LXR linux/net/bridge/br

   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 */
  26br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
  27EXPORT_SYMBOL(br_should_route_hook);
  28
  29static int br_pass_frame_up(struct sk_buff *skb)
  30{
  31        struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
  32        struct net_bridge *br = netdev_priv(brdev);
  33        struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
  34        struct net_port_vlans *pv;
  35
  36        u64_stats_update_begin(&brstats->syncp);
  37        brstats->rx_packets++;
  38        brstats->rx_bytes += skb->len;
  39        u64_stats_update_end(&brstats->syncp);
  40
  41        /* Bridge is just like any other port.  Make sure the
  42         * packet is allowed except in promisc modue when someone
  43         * may be running packet capture.
  44         */
  45        pv = br_get_vlan_info(br);
  46        if (!(brdev->flags & IFF_PROMISC) &&
  47            !br_allowed_egress(br, pv, 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, pv, skb);
  55        if (!skb)
  56                return NET_RX_DROP;
  57
  58        return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, NULL, skb,
  59                       indev, NULL,
  60                       netif_receive_skb_sk);
  61}
  62
  63static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
  64                            u16 vid, struct net_bridge_port *p)
  65{
  66        struct net_device *dev = br->dev;
  67        struct neighbour *n;
  68        struct arphdr *parp;
  69        u8 *arpptr, *sha;
  70        __be32 sip, tip;
  71
  72        BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
  73
  74        if (dev->flags & IFF_NOARP)
  75                return;
  76
  77        if (!pskb_may_pull(skb, arp_hdr_len(dev))) {
  78                dev->stats.tx_dropped++;
  79                return;
  80        }
  81        parp = arp_hdr(skb);
  82
  83        if (parp->ar_pro != htons(ETH_P_IP) ||
  84            parp->ar_op != htons(ARPOP_REQUEST) ||
  85            parp->ar_hln != dev->addr_len ||
  86            parp->ar_pln != 4)
  87                return;
  88
  89        arpptr = (u8 *)parp + sizeof(struct arphdr);
  90        sha = arpptr;
  91        arpptr += dev->addr_len;        /* sha */
  92        memcpy(&sip, arpptr, sizeof(sip));
  93        arpptr += sizeof(sip);
  94        arpptr += dev->addr_len;        /* tha */
  95        memcpy(&tip, arpptr, sizeof(tip));
  96
  97        if (ipv4_is_loopback(tip) ||
  98            ipv4_is_multicast(tip))
  99                return;
 100
 101        n = neigh_lookup(&arp_tbl, &tip, dev);
 102        if (n) {
 103                struct net_bridge_fdb_entry *f;
 104
 105                if (!(n->nud_state & NUD_VALID)) {
 106                        neigh_release(n);
 107                        return;
 108                }
 109
 110                f = __br_fdb_get(br, n->ha, vid);
 111                if (f && ((p->flags & BR_PROXYARP) ||
 112                          (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) {
 113                        arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip,
 114                                 sha, n->ha, sha);
 115                        BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
 116                }
 117
 118                neigh_release(n);
 119        }
 120}
 121
 122/* note: already called with rcu_read_lock */
 123int br_handle_frame_finish(struct sock *sk, struct sk_buff *skb)
 124{
 125        const unsigned char *dest = eth_hdr(skb)->h_dest;
 126        struct net_bridge_port *p = br_port_get_rcu(skb->dev);
 127        struct net_bridge *br;
 128        struct net_bridge_fdb_entry *dst;
 129        struct net_bridge_mdb_entry *mdst;
 130        struct sk_buff *skb2;
 131        bool unicast = true;
 132        u16 vid = 0;
 133
 134        if (!p || p->state == BR_STATE_DISABLED)
 135                goto drop;
 136
 137        if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb, &vid))
 138                goto out;
 139
 140        /* insert into forwarding database after filtering to avoid spoofing */
 141        br = p->br;
 142        if (p->flags & BR_LEARNING)
 143                br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);
 144
 145        if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
 146            br_multicast_rcv(br, p, skb, vid))
 147                goto drop;
 148
 149        if (p->state == BR_STATE_LEARNING)
 150                goto drop;
 151
 152        BR_INPUT_SKB_CB(skb)->brdev = br->dev;
 153
 154        /* The packet skb2 goes to the local host (NULL to skip). */
 155        skb2 = NULL;
 156
 157        if (br->dev->flags & IFF_PROMISC)
 158                skb2 = skb;
 159
 160        dst = NULL;
 161
 162        if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP))
 163                br_do_proxy_arp(skb, br, vid, p);
 164
 165        if (is_broadcast_ether_addr(dest)) {
 166                skb2 = skb;
 167                unicast = false;
 168        } else if (is_multicast_ether_addr(dest)) {
 169                mdst = br_mdb_get(br, skb, vid);
 170                if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
 171                    br_multicast_querier_exists(br, eth_hdr(skb))) {
 172                        if ((mdst && mdst->mglist) ||
 173                            br_multicast_is_router(br))
 174                                skb2 = skb;
 175                        br_multicast_forward(mdst, skb, skb2);
 176                        skb = NULL;
 177                        if (!skb2)
 178                                goto out;
 179                } else
 180                        skb2 = skb;
 181
 182                unicast = false;
 183                br->dev->stats.multicast++;
 184        } else if ((dst = __br_fdb_get(br, dest, vid)) &&
 185                        dst->is_local) {
 186                skb2 = skb;
 187                /* Do not forward the packet since it's local. */
 188                skb = NULL;
 189        }
 190
 191        if (skb) {
 192                if (dst) {
 193                        dst->used = jiffies;
 194                        br_forward(dst->dst, skb, skb2);
 195                } else
 196                        br_flood_forward(br, skb, skb2, unicast);
 197        }
 198
 199        if (skb2)
 200                return br_pass_frame_up(skb2);
 201
 202out:
 203        return 0;
 204drop:
 205        kfree_skb(skb);
 206        goto out;
 207}
 208EXPORT_SYMBOL_GPL(br_handle_frame_finish);
 209
 210/* note: already called with rcu_read_lock */
 211static int br_handle_local_finish(struct sock *sk, 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        return 0;        /* process further */
 220}
 221
 222/*
 223 * Return NULL if skb is handled
 224 * note: already called with rcu_read_lock
 225 */
 226rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 227{
 228        struct net_bridge_port *p;
 229        struct sk_buff *skb = *pskb;
 230        const unsigned char *dest = eth_hdr(skb)->h_dest;
 231        br_should_route_hook_t *rhook;
 232
 233        if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 234                return RX_HANDLER_PASS;
 235
 236        if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
 237                goto drop;
 238
 239        skb = skb_share_check(skb, GFP_ATOMIC);
 240        if (!skb)
 241                return RX_HANDLER_CONSUMED;
 242
 243        p = br_port_get_rcu(skb->dev);
 244
 245        if (unlikely(is_link_local_ether_addr(dest))) {
 246                u16 fwd_mask = p->br->group_fwd_mask_required;
 247
 248                /*
 249                 * See IEEE 802.1D Table 7-10 Reserved addresses
 250                 *
 251                 * Assignment                           Value
 252                 * Bridge Group Address         01-80-C2-00-00-00
 253                 * (MAC Control) 802.3          01-80-C2-00-00-01
 254                 * (Link Aggregation) 802.3     01-80-C2-00-00-02
 255                 * 802.1X PAE address           01-80-C2-00-00-03
 256                 *
 257                 * 802.1AB LLDP                 01-80-C2-00-00-0E
 258                 *
 259                 * Others reserved for future standardization
 260                 */
 261                switch (dest[5]) {
 262                case 0x00:      /* Bridge Group Address */
 263                        /* If STP is turned off,
 264                           then must forward to keep loop detection */
 265                        if (p->br->stp_enabled == BR_NO_STP ||
 266                            fwd_mask & (1u << dest[5]))
 267                                goto forward;
 268                        break;
 269
 270                case 0x01:      /* IEEE MAC (Pause) */
 271                        goto drop;
 272
 273                default:
 274                        /* Allow selective forwarding for most other protocols */
 275                        fwd_mask |= p->br->group_fwd_mask;
 276                        if (fwd_mask & (1u << dest[5]))
 277                                goto forward;
 278                }
 279
 280                /* Deliver packet to local host only */
 281                if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, NULL, skb,
 282                            skb->dev, NULL, br_handle_local_finish)) {
 283                        return RX_HANDLER_CONSUMED; /* consumed by filter */
 284                } else {
 285                        *pskb = skb;
 286                        return RX_HANDLER_PASS; /* continue processing */
 287                }
 288        }
 289
 290forward:
 291        switch (p->state) {
 292        case BR_STATE_FORWARDING:
 293                rhook = rcu_dereference(br_should_route_hook);
 294                if (rhook) {
 295                        if ((*rhook)(skb)) {
 296                                *pskb = skb;
 297                                return RX_HANDLER_PASS;
 298                        }
 299                        dest = eth_hdr(skb)->h_dest;
 300                }
 301                /* fall through */
 302        case BR_STATE_LEARNING:
 303                if (ether_addr_equal(p->br->dev->dev_addr, dest))
 304                        skb->pkt_type = PACKET_HOST;
 305
 306                NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, NULL, skb,
 307                        skb->dev, NULL,
 308                        br_handle_frame_finish);
 309                break;
 310        default:
 311drop:
 312                kfree_skb(skb);
 313        }
 314        return RX_HANDLER_CONSUMED;
 315}
 316