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 }
  34
  35 int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
  36 {
  37         if (!is_skb_forwardable(skb->dev, skb))
  38                 goto drop;
  39
  40         skb_push(skb, ETH_HLEN);
  41         br_drop_fake_rtable(skb);
  42
  43         if (skb->ip_summed == CHECKSUM_PARTIAL &&
  44             (skb->protocol == htons(ETH_P_8021Q) ||
  45              skb->protocol == htons(ETH_P_8021AD))) {
  46                 int depth;
  47
  48                 if (!__vlan_get_protocol(skb, skb->protocol, &depth))
  49                         goto drop;
  50
  51                 skb_set_network_header(skb, depth);
  52         }
  53
  54         dev_queue_xmit(skb);
  55
  56         return 0;
  57
  58 drop:
  59         kfree_skb(skb);
  60         return 0;
  61 }
  62 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
  63
  64 int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
  65 {
  66         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING,
  67                        net, sk, skb, NULL, skb->dev,
  68                        br_dev_queue_push_xmit);
  69
  70 }
  71 EXPORT_SYMBOL_GPL(br_forward_finish);
  72
  73 static void __br_forward(const struct net_bridge_port *to,
  74                          struct sk_buff *skb, bool local_orig)
  75 {
  76         struct net_bridge_vlan_group *vg;
  77         struct net_device *indev;
  78         struct net *net;
  79         int br_hook;
  80
  81         vg = nbp_vlan_group_rcu(to);
  82         skb = br_handle_vlan(to->br, vg, skb);
  83         if (!skb)
  84                 return;
  85
  86         indev = skb->dev;
  87         skb->dev = to->dev;
  88         if (!local_orig) {
  89                 if (skb_warn_if_lro(skb)) {
  90                         kfree_skb(skb);
  91                         return;
  92                 }
  93                 br_hook = NF_BR_FORWARD;
  94                 skb_forward_csum(skb);
  95                 net = dev_net(indev);
  96         } else {
  97                 if (unlikely(netpoll_tx_running(to->br->dev))) {
  98                         if (!is_skb_forwardable(skb->dev, skb)) {
  99                                 kfree_skb(skb);
 100                         } else {
 101                                 skb_push(skb, ETH_HLEN);
 102                                 br_netpoll_send_skb(to, skb);
 103                         }
 104                         return;
 105                 }
 106                 br_hook = NF_BR_LOCAL_OUT;
 107                 net = dev_net(skb->dev);
 108                 indev = NULL;
 109         }
 110
 111         NF_HOOK(NFPROTO_BRIDGE, br_hook,
 112                 net, NULL, skb, indev, skb->dev,
 113                 br_forward_finish);
 114 }
 115
 116 static int deliver_clone(const struct net_bridge_port *prev,
 117                          struct sk_buff *skb, bool local_orig)
 118 {
 119         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 120
 121         skb = skb_clone(skb, GFP_ATOMIC);
 122         if (!skb) {
 123                 dev->stats.tx_dropped++;
 124                 return -ENOMEM;
 125         }
 126
 127         __br_forward(prev, skb, local_orig);
 128         return 0;
 129 }
 130
 131 /**
 132  * br_forward - forward a packet to a specific port
 133  * @to: destination port
 134  * @skb: packet being forwarded
 135  * @local_rcv: packet will be received locally after forwarding
 136  * @local_orig: packet is locally originated
 137  *
 138  * Should be called with rcu_read_lock.
 139  */
 140 void br_forward(const struct net_bridge_port *to,
 141                 struct sk_buff *skb, bool local_rcv, bool local_orig)
 142 {
 143         if (to && should_deliver(to, skb)) {
 144                 if (local_rcv)
 145                         deliver_clone(to, skb, local_orig);
 146                 else
 147                         __br_forward(to, skb, local_orig);
 148                 return;
 149         }
 150
 151         if (!local_rcv)
 152                 kfree_skb(skb);
 153 }
 154 EXPORT_SYMBOL_GPL(br_forward);
 155
 156 static struct net_bridge_port *maybe_deliver(
 157         struct net_bridge_port *prev, struct net_bridge_port *p,
 158         struct sk_buff *skb, bool local_orig)
 159 {
 160         int err;
 161
 162         if (!should_deliver(p, skb))
 163                 return prev;
 164
 165         if (!prev)
 166                 goto out;
 167
 168         err = deliver_clone(prev, skb, local_orig);
 169         if (err)
 170                 return ERR_PTR(err);
 171
 172 out:
 173         return p;
 174 }
 175
 176 /* called under rcu_read_lock */
 177 void br_flood(struct net_bridge *br, struct sk_buff *skb,
 178               bool unicast, bool local_rcv, bool local_orig)
 179 {
 180         u8 igmp_type = br_multicast_igmp_type(skb);
 181         struct net_bridge_port *prev = NULL;
 182         struct net_bridge_port *p;
 183
 184         list_for_each_entry_rcu(p, &br->port_list, list) {
 185                 /* Do not flood unicast traffic to ports that turn it off */
 186                 if (unicast && !(p->flags & BR_FLOOD))
 187                         continue;
 188
 189                 /* Do not flood to ports that enable proxy ARP */
 190                 if (p->flags & BR_PROXYARP)
 191                         continue;
 192                 if ((p->flags & BR_PROXYARP_WIFI) &&
 193                     BR_INPUT_SKB_CB(skb)->proxyarp_replied)
 194                         continue;
 195
 196                 prev = maybe_deliver(prev, p, skb, local_orig);
 197                 if (IS_ERR(prev))
 198                         goto out;
 199                 if (prev == p)
 200                         br_multicast_count(p->br, p, skb, igmp_type,
 201                                            BR_MCAST_DIR_TX);
 202         }
 203
 204         if (!prev)
 205                 goto out;
 206
 207         if (local_rcv)
 208                 deliver_clone(prev, skb, local_orig);
 209         else
 210                 __br_forward(prev, skb, local_orig);
 211         return;
 212
 213 out:
 214         if (!local_rcv)
 215                 kfree_skb(skb);
 216 }
 217
 218 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 219 /* called with rcu_read_lock */
 220 void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 221                         struct sk_buff *skb,
 222                         bool local_rcv, bool local_orig)
 223 {
 224         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 225         u8 igmp_type = br_multicast_igmp_type(skb);
 226         struct net_bridge *br = netdev_priv(dev);
 227         struct net_bridge_port *prev = NULL;
 228         struct net_bridge_port_group *p;
 229         struct hlist_node *rp;
 230
 231         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
 232         p = mdst ? rcu_dereference(mdst->ports) : NULL;
 233         while (p || rp) {
 234                 struct net_bridge_port *port, *lport, *rport;
 235
 236                 lport = p ? p->port : NULL;
 237                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
 238                              NULL;
 239
 240                 port = (unsigned long)lport > (unsigned long)rport ?
 241                        lport : rport;
 242
 243                 prev = maybe_deliver(prev, port, skb, local_orig);
 244                 if (IS_ERR(prev))
 245                         goto out;
 246                 if (prev == port)
 247                         br_multicast_count(port->br, port, skb, igmp_type,
 248                                            BR_MCAST_DIR_TX);
 249
 250                 if ((unsigned long)lport >= (unsigned long)port)
 251                         p = rcu_dereference(p->next);
 252                 if ((unsigned long)rport >= (unsigned long)port)
 253                         rp = rcu_dereference(hlist_next_rcu(rp));
 254         }
 255
 256         if (!prev)
 257                 goto out;
 258
 259         if (local_rcv)
 260                 deliver_clone(prev, skb, local_orig);
 261         else
 262                 __br_forward(prev, skb, local_orig);
 263         return;
 264
 265 out:
 266         if (!local_rcv)
 267                 kfree_skb(skb);
 268 }
 269 #endif