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 int br_dev_queue_push_xmit(struct sk_buff *skb)
  39 {
  40         /* ip_fragment doesn't copy the MAC header */
  41         if (nf_bridge_maybe_copy_header(skb) ||
  42             !is_skb_forwardable(skb->dev, skb)) {
  43                 kfree_skb(skb);
  44         } else {
  45                 skb_push(skb, ETH_HLEN);
  46                 br_drop_fake_rtable(skb);
  47                 dev_queue_xmit(skb);
  48         }
  49
  50         return 0;
  51 }
  52
  53 int br_forward_finish(struct sk_buff *skb)
  54 {
  55         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  56                        br_dev_queue_push_xmit);
  57
  58 }
  59
  60 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  61 {
  62         skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
  63         if (!skb)
  64                 return;
  65
  66         skb->dev = to->dev;
  67
  68         if (unlikely(netpoll_tx_running(to->br->dev))) {
  69                 if (!is_skb_forwardable(skb->dev, 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         skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
  92         if (!skb)
  93                 return;
  94
  95         indev = skb->dev;
  96         skb->dev = to->dev;
  97         skb_forward_csum(skb);
  98
  99         NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
 100                 br_forward_finish);
 101 }
 102
 103 /* called with rcu_read_lock */
 104 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 105 {
 106         if (to && should_deliver(to, skb)) {
 107                 __br_deliver(to, skb);
 108                 return;
 109         }
 110
 111         kfree_skb(skb);
 112 }
 113
 114 /* called with rcu_read_lock */
 115 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
 116 {
 117         if (should_deliver(to, skb)) {
 118                 if (skb0)
 119                         deliver_clone(to, skb, __br_forward);
 120                 else
 121                         __br_forward(to, skb);
 122                 return;
 123         }
 124
 125         if (!skb0)
 126                 kfree_skb(skb);
 127 }
 128
 129 static int deliver_clone(const struct net_bridge_port *prev,
 130                          struct sk_buff *skb,
 131                          void (*__packet_hook)(const struct net_bridge_port *p,
 132                                                struct sk_buff *skb))
 133 {
 134         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 135
 136         skb = skb_clone(skb, GFP_ATOMIC);
 137         if (!skb) {
 138                 dev->stats.tx_dropped++;
 139                 return -ENOMEM;
 140         }
 141
 142         __packet_hook(prev, skb);
 143         return 0;
 144 }
 145
 146 static struct net_bridge_port *maybe_deliver(
 147         struct net_bridge_port *prev, struct net_bridge_port *p,
 148         struct sk_buff *skb,
 149         void (*__packet_hook)(const struct net_bridge_port *p,
 150                               struct sk_buff *skb))
 151 {
 152         int err;
 153
 154         if (!should_deliver(p, skb))
 155                 return prev;
 156
 157         if (!prev)
 158                 goto out;
 159
 160         err = deliver_clone(prev, skb, __packet_hook);
 161         if (err)
 162                 return ERR_PTR(err);
 163
 164 out:
 165         return p;
 166 }
 167
 168 /* called under bridge lock */
 169 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 170                      struct sk_buff *skb0,
 171                      void (*__packet_hook)(const struct net_bridge_port *p,
 172                                            struct sk_buff *skb),
 173                      bool unicast)
 174 {
 175         struct net_bridge_port *p;
 176         struct net_bridge_port *prev;
 177
 178         prev = NULL;
 179
 180         list_for_each_entry_rcu(p, &br->port_list, list) {
 181                 /* Do not flood unicast traffic to ports that turn it off */
 182                 if (unicast && !(p->flags & BR_FLOOD))
 183                         continue;
 184                 prev = maybe_deliver(prev, p, skb, __packet_hook);
 185                 if (IS_ERR(prev))
 186                         goto out;
 187         }
 188
 189         if (!prev)
 190                 goto out;
 191
 192         if (skb0)
 193                 deliver_clone(prev, skb, __packet_hook);
 194         else
 195                 __packet_hook(prev, skb);
 196         return;
 197
 198 out:
 199         if (!skb0)
 200                 kfree_skb(skb);
 201 }
 202
 203
 204 /* called with rcu_read_lock */
 205 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast)
 206 {
 207         br_flood(br, skb, NULL, __br_deliver, unicast);
 208 }
 209
 210 /* called under bridge lock */
 211 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
 212                       struct sk_buff *skb2, bool unicast)
 213 {
 214         br_flood(br, skb, skb2, __br_forward, unicast);
 215 }
 216
 217 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 218 /* called with rcu_read_lock */
 219 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 220                                struct sk_buff *skb, struct sk_buff *skb0,
 221                                void (*__packet_hook)(
 222                                         const struct net_bridge_port *p,
 223                                         struct sk_buff *skb))
 224 {
 225         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 226         struct net_bridge *br = netdev_priv(dev);
 227         struct net_bridge_port *prev = NULL;
 228         struct net_bridge_port_group *p;
 229         struct hlist_node *rp;
 230
 231         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
 232         p = mdst ? rcu_dereference(mdst->ports) : NULL;
 233         while (p || rp) {
 234                 struct net_bridge_port *port, *lport, *rport;
 235
 236                 lport = p ? p->port : NULL;
 237                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
 238                              NULL;
 239
 240                 port = (unsigned long)lport > (unsigned long)rport ?
 241                        lport : rport;
 242
 243                 prev = maybe_deliver(prev, port, skb, __packet_hook);
 244                 if (IS_ERR(prev))
 245                         goto out;
 246
 247                 if ((unsigned long)lport >= (unsigned long)port)
 248                         p = rcu_dereference(p->next);
 249                 if ((unsigned long)rport >= (unsigned long)port)
 250                         rp = rcu_dereference(hlist_next_rcu(rp));
 251         }
 252
 253         if (!prev)
 254                 goto out;
 255
 256         if (skb0)
 257                 deliver_clone(prev, skb, __packet_hook);
 258         else
 259                 __packet_hook(prev, skb);
 260         return;
 261
 262 out:
 263         if (!skb0)
 264                 kfree_skb(skb);
 265 }
 266
 267 /* called with rcu_read_lock */
 268 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
 269                           struct sk_buff *skb)
 270 {
 271         br_multicast_flood(mdst, skb, NULL, __br_deliver);
 272 }
 273
 274 /* called with rcu_read_lock */
 275 void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
 276                           struct sk_buff *skb, struct sk_buff *skb2)
 277 {
 278         br_multicast_flood(mdst, skb, skb2, __br_forward);
 279 }
 280 #endif