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 pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats); 32 struct net_port_vlans *pv; 33 34 u64_stats_update_begin(&brstats->syncp); 35 brstats->rx_packets++; 36 brstats->rx_bytes += skb->len; 37 u64_stats_update_end(&brstats->syncp); 38 39 /* Bridge is just like any other port. Make sure the 40 * packet is allowed except in promisc modue when someone 41 * may be running packet capture. 42 */ 43 pv = br_get_vlan_info(br); 44 if (!(brdev->flags & IFF_PROMISC) && 45 !br_allowed_egress(br, pv, skb)) { 46 kfree_skb(skb); 47 return NET_RX_DROP; 48 } 49 50 indev = skb->dev; 51 skb->dev = brdev; 52 skb = br_handle_vlan(br, pv, skb); 53 if (!skb) 54 return NET_RX_DROP; 55 56 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL, 57 netif_receive_skb); 58 } 59 60 /* note: already called with rcu_read_lock */ 61 int br_handle_frame_finish(struct sk_buff *skb) 62 { 63 const unsigned char *dest = eth_hdr(skb)->h_dest; 64 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 65 struct net_bridge *br; 66 struct net_bridge_fdb_entry *dst; 67 struct net_bridge_mdb_entry *mdst; 68 struct sk_buff *skb2; 69 bool unicast = true; 70 u16 vid = 0; 71 72 if (!p || p->state == BR_STATE_DISABLED) 73 goto drop; 74 75 if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb, &vid)) 76 goto out; 77 78 /* insert into forwarding database after filtering to avoid spoofing */ 79 br = p->br; 80 if (p->flags & BR_LEARNING) 81 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false); 82 83 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) && 84 br_multicast_rcv(br, p, skb, vid)) 85 goto drop; 86 87 if (p->state == BR_STATE_LEARNING) 88 goto drop; 89 90 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 91 92 /* The packet skb2 goes to the local host (NULL to skip). */ 93 skb2 = NULL; 94 95 if (br->dev->flags & IFF_PROMISC) 96 skb2 = skb; 97 98 dst = NULL; 99 100 if (is_broadcast_ether_addr(dest)) { 101 skb2 = skb; 102 unicast = false; 103 } else if (is_multicast_ether_addr(dest)) { 104 mdst = br_mdb_get(br, skb, vid); 105 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && 106 br_multicast_querier_exists(br, eth_hdr(skb))) { 107 if ((mdst && mdst->mglist) || 108 br_multicast_is_router(br)) 109 skb2 = skb; 110 br_multicast_forward(mdst, skb, skb2); 111 skb = NULL; 112 if (!skb2) 113 goto out; 114 } else 115 skb2 = skb; 116 117 unicast = false; 118 br->dev->stats.multicast++; 119 } else if ((dst = __br_fdb_get(br, dest, vid)) && 120 dst->is_local) { 121 skb2 = skb; 122 /* Do not forward the packet since it's local. */ 123 skb = NULL; 124 } 125 126 if (skb) { 127 if (dst) { 128 dst->used = jiffies; 129 br_forward(dst->dst, skb, skb2); 130 } else 131 br_flood_forward(br, skb, skb2, unicast); 132 } 133 134 if (skb2) 135 return br_pass_frame_up(skb2); 136 137 out: 138 return 0; 139 drop: 140 kfree_skb(skb); 141 goto out; 142 } 143 144 /* note: already called with rcu_read_lock */ 145 static int br_handle_local_finish(struct sk_buff *skb) 146 { 147 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 148 u16 vid = 0; 149 150 /* check if vlan is allowed, to avoid spoofing */ 151 if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid)) 152 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); 153 return 0; /* process further */ 154 } 155 156 /* 157 * Return NULL if skb is handled 158 * note: already called with rcu_read_lock 159 */ 160 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 161 { 162 struct net_bridge_port *p; 163 struct sk_buff *skb = *pskb; 164 const unsigned char *dest = eth_hdr(skb)->h_dest; 165 br_should_route_hook_t *rhook; 166 167 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 168 return RX_HANDLER_PASS; 169 170 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 171 goto drop; 172 173 skb = skb_share_check(skb, GFP_ATOMIC); 174 if (!skb) 175 return RX_HANDLER_CONSUMED; 176 177 p = br_port_get_rcu(skb->dev); 178 179 if (unlikely(is_link_local_ether_addr(dest))) { 180 u16 fwd_mask = p->br->group_fwd_mask_required; 181 182 /* 183 * See IEEE 802.1D Table 7-10 Reserved addresses 184 * 185 * Assignment Value 186 * Bridge Group Address 01-80-C2-00-00-00 187 * (MAC Control) 802.3 01-80-C2-00-00-01 188 * (Link Aggregation) 802.3 01-80-C2-00-00-02 189 * 802.1X PAE address 01-80-C2-00-00-03 190 * 191 * 802.1AB LLDP 01-80-C2-00-00-0E 192 * 193 * Others reserved for future standardization 194 */ 195 switch (dest[5]) { 196 case 0x00: /* Bridge Group Address */ 197 /* If STP is turned off, 198 then must forward to keep loop detection */ 199 if (p->br->stp_enabled == BR_NO_STP || 200 fwd_mask & (1u << dest[5])) 201 goto forward; 202 break; 203 204 case 0x01: /* IEEE MAC (Pause) */ 205 goto drop; 206 207 default: 208 /* Allow selective forwarding for most other protocols */ 209 fwd_mask |= p->br->group_fwd_mask; 210 if (fwd_mask & (1u << dest[5])) 211 goto forward; 212 } 213 214 /* Deliver packet to local host only */ 215 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, 216 NULL, br_handle_local_finish)) { 217 return RX_HANDLER_CONSUMED; /* consumed by filter */ 218 } else { 219 *pskb = skb; 220 return RX_HANDLER_PASS; /* continue processing */ 221 } 222 } 223 224 forward: 225 switch (p->state) { 226 case BR_STATE_FORWARDING: 227 rhook = rcu_dereference(br_should_route_hook); 228 if (rhook) { 229 if ((*rhook)(skb)) { 230 *pskb = skb; 231 return RX_HANDLER_PASS; 232 } 233 dest = eth_hdr(skb)->h_dest; 234 } 235 /* fall through */ 236 case BR_STATE_LEARNING: 237 if (ether_addr_equal(p->br->dev->dev_addr, dest)) 238 skb->pkt_type = PACKET_HOST; 239 240 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, 241 br_handle_frame_finish); 242 break; 243 default: 244 drop: 245 kfree_skb(skb); 246 } 247 return RX_HANDLER_CONSUMED; 248 } 249