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 "br_private.h" 21 22 /* Bridge group multicast address 802.1d (pg 51). */ 23 const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 }; 24 25 /* Hook for brouter */ 26 br_should_route_hook_t __rcu *br_should_route_hook __read_mostly; 27 EXPORT_SYMBOL(br_should_route_hook); 28 29 static int br_pass_frame_up(struct sk_buff *skb) 30 { 31 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; 32 struct net_bridge *br = netdev_priv(brdev); 33 struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats); 34 35 u64_stats_update_begin(&brstats->syncp); 36 brstats->rx_packets++; 37 brstats->rx_bytes += skb->len; 38 u64_stats_update_end(&brstats->syncp); 39 40 indev = skb->dev; 41 skb->dev = brdev; 42 43 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL, 44 netif_receive_skb); 45 } 46 47 /* note: already called with rcu_read_lock */ 48 int br_handle_frame_finish(struct sk_buff *skb) 49 { 50 const unsigned char *dest = eth_hdr(skb)->h_dest; 51 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 52 struct net_bridge *br; 53 struct net_bridge_fdb_entry *dst; 54 struct net_bridge_mdb_entry *mdst; 55 struct sk_buff *skb2; 56 57 if (!p || p->state == BR_STATE_DISABLED) 58 goto drop; 59 60 /* insert into forwarding database after filtering to avoid spoofing */ 61 br = p->br; 62 br_fdb_update(br, p, eth_hdr(skb)->h_source); 63 64 if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) && 65 br_multicast_rcv(br, p, skb)) 66 goto drop; 67 68 if (p->state == BR_STATE_LEARNING) 69 goto drop; 70 71 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 72 73 /* The packet skb2 goes to the local host (NULL to skip). */ 74 skb2 = NULL; 75 76 if (br->dev->flags & IFF_PROMISC) 77 skb2 = skb; 78 79 dst = NULL; 80 81 if (is_broadcast_ether_addr(dest)) 82 skb2 = skb; 83 else if (is_multicast_ether_addr(dest)) { 84 mdst = br_mdb_get(br, skb); 85 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) { 86 if ((mdst && mdst->mglist) || 87 br_multicast_is_router(br)) 88 skb2 = skb; 89 br_multicast_forward(mdst, skb, skb2); 90 skb = NULL; 91 if (!skb2) 92 goto out; 93 } else 94 skb2 = skb; 95 96 br->dev->stats.multicast++; 97 } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) { 98 skb2 = skb; 99 /* Do not forward the packet since it's local. */ 100 skb = NULL; 101 } 102 103 if (skb) { 104 if (dst) { 105 dst->used = jiffies; 106 br_forward(dst->dst, skb, skb2); 107 } else 108 br_flood_forward(br, skb, skb2); 109 } 110 111 if (skb2) 112 return br_pass_frame_up(skb2); 113 114 out: 115 return 0; 116 drop: 117 kfree_skb(skb); 118 goto out; 119 } 120 121 /* note: already called with rcu_read_lock */ 122 static int br_handle_local_finish(struct sk_buff *skb) 123 { 124 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 125 126 br_fdb_update(p->br, p, eth_hdr(skb)->h_source); 127 return 0; /* process further */ 128 } 129 130 /* Does address match the link local multicast address. 131 * 01:80:c2:00:00:0X 132 */ 133 static inline int is_link_local(const unsigned char *dest) 134 { 135 __be16 *a = (__be16 *)dest; 136 static const __be16 *b = (const __be16 *)br_group_address; 137 static const __be16 m = cpu_to_be16(0xfff0); 138 139 return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0; 140 } 141 142 /* 143 * Return NULL if skb is handled 144 * note: already called with rcu_read_lock 145 */ 146 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 147 { 148 struct net_bridge_port *p; 149 struct sk_buff *skb = *pskb; 150 const unsigned char *dest = eth_hdr(skb)->h_dest; 151 br_should_route_hook_t *rhook; 152 153 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 154 return RX_HANDLER_PASS; 155 156 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 157 goto drop; 158 159 skb = skb_share_check(skb, GFP_ATOMIC); 160 if (!skb) 161 return RX_HANDLER_CONSUMED; 162 163 p = br_port_get_rcu(skb->dev); 164 165 if (unlikely(is_link_local(dest))) { 166 /* 167 * See IEEE 802.1D Table 7-10 Reserved addresses 168 * 169 * Assignment Value 170 * Bridge Group Address 01-80-C2-00-00-00 171 * (MAC Control) 802.3 01-80-C2-00-00-01 172 * (Link Aggregation) 802.3 01-80-C2-00-00-02 173 * 802.1X PAE address 01-80-C2-00-00-03 174 * 175 * 802.1AB LLDP 01-80-C2-00-00-0E 176 * 177 * Others reserved for future standardization 178 */ 179 switch (dest[5]) { 180 case 0x00: /* Bridge Group Address */ 181 /* If STP is turned off, 182 then must forward to keep loop detection */ 183 if (p->br->stp_enabled == BR_NO_STP) 184 goto forward; 185 break; 186 187 case 0x01: /* IEEE MAC (Pause) */ 188 goto drop; 189 190 default: 191 /* Allow selective forwarding for most other protocols */ 192 if (p->br->group_fwd_mask & (1u << dest[5])) 193 goto forward; 194 } 195 196 /* Deliver packet to local host only */ 197 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, 198 NULL, br_handle_local_finish)) { 199 return RX_HANDLER_CONSUMED; /* consumed by filter */ 200 } else { 201 *pskb = skb; 202 return RX_HANDLER_PASS; /* continue processing */ 203 } 204 } 205 206 forward: 207 switch (p->state) { 208 case BR_STATE_FORWARDING: 209 rhook = rcu_dereference(br_should_route_hook); 210 if (rhook) { 211 if ((*rhook)(skb)) { 212 *pskb = skb; 213 return RX_HANDLER_PASS; 214 } 215 dest = eth_hdr(skb)->h_dest; 216 } 217 /* fall through */ 218 case BR_STATE_LEARNING: 219 if (!compare_ether_addr(p->br->dev->dev_addr, dest)) 220 skb->pkt_type = PACKET_HOST; 221 222 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, 223 br_handle_frame_finish); 224 break; 225 default: 226 drop: 227 kfree_skb(skb); 228 } 229 return RX_HANDLER_CONSUMED; 230 } 231