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         /* drop mtu oversized packets except gso */
  45         if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
  46                 kfree_skb(skb);
  47         else {
  48                 /* ip_fragment doesn't copy the MAC header */
  49                 if (nf_bridge_maybe_copy_header(skb))
  50                         kfree_skb(skb);
  51                 else {
  52                         skb_push(skb, ETH_HLEN);
  53
  54 #ifdef CONFIG_NET_POLL_CONTROLLER
  55                         if (unlikely(skb->dev->priv_flags & IFF_IN_NETPOLL)) {
  56                                 netpoll_send_skb(skb->dev->npinfo->netpoll, skb);
  57                                 skb->dev->priv_flags &= ~IFF_IN_NETPOLL;
  58                         } else
  59 #endif
  60                                 dev_queue_xmit(skb);
  61                 }
  62         }
  63
  64         return 0;
  65 }
  66
  67 int br_forward_finish(struct sk_buff *skb)
  68 {
  69         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  70                        br_dev_queue_push_xmit);
  71
  72 }
  73
  74 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  75 {
  76 #ifdef CONFIG_NET_POLL_CONTROLLER
  77         struct net_bridge *br = to->br;
  78         if (unlikely(br->dev->priv_flags & IFF_IN_NETPOLL)) {
  79                 struct netpoll *np;
  80                 to->dev->npinfo = skb->dev->npinfo;
  81                 np = skb->dev->npinfo->netpoll;
  82                 np->real_dev = np->dev = to->dev;
  83                 to->dev->priv_flags |= IFF_IN_NETPOLL;
  84         }
  85 #endif
  86         skb->dev = to->dev;
  87         NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  88                 br_forward_finish);
  89 #ifdef CONFIG_NET_POLL_CONTROLLER
  90         if (skb->dev->npinfo)
  91                 skb->dev->npinfo->netpoll->dev = br->dev;
  92 #endif
  93 }
  94
  95 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  96 {
  97         struct net_device *indev;
  98
  99         if (skb_warn_if_lro(skb)) {
 100                 kfree_skb(skb);
 101                 return;
 102         }
 103
 104         indev = skb->dev;
 105         skb->dev = to->dev;
 106         skb_forward_csum(skb);
 107
 108         NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
 109                 br_forward_finish);
 110 }
 111
 112 /* called with rcu_read_lock */
 113 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 114 {
 115         if (should_deliver(to, skb)) {
 116                 __br_deliver(to, skb);
 117                 return;
 118         }
 119
 120         kfree_skb(skb);
 121 }
 122
 123 /* called with rcu_read_lock */
 124 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
 125 {
 126         if (should_deliver(to, skb)) {
 127                 if (skb0)
 128                         deliver_clone(to, skb, __br_forward);
 129                 else
 130                         __br_forward(to, skb);
 131                 return;
 132         }
 133
 134         if (!skb0)
 135                 kfree_skb(skb);
 136 }
 137
 138 static int deliver_clone(const struct net_bridge_port *prev,
 139                          struct sk_buff *skb,
 140                          void (*__packet_hook)(const struct net_bridge_port *p,
 141                                                struct sk_buff *skb))
 142 {
 143         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 144
 145         skb = skb_clone(skb, GFP_ATOMIC);
 146         if (!skb) {
 147                 dev->stats.tx_dropped++;
 148                 return -ENOMEM;
 149         }
 150
 151         __packet_hook(prev, skb);
 152         return 0;
 153 }
 154
 155 static struct net_bridge_port *maybe_deliver(
 156         struct net_bridge_port *prev, struct net_bridge_port *p,
 157         struct sk_buff *skb,
 158         void (*__packet_hook)(const struct net_bridge_port *p,
 159                               struct sk_buff *skb))
 160 {
 161         int err;
 162
 163         if (!should_deliver(p, skb))
 164                 return prev;
 165
 166         if (!prev)
 167                 goto out;
 168
 169         err = deliver_clone(prev, skb, __packet_hook);
 170         if (err)
 171                 return ERR_PTR(err);
 172
 173 out:
 174         return p;
 175 }
 176
 177 /* called under bridge lock */
 178 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 179                      struct sk_buff *skb0,
 180                      void (*__packet_hook)(const struct net_bridge_port *p,
 181                                            struct sk_buff *skb))
 182 {
 183         struct net_bridge_port *p;
 184         struct net_bridge_port *prev;
 185
 186         prev = NULL;
 187
 188         list_for_each_entry_rcu(p, &br->port_list, list) {
 189                 prev = maybe_deliver(prev, p, skb, __packet_hook);
 190                 if (IS_ERR(prev))
 191                         goto out;
 192         }
 193
 194         if (!prev)
 195                 goto out;
 196
 197         if (skb0)
 198                 deliver_clone(prev, skb, __packet_hook);
 199         else
 200                 __packet_hook(prev, skb);
 201         return;
 202
 203 out:
 204         if (!skb0)
 205                 kfree_skb(skb);
 206 }
 207
 208
 209 /* called with rcu_read_lock */
 210 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
 211 {
 212         br_flood(br, skb, NULL, __br_deliver);
 213 }
 214
 215 /* called under bridge lock */
 216 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
 217                       struct sk_buff *skb2)
 218 {
 219         br_flood(br, skb, skb2, __br_forward);
 220 }
 221
 222 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 223 /* called with rcu_read_lock */
 224 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 225                                struct sk_buff *skb, struct sk_buff *skb0,
 226                                void (*__packet_hook)(
 227                                         const struct net_bridge_port *p,
 228                                         struct sk_buff *skb))
 229 {
 230         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 231         struct net_bridge *br = netdev_priv(dev);
 232         struct net_bridge_port *prev = NULL;
 233         struct net_bridge_port_group *p;
 234         struct hlist_node *rp;
 235
 236         rp = rcu_dereference(br->router_list.first);
 237         p = mdst ? rcu_dereference(mdst->ports) : NULL;
 238         while (p || rp) {
 239                 struct net_bridge_port *port, *lport, *rport;
 240
 241                 lport = p ? p->port : NULL;
 242                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
 243                              NULL;
 244
 245                 port = (unsigned long)lport > (unsigned long)rport ?
 246                        lport : rport;
 247
 248                 prev = maybe_deliver(prev, port, skb, __packet_hook);
 249                 if (IS_ERR(prev))
 250                         goto out;
 251
 252                 if ((unsigned long)lport >= (unsigned long)port)
 253                         p = rcu_dereference(p->next);
 254                 if ((unsigned long)rport >= (unsigned long)port)
 255                         rp = rcu_dereference(rp->next);
 256         }
 257
 258         if (!prev)
 259                 goto out;
 260
 261         if (skb0)
 262                 deliver_clone(prev, skb, __packet_hook);
 263         else
 264                 __packet_hook(prev, skb);
 265         return;
 266
 267 out:
 268         if (!skb0)
 269                 kfree_skb(skb);
 270 }
 271
 272 /* called with rcu_read_lock */
 273 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
 274                           struct sk_buff *skb)
 275 {
 276         br_multicast_flood(mdst, skb, NULL, __br_deliver);
 277 }
 278
 279 /* called with rcu_read_lock */
 280 void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
 281                           struct sk_buff *skb, struct sk_buff *skb2)
 282 {
 283         br_multicast_flood(mdst, skb, skb2, __br_forward);
 284 }
 285 #endif