| 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 | br_multicast_querier_exists(br)) { |
| 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 | } |