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 br_pass_frame_up(struct sk_buff *skb) 30 { 31 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; 32 struct net_bridge *br = netdev_priv(brdev); 33 struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats); 34 struct net_port_vlans *pv; 35 36 u64_stats_update_begin(&brstats->syncp); 37 brstats->rx_packets++; 38 brstats->rx_bytes += skb->len; 39 u64_stats_update_end(&brstats->syncp); 40 41 /* Bridge is just like any other port. Make sure the 42 * packet is allowed except in promisc modue when someone 43 * may be running packet capture. 44 */ 45 pv = br_get_vlan_info(br); 46 if (!(brdev->flags & IFF_PROMISC) && 47 !br_allowed_egress(br, pv, skb)) { 48 kfree_skb(skb); 49 return NET_RX_DROP; 50 } 51 52 indev = skb->dev; 53 skb->dev = brdev; 54 skb = br_handle_vlan(br, pv, skb); 55 if (!skb) 56 return NET_RX_DROP; 57 58 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL, 59 netif_receive_skb); 60 } 61 62 static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br, 63 u16 vid) 64 { 65 struct net_device *dev = br->dev; 66 struct neighbour *n; 67 struct arphdr *parp; 68 u8 *arpptr, *sha; 69 __be32 sip, tip; 70 71 if (dev->flags & IFF_NOARP) 72 return; 73 74 if (!pskb_may_pull(skb, arp_hdr_len(dev))) { 75 dev->stats.tx_dropped++; 76 return; 77 } 78 parp = arp_hdr(skb); 79 80 if (parp->ar_pro != htons(ETH_P_IP) || 81 parp->ar_op != htons(ARPOP_REQUEST) || 82 parp->ar_hln != dev->addr_len || 83 parp->ar_pln != 4) 84 return; 85 86 arpptr = (u8 *)parp + sizeof(struct arphdr); 87 sha = arpptr; 88 arpptr += dev->addr_len; /* sha */ 89 memcpy(&sip, arpptr, sizeof(sip)); 90 arpptr += sizeof(sip); 91 arpptr += dev->addr_len; /* tha */ 92 memcpy(&tip, arpptr, sizeof(tip)); 93 94 if (ipv4_is_loopback(tip) || 95 ipv4_is_multicast(tip)) 96 return; 97 98 n = neigh_lookup(&arp_tbl, &tip, dev); 99 if (n) { 100 struct net_bridge_fdb_entry *f; 101 102 if (!(n->nud_state & NUD_VALID)) { 103 neigh_release(n); 104 return; 105 } 106 107 f = __br_fdb_get(br, n->ha, vid); 108 if (f) 109 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip, 110 sha, n->ha, sha); 111 112 neigh_release(n); 113 } 114 } 115 116 /* note: already called with rcu_read_lock */ 117 int br_handle_frame_finish(struct sk_buff *skb) 118 { 119 const unsigned char *dest = eth_hdr(skb)->h_dest; 120 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 121 struct net_bridge *br; 122 struct net_bridge_fdb_entry *dst; 123 struct net_bridge_mdb_entry *mdst; 124 struct sk_buff *skb2; 125 bool unicast = true; 126 u16 vid = 0; 127 128 if (!p || p->state == BR_STATE_DISABLED) 129 goto drop; 130 131 if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb, &vid)) 132 goto out; 133 134 /* insert into forwarding database after filtering to avoid spoofing */ 135 br = p->br; 136 if (p->flags & BR_LEARNING) 137 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false); 138 139 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) && 140 br_multicast_rcv(br, p, skb, vid)) 141 goto drop; 142 143 if (p->state == BR_STATE_LEARNING) 144 goto drop; 145 146 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 147 148 /* The packet skb2 goes to the local host (NULL to skip). */ 149 skb2 = NULL; 150 151 if (br->dev->flags & IFF_PROMISC) 152 skb2 = skb; 153 154 dst = NULL; 155 156 if (is_broadcast_ether_addr(dest)) { 157 if (p->flags & BR_PROXYARP && 158 skb->protocol == htons(ETH_P_ARP)) 159 br_do_proxy_arp(skb, br, vid); 160 161 skb2 = skb; 162 unicast = false; 163 } else if (is_multicast_ether_addr(dest)) { 164 mdst = br_mdb_get(br, skb, vid); 165 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 166 br_multicast_querier_exists(br, eth_hdr(skb))) { 167 if ((mdst && mdst->mglist) || 168 br_multicast_is_router(br)) 169 skb2 = skb; 170 br_multicast_forward(mdst, skb, skb2); 171 skb = NULL; 172 if (!skb2) 173 goto out; 174 } else 175 skb2 = skb; 176 177 unicast = false; 178 br->dev->stats.multicast++; 179 } else if ((dst = __br_fdb_get(br, dest, vid)) && 180 dst->is_local) { 181 skb2 = skb; 182 /* Do not forward the packet since it's local. */ 183 skb = NULL; 184 } 185 186 if (skb) { 187 if (dst) { 188 dst->used = jiffies; 189 br_forward(dst->dst, skb, skb2); 190 } else 191 br_flood_forward(br, skb, skb2, unicast); 192 } 193 194 if (skb2) 195 return br_pass_frame_up(skb2); 196 197 out: 198 return 0; 199 drop: 200 kfree_skb(skb); 201 goto out; 202 } 203 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 204 205 /* note: already called with rcu_read_lock */ 206 static int br_handle_local_finish(struct sk_buff *skb) 207 { 208 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 209 u16 vid = 0; 210 211 /* check if vlan is allowed, to avoid spoofing */ 212 if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid)) 213 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); 214 return 0; /* process further */ 215 } 216 217 /* 218 * Return NULL if skb is handled 219 * note: already called with rcu_read_lock 220 */ 221 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 222 { 223 struct net_bridge_port *p; 224 struct sk_buff *skb = *pskb; 225 const unsigned char *dest = eth_hdr(skb)->h_dest; 226 br_should_route_hook_t *rhook; 227 228 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 229 return RX_HANDLER_PASS; 230 231 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 232 goto drop; 233 234 skb = skb_share_check(skb, GFP_ATOMIC); 235 if (!skb) 236 return RX_HANDLER_CONSUMED; 237 238 p = br_port_get_rcu(skb->dev); 239 240 if (unlikely(is_link_local_ether_addr(dest))) { 241 u16 fwd_mask = p->br->group_fwd_mask_required; 242 243 /* 244 * See IEEE 802.1D Table 7-10 Reserved addresses 245 * 246 * Assignment Value 247 * Bridge Group Address 01-80-C2-00-00-00 248 * (MAC Control) 802.3 01-80-C2-00-00-01 249 * (Link Aggregation) 802.3 01-80-C2-00-00-02 250 * 802.1X PAE address 01-80-C2-00-00-03 251 * 252 * 802.1AB LLDP 01-80-C2-00-00-0E 253 * 254 * Others reserved for future standardization 255 */ 256 switch (dest[5]) { 257 case 0x00: /* Bridge Group Address */ 258 /* If STP is turned off, 259 then must forward to keep loop detection */ 260 if (p->br->stp_enabled == BR_NO_STP || 261 fwd_mask & (1u << dest[5])) 262 goto forward; 263 break; 264 265 case 0x01: /* IEEE MAC (Pause) */ 266 goto drop; 267 268 default: 269 /* Allow selective forwarding for most other protocols */ 270 fwd_mask |= p->br->group_fwd_mask; 271 if (fwd_mask & (1u << dest[5])) 272 goto forward; 273 } 274 275 /* Deliver packet to local host only */ 276 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, 277 NULL, br_handle_local_finish)) { 278 return RX_HANDLER_CONSUMED; /* consumed by filter */ 279 } else { 280 *pskb = skb; 281 return RX_HANDLER_PASS; /* continue processing */ 282 } 283 } 284 285 forward: 286 switch (p->state) { 287 case BR_STATE_FORWARDING: 288 rhook = rcu_dereference(br_should_route_hook); 289 if (rhook) { 290 if ((*rhook)(skb)) { 291 *pskb = skb; 292 return RX_HANDLER_PASS; 293 } 294 dest = eth_hdr(skb)->h_dest; 295 } 296 /* fall through */ 297 case BR_STATE_LEARNING: 298 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 299 skb->pkt_type = PACKET_HOST; 300 301 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, 302 br_handle_frame_finish); 303 break; 304 default: 305 drop: 306 kfree_skb(skb); 307 } 308 return RX_HANDLER_CONSUMED; 309 } 310