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 diasabled */
  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                 p->state == BR_STATE_FORWARDING);
  35 }
  36
  37 static inline unsigned packet_length(const struct sk_buff *skb)
  38 {
  39         return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
  40 }
  41
  42 int br_dev_queue_push_xmit(struct sk_buff *skb)
  43 {
  44         /* ip_fragment doesn't copy the MAC header */
  45         if (nf_bridge_maybe_copy_header(skb) ||
  46             (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))) {
  47                 kfree_skb(skb);
  48         } else {
  49                 skb_push(skb, ETH_HLEN);
  50                 br_drop_fake_rtable(skb);
  51                 dev_queue_xmit(skb);
  52         }
  53
  54         return 0;
  55 }
  56
  57 int br_forward_finish(struct sk_buff *skb)
  58 {
  59         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  60                        br_dev_queue_push_xmit);
  61
  62 }
  63
  64 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  65 {
  66         skb->dev = to->dev;
  67
  68         if (unlikely(netpoll_tx_running(to->dev))) {
  69                 if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(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         indev = skb->dev;
  92         skb->dev = to->dev;
  93         skb_forward_csum(skb);
  94
  95         NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
  96                 br_forward_finish);
  97 }
  98
  99 /* called with rcu_read_lock */
 100 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 101 {
 102         if (should_deliver(to, skb)) {
 103                 __br_deliver(to, skb);
 104                 return;
 105         }
 106
 107         kfree_skb(skb);
 108 }
 109
 110 /* called with rcu_read_lock */
 111 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
 112 {
 113         if (should_deliver(to, skb)) {
 114                 if (skb0)
 115                         deliver_clone(to, skb, __br_forward);
 116                 else
 117                         __br_forward(to, skb);
 118                 return;
 119         }
 120
 121         if (!skb0)
 122                 kfree_skb(skb);
 123 }
 124
 125 static int deliver_clone(const struct net_bridge_port *prev,
 126                          struct sk_buff *skb,
 127                          void (*__packet_hook)(const struct net_bridge_port *p,
 128                                                struct sk_buff *skb))
 129 {
 130         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 131
 132         skb = skb_clone(skb, GFP_ATOMIC);
 133         if (!skb) {
 134                 dev->stats.tx_dropped++;
 135                 return -ENOMEM;
 136         }
 137
 138         __packet_hook(prev, skb);
 139         return 0;
 140 }
 141
 142 static struct net_bridge_port *maybe_deliver(
 143         struct net_bridge_port *prev, struct net_bridge_port *p,
 144         struct sk_buff *skb,
 145         void (*__packet_hook)(const struct net_bridge_port *p,
 146                               struct sk_buff *skb))
 147 {
 148         int err;
 149
 150         if (!should_deliver(p, skb))
 151                 return prev;
 152
 153         if (!prev)
 154                 goto out;
 155
 156         err = deliver_clone(prev, skb, __packet_hook);
 157         if (err)
 158                 return ERR_PTR(err);
 159
 160 out:
 161         return p;
 162 }
 163
 164 /* called under bridge lock */
 165 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 166                      struct sk_buff *skb0,
 167                      void (*__packet_hook)(const struct net_bridge_port *p,
 168                                            struct sk_buff *skb))
 169 {
 170         struct net_bridge_port *p;
 171         struct net_bridge_port *prev;
 172
 173         prev = NULL;
 174
 175         list_for_each_entry_rcu(p, &br->port_list, list) {
 176                 prev = maybe_deliver(prev, p, skb, __packet_hook);
 177                 if (IS_ERR(prev))
 178                         goto out;
 179         }
 180
 181         if (!prev)
 182                 goto out;
 183
 184         if (skb0)
 185                 deliver_clone(prev, skb, __packet_hook);
 186         else
 187                 __packet_hook(prev, skb);
 188         return;
 189
 190 out:
 191         if (!skb0)
 192                 kfree_skb(skb);
 193 }
 194
 195
 196 /* called with rcu_read_lock */
 197 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
 198 {
 199         br_flood(br, skb, NULL, __br_deliver);
 200 }
 201
 202 /* called under bridge lock */
 203 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
 204                       struct sk_buff *skb2)
 205 {
 206         br_flood(br, skb, skb2, __br_forward);
 207 }
 208
 209 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 210 /* called with rcu_read_lock */
 211 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 212                                struct sk_buff *skb, struct sk_buff *skb0,
 213                                void (*__packet_hook)(
 214                                         const struct net_bridge_port *p,
 215                                         struct sk_buff *skb))
 216 {
 217         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 218         struct net_bridge *br = netdev_priv(dev);
 219         struct net_bridge_port *prev = NULL;
 220         struct net_bridge_port_group *p;
 221         struct hlist_node *rp;
 222
 223         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
 224         p = mdst ? rcu_dereference(mdst->ports) : NULL;
 225         while (p || rp) {
 226                 struct net_bridge_port *port, *lport, *rport;
 227
 228                 lport = p ? p->port : NULL;
 229                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
 230                              NULL;
 231
 232                 port = (unsigned long)lport > (unsigned long)rport ?
 233                        lport : rport;
 234
 235                 prev = maybe_deliver(prev, port, skb, __packet_hook);
 236                 if (IS_ERR(prev))
 237                         goto out;
 238
 239                 if ((unsigned long)lport >= (unsigned long)port)
 240                         p = rcu_dereference(p->next);
 241                 if ((unsigned long)rport >= (unsigned long)port)
 242                         rp = rcu_dereference(hlist_next_rcu(rp));
 243         }
 244
 245         if (!prev)
 246                 goto out;
 247
 248         if (skb0)
 249                 deliver_clone(prev, skb, __packet_hook);
 250         else
 251                 __packet_hook(prev, skb);
 252         return;
 253
 254 out:
 255         if (!skb0)
 256                 kfree_skb(skb);
 257 }
 258
 259 /* called with rcu_read_lock */
 260 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
 261                           struct sk_buff *skb)
 262 {
 263         br_multicast_flood(mdst, skb, NULL, __br_deliver);
 264 }
 265
 266 /* called with rcu_read_lock */
 267 void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
 268                           struct sk_buff *skb, struct sk_buff *skb2)
 269 {
 270         br_multicast_flood(mdst, skb, skb2, __br_forward);
 271 }
 272 #endif