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(const struct nf_hook_ops *ops, struct sk_buff *skb,
  24                  const struct nf_hook_state *state)
  25 {
  26         const struct net *net;
  27
  28         if (ops->hooknum == NF_INET_LOCAL_OUT &&
  29             (skb->len < sizeof(struct iphdr) ||
  30              ip_hdrlen(skb) < sizeof(struct iphdr)))
  31                 /* root is playing with raw sockets. */
  32                 return NF_ACCEPT;
  33
  34         net = dev_net(state->in ? state->in : state->out);
  35         return ipt_do_table(skb, ops->hooknum, state, net->ipv4.iptable_raw);
  36 }
  37
  38 static struct nf_hook_ops *rawtable_ops __read_mostly;
  39
  40 static int __net_init iptable_raw_net_init(struct net *net)
  41 {
  42         struct ipt_replace *repl;
  43
  44         repl = ipt_alloc_initial_table(&packet_raw);
  45         if (repl == NULL)
  46                 return -ENOMEM;
  47         net->ipv4.iptable_raw =
  48                 ipt_register_table(net, &packet_raw, repl);
  49         kfree(repl);
  50         return PTR_ERR_OR_ZERO(net->ipv4.iptable_raw);
  51 }
  52
  53 static void __net_exit iptable_raw_net_exit(struct net *net)
  54 {
  55         ipt_unregister_table(net, net->ipv4.iptable_raw);
  56 }
  57
  58 static struct pernet_operations iptable_raw_net_ops = {
  59         .init = iptable_raw_net_init,
  60         .exit = iptable_raw_net_exit,
  61 };
  62
  63 static int __init iptable_raw_init(void)
  64 {
  65         int ret;
  66
  67         ret = register_pernet_subsys(&iptable_raw_net_ops);
  68         if (ret < 0)
  69                 return ret;
  70
  71         /* Register hooks */
  72         rawtable_ops = xt_hook_link(&packet_raw, iptable_raw_hook);
  73         if (IS_ERR(rawtable_ops)) {
  74                 ret = PTR_ERR(rawtable_ops);
  75                 unregister_pernet_subsys(&iptable_raw_net_ops);
  76         }
  77
  78         return ret;
  79 }
  80
  81 static void __exit iptable_raw_fini(void)
  82 {
  83         xt_hook_unlink(&packet_raw, rawtable_ops);
  84         unregister_pernet_subsys(&iptable_raw_net_ops);
  85 }
  86
  87 module_init(iptable_raw_init);
  88 module_exit(iptable_raw_fini);
  89 MODULE_LICENSE("GPL");