net/ipv4/netfilter/ipt_addrtype.c

   1 /*
   2  *  iptables module to match inet_addr_type() of an ip.
   3  *
   4  *  Copyright (c) 2004 Patrick McHardy <kaber@trash.net>
   5  *  (C) 2007 Laszlo Attila Toth <panther@balabit.hu>
   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 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/netdevice.h>
  16 #include <linux/ip.h>
  17 #include <net/route.h>
  18
  19 #include <linux/netfilter_ipv4/ipt_addrtype.h>
  20 #include <linux/netfilter/x_tables.h>
  21
  22 MODULE_LICENSE("GPL");
  23 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  24 MODULE_DESCRIPTION("Xtables: address type match for IPv4");
  25
  26 static inline bool match_type(const struct net_device *dev, __be32 addr,
  27                               u_int16_t mask)
  28 {
  29         return !!(mask & (1 << inet_dev_addr_type(&init_net, dev, addr)));
  30 }
  31
  32 static bool
  33 addrtype_mt_v0(const struct sk_buff *skb, const struct xt_match_param *par)
  34 {
  35         const struct ipt_addrtype_info *info = par->matchinfo;
  36         const struct iphdr *iph = ip_hdr(skb);
  37         bool ret = true;
  38
  39         if (info->source)
  40                 ret &= match_type(NULL, iph->saddr, info->source) ^
  41                        info->invert_source;
  42         if (info->dest)
  43                 ret &= match_type(NULL, iph->daddr, info->dest) ^
  44                        info->invert_dest;
  45
  46         return ret;
  47 }
  48
  49 static bool
  50 addrtype_mt_v1(const struct sk_buff *skb, const struct xt_match_param *par)
  51 {
  52         const struct ipt_addrtype_info_v1 *info = par->matchinfo;
  53         const struct iphdr *iph = ip_hdr(skb);
  54         const struct net_device *dev = NULL;
  55         bool ret = true;
  56
  57         if (info->flags & IPT_ADDRTYPE_LIMIT_IFACE_IN)
  58                 dev = par->in;
  59         else if (info->flags & IPT_ADDRTYPE_LIMIT_IFACE_OUT)
  60                 dev = par->out;
  61
  62         if (info->source)
  63                 ret &= match_type(dev, iph->saddr, info->source) ^
  64                        (info->flags & IPT_ADDRTYPE_INVERT_SOURCE);
  65         if (ret && info->dest)
  66                 ret &= match_type(dev, iph->daddr, info->dest) ^
  67                        !!(info->flags & IPT_ADDRTYPE_INVERT_DEST);
  68         return ret;
  69 }
  70
  71 static bool addrtype_mt_checkentry_v1(const struct xt_mtchk_param *par)
  72 {
  73         struct ipt_addrtype_info_v1 *info = par->matchinfo;
  74
  75         if (info->flags & IPT_ADDRTYPE_LIMIT_IFACE_IN &&
  76             info->flags & IPT_ADDRTYPE_LIMIT_IFACE_OUT) {
  77                 printk(KERN_ERR "ipt_addrtype: both incoming and outgoing "
  78                                 "interface limitation cannot be selected\n");
  79                 return false;
  80         }
  81
  82         if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
  83             (1 << NF_INET_LOCAL_IN)) &&
  84             info->flags & IPT_ADDRTYPE_LIMIT_IFACE_OUT) {
  85                 printk(KERN_ERR "ipt_addrtype: output interface limitation "
  86                                 "not valid in PRE_ROUTING and INPUT\n");
  87                 return false;
  88         }
  89
  90         if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
  91             (1 << NF_INET_LOCAL_OUT)) &&
  92             info->flags & IPT_ADDRTYPE_LIMIT_IFACE_IN) {
  93                 printk(KERN_ERR "ipt_addrtype: input interface limitation "
  94                                 "not valid in POST_ROUTING and OUTPUT\n");
  95                 return false;
  96         }
  97
  98         return true;
  99 }
 100
 101 static struct xt_match addrtype_mt_reg[] __read_mostly = {
 102         {
 103                 .name           = "addrtype",
 104                 .family         = NFPROTO_IPV4,
 105                 .match          = addrtype_mt_v0,
 106                 .matchsize      = sizeof(struct ipt_addrtype_info),
 107                 .me             = THIS_MODULE
 108         },
 109         {
 110                 .name           = "addrtype",
 111                 .family         = NFPROTO_IPV4,
 112                 .revision       = 1,
 113                 .match          = addrtype_mt_v1,
 114                 .checkentry     = addrtype_mt_checkentry_v1,
 115                 .matchsize      = sizeof(struct ipt_addrtype_info_v1),
 116                 .me             = THIS_MODULE
 117         }
 118 };
 119
 120 static int __init addrtype_mt_init(void)
 121 {
 122         return xt_register_matches(addrtype_mt_reg,
 123                                    ARRAY_SIZE(addrtype_mt_reg));
 124 }
 125
 126 static void __exit addrtype_mt_exit(void)
 127 {
 128         xt_unregister_matches(addrtype_mt_reg, ARRAY_SIZE(addrtype_mt_reg));
 129 }
 130
 131 module_init(addrtype_mt_init);
 132 module_exit(addrtype_mt_exit);