net/bridge/br_forward.c

   1 /*
   2  *      Forwarding decision
   3  *      Linux ethernet bridge
   4  *
   5  *      Authors:
   6  *      Lennert Buytenhek               <[email protected]>
   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 }
  35
  36 int 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
  59 drop:
  60         kfree_skb(skb);
  61         return 0;
  62 }
  63 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
  64
  65 int 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 }
  72 EXPORT_SYMBOL_GPL(br_forward_finish);
  73
  74 static 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
 117 static 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  */
 141 void 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 }
 155 EXPORT_SYMBOL_GPL(br_forward);
 156
 157 static 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
 173 out:
 174         return p;
 175 }
 176
 177 /* called under rcu_read_lock */
 178 void 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 */
 187                 if (pkt_type == BR_PKT_UNICAST && !(p->flags & BR_FLOOD))
 188                         continue;
 189                 /* Do not flood if mc off, except for traffic we originate */
 190                 if (pkt_type == BR_PKT_MULTICAST &&
 191                     !(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
 192                         continue;
 193
 194                 /* Do not flood to ports that enable proxy ARP */
 195                 if (p->flags & BR_PROXYARP)
 196                         continue;
 197                 if ((p->flags & BR_PROXYARP_WIFI) &&
 198                     BR_INPUT_SKB_CB(skb)->proxyarp_replied)
 199                         continue;
 200
 201                 prev = maybe_deliver(prev, p, skb, local_orig);
 202                 if (IS_ERR(prev))
 203                         goto out;
 204                 if (prev == p)
 205                         br_multicast_count(p->br, p, skb, igmp_type,
 206                                            BR_MCAST_DIR_TX);
 207         }
 208
 209         if (!prev)
 210                 goto out;
 211
 212         if (local_rcv)
 213                 deliver_clone(prev, skb, local_orig);
 214         else
 215                 __br_forward(prev, skb, local_orig);
 216         return;
 217
 218 out:
 219         if (!local_rcv)
 220                 kfree_skb(skb);
 221 }
 222
 223 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 224 static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb,
 225                                const unsigned char *addr, bool local_orig)
 226 {
 227         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 228         const unsigned char *src = eth_hdr(skb)->h_source;
 229
 230         if (!should_deliver(p, skb))
 231                 return;
 232
 233         /* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */
 234         if (skb->dev == p->dev && ether_addr_equal(src, addr))
 235                 return;
 236
 237         skb = skb_copy(skb, GFP_ATOMIC);
 238         if (!skb) {
 239                 dev->stats.tx_dropped++;
 240                 return;
 241         }
 242
 243         if (!is_broadcast_ether_addr(addr))
 244                 memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);
 245
 246         __br_forward(p, skb, local_orig);
 247 }
 248
 249 /* called with rcu_read_lock */
 250 void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 251                         struct sk_buff *skb,
 252                         bool local_rcv, bool local_orig)
 253 {
 254         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 255         u8 igmp_type = br_multicast_igmp_type(skb);
 256         struct net_bridge *br = netdev_priv(dev);
 257         struct net_bridge_port *prev = NULL;
 258         struct net_bridge_port_group *p;
 259         struct hlist_node *rp;
 260
 261         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
 262         p = mdst ? rcu_dereference(mdst->ports) : NULL;
 263         while (p || rp) {
 264                 struct net_bridge_port *port, *lport, *rport;
 265
 266                 lport = p ? p->port : NULL;
 267                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
 268                              NULL;
 269
 270                 if ((unsigned long)lport > (unsigned long)rport) {
 271                         port = lport;
 272
 273                         if (port->flags & BR_MULTICAST_TO_UNICAST) {
 274                                 maybe_deliver_addr(lport, skb, p->eth_addr,
 275                                                    local_orig);
 276                                 goto delivered;
 277                         }
 278                 } else {
 279                         port = rport;
 280                 }
 281
 282                 prev = maybe_deliver(prev, port, skb, local_orig);
 283 delivered:
 284                 if (IS_ERR(prev))
 285                         goto out;
 286                 if (prev == port)
 287                         br_multicast_count(port->br, port, skb, igmp_type,
 288                                            BR_MCAST_DIR_TX);
 289
 290                 if ((unsigned long)lport >= (unsigned long)port)
 291                         p = rcu_dereference(p->next);
 292                 if ((unsigned long)rport >= (unsigned long)port)
 293                         rp = rcu_dereference(hlist_next_rcu(rp));
 294         }
 295
 296         if (!prev)
 297                 goto out;
 298
 299         if (local_rcv)
 300                 deliver_clone(prev, skb, local_orig);
 301         else
 302                 __br_forward(prev, skb, local_orig);
 303         return;
 304
 305 out:
 306         if (!local_rcv)
 307                 kfree_skb(skb);
 308 }
 309 #endif