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
  13 {
  14         struct ipt_replace repl;
  15         struct ipt_standard entries[2];
  16         struct ipt_error term;
  17 } initial_table __net_initdata = {
  18         .repl = {
  19                 .name = "raw",
  20                 .valid_hooks = RAW_VALID_HOOKS,
  21                 .num_entries = 3,
  22                 .size = sizeof(struct ipt_standard) * 2 + sizeof(struct ipt_error),
  23                 .hook_entry = {
  24                         [NF_INET_PRE_ROUTING] = 0,
  25                         [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard)
  26                 },
  27                 .underflow = {
  28                         [NF_INET_PRE_ROUTING] = 0,
  29                         [NF_INET_LOCAL_OUT]  = sizeof(struct ipt_standard)
  30                 },
  31         },
  32         .entries = {
  33                 IPT_STANDARD_INIT(NF_ACCEPT),   /* PRE_ROUTING */
  34                 IPT_STANDARD_INIT(NF_ACCEPT),   /* LOCAL_OUT */
  35         },
  36         .term = IPT_ERROR_INIT,                 /* ERROR */
  37 };
  38
  39 static const struct xt_table packet_raw = {
  40         .name = "raw",
  41         .valid_hooks =  RAW_VALID_HOOKS,
  42         .me = THIS_MODULE,
  43         .af = NFPROTO_IPV4,
  44 };
  45
  46 /* The work comes in here from netfilter.c. */
  47 static unsigned int
  48 iptable_raw_hook(unsigned int hook, struct sk_buff *skb,
  49                  const struct net_device *in, const struct net_device *out,
  50                  int (*okfn)(struct sk_buff *))
  51 {
  52         if (hook == NF_INET_PRE_ROUTING)
  53                 return ipt_do_table(skb, hook, in, out,
  54                                     dev_net(in)->ipv4.iptable_raw);
  55
  56         /* OUTPUT: */
  57         /* root is playing with raw sockets. */
  58         if (skb->len < sizeof(struct iphdr) ||
  59             ip_hdrlen(skb) < sizeof(struct iphdr))
  60                 return NF_ACCEPT;
  61         return ipt_do_table(skb, hook, in, out,
  62                             dev_net(out)->ipv4.iptable_raw);
  63 }
  64
  65 /* 'raw' is the very first table. */
  66 static struct nf_hook_ops ipt_ops[] __read_mostly = {
  67         {
  68                 .hook = iptable_raw_hook,
  69                 .pf = NFPROTO_IPV4,
  70                 .hooknum = NF_INET_PRE_ROUTING,
  71                 .priority = NF_IP_PRI_RAW,
  72                 .owner = THIS_MODULE,
  73         },
  74         {
  75                 .hook = iptable_raw_hook,
  76                 .pf = NFPROTO_IPV4,
  77                 .hooknum = NF_INET_LOCAL_OUT,
  78                 .priority = NF_IP_PRI_RAW,
  79                 .owner = THIS_MODULE,
  80         },
  81 };
  82
  83 static int __net_init iptable_raw_net_init(struct net *net)
  84 {
  85         /* Register table */
  86         net->ipv4.iptable_raw =
  87                 ipt_register_table(net, &packet_raw, &initial_table.repl);
  88         if (IS_ERR(net->ipv4.iptable_raw))
  89                 return PTR_ERR(net->ipv4.iptable_raw);
  90         return 0;
  91 }
  92
  93 static void __net_exit iptable_raw_net_exit(struct net *net)
  94 {
  95         ipt_unregister_table(net, net->ipv4.iptable_raw);
  96 }
  97
  98 static struct pernet_operations iptable_raw_net_ops = {
  99         .init = iptable_raw_net_init,
 100         .exit = iptable_raw_net_exit,
 101 };
 102
 103 static int __init iptable_raw_init(void)
 104 {
 105         int ret;
 106
 107         ret = register_pernet_subsys(&iptable_raw_net_ops);
 108         if (ret < 0)
 109                 return ret;
 110
 111         /* Register hooks */
 112         ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
 113         if (ret < 0)
 114                 goto cleanup_table;
 115
 116         return ret;
 117
 118  cleanup_table:
 119         unregister_pernet_subsys(&iptable_raw_net_ops);
 120         return ret;
 121 }
 122
 123 static void __exit iptable_raw_fini(void)
 124 {
 125         nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
 126         unregister_pernet_subsys(&iptable_raw_net_ops);
 127 }
 128
 129 module_init(iptable_raw_init);
 130 module_exit(iptable_raw_fini);
 131 MODULE_LICENSE("GPL");