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         const struct net *net;
  53
  54         if (hook == NF_INET_LOCAL_OUT &&
  55             (skb->len < sizeof(struct iphdr) ||
  56              ip_hdrlen(skb) < sizeof(struct iphdr)))
  57                 /* root is playing with raw sockets. */
  58                 return NF_ACCEPT;
  59
  60         net = dev_net((in != NULL) ? in : out);
  61         return ipt_do_table(skb, hook, in, out, net->ipv4.iptable_raw);
  62 }
  63
  64 /* 'raw' is the very first table. */
  65 static struct nf_hook_ops ipt_ops[] __read_mostly = {
  66         {
  67                 .hook = iptable_raw_hook,
  68                 .pf = NFPROTO_IPV4,
  69                 .hooknum = NF_INET_PRE_ROUTING,
  70                 .priority = NF_IP_PRI_RAW,
  71                 .owner = THIS_MODULE,
  72         },
  73         {
  74                 .hook = iptable_raw_hook,
  75                 .pf = NFPROTO_IPV4,
  76                 .hooknum = NF_INET_LOCAL_OUT,
  77                 .priority = NF_IP_PRI_RAW,
  78                 .owner = THIS_MODULE,
  79         },
  80 };
  81
  82 static int __net_init iptable_raw_net_init(struct net *net)
  83 {
  84         /* Register table */
  85         net->ipv4.iptable_raw =
  86                 ipt_register_table(net, &packet_raw, &initial_table.repl);
  87         if (IS_ERR(net->ipv4.iptable_raw))
  88                 return PTR_ERR(net->ipv4.iptable_raw);
  89         return 0;
  90 }
  91
  92 static void __net_exit iptable_raw_net_exit(struct net *net)
  93 {
  94         ipt_unregister_table(net, net->ipv4.iptable_raw);
  95 }
  96
  97 static struct pernet_operations iptable_raw_net_ops = {
  98         .init = iptable_raw_net_init,
  99         .exit = iptable_raw_net_exit,
 100 };
 101
 102 static int __init iptable_raw_init(void)
 103 {
 104         int ret;
 105
 106         ret = register_pernet_subsys(&iptable_raw_net_ops);
 107         if (ret < 0)
 108                 return ret;
 109
 110         /* Register hooks */
 111         ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
 112         if (ret < 0)
 113                 goto cleanup_table;
 114
 115         return ret;
 116
 117  cleanup_table:
 118         unregister_pernet_subsys(&iptable_raw_net_ops);
 119         return ret;
 120 }
 121
 122 static void __exit iptable_raw_fini(void)
 123 {
 124         nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
 125         unregister_pernet_subsys(&iptable_raw_net_ops);
 126 }
 127
 128 module_init(iptable_raw_init);
 129 module_exit(iptable_raw_fini);
 130 MODULE_LICENSE("GPL");