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)) 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 if ((mdst && mdst->mglist) || 106 br_multicast_is_router(br)) 107 skb2 = skb; 108 br_multicast_forward(mdst, skb, skb2); 109 skb = NULL; 110 if (!skb2) 111 goto out; 112 } else 113 skb2 = skb; 114 115 unicast = false; 116 br->dev->stats.multicast++; 117 } else if ((dst = __br_fdb_get(br, dest, vid)) && 118 dst->is_local) { 119 skb2 = skb; 120 /* Do not forward the packet since it's local. */ 121 skb = NULL; 122 } 123 124 if (skb) { 125 if (dst) { 126 dst->used = jiffies; 127 br_forward(dst->dst, skb, skb2); 128 } else 129 br_flood_forward(br, skb, skb2, unicast); 130 } 131 132 if (skb2) 133 return br_pass_frame_up(skb2); 134 135 out: 136 return 0; 137 drop: 138 kfree_skb(skb); 139 goto out; 140 } 141 142 /* note: already called with rcu_read_lock */ 143 static int br_handle_local_finish(struct sk_buff *skb) 144 { 145 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 146 u16 vid = 0; 147 148 br_vlan_get_tag(skb, &vid); 149 if (p->flags & BR_LEARNING) 150 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid); 151 return 0; /* process further */ 152 } 153 154 /* 155 * Return NULL if skb is handled 156 * note: already called with rcu_read_lock 157 */ 158 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 159 { 160 struct net_bridge_port *p; 161 struct sk_buff *skb = *pskb; 162 const unsigned char *dest = eth_hdr(skb)->h_dest; 163 br_should_route_hook_t *rhook; 164 165 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 166 return RX_HANDLER_PASS; 167 168 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 169 goto drop; 170 171 skb = skb_share_check(skb, GFP_ATOMIC); 172 if (!skb) 173 return RX_HANDLER_CONSUMED; 174 175 p = br_port_get_rcu(skb->dev); 176 177 if (unlikely(is_link_local_ether_addr(dest))) { 178 /* 179 * See IEEE 802.1D Table 7-10 Reserved addresses 180 * 181 * Assignment Value 182 * Bridge Group Address 01-80-C2-00-00-00 183 * (MAC Control) 802.3 01-80-C2-00-00-01 184 * (Link Aggregation) 802.3 01-80-C2-00-00-02 185 * 802.1X PAE address 01-80-C2-00-00-03 186 * 187 * 802.1AB LLDP 01-80-C2-00-00-0E 188 * 189 * Others reserved for future standardization 190 */ 191 switch (dest[5]) { 192 case 0x00: /* Bridge Group Address */ 193 /* If STP is turned off, 194 then must forward to keep loop detection */ 195 if (p->br->stp_enabled == BR_NO_STP) 196 goto forward; 197 break; 198 199 case 0x01: /* IEEE MAC (Pause) */ 200 goto drop; 201 202 default: 203 /* Allow selective forwarding for most other protocols */ 204 if (p->br->group_fwd_mask & (1u << dest[5])) 205 goto forward; 206 } 207 208 /* Deliver packet to local host only */ 209 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, 210 NULL, br_handle_local_finish)) { 211 return RX_HANDLER_CONSUMED; /* consumed by filter */ 212 } else { 213 *pskb = skb; 214 return RX_HANDLER_PASS; /* continue processing */ 215 } 216 } 217 218 forward: 219 switch (p->state) { 220 case BR_STATE_FORWARDING: 221 rhook = rcu_dereference(br_should_route_hook); 222 if (rhook) { 223 if ((*rhook)(skb)) { 224 *pskb = skb; 225 return RX_HANDLER_PASS; 226 } 227 dest = eth_hdr(skb)->h_dest; 228 } 229 /* fall through */ 230 case BR_STATE_LEARNING: 231 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 232 skb->pkt_type = PACKET_HOST; 233 234 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, 235 br_handle_frame_finish); 236 break; 237 default: 238 drop: 239 kfree_skb(skb); 240 } 241 return RX_HANDLER_CONSUMED; 242 } 243