1 /* 2 * Handle incoming frames 3 * Linux ethernet bridge 4 * 5 * Authors: 6 * Lennert Buytenhek <buytenh@gnu.org> 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License 10 * as published by the Free Software Foundation; either version 11 * 2 of the License, or (at your option) any later version. 12 */ 13 14 #include <linux/slab.h> 15 #include <linux/kernel.h> 16 #include <linux/netdevice.h> 17 #include <linux/etherdevice.h> 18 #include <linux/netfilter_bridge.h> 19 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE 20 #include <net/netfilter/nf_queue.h> 21 #endif 22 #include <linux/neighbour.h> 23 #include <net/arp.h> 24 #include <linux/export.h> 25 #include <linux/rculist.h> 26 #include "br_private.h" 27 #include "br_private_tunnel.h" 28 29 static int 30 br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb) 31 { 32 br_drop_fake_rtable(skb); 33 return netif_receive_skb(skb); 34 } 35 36 static int br_pass_frame_up(struct sk_buff *skb) 37 { 38 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; 39 struct net_bridge *br = netdev_priv(brdev); 40 struct net_bridge_vlan_group *vg; 41 struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats); 42 43 u64_stats_update_begin(&brstats->syncp); 44 brstats->rx_packets++; 45 brstats->rx_bytes += skb->len; 46 u64_stats_update_end(&brstats->syncp); 47 48 vg = br_vlan_group_rcu(br); 49 /* Bridge is just like any other port. Make sure the 50 * packet is allowed except in promisc modue when someone 51 * may be running packet capture. 52 */ 53 if (!(brdev->flags & IFF_PROMISC) && 54 !br_allowed_egress(vg, skb)) { 55 kfree_skb(skb); 56 return NET_RX_DROP; 57 } 58 59 indev = skb->dev; 60 skb->dev = brdev; 61 skb = br_handle_vlan(br, NULL, vg, skb); 62 if (!skb) 63 return NET_RX_DROP; 64 /* update the multicast stats if the packet is IGMP/MLD */ 65 br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb), 66 BR_MCAST_DIR_TX); 67 68 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 69 dev_net(indev), NULL, skb, indev, NULL, 70 br_netif_receive_skb); 71 } 72 73 /* note: already called with rcu_read_lock */ 74 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 75 { 76 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 77 enum br_pkt_type pkt_type = BR_PKT_UNICAST; 78 struct net_bridge_fdb_entry *dst = NULL; 79 struct net_bridge_mdb_entry *mdst; 80 bool local_rcv, mcast_hit = false; 81 const unsigned char *dest; 82 struct net_bridge *br; 83 u16 vid = 0; 84 85 if (!p || p->state == BR_STATE_DISABLED) 86 goto drop; 87 88 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid)) 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, false); 97 98 local_rcv = !!(br->dev->flags & IFF_PROMISC); 99 dest = eth_hdr(skb)->h_dest; 100 if (is_multicast_ether_addr(dest)) { 101 /* by definition the broadcast is also a multicast address */ 102 if (is_broadcast_ether_addr(dest)) { 103 pkt_type = BR_PKT_BROADCAST; 104 local_rcv = true; 105 } else { 106 pkt_type = BR_PKT_MULTICAST; 107 if (br_multicast_rcv(br, p, skb, vid)) 108 goto drop; 109 } 110 } 111 112 if (p->state == BR_STATE_LEARNING) 113 goto drop; 114 115 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 116 BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED); 117 118 if (IS_ENABLED(CONFIG_INET) && 119 (skb->protocol == htons(ETH_P_ARP) || 120 skb->protocol == htons(ETH_P_RARP))) { 121 br_do_proxy_suppress_arp(skb, br, vid, p); 122 } else if (IS_ENABLED(CONFIG_IPV6) && 123 skb->protocol == htons(ETH_P_IPV6) && 124 br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) && 125 pskb_may_pull(skb, sizeof(struct ipv6hdr) + 126 sizeof(struct nd_msg)) && 127 ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) { 128 struct nd_msg *msg, _msg; 129 130 msg = br_is_nd_neigh_msg(skb, &_msg); 131 if (msg) 132 br_do_suppress_nd(skb, br, vid, p, msg); 133 } 134 135 switch (pkt_type) { 136 case BR_PKT_MULTICAST: 137 mdst = br_mdb_get(br, skb, vid); 138 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 139 br_multicast_querier_exists(br, eth_hdr(skb))) { 140 if ((mdst && mdst->host_joined) || 141 br_multicast_is_router(br)) { 142 local_rcv = true; 143 br->dev->stats.multicast++; 144 } 145 mcast_hit = true; 146 } else { 147 local_rcv = true; 148 br->dev->stats.multicast++; 149 } 150 break; 151 case BR_PKT_UNICAST: 152 dst = br_fdb_find_rcu(br, dest, vid); 153 default: 154 break; 155 } 156 157 if (dst) { 158 unsigned long now = jiffies; 159 160 if (dst->is_local) 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, 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 !br_opt_get(p->br, BROPT_NO_LL_LEARN) && 192 br_should_learn(p, skb, &vid)) 193 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); 194 } 195 196 /* note: already called with rcu_read_lock */ 197 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 198 { 199 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 200 201 __br_handle_local_finish(skb); 202 203 BR_INPUT_SKB_CB(skb)->brdev = p->br->dev; 204 br_pass_frame_up(skb); 205 return 0; 206 } 207 208 static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb) 209 { 210 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE 211 struct nf_hook_entries *e = NULL; 212 struct nf_hook_state state; 213 unsigned int verdict, i; 214 struct net *net; 215 int ret; 216 217 net = dev_net(skb->dev); 218 #ifdef HAVE_JUMP_LABEL 219 if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING])) 220 goto frame_finish; 221 #endif 222 223 e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]); 224 if (!e) 225 goto frame_finish; 226 227 nf_hook_state_init(&state, NF_BR_PRE_ROUTING, 228 NFPROTO_BRIDGE, skb->dev, NULL, NULL, 229 net, br_handle_frame_finish); 230 231 for (i = 0; i < e->num_hook_entries; i++) { 232 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state); 233 switch (verdict & NF_VERDICT_MASK) { 234 case NF_ACCEPT: 235 if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) { 236 *pskb = skb; 237 return RX_HANDLER_PASS; 238 } 239 break; 240 case NF_DROP: 241 kfree_skb(skb); 242 return RX_HANDLER_CONSUMED; 243 case NF_QUEUE: 244 ret = nf_queue(skb, &state, e, i, verdict); 245 if (ret == 1) 246 continue; 247 return RX_HANDLER_CONSUMED; 248 default: /* STOLEN */ 249 return RX_HANDLER_CONSUMED; 250 } 251 } 252 frame_finish: 253 net = dev_net(skb->dev); 254 br_handle_frame_finish(net, NULL, skb); 255 #else 256 br_handle_frame_finish(dev_net(skb->dev), NULL, skb); 257 #endif 258 return RX_HANDLER_CONSUMED; 259 } 260 261 /* 262 * Return NULL if skb is handled 263 * note: already called with rcu_read_lock 264 */ 265 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 266 { 267 struct net_bridge_port *p; 268 struct sk_buff *skb = *pskb; 269 const unsigned char *dest = eth_hdr(skb)->h_dest; 270 271 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 272 return RX_HANDLER_PASS; 273 274 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 275 goto drop; 276 277 skb = skb_share_check(skb, GFP_ATOMIC); 278 if (!skb) 279 return RX_HANDLER_CONSUMED; 280 281 memset(skb->cb, 0, sizeof(struct br_input_skb_cb)); 282 283 p = br_port_get_rcu(skb->dev); 284 if (p->flags & BR_VLAN_TUNNEL) { 285 if (br_handle_ingress_vlan_tunnel(skb, p, 286 nbp_vlan_group_rcu(p))) 287 goto drop; 288 } 289 290 if (unlikely(is_link_local_ether_addr(dest))) { 291 u16 fwd_mask = p->br->group_fwd_mask_required; 292 293 /* 294 * See IEEE 802.1D Table 7-10 Reserved addresses 295 * 296 * Assignment Value 297 * Bridge Group Address 01-80-C2-00-00-00 298 * (MAC Control) 802.3 01-80-C2-00-00-01 299 * (Link Aggregation) 802.3 01-80-C2-00-00-02 300 * 802.1X PAE address 01-80-C2-00-00-03 301 * 302 * 802.1AB LLDP 01-80-C2-00-00-0E 303 * 304 * Others reserved for future standardization 305 */ 306 fwd_mask |= p->group_fwd_mask; 307 switch (dest[5]) { 308 case 0x00: /* Bridge Group Address */ 309 /* If STP is turned off, 310 then must forward to keep loop detection */ 311 if (p->br->stp_enabled == BR_NO_STP || 312 fwd_mask & (1u << dest[5])) 313 goto forward; 314 *pskb = skb; 315 __br_handle_local_finish(skb); 316 return RX_HANDLER_PASS; 317 318 case 0x01: /* IEEE MAC (Pause) */ 319 goto drop; 320 321 case 0x0E: /* 802.1AB LLDP */ 322 fwd_mask |= p->br->group_fwd_mask; 323 if (fwd_mask & (1u << dest[5])) 324 goto forward; 325 *pskb = skb; 326 __br_handle_local_finish(skb); 327 return RX_HANDLER_PASS; 328 329 default: 330 /* Allow selective forwarding for most other protocols */ 331 fwd_mask |= p->br->group_fwd_mask; 332 if (fwd_mask & (1u << dest[5])) 333 goto forward; 334 } 335 336 /* Deliver packet to local host only */ 337 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev), 338 NULL, skb, skb->dev, NULL, br_handle_local_finish); 339 return RX_HANDLER_CONSUMED; 340 } 341 342 forward: 343 switch (p->state) { 344 case BR_STATE_FORWARDING: 345 case BR_STATE_LEARNING: 346 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 347 skb->pkt_type = PACKET_HOST; 348 349 return nf_hook_bridge_pre(skb, pskb); 350 default: 351 drop: 352 kfree_skb(skb); 353 } 354 return RX_HANDLER_CONSUMED; 355 } 356