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         struct flowi6 flow;
  40         struct rt6_info *rt;
  41         u32 ret = 0;
  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         if (dev && (mask & XT_ADDRTYPE_LOCAL)) {
  50                 if (nf_ipv6_chk_addr(net, addr, dev, true))
  51                         ret = XT_ADDRTYPE_LOCAL;
  52         }
  53
  54         route_err = nf_ip6_route(net, (struct dst_entry **)&rt,
  55                                  flowi6_to_flowi(&flow), false);
  56         if (route_err)
  57                 return XT_ADDRTYPE_UNREACHABLE;
  58
  59         if (rt->rt6i_flags & RTF_REJECT)
  60                 ret = XT_ADDRTYPE_UNREACHABLE;
  61
  62         if (dev == NULL && rt->rt6i_flags & RTF_LOCAL)
  63                 ret |= XT_ADDRTYPE_LOCAL;
  64         if (ipv6_anycast_destination((struct dst_entry *)rt, addr))
  65                 ret |= XT_ADDRTYPE_ANYCAST;
  66
  67         dst_release(&rt->dst);
  68         return ret;
  69 }
  70
  71 static bool match_type6(struct net *net, const struct net_device *dev,
  72                                 const struct in6_addr *addr, u16 mask)
  73 {
  74         int addr_type = ipv6_addr_type(addr);
  75
  76         if ((mask & XT_ADDRTYPE_MULTICAST) &&
  77             !(addr_type & IPV6_ADDR_MULTICAST))
  78                 return false;
  79         if ((mask & XT_ADDRTYPE_UNICAST) && !(addr_type & IPV6_ADDR_UNICAST))
  80                 return false;
  81         if ((mask & XT_ADDRTYPE_UNSPEC) && addr_type != IPV6_ADDR_ANY)
  82                 return false;
  83
  84         if ((XT_ADDRTYPE_LOCAL | XT_ADDRTYPE_ANYCAST |
  85              XT_ADDRTYPE_UNREACHABLE) & mask)
  86                 return !!(mask & match_lookup_rt6(net, dev, addr, mask));
  87         return true;
  88 }
  89
  90 static bool
  91 addrtype_mt6(struct net *net, const struct net_device *dev,
  92         const struct sk_buff *skb, const struct xt_addrtype_info_v1 *info)
  93 {
  94         const struct ipv6hdr *iph = ipv6_hdr(skb);
  95         bool ret = true;
  96
  97         if (info->source)
  98                 ret &= match_type6(net, dev, &iph->saddr, info->source) ^
  99                        (info->flags & XT_ADDRTYPE_INVERT_SOURCE);
 100         if (ret && info->dest)
 101                 ret &= match_type6(net, dev, &iph->daddr, info->dest) ^
 102                        !!(info->flags & XT_ADDRTYPE_INVERT_DEST);
 103         return ret;
 104 }
 105 #endif
 106
 107 static inline bool match_type(struct net *net, const struct net_device *dev,
 108                               __be32 addr, u_int16_t mask)
 109 {
 110         return !!(mask & (1 << inet_dev_addr_type(net, dev, addr)));
 111 }
 112
 113 static bool
 114 addrtype_mt_v0(const struct sk_buff *skb, struct xt_action_param *par)
 115 {
 116         struct net *net = xt_net(par);
 117         const struct xt_addrtype_info *info = par->matchinfo;
 118         const struct iphdr *iph = ip_hdr(skb);
 119         bool ret = true;
 120
 121         if (info->source)
 122                 ret &= match_type(net, NULL, iph->saddr, info->source) ^
 123                        info->invert_source;
 124         if (info->dest)
 125                 ret &= match_type(net, NULL, iph->daddr, info->dest) ^
 126                        info->invert_dest;
 127
 128         return ret;
 129 }
 130
 131 static bool
 132 addrtype_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
 133 {
 134         struct net *net = xt_net(par);
 135         const struct xt_addrtype_info_v1 *info = par->matchinfo;
 136         const struct iphdr *iph;
 137         const struct net_device *dev = NULL;
 138         bool ret = true;
 139
 140         if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN)
 141                 dev = xt_in(par);
 142         else if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT)
 143                 dev = xt_out(par);
 144
 145 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 146         if (xt_family(par) == NFPROTO_IPV6)
 147                 return addrtype_mt6(net, dev, skb, info);
 148 #endif
 149         iph = ip_hdr(skb);
 150         if (info->source)
 151                 ret &= match_type(net, dev, iph->saddr, info->source) ^
 152                        (info->flags & XT_ADDRTYPE_INVERT_SOURCE);
 153         if (ret && info->dest)
 154                 ret &= match_type(net, dev, iph->daddr, info->dest) ^
 155                        !!(info->flags & XT_ADDRTYPE_INVERT_DEST);
 156         return ret;
 157 }
 158
 159 static int addrtype_mt_checkentry_v1(const struct xt_mtchk_param *par)
 160 {
 161         const char *errmsg = "both incoming and outgoing interface limitation cannot be selected";
 162         struct xt_addrtype_info_v1 *info = par->matchinfo;
 163
 164         if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN &&
 165             info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT)
 166                 goto err;
 167
 168         if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
 169             (1 << NF_INET_LOCAL_IN)) &&
 170             info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT) {
 171                 errmsg = "output interface limitation not valid in PREROUTING and INPUT";
 172                 goto err;
 173         }
 174
 175         if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
 176             (1 << NF_INET_LOCAL_OUT)) &&
 177             info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN) {
 178                 errmsg = "input interface limitation not valid in POSTROUTING and OUTPUT";
 179                 goto err;
 180         }
 181
 182 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 183         if (par->family == NFPROTO_IPV6) {
 184                 if ((info->source | info->dest) & XT_ADDRTYPE_BLACKHOLE) {
 185                         errmsg = "ipv6 BLACKHOLE matching not supported";
 186                         goto err;
 187                 }
 188                 if ((info->source | info->dest) >= XT_ADDRTYPE_PROHIBIT) {
 189                         errmsg = "ipv6 PROHIBIT (THROW, NAT ..) matching not supported";
 190                         goto err;
 191                 }
 192                 if ((info->source | info->dest) & XT_ADDRTYPE_BROADCAST) {
 193                         errmsg = "ipv6 does not support BROADCAST matching";
 194                         goto err;
 195                 }
 196         }
 197 #endif
 198         return 0;
 199 err:
 200         pr_info_ratelimited("%s\n", errmsg);
 201         return -EINVAL;
 202 }
 203
 204 static struct xt_match addrtype_mt_reg[] __read_mostly = {
 205         {
 206                 .name           = "addrtype",
 207                 .family         = NFPROTO_IPV4,
 208                 .match          = addrtype_mt_v0,
 209                 .matchsize      = sizeof(struct xt_addrtype_info),
 210                 .me             = THIS_MODULE
 211         },
 212         {
 213                 .name           = "addrtype",
 214                 .family         = NFPROTO_UNSPEC,
 215                 .revision       = 1,
 216                 .match          = addrtype_mt_v1,
 217                 .checkentry     = addrtype_mt_checkentry_v1,
 218                 .matchsize      = sizeof(struct xt_addrtype_info_v1),
 219                 .me             = THIS_MODULE
 220         }
 221 };
 222
 223 static int __init addrtype_mt_init(void)
 224 {
 225         return xt_register_matches(addrtype_mt_reg,
 226                                    ARRAY_SIZE(addrtype_mt_reg));
 227 }
 228
 229 static void __exit addrtype_mt_exit(void)
 230 {
 231         xt_unregister_matches(addrtype_mt_reg, ARRAY_SIZE(addrtype_mt_reg));
 232 }
 233
 234 module_init(addrtype_mt_init);
 235 module_exit(addrtype_mt_exit);