87 goto out; 88 89 nbp_switchdev_frame_mark(p, skb); 90 91 /* insert into forwarding database after filtering to avoid spoofing */ 92 br = p->br; 93 if (p->flags & BR_LEARNING) 94 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0); 95 96 local_rcv = !!(br->dev->flags & IFF_PROMISC); 97 if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) { 98 /* by definition the broadcast is also a multicast address */ 99 if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) { 100 pkt_type = BR_PKT_BROADCAST; 101 local_rcv = true; 102 } else { 103 pkt_type = BR_PKT_MULTICAST; 104 if (br_multicast_rcv(br, p, skb, vid)) 105 goto drop; 106 } 107 } 108 109 if (state == BR_STATE_LEARNING) 110 goto drop; 111 112 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 113 BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED); 114 115 if (IS_ENABLED(CONFIG_INET) && 116 (skb->protocol == htons(ETH_P_ARP) || 117 skb->protocol == htons(ETH_P_RARP))) { 118 br_do_proxy_suppress_arp(skb, br, vid, p); 119 } else if (IS_ENABLED(CONFIG_IPV6) && 120 skb->protocol == htons(ETH_P_IPV6) && 121 br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) && 122 pskb_may_pull(skb, sizeof(struct ipv6hdr) + 123 sizeof(struct nd_msg)) && 124 ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) { 125 struct nd_msg *msg, _msg; 126 127 msg = br_is_nd_neigh_msg(skb, &_msg); 128 if (msg) 129 br_do_suppress_nd(skb, br, vid, p, msg); 130 } 131 132 switch (pkt_type) { 133 case BR_PKT_MULTICAST: 134 mdst = br_mdb_get(br, skb, vid); 135 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 136 br_multicast_querier_exists(br, eth_hdr(skb))) { 137 if ((mdst && mdst->host_joined) || 138 br_multicast_is_router(br)) { 139 local_rcv = true; 140 br->dev->stats.multicast++; 141 } 142 mcast_hit = true; 143 } else { 144 local_rcv = true; 145 br->dev->stats.multicast++; 146 } 147 break; 148 case BR_PKT_UNICAST: 149 dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid); 150 default: 151 break; 152 } 153 154 if (dst) { 155 unsigned long now = jiffies; 156 157 if (test_bit(BR_FDB_LOCAL, &dst->flags)) 158 return br_pass_frame_up(skb); 159 160 if (now != dst->used) 161 dst->used = now; 162 br_forward(dst->dst, skb, local_rcv, false); 163 } else { 164 if (!mcast_hit) 165 br_flood(br, skb, pkt_type, local_rcv, false); 166 else 167 br_multicast_flood(mdst, skb, local_rcv, false); 168 } 169 170 if (local_rcv) 171 return br_pass_frame_up(skb); 172 173 out: 174 return 0; 175 drop: 176 kfree_skb(skb); 177 goto out; 178 } 179 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 180 181 static void __br_handle_local_finish(struct sk_buff *skb) 182 { 183 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 184 u16 vid = 0; 185 186 /* check if vlan is allowed, to avoid spoofing */ 187 if ((p->flags & BR_LEARNING) && 188 nbp_state_should_learn(p) && 189 !br_opt_get(p->br, BROPT_NO_LL_LEARN) && 190 br_should_learn(p, skb, &vid)) 191 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0); 192 } 193 194 /* note: already called with rcu_read_lock */ 195 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 196 { 197 __br_handle_local_finish(skb); 198 199 /* return 1 to signal the okfn() was called so it's ok to use the skb */ 200 return 1; 201 } 202 203 static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb) 204 { 205 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE 206 struct nf_hook_entries *e = NULL; 207 struct nf_hook_state state; 208 unsigned int verdict, i; 209 struct net *net; 210 int ret; 211 212 net = dev_net(skb->dev); 213 #ifdef HAVE_JUMP_LABEL 214 if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING])) 215 goto frame_finish; 216 #endif 217 218 e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]); 219 if (!e) 220 goto frame_finish; 221 222 nf_hook_state_init(&state, NF_BR_PRE_ROUTING, 223 NFPROTO_BRIDGE, skb->dev, NULL, NULL, 224 net, br_handle_frame_finish); 225 226 for (i = 0; i < e->num_hook_entries; i++) { 227 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state); 228 switch (verdict & NF_VERDICT_MASK) { 229 case NF_ACCEPT: 230 if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) { 231 *pskb = skb; 232 return RX_HANDLER_PASS; 233 } 234 break; 235 case NF_DROP: 236 kfree_skb(skb); 237 return RX_HANDLER_CONSUMED; 238 case NF_QUEUE: 239 ret = nf_queue(skb, &state, i, verdict); 240 if (ret == 1) 241 continue; 242 return RX_HANDLER_CONSUMED; 243 default: /* STOLEN */ 244 return RX_HANDLER_CONSUMED; 245 } 246 } 247 frame_finish: 248 net = dev_net(skb->dev); 249 br_handle_frame_finish(net, NULL, skb); 250 #else 251 br_handle_frame_finish(dev_net(skb->dev), NULL, skb); 252 #endif 253 return RX_HANDLER_CONSUMED; 254 } 255 256 /* 257 * Return NULL if skb is handled 258 * note: already called with rcu_read_lock 259 */ 260 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 261 { 262 struct net_bridge_port *p; 263 struct sk_buff *skb = *pskb; 264 const unsigned char *dest = eth_hdr(skb)->h_dest; 265 266 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 267 return RX_HANDLER_PASS; 268 269 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 270 goto drop; 271 272 skb = skb_share_check(skb, GFP_ATOMIC); 273 if (!skb) 274 return RX_HANDLER_CONSUMED; 275 276 memset(skb->cb, 0, sizeof(struct br_input_skb_cb)); 277 278 p = br_port_get_rcu(skb->dev); 279 if (p->flags & BR_VLAN_TUNNEL) { 280 if (br_handle_ingress_vlan_tunnel(skb, p, 281 nbp_vlan_group_rcu(p))) 282 goto drop; 283 } 284 285 if (unlikely(is_link_local_ether_addr(dest))) { 286 u16 fwd_mask = p->br->group_fwd_mask_required; 287 288 /* 289 * See IEEE 802.1D Table 7-10 Reserved addresses 290 * 291 * Assignment Value 292 * Bridge Group Address 01-80-C2-00-00-00 293 * (MAC Control) 802.3 01-80-C2-00-00-01 294 * (Link Aggregation) 802.3 01-80-C2-00-00-02 295 * 802.1X PAE address 01-80-C2-00-00-03 296 * 297 * 802.1AB LLDP 01-80-C2-00-00-0E 298 * 299 * Others reserved for future standardization 300 */ 301 fwd_mask |= p->group_fwd_mask; 302 switch (dest[5]) { 303 case 0x00: /* Bridge Group Address */ 304 /* If STP is turned off, 305 then must forward to keep loop detection */ 306 if (p->br->stp_enabled == BR_NO_STP || 307 fwd_mask & (1u << dest[5])) 308 goto forward; 309 *pskb = skb; 310 __br_handle_local_finish(skb); 311 return RX_HANDLER_PASS; 312 313 case 0x01: /* IEEE MAC (Pause) */ 314 goto drop; 315 316 case 0x0E: /* 802.1AB LLDP */ 317 fwd_mask |= p->br->group_fwd_mask; 318 if (fwd_mask & (1u << dest[5])) 319 goto forward; 320 *pskb = skb; 321 __br_handle_local_finish(skb); 322 return RX_HANDLER_PASS; 323 324 default: 325 /* Allow selective forwarding for most other protocols */ 326 fwd_mask |= p->br->group_fwd_mask; 327 if (fwd_mask & (1u << dest[5])) 328 goto forward; 329 } 330 331 /* The else clause should be hit when nf_hook(): 332 * - returns < 0 (drop/error) 333 * - returns = 0 (stolen/nf_queue) 334 * Thus return 1 from the okfn() to signal the skb is ok to pass 335 */ 336 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 337 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 338 br_handle_local_finish) == 1) { 339 return RX_HANDLER_PASS; 340 } else { 341 return RX_HANDLER_CONSUMED; 342 } 343 } 344 345 forward: 346 switch (p->state) { 347 case BR_STATE_FORWARDING: 348 case BR_STATE_LEARNING: 349 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 350 skb->pkt_type = PACKET_HOST; 351 352 return nf_hook_bridge_pre(skb, pskb); 353 default: 354 drop: 355 kfree_skb(skb); 356 } 357 return RX_HANDLER_CONSUMED; 358 } 359