net/bridge/br_input.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      Handle incoming frames
   4  *      Linux ethernet bridge
   5  *
   6  *      Authors:
   7  *      Lennert Buytenhek               <buytenh@gnu.org>
   8  */
   9
  10 #include <linux/slab.h>
  11 #include <linux/kernel.h>
  12 #include <linux/netdevice.h>
  13 #include <linux/etherdevice.h>
  14 #include <linux/netfilter_bridge.h>
  15 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
  16 #include <net/netfilter/nf_queue.h>
  17 #endif
  18 #include <linux/neighbour.h>
  19 #include <net/arp.h>
  20 #include <linux/export.h>
  21 #include <linux/rculist.h>
  22 #include "br_private.h"
  23 #include "br_private_tunnel.h"
  24
  25 static int
  26 br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
  27 {
  28         br_drop_fake_rtable(skb);
  29         return netif_receive_skb(skb);
  30 }
  31
  32 static int br_pass_frame_up(struct sk_buff *skb)
  33 {
  34         struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
  35         struct net_bridge *br = netdev_priv(brdev);
  36         struct net_bridge_vlan_group *vg;
  37         struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
  38
  39         u64_stats_update_begin(&brstats->syncp);
  40         brstats->rx_packets++;
  41         brstats->rx_bytes += skb->len;
  42         u64_stats_update_end(&brstats->syncp);
  43
  44         vg = br_vlan_group_rcu(br);
  45         /* Bridge is just like any other port.  Make sure the
  46          * packet is allowed except in promisc modue when someone
  47          * may be running packet capture.
  48          */
  49         if (!(brdev->flags & IFF_PROMISC) &&
  50             !br_allowed_egress(vg, skb)) {
  51                 kfree_skb(skb);
  52                 return NET_RX_DROP;
  53         }
  54
  55         indev = skb->dev;
  56         skb->dev = brdev;
  57         skb = br_handle_vlan(br, NULL, vg, skb);
  58         if (!skb)
  59                 return NET_RX_DROP;
  60         /* update the multicast stats if the packet is IGMP/MLD */
  61         br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
  62                            BR_MCAST_DIR_TX);
  63
  64         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
  65                        dev_net(indev), NULL, skb, indev, NULL,
  66                        br_netif_receive_skb);
  67 }
  68
  69 /* note: already called with rcu_read_lock */
  70 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
  71 {
  72         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
  73         enum br_pkt_type pkt_type = BR_PKT_UNICAST;
  74         struct net_bridge_fdb_entry *dst = NULL;
  75         struct net_bridge_mdb_entry *mdst;
  76         bool local_rcv, mcast_hit = false;
  77         struct net_bridge *br;
  78         u16 vid = 0;
  79         u8 state;
  80
  81         if (!p || p->state == BR_STATE_DISABLED)
  82                 goto drop;
  83
  84         state = p->state;
  85         if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid,
  86                                 &state))
  87                 goto out;
  88
  89         nbp_switchdev_frame_mark(p, skb);
  90
  91         /* insert into forwarding database after filtering to avoid spoofing */
  92         br = p->br;
  93         if (p->flags & BR_LEARNING)
  94                 br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0);
  95
  96         local_rcv = !!(br->dev->flags & IFF_PROMISC);
  97         if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
  98                 /* by definition the broadcast is also a multicast address */
  99                 if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) {
 100                         pkt_type = BR_PKT_BROADCAST;
 101                         local_rcv = true;
 102                 } else {
 103                         pkt_type = BR_PKT_MULTICAST;
 104                         if (br_multicast_rcv(br, p, skb, vid))
 105                                 goto drop;
 106                 }
 107         }
 108
 109         if (state == BR_STATE_LEARNING)
 110                 goto drop;
 111
 112         BR_INPUT_SKB_CB(skb)->brdev = br->dev;
 113         BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED);
 114
 115         if (IS_ENABLED(CONFIG_INET) &&
 116             (skb->protocol == htons(ETH_P_ARP) ||
 117              skb->protocol == htons(ETH_P_RARP))) {
 118                 br_do_proxy_suppress_arp(skb, br, vid, p);
 119         } else if (IS_ENABLED(CONFIG_IPV6) &&
 120                    skb->protocol == htons(ETH_P_IPV6) &&
 121                    br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
 122                    pskb_may_pull(skb, sizeof(struct ipv6hdr) +
 123                                  sizeof(struct nd_msg)) &&
 124                    ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
 125                         struct nd_msg *msg, _msg;
 126
 127                         msg = br_is_nd_neigh_msg(skb, &_msg);
 128                         if (msg)
 129                                 br_do_suppress_nd(skb, br, vid, p, msg);
 130         }
 131
 132         switch (pkt_type) {
 133         case BR_PKT_MULTICAST:
 134                 mdst = br_mdb_get(br, skb, vid);
 135                 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
 136                     br_multicast_querier_exists(br, eth_hdr(skb))) {
 137                         if ((mdst && mdst->host_joined) ||
 138                             br_multicast_is_router(br)) {
 139                                 local_rcv = true;
 140                                 br->dev->stats.multicast++;
 141                         }
 142                         mcast_hit = true;
 143                 } else {
 144                         local_rcv = true;
 145                         br->dev->stats.multicast++;
 146                 }
 147                 break;
 148         case BR_PKT_UNICAST:
 149                 dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid);
 150         default:
 151                 break;
 152         }
 153
 154         if (dst) {
 155                 unsigned long now = jiffies;
 156
 157                 if (test_bit(BR_FDB_LOCAL, &dst->flags))
 158                         return br_pass_frame_up(skb);
 159
 160                 if (now != dst->used)
 161                         dst->used = now;
 162                 br_forward(dst->dst, skb, local_rcv, false);
 163         } else {
 164                 if (!mcast_hit)
 165                         br_flood(br, skb, pkt_type, local_rcv, false);
 166                 else
 167                         br_multicast_flood(mdst, skb, local_rcv, false);
 168         }
 169
 170         if (local_rcv)
 171                 return br_pass_frame_up(skb);
 172
 173 out:
 174         return 0;
 175 drop:
 176         kfree_skb(skb);
 177         goto out;
 178 }
 179 EXPORT_SYMBOL_GPL(br_handle_frame_finish);
 180
 181 static void __br_handle_local_finish(struct sk_buff *skb)
 182 {
 183         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
 184         u16 vid = 0;
 185
 186         /* check if vlan is allowed, to avoid spoofing */
 187         if ((p->flags & BR_LEARNING) &&
 188             nbp_state_should_learn(p) &&
 189             !br_opt_get(p->br, BROPT_NO_LL_LEARN) &&
 190             br_should_learn(p, skb, &vid))
 191                 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0);
 192 }
 193
 194 /* note: already called with rcu_read_lock */
 195 static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 196 {
 197         __br_handle_local_finish(skb);
 198
 199         /* return 1 to signal the okfn() was called so it's ok to use the skb */
 200         return 1;
 201 }
 202
 203 static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb)
 204 {
 205 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 206         struct nf_hook_entries *e = NULL;
 207         struct nf_hook_state state;
 208         unsigned int verdict, i;
 209         struct net *net;
 210         int ret;
 211
 212         net = dev_net(skb->dev);
 213 #ifdef HAVE_JUMP_LABEL
 214         if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING]))
 215                 goto frame_finish;
 216 #endif
 217
 218         e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]);
 219         if (!e)
 220                 goto frame_finish;
 221
 222         nf_hook_state_init(&state, NF_BR_PRE_ROUTING,
 223                            NFPROTO_BRIDGE, skb->dev, NULL, NULL,
 224                            net, br_handle_frame_finish);
 225
 226         for (i = 0; i < e->num_hook_entries; i++) {
 227                 verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state);
 228                 switch (verdict & NF_VERDICT_MASK) {
 229                 case NF_ACCEPT:
 230                         if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) {
 231                                 *pskb = skb;
 232                                 return RX_HANDLER_PASS;
 233                         }
 234                         break;
 235                 case NF_DROP:
 236                         kfree_skb(skb);
 237                         return RX_HANDLER_CONSUMED;
 238                 case NF_QUEUE:
 239                         ret = nf_queue(skb, &state, i, verdict);
 240                         if (ret == 1)
 241                                 continue;
 242                         return RX_HANDLER_CONSUMED;
 243                 default: /* STOLEN */
 244                         return RX_HANDLER_CONSUMED;
 245                 }
 246         }
 247 frame_finish:
 248         net = dev_net(skb->dev);
 249         br_handle_frame_finish(net, NULL, skb);
 250 #else
 251         br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
 252 #endif
 253         return RX_HANDLER_CONSUMED;
 254 }
 255
 256 /*
 257  * Return NULL if skb is handled
 258  * note: already called with rcu_read_lock
 259  */
 260 rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 261 {
 262         struct net_bridge_port *p;
 263         struct sk_buff *skb = *pskb;
 264         const unsigned char *dest = eth_hdr(skb)->h_dest;
 265
 266         if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 267                 return RX_HANDLER_PASS;
 268
 269         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 270                 goto drop;
 271
 272         skb = skb_share_check(skb, GFP_ATOMIC);
 273         if (!skb)
 274                 return RX_HANDLER_CONSUMED;
 275
 276         memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
 277
 278         p = br_port_get_rcu(skb->dev);
 279         if (p->flags & BR_VLAN_TUNNEL) {
 280                 if (br_handle_ingress_vlan_tunnel(skb, p,
 281                                                   nbp_vlan_group_rcu(p)))
 282                         goto drop;
 283         }
 284
 285         if (unlikely(is_link_local_ether_addr(dest))) {
 286                 u16 fwd_mask = p->br->group_fwd_mask_required;
 287
 288                 /*
 289                  * See IEEE 802.1D Table 7-10 Reserved addresses
 290                  *
 291                  * Assignment                           Value
 292                  * Bridge Group Address         01-80-C2-00-00-00
 293                  * (MAC Control) 802.3          01-80-C2-00-00-01
 294                  * (Link Aggregation) 802.3     01-80-C2-00-00-02
 295                  * 802.1X PAE address           01-80-C2-00-00-03
 296                  *
 297                  * 802.1AB LLDP                 01-80-C2-00-00-0E
 298                  *
 299                  * Others reserved for future standardization
 300                  */
 301                 fwd_mask |= p->group_fwd_mask;
 302                 switch (dest[5]) {
 303                 case 0x00:      /* Bridge Group Address */
 304                         /* If STP is turned off,
 305                            then must forward to keep loop detection */
 306                         if (p->br->stp_enabled == BR_NO_STP ||
 307                             fwd_mask & (1u << dest[5]))
 308                                 goto forward;
 309                         *pskb = skb;
 310                         __br_handle_local_finish(skb);
 311                         return RX_HANDLER_PASS;
 312
 313                 case 0x01:      /* IEEE MAC (Pause) */
 314                         goto drop;
 315
 316                 case 0x0E:      /* 802.1AB LLDP */
 317                         fwd_mask |= p->br->group_fwd_mask;
 318                         if (fwd_mask & (1u << dest[5]))
 319                                 goto forward;
 320                         *pskb = skb;
 321                         __br_handle_local_finish(skb);
 322                         return RX_HANDLER_PASS;
 323
 324                 default:
 325                         /* Allow selective forwarding for most other protocols */
 326                         fwd_mask |= p->br->group_fwd_mask;
 327                         if (fwd_mask & (1u << dest[5]))
 328                                 goto forward;
 329                 }
 330
 331                 /* The else clause should be hit when nf_hook():
 332                  *   - returns < 0 (drop/error)
 333                  *   - returns = 0 (stolen/nf_queue)
 334                  * Thus return 1 from the okfn() to signal the skb is ok to pass
 335                  */
 336                 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
 337                             dev_net(skb->dev), NULL, skb, skb->dev, NULL,
 338                             br_handle_local_finish) == 1) {
 339                         return RX_HANDLER_PASS;
 340                 } else {
 341                         return RX_HANDLER_CONSUMED;
 342                 }
 343         }
 344
 345 forward:
 346         switch (p->state) {
 347         case BR_STATE_FORWARDING:
 348         case BR_STATE_LEARNING:
 349                 if (ether_addr_equal(p->br->dev->dev_addr, dest))
 350                         skb->pkt_type = PACKET_HOST;
 351
 352                 return nf_hook_bridge_pre(skb, pskb);
 353         default:
 354 drop:
 355                 kfree_skb(skb);
 356         }
 357         return RX_HANDLER_CONSUMED;
 358 }