net/ipv4/netfilter/iptable_raw.c

   1 /*
   2  * 'raw' table, which is the very first hooked in at PRE_ROUTING and LOCAL_OUT .
   3  *
   4  * Copyright (C) 2003 Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
   5  */
   6 #include <linux/module.h>
   7 #include <linux/netfilter_ipv4/ip_tables.h>
   8 #include <linux/slab.h>
   9 #include <net/ip.h>
  10
  11 #define RAW_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT))
  12
  13 static const struct xt_table packet_raw = {
  14         .name = "raw",
  15         .valid_hooks =  RAW_VALID_HOOKS,
  16         .me = THIS_MODULE,
  17         .af = NFPROTO_IPV4,
  18         .priority = NF_IP_PRI_RAW,
  19 };
  20
  21 /* The work comes in here from netfilter.c. */
  22 static unsigned int
  23 iptable_raw_hook(void *priv, struct sk_buff *skb,
  24                  const struct nf_hook_state *state)
  25 {
  26         if (state->hook == NF_INET_LOCAL_OUT &&
  27             (skb->len < sizeof(struct iphdr) ||
  28              ip_hdrlen(skb) < sizeof(struct iphdr)))
  29                 /* root is playing with raw sockets. */
  30                 return NF_ACCEPT;
  31
  32         return ipt_do_table(skb, state, state->net->ipv4.iptable_raw);
  33 }
  34
  35 static struct nf_hook_ops *rawtable_ops __read_mostly;
  36
  37 static int __net_init iptable_raw_net_init(struct net *net)
  38 {
  39         struct ipt_replace *repl;
  40
  41         repl = ipt_alloc_initial_table(&packet_raw);
  42         if (repl == NULL)
  43                 return -ENOMEM;
  44         net->ipv4.iptable_raw =
  45                 ipt_register_table(net, &packet_raw, repl);
  46         kfree(repl);
  47         return PTR_ERR_OR_ZERO(net->ipv4.iptable_raw);
  48 }
  49
  50 static void __net_exit iptable_raw_net_exit(struct net *net)
  51 {
  52         ipt_unregister_table(net, net->ipv4.iptable_raw);
  53 }
  54
  55 static struct pernet_operations iptable_raw_net_ops = {
  56         .init = iptable_raw_net_init,
  57         .exit = iptable_raw_net_exit,
  58 };
  59
  60 static int __init iptable_raw_init(void)
  61 {
  62         int ret;
  63
  64         ret = register_pernet_subsys(&iptable_raw_net_ops);
  65         if (ret < 0)
  66                 return ret;
  67
  68         /* Register hooks */
  69         rawtable_ops = xt_hook_link(&packet_raw, iptable_raw_hook);
  70         if (IS_ERR(rawtable_ops)) {
  71                 ret = PTR_ERR(rawtable_ops);
  72                 unregister_pernet_subsys(&iptable_raw_net_ops);
  73         }
  74
  75         return ret;
  76 }
  77
  78 static void __exit iptable_raw_fini(void)
  79 {
  80         xt_hook_unlink(&packet_raw, rawtable_ops);
  81         unregister_pernet_subsys(&iptable_raw_net_ops);
  82 }
  83
  84 module_init(iptable_raw_init);
  85 module_exit(iptable_raw_fini);
  86 MODULE_LICENSE("GPL");