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