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