Pileus Git - ~andy/linux/blob - net/ipv4/netfilter/ipt_REJECT.c

   1 /*
   2  * This is a module which is used for rejecting packets.
   3  */
   4
   5 /* (C) 1999-2001 Paul `Rusty' Russell
   6  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13 #include <linux/module.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/slab.h>
  16 #include <linux/ip.h>
  17 #include <linux/udp.h>
  18 #include <linux/icmp.h>
  19 #include <net/icmp.h>
  20 #include <linux/netfilter/x_tables.h>
  21 #include <linux/netfilter_ipv4/ip_tables.h>
  22 #include <linux/netfilter_ipv4/ipt_REJECT.h>
  23 #ifdef CONFIG_BRIDGE_NETFILTER
  24 #include <linux/netfilter_bridge.h>
  25 #endif
  26
  27 #include <net/netfilter/ipv4/nf_reject.h>
  28
  29 MODULE_LICENSE("GPL");
  30 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  31 MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv4");
  32
  33 static unsigned int
  34 reject_tg(struct sk_buff *skb, const struct xt_action_param *par)
  35 {
  36         const struct ipt_reject_info *reject = par->targinfo;
  37
  38         switch (reject->with) {
  39         case IPT_ICMP_NET_UNREACHABLE:
  40                 nf_send_unreach(skb, ICMP_NET_UNREACH);
  41                 break;
  42         case IPT_ICMP_HOST_UNREACHABLE:
  43                 nf_send_unreach(skb, ICMP_HOST_UNREACH);
  44                 break;
  45         case IPT_ICMP_PROT_UNREACHABLE:
  46                 nf_send_unreach(skb, ICMP_PROT_UNREACH);
  47                 break;
  48         case IPT_ICMP_PORT_UNREACHABLE:
  49                 nf_send_unreach(skb, ICMP_PORT_UNREACH);
  50                 break;
  51         case IPT_ICMP_NET_PROHIBITED:
  52                 nf_send_unreach(skb, ICMP_NET_ANO);
  53                 break;
  54         case IPT_ICMP_HOST_PROHIBITED:
  55                 nf_send_unreach(skb, ICMP_HOST_ANO);
  56                 break;
  57         case IPT_ICMP_ADMIN_PROHIBITED:
  58                 nf_send_unreach(skb, ICMP_PKT_FILTERED);
  59                 break;
  60         case IPT_TCP_RESET:
  61                 nf_send_reset(skb, par->hooknum);
  62         case IPT_ICMP_ECHOREPLY:
  63                 /* Doesn't happen. */
  64                 break;
  65         }
  66
  67         return NF_DROP;
  68 }
  69
  70 static int reject_tg_check(const struct xt_tgchk_param *par)
  71 {
  72         const struct ipt_reject_info *rejinfo = par->targinfo;
  73         const struct ipt_entry *e = par->entryinfo;
  74
  75         if (rejinfo->with == IPT_ICMP_ECHOREPLY) {
  76                 pr_info("ECHOREPLY no longer supported.\n");
  77                 return -EINVAL;
  78         } else if (rejinfo->with == IPT_TCP_RESET) {
  79                 /* Must specify that it's a TCP packet */
  80                 if (e->ip.proto != IPPROTO_TCP ||
  81                     (e->ip.invflags & XT_INV_PROTO)) {
  82                         pr_info("TCP_RESET invalid for non-tcp\n");
  83                         return -EINVAL;
  84                 }
  85         }
  86         return 0;
  87 }
  88
  89 static struct xt_target reject_tg_reg __read_mostly = {
  90         .name           = "REJECT",
  91         .family         = NFPROTO_IPV4,
  92         .target         = reject_tg,
  93         .targetsize     = sizeof(struct ipt_reject_info),
  94         .table          = "filter",
  95         .hooks          = (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD) |
  96                           (1 << NF_INET_LOCAL_OUT),
  97         .checkentry     = reject_tg_check,
  98         .me             = THIS_MODULE,
  99 };
 100
 101 static int __init reject_tg_init(void)
 102 {
 103         return xt_register_target(&reject_tg_reg);
 104 }
 105
 106 static void __exit reject_tg_exit(void)
 107 {
 108         xt_unregister_target(&reject_tg_reg);
 109 }
 110
 111 module_init(reject_tg_init);
 112 module_exit(reject_tg_exit);