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 <net/ip.h>
   9
  10 #define RAW_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT))
  11
  12 static const struct xt_table packet_raw = {
  13         .name = "raw",
  14         .valid_hooks =  RAW_VALID_HOOKS,
  15         .me = THIS_MODULE,
  16         .af = NFPROTO_IPV4,
  17         .priority = NF_IP_PRI_RAW,
  18 };
  19
  20 /* The work comes in here from netfilter.c. */
  21 static unsigned int
  22 iptable_raw_hook(unsigned int hook, struct sk_buff *skb,
  23                  const struct net_device *in, const struct net_device *out,
  24                  int (*okfn)(struct sk_buff *))
  25 {
  26         const struct net *net;
  27
  28         if (hook == 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((in != NULL) ? in : out);
  35         return ipt_do_table(skb, hook, in, out, 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         if (IS_ERR(net->ipv4.iptable_raw))
  51                 return PTR_ERR(net->ipv4.iptable_raw);
  52         return 0;
  53 }
  54
  55 static void __net_exit iptable_raw_net_exit(struct net *net)
  56 {
  57         ipt_unregister_table(net, net->ipv4.iptable_raw);
  58 }
  59
  60 static struct pernet_operations iptable_raw_net_ops = {
  61         .init = iptable_raw_net_init,
  62         .exit = iptable_raw_net_exit,
  63 };
  64
  65 static int __init iptable_raw_init(void)
  66 {
  67         int ret;
  68
  69         ret = register_pernet_subsys(&iptable_raw_net_ops);
  70         if (ret < 0)
  71                 return ret;
  72
  73         /* Register hooks */
  74         rawtable_ops = xt_hook_link(&packet_raw, iptable_raw_hook);
  75         if (IS_ERR(rawtable_ops)) {
  76                 ret = PTR_ERR(rawtable_ops);
  77                 goto cleanup_table;
  78         }
  79
  80         return ret;
  81
  82  cleanup_table:
  83         unregister_pernet_subsys(&iptable_raw_net_ops);
  84         return ret;
  85 }
  86
  87 static void __exit iptable_raw_fini(void)
  88 {
  89         xt_hook_unlink(&packet_raw, rawtable_ops);
  90         unregister_pernet_subsys(&iptable_raw_net_ops);
  91 }
  92
  93 module_init(iptable_raw_init);
  94 module_exit(iptable_raw_fini);
  95 MODULE_LICENSE("GPL");