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         rcu_read_lock();
  51
  52         afinfo = nf_get_afinfo(NFPROTO_IPV6);
  53         if (afinfo != NULL) {
  54                 const struct nf_ipv6_ops *v6ops;
  55
  56                 if (dev && (mask & XT_ADDRTYPE_LOCAL)) {
  57                         v6ops = nf_get_ipv6_ops();
  58                         if (v6ops && v6ops->chk_addr(net, addr, dev, true))
  59                                 ret = XT_ADDRTYPE_LOCAL;
  60                 }
  61                 route_err = afinfo->route(net, (struct dst_entry **)&rt,
  62                                           flowi6_to_flowi(&flow), false);
  63         } else {
  64                 route_err = 1;
  65         }
  66         rcu_read_unlock();
  67
  68         if (route_err)
  69                 return XT_ADDRTYPE_UNREACHABLE;
  70
  71         if (rt->rt6i_flags & RTF_REJECT)
  72                 ret = XT_ADDRTYPE_UNREACHABLE;
  73
  74         if (dev == NULL && rt->rt6i_flags & RTF_LOCAL)
  75                 ret |= XT_ADDRTYPE_LOCAL;
  76         if (rt->rt6i_flags & RTF_ANYCAST)
  77                 ret |= XT_ADDRTYPE_ANYCAST;
  78
  79         dst_release(&rt->dst);
  80         return ret;
  81 }
  82
  83 static bool match_type6(struct net *net, const struct net_device *dev,
  84                                 const struct in6_addr *addr, u16 mask)
  85 {
  86         int addr_type = ipv6_addr_type(addr);
  87
  88         if ((mask & XT_ADDRTYPE_MULTICAST) &&
  89             !(addr_type & IPV6_ADDR_MULTICAST))
  90                 return false;
  91         if ((mask & XT_ADDRTYPE_UNICAST) && !(addr_type & IPV6_ADDR_UNICAST))
  92                 return false;
  93         if ((mask & XT_ADDRTYPE_UNSPEC) && addr_type != IPV6_ADDR_ANY)
  94                 return false;
  95
  96         if ((XT_ADDRTYPE_LOCAL | XT_ADDRTYPE_ANYCAST |
  97              XT_ADDRTYPE_UNREACHABLE) & mask)
  98                 return !!(mask & match_lookup_rt6(net, dev, addr, mask));
  99         return true;
 100 }
 101
 102 static bool
 103 addrtype_mt6(struct net *net, const struct net_device *dev,
 104         const struct sk_buff *skb, const struct xt_addrtype_info_v1 *info)
 105 {
 106         const struct ipv6hdr *iph = ipv6_hdr(skb);
 107         bool ret = true;
 108
 109         if (info->source)
 110                 ret &= match_type6(net, dev, &iph->saddr, info->source) ^
 111                        (info->flags & XT_ADDRTYPE_INVERT_SOURCE);
 112         if (ret && info->dest)
 113                 ret &= match_type6(net, dev, &iph->daddr, info->dest) ^
 114                        !!(info->flags & XT_ADDRTYPE_INVERT_DEST);
 115         return ret;
 116 }
 117 #endif
 118
 119 static inline bool match_type(struct net *net, const struct net_device *dev,
 120                               __be32 addr, u_int16_t mask)
 121 {
 122         return !!(mask & (1 << inet_dev_addr_type(net, dev, addr)));
 123 }
 124
 125 static bool
 126 addrtype_mt_v0(const struct sk_buff *skb, struct xt_action_param *par)
 127 {
 128         struct net *net = dev_net(par->in ? par->in : par->out);
 129         const struct xt_addrtype_info *info = par->matchinfo;
 130         const struct iphdr *iph = ip_hdr(skb);
 131         bool ret = true;
 132
 133         if (info->source)
 134                 ret &= match_type(net, NULL, iph->saddr, info->source) ^
 135                        info->invert_source;
 136         if (info->dest)
 137                 ret &= match_type(net, NULL, iph->daddr, info->dest) ^
 138                        info->invert_dest;
 139
 140         return ret;
 141 }
 142
 143 static bool
 144 addrtype_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
 145 {
 146         struct net *net = dev_net(par->in ? par->in : par->out);
 147         const struct xt_addrtype_info_v1 *info = par->matchinfo;
 148         const struct iphdr *iph;
 149         const struct net_device *dev = NULL;
 150         bool ret = true;
 151
 152         if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN)
 153                 dev = par->in;
 154         else if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT)
 155                 dev = par->out;
 156
 157 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 158         if (par->family == NFPROTO_IPV6)
 159                 return addrtype_mt6(net, dev, skb, info);
 160 #endif
 161         iph = ip_hdr(skb);
 162         if (info->source)
 163                 ret &= match_type(net, dev, iph->saddr, info->source) ^
 164                        (info->flags & XT_ADDRTYPE_INVERT_SOURCE);
 165         if (ret && info->dest)
 166                 ret &= match_type(net, dev, iph->daddr, info->dest) ^
 167                        !!(info->flags & XT_ADDRTYPE_INVERT_DEST);
 168         return ret;
 169 }
 170
 171 static int addrtype_mt_checkentry_v1(const struct xt_mtchk_param *par)
 172 {
 173         struct xt_addrtype_info_v1 *info = par->matchinfo;
 174
 175         if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN &&
 176             info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT) {
 177                 pr_info("both incoming and outgoing "
 178                         "interface limitation cannot be selected\n");
 179                 return -EINVAL;
 180         }
 181
 182         if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
 183             (1 << NF_INET_LOCAL_IN)) &&
 184             info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT) {
 185                 pr_info("output interface limitation "
 186                         "not valid in PREROUTING and INPUT\n");
 187                 return -EINVAL;
 188         }
 189
 190         if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
 191             (1 << NF_INET_LOCAL_OUT)) &&
 192             info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN) {
 193                 pr_info("input interface limitation "
 194                         "not valid in POSTROUTING and OUTPUT\n");
 195                 return -EINVAL;
 196         }
 197
 198 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 199         if (par->family == NFPROTO_IPV6) {
 200                 if ((info->source | info->dest) & XT_ADDRTYPE_BLACKHOLE) {
 201                         pr_err("ipv6 BLACKHOLE matching not supported\n");
 202                         return -EINVAL;
 203                 }
 204                 if ((info->source | info->dest) >= XT_ADDRTYPE_PROHIBIT) {
 205                         pr_err("ipv6 PROHIBT (THROW, NAT ..) matching not supported\n");
 206                         return -EINVAL;
 207                 }
 208                 if ((info->source | info->dest) & XT_ADDRTYPE_BROADCAST) {
 209                         pr_err("ipv6 does not support BROADCAST matching\n");
 210                         return -EINVAL;
 211                 }
 212         }
 213 #endif
 214         return 0;
 215 }
 216
 217 static struct xt_match addrtype_mt_reg[] __read_mostly = {
 218         {
 219                 .name           = "addrtype",
 220                 .family         = NFPROTO_IPV4,
 221                 .match          = addrtype_mt_v0,
 222                 .matchsize      = sizeof(struct xt_addrtype_info),
 223                 .me             = THIS_MODULE
 224         },
 225         {
 226                 .name           = "addrtype",
 227                 .family         = NFPROTO_UNSPEC,
 228                 .revision       = 1,
 229                 .match          = addrtype_mt_v1,
 230                 .checkentry     = addrtype_mt_checkentry_v1,
 231                 .matchsize      = sizeof(struct xt_addrtype_info_v1),
 232                 .me             = THIS_MODULE
 233         }
 234 };
 235
 236 static int __init addrtype_mt_init(void)
 237 {
 238         return xt_register_matches(addrtype_mt_reg,
 239                                    ARRAY_SIZE(addrtype_mt_reg));
 240 }
 241
 242 static void __exit addrtype_mt_exit(void)
 243 {
 244         xt_unregister_matches(addrtype_mt_reg, ARRAY_SIZE(addrtype_mt_reg));
 245 }
 246
 247 module_init(addrtype_mt_init);
 248 module_exit(addrtype_mt_exit);