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 80 if (!p || p->state == BR_STATE_DISABLED) 81 goto drop; 82 83 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid)) 84 goto out; 85 86 nbp_switchdev_frame_mark(p, skb); 87 88 /* insert into forwarding database after filtering to avoid spoofing */ 89 br = p->br; 90 if (p->flags & BR_LEARNING) 91 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false); 92 93 local_rcv = !!(br->dev->flags & IFF_PROMISC); 94 if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) { 95 /* by definition the broadcast is also a multicast address */ 96 if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) { 97 pkt_type = BR_PKT_BROADCAST; 98 local_rcv = true; 99 } else { 100 pkt_type = BR_PKT_MULTICAST; 101 if (br_multicast_rcv(br, p, skb, vid)) 102 goto drop; 103 } 104 } 105 106 if (p->state == BR_STATE_LEARNING) 107 goto drop; 108 109 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 110 BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED); 111 112 if (IS_ENABLED(CONFIG_INET) && 113 (skb->protocol == htons(ETH_P_ARP) || 114 skb->protocol == htons(ETH_P_RARP))) { 115 br_do_proxy_suppress_arp(skb, br, vid, p); 116 } else if (IS_ENABLED(CONFIG_IPV6) && 117 skb->protocol == htons(ETH_P_IPV6) && 118 br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) && 119 pskb_may_pull(skb, sizeof(struct ipv6hdr) + 120 sizeof(struct nd_msg)) && 121 ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) { 122 struct nd_msg *msg, _msg; 123 124 msg = br_is_nd_neigh_msg(skb, &_msg); 125 if (msg) 126 br_do_suppress_nd(skb, br, vid, p, msg); 127 } 128 129 switch (pkt_type) { 130 case BR_PKT_MULTICAST: 131 mdst = br_mdb_get(br, skb, vid); 132 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 133 br_multicast_querier_exists(br, eth_hdr(skb))) { 134 if ((mdst && mdst->host_joined) || 135 br_multicast_is_router(br)) { 136 local_rcv = true; 137 br->dev->stats.multicast++; 138 } 139 mcast_hit = true; 140 } else { 141 local_rcv = true; 142 br->dev->stats.multicast++; 143 } 144 break; 145 case BR_PKT_UNICAST: 146 dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid); 147 default: 148 break; 149 } 150 151 if (dst) { 152 unsigned long now = jiffies; 153 154 if (dst->is_local) 155 return br_pass_frame_up(skb); 156 157 if (now != dst->used) 158 dst->used = now; 159 br_forward(dst->dst, skb, local_rcv, false); 160 } else { 161 if (!mcast_hit) 162 br_flood(br, skb, pkt_type, local_rcv, false); 163 else 164 br_multicast_flood(mdst, skb, local_rcv, false); 165 } 166 167 if (local_rcv) 168 return br_pass_frame_up(skb); 169 170 out: 171 return 0; 172 drop: 173 kfree_skb(skb); 174 goto out; 175 } 176 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 177 178 static void __br_handle_local_finish(struct sk_buff *skb) 179 { 180 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 181 u16 vid = 0; 182 183 /* check if vlan is allowed, to avoid spoofing */ 184 if ((p->flags & BR_LEARNING) && 185 !br_opt_get(p->br, BROPT_NO_LL_LEARN) && 186 br_should_learn(p, skb, &vid)) 187 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); 188 } 189 190 /* note: already called with rcu_read_lock */ 191 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 192 { 193 __br_handle_local_finish(skb); 194 195 /* return 1 to signal the okfn() was called so it's ok to use the skb */ 196 return 1; 197 } 198 199 static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb) 200 { 201 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE 202 struct nf_hook_entries *e = NULL; 203 struct nf_hook_state state; 204 unsigned int verdict, i; 205 struct net *net; 206 int ret; 207 208 net = dev_net(skb->dev); 209 #ifdef HAVE_JUMP_LABEL 210 if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING])) 211 goto frame_finish; 212 #endif 213 214 e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]); 215 if (!e) 216 goto frame_finish; 217 218 nf_hook_state_init(&state, NF_BR_PRE_ROUTING, 219 NFPROTO_BRIDGE, skb->dev, NULL, NULL, 220 net, br_handle_frame_finish); 221 222 for (i = 0; i < e->num_hook_entries; i++) { 223 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state); 224 switch (verdict & NF_VERDICT_MASK) { 225 case NF_ACCEPT: 226 if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) { 227 *pskb = skb; 228 return RX_HANDLER_PASS; 229 } 230 break; 231 case NF_DROP: 232 kfree_skb(skb); 233 return RX_HANDLER_CONSUMED; 234 case NF_QUEUE: 235 ret = nf_queue(skb, &state, i, verdict); 236 if (ret == 1) 237 continue; 238 return RX_HANDLER_CONSUMED; 239 default: /* STOLEN */ 240 return RX_HANDLER_CONSUMED; 241 } 242 } 243 frame_finish: 244 net = dev_net(skb->dev); 245 br_handle_frame_finish(net, NULL, skb); 246 #else 247 br_handle_frame_finish(dev_net(skb->dev), NULL, skb); 248 #endif 249 return RX_HANDLER_CONSUMED; 250 } 251 252 /* 253 * Return NULL if skb is handled 254 * note: already called with rcu_read_lock 255 */ 256 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 257 { 258 struct net_bridge_port *p; 259 struct sk_buff *skb = *pskb; 260 const unsigned char *dest = eth_hdr(skb)->h_dest; 261 262 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 263 return RX_HANDLER_PASS; 264 265 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 266 goto drop; 267 268 skb = skb_share_check(skb, GFP_ATOMIC); 269 if (!skb) 270 return RX_HANDLER_CONSUMED; 271 272 memset(skb->cb, 0, sizeof(struct br_input_skb_cb)); 273 274 p = br_port_get_rcu(skb->dev); 275 if (p->flags & BR_VLAN_TUNNEL) { 276 if (br_handle_ingress_vlan_tunnel(skb, p, 277 nbp_vlan_group_rcu(p))) 278 goto drop; 279 } 280 281 if (unlikely(is_link_local_ether_addr(dest))) { 282 u16 fwd_mask = p->br->group_fwd_mask_required; 283 284 /* 285 * See IEEE 802.1D Table 7-10 Reserved addresses 286 * 287 * Assignment Value 288 * Bridge Group Address 01-80-C2-00-00-00 289 * (MAC Control) 802.3 01-80-C2-00-00-01 290 * (Link Aggregation) 802.3 01-80-C2-00-00-02 291 * 802.1X PAE address 01-80-C2-00-00-03 292 * 293 * 802.1AB LLDP 01-80-C2-00-00-0E 294 * 295 * Others reserved for future standardization 296 */ 297 fwd_mask |= p->group_fwd_mask; 298 switch (dest[5]) { 299 case 0x00: /* Bridge Group Address */ 300 /* If STP is turned off, 301 then must forward to keep loop detection */ 302 if (p->br->stp_enabled == BR_NO_STP || 303 fwd_mask & (1u << dest[5])) 304 goto forward; 305 *pskb = skb; 306 __br_handle_local_finish(skb); 307 return RX_HANDLER_PASS; 308 309 case 0x01: /* IEEE MAC (Pause) */ 310 goto drop; 311 312 case 0x0E: /* 802.1AB LLDP */ 313 fwd_mask |= p->br->group_fwd_mask; 314 if (fwd_mask & (1u << dest[5])) 315 goto forward; 316 *pskb = skb; 317 __br_handle_local_finish(skb); 318 return RX_HANDLER_PASS; 319 320 default: 321 /* Allow selective forwarding for most other protocols */ 322 fwd_mask |= p->br->group_fwd_mask; 323 if (fwd_mask & (1u << dest[5])) 324 goto forward; 325 } 326 327 /* The else clause should be hit when nf_hook(): 328 * - returns < 0 (drop/error) 329 * - returns = 0 (stolen/nf_queue) 330 * Thus return 1 from the okfn() to signal the skb is ok to pass 331 */ 332 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 333 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 334 br_handle_local_finish) == 1) { 335 return RX_HANDLER_PASS; 336 } else { 337 return RX_HANDLER_CONSUMED; 338 } 339 } 340 341 forward: 342 switch (p->state) { 343 case BR_STATE_FORWARDING: 344 case BR_STATE_LEARNING: 345 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 346 skb->pkt_type = PACKET_HOST; 347 348 return nf_hook_bridge_pre(skb, pskb); 349 default: 350 drop: 351 kfree_skb(skb); 352 } 353 return RX_HANDLER_CONSUMED; 354 } 355