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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(struct net *net, const struct net_device *dev,
  27                               __be32 addr, u_int16_t mask)
  28 {
  29         return !!(mask & (1 << inet_dev_addr_type(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         struct net *net = dev_net(par->in ? par->in : par->out);
  36         const struct ipt_addrtype_info *info = par->matchinfo;
  37         const struct iphdr *iph = ip_hdr(skb);
  38         bool ret = true;
  39
  40         if (info->source)
  41                 ret &= match_type(net, NULL, iph->saddr, info->source) ^
  42                        info->invert_source;
  43         if (info->dest)
  44                 ret &= match_type(net, NULL, iph->daddr, info->dest) ^
  45                        info->invert_dest;
  46
  47         return ret;
  48 }
  49
  50 static bool
  51 addrtype_mt_v1(const struct sk_buff *skb, const struct xt_match_param *par)
  52 {
  53         struct net *net = dev_net(par->in ? par->in : par->out);
  54         const struct ipt_addrtype_info_v1 *info = par->matchinfo;
  55         const struct iphdr *iph = ip_hdr(skb);
  56         const struct net_device *dev = NULL;
  57         bool ret = true;
  58
  59         if (info->flags & IPT_ADDRTYPE_LIMIT_IFACE_IN)
  60                 dev = par->in;
  61         else if (info->flags & IPT_ADDRTYPE_LIMIT_IFACE_OUT)
  62                 dev = par->out;
  63
  64         if (info->source)
  65                 ret &= match_type(net, dev, iph->saddr, info->source) ^
  66                        (info->flags & IPT_ADDRTYPE_INVERT_SOURCE);
  67         if (ret && info->dest)
  68                 ret &= match_type(net, dev, iph->daddr, info->dest) ^
  69                        !!(info->flags & IPT_ADDRTYPE_INVERT_DEST);
  70         return ret;
  71 }
  72
  73 static bool addrtype_mt_checkentry_v1(const struct xt_mtchk_param *par)
  74 {
  75         struct ipt_addrtype_info_v1 *info = par->matchinfo;
  76
  77         if (info->flags & IPT_ADDRTYPE_LIMIT_IFACE_IN &&
  78             info->flags & IPT_ADDRTYPE_LIMIT_IFACE_OUT) {
  79                 printk(KERN_ERR "ipt_addrtype: both incoming and outgoing "
  80                                 "interface limitation cannot be selected\n");
  81                 return false;
  82         }
  83
  84         if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
  85             (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 (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
  93             (1 << NF_INET_LOCAL_OUT)) &&
  94             info->flags & IPT_ADDRTYPE_LIMIT_IFACE_IN) {
  95                 printk(KERN_ERR "ipt_addrtype: input interface limitation "
  96                                 "not valid in POST_ROUTING and OUTPUT\n");
  97                 return false;
  98         }
  99
 100         return true;
 101 }
 102
 103 static struct xt_match addrtype_mt_reg[] __read_mostly = {
 104         {
 105                 .name           = "addrtype",
 106                 .family         = NFPROTO_IPV4,
 107                 .match          = addrtype_mt_v0,
 108                 .matchsize      = sizeof(struct ipt_addrtype_info),
 109                 .me             = THIS_MODULE
 110         },
 111         {
 112                 .name           = "addrtype",
 113                 .family         = NFPROTO_IPV4,
 114                 .revision       = 1,
 115                 .match          = addrtype_mt_v1,
 116                 .checkentry     = addrtype_mt_checkentry_v1,
 117                 .matchsize      = sizeof(struct ipt_addrtype_info_v1),
 118                 .me             = THIS_MODULE
 119         }
 120 };
 121
 122 static int __init addrtype_mt_init(void)
 123 {
 124         return xt_register_matches(addrtype_mt_reg,
 125                                    ARRAY_SIZE(addrtype_mt_reg));
 126 }
 127
 128 static void __exit addrtype_mt_exit(void)
 129 {
 130         xt_unregister_matches(addrtype_mt_reg, ARRAY_SIZE(addrtype_mt_reg));
 131 }
 132
 133 module_init(addrtype_mt_init);
 134 module_exit(addrtype_mt_exit);