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/skbuff.h>
  19 #include <linux/if_vlan.h>
  20 #include <linux/netfilter_bridge.h>
  21 #include "br_private.h"
  22
  23 static int deliver_clone(const struct net_bridge_port *prev,
  24                          struct sk_buff *skb,
  25                          void (*__packet_hook)(const struct net_bridge_port *p,
  26                                                struct sk_buff *skb));
  27
  28 /* Don't forward packets to originating port or forwarding diasabled */
  29 static inline int should_deliver(const struct net_bridge_port *p,
  30                                  const struct sk_buff *skb)
  31 {
  32         return (((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
  33                 p->state == BR_STATE_FORWARDING);
  34 }
  35
  36 static inline unsigned packet_length(const struct sk_buff *skb)
  37 {
  38         return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
  39 }
  40
  41 int br_dev_queue_push_xmit(struct sk_buff *skb)
  42 {
  43         /* drop mtu oversized packets except gso */
  44         if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
  45                 kfree_skb(skb);
  46         else {
  47                 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
  48                 if (nf_bridge_maybe_copy_header(skb))
  49                         kfree_skb(skb);
  50                 else {
  51                         skb_push(skb, ETH_HLEN);
  52
  53                         dev_queue_xmit(skb);
  54                 }
  55         }
  56
  57         return 0;
  58 }
  59
  60 int br_forward_finish(struct sk_buff *skb)
  61 {
  62         return NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  63                        br_dev_queue_push_xmit);
  64
  65 }
  66
  67 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  68 {
  69         skb->dev = to->dev;
  70         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  71                         br_forward_finish);
  72 }
  73
  74 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  75 {
  76         struct net_device *indev;
  77
  78         if (skb_warn_if_lro(skb)) {
  79                 kfree_skb(skb);
  80                 return;
  81         }
  82
  83         indev = skb->dev;
  84         skb->dev = to->dev;
  85         skb_forward_csum(skb);
  86
  87         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
  88                         br_forward_finish);
  89 }
  90
  91 /* called with rcu_read_lock */
  92 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  93 {
  94         if (should_deliver(to, skb)) {
  95                 __br_deliver(to, skb);
  96                 return;
  97         }
  98
  99         kfree_skb(skb);
 100 }
 101
 102 /* called with rcu_read_lock */
 103 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
 104 {
 105         if (should_deliver(to, skb)) {
 106                 if (skb0)
 107                         deliver_clone(to, skb, __br_forward);
 108                 else
 109                         __br_forward(to, skb);
 110                 return;
 111         }
 112
 113         if (!skb0)
 114                 kfree_skb(skb);
 115 }
 116
 117 static int deliver_clone(const struct net_bridge_port *prev,
 118                          struct sk_buff *skb,
 119                          void (*__packet_hook)(const struct net_bridge_port *p,
 120                                                struct sk_buff *skb))
 121 {
 122         skb = skb_clone(skb, GFP_ATOMIC);
 123         if (!skb) {
 124                 struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 125
 126                 dev->stats.tx_dropped++;
 127                 return -ENOMEM;
 128         }
 129
 130         __packet_hook(prev, skb);
 131         return 0;
 132 }
 133
 134 static struct net_bridge_port *maybe_deliver(
 135         struct net_bridge_port *prev, struct net_bridge_port *p,
 136         struct sk_buff *skb,
 137         void (*__packet_hook)(const struct net_bridge_port *p,
 138                               struct sk_buff *skb))
 139 {
 140         int err;
 141
 142         if (!should_deliver(p, skb))
 143                 return prev;
 144
 145         if (!prev)
 146                 goto out;
 147
 148         err = deliver_clone(prev, skb, __packet_hook);
 149         if (err)
 150                 return ERR_PTR(err);
 151
 152 out:
 153         return p;
 154 }
 155
 156 /* called under bridge lock */
 157 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 158                      struct sk_buff *skb0,
 159                      void (*__packet_hook)(const struct net_bridge_port *p,
 160                                            struct sk_buff *skb))
 161 {
 162         struct net_bridge_port *p;
 163         struct net_bridge_port *prev;
 164
 165         prev = NULL;
 166
 167         list_for_each_entry_rcu(p, &br->port_list, list) {
 168                 prev = maybe_deliver(prev, p, skb, __packet_hook);
 169                 if (IS_ERR(prev))
 170                         goto out;
 171         }
 172
 173         if (!prev)
 174                 goto out;
 175
 176         if (skb0)
 177                 deliver_clone(prev, skb, __packet_hook);
 178         else
 179                 __packet_hook(prev, skb);
 180         return;
 181
 182 out:
 183         if (!skb0)
 184                 kfree_skb(skb);
 185 }
 186
 187
 188 /* called with rcu_read_lock */
 189 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
 190 {
 191         br_flood(br, skb, NULL, __br_deliver);
 192 }
 193
 194 /* called under bridge lock */
 195 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
 196                       struct sk_buff *skb2)
 197 {
 198         br_flood(br, skb, skb2, __br_forward);
 199 }
 200
 201 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 202 /* called with rcu_read_lock */
 203 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 204                                struct sk_buff *skb, struct sk_buff *skb0,
 205                                void (*__packet_hook)(
 206                                         const struct net_bridge_port *p,
 207                                         struct sk_buff *skb))
 208 {
 209         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 210         struct net_bridge *br = netdev_priv(dev);
 211         struct net_bridge_port *port;
 212         struct net_bridge_port *lport, *rport;
 213         struct net_bridge_port *prev;
 214         struct net_bridge_port_group *p;
 215         struct hlist_node *rp;
 216
 217         prev = NULL;
 218
 219         rp = br->router_list.first;
 220         p = mdst ? mdst->ports : NULL;
 221         while (p || rp) {
 222                 lport = p ? p->port : NULL;
 223                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
 224                              NULL;
 225
 226                 port = (unsigned long)lport > (unsigned long)rport ?
 227                        lport : rport;
 228
 229                 prev = maybe_deliver(prev, port, skb, __packet_hook);
 230                 if (IS_ERR(prev))
 231                         goto out;
 232
 233                 if ((unsigned long)lport >= (unsigned long)port)
 234                         p = p->next;
 235                 if ((unsigned long)rport >= (unsigned long)port)
 236                         rp = rp->next;
 237         }
 238
 239         if (!prev)
 240                 goto out;
 241
 242         if (skb0)
 243                 deliver_clone(prev, skb, __packet_hook);
 244         else
 245                 __packet_hook(prev, skb);
 246         return;
 247
 248 out:
 249         if (!skb0)
 250                 kfree_skb(skb);
 251 }
 252
 253 /* called with rcu_read_lock */
 254 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
 255                           struct sk_buff *skb)
 256 {
 257         br_multicast_flood(mdst, skb, NULL, __br_deliver);
 258 }
 259
 260 /* called with rcu_read_lock */
 261 void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
 262                           struct sk_buff *skb, struct sk_buff *skb2)
 263 {
 264         br_multicast_flood(mdst, skb, skb2, __br_forward);
 265 }
 266 #endif