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 __br_handle_local_finish(skb); 200 201 /* return 1 to signal the okfn() was called so it's ok to use the skb */ 202 return 1; 203 } 204 205 static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb) 206 { 207 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE 208 struct nf_hook_entries *e = NULL; 209 struct nf_hook_state state; 210 unsigned int verdict, i; 211 struct net *net; 212 int ret; 213 214 net = dev_net(skb->dev); 215 #ifdef HAVE_JUMP_LABEL 216 if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING])) 217 goto frame_finish; 218 #endif 219 220 e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]); 221 if (!e) 222 goto frame_finish; 223 224 nf_hook_state_init(&state, NF_BR_PRE_ROUTING, 225 NFPROTO_BRIDGE, skb->dev, NULL, NULL, 226 net, br_handle_frame_finish); 227 228 for (i = 0; i < e->num_hook_entries; i++) { 229 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state); 230 switch (verdict & NF_VERDICT_MASK) { 231 case NF_ACCEPT: 232 if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) { 233 *pskb = skb; 234 return RX_HANDLER_PASS; 235 } 236 break; 237 case NF_DROP: 238 kfree_skb(skb); 239 return RX_HANDLER_CONSUMED; 240 case NF_QUEUE: 241 ret = nf_queue(skb, &state, e, i, verdict); 242 if (ret == 1) 243 continue; 244 return RX_HANDLER_CONSUMED; 245 default: /* STOLEN */ 246 return RX_HANDLER_CONSUMED; 247 } 248 } 249 frame_finish: 250 net = dev_net(skb->dev); 251 br_handle_frame_finish(net, NULL, skb); 252 #else 253 br_handle_frame_finish(dev_net(skb->dev), NULL, skb); 254 #endif 255 return RX_HANDLER_CONSUMED; 256 } 257 258 /* 259 * Return NULL if skb is handled 260 * note: already called with rcu_read_lock 261 */ 262 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 263 { 264 struct net_bridge_port *p; 265 struct sk_buff *skb = *pskb; 266 const unsigned char *dest = eth_hdr(skb)->h_dest; 267 268 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 269 return RX_HANDLER_PASS; 270 271 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 272 goto drop; 273 274 skb = skb_share_check(skb, GFP_ATOMIC); 275 if (!skb) 276 return RX_HANDLER_CONSUMED; 277 278 memset(skb->cb, 0, sizeof(struct br_input_skb_cb)); 279 280 p = br_port_get_rcu(skb->dev); 281 if (p->flags & BR_VLAN_TUNNEL) { 282 if (br_handle_ingress_vlan_tunnel(skb, p, 283 nbp_vlan_group_rcu(p))) 284 goto drop; 285 } 286 287 if (unlikely(is_link_local_ether_addr(dest))) { 288 u16 fwd_mask = p->br->group_fwd_mask_required; 289 290 /* 291 * See IEEE 802.1D Table 7-10 Reserved addresses 292 * 293 * Assignment Value 294 * Bridge Group Address 01-80-C2-00-00-00 295 * (MAC Control) 802.3 01-80-C2-00-00-01 296 * (Link Aggregation) 802.3 01-80-C2-00-00-02 297 * 802.1X PAE address 01-80-C2-00-00-03 298 * 299 * 802.1AB LLDP 01-80-C2-00-00-0E 300 * 301 * Others reserved for future standardization 302 */ 303 fwd_mask |= p->group_fwd_mask; 304 switch (dest[5]) { 305 case 0x00: /* Bridge Group Address */ 306 /* If STP is turned off, 307 then must forward to keep loop detection */ 308 if (p->br->stp_enabled == BR_NO_STP || 309 fwd_mask & (1u << dest[5])) 310 goto forward; 311 *pskb = skb; 312 __br_handle_local_finish(skb); 313 return RX_HANDLER_PASS; 314 315 case 0x01: /* IEEE MAC (Pause) */ 316 goto drop; 317 318 case 0x0E: /* 802.1AB LLDP */ 319 fwd_mask |= p->br->group_fwd_mask; 320 if (fwd_mask & (1u << dest[5])) 321 goto forward; 322 *pskb = skb; 323 __br_handle_local_finish(skb); 324 return RX_HANDLER_PASS; 325 326 default: 327 /* Allow selective forwarding for most other protocols */ 328 fwd_mask |= p->br->group_fwd_mask; 329 if (fwd_mask & (1u << dest[5])) 330 goto forward; 331 } 332 333 /* The else clause should be hit when nf_hook(): 334 * - returns < 0 (drop/error) 335 * - returns = 0 (stolen/nf_queue) 336 * Thus return 1 from the okfn() to signal the skb is ok to pass 337 */ 338 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 339 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 340 br_handle_local_finish) == 1) { 341 return RX_HANDLER_PASS; 342 } else { 343 return RX_HANDLER_CONSUMED; 344 } 345 } 346 347 forward: 348 switch (p->state) { 349 case BR_STATE_FORWARDING: 350 case BR_STATE_LEARNING: 351 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 352 skb->pkt_type = PACKET_HOST; 353 354 return nf_hook_bridge_pre(skb, pskb); 355 default: 356 drop: 357 kfree_skb(skb); 358 } 359 return RX_HANDLER_CONSUMED; 360 } 361