net/bridge/br_input.c

   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 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
  20 #include <net/netfilter/nf_queue.h>
  21 #endif
  22 #include <linux/neighbour.h>
  23 #include <net/arp.h>
  24 #include <linux/export.h>
  25 #include <linux/rculist.h>
  26 #include "br_private.h"
  27 #include "br_private_tunnel.h"
  28
  29 static int
  30 br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
  31 {
  32         br_drop_fake_rtable(skb);
  33         return netif_receive_skb(skb);
  34 }
  35
  36 static int br_pass_frame_up(struct sk_buff *skb)
  37 {
  38         struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
  39         struct net_bridge *br = netdev_priv(brdev);
  40         struct net_bridge_vlan_group *vg;
  41         struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
  42
  43         u64_stats_update_begin(&brstats->syncp);
  44         brstats->rx_packets++;
  45         brstats->rx_bytes += skb->len;
  46         u64_stats_update_end(&brstats->syncp);
  47
  48         vg = br_vlan_group_rcu(br);
  49         /* Bridge is just like any other port.  Make sure the
  50          * packet is allowed except in promisc modue when someone
  51          * may be running packet capture.
  52          */
  53         if (!(brdev->flags & IFF_PROMISC) &&
  54             !br_allowed_egress(vg, skb)) {
  55                 kfree_skb(skb);
  56                 return NET_RX_DROP;
  57         }
  58
  59         indev = skb->dev;
  60         skb->dev = brdev;
  61         skb = br_handle_vlan(br, NULL, vg, skb);
  62         if (!skb)
  63                 return NET_RX_DROP;
  64         /* update the multicast stats if the packet is IGMP/MLD */
  65         br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
  66                            BR_MCAST_DIR_TX);
  67
  68         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
  69                        dev_net(indev), NULL, skb, indev, NULL,
  70                        br_netif_receive_skb);
  71 }
  72
  73 /* note: already called with rcu_read_lock */
  74 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
  75 {
  76         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
  77         enum br_pkt_type pkt_type = BR_PKT_UNICAST;
  78         struct net_bridge_fdb_entry *dst = NULL;
  79         struct net_bridge_mdb_entry *mdst;
  80         bool local_rcv, mcast_hit = false;
  81         const unsigned char *dest;
  82         struct net_bridge *br;
  83         u16 vid = 0;
  84
  85         if (!p || p->state == BR_STATE_DISABLED)
  86                 goto drop;
  87
  88         if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid))
  89                 goto out;
  90
  91         nbp_switchdev_frame_mark(p, skb);
  92
  93         /* insert into forwarding database after filtering to avoid spoofing */
  94         br = p->br;
  95         if (p->flags & BR_LEARNING)
  96                 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);
  97
  98         local_rcv = !!(br->dev->flags & IFF_PROMISC);
  99         dest = eth_hdr(skb)->h_dest;
 100         if (is_multicast_ether_addr(dest)) {
 101                 /* by definition the broadcast is also a multicast address */
 102                 if (is_broadcast_ether_addr(dest)) {
 103                         pkt_type = BR_PKT_BROADCAST;
 104                         local_rcv = true;
 105                 } else {
 106                         pkt_type = BR_PKT_MULTICAST;
 107                         if (br_multicast_rcv(br, p, skb, vid))
 108                                 goto drop;
 109                 }
 110         }
 111
 112         if (p->state == BR_STATE_LEARNING)
 113                 goto drop;
 114
 115         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
 116         BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED);
 117
 118         if (IS_ENABLED(CONFIG_INET) &&
 119             (skb->protocol == htons(ETH_P_ARP) ||
 120              skb->protocol == htons(ETH_P_RARP))) {
 121                 br_do_proxy_suppress_arp(skb, br, vid, p);
 122         } else if (IS_ENABLED(CONFIG_IPV6) &&
 123                    skb->protocol == htons(ETH_P_IPV6) &&
 124                    br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
 125                    pskb_may_pull(skb, sizeof(struct ipv6hdr) +
 126                                  sizeof(struct nd_msg)) &&
 127                    ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
 128                         struct nd_msg *msg, _msg;
 129
 130                         msg = br_is_nd_neigh_msg(skb, &_msg);
 131                         if (msg)
 132                                 br_do_suppress_nd(skb, br, vid, p, msg);
 133         }
 134
 135         switch (pkt_type) {
 136         case BR_PKT_MULTICAST:
 137                 mdst = br_mdb_get(br, skb, vid);
 138                 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
 139                     br_multicast_querier_exists(br, eth_hdr(skb))) {
 140                         if ((mdst && mdst->host_joined) ||
 141                             br_multicast_is_router(br)) {
 142                                 local_rcv = true;
 143                                 br->dev->stats.multicast++;
 144                         }
 145                         mcast_hit = true;
 146                 } else {
 147                         local_rcv = true;
 148                         br->dev->stats.multicast++;
 149                 }
 150                 break;
 151         case BR_PKT_UNICAST:
 152                 dst = br_fdb_find_rcu(br, dest, vid);
 153         default:
 154                 break;
 155         }
 156
 157         if (dst) {
 158                 unsigned long now = jiffies;
 159
 160                 if (dst->is_local)
 161                         return br_pass_frame_up(skb);
 162
 163                 if (now != dst->used)
 164                         dst->used = now;
 165                 br_forward(dst->dst, skb, local_rcv, false);
 166         } else {
 167                 if (!mcast_hit)
 168                         br_flood(br, skb, pkt_type, local_rcv, false);
 169                 else
 170                         br_multicast_flood(mdst, skb, local_rcv, false);
 171         }
 172
 173         if (local_rcv)
 174                 return br_pass_frame_up(skb);
 175
 176 out:
 177         return 0;
 178 drop:
 179         kfree_skb(skb);
 180         goto out;
 181 }
 182 EXPORT_SYMBOL_GPL(br_handle_frame_finish);
 183
 184 static void __br_handle_local_finish(struct sk_buff *skb)
 185 {
 186         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
 187         u16 vid = 0;
 188
 189         /* check if vlan is allowed, to avoid spoofing */
 190         if ((p->flags & BR_LEARNING) &&
 191             !br_opt_get(p->br, BROPT_NO_LL_LEARN) &&
 192             br_should_learn(p, skb, &vid))
 193                 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);
 194 }
 195
 196 /* note: already called with rcu_read_lock */
 197 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 198 {
 199         __br_handle_local_finish(skb);
 200
 201         /* return 1 to signal the okfn() was called so it's ok to use the skb */
 202         return 1;
 203 }
 204
 205 static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb)
 206 {
 207 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 208         struct nf_hook_entries *e = NULL;
 209         struct nf_hook_state state;
 210         unsigned int verdict, i;
 211         struct net *net;
 212         int ret;
 213
 214         net = dev_net(skb->dev);
 215 #ifdef HAVE_JUMP_LABEL
 216         if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING]))
 217                 goto frame_finish;
 218 #endif
 219
 220         e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]);
 221         if (!e)
 222                 goto frame_finish;
 223
 224         nf_hook_state_init(&state, NF_BR_PRE_ROUTING,
 225                            NFPROTO_BRIDGE, skb->dev, NULL, NULL,
 226                            net, br_handle_frame_finish);
 227
 228         for (i = 0; i < e->num_hook_entries; i++) {
 229                 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state);
 230                 switch (verdict & NF_VERDICT_MASK) {
 231                 case NF_ACCEPT:
 232                         if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) {
 233                                 *pskb = skb;
 234                                 return RX_HANDLER_PASS;
 235                         }
 236                         break;
 237                 case NF_DROP:
 238                         kfree_skb(skb);
 239                         return RX_HANDLER_CONSUMED;
 240                 case NF_QUEUE:
 241                         ret = nf_queue(skb, &state, e, i, verdict);
 242                         if (ret == 1)
 243                                 continue;
 244                         return RX_HANDLER_CONSUMED;
 245                 default: /* STOLEN */
 246                         return RX_HANDLER_CONSUMED;
 247                 }
 248         }
 249 frame_finish:
 250         net = dev_net(skb->dev);
 251         br_handle_frame_finish(net, NULL, skb);
 252 #else
 253         br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
 254 #endif
 255         return RX_HANDLER_CONSUMED;
 256 }
 257
 258 /*
 259  * Return NULL if skb is handled
 260  * note: already called with rcu_read_lock
 261  */
 262 rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 263 {
 264         struct net_bridge_port *p;
 265         struct sk_buff *skb = *pskb;
 266         const unsigned char *dest = eth_hdr(skb)->h_dest;
 267
 268         if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 269                 return RX_HANDLER_PASS;
 270
 271         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 272                 goto drop;
 273
 274         skb = skb_share_check(skb, GFP_ATOMIC);
 275         if (!skb)
 276                 return RX_HANDLER_CONSUMED;
 277
 278         memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
 279
 280         p = br_port_get_rcu(skb->dev);
 281         if (p->flags & BR_VLAN_TUNNEL) {
 282                 if (br_handle_ingress_vlan_tunnel(skb, p,
 283                                                   nbp_vlan_group_rcu(p)))
 284                         goto drop;
 285         }
 286
 287         if (unlikely(is_link_local_ether_addr(dest))) {
 288                 u16 fwd_mask = p->br->group_fwd_mask_required;
 289
 290                 /*
 291                  * See IEEE 802.1D Table 7-10 Reserved addresses
 292                  *
 293                  * Assignment                           Value
 294                  * Bridge Group Address         01-80-C2-00-00-00
 295                  * (MAC Control) 802.3          01-80-C2-00-00-01
 296                  * (Link Aggregation) 802.3     01-80-C2-00-00-02
 297                  * 802.1X PAE address           01-80-C2-00-00-03
 298                  *
 299                  * 802.1AB LLDP                 01-80-C2-00-00-0E
 300                  *
 301                  * Others reserved for future standardization
 302                  */
 303                 fwd_mask |= p->group_fwd_mask;
 304                 switch (dest[5]) {
 305                 case 0x00:      /* Bridge Group Address */
 306                         /* If STP is turned off,
 307                            then must forward to keep loop detection */
 308                         if (p->br->stp_enabled == BR_NO_STP ||
 309                             fwd_mask & (1u << dest[5]))
 310                                 goto forward;
 311                         *pskb = skb;
 312                         __br_handle_local_finish(skb);
 313                         return RX_HANDLER_PASS;
 314
 315                 case 0x01:      /* IEEE MAC (Pause) */
 316                         goto drop;
 317
 318                 case 0x0E:      /* 802.1AB LLDP */
 319                         fwd_mask |= p->br->group_fwd_mask;
 320                         if (fwd_mask & (1u << dest[5]))
 321                                 goto forward;
 322                         *pskb = skb;
 323                         __br_handle_local_finish(skb);
 324                         return RX_HANDLER_PASS;
 325
 326                 default:
 327                         /* Allow selective forwarding for most other protocols */
 328                         fwd_mask |= p->br->group_fwd_mask;
 329                         if (fwd_mask & (1u << dest[5]))
 330                                 goto forward;
 331                 }
 332
 333                 /* The else clause should be hit when nf_hook():
 334                  *   - returns < 0 (drop/error)
 335                  *   - returns = 0 (stolen/nf_queue)
 336                  * Thus return 1 from the okfn() to signal the skb is ok to pass
 337                  */
 338                 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
 339                             dev_net(skb->dev), NULL, skb, skb->dev, NULL,
 340                             br_handle_local_finish) == 1) {
 341                         return RX_HANDLER_PASS;
 342                 } else {
 343                         return RX_HANDLER_CONSUMED;
 344                 }
 345         }
 346
 347 forward:
 348         switch (p->state) {
 349         case BR_STATE_FORWARDING:
 350         case BR_STATE_LEARNING:
 351                 if (ether_addr_equal(p->br->dev->dev_addr, dest))
 352                         skb->pkt_type = PACKET_HOST;
 353
 354                 return nf_hook_bridge_pre(skb, pskb);
 355         default:
 356 drop:
 357                 kfree_skb(skb);
 358         }
 359         return RX_HANDLER_CONSUMED;
 360 }