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 static int deliver_clone(const struct net_bridge_port *prev,
  25                          struct sk_buff *skb,
  26                          void (*__packet_hook)(const struct net_bridge_port *p,
  27                                                struct sk_buff *skb));
  28
  29 /* Don't forward packets to originating port or forwarding disabled */
  30 static inline int should_deliver(const struct net_bridge_port *p,
  31                                  const struct sk_buff *skb)
  32 {
  33         return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
  34                 br_allowed_egress(p->br, nbp_get_vlan_info(p), skb) &&
  35                 p->state == BR_STATE_FORWARDING;
  36 }
  37
  38 int br_dev_queue_push_xmit(struct sock *sk, struct sk_buff *skb)
  39 {
  40         if (!is_skb_forwardable(skb->dev, skb)) {
  41                 kfree_skb(skb);
  42         } else {
  43                 skb_push(skb, ETH_HLEN);
  44                 br_drop_fake_rtable(skb);
  45                 skb_sender_cpu_clear(skb);
  46                 dev_queue_xmit(skb);
  47         }
  48
  49         return 0;
  50 }
  51 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
  52
  53 int br_forward_finish(struct sock *sk, struct sk_buff *skb)
  54 {
  55         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, sk, skb,
  56                        NULL, skb->dev,
  57                        br_dev_queue_push_xmit);
  58
  59 }
  60 EXPORT_SYMBOL_GPL(br_forward_finish);
  61
  62 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  63 {
  64         skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
  65         if (!skb)
  66                 return;
  67
  68         skb->dev = to->dev;
  69
  70         if (unlikely(netpoll_tx_running(to->br->dev))) {
  71                 if (!is_skb_forwardable(skb->dev, skb))
  72                         kfree_skb(skb);
  73                 else {
  74                         skb_push(skb, ETH_HLEN);
  75                         br_netpoll_send_skb(to, skb);
  76                 }
  77                 return;
  78         }
  79
  80         NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, NULL, skb,
  81                 NULL, skb->dev,
  82                 br_forward_finish);
  83 }
  84
  85 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  86 {
  87         struct net_device *indev;
  88
  89         if (skb_warn_if_lro(skb)) {
  90                 kfree_skb(skb);
  91                 return;
  92         }
  93
  94         skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
  95         if (!skb)
  96                 return;
  97
  98         indev = skb->dev;
  99         skb->dev = to->dev;
 100         skb_forward_csum(skb);
 101
 102         NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, NULL, skb,
 103                 indev, skb->dev,
 104                 br_forward_finish);
 105 }
 106
 107 /* called with rcu_read_lock */
 108 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 109 {
 110         if (to && should_deliver(to, skb)) {
 111                 __br_deliver(to, skb);
 112                 return;
 113         }
 114
 115         kfree_skb(skb);
 116 }
 117 EXPORT_SYMBOL_GPL(br_deliver);
 118
 119 /* called with rcu_read_lock */
 120 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
 121 {
 122         if (should_deliver(to, skb)) {
 123                 if (skb0)
 124                         deliver_clone(to, skb, __br_forward);
 125                 else
 126                         __br_forward(to, skb);
 127                 return;
 128         }
 129
 130         if (!skb0)
 131                 kfree_skb(skb);
 132 }
 133
 134 static int deliver_clone(const struct net_bridge_port *prev,
 135                          struct sk_buff *skb,
 136                          void (*__packet_hook)(const struct net_bridge_port *p,
 137                                                struct sk_buff *skb))
 138 {
 139         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 140
 141         skb = skb_clone(skb, GFP_ATOMIC);
 142         if (!skb) {
 143                 dev->stats.tx_dropped++;
 144                 return -ENOMEM;
 145         }
 146
 147         __packet_hook(prev, skb);
 148         return 0;
 149 }
 150
 151 static struct net_bridge_port *maybe_deliver(
 152         struct net_bridge_port *prev, struct net_bridge_port *p,
 153         struct sk_buff *skb,
 154         void (*__packet_hook)(const struct net_bridge_port *p,
 155                               struct sk_buff *skb))
 156 {
 157         int err;
 158
 159         if (!should_deliver(p, skb))
 160                 return prev;
 161
 162         if (!prev)
 163                 goto out;
 164
 165         err = deliver_clone(prev, skb, __packet_hook);
 166         if (err)
 167                 return ERR_PTR(err);
 168
 169 out:
 170         return p;
 171 }
 172
 173 /* called under bridge lock */
 174 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 175                      struct sk_buff *skb0,
 176                      void (*__packet_hook)(const struct net_bridge_port *p,
 177                                            struct sk_buff *skb),
 178                      bool unicast)
 179 {
 180         struct net_bridge_port *p;
 181         struct net_bridge_port *prev;
 182
 183         prev = NULL;
 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 (unicast && !(p->flags & BR_FLOOD))
 188                         continue;
 189
 190                 /* Do not flood to ports that enable proxy ARP */
 191                 if (p->flags & BR_PROXYARP)
 192                         continue;
 193                 if ((p->flags & BR_PROXYARP_WIFI) &&
 194                     BR_INPUT_SKB_CB(skb)->proxyarp_replied)
 195                         continue;
 196
 197                 prev = maybe_deliver(prev, p, skb, __packet_hook);
 198                 if (IS_ERR(prev))
 199                         goto out;
 200         }
 201
 202         if (!prev)
 203                 goto out;
 204
 205         if (skb0)
 206                 deliver_clone(prev, skb, __packet_hook);
 207         else
 208                 __packet_hook(prev, skb);
 209         return;
 210
 211 out:
 212         if (!skb0)
 213                 kfree_skb(skb);
 214 }
 215
 216
 217 /* called with rcu_read_lock */
 218 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast)
 219 {
 220         br_flood(br, skb, NULL, __br_deliver, unicast);
 221 }
 222
 223 /* called under bridge lock */
 224 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
 225                       struct sk_buff *skb2, bool unicast)
 226 {
 227         br_flood(br, skb, skb2, __br_forward, unicast);
 228 }
 229
 230 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 231 /* called with rcu_read_lock */
 232 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 233                                struct sk_buff *skb, struct sk_buff *skb0,
 234                                void (*__packet_hook)(
 235                                         const struct net_bridge_port *p,
 236                                         struct sk_buff *skb))
 237 {
 238         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 239         struct net_bridge *br = netdev_priv(dev);
 240         struct net_bridge_port *prev = NULL;
 241         struct net_bridge_port_group *p;
 242         struct hlist_node *rp;
 243
 244         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
 245         p = mdst ? rcu_dereference(mdst->ports) : NULL;
 246         while (p || rp) {
 247                 struct net_bridge_port *port, *lport, *rport;
 248
 249                 lport = p ? p->port : NULL;
 250                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
 251                              NULL;
 252
 253                 port = (unsigned long)lport > (unsigned long)rport ?
 254                        lport : rport;
 255
 256                 prev = maybe_deliver(prev, port, skb, __packet_hook);
 257                 if (IS_ERR(prev))
 258                         goto out;
 259
 260                 if ((unsigned long)lport >= (unsigned long)port)
 261                         p = rcu_dereference(p->next);
 262                 if ((unsigned long)rport >= (unsigned long)port)
 263                         rp = rcu_dereference(hlist_next_rcu(rp));
 264         }
 265
 266         if (!prev)
 267                 goto out;
 268
 269         if (skb0)
 270                 deliver_clone(prev, skb, __packet_hook);
 271         else
 272                 __packet_hook(prev, skb);
 273         return;
 274
 275 out:
 276         if (!skb0)
 277                 kfree_skb(skb);
 278 }
 279
 280 /* called with rcu_read_lock */
 281 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
 282                           struct sk_buff *skb)
 283 {
 284         br_multicast_flood(mdst, skb, NULL, __br_deliver);
 285 }
 286
 287 /* called with rcu_read_lock */
 288 void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
 289                           struct sk_buff *skb, struct sk_buff *skb2)
 290 {
 291         br_multicast_flood(mdst, skb, skb2, __br_forward);
 292 }
 293 #endif