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, NULL, skb, 59 indev, NULL, 60 netif_receive_skb_sk); 61 } 62 63 static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br, 64 u16 vid, struct net_bridge_port *p) 65 { 66 struct net_device *dev = br->dev; 67 struct neighbour *n; 68 struct arphdr *parp; 69 u8 *arpptr, *sha; 70 __be32 sip, tip; 71 72 BR_INPUT_SKB_CB(skb)->proxyarp_replied = false; 73 74 if (dev->flags & IFF_NOARP) 75 return; 76 77 if (!pskb_may_pull(skb, arp_hdr_len(dev))) { 78 dev->stats.tx_dropped++; 79 return; 80 } 81 parp = arp_hdr(skb); 82 83 if (parp->ar_pro != htons(ETH_P_IP) || 84 parp->ar_op != htons(ARPOP_REQUEST) || 85 parp->ar_hln != dev->addr_len || 86 parp->ar_pln != 4) 87 return; 88 89 arpptr = (u8 *)parp + sizeof(struct arphdr); 90 sha = arpptr; 91 arpptr += dev->addr_len; /* sha */ 92 memcpy(&sip, arpptr, sizeof(sip)); 93 arpptr += sizeof(sip); 94 arpptr += dev->addr_len; /* tha */ 95 memcpy(&tip, arpptr, sizeof(tip)); 96 97 if (ipv4_is_loopback(tip) || 98 ipv4_is_multicast(tip)) 99 return; 100 101 n = neigh_lookup(&arp_tbl, &tip, dev); 102 if (n) { 103 struct net_bridge_fdb_entry *f; 104 105 if (!(n->nud_state & NUD_VALID)) { 106 neigh_release(n); 107 return; 108 } 109 110 f = __br_fdb_get(br, n->ha, vid); 111 if (f && ((p->flags & BR_PROXYARP) || 112 (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) { 113 arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip, 114 sha, n->ha, sha); 115 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true; 116 } 117 118 neigh_release(n); 119 } 120 } 121 122 /* note: already called with rcu_read_lock */ 123 int br_handle_frame_finish(struct sock *sk, struct sk_buff *skb) 124 { 125 const unsigned char *dest = eth_hdr(skb)->h_dest; 126 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 127 struct net_bridge *br; 128 struct net_bridge_fdb_entry *dst; 129 struct net_bridge_mdb_entry *mdst; 130 struct sk_buff *skb2; 131 bool unicast = true; 132 u16 vid = 0; 133 134 if (!p || p->state == BR_STATE_DISABLED) 135 goto drop; 136 137 if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb, &vid)) 138 goto out; 139 140 /* insert into forwarding database after filtering to avoid spoofing */ 141 br = p->br; 142 if (p->flags & BR_LEARNING) 143 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false); 144 145 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) && 146 br_multicast_rcv(br, p, skb, vid)) 147 goto drop; 148 149 if (p->state == BR_STATE_LEARNING) 150 goto drop; 151 152 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 153 154 /* The packet skb2 goes to the local host (NULL to skip). */ 155 skb2 = NULL; 156 157 if (br->dev->flags & IFF_PROMISC) 158 skb2 = skb; 159 160 dst = NULL; 161 162 if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP)) 163 br_do_proxy_arp(skb, br, vid, p); 164 165 if (is_broadcast_ether_addr(dest)) { 166 skb2 = skb; 167 unicast = false; 168 } else if (is_multicast_ether_addr(dest)) { 169 mdst = br_mdb_get(br, skb, vid); 170 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 171 br_multicast_querier_exists(br, eth_hdr(skb))) { 172 if ((mdst && mdst->mglist) || 173 br_multicast_is_router(br)) 174 skb2 = skb; 175 br_multicast_forward(mdst, skb, skb2); 176 skb = NULL; 177 if (!skb2) 178 goto out; 179 } else 180 skb2 = skb; 181 182 unicast = false; 183 br->dev->stats.multicast++; 184 } else if ((dst = __br_fdb_get(br, dest, vid)) && 185 dst->is_local) { 186 skb2 = skb; 187 /* Do not forward the packet since it's local. */ 188 skb = NULL; 189 } 190 191 if (skb) { 192 if (dst) { 193 dst->used = jiffies; 194 br_forward(dst->dst, skb, skb2); 195 } else 196 br_flood_forward(br, skb, skb2, unicast); 197 } 198 199 if (skb2) 200 return br_pass_frame_up(skb2); 201 202 out: 203 return 0; 204 drop: 205 kfree_skb(skb); 206 goto out; 207 } 208 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 209 210 /* note: already called with rcu_read_lock */ 211 static int br_handle_local_finish(struct sock *sk, struct sk_buff *skb) 212 { 213 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 214 u16 vid = 0; 215 216 /* check if vlan is allowed, to avoid spoofing */ 217 if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid)) 218 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); 219 return 0; /* process further */ 220 } 221 222 /* 223 * Return NULL if skb is handled 224 * note: already called with rcu_read_lock 225 */ 226 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 227 { 228 struct net_bridge_port *p; 229 struct sk_buff *skb = *pskb; 230 const unsigned char *dest = eth_hdr(skb)->h_dest; 231 br_should_route_hook_t *rhook; 232 233 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 234 return RX_HANDLER_PASS; 235 236 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 237 goto drop; 238 239 skb = skb_share_check(skb, GFP_ATOMIC); 240 if (!skb) 241 return RX_HANDLER_CONSUMED; 242 243 p = br_port_get_rcu(skb->dev); 244 245 if (unlikely(is_link_local_ether_addr(dest))) { 246 u16 fwd_mask = p->br->group_fwd_mask_required; 247 248 /* 249 * See IEEE 802.1D Table 7-10 Reserved addresses 250 * 251 * Assignment Value 252 * Bridge Group Address 01-80-C2-00-00-00 253 * (MAC Control) 802.3 01-80-C2-00-00-01 254 * (Link Aggregation) 802.3 01-80-C2-00-00-02 255 * 802.1X PAE address 01-80-C2-00-00-03 256 * 257 * 802.1AB LLDP 01-80-C2-00-00-0E 258 * 259 * Others reserved for future standardization 260 */ 261 switch (dest[5]) { 262 case 0x00: /* Bridge Group Address */ 263 /* If STP is turned off, 264 then must forward to keep loop detection */ 265 if (p->br->stp_enabled == BR_NO_STP || 266 fwd_mask & (1u << dest[5])) 267 goto forward; 268 break; 269 270 case 0x01: /* IEEE MAC (Pause) */ 271 goto drop; 272 273 default: 274 /* Allow selective forwarding for most other protocols */ 275 fwd_mask |= p->br->group_fwd_mask; 276 if (fwd_mask & (1u << dest[5])) 277 goto forward; 278 } 279 280 /* Deliver packet to local host only */ 281 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, NULL, skb, 282 skb->dev, NULL, br_handle_local_finish)) { 283 return RX_HANDLER_CONSUMED; /* consumed by filter */ 284 } else { 285 *pskb = skb; 286 return RX_HANDLER_PASS; /* continue processing */ 287 } 288 } 289 290 forward: 291 switch (p->state) { 292 case BR_STATE_FORWARDING: 293 rhook = rcu_dereference(br_should_route_hook); 294 if (rhook) { 295 if ((*rhook)(skb)) { 296 *pskb = skb; 297 return RX_HANDLER_PASS; 298 } 299 dest = eth_hdr(skb)->h_dest; 300 } 301 /* fall through */ 302 case BR_STATE_LEARNING: 303 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 304 skb->pkt_type = PACKET_HOST; 305 306 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, NULL, skb, 307 skb->dev, NULL, 308 br_handle_frame_finish); 309 break; 310 default: 311 drop: 312 kfree_skb(skb); 313 } 314 return RX_HANDLER_CONSUMED; 315 } 316