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_netif_receive_skb(struct sock *sk, struct sk_buff *skb) 30 { 31 return netif_receive_skb(skb); 32 } 33 34 static int br_pass_frame_up(struct sk_buff *skb) 35 { 36 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; 37 struct net_bridge *br = netdev_priv(brdev); 38 struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats); 39 struct net_port_vlans *pv; 40 41 u64_stats_update_begin(&brstats->syncp); 42 brstats->rx_packets++; 43 brstats->rx_bytes += skb->len; 44 u64_stats_update_end(&brstats->syncp); 45 46 /* Bridge is just like any other port. Make sure the 47 * packet is allowed except in promisc modue when someone 48 * may be running packet capture. 49 */ 50 pv = br_get_vlan_info(br); 51 if (!(brdev->flags & IFF_PROMISC) && 52 !br_allowed_egress(br, pv, skb)) { 53 kfree_skb(skb); 54 return NET_RX_DROP; 55 } 56 57 indev = skb->dev; 58 skb->dev = brdev; 59 skb = br_handle_vlan(br, pv, skb); 60 if (!skb) 61 return NET_RX_DROP; 62 63 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 64 dev_net(indev), NULL, skb, indev, NULL, 65 br_netif_receive_skb); 66 } 67 68 static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br, 69 u16 vid, struct net_bridge_port *p) 70 { 71 struct net_device *dev = br->dev; 72 struct neighbour *n; 73 struct arphdr *parp; 74 u8 *arpptr, *sha; 75 __be32 sip, tip; 76 77 BR_INPUT_SKB_CB(skb)->proxyarp_replied = false; 78 79 if (dev->flags & IFF_NOARP) 80 return; 81 82 if (!pskb_may_pull(skb, arp_hdr_len(dev))) { 83 dev->stats.tx_dropped++; 84 return; 85 } 86 parp = arp_hdr(skb); 87 88 if (parp->ar_pro != htons(ETH_P_IP) || 89 parp->ar_op != htons(ARPOP_REQUEST) || 90 parp->ar_hln != dev->addr_len || 91 parp->ar_pln != 4) 92 return; 93 94 arpptr = (u8 *)parp + sizeof(struct arphdr); 95 sha = arpptr; 96 arpptr += dev->addr_len; /* sha */ 97 memcpy(&sip, arpptr, sizeof(sip)); 98 arpptr += sizeof(sip); 99 arpptr += dev->addr_len; /* tha */ 100 memcpy(&tip, arpptr, sizeof(tip)); 101 102 if (ipv4_is_loopback(tip) || 103 ipv4_is_multicast(tip)) 104 return; 105 106 n = neigh_lookup(&arp_tbl, &tip, dev); 107 if (n) { 108 struct net_bridge_fdb_entry *f; 109 110 if (!(n->nud_state & NUD_VALID)) { 111 neigh_release(n); 112 return; 113 } 114 115 f = __br_fdb_get(br, n->ha, vid); 116 if (f && ((p->flags & BR_PROXYARP) || 117 (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) { 118 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip, 119 sha, n->ha, sha); 120 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true; 121 } 122 123 neigh_release(n); 124 } 125 } 126 127 /* note: already called with rcu_read_lock */ 128 int br_handle_frame_finish(struct sock *sk, struct sk_buff *skb) 129 { 130 const unsigned char *dest = eth_hdr(skb)->h_dest; 131 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 132 struct net_bridge *br; 133 struct net_bridge_fdb_entry *dst; 134 struct net_bridge_mdb_entry *mdst; 135 struct sk_buff *skb2; 136 bool unicast = true; 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_get_vlan_info(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 /* The packet skb2 goes to the local host (NULL to skip). */ 160 skb2 = NULL; 161 162 if (br->dev->flags & IFF_PROMISC) 163 skb2 = skb; 164 165 dst = NULL; 166 167 if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP)) 168 br_do_proxy_arp(skb, br, vid, p); 169 170 if (is_broadcast_ether_addr(dest)) { 171 skb2 = skb; 172 unicast = false; 173 } else if (is_multicast_ether_addr(dest)) { 174 mdst = br_mdb_get(br, skb, vid); 175 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 176 br_multicast_querier_exists(br, eth_hdr(skb))) { 177 if ((mdst && mdst->mglist) || 178 br_multicast_is_router(br)) 179 skb2 = skb; 180 br_multicast_forward(mdst, skb, skb2); 181 skb = NULL; 182 if (!skb2) 183 goto out; 184 } else 185 skb2 = skb; 186 187 unicast = false; 188 br->dev->stats.multicast++; 189 } else if ((dst = __br_fdb_get(br, dest, vid)) && 190 dst->is_local) { 191 skb2 = skb; 192 /* Do not forward the packet since it's local. */ 193 skb = NULL; 194 } 195 196 if (skb) { 197 if (dst) { 198 dst->used = jiffies; 199 br_forward(dst->dst, skb, skb2); 200 } else 201 br_flood_forward(br, skb, skb2, unicast); 202 } 203 204 if (skb2) 205 return br_pass_frame_up(skb2); 206 207 out: 208 return 0; 209 drop: 210 kfree_skb(skb); 211 goto out; 212 } 213 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 214 215 /* note: already called with rcu_read_lock */ 216 static int br_handle_local_finish(struct sock *sk, struct sk_buff *skb) 217 { 218 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 219 u16 vid = 0; 220 221 /* check if vlan is allowed, to avoid spoofing */ 222 if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid)) 223 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); 224 return 0; /* process further */ 225 } 226 227 /* 228 * Return NULL if skb is handled 229 * note: already called with rcu_read_lock 230 */ 231 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 232 { 233 struct net_bridge_port *p; 234 struct sk_buff *skb = *pskb; 235 const unsigned char *dest = eth_hdr(skb)->h_dest; 236 br_should_route_hook_t *rhook; 237 238 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 239 return RX_HANDLER_PASS; 240 241 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 242 goto drop; 243 244 skb = skb_share_check(skb, GFP_ATOMIC); 245 if (!skb) 246 return RX_HANDLER_CONSUMED; 247 248 p = br_port_get_rcu(skb->dev); 249 250 if (unlikely(is_link_local_ether_addr(dest))) { 251 u16 fwd_mask = p->br->group_fwd_mask_required; 252 253 /* 254 * See IEEE 802.1D Table 7-10 Reserved addresses 255 * 256 * Assignment Value 257 * Bridge Group Address 01-80-C2-00-00-00 258 * (MAC Control) 802.3 01-80-C2-00-00-01 259 * (Link Aggregation) 802.3 01-80-C2-00-00-02 260 * 802.1X PAE address 01-80-C2-00-00-03 261 * 262 * 802.1AB LLDP 01-80-C2-00-00-0E 263 * 264 * Others reserved for future standardization 265 */ 266 switch (dest[5]) { 267 case 0x00: /* Bridge Group Address */ 268 /* If STP is turned off, 269 then must forward to keep loop detection */ 270 if (p->br->stp_enabled == BR_NO_STP || 271 fwd_mask & (1u << dest[5])) 272 goto forward; 273 break; 274 275 case 0x01: /* IEEE MAC (Pause) */ 276 goto drop; 277 278 default: 279 /* Allow selective forwarding for most other protocols */ 280 fwd_mask |= p->br->group_fwd_mask; 281 if (fwd_mask & (1u << dest[5])) 282 goto forward; 283 } 284 285 /* Deliver packet to local host only */ 286 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 287 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 288 br_handle_local_finish)) { 289 return RX_HANDLER_CONSUMED; /* consumed by filter */ 290 } else { 291 *pskb = skb; 292 return RX_HANDLER_PASS; /* continue processing */ 293 } 294 } 295 296 forward: 297 switch (p->state) { 298 case BR_STATE_FORWARDING: 299 rhook = rcu_dereference(br_should_route_hook); 300 if (rhook) { 301 if ((*rhook)(skb)) { 302 *pskb = skb; 303 return RX_HANDLER_PASS; 304 } 305 dest = eth_hdr(skb)->h_dest; 306 } 307 /* fall through */ 308 case BR_STATE_LEARNING: 309 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 310 skb->pkt_type = PACKET_HOST; 311 312 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, 313 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 314 br_handle_frame_finish); 315 break; 316 default: 317 drop: 318 kfree_skb(skb); 319 } 320 return RX_HANDLER_CONSUMED; 321 } 322