LXR linux/net/bridge/br

   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 <net/dsa.h>
  21#include <linux/export.h>
  22#include <linux/rculist.h>
  23#include "br_private.h"
  24#include "br_private_tunnel.h"
  25
  26static int
  27br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
  28{
  29        br_drop_fake_rtable(skb);
  30        return netif_receive_skb(skb);
  31}
  32
  33static int br_pass_frame_up(struct sk_buff *skb)
  34{
  35        struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
  36        struct net_bridge *br = netdev_priv(brdev);
  37        struct net_bridge_vlan_group *vg;
  38
  39        dev_sw_netstats_rx_add(brdev, skb->len);
  40
  41        vg = br_vlan_group_rcu(br);
  42        /* Bridge is just like any other port.  Make sure the
  43         * packet is allowed except in promisc mode when someone
  44         * may be running packet capture.
  45         */
  46        if (!(brdev->flags & IFF_PROMISC) &&
  47            !br_allowed_egress(vg, skb)) {
  48                kfree_skb(skb);
  49                return NET_RX_DROP;
  50        }
  51
  52        indev = skb->dev;
  53        skb->dev = brdev;
  54        skb = br_handle_vlan(br, NULL, vg, skb);
  55        if (!skb)
  56                return NET_RX_DROP;
  57        /* update the multicast stats if the packet is IGMP/MLD */
  58        br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
  59                           BR_MCAST_DIR_TX);
  60
  61        return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
  62                       dev_net(indev), NULL, skb, indev, NULL,
  63                       br_netif_receive_skb);
  64}
  65
  66/* note: already called with rcu_read_lock */
  67int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
  68{
  69        struct net_bridge_port *p = br_port_get_rcu(skb->dev);
  70        enum br_pkt_type pkt_type = BR_PKT_UNICAST;
  71        struct net_bridge_fdb_entry *dst = NULL;
  72        struct net_bridge_mcast_port *pmctx;
  73        struct net_bridge_mdb_entry *mdst;
  74        bool local_rcv, mcast_hit = false;
  75        struct net_bridge_mcast *brmctx;
  76        struct net_bridge_vlan *vlan;
  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        brmctx = &p->br->multicast_ctx;
  85        pmctx = &p->multicast_ctx;
  86        state = p->state;
  87        if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid,
  88                                &state, &vlan))
  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, 0);
  97
  98        local_rcv = !!(br->dev->flags & IFF_PROMISC);
  99        if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
 100                /* by definition the broadcast is also a multicast address */
 101                if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) {
 102                        pkt_type = BR_PKT_BROADCAST;
 103                        local_rcv = true;
 104                } else {
 105                        pkt_type = BR_PKT_MULTICAST;
 106                        if (br_multicast_rcv(&brmctx, &pmctx, vlan, skb, vid))
 107                                goto drop;
 108                }
 109        }
 110
 111        if (state == BR_STATE_LEARNING)
 112                goto drop;
 113
 114        BR_INPUT_SKB_CB(skb)->brdev = br->dev;
 115        BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED);
 116
 117        if (IS_ENABLED(CONFIG_INET) &&
 118            (skb->protocol == htons(ETH_P_ARP) ||
 119             skb->protocol == htons(ETH_P_RARP))) {
 120                br_do_proxy_suppress_arp(skb, br, vid, p);
 121        } else if (IS_ENABLED(CONFIG_IPV6) &&
 122                   skb->protocol == htons(ETH_P_IPV6) &&
 123                   br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
 124                   pskb_may_pull(skb, sizeof(struct ipv6hdr) +
 125                                 sizeof(struct nd_msg)) &&
 126                   ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
 127                        struct nd_msg *msg, _msg;
 128
 129                        msg = br_is_nd_neigh_msg(skb, &_msg);
 130                        if (msg)
 131                                br_do_suppress_nd(skb, br, vid, p, msg);
 132        }
 133
 134        switch (pkt_type) {
 135        case BR_PKT_MULTICAST:
 136                mdst = br_mdb_get(brmctx, skb, vid);
 137                if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
 138                    br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) {
 139                        if ((mdst && mdst->host_joined) ||
 140                            br_multicast_is_router(brmctx, skb)) {
 141                                local_rcv = true;
 142                                br->dev->stats.multicast++;
 143                        }
 144                        mcast_hit = true;
 145                } else {
 146                        local_rcv = true;
 147                        br->dev->stats.multicast++;
 148                }
 149                break;
 150        case BR_PKT_UNICAST:
 151                dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid);
 152                break;
 153        default:
 154                break;
 155        }
 156
 157        if (dst) {
 158                unsigned long now = jiffies;
 159
 160                if (test_bit(BR_FDB_LOCAL, &dst->flags))
 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, brmctx, local_rcv, false);
 171        }
 172
 173        if (local_rcv)
 174                return br_pass_frame_up(skb);
 175
 176out:
 177        return 0;
 178drop:
 179        kfree_skb(skb);
 180        goto out;
 181}
 182EXPORT_SYMBOL_GPL(br_handle_frame_finish);
 183
 184static 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            nbp_state_should_learn(p) &&
 192            !br_opt_get(p->br, BROPT_NO_LL_LEARN) &&
 193            br_should_learn(p, skb, &vid))
 194                br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0);
 195}
 196
 197/* note: already called with rcu_read_lock */
 198static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 199{
 200        __br_handle_local_finish(skb);
 201
 202        /* return 1 to signal the okfn() was called so it's ok to use the skb */
 203        return 1;
 204}
 205
 206static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb)
 207{
 208#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 209        struct nf_hook_entries *e = NULL;
 210        struct nf_hook_state state;
 211        unsigned int verdict, i;
 212        struct net *net;
 213        int ret;
 214
 215        net = dev_net(skb->dev);
 216#ifdef HAVE_JUMP_LABEL
 217        if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING]))
 218                goto frame_finish;
 219#endif
 220
 221        e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]);
 222        if (!e)
 223                goto frame_finish;
 224
 225        nf_hook_state_init(&state, NF_BR_PRE_ROUTING,
 226                           NFPROTO_BRIDGE, skb->dev, NULL, NULL,
 227                           net, br_handle_frame_finish);
 228
 229        for (i = 0; i < e->num_hook_entries; i++) {
 230                verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state);
 231                switch (verdict & NF_VERDICT_MASK) {
 232                case NF_ACCEPT:
 233                        if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) {
 234                                *pskb = skb;
 235                                return RX_HANDLER_PASS;
 236                        }
 237                        break;
 238                case NF_DROP:
 239                        kfree_skb(skb);
 240                        return RX_HANDLER_CONSUMED;
 241                case NF_QUEUE:
 242                        ret = nf_queue(skb, &state, i, verdict);
 243                        if (ret == 1)
 244                                continue;
 245                        return RX_HANDLER_CONSUMED;
 246                default: /* STOLEN */
 247                        return RX_HANDLER_CONSUMED;
 248                }
 249        }
 250frame_finish:
 251        net = dev_net(skb->dev);
 252        br_handle_frame_finish(net, NULL, skb);
 253#else
 254        br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
 255#endif
 256        return RX_HANDLER_CONSUMED;
 257}
 258
 259/* Return 0 if the frame was not processed otherwise 1
 260 * note: already called with rcu_read_lock
 261 */
 262static int br_process_frame_type(struct net_bridge_port *p,
 263                                 struct sk_buff *skb)
 264{
 265        struct br_frame_type *tmp;
 266
 267        hlist_for_each_entry_rcu(tmp, &p->br->frame_type_list, list)
 268                if (unlikely(tmp->type == skb->protocol))
 269                        return tmp->frame_handler(p, skb);
 270
 271        return 0;
 272}
 273
 274/*
 275 * Return NULL if skb is handled
 276 * note: already called with rcu_read_lock
 277 */
 278static rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 279{
 280        struct net_bridge_port *p;
 281        struct sk_buff *skb = *pskb;
 282        const unsigned char *dest = eth_hdr(skb)->h_dest;
 283
 284        if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 285                return RX_HANDLER_PASS;
 286
 287        if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 288                goto drop;
 289
 290        skb = skb_share_check(skb, GFP_ATOMIC);
 291        if (!skb)
 292                return RX_HANDLER_CONSUMED;
 293
 294        memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
 295
 296        p = br_port_get_rcu(skb->dev);
 297        if (p->flags & BR_VLAN_TUNNEL)
 298                br_handle_ingress_vlan_tunnel(skb, p, nbp_vlan_group_rcu(p));
 299
 300        if (unlikely(is_link_local_ether_addr(dest))) {
 301                u16 fwd_mask = p->br->group_fwd_mask_required;
 302
 303                /*
 304                 * See IEEE 802.1D Table 7-10 Reserved addresses
 305                 *
 306                 * Assignment                           Value
 307                 * Bridge Group Address         01-80-C2-00-00-00
 308                 * (MAC Control) 802.3          01-80-C2-00-00-01
 309                 * (Link Aggregation) 802.3     01-80-C2-00-00-02
 310                 * 802.1X PAE address           01-80-C2-00-00-03
 311                 *
 312                 * 802.1AB LLDP                 01-80-C2-00-00-0E
 313                 *
 314                 * Others reserved for future standardization
 315                 */
 316                fwd_mask |= p->group_fwd_mask;
 317                switch (dest[5]) {
 318                case 0x00:      /* Bridge Group Address */
 319                        /* If STP is turned off,
 320                           then must forward to keep loop detection */
 321                        if (p->br->stp_enabled == BR_NO_STP ||
 322                            fwd_mask & (1u << dest[5]))
 323                                goto forward;
 324                        *pskb = skb;
 325                        __br_handle_local_finish(skb);
 326                        return RX_HANDLER_PASS;
 327
 328                case 0x01:      /* IEEE MAC (Pause) */
 329                        goto drop;
 330
 331                case 0x0E:      /* 802.1AB LLDP */
 332                        fwd_mask |= p->br->group_fwd_mask;
 333                        if (fwd_mask & (1u << dest[5]))
 334                                goto forward;
 335                        *pskb = skb;
 336                        __br_handle_local_finish(skb);
 337                        return RX_HANDLER_PASS;
 338
 339                default:
 340                        /* Allow selective forwarding for most other protocols */
 341                        fwd_mask |= p->br->group_fwd_mask;
 342                        if (fwd_mask & (1u << dest[5]))
 343                                goto forward;
 344                }
 345
 346                /* The else clause should be hit when nf_hook():
 347                 *   - returns < 0 (drop/error)
 348                 *   - returns = 0 (stolen/nf_queue)
 349                 * Thus return 1 from the okfn() to signal the skb is ok to pass
 350                 */
 351                if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
 352                            dev_net(skb->dev), NULL, skb, skb->dev, NULL,
 353                            br_handle_local_finish) == 1) {
 354                        return RX_HANDLER_PASS;
 355                } else {
 356                        return RX_HANDLER_CONSUMED;
 357                }
 358        }
 359
 360        if (unlikely(br_process_frame_type(p, skb)))
 361                return RX_HANDLER_PASS;
 362
 363forward:
 364        switch (p->state) {
 365        case BR_STATE_FORWARDING:
 366        case BR_STATE_LEARNING:
 367                if (ether_addr_equal(p->br->dev->dev_addr, dest))
 368                        skb->pkt_type = PACKET_HOST;
 369
 370                return nf_hook_bridge_pre(skb, pskb);
 371        default:
 372drop:
 373                kfree_skb(skb);
 374        }
 375        return RX_HANDLER_CONSUMED;
 376}
 377
 378/* This function has no purpose other than to appease the br_port_get_rcu/rtnl
 379 * helpers which identify bridged ports according to the rx_handler installed
 380 * on them (so there _needs_ to be a bridge rx_handler even if we don't need it
 381 * to do anything useful). This bridge won't support traffic to/from the stack,
 382 * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal
 383 * frames from the ETH_P_XDSA packet_type handler.
 384 */
 385static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb)
 386{
 387        return RX_HANDLER_PASS;
 388}
 389
 390rx_handler_func_t *br_get_rx_handler(const struct net_device *dev)
 391{
 392        if (netdev_uses_dsa(dev))
 393                return br_handle_frame_dummy;
 394
 395        return br_handle_frame;
 396}
 397
 398void br_add_frame(struct net_bridge *br, struct br_frame_type *ft)
 399{
 400        hlist_add_head_rcu(&ft->list, &br->frame_type_list);
 401}
 402
 403void br_del_frame(struct net_bridge *br, struct br_frame_type *ft)
 404{
 405        struct br_frame_type *tmp;
 406
 407        hlist_for_each_entry(tmp, &br->frame_type_list, list)
 408                if (ft == tmp) {
 409                        hlist_del_rcu(&ft->list);
 410                        return;
 411                }
 412}
 413