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 sock *sk, struct sk_buff *skb)
  39 {
  40         if (!is_skb_forwardable(skb->dev, skb))
  41                 goto drop;
  42
  43         skb_push(skb, ETH_HLEN);
  44         br_drop_fake_rtable(skb);
  45         skb_sender_cpu_clear(skb);
  46
  47         if (skb->ip_summed == CHECKSUM_PARTIAL &&
  48             (skb->protocol == htons(ETH_P_8021Q) ||
  49              skb->protocol == htons(ETH_P_8021AD))) {
  50                 int depth;
  51
  52                 if (!__vlan_get_protocol(skb, skb->protocol, &depth))
  53                         goto drop;
  54
  55                 skb_set_network_header(skb, depth);
  56         }
  57
  58         dev_queue_xmit(skb);
  59
  60         return 0;
  61
  62 drop:
  63         kfree_skb(skb);
  64         return 0;
  65 }
  66 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
  67
  68 int br_forward_finish(struct sock *sk, struct sk_buff *skb)
  69 {
  70         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, sk, skb,
  71                        NULL, skb->dev,
  72                        br_dev_queue_push_xmit);
  73
  74 }
  75 EXPORT_SYMBOL_GPL(br_forward_finish);
  76
  77 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  78 {
  79         skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
  80         if (!skb)
  81                 return;
  82
  83         skb->dev = to->dev;
  84
  85         if (unlikely(netpoll_tx_running(to->br->dev))) {
  86                 if (!is_skb_forwardable(skb->dev, skb))
  87                         kfree_skb(skb);
  88                 else {
  89                         skb_push(skb, ETH_HLEN);
  90                         br_netpoll_send_skb(to, skb);
  91                 }
  92                 return;
  93         }
  94
  95         NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, NULL, skb,
  96                 NULL, skb->dev,
  97                 br_forward_finish);
  98 }
  99
 100 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
 101 {
 102         struct net_device *indev;
 103
 104         if (skb_warn_if_lro(skb)) {
 105                 kfree_skb(skb);
 106                 return;
 107         }
 108
 109         skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
 110         if (!skb)
 111                 return;
 112
 113         indev = skb->dev;
 114         skb->dev = to->dev;
 115         skb_forward_csum(skb);
 116
 117         NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, NULL, skb,
 118                 indev, skb->dev,
 119                 br_forward_finish);
 120 }
 121
 122 /* called with rcu_read_lock */
 123 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 124 {
 125         if (to && should_deliver(to, skb)) {
 126                 __br_deliver(to, skb);
 127                 return;
 128         }
 129
 130         kfree_skb(skb);
 131 }
 132 EXPORT_SYMBOL_GPL(br_deliver);
 133
 134 /* called with rcu_read_lock */
 135 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
 136 {
 137         if (should_deliver(to, skb)) {
 138                 if (skb0)
 139                         deliver_clone(to, skb, __br_forward);
 140                 else
 141                         __br_forward(to, skb);
 142                 return;
 143         }
 144
 145         if (!skb0)
 146                 kfree_skb(skb);
 147 }
 148
 149 static int deliver_clone(const struct net_bridge_port *prev,
 150                          struct sk_buff *skb,
 151                          void (*__packet_hook)(const struct net_bridge_port *p,
 152                                                struct sk_buff *skb))
 153 {
 154         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 155
 156         skb = skb_clone(skb, GFP_ATOMIC);
 157         if (!skb) {
 158                 dev->stats.tx_dropped++;
 159                 return -ENOMEM;
 160         }
 161
 162         __packet_hook(prev, skb);
 163         return 0;
 164 }
 165
 166 static struct net_bridge_port *maybe_deliver(
 167         struct net_bridge_port *prev, struct net_bridge_port *p,
 168         struct sk_buff *skb,
 169         void (*__packet_hook)(const struct net_bridge_port *p,
 170                               struct sk_buff *skb))
 171 {
 172         int err;
 173
 174         if (!should_deliver(p, skb))
 175                 return prev;
 176
 177         if (!prev)
 178                 goto out;
 179
 180         err = deliver_clone(prev, skb, __packet_hook);
 181         if (err)
 182                 return ERR_PTR(err);
 183
 184 out:
 185         return p;
 186 }
 187
 188 /* called under bridge lock */
 189 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 190                      struct sk_buff *skb0,
 191                      void (*__packet_hook)(const struct net_bridge_port *p,
 192                                            struct sk_buff *skb),
 193                      bool unicast)
 194 {
 195         struct net_bridge_port *p;
 196         struct net_bridge_port *prev;
 197
 198         prev = NULL;
 199
 200         list_for_each_entry_rcu(p, &br->port_list, list) {
 201                 /* Do not flood unicast traffic to ports that turn it off */
 202                 if (unicast && !(p->flags & BR_FLOOD))
 203                         continue;
 204
 205                 /* Do not flood to ports that enable proxy ARP */
 206                 if (p->flags & BR_PROXYARP)
 207                         continue;
 208                 if ((p->flags & BR_PROXYARP_WIFI) &&
 209                     BR_INPUT_SKB_CB(skb)->proxyarp_replied)
 210                         continue;
 211
 212                 prev = maybe_deliver(prev, p, skb, __packet_hook);
 213                 if (IS_ERR(prev))
 214                         goto out;
 215         }
 216
 217         if (!prev)
 218                 goto out;
 219
 220         if (skb0)
 221                 deliver_clone(prev, skb, __packet_hook);
 222         else
 223                 __packet_hook(prev, skb);
 224         return;
 225
 226 out:
 227         if (!skb0)
 228                 kfree_skb(skb);
 229 }
 230
 231
 232 /* called with rcu_read_lock */
 233 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast)
 234 {
 235         br_flood(br, skb, NULL, __br_deliver, unicast);
 236 }
 237
 238 /* called under bridge lock */
 239 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
 240                       struct sk_buff *skb2, bool unicast)
 241 {
 242         br_flood(br, skb, skb2, __br_forward, unicast);
 243 }
 244
 245 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 246 /* called with rcu_read_lock */
 247 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 248                                struct sk_buff *skb, struct sk_buff *skb0,
 249                                void (*__packet_hook)(
 250                                         const struct net_bridge_port *p,
 251                                         struct sk_buff *skb))
 252 {
 253         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 254         struct net_bridge *br = netdev_priv(dev);
 255         struct net_bridge_port *prev = NULL;
 256         struct net_bridge_port_group *p;
 257         struct hlist_node *rp;
 258
 259         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
 260         p = mdst ? rcu_dereference(mdst->ports) : NULL;
 261         while (p || rp) {
 262                 struct net_bridge_port *port, *lport, *rport;
 263
 264                 lport = p ? p->port : NULL;
 265                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
 266                              NULL;
 267
 268                 port = (unsigned long)lport > (unsigned long)rport ?
 269                        lport : rport;
 270
 271                 prev = maybe_deliver(prev, port, skb, __packet_hook);
 272                 if (IS_ERR(prev))
 273                         goto out;
 274
 275                 if ((unsigned long)lport >= (unsigned long)port)
 276                         p = rcu_dereference(p->next);
 277                 if ((unsigned long)rport >= (unsigned long)port)
 278                         rp = rcu_dereference(hlist_next_rcu(rp));
 279         }
 280
 281         if (!prev)
 282                 goto out;
 283
 284         if (skb0)
 285                 deliver_clone(prev, skb, __packet_hook);
 286         else
 287                 __packet_hook(prev, skb);
 288         return;
 289
 290 out:
 291         if (!skb0)
 292                 kfree_skb(skb);
 293 }
 294
 295 /* called with rcu_read_lock */
 296 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
 297                           struct sk_buff *skb)
 298 {
 299         br_multicast_flood(mdst, skb, NULL, __br_deliver);
 300 }
 301
 302 /* called with rcu_read_lock */
 303 void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
 304                           struct sk_buff *skb, struct sk_buff *skb2)
 305 {
 306         br_multicast_flood(mdst, skb, skb2, __br_forward);
 307 }
 308 #endif