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 #include <linux/neighbour.h> 20 #include <net/arp.h> 21 #include <linux/export.h> 22 #include <linux/rculist.h> 23 #include "br_private.h" 24 #include "br_private_tunnel.h" 25 26 /* Hook for brouter */ 27 br_should_route_hook_t __rcu *br_should_route_hook __read_mostly; 28 EXPORT_SYMBOL(br_should_route_hook); 29 30 static int 31 br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb) 32 { 33 br_drop_fake_rtable(skb); 34 return netif_receive_skb(skb); 35 } 36 37 static int br_pass_frame_up(struct sk_buff *skb) 38 { 39 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; 40 struct net_bridge *br = netdev_priv(brdev); 41 struct net_bridge_vlan_group *vg; 42 struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats); 43 44 u64_stats_update_begin(&brstats->syncp); 45 brstats->rx_packets++; 46 brstats->rx_bytes += skb->len; 47 u64_stats_update_end(&brstats->syncp); 48 49 vg = br_vlan_group_rcu(br); 50 /* Bridge is just like any other port. Make sure the 51 * packet is allowed except in promisc modue when someone 52 * may be running packet capture. 53 */ 54 if (!(brdev->flags & IFF_PROMISC) && 55 !br_allowed_egress(vg, skb)) { 56 kfree_skb(skb); 57 return NET_RX_DROP; 58 } 59 60 indev = skb->dev; 61 skb->dev = brdev; 62 skb = br_handle_vlan(br, NULL, vg, skb); 63 if (!skb) 64 return NET_RX_DROP; 65 /* update the multicast stats if the packet is IGMP/MLD */ 66 br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb), 67 BR_MCAST_DIR_TX); 68 69 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 70 dev_net(indev), NULL, skb, indev, NULL, 71 br_netif_receive_skb); 72 } 73 74 static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br, 75 u16 vid, struct net_bridge_port *p) 76 { 77 struct net_device *dev = br->dev; 78 struct neighbour *n; 79 struct arphdr *parp; 80 u8 *arpptr, *sha; 81 __be32 sip, tip; 82 83 BR_INPUT_SKB_CB(skb)->proxyarp_replied = false; 84 85 if ((dev->flags & IFF_NOARP) || 86 !pskb_may_pull(skb, arp_hdr_len(dev))) 87 return; 88 89 parp = arp_hdr(skb); 90 91 if (parp->ar_pro != htons(ETH_P_IP) || 92 parp->ar_op != htons(ARPOP_REQUEST) || 93 parp->ar_hln != dev->addr_len || 94 parp->ar_pln != 4) 95 return; 96 97 arpptr = (u8 *)parp + sizeof(struct arphdr); 98 sha = arpptr; 99 arpptr += dev->addr_len; /* sha */ 100 memcpy(&sip, arpptr, sizeof(sip)); 101 arpptr += sizeof(sip); 102 arpptr += dev->addr_len; /* tha */ 103 memcpy(&tip, arpptr, sizeof(tip)); 104 105 if (ipv4_is_loopback(tip) || 106 ipv4_is_multicast(tip)) 107 return; 108 109 n = neigh_lookup(&arp_tbl, &tip, dev); 110 if (n) { 111 struct net_bridge_fdb_entry *f; 112 113 if (!(n->nud_state & NUD_VALID)) { 114 neigh_release(n); 115 return; 116 } 117 118 f = br_fdb_find_rcu(br, n->ha, vid); 119 if (f && ((p->flags & BR_PROXYARP) || 120 (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) { 121 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip, 122 sha, n->ha, sha); 123 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true; 124 } 125 126 neigh_release(n); 127 } 128 } 129 130 /* note: already called with rcu_read_lock */ 131 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 132 { 133 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 134 const unsigned char *dest = eth_hdr(skb)->h_dest; 135 enum br_pkt_type pkt_type = BR_PKT_UNICAST; 136 struct net_bridge_fdb_entry *dst = NULL; 137 struct net_bridge_mdb_entry *mdst; 138 bool local_rcv, mcast_hit = false; 139 struct net_bridge *br; 140 u16 vid = 0; 141 142 if (!p || p->state == BR_STATE_DISABLED) 143 goto drop; 144 145 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid)) 146 goto out; 147 148 nbp_switchdev_frame_mark(p, skb); 149 150 /* insert into forwarding database after filtering to avoid spoofing */ 151 br = p->br; 152 if (p->flags & BR_LEARNING) 153 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false); 154 155 local_rcv = !!(br->dev->flags & IFF_PROMISC); 156 if (is_multicast_ether_addr(dest)) { 157 /* by definition the broadcast is also a multicast address */ 158 if (is_broadcast_ether_addr(dest)) { 159 pkt_type = BR_PKT_BROADCAST; 160 local_rcv = true; 161 } else { 162 pkt_type = BR_PKT_MULTICAST; 163 if (br_multicast_rcv(br, p, skb, vid)) 164 goto drop; 165 } 166 } 167 168 if (p->state == BR_STATE_LEARNING) 169 goto drop; 170 171 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 172 173 if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP)) 174 br_do_proxy_arp(skb, br, vid, p); 175 176 switch (pkt_type) { 177 case BR_PKT_MULTICAST: 178 mdst = br_mdb_get(br, skb, vid); 179 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 180 br_multicast_querier_exists(br, eth_hdr(skb))) { 181 if ((mdst && mdst->mglist) || 182 br_multicast_is_router(br)) { 183 local_rcv = true; 184 br->dev->stats.multicast++; 185 } 186 mcast_hit = true; 187 } else { 188 local_rcv = true; 189 br->dev->stats.multicast++; 190 } 191 break; 192 case BR_PKT_UNICAST: 193 dst = br_fdb_find_rcu(br, dest, vid); 194 default: 195 break; 196 } 197 198 if (dst) { 199 unsigned long now = jiffies; 200 201 if (dst->is_local) 202 return br_pass_frame_up(skb); 203 204 if (now != dst->used) 205 dst->used = now; 206 br_forward(dst->dst, skb, local_rcv, false); 207 } else { 208 if (!mcast_hit) 209 br_flood(br, skb, pkt_type, local_rcv, false); 210 else 211 br_multicast_flood(mdst, skb, local_rcv, false); 212 } 213 214 if (local_rcv) 215 return br_pass_frame_up(skb); 216 217 out: 218 return 0; 219 drop: 220 kfree_skb(skb); 221 goto out; 222 } 223 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 224 225 static void __br_handle_local_finish(struct sk_buff *skb) 226 { 227 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 228 u16 vid = 0; 229 230 /* check if vlan is allowed, to avoid spoofing */ 231 if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid)) 232 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); 233 } 234 235 /* note: already called with rcu_read_lock */ 236 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 237 { 238 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 239 240 __br_handle_local_finish(skb); 241 242 BR_INPUT_SKB_CB(skb)->brdev = p->br->dev; 243 br_pass_frame_up(skb); 244 return 0; 245 } 246 247 /* 248 * Return NULL if skb is handled 249 * note: already called with rcu_read_lock 250 */ 251 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 252 { 253 struct net_bridge_port *p; 254 struct sk_buff *skb = *pskb; 255 const unsigned char *dest = eth_hdr(skb)->h_dest; 256 br_should_route_hook_t *rhook; 257 258 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 259 return RX_HANDLER_PASS; 260 261 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 262 goto drop; 263 264 skb = skb_share_check(skb, GFP_ATOMIC); 265 if (!skb) 266 return RX_HANDLER_CONSUMED; 267 268 p = br_port_get_rcu(skb->dev); 269 if (p->flags & BR_VLAN_TUNNEL) { 270 if (br_handle_ingress_vlan_tunnel(skb, p, 271 nbp_vlan_group_rcu(p))) 272 goto drop; 273 } 274 275 if (unlikely(is_link_local_ether_addr(dest))) { 276 u16 fwd_mask = p->br->group_fwd_mask_required; 277 278 /* 279 * See IEEE 802.1D Table 7-10 Reserved addresses 280 * 281 * Assignment Value 282 * Bridge Group Address 01-80-C2-00-00-00 283 * (MAC Control) 802.3 01-80-C2-00-00-01 284 * (Link Aggregation) 802.3 01-80-C2-00-00-02 285 * 802.1X PAE address 01-80-C2-00-00-03 286 * 287 * 802.1AB LLDP 01-80-C2-00-00-0E 288 * 289 * Others reserved for future standardization 290 */ 291 switch (dest[5]) { 292 case 0x00: /* Bridge Group Address */ 293 /* If STP is turned off, 294 then must forward to keep loop detection */ 295 if (p->br->stp_enabled == BR_NO_STP || 296 fwd_mask & (1u << dest[5])) 297 goto forward; 298 *pskb = skb; 299 __br_handle_local_finish(skb); 300 return RX_HANDLER_PASS; 301 302 case 0x01: /* IEEE MAC (Pause) */ 303 goto drop; 304 305 case 0x0E: /* 802.1AB LLDP */ 306 fwd_mask |= p->br->group_fwd_mask; 307 if (fwd_mask & (1u << dest[5])) 308 goto forward; 309 *pskb = skb; 310 __br_handle_local_finish(skb); 311 return RX_HANDLER_PASS; 312 313 default: 314 /* Allow selective forwarding for most other protocols */ 315 fwd_mask |= p->br->group_fwd_mask; 316 if (fwd_mask & (1u << dest[5])) 317 goto forward; 318 } 319 320 /* Deliver packet to local host only */ 321 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev), 322 NULL, skb, skb->dev, NULL, br_handle_local_finish); 323 return RX_HANDLER_CONSUMED; 324 } 325 326 forward: 327 switch (p->state) { 328 case BR_STATE_FORWARDING: 329 rhook = rcu_dereference(br_should_route_hook); 330 if (rhook) { 331 if ((*rhook)(skb)) { 332 *pskb = skb; 333 return RX_HANDLER_PASS; 334 } 335 dest = eth_hdr(skb)->h_dest; 336 } 337 /* fall through */ 338 case BR_STATE_LEARNING: 339 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 340 skb->pkt_type = PACKET_HOST; 341 342 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, 343 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 344 br_handle_frame_finish); 345 break; 346 default: 347 drop: 348 kfree_skb(skb); 349 } 350 return RX_HANDLER_CONSUMED; 351 } 352