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 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                 dev_queue_xmit(skb);
  46         }
  47
  48         return 0;
  49 }
  50 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
  51
  52 int br_forward_finish(struct sk_buff *skb)
  53 {
  54         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  55                        br_dev_queue_push_xmit);
  56
  57 }
  58 EXPORT_SYMBOL_GPL(br_forward_finish);
  59
  60 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  61 {
  62         skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
  63         if (!skb)
  64                 return;
  65
  66         skb->dev = to->dev;
  67
  68         if (unlikely(netpoll_tx_running(to->br->dev))) {
  69                 if (!is_skb_forwardable(skb->dev, skb))
  70                         kfree_skb(skb);
  71                 else {
  72                         skb_push(skb, ETH_HLEN);
  73                         br_netpoll_send_skb(to, skb);
  74                 }
  75                 return;
  76         }
  77
  78         NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  79                 br_forward_finish);
  80 }
  81
  82 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  83 {
  84         struct net_device *indev;
  85
  86         if (skb_warn_if_lro(skb)) {
  87                 kfree_skb(skb);
  88                 return;
  89         }
  90
  91         skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
  92         if (!skb)
  93                 return;
  94
  95         indev = skb->dev;
  96         skb->dev = to->dev;
  97         skb_forward_csum(skb);
  98
  99         NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
 100                 br_forward_finish);
 101 }
 102
 103 /* called with rcu_read_lock */
 104 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 105 {
 106         if (to && should_deliver(to, skb)) {
 107                 __br_deliver(to, skb);
 108                 return;
 109         }
 110
 111         kfree_skb(skb);
 112 }
 113 EXPORT_SYMBOL_GPL(br_deliver);
 114
 115 /* called with rcu_read_lock */
 116 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
 117 {
 118         if (should_deliver(to, skb)) {
 119                 if (skb0)
 120                         deliver_clone(to, skb, __br_forward);
 121                 else
 122                         __br_forward(to, skb);
 123                 return;
 124         }
 125
 126         if (!skb0)
 127                 kfree_skb(skb);
 128 }
 129
 130 static int deliver_clone(const struct net_bridge_port *prev,
 131                          struct sk_buff *skb,
 132                          void (*__packet_hook)(const struct net_bridge_port *p,
 133                                                struct sk_buff *skb))
 134 {
 135         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 136
 137         skb = skb_clone(skb, GFP_ATOMIC);
 138         if (!skb) {
 139                 dev->stats.tx_dropped++;
 140                 return -ENOMEM;
 141         }
 142
 143         __packet_hook(prev, skb);
 144         return 0;
 145 }
 146
 147 static struct net_bridge_port *maybe_deliver(
 148         struct net_bridge_port *prev, struct net_bridge_port *p,
 149         struct sk_buff *skb,
 150         void (*__packet_hook)(const struct net_bridge_port *p,
 151                               struct sk_buff *skb))
 152 {
 153         int err;
 154
 155         if (!should_deliver(p, skb))
 156                 return prev;
 157
 158         if (!prev)
 159                 goto out;
 160
 161         err = deliver_clone(prev, skb, __packet_hook);
 162         if (err)
 163                 return ERR_PTR(err);
 164
 165 out:
 166         return p;
 167 }
 168
 169 /* called under bridge lock */
 170 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 171                      struct sk_buff *skb0,
 172                      void (*__packet_hook)(const struct net_bridge_port *p,
 173                                            struct sk_buff *skb),
 174                      bool unicast)
 175 {
 176         struct net_bridge_port *p;
 177         struct net_bridge_port *prev;
 178
 179         prev = NULL;
 180
 181         list_for_each_entry_rcu(p, &br->port_list, list) {
 182                 /* Do not flood unicast traffic to ports that turn it off */
 183                 if (unicast && !(p->flags & BR_FLOOD))
 184                         continue;
 185
 186                 /* Do not flood to ports that enable proxy ARP */
 187                 if (p->flags & BR_PROXYARP)
 188                         continue;
 189                 if ((p->flags & BR_PROXYARP_WIFI) &&
 190                     BR_INPUT_SKB_CB(skb)->proxyarp_replied)
 191                         continue;
 192
 193                 prev = maybe_deliver(prev, p, skb, __packet_hook);
 194                 if (IS_ERR(prev))
 195                         goto out;
 196         }
 197
 198         if (!prev)
 199                 goto out;
 200
 201         if (skb0)
 202                 deliver_clone(prev, skb, __packet_hook);
 203         else
 204                 __packet_hook(prev, skb);
 205         return;
 206
 207 out:
 208         if (!skb0)
 209                 kfree_skb(skb);
 210 }
 211
 212
 213 /* called with rcu_read_lock */
 214 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast)
 215 {
 216         br_flood(br, skb, NULL, __br_deliver, unicast);
 217 }
 218
 219 /* called under bridge lock */
 220 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
 221                       struct sk_buff *skb2, bool unicast)
 222 {
 223         br_flood(br, skb, skb2, __br_forward, unicast);
 224 }
 225
 226 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 227 /* called with rcu_read_lock */
 228 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 229                                struct sk_buff *skb, struct sk_buff *skb0,
 230                                void (*__packet_hook)(
 231                                         const struct net_bridge_port *p,
 232                                         struct sk_buff *skb))
 233 {
 234         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 235         struct net_bridge *br = netdev_priv(dev);
 236         struct net_bridge_port *prev = NULL;
 237         struct net_bridge_port_group *p;
 238         struct hlist_node *rp;
 239
 240         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
 241         p = mdst ? rcu_dereference(mdst->ports) : NULL;
 242         while (p || rp) {
 243                 struct net_bridge_port *port, *lport, *rport;
 244
 245                 lport = p ? p->port : NULL;
 246                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
 247                              NULL;
 248
 249                 port = (unsigned long)lport > (unsigned long)rport ?
 250                        lport : rport;
 251
 252                 prev = maybe_deliver(prev, port, skb, __packet_hook);
 253                 if (IS_ERR(prev))
 254                         goto out;
 255
 256                 if ((unsigned long)lport >= (unsigned long)port)
 257                         p = rcu_dereference(p->next);
 258                 if ((unsigned long)rport >= (unsigned long)port)
 259                         rp = rcu_dereference(hlist_next_rcu(rp));
 260         }
 261
 262         if (!prev)
 263                 goto out;
 264
 265         if (skb0)
 266                 deliver_clone(prev, skb, __packet_hook);
 267         else
 268                 __packet_hook(prev, skb);
 269         return;
 270
 271 out:
 272         if (!skb0)
 273                 kfree_skb(skb);
 274 }
 275
 276 /* called with rcu_read_lock */
 277 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
 278                           struct sk_buff *skb)
 279 {
 280         br_multicast_flood(mdst, skb, NULL, __br_deliver);
 281 }
 282
 283 /* called with rcu_read_lock */
 284 void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
 285                           struct sk_buff *skb, struct sk_buff *skb2)
 286 {
 287         br_multicast_flood(mdst, skb, skb2, __br_forward);
 288 }
 289 #endif