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         struct net_bridge_vlan_group *vg;
  34
  35         vg = nbp_vlan_group_rcu(p);
  36         return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
  37                 br_allowed_egress(vg, skb) && p->state == BR_STATE_FORWARDING;
  38 }
  39
  40 int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
  41 {
  42         if (!is_skb_forwardable(skb->dev, skb))
  43                 goto drop;
  44
  45         skb_push(skb, ETH_HLEN);
  46         br_drop_fake_rtable(skb);
  47
  48         if (skb->ip_summed == CHECKSUM_PARTIAL &&
  49             (skb->protocol == htons(ETH_P_8021Q) ||
  50              skb->protocol == htons(ETH_P_8021AD))) {
  51                 int depth;
  52
  53                 if (!__vlan_get_protocol(skb, skb->protocol, &depth))
  54                         goto drop;
  55
  56                 skb_set_network_header(skb, depth);
  57         }
  58
  59         dev_queue_xmit(skb);
  60
  61         return 0;
  62
  63 drop:
  64         kfree_skb(skb);
  65         return 0;
  66 }
  67 EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
  68
  69 int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
  70 {
  71         return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING,
  72                        net, sk, skb, NULL, skb->dev,
  73                        br_dev_queue_push_xmit);
  74
  75 }
  76 EXPORT_SYMBOL_GPL(br_forward_finish);
  77
  78 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
  79 {
  80         struct net_bridge_vlan_group *vg;
  81
  82         vg = nbp_vlan_group_rcu(to);
  83         skb = br_handle_vlan(to->br, vg, skb);
  84         if (!skb)
  85                 return;
  86
  87         skb->dev = to->dev;
  88
  89         if (unlikely(netpoll_tx_running(to->br->dev))) {
  90                 if (!is_skb_forwardable(skb->dev, skb))
  91                         kfree_skb(skb);
  92                 else {
  93                         skb_push(skb, ETH_HLEN);
  94                         br_netpoll_send_skb(to, skb);
  95                 }
  96                 return;
  97         }
  98
  99         NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT,
 100                 dev_net(skb->dev), NULL, skb,NULL, skb->dev,
 101                 br_forward_finish);
 102 }
 103
 104 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
 105 {
 106         struct net_bridge_vlan_group *vg;
 107         struct net_device *indev;
 108
 109         if (skb_warn_if_lro(skb)) {
 110                 kfree_skb(skb);
 111                 return;
 112         }
 113
 114         vg = nbp_vlan_group_rcu(to);
 115         skb = br_handle_vlan(to->br, vg, skb);
 116         if (!skb)
 117                 return;
 118
 119         indev = skb->dev;
 120         skb->dev = to->dev;
 121         skb_forward_csum(skb);
 122
 123         NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD,
 124                 dev_net(indev), NULL, skb, indev, skb->dev,
 125                 br_forward_finish);
 126 }
 127
 128 /* called with rcu_read_lock */
 129 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 130 {
 131         if (to && should_deliver(to, skb)) {
 132                 __br_deliver(to, skb);
 133                 return;
 134         }
 135
 136         kfree_skb(skb);
 137 }
 138 EXPORT_SYMBOL_GPL(br_deliver);
 139
 140 /* called with rcu_read_lock */
 141 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
 142 {
 143         if (to && should_deliver(to, skb)) {
 144                 if (skb0)
 145                         deliver_clone(to, skb, __br_forward);
 146                 else
 147                         __br_forward(to, skb);
 148                 return;
 149         }
 150
 151         if (!skb0)
 152                 kfree_skb(skb);
 153 }
 154
 155 static int deliver_clone(const struct net_bridge_port *prev,
 156                          struct sk_buff *skb,
 157                          void (*__packet_hook)(const struct net_bridge_port *p,
 158                                                struct sk_buff *skb))
 159 {
 160         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 161
 162         skb = skb_clone(skb, GFP_ATOMIC);
 163         if (!skb) {
 164                 dev->stats.tx_dropped++;
 165                 return -ENOMEM;
 166         }
 167
 168         __packet_hook(prev, skb);
 169         return 0;
 170 }
 171
 172 static struct net_bridge_port *maybe_deliver(
 173         struct net_bridge_port *prev, struct net_bridge_port *p,
 174         struct sk_buff *skb,
 175         void (*__packet_hook)(const struct net_bridge_port *p,
 176                               struct sk_buff *skb))
 177 {
 178         int err;
 179
 180         if (!should_deliver(p, skb))
 181                 return prev;
 182
 183         if (!prev)
 184                 goto out;
 185
 186         err = deliver_clone(prev, skb, __packet_hook);
 187         if (err)
 188                 return ERR_PTR(err);
 189
 190 out:
 191         return p;
 192 }
 193
 194 /* called under bridge lock */
 195 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 196                      struct sk_buff *skb0,
 197                      void (*__packet_hook)(const struct net_bridge_port *p,
 198                                            struct sk_buff *skb),
 199                      bool unicast)
 200 {
 201         struct net_bridge_port *p;
 202         struct net_bridge_port *prev;
 203
 204         prev = NULL;
 205
 206         list_for_each_entry_rcu(p, &br->port_list, list) {
 207                 /* Do not flood unicast traffic to ports that turn it off */
 208                 if (unicast && !(p->flags & BR_FLOOD))
 209                         continue;
 210
 211                 /* Do not flood to ports that enable proxy ARP */
 212                 if (p->flags & BR_PROXYARP)
 213                         continue;
 214                 if ((p->flags & BR_PROXYARP_WIFI) &&
 215                     BR_INPUT_SKB_CB(skb)->proxyarp_replied)
 216                         continue;
 217
 218                 prev = maybe_deliver(prev, p, skb, __packet_hook);
 219                 if (IS_ERR(prev))
 220                         goto out;
 221         }
 222
 223         if (!prev)
 224                 goto out;
 225
 226         if (skb0)
 227                 deliver_clone(prev, skb, __packet_hook);
 228         else
 229                 __packet_hook(prev, skb);
 230         return;
 231
 232 out:
 233         if (!skb0)
 234                 kfree_skb(skb);
 235 }
 236
 237
 238 /* called with rcu_read_lock */
 239 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast)
 240 {
 241         br_flood(br, skb, NULL, __br_deliver, unicast);
 242 }
 243
 244 /* called under bridge lock */
 245 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
 246                       struct sk_buff *skb2, bool unicast)
 247 {
 248         br_flood(br, skb, skb2, __br_forward, unicast);
 249 }
 250
 251 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 252 /* called with rcu_read_lock */
 253 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 254                                struct sk_buff *skb, struct sk_buff *skb0,
 255                                void (*__packet_hook)(
 256                                         const struct net_bridge_port *p,
 257                                         struct sk_buff *skb))
 258 {
 259         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 260         struct net_bridge *br = netdev_priv(dev);
 261         struct net_bridge_port *prev = NULL;
 262         struct net_bridge_port_group *p;
 263         struct hlist_node *rp;
 264
 265         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
 266         p = mdst ? rcu_dereference(mdst->ports) : NULL;
 267         while (p || rp) {
 268                 struct net_bridge_port *port, *lport, *rport;
 269
 270                 lport = p ? p->port : NULL;
 271                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
 272                              NULL;
 273
 274                 port = (unsigned long)lport > (unsigned long)rport ?
 275                        lport : rport;
 276
 277                 prev = maybe_deliver(prev, port, skb, __packet_hook);
 278                 if (IS_ERR(prev))
 279                         goto out;
 280
 281                 if ((unsigned long)lport >= (unsigned long)port)
 282                         p = rcu_dereference(p->next);
 283                 if ((unsigned long)rport >= (unsigned long)port)
 284                         rp = rcu_dereference(hlist_next_rcu(rp));
 285         }
 286
 287         if (!prev)
 288                 goto out;
 289
 290         if (skb0)
 291                 deliver_clone(prev, skb, __packet_hook);
 292         else
 293                 __packet_hook(prev, skb);
 294         return;
 295
 296 out:
 297         if (!skb0)
 298                 kfree_skb(skb);
 299 }
 300
 301 /* called with rcu_read_lock */
 302 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
 303                           struct sk_buff *skb)
 304 {
 305         br_multicast_flood(mdst, skb, NULL, __br_deliver);
 306 }
 307
 308 /* called with rcu_read_lock */
 309 void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
 310                           struct sk_buff *skb, struct sk_buff *skb2)
 311 {
 312         br_multicast_flood(mdst, skb, skb2, __br_forward);
 313 }
 314 #endif