net/bridge/br_forward.c

   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 */
  25 static 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                 !br_skb_isolated(p, skb);
  35 }
  36
  37 int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
  38 {
  39         skb_push(skb, ETH_HLEN);
  40         if (!is_skb_forwardable(skb->dev, skb))
  41                 goto drop;
  42
  43         br_drop_fake_rtable(skb);
  44
  45         if (skb->ip_summed == CHECKSUM_PARTIAL &&
  46             (skb->protocol == htons(ETH_P_8021Q) ||
  47              skb->protocol == htons(ETH_P_8021AD))) {
  48                 int depth;
  49
  50                 if (!__vlan_get_protocol(skb, skb->protocol, &depth))
  51                         goto drop;
  52
  53                 skb_set_network_header(skb, depth);
  54         }
  55
  56         dev_queue_xmit(skb);
  57
  58         return 0;
  59
  60 drop:
  61         kfree_skb(skb);
  62         return 0;
  63 }
  64 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
  65
  66 int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
  67 {
  68         skb->tstamp = 0;
  69         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING,
  70                        net, sk, skb, NULL, skb->dev,
  71                        br_dev_queue_push_xmit);
  72
  73 }
  74 EXPORT_SYMBOL_GPL(br_forward_finish);
  75
  76 static void __br_forward(const struct net_bridge_port *to,
  77                          struct sk_buff *skb, bool local_orig)
  78 {
  79         struct net_bridge_vlan_group *vg;
  80         struct net_device *indev;
  81         struct net *net;
  82         int br_hook;
  83
  84         vg = nbp_vlan_group_rcu(to);
  85         skb = br_handle_vlan(to->br, to, vg, skb);
  86         if (!skb)
  87                 return;
  88
  89         indev = skb->dev;
  90         skb->dev = to->dev;
  91         if (!local_orig) {
  92                 if (skb_warn_if_lro(skb)) {
  93                         kfree_skb(skb);
  94                         return;
  95                 }
  96                 br_hook = NF_BR_FORWARD;
  97                 skb_forward_csum(skb);
  98                 net = dev_net(indev);
  99         } else {
 100                 if (unlikely(netpoll_tx_running(to->br->dev))) {
 101                         skb_push(skb, ETH_HLEN);
 102                         if (!is_skb_forwardable(skb->dev, skb))
 103                                 kfree_skb(skb);
 104                         else
 105                                 br_netpoll_send_skb(to, skb);
 106                         return;
 107                 }
 108                 br_hook = NF_BR_LOCAL_OUT;
 109                 net = dev_net(skb->dev);
 110                 indev = NULL;
 111         }
 112
 113         NF_HOOK(NFPROTO_BRIDGE, br_hook,
 114                 net, NULL, skb, indev, skb->dev,
 115                 br_forward_finish);
 116 }
 117
 118 static int deliver_clone(const struct net_bridge_port *prev,
 119                          struct sk_buff *skb, bool local_orig)
 120 {
 121         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 122
 123         skb = skb_clone(skb, GFP_ATOMIC);
 124         if (!skb) {
 125                 dev->stats.tx_dropped++;
 126                 return -ENOMEM;
 127         }
 128
 129         __br_forward(prev, skb, local_orig);
 130         return 0;
 131 }
 132
 133 /**
 134  * br_forward - forward a packet to a specific port
 135  * @to: destination port
 136  * @skb: packet being forwarded
 137  * @local_rcv: packet will be received locally after forwarding
 138  * @local_orig: packet is locally originated
 139  *
 140  * Should be called with rcu_read_lock.
 141  */
 142 void br_forward(const struct net_bridge_port *to,
 143                 struct sk_buff *skb, bool local_rcv, bool local_orig)
 144 {
 145         if (unlikely(!to))
 146                 goto out;
 147
 148         /* redirect to backup link if the destination port is down */
 149         if (rcu_access_pointer(to->backup_port) && !netif_carrier_ok(to->dev)) {
 150                 struct net_bridge_port *backup_port;
 151
 152                 backup_port = rcu_dereference(to->backup_port);
 153                 if (unlikely(!backup_port))
 154                         goto out;
 155                 to = backup_port;
 156         }
 157
 158         if (should_deliver(to, skb)) {
 159                 if (local_rcv)
 160                         deliver_clone(to, skb, local_orig);
 161                 else
 162                         __br_forward(to, skb, local_orig);
 163                 return;
 164         }
 165
 166 out:
 167         if (!local_rcv)
 168                 kfree_skb(skb);
 169 }
 170 EXPORT_SYMBOL_GPL(br_forward);
 171
 172 static struct net_bridge_port *maybe_deliver(
 173         struct net_bridge_port *prev, struct net_bridge_port *p,
 174         struct sk_buff *skb, bool local_orig)
 175 {
 176         u8 igmp_type = br_multicast_igmp_type(skb);
 177         int err;
 178
 179         if (!should_deliver(p, skb))
 180                 return prev;
 181
 182         if (!prev)
 183                 goto out;
 184
 185         err = deliver_clone(prev, skb, local_orig);
 186         if (err)
 187                 return ERR_PTR(err);
 188 out:
 189         br_multicast_count(p->br, p, skb, igmp_type, BR_MCAST_DIR_TX);
 190
 191         return p;
 192 }
 193
 194 /* called under rcu_read_lock */
 195 void br_flood(struct net_bridge *br, struct sk_buff *skb,
 196               enum br_pkt_type pkt_type, bool local_rcv, bool local_orig)
 197 {
 198         struct net_bridge_port *prev = NULL;
 199         struct net_bridge_port *p;
 200
 201         list_for_each_entry_rcu(p, &br->port_list, list) {
 202                 /* Do not flood unicast traffic to ports that turn it off, nor
 203                  * other traffic if flood off, except for traffic we originate
 204                  */
 205                 switch (pkt_type) {
 206                 case BR_PKT_UNICAST:
 207                         if (!(p->flags & BR_FLOOD))
 208                                 continue;
 209                         break;
 210                 case BR_PKT_MULTICAST:
 211                         if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
 212                                 continue;
 213                         break;
 214                 case BR_PKT_BROADCAST:
 215                         if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
 216                                 continue;
 217                         break;
 218                 }
 219
 220                 /* Do not flood to ports that enable proxy ARP */
 221                 if (p->flags & BR_PROXYARP)
 222                         continue;
 223                 if ((p->flags & (BR_PROXYARP_WIFI | BR_NEIGH_SUPPRESS)) &&
 224                     BR_INPUT_SKB_CB(skb)->proxyarp_replied)
 225                         continue;
 226
 227                 prev = maybe_deliver(prev, p, skb, local_orig);
 228                 if (IS_ERR(prev))
 229                         goto out;
 230         }
 231
 232         if (!prev)
 233                 goto out;
 234
 235         if (local_rcv)
 236                 deliver_clone(prev, skb, local_orig);
 237         else
 238                 __br_forward(prev, skb, local_orig);
 239         return;
 240
 241 out:
 242         if (!local_rcv)
 243                 kfree_skb(skb);
 244 }
 245
 246 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 247 static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb,
 248                                const unsigned char *addr, bool local_orig)
 249 {
 250         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 251         const unsigned char *src = eth_hdr(skb)->h_source;
 252
 253         if (!should_deliver(p, skb))
 254                 return;
 255
 256         /* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */
 257         if (skb->dev == p->dev && ether_addr_equal(src, addr))
 258                 return;
 259
 260         skb = skb_copy(skb, GFP_ATOMIC);
 261         if (!skb) {
 262                 dev->stats.tx_dropped++;
 263                 return;
 264         }
 265
 266         if (!is_broadcast_ether_addr(addr))
 267                 memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);
 268
 269         __br_forward(p, skb, local_orig);
 270 }
 271
 272 /* called with rcu_read_lock */
 273 void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 274                         struct sk_buff *skb,
 275                         bool local_rcv, bool local_orig)
 276 {
 277         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 278         struct net_bridge *br = netdev_priv(dev);
 279         struct net_bridge_port *prev = NULL;
 280         struct net_bridge_port_group *p;
 281         struct hlist_node *rp;
 282
 283         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
 284         p = mdst ? rcu_dereference(mdst->ports) : NULL;
 285         while (p || rp) {
 286                 struct net_bridge_port *port, *lport, *rport;
 287
 288                 lport = p ? p->port : NULL;
 289                 rport = hlist_entry_safe(rp, struct net_bridge_port, rlist);
 290
 291                 if ((unsigned long)lport > (unsigned long)rport) {
 292                         port = lport;
 293
 294                         if (port->flags & BR_MULTICAST_TO_UNICAST) {
 295                                 maybe_deliver_addr(lport, skb, p->eth_addr,
 296                                                    local_orig);
 297                                 goto delivered;
 298                         }
 299                 } else {
 300                         port = rport;
 301                 }
 302
 303                 prev = maybe_deliver(prev, port, skb, local_orig);
 304                 if (IS_ERR(prev))
 305                         goto out;
 306 delivered:
 307                 if ((unsigned long)lport >= (unsigned long)port)
 308                         p = rcu_dereference(p->next);
 309                 if ((unsigned long)rport >= (unsigned long)port)
 310                         rp = rcu_dereference(hlist_next_rcu(rp));
 311         }
 312
 313         if (!prev)
 314                 goto out;
 315
 316         if (local_rcv)
 317                 deliver_clone(prev, skb, local_orig);
 318         else
 319                 __br_forward(prev, skb, local_orig);
 320         return;
 321
 322 out:
 323         if (!local_rcv)
 324                 kfree_skb(skb);
 325 }
 326 #endif