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(unsigned int hook, struct sk_buff *skb,
  24                  const struct net_device *in, const struct net_device *out,
  25                  int (*okfn)(struct sk_buff *))
  26 {
  27         const struct net *net;
  28
  29         if (hook == NF_INET_LOCAL_OUT &&
  30             (skb->len < sizeof(struct iphdr) ||
  31              ip_hdrlen(skb) < sizeof(struct iphdr)))
  32                 /* root is playing with raw sockets. */
  33                 return NF_ACCEPT;
  34
  35         net = dev_net((in != NULL) ? in : out);
  36         return ipt_do_table(skb, hook, in, out, net->ipv4.iptable_raw);
  37 }
  38
  39 static struct nf_hook_ops *rawtable_ops __read_mostly;
  40
  41 static int __net_init iptable_raw_net_init(struct net *net)
  42 {
  43         struct ipt_replace *repl;
  44
  45         repl = ipt_alloc_initial_table(&packet_raw);
  46         if (repl == NULL)
  47                 return -ENOMEM;
  48         net->ipv4.iptable_raw =
  49                 ipt_register_table(net, &packet_raw, repl);
  50         kfree(repl);
  51         if (IS_ERR(net->ipv4.iptable_raw))
  52                 return PTR_ERR(net->ipv4.iptable_raw);
  53         return 0;
  54 }
  55
  56 static void __net_exit iptable_raw_net_exit(struct net *net)
  57 {
  58         ipt_unregister_table(net, net->ipv4.iptable_raw);
  59 }
  60
  61 static struct pernet_operations iptable_raw_net_ops = {
  62         .init = iptable_raw_net_init,
  63         .exit = iptable_raw_net_exit,
  64 };
  65
  66 static int __init iptable_raw_init(void)
  67 {
  68         int ret;
  69
  70         ret = register_pernet_subsys(&iptable_raw_net_ops);
  71         if (ret < 0)
  72                 return ret;
  73
  74         /* Register hooks */
  75         rawtable_ops = xt_hook_link(&packet_raw, iptable_raw_hook);
  76         if (IS_ERR(rawtable_ops)) {
  77                 ret = PTR_ERR(rawtable_ops);
  78                 goto cleanup_table;
  79         }
  80
  81         return ret;
  82
  83  cleanup_table:
  84         unregister_pernet_subsys(&iptable_raw_net_ops);
  85         return ret;
  86 }
  87
  88 static void __exit iptable_raw_fini(void)
  89 {
  90         xt_hook_unlink(&packet_raw, rawtable_ops);
  91         unregister_pernet_subsys(&iptable_raw_net_ops);
  92 }
  93
  94 module_init(iptable_raw_init);
  95 module_exit(iptable_raw_fini);
  96 MODULE_LICENSE("GPL");