| 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/neighbour.h> |
| 20 | #include <net/arp.h> |
| 21 | #include <linux/export.h> |
| 22 | #include <linux/rculist.h> |
| 23 | #include "br_private.h" |
| 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 |
| 30 | br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb) |
| 31 | { |
| 32 | return netif_receive_skb(skb); |
| 33 | } |
| 34 | |
| 35 | static int br_pass_frame_up(struct sk_buff *skb) |
| 36 | { |
| 37 | struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; |
| 38 | struct net_bridge *br = netdev_priv(brdev); |
| 39 | struct net_bridge_vlan_group *vg; |
| 40 | struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats); |
| 41 | |
| 42 | u64_stats_update_begin(&brstats->syncp); |
| 43 | brstats->rx_packets++; |
| 44 | brstats->rx_bytes += skb->len; |
| 45 | u64_stats_update_end(&brstats->syncp); |
| 46 | |
| 47 | vg = br_vlan_group_rcu(br); |
| 48 | /* Bridge is just like any other port. Make sure the |
| 49 | * packet is allowed except in promisc modue when someone |
| 50 | * may be running packet capture. |
| 51 | */ |
| 52 | if (!(brdev->flags & IFF_PROMISC) && |
| 53 | !br_allowed_egress(vg, skb)) { |
| 54 | kfree_skb(skb); |
| 55 | return NET_RX_DROP; |
| 56 | } |
| 57 | |
| 58 | indev = skb->dev; |
| 59 | skb->dev = brdev; |
| 60 | skb = br_handle_vlan(br, vg, skb); |
| 61 | if (!skb) |
| 62 | return NET_RX_DROP; |
| 63 | /* update the multicast stats if the packet is IGMP/MLD */ |
| 64 | br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb), |
| 65 | BR_MCAST_DIR_TX); |
| 66 | |
| 67 | return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, |
| 68 | dev_net(indev), NULL, skb, indev, NULL, |
| 69 | br_netif_receive_skb); |
| 70 | } |
| 71 | |
| 72 | static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br, |
| 73 | u16 vid, struct net_bridge_port *p) |
| 74 | { |
| 75 | struct net_device *dev = br->dev; |
| 76 | struct neighbour *n; |
| 77 | struct arphdr *parp; |
| 78 | u8 *arpptr, *sha; |
| 79 | __be32 sip, tip; |
| 80 | |
| 81 | BR_INPUT_SKB_CB(skb)->proxyarp_replied = false; |
| 82 | |
| 83 | if (dev->flags & IFF_NOARP) |
| 84 | return; |
| 85 | |
| 86 | if (!pskb_may_pull(skb, arp_hdr_len(dev))) { |
| 87 | dev->stats.tx_dropped++; |
| 88 | return; |
| 89 | } |
| 90 | parp = arp_hdr(skb); |
| 91 | |
| 92 | if (parp->ar_pro != htons(ETH_P_IP) || |
| 93 | parp->ar_op != htons(ARPOP_REQUEST) || |
| 94 | parp->ar_hln != dev->addr_len || |
| 95 | parp->ar_pln != 4) |
| 96 | return; |
| 97 | |
| 98 | arpptr = (u8 *)parp + sizeof(struct arphdr); |
| 99 | sha = arpptr; |
| 100 | arpptr += dev->addr_len; /* sha */ |
| 101 | memcpy(&sip, arpptr, sizeof(sip)); |
| 102 | arpptr += sizeof(sip); |
| 103 | arpptr += dev->addr_len; /* tha */ |
| 104 | memcpy(&tip, arpptr, sizeof(tip)); |
| 105 | |
| 106 | if (ipv4_is_loopback(tip) || |
| 107 | ipv4_is_multicast(tip)) |
| 108 | return; |
| 109 | |
| 110 | n = neigh_lookup(&arp_tbl, &tip, dev); |
| 111 | if (n) { |
| 112 | struct net_bridge_fdb_entry *f; |
| 113 | |
| 114 | if (!(n->nud_state & NUD_VALID)) { |
| 115 | neigh_release(n); |
| 116 | return; |
| 117 | } |
| 118 | |
| 119 | f = __br_fdb_get(br, n->ha, vid); |
| 120 | if (f && ((p->flags & BR_PROXYARP) || |
| 121 | (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) { |
| 122 | arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip, |
| 123 | sha, n->ha, sha); |
| 124 | BR_INPUT_SKB_CB(skb)->proxyarp_replied = true; |
| 125 | } |
| 126 | |
| 127 | neigh_release(n); |
| 128 | } |
| 129 | } |
| 130 | |
| 131 | /* note: already called with rcu_read_lock */ |
| 132 | int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
| 133 | { |
| 134 | bool local_rcv = false, mcast_hit = false, unicast = true; |
| 135 | struct net_bridge_port *p = br_port_get_rcu(skb->dev); |
| 136 | const unsigned char *dest = eth_hdr(skb)->h_dest; |
| 137 | struct net_bridge_fdb_entry *dst = NULL; |
| 138 | struct net_bridge_mdb_entry *mdst; |
| 139 | struct net_bridge *br; |
| 140 | u16 vid = 0; |
| 141 | |
| 142 | if (!p || p->state == BR_STATE_DISABLED) |
| 143 | goto drop; |
| 144 | |
| 145 | if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid)) |
| 146 | goto out; |
| 147 | |
| 148 | /* insert into forwarding database after filtering to avoid spoofing */ |
| 149 | br = p->br; |
| 150 | if (p->flags & BR_LEARNING) |
| 151 | br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false); |
| 152 | |
| 153 | if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) && |
| 154 | br_multicast_rcv(br, p, skb, vid)) |
| 155 | goto drop; |
| 156 | |
| 157 | if (p->state == BR_STATE_LEARNING) |
| 158 | goto drop; |
| 159 | |
| 160 | BR_INPUT_SKB_CB(skb)->brdev = br->dev; |
| 161 | |
| 162 | local_rcv = !!(br->dev->flags & IFF_PROMISC); |
| 163 | |
| 164 | if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP)) |
| 165 | br_do_proxy_arp(skb, br, vid, p); |
| 166 | |
| 167 | if (is_broadcast_ether_addr(dest)) { |
| 168 | local_rcv = true; |
| 169 | unicast = false; |
| 170 | } else if (is_multicast_ether_addr(dest)) { |
| 171 | mdst = br_mdb_get(br, skb, vid); |
| 172 | if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && |
| 173 | br_multicast_querier_exists(br, eth_hdr(skb))) { |
| 174 | if ((mdst && mdst->mglist) || |
| 175 | br_multicast_is_router(br)) { |
| 176 | local_rcv = true; |
| 177 | br->dev->stats.multicast++; |
| 178 | } |
| 179 | mcast_hit = true; |
| 180 | } else { |
| 181 | local_rcv = true; |
| 182 | br->dev->stats.multicast++; |
| 183 | } |
| 184 | unicast = false; |
| 185 | } else if ((dst = __br_fdb_get(br, dest, vid)) && dst->is_local) { |
| 186 | /* Do not forward the packet since it's local. */ |
| 187 | return br_pass_frame_up(skb); |
| 188 | } |
| 189 | |
| 190 | if (dst) { |
| 191 | dst->used = jiffies; |
| 192 | br_forward(dst->dst, skb, local_rcv, false); |
| 193 | } else { |
| 194 | if (!mcast_hit) |
| 195 | br_flood(br, skb, unicast, local_rcv, false); |
| 196 | else |
| 197 | br_multicast_flood(mdst, skb, local_rcv, false); |
| 198 | } |
| 199 | |
| 200 | if (local_rcv) |
| 201 | return br_pass_frame_up(skb); |
| 202 | |
| 203 | out: |
| 204 | return 0; |
| 205 | drop: |
| 206 | kfree_skb(skb); |
| 207 | goto out; |
| 208 | } |
| 209 | EXPORT_SYMBOL_GPL(br_handle_frame_finish); |
| 210 | |
| 211 | static void __br_handle_local_finish(struct sk_buff *skb) |
| 212 | { |
| 213 | struct net_bridge_port *p = br_port_get_rcu(skb->dev); |
| 214 | u16 vid = 0; |
| 215 | |
| 216 | /* check if vlan is allowed, to avoid spoofing */ |
| 217 | if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid)) |
| 218 | br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); |
| 219 | } |
| 220 | |
| 221 | /* note: already called with rcu_read_lock */ |
| 222 | static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
| 223 | { |
| 224 | struct net_bridge_port *p = br_port_get_rcu(skb->dev); |
| 225 | |
| 226 | __br_handle_local_finish(skb); |
| 227 | |
| 228 | BR_INPUT_SKB_CB(skb)->brdev = p->br->dev; |
| 229 | br_pass_frame_up(skb); |
| 230 | return 0; |
| 231 | } |
| 232 | |
| 233 | /* |
| 234 | * Return NULL if skb is handled |
| 235 | * note: already called with rcu_read_lock |
| 236 | */ |
| 237 | rx_handler_result_t br_handle_frame(struct sk_buff **pskb) |
| 238 | { |
| 239 | struct net_bridge_port *p; |
| 240 | struct sk_buff *skb = *pskb; |
| 241 | const unsigned char *dest = eth_hdr(skb)->h_dest; |
| 242 | br_should_route_hook_t *rhook; |
| 243 | |
| 244 | if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) |
| 245 | return RX_HANDLER_PASS; |
| 246 | |
| 247 | if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) |
| 248 | goto drop; |
| 249 | |
| 250 | skb = skb_share_check(skb, GFP_ATOMIC); |
| 251 | if (!skb) |
| 252 | return RX_HANDLER_CONSUMED; |
| 253 | |
| 254 | p = br_port_get_rcu(skb->dev); |
| 255 | |
| 256 | if (unlikely(is_link_local_ether_addr(dest))) { |
| 257 | u16 fwd_mask = p->br->group_fwd_mask_required; |
| 258 | |
| 259 | /* |
| 260 | * See IEEE 802.1D Table 7-10 Reserved addresses |
| 261 | * |
| 262 | * Assignment Value |
| 263 | * Bridge Group Address 01-80-C2-00-00-00 |
| 264 | * (MAC Control) 802.3 01-80-C2-00-00-01 |
| 265 | * (Link Aggregation) 802.3 01-80-C2-00-00-02 |
| 266 | * 802.1X PAE address 01-80-C2-00-00-03 |
| 267 | * |
| 268 | * 802.1AB LLDP 01-80-C2-00-00-0E |
| 269 | * |
| 270 | * Others reserved for future standardization |
| 271 | */ |
| 272 | switch (dest[5]) { |
| 273 | case 0x00: /* Bridge Group Address */ |
| 274 | /* If STP is turned off, |
| 275 | then must forward to keep loop detection */ |
| 276 | if (p->br->stp_enabled == BR_NO_STP || |
| 277 | fwd_mask & (1u << dest[5])) |
| 278 | goto forward; |
| 279 | *pskb = skb; |
| 280 | __br_handle_local_finish(skb); |
| 281 | return RX_HANDLER_PASS; |
| 282 | |
| 283 | case 0x01: /* IEEE MAC (Pause) */ |
| 284 | goto drop; |
| 285 | |
| 286 | case 0x0E: /* 802.1AB LLDP */ |
| 287 | fwd_mask |= p->br->group_fwd_mask; |
| 288 | if (fwd_mask & (1u << dest[5])) |
| 289 | goto forward; |
| 290 | *pskb = skb; |
| 291 | __br_handle_local_finish(skb); |
| 292 | return RX_HANDLER_PASS; |
| 293 | |
| 294 | default: |
| 295 | /* Allow selective forwarding for most other protocols */ |
| 296 | fwd_mask |= p->br->group_fwd_mask; |
| 297 | if (fwd_mask & (1u << dest[5])) |
| 298 | goto forward; |
| 299 | } |
| 300 | |
| 301 | /* Deliver packet to local host only */ |
| 302 | NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev), |
| 303 | NULL, skb, skb->dev, NULL, br_handle_local_finish); |
| 304 | return RX_HANDLER_CONSUMED; |
| 305 | } |
| 306 | |
| 307 | forward: |
| 308 | switch (p->state) { |
| 309 | case BR_STATE_FORWARDING: |
| 310 | rhook = rcu_dereference(br_should_route_hook); |
| 311 | if (rhook) { |
| 312 | if ((*rhook)(skb)) { |
| 313 | *pskb = skb; |
| 314 | return RX_HANDLER_PASS; |
| 315 | } |
| 316 | dest = eth_hdr(skb)->h_dest; |
| 317 | } |
| 318 | /* fall through */ |
| 319 | case BR_STATE_LEARNING: |
| 320 | if (ether_addr_equal(p->br->dev->dev_addr, dest)) |
| 321 | skb->pkt_type = PACKET_HOST; |
| 322 | |
| 323 | NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, |
| 324 | dev_net(skb->dev), NULL, skb, skb->dev, NULL, |
| 325 | br_handle_frame_finish); |
| 326 | break; |
| 327 | default: |
| 328 | drop: |
| 329 | kfree_skb(skb); |
| 330 | } |
| 331 | return RX_HANDLER_CONSUMED; |
| 332 | } |