SAFE public projects git trees. - safe/jmp/linux-2.6/blob - net/ipv4/netfilter/iptable_filter.c

   1 /*
   2  * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
   3  *
   4  * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
   5  * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/netfilter_ipv4/ip_tables.h>
  16 #include <net/ip.h>
  17
  18 MODULE_LICENSE("GPL");
  19 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  20 MODULE_DESCRIPTION("iptables filter table");
  21
  22 #define FILTER_VALID_HOOKS ((1 << NF_INET_LOCAL_IN) | \
  23                             (1 << NF_INET_FORWARD) | \
  24                             (1 << NF_INET_LOCAL_OUT))
  25
  26 static struct
  27 {
  28         struct ipt_replace repl;
  29         struct ipt_standard entries[3];
  30         struct ipt_error term;
  31 } initial_table __initdata = {
  32         .repl = {
  33                 .name = "filter",
  34                 .valid_hooks = FILTER_VALID_HOOKS,
  35                 .num_entries = 4,
  36                 .size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
  37                 .hook_entry = {
  38                         [NF_INET_LOCAL_IN] = 0,
  39                         [NF_INET_FORWARD] = sizeof(struct ipt_standard),
  40                         [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2,
  41                 },
  42                 .underflow = {
  43                         [NF_INET_LOCAL_IN] = 0,
  44                         [NF_INET_FORWARD] = sizeof(struct ipt_standard),
  45                         [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2,
  46                 },
  47         },
  48         .entries = {
  49                 IPT_STANDARD_INIT(NF_ACCEPT),   /* LOCAL_IN */
  50                 IPT_STANDARD_INIT(NF_ACCEPT),   /* FORWARD */
  51                 IPT_STANDARD_INIT(NF_ACCEPT),   /* LOCAL_OUT */
  52         },
  53         .term = IPT_ERROR_INIT,                 /* ERROR */
  54 };
  55
  56 static struct xt_table __packet_filter = {
  57         .name           = "filter",
  58         .valid_hooks    = FILTER_VALID_HOOKS,
  59         .lock           = RW_LOCK_UNLOCKED,
  60         .me             = THIS_MODULE,
  61         .af             = AF_INET,
  62 };
  63 static struct xt_table *packet_filter;
  64
  65 /* The work comes in here from netfilter.c. */
  66 static unsigned int
  67 ipt_hook(unsigned int hook,
  68          struct sk_buff *skb,
  69          const struct net_device *in,
  70          const struct net_device *out,
  71          int (*okfn)(struct sk_buff *))
  72 {
  73         return ipt_do_table(skb, hook, in, out, packet_filter);
  74 }
  75
  76 static unsigned int
  77 ipt_local_out_hook(unsigned int hook,
  78                    struct sk_buff *skb,
  79                    const struct net_device *in,
  80                    const struct net_device *out,
  81                    int (*okfn)(struct sk_buff *))
  82 {
  83         /* root is playing with raw sockets. */
  84         if (skb->len < sizeof(struct iphdr) ||
  85             ip_hdrlen(skb) < sizeof(struct iphdr)) {
  86                 if (net_ratelimit())
  87                         printk("iptable_filter: ignoring short SOCK_RAW "
  88                                "packet.\n");
  89                 return NF_ACCEPT;
  90         }
  91
  92         return ipt_do_table(skb, hook, in, out, packet_filter);
  93 }
  94
  95 static struct nf_hook_ops ipt_ops[] __read_mostly = {
  96         {
  97                 .hook           = ipt_hook,
  98                 .owner          = THIS_MODULE,
  99                 .pf             = PF_INET,
 100                 .hooknum        = NF_INET_LOCAL_IN,
 101                 .priority       = NF_IP_PRI_FILTER,
 102         },
 103         {
 104                 .hook           = ipt_hook,
 105                 .owner          = THIS_MODULE,
 106                 .pf             = PF_INET,
 107                 .hooknum        = NF_INET_FORWARD,
 108                 .priority       = NF_IP_PRI_FILTER,
 109         },
 110         {
 111                 .hook           = ipt_local_out_hook,
 112                 .owner          = THIS_MODULE,
 113                 .pf             = PF_INET,
 114                 .hooknum        = NF_INET_LOCAL_OUT,
 115                 .priority       = NF_IP_PRI_FILTER,
 116         },
 117 };
 118
 119 /* Default to forward because I got too much mail already. */
 120 static int forward = NF_ACCEPT;
 121 module_param(forward, bool, 0000);
 122
 123 static int __init iptable_filter_init(void)
 124 {
 125         int ret;
 126
 127         if (forward < 0 || forward > NF_MAX_VERDICT) {
 128                 printk("iptables forward must be 0 or 1\n");
 129                 return -EINVAL;
 130         }
 131
 132         /* Entry 1 is the FORWARD hook */
 133         initial_table.entries[1].target.verdict = -forward - 1;
 134
 135         /* Register table */
 136         packet_filter = ipt_register_table(&init_net, &__packet_filter,
 137                                            &initial_table.repl);
 138         if (IS_ERR(packet_filter))
 139                 return PTR_ERR(packet_filter);
 140
 141         /* Register hooks */
 142         ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
 143         if (ret < 0)
 144                 goto cleanup_table;
 145
 146         return ret;
 147
 148  cleanup_table:
 149         ipt_unregister_table(packet_filter);
 150         return ret;
 151 }
 152
 153 static void __exit iptable_filter_fini(void)
 154 {
 155         nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
 156         ipt_unregister_table(packet_filter);
 157 }
 158
 159 module_init(iptable_filter_init);
 160 module_exit(iptable_filter_fini);