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 !pskb_may_pull(skb, arp_hdr_len(dev))) 85 return; 86 87 parp = arp_hdr(skb); 88 89 if (parp->ar_pro != htons(ETH_P_IP) || 90 parp->ar_op != htons(ARPOP_REQUEST) || 91 parp->ar_hln != dev->addr_len || 92 parp->ar_pln != 4) 93 return; 94 95 arpptr = (u8 *)parp + sizeof(struct arphdr); 96 sha = arpptr; 97 arpptr += dev->addr_len; /* sha */ 98 memcpy(&sip, arpptr, sizeof(sip)); 99 arpptr += sizeof(sip); 100 arpptr += dev->addr_len; /* tha */ 101 memcpy(&tip, arpptr, sizeof(tip)); 102 103 if (ipv4_is_loopback(tip) || 104 ipv4_is_multicast(tip)) 105 return; 106 107 n = neigh_lookup(&arp_tbl, &tip, dev); 108 if (n) { 109 struct net_bridge_fdb_entry *f; 110 111 if (!(n->nud_state & NUD_VALID)) { 112 neigh_release(n); 113 return; 114 } 115 116 f = __br_fdb_get(br, n->ha, vid); 117 if (f && ((p->flags & BR_PROXYARP) || 118 (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) { 119 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip, 120 sha, n->ha, sha); 121 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true; 122 } 123 124 neigh_release(n); 125 } 126 } 127 128 /* note: already called with rcu_read_lock */ 129 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 130 { 131 bool local_rcv = false, mcast_hit = false, unicast = true; 132 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 133 const unsigned char *dest = eth_hdr(skb)->h_dest; 134 struct net_bridge_fdb_entry *dst = NULL; 135 struct net_bridge_mdb_entry *mdst; 136 struct net_bridge *br; 137 u16 vid = 0; 138 139 if (!p || p->state == BR_STATE_DISABLED) 140 goto drop; 141 142 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid)) 143 goto out; 144 145 /* insert into forwarding database after filtering to avoid spoofing */ 146 br = p->br; 147 if (p->flags & BR_LEARNING) 148 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false); 149 150 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) && 151 br_multicast_rcv(br, p, skb, vid)) 152 goto drop; 153 154 if (p->state == BR_STATE_LEARNING) 155 goto drop; 156 157 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 158 159 local_rcv = !!(br->dev->flags & IFF_PROMISC); 160 161 if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP)) 162 br_do_proxy_arp(skb, br, vid, p); 163 164 if (is_broadcast_ether_addr(dest)) { 165 local_rcv = true; 166 unicast = false; 167 } else if (is_multicast_ether_addr(dest)) { 168 mdst = br_mdb_get(br, skb, vid); 169 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 170 br_multicast_querier_exists(br, eth_hdr(skb))) { 171 if ((mdst && mdst->mglist) || 172 br_multicast_is_router(br)) { 173 local_rcv = true; 174 br->dev->stats.multicast++; 175 } 176 mcast_hit = true; 177 } else { 178 local_rcv = true; 179 br->dev->stats.multicast++; 180 } 181 unicast = false; 182 } else if ((dst = __br_fdb_get(br, dest, vid)) && dst->is_local) { 183 /* Do not forward the packet since it's local. */ 184 return br_pass_frame_up(skb); 185 } 186 187 if (dst) { 188 dst->used = jiffies; 189 br_forward(dst->dst, skb, local_rcv, false); 190 } else { 191 if (!mcast_hit) 192 br_flood(br, skb, unicast, local_rcv, false); 193 else 194 br_multicast_flood(mdst, skb, local_rcv, false); 195 } 196 197 if (local_rcv) 198 return br_pass_frame_up(skb); 199 200 out: 201 return 0; 202 drop: 203 kfree_skb(skb); 204 goto out; 205 } 206 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 207 208 static void __br_handle_local_finish(struct sk_buff *skb) 209 { 210 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 211 u16 vid = 0; 212 213 /* check if vlan is allowed, to avoid spoofing */ 214 if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid)) 215 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); 216 } 217 218 /* note: already called with rcu_read_lock */ 219 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 220 { 221 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 222 223 __br_handle_local_finish(skb); 224 225 BR_INPUT_SKB_CB(skb)->brdev = p->br->dev; 226 br_pass_frame_up(skb); 227 return 0; 228 } 229 230 /* 231 * Return NULL if skb is handled 232 * note: already called with rcu_read_lock 233 */ 234 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 235 { 236 struct net_bridge_port *p; 237 struct sk_buff *skb = *pskb; 238 const unsigned char *dest = eth_hdr(skb)->h_dest; 239 br_should_route_hook_t *rhook; 240 241 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 242 return RX_HANDLER_PASS; 243 244 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 245 goto drop; 246 247 skb = skb_share_check(skb, GFP_ATOMIC); 248 if (!skb) 249 return RX_HANDLER_CONSUMED; 250 251 p = br_port_get_rcu(skb->dev); 252 253 if (unlikely(is_link_local_ether_addr(dest))) { 254 u16 fwd_mask = p->br->group_fwd_mask_required; 255 256 /* 257 * See IEEE 802.1D Table 7-10 Reserved addresses 258 * 259 * Assignment Value 260 * Bridge Group Address 01-80-C2-00-00-00 261 * (MAC Control) 802.3 01-80-C2-00-00-01 262 * (Link Aggregation) 802.3 01-80-C2-00-00-02 263 * 802.1X PAE address 01-80-C2-00-00-03 264 * 265 * 802.1AB LLDP 01-80-C2-00-00-0E 266 * 267 * Others reserved for future standardization 268 */ 269 switch (dest[5]) { 270 case 0x00: /* Bridge Group Address */ 271 /* If STP is turned off, 272 then must forward to keep loop detection */ 273 if (p->br->stp_enabled == BR_NO_STP || 274 fwd_mask & (1u << dest[5])) 275 goto forward; 276 *pskb = skb; 277 __br_handle_local_finish(skb); 278 return RX_HANDLER_PASS; 279 280 case 0x01: /* IEEE MAC (Pause) */ 281 goto drop; 282 283 case 0x0E: /* 802.1AB LLDP */ 284 fwd_mask |= p->br->group_fwd_mask; 285 if (fwd_mask & (1u << dest[5])) 286 goto forward; 287 *pskb = skb; 288 __br_handle_local_finish(skb); 289 return RX_HANDLER_PASS; 290 291 default: 292 /* Allow selective forwarding for most other protocols */ 293 fwd_mask |= p->br->group_fwd_mask; 294 if (fwd_mask & (1u << dest[5])) 295 goto forward; 296 } 297 298 /* Deliver packet to local host only */ 299 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev), 300 NULL, skb, skb->dev, NULL, br_handle_local_finish); 301 return RX_HANDLER_CONSUMED; 302 } 303 304 forward: 305 switch (p->state) { 306 case BR_STATE_FORWARDING: 307 rhook = rcu_dereference(br_should_route_hook); 308 if (rhook) { 309 if ((*rhook)(skb)) { 310 *pskb = skb; 311 return RX_HANDLER_PASS; 312 } 313 dest = eth_hdr(skb)->h_dest; 314 } 315 /* fall through */ 316 case BR_STATE_LEARNING: 317 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 318 skb->pkt_type = PACKET_HOST; 319 320 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, 321 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 322 br_handle_frame_finish); 323 break; 324 default: 325 drop: 326 kfree_skb(skb); 327 } 328 return RX_HANDLER_CONSUMED; 329 } 330