net/bridge/netfilter/ebtable_broute.c

   1 /*
   2  *  ebtable_broute
   3  *
   4  *      Authors:
   5  *      Bart De Schuymer <bdschuym@pandora.be>
   6  *
   7  *  April, 2002
   8  *
   9  *  This table lets you choose between routing and bridging for frames
  10  *  entering on a bridge enslaved nic. This table is traversed before any
  11  *  other ebtables table. See net/bridge/br_input.c.
  12  */
  13
  14 #include <linux/netfilter_bridge/ebtables.h>
  15 #include <linux/module.h>
  16 #include <linux/if_bridge.h>
  17
  18 #include "../br_private.h"
  19
  20 /* EBT_ACCEPT means the frame will be bridged
  21  * EBT_DROP means the frame will be routed
  22  */
  23 static struct ebt_entries initial_chain = {
  24         .name           = "BROUTING",
  25         .policy         = EBT_ACCEPT,
  26 };
  27
  28 static struct ebt_replace_kernel initial_table = {
  29         .name           = "broute",
  30         .valid_hooks    = 1 << NF_BR_BROUTING,
  31         .entries_size   = sizeof(struct ebt_entries),
  32         .hook_entry     = {
  33                 [NF_BR_BROUTING]        = &initial_chain,
  34         },
  35         .entries        = (char *)&initial_chain,
  36 };
  37
  38 static int check(const struct ebt_table_info *info, unsigned int valid_hooks)
  39 {
  40         if (valid_hooks & ~(1 << NF_BR_BROUTING))
  41                 return -EINVAL;
  42         return 0;
  43 }
  44
  45 static const struct ebt_table broute_table = {
  46         .name           = "broute",
  47         .table          = &initial_table,
  48         .valid_hooks    = 1 << NF_BR_BROUTING,
  49         .check          = check,
  50         .me             = THIS_MODULE,
  51 };
  52
  53 static unsigned int ebt_broute(void *priv, struct sk_buff *skb,
  54                                const struct nf_hook_state *s)
  55 {
  56         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
  57         struct nf_hook_state state;
  58         unsigned char *dest;
  59         int ret;
  60
  61         if (!p || p->state != BR_STATE_FORWARDING)
  62                 return NF_ACCEPT;
  63
  64         nf_hook_state_init(&state, NF_BR_BROUTING,
  65                            NFPROTO_BRIDGE, s->in, NULL, NULL,
  66                            s->net, NULL);
  67
  68         ret = ebt_do_table(skb, &state, state.net->xt.broute_table);
  69
  70         if (ret != NF_DROP)
  71                 return ret;
  72
  73         /* DROP in ebtables -t broute means that the
  74          * skb should be routed, not bridged.
  75          * This is awkward, but can't be changed for compatibility
  76          * reasons.
  77          *
  78          * We map DROP to ACCEPT and set the ->br_netfilter_broute flag.
  79          */
  80         BR_INPUT_SKB_CB(skb)->br_netfilter_broute = 1;
  81
  82         /* undo PACKET_HOST mangling done in br_input in case the dst
  83          * address matches the logical bridge but not the port.
  84          */
  85         dest = eth_hdr(skb)->h_dest;
  86         if (skb->pkt_type == PACKET_HOST &&
  87             !ether_addr_equal(skb->dev->dev_addr, dest) &&
  88              ether_addr_equal(p->br->dev->dev_addr, dest))
  89                 skb->pkt_type = PACKET_OTHERHOST;
  90
  91         return NF_ACCEPT;
  92 }
  93
  94 static const struct nf_hook_ops ebt_ops_broute = {
  95         .hook           = ebt_broute,
  96         .pf             = NFPROTO_BRIDGE,
  97         .hooknum        = NF_BR_PRE_ROUTING,
  98         .priority       = NF_BR_PRI_FIRST,
  99 };
 100
 101 static int __net_init broute_net_init(struct net *net)
 102 {
 103         return ebt_register_table(net, &broute_table, &ebt_ops_broute,
 104                                   &net->xt.broute_table);
 105 }
 106
 107 static void __net_exit broute_net_exit(struct net *net)
 108 {
 109         ebt_unregister_table(net, net->xt.broute_table, &ebt_ops_broute);
 110 }
 111
 112 static struct pernet_operations broute_net_ops = {
 113         .init = broute_net_init,
 114         .exit = broute_net_exit,
 115 };
 116
 117 static int __init ebtable_broute_init(void)
 118 {
 119         return register_pernet_subsys(&broute_net_ops);
 120 }
 121
 122 static void __exit ebtable_broute_fini(void)
 123 {
 124         unregister_pernet_subsys(&broute_net_ops);
 125 }
 126
 127 module_init(ebtable_broute_init);
 128 module_exit(ebtable_broute_fini);
 129 MODULE_LICENSE("GPL");