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, struct net_bridge_port *p) 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 BR_INPUT_SKB_CB(skb)->proxyarp_replied = false; 72 73 if (dev->flags & IFF_NOARP) 74 return; 75 76 if (!pskb_may_pull(skb, arp_hdr_len(dev))) { 77 dev->stats.tx_dropped++; 78 return; 79 } 80 parp = arp_hdr(skb); 81 82 if (parp->ar_pro != htons(ETH_P_IP) || 83 parp->ar_op != htons(ARPOP_REQUEST) || 84 parp->ar_hln != dev->addr_len || 85 parp->ar_pln != 4) 86 return; 87 88 arpptr = (u8 *)parp + sizeof(struct arphdr); 89 sha = arpptr; 90 arpptr += dev->addr_len; /* sha */ 91 memcpy(&sip, arpptr, sizeof(sip)); 92 arpptr += sizeof(sip); 93 arpptr += dev->addr_len; /* tha */ 94 memcpy(&tip, arpptr, sizeof(tip)); 95 96 if (ipv4_is_loopback(tip) || 97 ipv4_is_multicast(tip)) 98 return; 99 100 n = neigh_lookup(&arp_tbl, &tip, dev); 101 if (n) { 102 struct net_bridge_fdb_entry *f; 103 104 if (!(n->nud_state & NUD_VALID)) { 105 neigh_release(n); 106 return; 107 } 108 109 f = __br_fdb_get(br, n->ha, vid); 110 if (f && ((p->flags & BR_PROXYARP) || 111 (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) { 112 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip, 113 sha, n->ha, sha); 114 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true; 115 } 116 117 neigh_release(n); 118 } 119 } 120 121 /* note: already called with rcu_read_lock */ 122 int br_handle_frame_finish(struct sk_buff *skb) 123 { 124 const unsigned char *dest = eth_hdr(skb)->h_dest; 125 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 126 struct net_bridge *br; 127 struct net_bridge_fdb_entry *dst; 128 struct net_bridge_mdb_entry *mdst; 129 struct sk_buff *skb2; 130 bool unicast = true; 131 u16 vid = 0; 132 133 if (!p || p->state == BR_STATE_DISABLED) 134 goto drop; 135 136 if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb, &vid)) 137 goto out; 138 139 /* insert into forwarding database after filtering to avoid spoofing */ 140 br = p->br; 141 if (p->flags & BR_LEARNING) 142 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false); 143 144 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) && 145 br_multicast_rcv(br, p, skb, vid)) 146 goto drop; 147 148 if (p->state == BR_STATE_LEARNING) 149 goto drop; 150 151 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 152 153 /* The packet skb2 goes to the local host (NULL to skip). */ 154 skb2 = NULL; 155 156 if (br->dev->flags & IFF_PROMISC) 157 skb2 = skb; 158 159 dst = NULL; 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 skb2 = skb; 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 skb2 = skb; 174 br_multicast_forward(mdst, skb, skb2); 175 skb = NULL; 176 if (!skb2) 177 goto out; 178 } else 179 skb2 = skb; 180 181 unicast = false; 182 br->dev->stats.multicast++; 183 } else if ((dst = __br_fdb_get(br, dest, vid)) && 184 dst->is_local) { 185 skb2 = skb; 186 /* Do not forward the packet since it's local. */ 187 skb = NULL; 188 } 189 190 if (skb) { 191 if (dst) { 192 dst->used = jiffies; 193 br_forward(dst->dst, skb, skb2); 194 } else 195 br_flood_forward(br, skb, skb2, unicast); 196 } 197 198 if (skb2) 199 return br_pass_frame_up(skb2); 200 201 out: 202 return 0; 203 drop: 204 kfree_skb(skb); 205 goto out; 206 } 207 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 208 209 /* note: already called with rcu_read_lock */ 210 static int br_handle_local_finish(struct sk_buff *skb) 211 { 212 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 213 u16 vid = 0; 214 215 /* check if vlan is allowed, to avoid spoofing */ 216 if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid)) 217 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); 218 return 0; /* process further */ 219 } 220 221 /* 222 * Return NULL if skb is handled 223 * note: already called with rcu_read_lock 224 */ 225 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 226 { 227 struct net_bridge_port *p; 228 struct sk_buff *skb = *pskb; 229 const unsigned char *dest = eth_hdr(skb)->h_dest; 230 br_should_route_hook_t *rhook; 231 232 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 233 return RX_HANDLER_PASS; 234 235 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 236 goto drop; 237 238 skb = skb_share_check(skb, GFP_ATOMIC); 239 if (!skb) 240 return RX_HANDLER_CONSUMED; 241 242 p = br_port_get_rcu(skb->dev); 243 244 if (unlikely(is_link_local_ether_addr(dest))) { 245 u16 fwd_mask = p->br->group_fwd_mask_required; 246 247 /* 248 * See IEEE 802.1D Table 7-10 Reserved addresses 249 * 250 * Assignment Value 251 * Bridge Group Address 01-80-C2-00-00-00 252 * (MAC Control) 802.3 01-80-C2-00-00-01 253 * (Link Aggregation) 802.3 01-80-C2-00-00-02 254 * 802.1X PAE address 01-80-C2-00-00-03 255 * 256 * 802.1AB LLDP 01-80-C2-00-00-0E 257 * 258 * Others reserved for future standardization 259 */ 260 switch (dest[5]) { 261 case 0x00: /* Bridge Group Address */ 262 /* If STP is turned off, 263 then must forward to keep loop detection */ 264 if (p->br->stp_enabled == BR_NO_STP || 265 fwd_mask & (1u << dest[5])) 266 goto forward; 267 break; 268 269 case 0x01: /* IEEE MAC (Pause) */ 270 goto drop; 271 272 default: 273 /* Allow selective forwarding for most other protocols */ 274 fwd_mask |= p->br->group_fwd_mask; 275 if (fwd_mask & (1u << dest[5])) 276 goto forward; 277 } 278 279 /* Deliver packet to local host only */ 280 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, 281 NULL, br_handle_local_finish)) { 282 return RX_HANDLER_CONSUMED; /* consumed by filter */ 283 } else { 284 *pskb = skb; 285 return RX_HANDLER_PASS; /* continue processing */ 286 } 287 } 288 289 forward: 290 switch (p->state) { 291 case BR_STATE_FORWARDING: 292 rhook = rcu_dereference(br_should_route_hook); 293 if (rhook) { 294 if ((*rhook)(skb)) { 295 *pskb = skb; 296 return RX_HANDLER_PASS; 297 } 298 dest = eth_hdr(skb)->h_dest; 299 } 300 /* fall through */ 301 case BR_STATE_LEARNING: 302 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 303 skb->pkt_type = PACKET_HOST; 304 305 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, 306 br_handle_frame_finish); 307 break; 308 default: 309 drop: 310 kfree_skb(skb); 311 } 312 return RX_HANDLER_CONSUMED; 313 } 314