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 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 struct xt_table packet_raw = {
  40         .name = "raw",
  41         .valid_hooks =  RAW_VALID_HOOKS,
  42         .lock = RW_LOCK_UNLOCKED,
  43         .me = THIS_MODULE,
  44         .af = AF_INET,
  45 };
  46
  47 /* The work comes in here from netfilter.c. */
  48 static unsigned int
  49 ipt_hook(unsigned int hook,
  50          struct sk_buff *skb,
  51          const struct net_device *in,
  52          const struct net_device *out,
  53          int (*okfn)(struct sk_buff *))
  54 {
  55         return ipt_do_table(skb, hook, in, out, init_net.ipv4.iptable_raw);
  56 }
  57
  58 static unsigned int
  59 ipt_local_hook(unsigned int hook,
  60                struct sk_buff *skb,
  61                const struct net_device *in,
  62                const struct net_device *out,
  63                int (*okfn)(struct sk_buff *))
  64 {
  65         /* root is playing with raw sockets. */
  66         if (skb->len < sizeof(struct iphdr) ||
  67             ip_hdrlen(skb) < sizeof(struct iphdr)) {
  68                 if (net_ratelimit())
  69                         printk("iptable_raw: ignoring short SOCK_RAW "
  70                                "packet.\n");
  71                 return NF_ACCEPT;
  72         }
  73         return ipt_do_table(skb, hook, in, out, init_net.ipv4.iptable_raw);
  74 }
  75
  76 /* 'raw' is the very first table. */
  77 static struct nf_hook_ops ipt_ops[] __read_mostly = {
  78         {
  79                 .hook = ipt_hook,
  80                 .pf = PF_INET,
  81                 .hooknum = NF_INET_PRE_ROUTING,
  82                 .priority = NF_IP_PRI_RAW,
  83                 .owner = THIS_MODULE,
  84         },
  85         {
  86                 .hook = ipt_local_hook,
  87                 .pf = PF_INET,
  88                 .hooknum = NF_INET_LOCAL_OUT,
  89                 .priority = NF_IP_PRI_RAW,
  90                 .owner = THIS_MODULE,
  91         },
  92 };
  93
  94 static int __net_init iptable_raw_net_init(struct net *net)
  95 {
  96         /* Register table */
  97         net->ipv4.iptable_raw =
  98                 ipt_register_table(net, &packet_raw, &initial_table.repl);
  99         if (IS_ERR(net->ipv4.iptable_raw))
 100                 return PTR_ERR(net->ipv4.iptable_raw);
 101         return 0;
 102 }
 103
 104 static void __net_exit iptable_raw_net_exit(struct net *net)
 105 {
 106         ipt_unregister_table(net->ipv4.iptable_raw);
 107 }
 108
 109 static struct pernet_operations iptable_raw_net_ops = {
 110         .init = iptable_raw_net_init,
 111         .exit = iptable_raw_net_exit,
 112 };
 113
 114 static int __init iptable_raw_init(void)
 115 {
 116         int ret;
 117
 118         ret = register_pernet_subsys(&iptable_raw_net_ops);
 119         if (ret < 0)
 120                 return ret;
 121
 122         /* Register hooks */
 123         ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
 124         if (ret < 0)
 125                 goto cleanup_table;
 126
 127         return ret;
 128
 129  cleanup_table:
 130         unregister_pernet_subsys(&iptable_raw_net_ops);
 131         return ret;
 132 }
 133
 134 static void __exit iptable_raw_fini(void)
 135 {
 136         nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
 137         unregister_pernet_subsys(&iptable_raw_net_ops);
 138 }
 139
 140 module_init(iptable_raw_init);
 141 module_exit(iptable_raw_fini);
 142 MODULE_LICENSE("GPL");