kernel/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                 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 sock *sk, struct sk_buff *skb)
  53 {
  54         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, sk, skb,
  55                        NULL, skb->dev,
  56                        br_dev_queue_push_xmit);
  57
  58 }
  59 EXPORT_SYMBOL_GPL(br_forward_finish);
  60
  61 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  62 {
  63         skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
  64         if (!skb)
  65                 return;
  66
  67         skb->dev = to->dev;
  68
  69         if (unlikely(netpoll_tx_running(to->br->dev))) {
  70                 if (!is_skb_forwardable(skb->dev, skb))
  71                         kfree_skb(skb);
  72                 else {
  73                         skb_push(skb, ETH_HLEN);
  74                         br_netpoll_send_skb(to, skb);
  75                 }
  76                 return;
  77         }
  78
  79         NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, NULL, skb,
  80                 NULL, skb->dev,
  81                 br_forward_finish);
  82 }
  83
  84 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  85 {
  86         struct net_device *indev;
  87
  88         if (skb_warn_if_lro(skb)) {
  89                 kfree_skb(skb);
  90                 return;
  91         }
  92
  93         skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
  94         if (!skb)
  95                 return;
  96
  97         indev = skb->dev;
  98         skb->dev = to->dev;
  99         skb_forward_csum(skb);
 100
 101         NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, NULL, skb,
 102                 indev, skb->dev,
 103                 br_forward_finish);
 104 }
 105
 106 /* called with rcu_read_lock */
 107 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 108 {
 109         if (to && should_deliver(to, skb)) {
 110                 __br_deliver(to, skb);
 111                 return;
 112         }
 113
 114         kfree_skb(skb);
 115 }
 116 EXPORT_SYMBOL_GPL(br_deliver);
 117
 118 /* called with rcu_read_lock */
 119 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
 120 {
 121         if (should_deliver(to, skb)) {
 122                 if (skb0)
 123                         deliver_clone(to, skb, __br_forward);
 124                 else
 125                         __br_forward(to, skb);
 126                 return;
 127         }
 128
 129         if (!skb0)
 130                 kfree_skb(skb);
 131 }
 132
 133 static int deliver_clone(const struct net_bridge_port *prev,
 134                          struct sk_buff *skb,
 135                          void (*__packet_hook)(const struct net_bridge_port *p,
 136                                                struct sk_buff *skb))
 137 {
 138         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 139
 140         skb = skb_clone(skb, GFP_ATOMIC);
 141         if (!skb) {
 142                 dev->stats.tx_dropped++;
 143                 return -ENOMEM;
 144         }
 145
 146         __packet_hook(prev, skb);
 147         return 0;
 148 }
 149
 150 static struct net_bridge_port *maybe_deliver(
 151         struct net_bridge_port *prev, struct net_bridge_port *p,
 152         struct sk_buff *skb,
 153         void (*__packet_hook)(const struct net_bridge_port *p,
 154                               struct sk_buff *skb))
 155 {
 156         int err;
 157
 158         if (!should_deliver(p, skb))
 159                 return prev;
 160
 161         if (!prev)
 162                 goto out;
 163
 164         err = deliver_clone(prev, skb, __packet_hook);
 165         if (err)
 166                 return ERR_PTR(err);
 167
 168 out:
 169         return p;
 170 }
 171
 172 /* called under bridge lock */
 173 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 174                      struct sk_buff *skb0,
 175                      void (*__packet_hook)(const struct net_bridge_port *p,
 176                                            struct sk_buff *skb),
 177                      bool unicast)
 178 {
 179         struct net_bridge_port *p;
 180         struct net_bridge_port *prev;
 181
 182         prev = NULL;
 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, __packet_hook);
 197                 if (IS_ERR(prev))
 198                         goto out;
 199         }
 200
 201         if (!prev)
 202                 goto out;
 203
 204         if (skb0)
 205                 deliver_clone(prev, skb, __packet_hook);
 206         else
 207                 __packet_hook(prev, skb);
 208         return;
 209
 210 out:
 211         if (!skb0)
 212                 kfree_skb(skb);
 213 }
 214
 215
 216 /* called with rcu_read_lock */
 217 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast)
 218 {
 219         br_flood(br, skb, NULL, __br_deliver, unicast);
 220 }
 221
 222 /* called under bridge lock */
 223 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
 224                       struct sk_buff *skb2, bool unicast)
 225 {
 226         br_flood(br, skb, skb2, __br_forward, unicast);
 227 }
 228
 229 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 230 /* called with rcu_read_lock */
 231 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 232                                struct sk_buff *skb, struct sk_buff *skb0,
 233                                void (*__packet_hook)(
 234                                         const struct net_bridge_port *p,
 235                                         struct sk_buff *skb))
 236 {
 237         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 238         struct net_bridge *br = netdev_priv(dev);
 239         struct net_bridge_port *prev = NULL;
 240         struct net_bridge_port_group *p;
 241         struct hlist_node *rp;
 242
 243         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
 244         p = mdst ? rcu_dereference(mdst->ports) : NULL;
 245         while (p || rp) {
 246                 struct net_bridge_port *port, *lport, *rport;
 247
 248                 lport = p ? p->port : NULL;
 249                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
 250                              NULL;
 251
 252                 port = (unsigned long)lport > (unsigned long)rport ?
 253                        lport : rport;
 254
 255                 prev = maybe_deliver(prev, port, skb, __packet_hook);
 256                 if (IS_ERR(prev))
 257                         goto out;
 258
 259                 if ((unsigned long)lport >= (unsigned long)port)
 260                         p = rcu_dereference(p->next);
 261                 if ((unsigned long)rport >= (unsigned long)port)
 262                         rp = rcu_dereference(hlist_next_rcu(rp));
 263         }
 264
 265         if (!prev)
 266                 goto out;
 267
 268         if (skb0)
 269                 deliver_clone(prev, skb, __packet_hook);
 270         else
 271                 __packet_hook(prev, skb);
 272         return;
 273
 274 out:
 275         if (!skb0)
 276                 kfree_skb(skb);
 277 }
 278
 279 /* called with rcu_read_lock */
 280 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
 281                           struct sk_buff *skb)
 282 {
 283         br_multicast_flood(mdst, skb, NULL, __br_deliver);
 284 }
 285
 286 /* called with rcu_read_lock */
 287 void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
 288                           struct sk_buff *skb, struct sk_buff *skb2)
 289 {
 290         br_multicast_flood(mdst, skb, skb2, __br_forward);
 291 }
 292 #endif