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   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
  72 addrtype_mt_checkentry_v1(const char *tablename, const void *ip_void,
  73                           const struct xt_match *match, void *matchinfo,
  74                           unsigned int hook_mask)
  75 {
  76         struct ipt_addrtype_info_v1 *info = matchinfo;
  77
  78         if (info->flags & IPT_ADDRTYPE_LIMIT_IFACE_IN &&
  79             info->flags & IPT_ADDRTYPE_LIMIT_IFACE_OUT) {
  80                 printk(KERN_ERR "ipt_addrtype: both incoming and outgoing "
  81                                 "interface limitation cannot be selected\n");
  82                 return false;
  83         }
  84
  85         if (hook_mask & (1 << NF_INET_PRE_ROUTING | 1 << NF_INET_LOCAL_IN) &&
  86             info->flags & IPT_ADDRTYPE_LIMIT_IFACE_OUT) {
  87                 printk(KERN_ERR "ipt_addrtype: output interface limitation "
  88                                 "not valid in PRE_ROUTING and INPUT\n");
  89                 return false;
  90         }
  91
  92         if (hook_mask & (1 << NF_INET_POST_ROUTING | 1 << NF_INET_LOCAL_OUT) &&
  93             info->flags & IPT_ADDRTYPE_LIMIT_IFACE_IN) {
  94                 printk(KERN_ERR "ipt_addrtype: input interface limitation "
  95                                 "not valid in POST_ROUTING and OUTPUT\n");
  96                 return false;
  97         }
  98
  99         return true;
 100 }
 101
 102 static struct xt_match addrtype_mt_reg[] __read_mostly = {
 103         {
 104                 .name           = "addrtype",
 105                 .family         = NFPROTO_IPV4,
 106                 .match          = addrtype_mt_v0,
 107                 .matchsize      = sizeof(struct ipt_addrtype_info),
 108                 .me             = THIS_MODULE
 109         },
 110         {
 111                 .name           = "addrtype",
 112                 .family         = NFPROTO_IPV4,
 113                 .revision       = 1,
 114                 .match          = addrtype_mt_v1,
 115                 .checkentry     = addrtype_mt_checkentry_v1,
 116                 .matchsize      = sizeof(struct ipt_addrtype_info_v1),
 117                 .me             = THIS_MODULE
 118         }
 119 };
 120
 121 static int __init addrtype_mt_init(void)
 122 {
 123         return xt_register_matches(addrtype_mt_reg,
 124                                    ARRAY_SIZE(addrtype_mt_reg));
 125 }
 126
 127 static void __exit addrtype_mt_exit(void)
 128 {
 129         xt_unregister_matches(addrtype_mt_reg, ARRAY_SIZE(addrtype_mt_reg));
 130 }
 131
 132 module_init(addrtype_mt_init);
 133 module_exit(addrtype_mt_exit);