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 64 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 65 dev_net(indev), NULL, skb, indev, NULL, 66 br_netif_receive_skb); 67 } 68 69 static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br, 70 u16 vid, struct net_bridge_port *p) 71 { 72 struct net_device *dev = br->dev; 73 struct neighbour *n; 74 struct arphdr *parp; 75 u8 *arpptr, *sha; 76 __be32 sip, tip; 77 78 BR_INPUT_SKB_CB(skb)->proxyarp_replied = false; 79 80 if (dev->flags & IFF_NOARP) 81 return; 82 83 if (!pskb_may_pull(skb, arp_hdr_len(dev))) { 84 dev->stats.tx_dropped++; 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 const unsigned char *dest = eth_hdr(skb)->h_dest; 132 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 133 struct net_bridge *br; 134 struct net_bridge_fdb_entry *dst; 135 struct net_bridge_mdb_entry *mdst; 136 struct sk_buff *skb2; 137 bool unicast = true; 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 /* insert into forwarding database after filtering to avoid spoofing */ 147 br = p->br; 148 if (p->flags & BR_LEARNING) 149 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false); 150 151 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) && 152 br_multicast_rcv(br, p, skb, vid)) 153 goto drop; 154 155 if (p->state == BR_STATE_LEARNING) 156 goto drop; 157 158 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 159 160 /* The packet skb2 goes to the local host (NULL to skip). */ 161 skb2 = NULL; 162 163 if (br->dev->flags & IFF_PROMISC) 164 skb2 = skb; 165 166 dst = NULL; 167 168 if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP)) 169 br_do_proxy_arp(skb, br, vid, p); 170 171 if (is_broadcast_ether_addr(dest)) { 172 skb2 = skb; 173 unicast = false; 174 } else if (is_multicast_ether_addr(dest)) { 175 mdst = br_mdb_get(br, skb, vid); 176 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 177 br_multicast_querier_exists(br, eth_hdr(skb))) { 178 if ((mdst && mdst->mglist) || 179 br_multicast_is_router(br)) 180 skb2 = skb; 181 br_multicast_forward(mdst, skb, skb2); 182 skb = NULL; 183 if (!skb2) 184 goto out; 185 } else 186 skb2 = skb; 187 188 unicast = false; 189 br->dev->stats.multicast++; 190 } else if ((dst = __br_fdb_get(br, dest, vid)) && 191 dst->is_local) { 192 skb2 = skb; 193 /* Do not forward the packet since it's local. */ 194 skb = NULL; 195 } 196 197 if (skb) { 198 if (dst) { 199 dst->used = jiffies; 200 br_forward(dst->dst, skb, skb2); 201 } else 202 br_flood_forward(br, skb, skb2, unicast); 203 } 204 205 if (skb2) 206 return br_pass_frame_up(skb2); 207 208 out: 209 return 0; 210 drop: 211 kfree_skb(skb); 212 goto out; 213 } 214 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 215 216 /* note: already called with rcu_read_lock */ 217 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 218 { 219 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 220 u16 vid = 0; 221 222 /* check if vlan is allowed, to avoid spoofing */ 223 if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid)) 224 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); 225 return 0; /* process further */ 226 } 227 228 /* 229 * Return NULL if skb is handled 230 * note: already called with rcu_read_lock 231 */ 232 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 233 { 234 struct net_bridge_port *p; 235 struct sk_buff *skb = *pskb; 236 const unsigned char *dest = eth_hdr(skb)->h_dest; 237 br_should_route_hook_t *rhook; 238 239 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 240 return RX_HANDLER_PASS; 241 242 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 243 goto drop; 244 245 skb = skb_share_check(skb, GFP_ATOMIC); 246 if (!skb) 247 return RX_HANDLER_CONSUMED; 248 249 p = br_port_get_rcu(skb->dev); 250 251 if (unlikely(is_link_local_ether_addr(dest))) { 252 u16 fwd_mask = p->br->group_fwd_mask_required; 253 254 /* 255 * See IEEE 802.1D Table 7-10 Reserved addresses 256 * 257 * Assignment Value 258 * Bridge Group Address 01-80-C2-00-00-00 259 * (MAC Control) 802.3 01-80-C2-00-00-01 260 * (Link Aggregation) 802.3 01-80-C2-00-00-02 261 * 802.1X PAE address 01-80-C2-00-00-03 262 * 263 * 802.1AB LLDP 01-80-C2-00-00-0E 264 * 265 * Others reserved for future standardization 266 */ 267 switch (dest[5]) { 268 case 0x00: /* Bridge Group Address */ 269 /* If STP is turned off, 270 then must forward to keep loop detection */ 271 if (p->br->stp_enabled == BR_NO_STP || 272 fwd_mask & (1u << dest[5])) 273 goto forward; 274 break; 275 276 case 0x01: /* IEEE MAC (Pause) */ 277 goto drop; 278 279 default: 280 /* Allow selective forwarding for most other protocols */ 281 fwd_mask |= p->br->group_fwd_mask; 282 if (fwd_mask & (1u << dest[5])) 283 goto forward; 284 } 285 286 /* Deliver packet to local host only */ 287 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 288 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 289 br_handle_local_finish)) { 290 return RX_HANDLER_CONSUMED; /* consumed by filter */ 291 } else { 292 *pskb = skb; 293 return RX_HANDLER_PASS; /* continue processing */ 294 } 295 } 296 297 forward: 298 switch (p->state) { 299 case BR_STATE_FORWARDING: 300 rhook = rcu_dereference(br_should_route_hook); 301 if (rhook) { 302 if ((*rhook)(skb)) { 303 *pskb = skb; 304 return RX_HANDLER_PASS; 305 } 306 dest = eth_hdr(skb)->h_dest; 307 } 308 /* fall through */ 309 case BR_STATE_LEARNING: 310 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 311 skb->pkt_type = PACKET_HOST; 312 313 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, 314 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 315 br_handle_frame_finish); 316 break; 317 default: 318 drop: 319 kfree_skb(skb); 320 } 321 return RX_HANDLER_CONSUMED; 322 } 323