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_ipv6_ops *v6ops;
  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         v6ops = nf_get_ipv6_ops();
  51         if (v6ops) {
  52                 if (dev && (mask & XT_ADDRTYPE_LOCAL)) {
  53                         if (v6ops->chk_addr(net, addr, dev, true))
  54                                 ret = XT_ADDRTYPE_LOCAL;
  55                 }
  56                 route_err = v6ops->route(net, (struct dst_entry **)&rt,
  57                                          flowi6_to_flowi(&flow), false);
  58         } else {
  59                 route_err = 1;
  60         }
  61
  62         if (route_err)
  63                 return XT_ADDRTYPE_UNREACHABLE;
  64
  65         if (rt->rt6i_flags & RTF_REJECT)
  66                 ret = XT_ADDRTYPE_UNREACHABLE;
  67
  68         if (dev == NULL && rt->rt6i_flags & RTF_LOCAL)
  69                 ret |= XT_ADDRTYPE_LOCAL;
  70         if (ipv6_anycast_destination((struct dst_entry *)rt, addr))
  71                 ret |= XT_ADDRTYPE_ANYCAST;
  72
  73         dst_release(&rt->dst);
  74         return ret;
  75 }
  76
  77 static bool match_type6(struct net *net, const struct net_device *dev,
  78                                 const struct in6_addr *addr, u16 mask)
  79 {
  80         int addr_type = ipv6_addr_type(addr);
  81
  82         if ((mask & XT_ADDRTYPE_MULTICAST) &&
  83             !(addr_type & IPV6_ADDR_MULTICAST))
  84                 return false;
  85         if ((mask & XT_ADDRTYPE_UNICAST) && !(addr_type & IPV6_ADDR_UNICAST))
  86                 return false;
  87         if ((mask & XT_ADDRTYPE_UNSPEC) && addr_type != IPV6_ADDR_ANY)
  88                 return false;
  89
  90         if ((XT_ADDRTYPE_LOCAL | XT_ADDRTYPE_ANYCAST |
  91              XT_ADDRTYPE_UNREACHABLE) & mask)
  92                 return !!(mask & match_lookup_rt6(net, dev, addr, mask));
  93         return true;
  94 }
  95
  96 static bool
  97 addrtype_mt6(struct net *net, const struct net_device *dev,
  98         const struct sk_buff *skb, const struct xt_addrtype_info_v1 *info)
  99 {
 100         const struct ipv6hdr *iph = ipv6_hdr(skb);
 101         bool ret = true;
 102
 103         if (info->source)
 104                 ret &= match_type6(net, dev, &iph->saddr, info->source) ^
 105                        (info->flags & XT_ADDRTYPE_INVERT_SOURCE);
 106         if (ret && info->dest)
 107                 ret &= match_type6(net, dev, &iph->daddr, info->dest) ^
 108                        !!(info->flags & XT_ADDRTYPE_INVERT_DEST);
 109         return ret;
 110 }
 111 #endif
 112
 113 static inline bool match_type(struct net *net, const struct net_device *dev,
 114                               __be32 addr, u_int16_t mask)
 115 {
 116         return !!(mask & (1 << inet_dev_addr_type(net, dev, addr)));
 117 }
 118
 119 static bool
 120 addrtype_mt_v0(const struct sk_buff *skb, struct xt_action_param *par)
 121 {
 122         struct net *net = xt_net(par);
 123         const struct xt_addrtype_info *info = par->matchinfo;
 124         const struct iphdr *iph = ip_hdr(skb);
 125         bool ret = true;
 126
 127         if (info->source)
 128                 ret &= match_type(net, NULL, iph->saddr, info->source) ^
 129                        info->invert_source;
 130         if (info->dest)
 131                 ret &= match_type(net, NULL, iph->daddr, info->dest) ^
 132                        info->invert_dest;
 133
 134         return ret;
 135 }
 136
 137 static bool
 138 addrtype_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
 139 {
 140         struct net *net = xt_net(par);
 141         const struct xt_addrtype_info_v1 *info = par->matchinfo;
 142         const struct iphdr *iph;
 143         const struct net_device *dev = NULL;
 144         bool ret = true;
 145
 146         if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN)
 147                 dev = xt_in(par);
 148         else if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT)
 149                 dev = xt_out(par);
 150
 151 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 152         if (xt_family(par) == NFPROTO_IPV6)
 153                 return addrtype_mt6(net, dev, skb, info);
 154 #endif
 155         iph = ip_hdr(skb);
 156         if (info->source)
 157                 ret &= match_type(net, dev, iph->saddr, info->source) ^
 158                        (info->flags & XT_ADDRTYPE_INVERT_SOURCE);
 159         if (ret && info->dest)
 160                 ret &= match_type(net, dev, iph->daddr, info->dest) ^
 161                        !!(info->flags & XT_ADDRTYPE_INVERT_DEST);
 162         return ret;
 163 }
 164
 165 static int addrtype_mt_checkentry_v1(const struct xt_mtchk_param *par)
 166 {
 167         const char *errmsg = "both incoming and outgoing interface limitation cannot be selected";
 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                 goto err;
 173
 174         if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
 175             (1 << NF_INET_LOCAL_IN)) &&
 176             info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT) {
 177                 errmsg = "output interface limitation not valid in PREROUTING and INPUT";
 178                 goto err;
 179         }
 180
 181         if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
 182             (1 << NF_INET_LOCAL_OUT)) &&
 183             info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN) {
 184                 errmsg = "input interface limitation not valid in POSTROUTING and OUTPUT";
 185                 goto err;
 186         }
 187
 188 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 189         if (par->family == NFPROTO_IPV6) {
 190                 if ((info->source | info->dest) & XT_ADDRTYPE_BLACKHOLE) {
 191                         errmsg = "ipv6 BLACKHOLE matching not supported";
 192                         goto err;
 193                 }
 194                 if ((info->source | info->dest) >= XT_ADDRTYPE_PROHIBIT) {
 195                         errmsg = "ipv6 PROHIBIT (THROW, NAT ..) matching not supported";
 196                         goto err;
 197                 }
 198                 if ((info->source | info->dest) & XT_ADDRTYPE_BROADCAST) {
 199                         errmsg = "ipv6 does not support BROADCAST matching";
 200                         goto err;
 201                 }
 202         }
 203 #endif
 204         return 0;
 205 err:
 206         pr_info_ratelimited("%s\n", errmsg);
 207         return -EINVAL;
 208 }
 209
 210 static struct xt_match addrtype_mt_reg[] __read_mostly = {
 211         {
 212                 .name           = "addrtype",
 213                 .family         = NFPROTO_IPV4,
 214                 .match          = addrtype_mt_v0,
 215                 .matchsize      = sizeof(struct xt_addrtype_info),
 216                 .me             = THIS_MODULE
 217         },
 218         {
 219                 .name           = "addrtype",
 220                 .family         = NFPROTO_UNSPEC,
 221                 .revision       = 1,
 222                 .match          = addrtype_mt_v1,
 223                 .checkentry     = addrtype_mt_checkentry_v1,
 224                 .matchsize      = sizeof(struct xt_addrtype_info_v1),
 225                 .me             = THIS_MODULE
 226         }
 227 };
 228
 229 static int __init addrtype_mt_init(void)
 230 {
 231         return xt_register_matches(addrtype_mt_reg,
 232                                    ARRAY_SIZE(addrtype_mt_reg));
 233 }
 234
 235 static void __exit addrtype_mt_exit(void)
 236 {
 237         xt_unregister_matches(addrtype_mt_reg, ARRAY_SIZE(addrtype_mt_reg));
 238 }
 239
 240 module_init(addrtype_mt_init);
 241 module_exit(addrtype_mt_exit);