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 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 132 const unsigned char *dest = eth_hdr(skb)->h_dest; 133 enum br_pkt_type pkt_type = BR_PKT_UNICAST; 134 struct net_bridge_fdb_entry *dst = NULL; 135 struct net_bridge_mdb_entry *mdst; 136 bool local_rcv, mcast_hit = false; 137 struct net_bridge *br; 138 u16 vid = 0; 139 140 if (!p || p->state == BR_STATE_DISABLED) 141 goto drop; 142 143 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid)) 144 goto out; 145 146 nbp_switchdev_frame_mark(p, skb); 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 local_rcv = !!(br->dev->flags & IFF_PROMISC); 154 if (is_multicast_ether_addr(dest)) { 155 /* by definition the broadcast is also a multicast address */ 156 if (is_broadcast_ether_addr(dest)) { 157 pkt_type = BR_PKT_BROADCAST; 158 local_rcv = true; 159 } else { 160 pkt_type = BR_PKT_MULTICAST; 161 if (br_multicast_rcv(br, p, skb, vid)) 162 goto drop; 163 } 164 } 165 166 if (p->state == BR_STATE_LEARNING) 167 goto drop; 168 169 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 170 171 if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP)) 172 br_do_proxy_arp(skb, br, vid, p); 173 174 switch (pkt_type) { 175 case BR_PKT_MULTICAST: 176 mdst = br_mdb_get(br, skb, vid); 177 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 178 br_multicast_querier_exists(br, eth_hdr(skb))) { 179 if ((mdst && mdst->mglist) || 180 br_multicast_is_router(br)) { 181 local_rcv = true; 182 br->dev->stats.multicast++; 183 } 184 mcast_hit = true; 185 } else { 186 local_rcv = true; 187 br->dev->stats.multicast++; 188 } 189 break; 190 case BR_PKT_UNICAST: 191 dst = __br_fdb_get(br, dest, vid); 192 default: 193 break; 194 } 195 196 if (dst) { 197 if (dst->is_local) 198 return br_pass_frame_up(skb); 199 200 dst->used = jiffies; 201 br_forward(dst->dst, skb, local_rcv, false); 202 } else { 203 if (!mcast_hit) 204 br_flood(br, skb, pkt_type, local_rcv, false); 205 else 206 br_multicast_flood(mdst, skb, local_rcv, false); 207 } 208 209 if (local_rcv) 210 return br_pass_frame_up(skb); 211 212 out: 213 return 0; 214 drop: 215 kfree_skb(skb); 216 goto out; 217 } 218 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 219 220 static void __br_handle_local_finish(struct sk_buff *skb) 221 { 222 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 223 u16 vid = 0; 224 225 /* check if vlan is allowed, to avoid spoofing */ 226 if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid)) 227 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); 228 } 229 230 /* note: already called with rcu_read_lock */ 231 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 232 { 233 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 234 235 __br_handle_local_finish(skb); 236 237 BR_INPUT_SKB_CB(skb)->brdev = p->br->dev; 238 br_pass_frame_up(skb); 239 return 0; 240 } 241 242 /* 243 * Return NULL if skb is handled 244 * note: already called with rcu_read_lock 245 */ 246 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 247 { 248 struct net_bridge_port *p; 249 struct sk_buff *skb = *pskb; 250 const unsigned char *dest = eth_hdr(skb)->h_dest; 251 br_should_route_hook_t *rhook; 252 253 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 254 return RX_HANDLER_PASS; 255 256 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 257 goto drop; 258 259 skb = skb_share_check(skb, GFP_ATOMIC); 260 if (!skb) 261 return RX_HANDLER_CONSUMED; 262 263 p = br_port_get_rcu(skb->dev); 264 265 if (unlikely(is_link_local_ether_addr(dest))) { 266 u16 fwd_mask = p->br->group_fwd_mask_required; 267 268 /* 269 * See IEEE 802.1D Table 7-10 Reserved addresses 270 * 271 * Assignment Value 272 * Bridge Group Address 01-80-C2-00-00-00 273 * (MAC Control) 802.3 01-80-C2-00-00-01 274 * (Link Aggregation) 802.3 01-80-C2-00-00-02 275 * 802.1X PAE address 01-80-C2-00-00-03 276 * 277 * 802.1AB LLDP 01-80-C2-00-00-0E 278 * 279 * Others reserved for future standardization 280 */ 281 switch (dest[5]) { 282 case 0x00: /* Bridge Group Address */ 283 /* If STP is turned off, 284 then must forward to keep loop detection */ 285 if (p->br->stp_enabled == BR_NO_STP || 286 fwd_mask & (1u << dest[5])) 287 goto forward; 288 *pskb = skb; 289 __br_handle_local_finish(skb); 290 return RX_HANDLER_PASS; 291 292 case 0x01: /* IEEE MAC (Pause) */ 293 goto drop; 294 295 case 0x0E: /* 802.1AB LLDP */ 296 fwd_mask |= p->br->group_fwd_mask; 297 if (fwd_mask & (1u << dest[5])) 298 goto forward; 299 *pskb = skb; 300 __br_handle_local_finish(skb); 301 return RX_HANDLER_PASS; 302 303 default: 304 /* Allow selective forwarding for most other protocols */ 305 fwd_mask |= p->br->group_fwd_mask; 306 if (fwd_mask & (1u << dest[5])) 307 goto forward; 308 } 309 310 /* Deliver packet to local host only */ 311 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev), 312 NULL, skb, skb->dev, NULL, br_handle_local_finish); 313 return RX_HANDLER_CONSUMED; 314 } 315 316 forward: 317 switch (p->state) { 318 case BR_STATE_FORWARDING: 319 rhook = rcu_dereference(br_should_route_hook); 320 if (rhook) { 321 if ((*rhook)(skb)) { 322 *pskb = skb; 323 return RX_HANDLER_PASS; 324 } 325 dest = eth_hdr(skb)->h_dest; 326 } 327 /* fall through */ 328 case BR_STATE_LEARNING: 329 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 330 skb->pkt_type = PACKET_HOST; 331 332 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, 333 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 334 br_handle_frame_finish); 335 break; 336 default: 337 drop: 338 kfree_skb(skb); 339 } 340 return RX_HANDLER_CONSUMED; 341 } 342