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