net/bridge/br_forward.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      Forwarding decision
   4  *      Linux ethernet bridge
   5  *
   6  *      Authors:
   7  *      Lennert Buytenhek               <buytenh@gnu.org>
   8  */
   9
  10 #include <linux/err.h>
  11 #include <linux/slab.h>
  12 #include <linux/kernel.h>
  13 #include <linux/netdevice.h>
  14 #include <linux/netpoll.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/if_vlan.h>
  17 #include <linux/netfilter_bridge.h>
  18 #include "br_private.h"
  19
  20 /* Don't forward packets to originating port or forwarding disabled */
  21 static inline int should_deliver(const struct net_bridge_port *p,
  22                                  const struct sk_buff *skb)
  23 {
  24         struct net_bridge_vlan_group *vg;
  25
  26         vg = nbp_vlan_group_rcu(p);
  27         return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
  28                 p->state == BR_STATE_FORWARDING && br_allowed_egress(vg, skb) &&
  29                 nbp_switchdev_allowed_egress(p, skb) &&
  30                 !br_skb_isolated(p, skb);
  31 }
  32
  33 int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
  34 {
  35         skb_push(skb, ETH_HLEN);
  36         if (!is_skb_forwardable(skb->dev, skb))
  37                 goto drop;
  38
  39         br_drop_fake_rtable(skb);
  40
  41         if (skb->ip_summed == CHECKSUM_PARTIAL &&
  42             eth_type_vlan(skb->protocol)) {
  43                 int depth;
  44
  45                 if (!__vlan_get_protocol(skb, skb->protocol, &depth))
  46                         goto drop;
  47
  48                 skb_set_network_header(skb, depth);
  49         }
  50
  51         dev_queue_xmit(skb);
  52
  53         return 0;
  54
  55 drop:
  56         kfree_skb(skb);
  57         return 0;
  58 }
  59 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
  60
  61 int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
  62 {
  63         skb->tstamp = 0;
  64         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING,
  65                        net, sk, skb, NULL, skb->dev,
  66                        br_dev_queue_push_xmit);
  67
  68 }
  69 EXPORT_SYMBOL_GPL(br_forward_finish);
  70
  71 static void __br_forward(const struct net_bridge_port *to,
  72                          struct sk_buff *skb, bool local_orig)
  73 {
  74         struct net_bridge_vlan_group *vg;
  75         struct net_device *indev;
  76         struct net *net;
  77         int br_hook;
  78
  79         vg = nbp_vlan_group_rcu(to);
  80         skb = br_handle_vlan(to->br, to, vg, skb);
  81         if (!skb)
  82                 return;
  83
  84         indev = skb->dev;
  85         skb->dev = to->dev;
  86         if (!local_orig) {
  87                 if (skb_warn_if_lro(skb)) {
  88                         kfree_skb(skb);
  89                         return;
  90                 }
  91                 br_hook = NF_BR_FORWARD;
  92                 skb_forward_csum(skb);
  93                 net = dev_net(indev);
  94         } else {
  95                 if (unlikely(netpoll_tx_running(to->br->dev))) {
  96                         skb_push(skb, ETH_HLEN);
  97                         if (!is_skb_forwardable(skb->dev, skb))
  98                                 kfree_skb(skb);
  99                         else
 100                                 br_netpoll_send_skb(to, skb);
 101                         return;
 102                 }
 103                 br_hook = NF_BR_LOCAL_OUT;
 104                 net = dev_net(skb->dev);
 105                 indev = NULL;
 106         }
 107
 108         NF_HOOK(NFPROTO_BRIDGE, br_hook,
 109                 net, NULL, skb, indev, skb->dev,
 110                 br_forward_finish);
 111 }
 112
 113 static int deliver_clone(const struct net_bridge_port *prev,
 114                          struct sk_buff *skb, bool local_orig)
 115 {
 116         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 117
 118         skb = skb_clone(skb, GFP_ATOMIC);
 119         if (!skb) {
 120                 dev->stats.tx_dropped++;
 121                 return -ENOMEM;
 122         }
 123
 124         __br_forward(prev, skb, local_orig);
 125         return 0;
 126 }
 127
 128 /**
 129  * br_forward - forward a packet to a specific port
 130  * @to: destination port
 131  * @skb: packet being forwarded
 132  * @local_rcv: packet will be received locally after forwarding
 133  * @local_orig: packet is locally originated
 134  *
 135  * Should be called with rcu_read_lock.
 136  */
 137 void br_forward(const struct net_bridge_port *to,
 138                 struct sk_buff *skb, bool local_rcv, bool local_orig)
 139 {
 140         if (unlikely(!to))
 141                 goto out;
 142
 143         /* redirect to backup link if the destination port is down */
 144         if (rcu_access_pointer(to->backup_port) && !netif_carrier_ok(to->dev)) {
 145                 struct net_bridge_port *backup_port;
 146
 147                 backup_port = rcu_dereference(to->backup_port);
 148                 if (unlikely(!backup_port))
 149                         goto out;
 150                 to = backup_port;
 151         }
 152
 153         if (should_deliver(to, skb)) {
 154                 if (local_rcv)
 155                         deliver_clone(to, skb, local_orig);
 156                 else
 157                         __br_forward(to, skb, local_orig);
 158                 return;
 159         }
 160
 161 out:
 162         if (!local_rcv)
 163                 kfree_skb(skb);
 164 }
 165 EXPORT_SYMBOL_GPL(br_forward);
 166
 167 static struct net_bridge_port *maybe_deliver(
 168         struct net_bridge_port *prev, struct net_bridge_port *p,
 169         struct sk_buff *skb, bool local_orig)
 170 {
 171         u8 igmp_type = br_multicast_igmp_type(skb);
 172         int err;
 173
 174         if (!should_deliver(p, skb))
 175                 return prev;
 176
 177         if (!prev)
 178                 goto out;
 179
 180         err = deliver_clone(prev, skb, local_orig);
 181         if (err)
 182                 return ERR_PTR(err);
 183 out:
 184         br_multicast_count(p->br, p, skb, igmp_type, BR_MCAST_DIR_TX);
 185
 186         return p;
 187 }
 188
 189 /* called under rcu_read_lock */
 190 void br_flood(struct net_bridge *br, struct sk_buff *skb,
 191               enum br_pkt_type pkt_type, bool local_rcv, bool local_orig)
 192 {
 193         struct net_bridge_port *prev = NULL;
 194         struct net_bridge_port *p;
 195
 196         list_for_each_entry_rcu(p, &br->port_list, list) {
 197                 /* Do not flood unicast traffic to ports that turn it off, nor
 198                  * other traffic if flood off, except for traffic we originate
 199                  */
 200                 switch (pkt_type) {
 201                 case BR_PKT_UNICAST:
 202                         if (!(p->flags & BR_FLOOD))
 203                                 continue;
 204                         break;
 205                 case BR_PKT_MULTICAST:
 206                         if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
 207                                 continue;
 208                         break;
 209                 case BR_PKT_BROADCAST:
 210                         if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
 211                                 continue;
 212                         break;
 213                 }
 214
 215                 /* Do not flood to ports that enable proxy ARP */
 216                 if (p->flags & BR_PROXYARP)
 217                         continue;
 218                 if ((p->flags & (BR_PROXYARP_WIFI | BR_NEIGH_SUPPRESS)) &&
 219                     BR_INPUT_SKB_CB(skb)->proxyarp_replied)
 220                         continue;
 221
 222                 prev = maybe_deliver(prev, p, skb, local_orig);
 223                 if (IS_ERR(prev))
 224                         goto out;
 225         }
 226
 227         if (!prev)
 228                 goto out;
 229
 230         if (local_rcv)
 231                 deliver_clone(prev, skb, local_orig);
 232         else
 233                 __br_forward(prev, skb, local_orig);
 234         return;
 235
 236 out:
 237         if (!local_rcv)
 238                 kfree_skb(skb);
 239 }
 240
 241 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 242 static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb,
 243                                const unsigned char *addr, bool local_orig)
 244 {
 245         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 246         const unsigned char *src = eth_hdr(skb)->h_source;
 247
 248         if (!should_deliver(p, skb))
 249                 return;
 250
 251         /* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */
 252         if (skb->dev == p->dev && ether_addr_equal(src, addr))
 253                 return;
 254
 255         skb = skb_copy(skb, GFP_ATOMIC);
 256         if (!skb) {
 257                 dev->stats.tx_dropped++;
 258                 return;
 259         }
 260
 261         if (!is_broadcast_ether_addr(addr))
 262                 memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);
 263
 264         __br_forward(p, skb, local_orig);
 265 }
 266
 267 /* called with rcu_read_lock */
 268 void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 269                         struct sk_buff *skb,
 270                         bool local_rcv, bool local_orig)
 271 {
 272         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 273         struct net_bridge *br = netdev_priv(dev);
 274         struct net_bridge_port *prev = NULL;
 275         struct net_bridge_port_group *p;
 276         bool allow_mode_include = true;
 277         struct hlist_node *rp;
 278
 279         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
 280         if (mdst) {
 281                 p = rcu_dereference(mdst->ports);
 282                 if (br_multicast_should_handle_mode(br, mdst->addr.proto) &&
 283                     br_multicast_is_star_g(&mdst->addr))
 284                         allow_mode_include = false;
 285         } else {
 286                 p = NULL;
 287         }
 288
 289         while (p || rp) {
 290                 struct net_bridge_port *port, *lport, *rport;
 291
 292                 lport = p ? p->key.port : NULL;
 293                 rport = hlist_entry_safe(rp, struct net_bridge_port, rlist);
 294
 295                 if ((unsigned long)lport > (unsigned long)rport) {
 296                         port = lport;
 297
 298                         if (port->flags & BR_MULTICAST_TO_UNICAST) {
 299                                 maybe_deliver_addr(lport, skb, p->eth_addr,
 300                                                    local_orig);
 301                                 goto delivered;
 302                         }
 303                         if ((!allow_mode_include &&
 304                              p->filter_mode == MCAST_INCLUDE) ||
 305                             (p->flags & MDB_PG_FLAGS_BLOCKED))
 306                                 goto delivered;
 307                 } else {
 308                         port = rport;
 309                 }
 310
 311                 prev = maybe_deliver(prev, port, skb, local_orig);
 312                 if (IS_ERR(prev))
 313                         goto out;
 314 delivered:
 315                 if ((unsigned long)lport >= (unsigned long)port)
 316                         p = rcu_dereference(p->next);
 317                 if ((unsigned long)rport >= (unsigned long)port)
 318                         rp = rcu_dereference(hlist_next_rcu(rp));
 319         }
 320
 321         if (!prev)
 322                 goto out;
 323
 324         if (local_rcv)
 325                 deliver_clone(prev, skb, local_orig);
 326         else
 327                 __br_forward(prev, skb, local_orig);
 328         return;
 329
 330 out:
 331         if (!local_rcv)
 332                 kfree_skb(skb);
 333 }
 334 #endif