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/export.h> 20 #include <linux/rculist.h> 21 #include "br_private.h" 22 23 /* Hook for brouter */ 24 br_should_route_hook_t __rcu *br_should_route_hook __read_mostly; 25 EXPORT_SYMBOL(br_should_route_hook); 26 27 static int br_pass_frame_up(struct sk_buff *skb) 28 { 29 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; 30 struct net_bridge *br = netdev_priv(brdev); 31 struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats); 32 33 u64_stats_update_begin(&brstats->syncp); 34 brstats->rx_packets++; 35 brstats->rx_bytes += skb->len; 36 u64_stats_update_end(&brstats->syncp); 37 38 /* Bridge is just like any other port. Make sure the 39 * packet is allowed except in promisc modue when someone 40 * may be running packet capture. 41 */ 42 if (!(brdev->flags & IFF_PROMISC) && 43 !br_allowed_egress(br, br_get_vlan_info(br), skb)) { 44 kfree_skb(skb); 45 return NET_RX_DROP; 46 } 47 48 skb = br_handle_vlan(br, br_get_vlan_info(br), skb); 49 if (!skb) 50 return NET_RX_DROP; 51 52 indev = skb->dev; 53 skb->dev = brdev; 54 55 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL, 56 netif_receive_skb); 57 } 58 59 /* note: already called with rcu_read_lock */ 60 int br_handle_frame_finish(struct sk_buff *skb) 61 { 62 const unsigned char *dest = eth_hdr(skb)->h_dest; 63 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 64 struct net_bridge *br; 65 struct net_bridge_fdb_entry *dst; 66 struct net_bridge_mdb_entry *mdst; 67 struct sk_buff *skb2; 68 bool unicast = true; 69 u16 vid = 0; 70 71 if (!p || p->state == BR_STATE_DISABLED) 72 goto drop; 73 74 if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb, &vid)) 75 goto drop; 76 77 /* insert into forwarding database after filtering to avoid spoofing */ 78 br = p->br; 79 if (p->flags & BR_LEARNING) 80 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid); 81 82 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) && 83 br_multicast_rcv(br, p, skb, vid)) 84 goto drop; 85 86 if (p->state == BR_STATE_LEARNING) 87 goto drop; 88 89 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 90 91 /* The packet skb2 goes to the local host (NULL to skip). */ 92 skb2 = NULL; 93 94 if (br->dev->flags & IFF_PROMISC) 95 skb2 = skb; 96 97 dst = NULL; 98 99 if (is_broadcast_ether_addr(dest)) { 100 skb2 = skb; 101 unicast = false; 102 } else if (is_multicast_ether_addr(dest)) { 103 mdst = br_mdb_get(br, skb, vid); 104 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 105 br_multicast_querier_exists(br, eth_hdr(skb))) { 106 if ((mdst && mdst->mglist) || 107 br_multicast_is_router(br)) 108 skb2 = skb; 109 br_multicast_forward(mdst, skb, skb2); 110 skb = NULL; 111 if (!skb2) 112 goto out; 113 } else 114 skb2 = skb; 115 116 unicast = false; 117 br->dev->stats.multicast++; 118 } else if ((dst = __br_fdb_get(br, dest, vid)) && 119 dst->is_local) { 120 skb2 = skb; 121 /* Do not forward the packet since it's local. */ 122 skb = NULL; 123 } 124 125 if (skb) { 126 if (dst) { 127 dst->used = jiffies; 128 br_forward(dst->dst, skb, skb2); 129 } else 130 br_flood_forward(br, skb, skb2, unicast); 131 } 132 133 if (skb2) 134 return br_pass_frame_up(skb2); 135 136 out: 137 return 0; 138 drop: 139 kfree_skb(skb); 140 goto out; 141 } 142 143 /* note: already called with rcu_read_lock */ 144 static int br_handle_local_finish(struct sk_buff *skb) 145 { 146 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 147 u16 vid = 0; 148 149 br_vlan_get_tag(skb, &vid); 150 if (p->flags & BR_LEARNING) 151 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid); 152 return 0; /* process further */ 153 } 154 155 /* 156 * Return NULL if skb is handled 157 * note: already called with rcu_read_lock 158 */ 159 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 160 { 161 struct net_bridge_port *p; 162 struct sk_buff *skb = *pskb; 163 const unsigned char *dest = eth_hdr(skb)->h_dest; 164 br_should_route_hook_t *rhook; 165 166 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 167 return RX_HANDLER_PASS; 168 169 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 170 goto drop; 171 172 skb = skb_share_check(skb, GFP_ATOMIC); 173 if (!skb) 174 return RX_HANDLER_CONSUMED; 175 176 p = br_port_get_rcu(skb->dev); 177 178 if (unlikely(is_link_local_ether_addr(dest))) { 179 /* 180 * See IEEE 802.1D Table 7-10 Reserved addresses 181 * 182 * Assignment Value 183 * Bridge Group Address 01-80-C2-00-00-00 184 * (MAC Control) 802.3 01-80-C2-00-00-01 185 * (Link Aggregation) 802.3 01-80-C2-00-00-02 186 * 802.1X PAE address 01-80-C2-00-00-03 187 * 188 * 802.1AB LLDP 01-80-C2-00-00-0E 189 * 190 * Others reserved for future standardization 191 */ 192 switch (dest[5]) { 193 case 0x00: /* Bridge Group Address */ 194 /* If STP is turned off, 195 then must forward to keep loop detection */ 196 if (p->br->stp_enabled == BR_NO_STP) 197 goto forward; 198 break; 199 200 case 0x01: /* IEEE MAC (Pause) */ 201 goto drop; 202 203 default: 204 /* Allow selective forwarding for most other protocols */ 205 if (p->br->group_fwd_mask & (1u << dest[5])) 206 goto forward; 207 } 208 209 /* Deliver packet to local host only */ 210 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, 211 NULL, br_handle_local_finish)) { 212 return RX_HANDLER_CONSUMED; /* consumed by filter */ 213 } else { 214 *pskb = skb; 215 return RX_HANDLER_PASS; /* continue processing */ 216 } 217 } 218 219 forward: 220 switch (p->state) { 221 case BR_STATE_FORWARDING: 222 rhook = rcu_dereference(br_should_route_hook); 223 if (rhook) { 224 if ((*rhook)(skb)) { 225 *pskb = skb; 226 return RX_HANDLER_PASS; 227 } 228 dest = eth_hdr(skb)->h_dest; 229 } 230 /* fall through */ 231 case BR_STATE_LEARNING: 232 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 233 skb->pkt_type = PACKET_HOST; 234 235 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, 236 br_handle_frame_finish); 237 break; 238 default: 239 drop: 240 kfree_skb(skb); 241 } 242 return RX_HANDLER_CONSUMED; 243 } 244