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 25 /* Hook for brouter */ 26 br_should_route_hook_t __rcu *br_should_route_hook __read_mostly; 27 EXPORT_SYMBOL(br_should_route_hook); 28 29 static int 30 br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb) 31 { 32 return netif_receive_skb(skb); 33 } 34 35 static int br_pass_frame_up(struct sk_buff *skb) 36 { 37 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; 38 struct net_bridge *br = netdev_priv(brdev); 39 struct net_bridge_vlan_group *vg; 40 struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats); 41 42 u64_stats_update_begin(&brstats->syncp); 43 brstats->rx_packets++; 44 brstats->rx_bytes += skb->len; 45 u64_stats_update_end(&brstats->syncp); 46 47 vg = br_vlan_group_rcu(br); 48 /* Bridge is just like any other port. Make sure the 49 * packet is allowed except in promisc modue when someone 50 * may be running packet capture. 51 */ 52 if (!(brdev->flags & IFF_PROMISC) && 53 !br_allowed_egress(vg, skb)) { 54 kfree_skb(skb); 55 return NET_RX_DROP; 56 } 57 58 indev = skb->dev; 59 skb->dev = brdev; 60 skb = br_handle_vlan(br, vg, skb); 61 if (!skb) 62 return NET_RX_DROP; 63 /* update the multicast stats if the packet is IGMP/MLD */ 64 br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb), 65 BR_MCAST_DIR_TX); 66 67 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 68 dev_net(indev), NULL, skb, indev, NULL, 69 br_netif_receive_skb); 70 } 71 72 static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br, 73 u16 vid, struct net_bridge_port *p) 74 { 75 struct net_device *dev = br->dev; 76 struct neighbour *n; 77 struct arphdr *parp; 78 u8 *arpptr, *sha; 79 __be32 sip, tip; 80 81 BR_INPUT_SKB_CB(skb)->proxyarp_replied = false; 82 83 if (dev->flags & IFF_NOARP) 84 return; 85 86 if (!pskb_may_pull(skb, arp_hdr_len(dev))) { 87 dev->stats.tx_dropped++; 88 return; 89 } 90 parp = arp_hdr(skb); 91 92 if (parp->ar_pro != htons(ETH_P_IP) || 93 parp->ar_op != htons(ARPOP_REQUEST) || 94 parp->ar_hln != dev->addr_len || 95 parp->ar_pln != 4) 96 return; 97 98 arpptr = (u8 *)parp + sizeof(struct arphdr); 99 sha = arpptr; 100 arpptr += dev->addr_len; /* sha */ 101 memcpy(&sip, arpptr, sizeof(sip)); 102 arpptr += sizeof(sip); 103 arpptr += dev->addr_len; /* tha */ 104 memcpy(&tip, arpptr, sizeof(tip)); 105 106 if (ipv4_is_loopback(tip) || 107 ipv4_is_multicast(tip)) 108 return; 109 110 n = neigh_lookup(&arp_tbl, &tip, dev); 111 if (n) { 112 struct net_bridge_fdb_entry *f; 113 114 if (!(n->nud_state & NUD_VALID)) { 115 neigh_release(n); 116 return; 117 } 118 119 f = __br_fdb_get(br, n->ha, vid); 120 if (f && ((p->flags & BR_PROXYARP) || 121 (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) { 122 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip, 123 sha, n->ha, sha); 124 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true; 125 } 126 127 neigh_release(n); 128 } 129 } 130 131 /* note: already called with rcu_read_lock */ 132 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 133 { 134 bool local_rcv = false, mcast_hit = false, unicast = true; 135 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 136 const unsigned char *dest = eth_hdr(skb)->h_dest; 137 struct net_bridge_fdb_entry *dst = NULL; 138 struct net_bridge_mdb_entry *mdst; 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 /* insert into forwarding database after filtering to avoid spoofing */ 149 br = p->br; 150 if (p->flags & BR_LEARNING) 151 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false); 152 153 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) && 154 br_multicast_rcv(br, p, skb, vid)) 155 goto drop; 156 157 if (p->state == BR_STATE_LEARNING) 158 goto drop; 159 160 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 161 162 local_rcv = !!(br->dev->flags & IFF_PROMISC); 163 164 if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP)) 165 br_do_proxy_arp(skb, br, vid, p); 166 167 if (is_broadcast_ether_addr(dest)) { 168 local_rcv = true; 169 unicast = false; 170 } else if (is_multicast_ether_addr(dest)) { 171 mdst = br_mdb_get(br, skb, vid); 172 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 173 br_multicast_querier_exists(br, eth_hdr(skb))) { 174 if ((mdst && mdst->mglist) || 175 br_multicast_is_router(br)) { 176 local_rcv = true; 177 br->dev->stats.multicast++; 178 } 179 mcast_hit = true; 180 } else { 181 local_rcv = true; 182 br->dev->stats.multicast++; 183 } 184 unicast = false; 185 } else if ((dst = __br_fdb_get(br, dest, vid)) && dst->is_local) { 186 /* Do not forward the packet since it's local. */ 187 return br_pass_frame_up(skb); 188 } 189 190 if (dst) { 191 dst->used = jiffies; 192 br_forward(dst->dst, skb, local_rcv, false); 193 } else { 194 if (!mcast_hit) 195 br_flood(br, skb, unicast, local_rcv, false); 196 else 197 br_multicast_flood(mdst, skb, local_rcv, false); 198 } 199 200 if (local_rcv) 201 return br_pass_frame_up(skb); 202 203 out: 204 return 0; 205 drop: 206 kfree_skb(skb); 207 goto out; 208 } 209 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 210 211 static void __br_handle_local_finish(struct sk_buff *skb) 212 { 213 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 214 u16 vid = 0; 215 216 /* check if vlan is allowed, to avoid spoofing */ 217 if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid)) 218 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); 219 } 220 221 /* note: already called with rcu_read_lock */ 222 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 223 { 224 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 225 226 __br_handle_local_finish(skb); 227 228 BR_INPUT_SKB_CB(skb)->brdev = p->br->dev; 229 br_pass_frame_up(skb); 230 return 0; 231 } 232 233 /* 234 * Return NULL if skb is handled 235 * note: already called with rcu_read_lock 236 */ 237 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 238 { 239 struct net_bridge_port *p; 240 struct sk_buff *skb = *pskb; 241 const unsigned char *dest = eth_hdr(skb)->h_dest; 242 br_should_route_hook_t *rhook; 243 244 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 245 return RX_HANDLER_PASS; 246 247 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 248 goto drop; 249 250 skb = skb_share_check(skb, GFP_ATOMIC); 251 if (!skb) 252 return RX_HANDLER_CONSUMED; 253 254 p = br_port_get_rcu(skb->dev); 255 256 if (unlikely(is_link_local_ether_addr(dest))) { 257 u16 fwd_mask = p->br->group_fwd_mask_required; 258 259 /* 260 * See IEEE 802.1D Table 7-10 Reserved addresses 261 * 262 * Assignment Value 263 * Bridge Group Address 01-80-C2-00-00-00 264 * (MAC Control) 802.3 01-80-C2-00-00-01 265 * (Link Aggregation) 802.3 01-80-C2-00-00-02 266 * 802.1X PAE address 01-80-C2-00-00-03 267 * 268 * 802.1AB LLDP 01-80-C2-00-00-0E 269 * 270 * Others reserved for future standardization 271 */ 272 switch (dest[5]) { 273 case 0x00: /* Bridge Group Address */ 274 /* If STP is turned off, 275 then must forward to keep loop detection */ 276 if (p->br->stp_enabled == BR_NO_STP || 277 fwd_mask & (1u << dest[5])) 278 goto forward; 279 *pskb = skb; 280 __br_handle_local_finish(skb); 281 return RX_HANDLER_PASS; 282 283 case 0x01: /* IEEE MAC (Pause) */ 284 goto drop; 285 286 case 0x0E: /* 802.1AB LLDP */ 287 fwd_mask |= p->br->group_fwd_mask; 288 if (fwd_mask & (1u << dest[5])) 289 goto forward; 290 *pskb = skb; 291 __br_handle_local_finish(skb); 292 return RX_HANDLER_PASS; 293 294 default: 295 /* Allow selective forwarding for most other protocols */ 296 fwd_mask |= p->br->group_fwd_mask; 297 if (fwd_mask & (1u << dest[5])) 298 goto forward; 299 } 300 301 /* Deliver packet to local host only */ 302 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev), 303 NULL, skb, skb->dev, NULL, br_handle_local_finish); 304 return RX_HANDLER_CONSUMED; 305 } 306 307 forward: 308 switch (p->state) { 309 case BR_STATE_FORWARDING: 310 rhook = rcu_dereference(br_should_route_hook); 311 if (rhook) { 312 if ((*rhook)(skb)) { 313 *pskb = skb; 314 return RX_HANDLER_PASS; 315 } 316 dest = eth_hdr(skb)->h_dest; 317 } 318 /* fall through */ 319 case BR_STATE_LEARNING: 320 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 321 skb->pkt_type = PACKET_HOST; 322 323 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, 324 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 325 br_handle_frame_finish); 326 break; 327 default: 328 drop: 329 kfree_skb(skb); 330 } 331 return RX_HANDLER_CONSUMED; 332 } 333