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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("iptables addrtype match");
  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 net_device *in,
  34                const struct net_device *out, const struct xt_match *match,
  35                const void *matchinfo, int offset, unsigned int protoff,
  36                bool *hotdrop)
  37 {
  38         const struct ipt_addrtype_info *info = matchinfo;
  39         const struct iphdr *iph = ip_hdr(skb);
  40         bool ret = true;
  41
  42         if (info->source)
  43                 ret &= match_type(NULL, iph->saddr, info->source) ^
  44                        info->invert_source;
  45         if (info->dest)
  46                 ret &= match_type(NULL, iph->daddr, info->dest) ^
  47                        info->invert_dest;
  48
  49         return ret;
  50 }
  51
  52 static bool
  53 addrtype_mt_v1(const struct sk_buff *skb, const struct net_device *in,
  54                const struct net_device *out, const struct xt_match *match,
  55                const void *matchinfo, int offset, unsigned int protoff,
  56                bool *hotdrop)
  57 {
  58         const struct ipt_addrtype_info_v1 *info = matchinfo;
  59         const struct iphdr *iph = ip_hdr(skb);
  60         const struct net_device *dev = NULL;
  61         bool ret = true;
  62
  63         if (info->flags & IPT_ADDRTYPE_LIMIT_IFACE_IN)
  64                 dev = in;
  65         else if (info->flags & IPT_ADDRTYPE_LIMIT_IFACE_OUT)
  66                 dev = out;
  67
  68         if (info->source)
  69                 ret &= match_type(dev, iph->saddr, info->source) ^
  70                        (info->flags & IPT_ADDRTYPE_INVERT_SOURCE);
  71         if (ret && info->dest)
  72                 ret &= match_type(dev, iph->daddr, info->dest) ^
  73                        (info->flags & IPT_ADDRTYPE_INVERT_DEST);
  74         return ret;
  75 }
  76
  77 static bool
  78 addrtype_mt_checkentry_v1(const char *tablename, const void *ip_void,
  79                           const struct xt_match *match, void *matchinfo,
  80                           unsigned int hook_mask)
  81 {
  82         struct ipt_addrtype_info_v1 *info = matchinfo;
  83
  84         if (info->flags & IPT_ADDRTYPE_LIMIT_IFACE_IN &&
  85             info->flags & IPT_ADDRTYPE_LIMIT_IFACE_OUT) {
  86                 printk(KERN_ERR "ipt_addrtype: both incoming and outgoing "
  87                                 "interface limitation cannot be selected\n");
  88                 return false;
  89         }
  90
  91         if (hook_mask & (1 << NF_INET_PRE_ROUTING | 1 << NF_INET_LOCAL_IN) &&
  92             info->flags & IPT_ADDRTYPE_LIMIT_IFACE_OUT) {
  93                 printk(KERN_ERR "ipt_addrtype: output interface limitation "
  94                                 "not valid in PRE_ROUTING and INPUT\n");
  95                 return false;
  96         }
  97
  98         if (hook_mask & (1 << NF_INET_POST_ROUTING | 1 << NF_INET_LOCAL_OUT) &&
  99             info->flags & IPT_ADDRTYPE_LIMIT_IFACE_IN) {
 100                 printk(KERN_ERR "ipt_addrtype: input interface limitation "
 101                                 "not valid in POST_ROUTING and OUTPUT\n");
 102                 return false;
 103         }
 104
 105         return true;
 106 }
 107
 108 static struct xt_match addrtype_mt_reg[] __read_mostly = {
 109         {
 110                 .name           = "addrtype",
 111                 .family         = AF_INET,
 112                 .match          = addrtype_mt_v0,
 113                 .matchsize      = sizeof(struct ipt_addrtype_info),
 114                 .me             = THIS_MODULE
 115         },
 116         {
 117                 .name           = "addrtype",
 118                 .family         = AF_INET,
 119                 .revision       = 1,
 120                 .match          = addrtype_mt_v1,
 121                 .checkentry     = addrtype_mt_checkentry_v1,
 122                 .matchsize      = sizeof(struct ipt_addrtype_info_v1),
 123                 .me             = THIS_MODULE
 124         }
 125 };
 126
 127 static int __init addrtype_mt_init(void)
 128 {
 129         return xt_register_matches(addrtype_mt_reg,
 130                                    ARRAY_SIZE(addrtype_mt_reg));
 131 }
 132
 133 static void __exit addrtype_mt_exit(void)
 134 {
 135         xt_unregister_matches(addrtype_mt_reg, ARRAY_SIZE(addrtype_mt_reg));
 136 }
 137
 138 module_init(addrtype_mt_init);
 139 module_exit(addrtype_mt_exit);