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 static inline unsigned int packet_length(const struct sk_buff *skb)
  39 {
  40         return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
  41 }
  42
  43 int br_dev_queue_push_xmit(struct sk_buff *skb)
  44 {
  45         /* ip_fragment doesn't copy the MAC header */
  46         if (nf_bridge_maybe_copy_header(skb) ||
  47             (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))) {
  48                 kfree_skb(skb);
  49         } else {
  50                 skb_push(skb, ETH_HLEN);
  51                 br_drop_fake_rtable(skb);
  52                 dev_queue_xmit(skb);
  53         }
  54
  55         return 0;
  56 }
  57
  58 int br_forward_finish(struct sk_buff *skb)
  59 {
  60         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  61                        br_dev_queue_push_xmit);
  62
  63 }
  64
  65 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  66 {
  67         skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
  68         if (!skb)
  69                 return;
  70
  71         skb->dev = to->dev;
  72
  73         if (unlikely(netpoll_tx_running(to->br->dev))) {
  74                 if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
  75                         kfree_skb(skb);
  76                 else {
  77                         skb_push(skb, ETH_HLEN);
  78                         br_netpoll_send_skb(to, skb);
  79                 }
  80                 return;
  81         }
  82
  83         NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  84                 br_forward_finish);
  85 }
  86
  87 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  88 {
  89         struct net_device *indev;
  90
  91         if (skb_warn_if_lro(skb)) {
  92                 kfree_skb(skb);
  93                 return;
  94         }
  95
  96         skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
  97         if (!skb)
  98                 return;
  99
 100         indev = skb->dev;
 101         skb->dev = to->dev;
 102         skb_forward_csum(skb);
 103
 104         NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
 105                 br_forward_finish);
 106 }
 107
 108 /* called with rcu_read_lock */
 109 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 110 {
 111         if (to && should_deliver(to, skb)) {
 112                 __br_deliver(to, skb);
 113                 return;
 114         }
 115
 116         kfree_skb(skb);
 117 }
 118
 119 /* called with rcu_read_lock */
 120 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
 121 {
 122         if (should_deliver(to, skb)) {
 123                 if (skb0)
 124                         deliver_clone(to, skb, __br_forward);
 125                 else
 126                         __br_forward(to, skb);
 127                 return;
 128         }
 129
 130         if (!skb0)
 131                 kfree_skb(skb);
 132 }
 133
 134 static int deliver_clone(const struct net_bridge_port *prev,
 135                          struct sk_buff *skb,
 136                          void (*__packet_hook)(const struct net_bridge_port *p,
 137                                                struct sk_buff *skb))
 138 {
 139         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 140
 141         skb = skb_clone(skb, GFP_ATOMIC);
 142         if (!skb) {
 143                 dev->stats.tx_dropped++;
 144                 return -ENOMEM;
 145         }
 146
 147         __packet_hook(prev, skb);
 148         return 0;
 149 }
 150
 151 static struct net_bridge_port *maybe_deliver(
 152         struct net_bridge_port *prev, struct net_bridge_port *p,
 153         struct sk_buff *skb,
 154         void (*__packet_hook)(const struct net_bridge_port *p,
 155                               struct sk_buff *skb))
 156 {
 157         int err;
 158
 159         if (!should_deliver(p, skb))
 160                 return prev;
 161
 162         if (!prev)
 163                 goto out;
 164
 165         err = deliver_clone(prev, skb, __packet_hook);
 166         if (err)
 167                 return ERR_PTR(err);
 168
 169 out:
 170         return p;
 171 }
 172
 173 /* called under bridge lock */
 174 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 175                      struct sk_buff *skb0,
 176                      void (*__packet_hook)(const struct net_bridge_port *p,
 177                                            struct sk_buff *skb),
 178                      bool unicast)
 179 {
 180         struct net_bridge_port *p;
 181         struct net_bridge_port *prev;
 182
 183         prev = NULL;
 184
 185         list_for_each_entry_rcu(p, &br->port_list, list) {
 186                 /* Do not flood unicast traffic to ports that turn it off */
 187                 if (unicast && !(p->flags & BR_FLOOD))
 188                         continue;
 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, bool unicast)
 211 {
 212         br_flood(br, skb, NULL, __br_deliver, unicast);
 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, bool unicast)
 218 {
 219         br_flood(br, skb, skb2, __br_forward, unicast);
 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(hlist_first_rcu(&br->router_list));
 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(hlist_next_rcu(rp));
 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