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_ipv6.h>
  26 #include <linux/netfilter/xt_addrtype.h>
  27 #include <linux/netfilter/x_tables.h>
  28
  29 MODULE_LICENSE("GPL");
  30 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  31 MODULE_DESCRIPTION("Xtables: address type match");
  32 MODULE_ALIAS("ipt_addrtype");
  33 MODULE_ALIAS("ip6t_addrtype");
  34
  35 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
  36 static u32 match_lookup_rt6(struct net *net, const struct net_device *dev,
  37                             const struct in6_addr *addr, u16 mask)
  38 {
  39         const struct nf_afinfo *afinfo;
  40         struct flowi6 flow;
  41         struct rt6_info *rt;
  42         u32 ret = 0;
  43         int route_err;
  44
  45         memset(&flow, 0, sizeof(flow));
  46         flow.daddr = *addr;
  47         if (dev)
  48                 flow.flowi6_oif = dev->ifindex;
  49
  50         afinfo = nf_get_afinfo(NFPROTO_IPV6);
  51         if (afinfo != NULL) {
  52                 const struct nf_ipv6_ops *v6ops;
  53
  54                 if (dev && (mask & XT_ADDRTYPE_LOCAL)) {
  55                         v6ops = nf_get_ipv6_ops();
  56                         if (v6ops && v6ops->chk_addr(net, addr, dev, true))
  57                                 ret = XT_ADDRTYPE_LOCAL;
  58                 }
  59                 route_err = afinfo->route(net, (struct dst_entry **)&rt,
  60                                           flowi6_to_flowi(&flow), false);
  61         } else {
  62                 route_err = 1;
  63         }
  64
  65         if (route_err)
  66                 return XT_ADDRTYPE_UNREACHABLE;
  67
  68         if (rt->rt6i_flags & RTF_REJECT)
  69                 ret = XT_ADDRTYPE_UNREACHABLE;
  70
  71         if (dev == NULL && rt->rt6i_flags & RTF_LOCAL)
  72                 ret |= XT_ADDRTYPE_LOCAL;
  73         if (ipv6_anycast_destination((struct dst_entry *)rt, addr))
  74                 ret |= XT_ADDRTYPE_ANYCAST;
  75
  76         dst_release(&rt->dst);
  77         return ret;
  78 }
  79
  80 static bool match_type6(struct net *net, const struct net_device *dev,
  81                                 const struct in6_addr *addr, u16 mask)
  82 {
  83         int addr_type = ipv6_addr_type(addr);
  84
  85         if ((mask & XT_ADDRTYPE_MULTICAST) &&
  86             !(addr_type & IPV6_ADDR_MULTICAST))
  87                 return false;
  88         if ((mask & XT_ADDRTYPE_UNICAST) && !(addr_type & IPV6_ADDR_UNICAST))
  89                 return false;
  90         if ((mask & XT_ADDRTYPE_UNSPEC) && addr_type != IPV6_ADDR_ANY)
  91                 return false;
  92
  93         if ((XT_ADDRTYPE_LOCAL | XT_ADDRTYPE_ANYCAST |
  94              XT_ADDRTYPE_UNREACHABLE) & mask)
  95                 return !!(mask & match_lookup_rt6(net, dev, addr, mask));
  96         return true;
  97 }
  98
  99 static bool
 100 addrtype_mt6(struct net *net, const struct net_device *dev,
 101         const struct sk_buff *skb, const struct xt_addrtype_info_v1 *info)
 102 {
 103         const struct ipv6hdr *iph = ipv6_hdr(skb);
 104         bool ret = true;
 105
 106         if (info->source)
 107                 ret &= match_type6(net, dev, &iph->saddr, info->source) ^
 108                        (info->flags & XT_ADDRTYPE_INVERT_SOURCE);
 109         if (ret && info->dest)
 110                 ret &= match_type6(net, dev, &iph->daddr, info->dest) ^
 111                        !!(info->flags & XT_ADDRTYPE_INVERT_DEST);
 112         return ret;
 113 }
 114 #endif
 115
 116 static inline bool match_type(struct net *net, const struct net_device *dev,
 117                               __be32 addr, u_int16_t mask)
 118 {
 119         return !!(mask & (1 << inet_dev_addr_type(net, dev, addr)));
 120 }
 121
 122 static bool
 123 addrtype_mt_v0(const struct sk_buff *skb, struct xt_action_param *par)
 124 {
 125         struct net *net = xt_net(par);
 126         const struct xt_addrtype_info *info = par->matchinfo;
 127         const struct iphdr *iph = ip_hdr(skb);
 128         bool ret = true;
 129
 130         if (info->source)
 131                 ret &= match_type(net, NULL, iph->saddr, info->source) ^
 132                        info->invert_source;
 133         if (info->dest)
 134                 ret &= match_type(net, NULL, iph->daddr, info->dest) ^
 135                        info->invert_dest;
 136
 137         return ret;
 138 }
 139
 140 static bool
 141 addrtype_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
 142 {
 143         struct net *net = xt_net(par);
 144         const struct xt_addrtype_info_v1 *info = par->matchinfo;
 145         const struct iphdr *iph;
 146         const struct net_device *dev = NULL;
 147         bool ret = true;
 148
 149         if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN)
 150                 dev = xt_in(par);
 151         else if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT)
 152                 dev = xt_out(par);
 153
 154 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 155         if (xt_family(par) == NFPROTO_IPV6)
 156                 return addrtype_mt6(net, dev, skb, info);
 157 #endif
 158         iph = ip_hdr(skb);
 159         if (info->source)
 160                 ret &= match_type(net, dev, iph->saddr, info->source) ^
 161                        (info->flags & XT_ADDRTYPE_INVERT_SOURCE);
 162         if (ret && info->dest)
 163                 ret &= match_type(net, dev, iph->daddr, info->dest) ^
 164                        !!(info->flags & XT_ADDRTYPE_INVERT_DEST);
 165         return ret;
 166 }
 167
 168 static int addrtype_mt_checkentry_v1(const struct xt_mtchk_param *par)
 169 {
 170         struct xt_addrtype_info_v1 *info = par->matchinfo;
 171
 172         if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN &&
 173             info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT) {
 174                 pr_info("both incoming and outgoing "
 175                         "interface limitation cannot be selected\n");
 176                 return -EINVAL;
 177         }
 178
 179         if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
 180             (1 << NF_INET_LOCAL_IN)) &&
 181             info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT) {
 182                 pr_info("output interface limitation "
 183                         "not valid in PREROUTING and INPUT\n");
 184                 return -EINVAL;
 185         }
 186
 187         if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
 188             (1 << NF_INET_LOCAL_OUT)) &&
 189             info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN) {
 190                 pr_info("input interface limitation "
 191                         "not valid in POSTROUTING and OUTPUT\n");
 192                 return -EINVAL;
 193         }
 194
 195 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 196         if (par->family == NFPROTO_IPV6) {
 197                 if ((info->source | info->dest) & XT_ADDRTYPE_BLACKHOLE) {
 198                         pr_err("ipv6 BLACKHOLE matching not supported\n");
 199                         return -EINVAL;
 200                 }
 201                 if ((info->source | info->dest) >= XT_ADDRTYPE_PROHIBIT) {
 202                         pr_err("ipv6 PROHIBIT (THROW, NAT ..) matching not supported\n");
 203                         return -EINVAL;
 204                 }
 205                 if ((info->source | info->dest) & XT_ADDRTYPE_BROADCAST) {
 206                         pr_err("ipv6 does not support BROADCAST matching\n");
 207                         return -EINVAL;
 208                 }
 209         }
 210 #endif
 211         return 0;
 212 }
 213
 214 static struct xt_match addrtype_mt_reg[] __read_mostly = {
 215         {
 216                 .name           = "addrtype",
 217                 .family         = NFPROTO_IPV4,
 218                 .match          = addrtype_mt_v0,
 219                 .matchsize      = sizeof(struct xt_addrtype_info),
 220                 .me             = THIS_MODULE
 221         },
 222         {
 223                 .name           = "addrtype",
 224                 .family         = NFPROTO_UNSPEC,
 225                 .revision       = 1,
 226                 .match          = addrtype_mt_v1,
 227                 .checkentry     = addrtype_mt_checkentry_v1,
 228                 .matchsize      = sizeof(struct xt_addrtype_info_v1),
 229                 .me             = THIS_MODULE
 230         }
 231 };
 232
 233 static int __init addrtype_mt_init(void)
 234 {
 235         return xt_register_matches(addrtype_mt_reg,
 236                                    ARRAY_SIZE(addrtype_mt_reg));
 237 }
 238
 239 static void __exit addrtype_mt_exit(void)
 240 {
 241         xt_unregister_matches(addrtype_mt_reg, ARRAY_SIZE(addrtype_mt_reg));
 242 }
 243
 244 module_init(addrtype_mt_init);
 245 module_exit(addrtype_mt_exit);