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 int __net_init iptable_raw_table_init(struct net *net);
  14
  15 static const struct xt_table packet_raw = {
  16         .name = "raw",
  17         .valid_hooks =  RAW_VALID_HOOKS,
  18         .me = THIS_MODULE,
  19         .af = NFPROTO_IPV4,
  20         .priority = NF_IP_PRI_RAW,
  21         .table_init = iptable_raw_table_init,
  22 };
  23
  24 /* The work comes in here from netfilter.c. */
  25 static unsigned int
  26 iptable_raw_hook(void *priv, struct sk_buff *skb,
  27                  const struct nf_hook_state *state)
  28 {
  29         if (state->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         return ipt_do_table(skb, state, 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_table_init(struct net *net)
  41 {
  42         struct ipt_replace *repl;
  43         int ret;
  44
  45         if (net->ipv4.iptable_raw)
  46                 return 0;
  47
  48         repl = ipt_alloc_initial_table(&packet_raw);
  49         if (repl == NULL)
  50                 return -ENOMEM;
  51         ret = ipt_register_table(net, &packet_raw, repl, rawtable_ops,
  52                                  &net->ipv4.iptable_raw);
  53         kfree(repl);
  54         return ret;
  55 }
  56
  57 static void __net_exit iptable_raw_net_exit(struct net *net)
  58 {
  59         if (!net->ipv4.iptable_raw)
  60                 return;
  61         ipt_unregister_table(net, net->ipv4.iptable_raw, rawtable_ops);
  62         net->ipv4.iptable_raw = NULL;
  63 }
  64
  65 static struct pernet_operations iptable_raw_net_ops = {
  66         .exit = iptable_raw_net_exit,
  67 };
  68
  69 static int __init iptable_raw_init(void)
  70 {
  71         int ret;
  72
  73         rawtable_ops = xt_hook_ops_alloc(&packet_raw, iptable_raw_hook);
  74         if (IS_ERR(rawtable_ops))
  75                 return PTR_ERR(rawtable_ops);
  76
  77         ret = register_pernet_subsys(&iptable_raw_net_ops);
  78         if (ret < 0) {
  79                 kfree(rawtable_ops);
  80                 return ret;
  81         }
  82
  83         ret = iptable_raw_table_init(&init_net);
  84         if (ret) {
  85                 unregister_pernet_subsys(&iptable_raw_net_ops);
  86                 kfree(rawtable_ops);
  87         }
  88
  89         return ret;
  90 }
  91
  92 static void __exit iptable_raw_fini(void)
  93 {
  94         unregister_pernet_subsys(&iptable_raw_net_ops);
  95         kfree(rawtable_ops);
  96 }
  97
  98 module_init(iptable_raw_init);
  99 module_exit(iptable_raw_fini);
 100 MODULE_LICENSE("GPL");