LXR linux/net/bridge/br

   1/*
   2 *      Forwarding decision
   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/err.h>
  15#include <linux/slab.h>
  16#include <linux/kernel.h>
  17#include <linux/netdevice.h>
  18#include <linux/netpoll.h>
  19#include <linux/skbuff.h>
  20#include <linux/if_vlan.h>
  21#include <linux/netfilter_bridge.h>
  22#include "br_private.h"
  23
  24/* Don't forward packets to originating port or forwarding disabled */
  25static inline int should_deliver(const struct net_bridge_port *p,
  26                                 const struct sk_buff *skb)
  27{
  28        struct net_bridge_vlan_group *vg;
  29
  30        vg = nbp_vlan_group_rcu(p);
  31        return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
  32                br_allowed_egress(vg, skb) && p->state == BR_STATE_FORWARDING &&
  33                nbp_switchdev_allowed_egress(p, skb);
  34}
  35
  36int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
  37{
  38        if (!is_skb_forwardable(skb->dev, skb))
  39                goto drop;
  40
  41        skb_push(skb, ETH_HLEN);
  42        br_drop_fake_rtable(skb);
  43
  44        if (skb->ip_summed == CHECKSUM_PARTIAL &&
  45            (skb->protocol == htons(ETH_P_8021Q) ||
  46             skb->protocol == htons(ETH_P_8021AD))) {
  47                int depth;
  48
  49                if (!__vlan_get_protocol(skb, skb->protocol, &depth))
  50                        goto drop;
  51
  52                skb_set_network_header(skb, depth);
  53        }
  54
  55        dev_queue_xmit(skb);
  56
  57        return 0;
  58
  59drop:
  60        kfree_skb(skb);
  61        return 0;
  62}
  63EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
  64
  65int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
  66{
  67        return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING,
  68                       net, sk, skb, NULL, skb->dev,
  69                       br_dev_queue_push_xmit);
  70
  71}
  72EXPORT_SYMBOL_GPL(br_forward_finish);
  73
  74static void __br_forward(const struct net_bridge_port *to,
  75                         struct sk_buff *skb, bool local_orig)
  76{
  77        struct net_bridge_vlan_group *vg;
  78        struct net_device *indev;
  79        struct net *net;
  80        int br_hook;
  81
  82        vg = nbp_vlan_group_rcu(to);
  83        skb = br_handle_vlan(to->br, to, vg, skb);
  84        if (!skb)
  85                return;
  86
  87        indev = skb->dev;
  88        skb->dev = to->dev;
  89        if (!local_orig) {
  90                if (skb_warn_if_lro(skb)) {
  91                        kfree_skb(skb);
  92                        return;
  93                }
  94                br_hook = NF_BR_FORWARD;
  95                skb_forward_csum(skb);
  96                net = dev_net(indev);
  97        } else {
  98                if (unlikely(netpoll_tx_running(to->br->dev))) {
  99                        if (!is_skb_forwardable(skb->dev, skb)) {
 100                                kfree_skb(skb);
 101                        } else {
 102                                skb_push(skb, ETH_HLEN);
 103                                br_netpoll_send_skb(to, skb);
 104                        }
 105                        return;
 106                }
 107                br_hook = NF_BR_LOCAL_OUT;
 108                net = dev_net(skb->dev);
 109                indev = NULL;
 110        }
 111
 112        NF_HOOK(NFPROTO_BRIDGE, br_hook,
 113                net, NULL, skb, indev, skb->dev,
 114                br_forward_finish);
 115}
 116
 117static int deliver_clone(const struct net_bridge_port *prev,
 118                         struct sk_buff *skb, bool local_orig)
 119{
 120        struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 121
 122        skb = skb_clone(skb, GFP_ATOMIC);
 123        if (!skb) {
 124                dev->stats.tx_dropped++;
 125                return -ENOMEM;
 126        }
 127
 128        __br_forward(prev, skb, local_orig);
 129        return 0;
 130}
 131
 132/**
 133 * br_forward - forward a packet to a specific port
 134 * @to: destination port
 135 * @skb: packet being forwarded
 136 * @local_rcv: packet will be received locally after forwarding
 137 * @local_orig: packet is locally originated
 138 *
 139 * Should be called with rcu_read_lock.
 140 */
 141void br_forward(const struct net_bridge_port *to,
 142                struct sk_buff *skb, bool local_rcv, bool local_orig)
 143{
 144        if (to && should_deliver(to, skb)) {
 145                if (local_rcv)
 146                        deliver_clone(to, skb, local_orig);
 147                else
 148                        __br_forward(to, skb, local_orig);
 149                return;
 150        }
 151
 152        if (!local_rcv)
 153                kfree_skb(skb);
 154}
 155EXPORT_SYMBOL_GPL(br_forward);
 156
 157static struct net_bridge_port *maybe_deliver(
 158        struct net_bridge_port *prev, struct net_bridge_port *p,
 159        struct sk_buff *skb, bool local_orig)
 160{
 161        int err;
 162
 163        if (!should_deliver(p, skb))
 164                return prev;
 165
 166        if (!prev)
 167                goto out;
 168
 169        err = deliver_clone(prev, skb, local_orig);
 170        if (err)
 171                return ERR_PTR(err);
 172
 173out:
 174        return p;
 175}
 176
 177/* called under rcu_read_lock */
 178void br_flood(struct net_bridge *br, struct sk_buff *skb,
 179              enum br_pkt_type pkt_type, bool local_rcv, bool local_orig)
 180{
 181        u8 igmp_type = br_multicast_igmp_type(skb);
 182        struct net_bridge_port *prev = NULL;
 183        struct net_bridge_port *p;
 184
 185        list_for_each_entry_rcu(p, &br->port_list, list) {
 186                /* Do not flood unicast traffic to ports that turn it off, nor
 187                 * other traffic if flood off, except for traffic we originate
 188                 */
 189                switch (pkt_type) {
 190                case BR_PKT_UNICAST:
 191                        if (!(p->flags & BR_FLOOD))
 192                                continue;
 193                        break;
 194                case BR_PKT_MULTICAST:
 195                        if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
 196                                continue;
 197                        break;
 198                case BR_PKT_BROADCAST:
 199                        if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
 200                                continue;
 201                        break;
 202                }
 203
 204                /* Do not flood to ports that enable proxy ARP */
 205                if (p->flags & BR_PROXYARP)
 206                        continue;
 207                if ((p->flags & BR_PROXYARP_WIFI) &&
 208                    BR_INPUT_SKB_CB(skb)->proxyarp_replied)
 209                        continue;
 210
 211                prev = maybe_deliver(prev, p, skb, local_orig);
 212                if (IS_ERR(prev))
 213                        goto out;
 214                if (prev == p)
 215                        br_multicast_count(p->br, p, skb, igmp_type,
 216                                           BR_MCAST_DIR_TX);
 217        }
 218
 219        if (!prev)
 220                goto out;
 221
 222        if (local_rcv)
 223                deliver_clone(prev, skb, local_orig);
 224        else
 225                __br_forward(prev, skb, local_orig);
 226        return;
 227
 228out:
 229        if (!local_rcv)
 230                kfree_skb(skb);
 231}
 232
 233#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 234static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb,
 235                               const unsigned char *addr, bool local_orig)
 236{
 237        struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 238        const unsigned char *src = eth_hdr(skb)->h_source;
 239
 240        if (!should_deliver(p, skb))
 241                return;
 242
 243        /* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */
 244        if (skb->dev == p->dev && ether_addr_equal(src, addr))
 245                return;
 246
 247        skb = skb_copy(skb, GFP_ATOMIC);
 248        if (!skb) {
 249                dev->stats.tx_dropped++;
 250                return;
 251        }
 252
 253        if (!is_broadcast_ether_addr(addr))
 254                memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);
 255
 256        __br_forward(p, skb, local_orig);
 257}
 258
 259/* called with rcu_read_lock */
 260void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 261                        struct sk_buff *skb,
 262                        bool local_rcv, bool local_orig)
 263{
 264        struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 265        u8 igmp_type = br_multicast_igmp_type(skb);
 266        struct net_bridge *br = netdev_priv(dev);
 267        struct net_bridge_port *prev = NULL;
 268        struct net_bridge_port_group *p;
 269        struct hlist_node *rp;
 270
 271        rp = rcu_dereference(hlist_first_rcu(&br->router_list));
 272        p = mdst ? rcu_dereference(mdst->ports) : NULL;
 273        while (p || rp) {
 274                struct net_bridge_port *port, *lport, *rport;
 275
 276                lport = p ? p->port : NULL;
 277                rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
 278                             NULL;
 279
 280                if ((unsigned long)lport > (unsigned long)rport) {
 281                        port = lport;
 282
 283                        if (port->flags & BR_MULTICAST_TO_UNICAST) {
 284                                maybe_deliver_addr(lport, skb, p->eth_addr,
 285                                                   local_orig);
 286                                goto delivered;
 287                        }
 288                } else {
 289                        port = rport;
 290                }
 291
 292                prev = maybe_deliver(prev, port, skb, local_orig);
 293delivered:
 294                if (IS_ERR(prev))
 295                        goto out;
 296                if (prev == port)
 297                        br_multicast_count(port->br, port, skb, igmp_type,
 298                                           BR_MCAST_DIR_TX);
 299
 300                if ((unsigned long)lport >= (unsigned long)port)
 301                        p = rcu_dereference(p->next);
 302                if ((unsigned long)rport >= (unsigned long)port)
 303                        rp = rcu_dereference(hlist_next_rcu(rp));
 304        }
 305
 306        if (!prev)
 307                goto out;
 308
 309        if (local_rcv)
 310                deliver_clone(prev, skb, local_orig);
 311        else
 312                __br_forward(prev, skb, local_orig);
 313        return;
 314
 315out:
 316        if (!local_rcv)
 317                kfree_skb(skb);
 318}
 319#endif
 320