net/netfilter/xt_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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  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 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
  20 #include <net/ipv6.h>
  21 #include <net/ip6_route.h>
  22 #include <net/ip6_fib.h>
  23 #endif
  24
  25 #include <linux/netfilter/xt_addrtype.h>
  26 #include <linux/netfilter/x_tables.h>
  27
  28 MODULE_LICENSE("GPL");
  29 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  30 MODULE_DESCRIPTION("Xtables: address type match");
  31 MODULE_ALIAS("ipt_addrtype");
  32 MODULE_ALIAS("ip6t_addrtype");
  33
  34 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
  35 static u32 match_lookup_rt6(struct net *net, const struct net_device *dev,
  36                             const struct in6_addr *addr)
  37 {
  38         const struct nf_afinfo *afinfo;
  39         struct flowi6 flow;
  40         struct rt6_info *rt;
  41         u32 ret;
  42         int route_err;
  43
  44         memset(&flow, 0, sizeof(flow));
  45         flow.daddr = *addr;
  46         if (dev)
  47                 flow.flowi6_oif = dev->ifindex;
  48
  49         rcu_read_lock();
  50
  51         afinfo = nf_get_afinfo(NFPROTO_IPV6);
  52         if (afinfo != NULL)
  53                 route_err = afinfo->route(net, (struct dst_entry **)&rt,
  54                                         flowi6_to_flowi(&flow), !!dev);
  55         else
  56                 route_err = 1;
  57
  58         rcu_read_unlock();
  59
  60         if (route_err)
  61                 return XT_ADDRTYPE_UNREACHABLE;
  62
  63         if (rt->rt6i_flags & RTF_REJECT)
  64                 ret = XT_ADDRTYPE_UNREACHABLE;
  65         else
  66                 ret = 0;
  67
  68         if (rt->rt6i_flags & RTF_LOCAL)
  69                 ret |= XT_ADDRTYPE_LOCAL;
  70         if (rt->rt6i_flags & RTF_ANYCAST)
  71                 ret |= XT_ADDRTYPE_ANYCAST;
  72
  73
  74         dst_release(&rt->dst);
  75         return ret;
  76 }
  77
  78 static bool match_type6(struct net *net, const struct net_device *dev,
  79                                 const struct in6_addr *addr, u16 mask)
  80 {
  81         int addr_type = ipv6_addr_type(addr);
  82
  83         if ((mask & XT_ADDRTYPE_MULTICAST) &&
  84             !(addr_type & IPV6_ADDR_MULTICAST))
  85                 return false;
  86         if ((mask & XT_ADDRTYPE_UNICAST) && !(addr_type & IPV6_ADDR_UNICAST))
  87                 return false;
  88         if ((mask & XT_ADDRTYPE_UNSPEC) && addr_type != IPV6_ADDR_ANY)
  89                 return false;
  90
  91         if ((XT_ADDRTYPE_LOCAL | XT_ADDRTYPE_ANYCAST |
  92              XT_ADDRTYPE_UNREACHABLE) & mask)
  93                 return !!(mask & match_lookup_rt6(net, dev, addr));
  94         return true;
  95 }
  96
  97 static bool
  98 addrtype_mt6(struct net *net, const struct net_device *dev,
  99         const struct sk_buff *skb, const struct xt_addrtype_info_v1 *info)
 100 {
 101         const struct ipv6hdr *iph = ipv6_hdr(skb);
 102         bool ret = true;
 103
 104         if (info->source)
 105                 ret &= match_type6(net, dev, &iph->saddr, info->source) ^
 106                        (info->flags & XT_ADDRTYPE_INVERT_SOURCE);
 107         if (ret && info->dest)
 108                 ret &= match_type6(net, dev, &iph->daddr, info->dest) ^
 109                        !!(info->flags & XT_ADDRTYPE_INVERT_DEST);
 110         return ret;
 111 }
 112 #endif
 113
 114 static inline bool match_type(struct net *net, const struct net_device *dev,
 115                               __be32 addr, u_int16_t mask)
 116 {
 117         return !!(mask & (1 << inet_dev_addr_type(net, dev, addr)));
 118 }
 119
 120 static bool
 121 addrtype_mt_v0(const struct sk_buff *skb, struct xt_action_param *par)
 122 {
 123         struct net *net = dev_net(par->in ? par->in : par->out);
 124         const struct xt_addrtype_info *info = par->matchinfo;
 125         const struct iphdr *iph = ip_hdr(skb);
 126         bool ret = true;
 127
 128         if (info->source)
 129                 ret &= match_type(net, NULL, iph->saddr, info->source) ^
 130                        info->invert_source;
 131         if (info->dest)
 132                 ret &= match_type(net, NULL, iph->daddr, info->dest) ^
 133                        info->invert_dest;
 134
 135         return ret;
 136 }
 137
 138 static bool
 139 addrtype_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
 140 {
 141         struct net *net = dev_net(par->in ? par->in : par->out);
 142         const struct xt_addrtype_info_v1 *info = par->matchinfo;
 143         const struct iphdr *iph;
 144         const struct net_device *dev = NULL;
 145         bool ret = true;
 146
 147         if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN)
 148                 dev = par->in;
 149         else if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT)
 150                 dev = par->out;
 151
 152 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 153         if (par->family == NFPROTO_IPV6)
 154                 return addrtype_mt6(net, dev, skb, info);
 155 #endif
 156         iph = ip_hdr(skb);
 157         if (info->source)
 158                 ret &= match_type(net, dev, iph->saddr, info->source) ^
 159                        (info->flags & XT_ADDRTYPE_INVERT_SOURCE);
 160         if (ret && info->dest)
 161                 ret &= match_type(net, dev, iph->daddr, info->dest) ^
 162                        !!(info->flags & XT_ADDRTYPE_INVERT_DEST);
 163         return ret;
 164 }
 165
 166 static int addrtype_mt_checkentry_v1(const struct xt_mtchk_param *par)
 167 {
 168         struct xt_addrtype_info_v1 *info = par->matchinfo;
 169
 170         if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN &&
 171             info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT) {
 172                 pr_info("both incoming and outgoing "
 173                         "interface limitation cannot be selected\n");
 174                 return -EINVAL;
 175         }
 176
 177         if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
 178             (1 << NF_INET_LOCAL_IN)) &&
 179             info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT) {
 180                 pr_info("output interface limitation "
 181                         "not valid in PREROUTING and INPUT\n");
 182                 return -EINVAL;
 183         }
 184
 185         if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
 186             (1 << NF_INET_LOCAL_OUT)) &&
 187             info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN) {
 188                 pr_info("input interface limitation "
 189                         "not valid in POSTROUTING and OUTPUT\n");
 190                 return -EINVAL;
 191         }
 192
 193 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 194         if (par->family == NFPROTO_IPV6) {
 195                 if ((info->source | info->dest) & XT_ADDRTYPE_BLACKHOLE) {
 196                         pr_err("ipv6 BLACKHOLE matching not supported\n");
 197                         return -EINVAL;
 198                 }
 199                 if ((info->source | info->dest) >= XT_ADDRTYPE_PROHIBIT) {
 200                         pr_err("ipv6 PROHIBT (THROW, NAT ..) matching not supported\n");
 201                         return -EINVAL;
 202                 }
 203                 if ((info->source | info->dest) & XT_ADDRTYPE_BROADCAST) {
 204                         pr_err("ipv6 does not support BROADCAST matching\n");
 205                         return -EINVAL;
 206                 }
 207         }
 208 #endif
 209         return 0;
 210 }
 211
 212 static struct xt_match addrtype_mt_reg[] __read_mostly = {
 213         {
 214                 .name           = "addrtype",
 215                 .family         = NFPROTO_IPV4,
 216                 .match          = addrtype_mt_v0,
 217                 .matchsize      = sizeof(struct xt_addrtype_info),
 218                 .me             = THIS_MODULE
 219         },
 220         {
 221                 .name           = "addrtype",
 222                 .family         = NFPROTO_UNSPEC,
 223                 .revision       = 1,
 224                 .match          = addrtype_mt_v1,
 225                 .checkentry     = addrtype_mt_checkentry_v1,
 226                 .matchsize      = sizeof(struct xt_addrtype_info_v1),
 227                 .me             = THIS_MODULE
 228         }
 229 };
 230
 231 static int __init addrtype_mt_init(void)
 232 {
 233         return xt_register_matches(addrtype_mt_reg,
 234                                    ARRAY_SIZE(addrtype_mt_reg));
 235 }
 236
 237 static void __exit addrtype_mt_exit(void)
 238 {
 239         xt_unregister_matches(addrtype_mt_reg, ARRAY_SIZE(addrtype_mt_reg));
 240 }
 241
 242 module_init(addrtype_mt_init);
 243 module_exit(addrtype_mt_exit);