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 u16 vid = 0; 69 70 if (!p || p->state == BR_STATE_DISABLED) 71 goto drop; 72 73 if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb, &vid)) 74 goto drop; 75 76 /* insert into forwarding database after filtering to avoid spoofing */ 77 br = p->br; 78 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid); 79 80 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) && 81 br_multicast_rcv(br, p, skb)) 82 goto drop; 83 84 if (p->state == BR_STATE_LEARNING) 85 goto drop; 86 87 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 88 89 /* The packet skb2 goes to the local host (NULL to skip). */ 90 skb2 = NULL; 91 92 if (br->dev->flags & IFF_PROMISC) 93 skb2 = skb; 94 95 dst = NULL; 96 97 if (is_broadcast_ether_addr(dest)) 98 skb2 = skb; 99 else if (is_multicast_ether_addr(dest)) { 100 mdst = br_mdb_get(br, skb); 101 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) { 102 if ((mdst && mdst->mglist) || 103 br_multicast_is_router(br)) 104 skb2 = skb; 105 br_multicast_forward(mdst, skb, skb2); 106 skb = NULL; 107 if (!skb2) 108 goto out; 109 } else 110 skb2 = skb; 111 112 br->dev->stats.multicast++; 113 } else if ((dst = __br_fdb_get(br, dest, vid)) && 114 dst->is_local) { 115 skb2 = skb; 116 /* Do not forward the packet since it's local. */ 117 skb = NULL; 118 } 119 120 if (skb) { 121 if (dst) { 122 dst->used = jiffies; 123 br_forward(dst->dst, skb, skb2); 124 } else 125 br_flood_forward(br, skb, skb2); 126 } 127 128 if (skb2) 129 return br_pass_frame_up(skb2); 130 131 out: 132 return 0; 133 drop: 134 kfree_skb(skb); 135 goto out; 136 } 137 138 /* note: already called with rcu_read_lock */ 139 static int br_handle_local_finish(struct sk_buff *skb) 140 { 141 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 142 u16 vid = 0; 143 144 br_vlan_get_tag(skb, &vid); 145 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid); 146 return 0; /* process further */ 147 } 148 149 /* 150 * Return NULL if skb is handled 151 * note: already called with rcu_read_lock 152 */ 153 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 154 { 155 struct net_bridge_port *p; 156 struct sk_buff *skb = *pskb; 157 const unsigned char *dest = eth_hdr(skb)->h_dest; 158 br_should_route_hook_t *rhook; 159 160 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 161 return RX_HANDLER_PASS; 162 163 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 164 goto drop; 165 166 skb = skb_share_check(skb, GFP_ATOMIC); 167 if (!skb) 168 return RX_HANDLER_CONSUMED; 169 170 p = br_port_get_rcu(skb->dev); 171 172 if (unlikely(is_link_local_ether_addr(dest))) { 173 /* 174 * See IEEE 802.1D Table 7-10 Reserved addresses 175 * 176 * Assignment Value 177 * Bridge Group Address 01-80-C2-00-00-00 178 * (MAC Control) 802.3 01-80-C2-00-00-01 179 * (Link Aggregation) 802.3 01-80-C2-00-00-02 180 * 802.1X PAE address 01-80-C2-00-00-03 181 * 182 * 802.1AB LLDP 01-80-C2-00-00-0E 183 * 184 * Others reserved for future standardization 185 */ 186 switch (dest[5]) { 187 case 0x00: /* Bridge Group Address */ 188 /* If STP is turned off, 189 then must forward to keep loop detection */ 190 if (p->br->stp_enabled == BR_NO_STP) 191 goto forward; 192 break; 193 194 case 0x01: /* IEEE MAC (Pause) */ 195 goto drop; 196 197 default: 198 /* Allow selective forwarding for most other protocols */ 199 if (p->br->group_fwd_mask & (1u << dest[5])) 200 goto forward; 201 } 202 203 /* Deliver packet to local host only */ 204 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, 205 NULL, br_handle_local_finish)) { 206 return RX_HANDLER_CONSUMED; /* consumed by filter */ 207 } else { 208 *pskb = skb; 209 return RX_HANDLER_PASS; /* continue processing */ 210 } 211 } 212 213 forward: 214 switch (p->state) { 215 case BR_STATE_FORWARDING: 216 rhook = rcu_dereference(br_should_route_hook); 217 if (rhook) { 218 if ((*rhook)(skb)) { 219 *pskb = skb; 220 return RX_HANDLER_PASS; 221 } 222 dest = eth_hdr(skb)->h_dest; 223 } 224 /* fall through */ 225 case BR_STATE_LEARNING: 226 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 227 skb->pkt_type = PACKET_HOST; 228 229 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, 230 br_handle_frame_finish); 231 break; 232 default: 233 drop: 234 kfree_skb(skb); 235 } 236 return RX_HANDLER_CONSUMED; 237 } 238