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 #include "br_private_tunnel.h" 25 26 /* Hook for brouter */ 27 br_should_route_hook_t __rcu *br_should_route_hook __read_mostly; 28 EXPORT_SYMBOL(br_should_route_hook); 29 30 static int 31 br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb) 32 { 33 br_drop_fake_rtable(skb); 34 return netif_receive_skb(skb); 35 } 36 37 static int br_pass_frame_up(struct sk_buff *skb) 38 { 39 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; 40 struct net_bridge *br = netdev_priv(brdev); 41 struct net_bridge_vlan_group *vg; 42 struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats); 43 44 u64_stats_update_begin(&brstats->syncp); 45 brstats->rx_packets++; 46 brstats->rx_bytes += skb->len; 47 u64_stats_update_end(&brstats->syncp); 48 49 vg = br_vlan_group_rcu(br); 50 /* Bridge is just like any other port. Make sure the 51 * packet is allowed except in promisc modue when someone 52 * may be running packet capture. 53 */ 54 if (!(brdev->flags & IFF_PROMISC) && 55 !br_allowed_egress(vg, skb)) { 56 kfree_skb(skb); 57 return NET_RX_DROP; 58 } 59 60 indev = skb->dev; 61 skb->dev = brdev; 62 skb = br_handle_vlan(br, NULL, vg, skb); 63 if (!skb) 64 return NET_RX_DROP; 65 /* update the multicast stats if the packet is IGMP/MLD */ 66 br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb), 67 BR_MCAST_DIR_TX); 68 69 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, 70 dev_net(indev), NULL, skb, indev, NULL, 71 br_netif_receive_skb); 72 } 73 74 /* note: already called with rcu_read_lock */ 75 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 76 { 77 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 78 enum br_pkt_type pkt_type = BR_PKT_UNICAST; 79 struct net_bridge_fdb_entry *dst = NULL; 80 struct net_bridge_mdb_entry *mdst; 81 bool local_rcv, mcast_hit = false; 82 const unsigned char *dest; 83 struct net_bridge *br; 84 u16 vid = 0; 85 86 if (!p || p->state == BR_STATE_DISABLED) 87 goto drop; 88 89 if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid)) 90 goto out; 91 92 nbp_switchdev_frame_mark(p, skb); 93 94 /* insert into forwarding database after filtering to avoid spoofing */ 95 br = p->br; 96 if (p->flags & BR_LEARNING) 97 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false); 98 99 local_rcv = !!(br->dev->flags & IFF_PROMISC); 100 dest = eth_hdr(skb)->h_dest; 101 if (is_multicast_ether_addr(dest)) { 102 /* by definition the broadcast is also a multicast address */ 103 if (is_broadcast_ether_addr(dest)) { 104 pkt_type = BR_PKT_BROADCAST; 105 local_rcv = true; 106 } else { 107 pkt_type = BR_PKT_MULTICAST; 108 if (br_multicast_rcv(br, p, skb, vid)) 109 goto drop; 110 } 111 } 112 113 if (p->state == BR_STATE_LEARNING) 114 goto drop; 115 116 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 117 BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED); 118 119 if (IS_ENABLED(CONFIG_INET) && 120 (skb->protocol == htons(ETH_P_ARP) || 121 skb->protocol == htons(ETH_P_RARP))) { 122 br_do_proxy_suppress_arp(skb, br, vid, p); 123 } else if (IS_ENABLED(CONFIG_IPV6) && 124 skb->protocol == htons(ETH_P_IPV6) && 125 br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) && 126 pskb_may_pull(skb, sizeof(struct ipv6hdr) + 127 sizeof(struct nd_msg)) && 128 ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) { 129 struct nd_msg *msg, _msg; 130 131 msg = br_is_nd_neigh_msg(skb, &_msg); 132 if (msg) 133 br_do_suppress_nd(skb, br, vid, p, msg); 134 } 135 136 switch (pkt_type) { 137 case BR_PKT_MULTICAST: 138 mdst = br_mdb_get(br, skb, vid); 139 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 140 br_multicast_querier_exists(br, eth_hdr(skb))) { 141 if ((mdst && mdst->host_joined) || 142 br_multicast_is_router(br)) { 143 local_rcv = true; 144 br->dev->stats.multicast++; 145 } 146 mcast_hit = true; 147 } else { 148 local_rcv = true; 149 br->dev->stats.multicast++; 150 } 151 break; 152 case BR_PKT_UNICAST: 153 dst = br_fdb_find_rcu(br, dest, vid); 154 default: 155 break; 156 } 157 158 if (dst) { 159 unsigned long now = jiffies; 160 161 if (dst->is_local) 162 return br_pass_frame_up(skb); 163 164 if (now != dst->used) 165 dst->used = now; 166 br_forward(dst->dst, skb, local_rcv, false); 167 } else { 168 if (!mcast_hit) 169 br_flood(br, skb, pkt_type, local_rcv, false); 170 else 171 br_multicast_flood(mdst, skb, local_rcv, false); 172 } 173 174 if (local_rcv) 175 return br_pass_frame_up(skb); 176 177 out: 178 return 0; 179 drop: 180 kfree_skb(skb); 181 goto out; 182 } 183 EXPORT_SYMBOL_GPL(br_handle_frame_finish); 184 185 static void __br_handle_local_finish(struct sk_buff *skb) 186 { 187 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 188 u16 vid = 0; 189 190 /* check if vlan is allowed, to avoid spoofing */ 191 if ((p->flags & BR_LEARNING) && 192 !br_opt_get(p->br, BROPT_NO_LL_LEARN) && 193 br_should_learn(p, skb, &vid)) 194 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); 195 } 196 197 /* note: already called with rcu_read_lock */ 198 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 199 { 200 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 201 202 __br_handle_local_finish(skb); 203 204 BR_INPUT_SKB_CB(skb)->brdev = p->br->dev; 205 br_pass_frame_up(skb); 206 return 0; 207 } 208 209 /* 210 * Return NULL if skb is handled 211 * note: already called with rcu_read_lock 212 */ 213 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 214 { 215 struct net_bridge_port *p; 216 struct sk_buff *skb = *pskb; 217 const unsigned char *dest = eth_hdr(skb)->h_dest; 218 br_should_route_hook_t *rhook; 219 220 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 221 return RX_HANDLER_PASS; 222 223 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 224 goto drop; 225 226 skb = skb_share_check(skb, GFP_ATOMIC); 227 if (!skb) 228 return RX_HANDLER_CONSUMED; 229 230 p = br_port_get_rcu(skb->dev); 231 if (p->flags & BR_VLAN_TUNNEL) { 232 if (br_handle_ingress_vlan_tunnel(skb, p, 233 nbp_vlan_group_rcu(p))) 234 goto drop; 235 } 236 237 if (unlikely(is_link_local_ether_addr(dest))) { 238 u16 fwd_mask = p->br->group_fwd_mask_required; 239 240 /* 241 * See IEEE 802.1D Table 7-10 Reserved addresses 242 * 243 * Assignment Value 244 * Bridge Group Address 01-80-C2-00-00-00 245 * (MAC Control) 802.3 01-80-C2-00-00-01 246 * (Link Aggregation) 802.3 01-80-C2-00-00-02 247 * 802.1X PAE address 01-80-C2-00-00-03 248 * 249 * 802.1AB LLDP 01-80-C2-00-00-0E 250 * 251 * Others reserved for future standardization 252 */ 253 fwd_mask |= p->group_fwd_mask; 254 switch (dest[5]) { 255 case 0x00: /* Bridge Group Address */ 256 /* If STP is turned off, 257 then must forward to keep loop detection */ 258 if (p->br->stp_enabled == BR_NO_STP || 259 fwd_mask & (1u << dest[5])) 260 goto forward; 261 *pskb = skb; 262 __br_handle_local_finish(skb); 263 return RX_HANDLER_PASS; 264 265 case 0x01: /* IEEE MAC (Pause) */ 266 goto drop; 267 268 case 0x0E: /* 802.1AB LLDP */ 269 fwd_mask |= p->br->group_fwd_mask; 270 if (fwd_mask & (1u << dest[5])) 271 goto forward; 272 *pskb = skb; 273 __br_handle_local_finish(skb); 274 return RX_HANDLER_PASS; 275 276 default: 277 /* Allow selective forwarding for most other protocols */ 278 fwd_mask |= p->br->group_fwd_mask; 279 if (fwd_mask & (1u << dest[5])) 280 goto forward; 281 } 282 283 /* Deliver packet to local host only */ 284 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev), 285 NULL, skb, skb->dev, NULL, br_handle_local_finish); 286 return RX_HANDLER_CONSUMED; 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, 306 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 307 br_handle_frame_finish); 308 break; 309 default: 310 drop: 311 kfree_skb(skb); 312 } 313 return RX_HANDLER_CONSUMED; 314 } 315