Pileus Git - ~andy/linux/blob - 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                 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->dev = to->dev;
  68
  69         if (unlikely(netpoll_tx_running(to->br->dev))) {
  70                 if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
  71                         kfree_skb(skb);
  72                 else {
  73                         skb_push(skb, ETH_HLEN);
  74                         br_netpoll_send_skb(to, skb);
  75                 }
  76                 return;
  77         }
  78
  79         NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  80                 br_forward_finish);
  81 }
  82
  83 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
  84 {
  85         struct net_device *indev;
  86
  87         if (skb_warn_if_lro(skb)) {
  88                 kfree_skb(skb);
  89                 return;
  90         }
  91
  92         indev = skb->dev;
  93         skb->dev = to->dev;
  94         skb_forward_csum(skb);
  95
  96         NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
  97                 br_forward_finish);
  98 }
  99
 100 /* called with rcu_read_lock */
 101 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 102 {
 103         if (to && should_deliver(to, skb)) {
 104                 __br_deliver(to, skb);
 105                 return;
 106         }
 107
 108         kfree_skb(skb);
 109 }
 110
 111 /* called with rcu_read_lock */
 112 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
 113 {
 114         if (should_deliver(to, skb)) {
 115                 if (skb0)
 116                         deliver_clone(to, skb, __br_forward);
 117                 else
 118                         __br_forward(to, skb);
 119                 return;
 120         }
 121
 122         if (!skb0)
 123                 kfree_skb(skb);
 124 }
 125
 126 static int deliver_clone(const struct net_bridge_port *prev,
 127                          struct sk_buff *skb,
 128                          void (*__packet_hook)(const struct net_bridge_port *p,
 129                                                struct sk_buff *skb))
 130 {
 131         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 132
 133         skb = skb_clone(skb, GFP_ATOMIC);
 134         if (!skb) {
 135                 dev->stats.tx_dropped++;
 136                 return -ENOMEM;
 137         }
 138
 139         __packet_hook(prev, skb);
 140         return 0;
 141 }
 142
 143 static struct net_bridge_port *maybe_deliver(
 144         struct net_bridge_port *prev, struct net_bridge_port *p,
 145         struct sk_buff *skb,
 146         void (*__packet_hook)(const struct net_bridge_port *p,
 147                               struct sk_buff *skb))
 148 {
 149         int err;
 150
 151         if (!should_deliver(p, skb))
 152                 return prev;
 153
 154         if (!prev)
 155                 goto out;
 156
 157         err = deliver_clone(prev, skb, __packet_hook);
 158         if (err)
 159                 return ERR_PTR(err);
 160
 161 out:
 162         return p;
 163 }
 164
 165 /* called under bridge lock */
 166 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 167                      struct sk_buff *skb0,
 168                      void (*__packet_hook)(const struct net_bridge_port *p,
 169                                            struct sk_buff *skb))
 170 {
 171         struct net_bridge_port *p;
 172         struct net_bridge_port *prev;
 173
 174         prev = NULL;
 175
 176         list_for_each_entry_rcu(p, &br->port_list, list) {
 177                 prev = maybe_deliver(prev, p, skb, __packet_hook);
 178                 if (IS_ERR(prev))
 179                         goto out;
 180         }
 181
 182         if (!prev)
 183                 goto out;
 184
 185         if (skb0)
 186                 deliver_clone(prev, skb, __packet_hook);
 187         else
 188                 __packet_hook(prev, skb);
 189         return;
 190
 191 out:
 192         if (!skb0)
 193                 kfree_skb(skb);
 194 }
 195
 196
 197 /* called with rcu_read_lock */
 198 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
 199 {
 200         br_flood(br, skb, NULL, __br_deliver);
 201 }
 202
 203 /* called under bridge lock */
 204 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
 205                       struct sk_buff *skb2)
 206 {
 207         br_flood(br, skb, skb2, __br_forward);
 208 }
 209
 210 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 211 /* called with rcu_read_lock */
 212 static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 213                                struct sk_buff *skb, struct sk_buff *skb0,
 214                                void (*__packet_hook)(
 215                                         const struct net_bridge_port *p,
 216                                         struct sk_buff *skb))
 217 {
 218         struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 219         struct net_bridge *br = netdev_priv(dev);
 220         struct net_bridge_port *prev = NULL;
 221         struct net_bridge_port_group *p;
 222         struct hlist_node *rp;
 223
 224         rp = rcu_dereference(hlist_first_rcu(&br->router_list));
 225         p = mdst ? rcu_dereference(mdst->ports) : NULL;
 226         while (p || rp) {
 227                 struct net_bridge_port *port, *lport, *rport;
 228
 229                 lport = p ? p->port : NULL;
 230                 rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
 231                              NULL;
 232
 233                 port = (unsigned long)lport > (unsigned long)rport ?
 234                        lport : rport;
 235
 236                 prev = maybe_deliver(prev, port, skb, __packet_hook);
 237                 if (IS_ERR(prev))
 238                         goto out;
 239
 240                 if ((unsigned long)lport >= (unsigned long)port)
 241                         p = rcu_dereference(p->next);
 242                 if ((unsigned long)rport >= (unsigned long)port)
 243                         rp = rcu_dereference(hlist_next_rcu(rp));
 244         }
 245
 246         if (!prev)
 247                 goto out;
 248
 249         if (skb0)
 250                 deliver_clone(prev, skb, __packet_hook);
 251         else
 252                 __packet_hook(prev, skb);
 253         return;
 254
 255 out:
 256         if (!skb0)
 257                 kfree_skb(skb);
 258 }
 259
 260 /* called with rcu_read_lock */
 261 void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
 262                           struct sk_buff *skb)
 263 {
 264         br_multicast_flood(mdst, skb, NULL, __br_deliver);
 265 }
 266
 267 /* called with rcu_read_lock */
 268 void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
 269                           struct sk_buff *skb, struct sk_buff *skb2)
 270 {
 271         br_multicast_flood(mdst, skb, skb2, __br_forward);
 272 }
 273 #endif