net/netfilter/nft_nat.c

   1 /*
   2  * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
   3  * Copyright (c) 2012 Pablo Neira Ayuso <pablo@netfilter.org>
   4  * Copyright (c) 2012 Intel Corporation
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms and conditions of the GNU General Public License,
   8  * version 2, as published by the Free Software Foundation.
   9  *
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/ip.h>
  16 #include <linux/string.h>
  17 #include <linux/netlink.h>
  18 #include <linux/netfilter.h>
  19 #include <linux/netfilter_ipv4.h>
  20 #include <linux/netfilter/nfnetlink.h>
  21 #include <linux/netfilter/nf_tables.h>
  22 #include <net/netfilter/nf_conntrack.h>
  23 #include <net/netfilter/nf_nat.h>
  24 #include <net/netfilter/nf_nat_core.h>
  25 #include <net/netfilter/nf_tables.h>
  26 #include <net/netfilter/nf_nat_l3proto.h>
  27 #include <net/ip.h>
  28
  29 struct nft_nat {
  30         enum nft_registers      sreg_addr_min:8;
  31         enum nft_registers      sreg_addr_max:8;
  32         enum nft_registers      sreg_proto_min:8;
  33         enum nft_registers      sreg_proto_max:8;
  34         enum nf_nat_manip_type  type:8;
  35         u8                      family;
  36         u16                     flags;
  37 };
  38
  39 static void nft_nat_eval(const struct nft_expr *expr,
  40                          struct nft_regs *regs,
  41                          const struct nft_pktinfo *pkt)
  42 {
  43         const struct nft_nat *priv = nft_expr_priv(expr);
  44         enum ip_conntrack_info ctinfo;
  45         struct nf_conn *ct = nf_ct_get(pkt->skb, &ctinfo);
  46         struct nf_nat_range range;
  47
  48         memset(&range, 0, sizeof(range));
  49         if (priv->sreg_addr_min) {
  50                 if (priv->family == AF_INET) {
  51                         range.min_addr.ip = (__force __be32)
  52                                         regs->data[priv->sreg_addr_min];
  53                         range.max_addr.ip = (__force __be32)
  54                                         regs->data[priv->sreg_addr_max];
  55
  56                 } else {
  57                         memcpy(range.min_addr.ip6,
  58                                &regs->data[priv->sreg_addr_min],
  59                                sizeof(range.min_addr.ip6));
  60                         memcpy(range.max_addr.ip6,
  61                                &regs->data[priv->sreg_addr_max],
  62                                sizeof(range.max_addr.ip6));
  63                 }
  64                 range.flags |= NF_NAT_RANGE_MAP_IPS;
  65         }
  66
  67         if (priv->sreg_proto_min) {
  68                 range.min_proto.all =
  69                         *(__be16 *)&regs->data[priv->sreg_proto_min];
  70                 range.max_proto.all =
  71                         *(__be16 *)&regs->data[priv->sreg_proto_max];
  72                 range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
  73         }
  74
  75         range.flags |= priv->flags;
  76
  77         regs->verdict.code = nf_nat_setup_info(ct, &range, priv->type);
  78 }
  79
  80 static const struct nla_policy nft_nat_policy[NFTA_NAT_MAX + 1] = {
  81         [NFTA_NAT_TYPE]          = { .type = NLA_U32 },
  82         [NFTA_NAT_FAMILY]        = { .type = NLA_U32 },
  83         [NFTA_NAT_REG_ADDR_MIN]  = { .type = NLA_U32 },
  84         [NFTA_NAT_REG_ADDR_MAX]  = { .type = NLA_U32 },
  85         [NFTA_NAT_REG_PROTO_MIN] = { .type = NLA_U32 },
  86         [NFTA_NAT_REG_PROTO_MAX] = { .type = NLA_U32 },
  87         [NFTA_NAT_FLAGS]         = { .type = NLA_U32 },
  88 };
  89
  90 static int nft_nat_validate(const struct nft_ctx *ctx,
  91                             const struct nft_expr *expr,
  92                             const struct nft_data **data)
  93 {
  94         struct nft_nat *priv = nft_expr_priv(expr);
  95         int err;
  96
  97         err = nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
  98         if (err < 0)
  99                 return err;
 100
 101         switch (priv->type) {
 102         case NFT_NAT_SNAT:
 103                 err = nft_chain_validate_hooks(ctx->chain,
 104                                                (1 << NF_INET_POST_ROUTING) |
 105                                                (1 << NF_INET_LOCAL_IN));
 106                 break;
 107         case NFT_NAT_DNAT:
 108                 err = nft_chain_validate_hooks(ctx->chain,
 109                                                (1 << NF_INET_PRE_ROUTING) |
 110                                                (1 << NF_INET_LOCAL_OUT));
 111                 break;
 112         }
 113
 114         return err;
 115 }
 116
 117 static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 118                         const struct nlattr * const tb[])
 119 {
 120         struct nft_nat *priv = nft_expr_priv(expr);
 121         unsigned int alen, plen;
 122         u32 family;
 123         int err;
 124
 125         if (tb[NFTA_NAT_TYPE] == NULL ||
 126             (tb[NFTA_NAT_REG_ADDR_MIN] == NULL &&
 127              tb[NFTA_NAT_REG_PROTO_MIN] == NULL))
 128                 return -EINVAL;
 129
 130         switch (ntohl(nla_get_be32(tb[NFTA_NAT_TYPE]))) {
 131         case NFT_NAT_SNAT:
 132                 priv->type = NF_NAT_MANIP_SRC;
 133                 break;
 134         case NFT_NAT_DNAT:
 135                 priv->type = NF_NAT_MANIP_DST;
 136                 break;
 137         default:
 138                 return -EINVAL;
 139         }
 140
 141         err = nft_nat_validate(ctx, expr, NULL);
 142         if (err < 0)
 143                 return err;
 144
 145         if (tb[NFTA_NAT_FAMILY] == NULL)
 146                 return -EINVAL;
 147
 148         family = ntohl(nla_get_be32(tb[NFTA_NAT_FAMILY]));
 149         if (family != ctx->afi->family)
 150                 return -EOPNOTSUPP;
 151
 152         switch (family) {
 153         case NFPROTO_IPV4:
 154                 alen = FIELD_SIZEOF(struct nf_nat_range, min_addr.ip);
 155                 break;
 156         case NFPROTO_IPV6:
 157                 alen = FIELD_SIZEOF(struct nf_nat_range, min_addr.ip6);
 158                 break;
 159         default:
 160                 return -EAFNOSUPPORT;
 161         }
 162         priv->family = family;
 163
 164         if (tb[NFTA_NAT_REG_ADDR_MIN]) {
 165                 priv->sreg_addr_min =
 166                         nft_parse_register(tb[NFTA_NAT_REG_ADDR_MIN]);
 167                 err = nft_validate_register_load(priv->sreg_addr_min, alen);
 168                 if (err < 0)
 169                         return err;
 170
 171                 if (tb[NFTA_NAT_REG_ADDR_MAX]) {
 172                         priv->sreg_addr_max =
 173                                 nft_parse_register(tb[NFTA_NAT_REG_ADDR_MAX]);
 174
 175                         err = nft_validate_register_load(priv->sreg_addr_max,
 176                                                          alen);
 177                         if (err < 0)
 178                                 return err;
 179                 } else {
 180                         priv->sreg_addr_max = priv->sreg_addr_min;
 181                 }
 182         }
 183
 184         plen = FIELD_SIZEOF(struct nf_nat_range, min_addr.all);
 185         if (tb[NFTA_NAT_REG_PROTO_MIN]) {
 186                 priv->sreg_proto_min =
 187                         nft_parse_register(tb[NFTA_NAT_REG_PROTO_MIN]);
 188
 189                 err = nft_validate_register_load(priv->sreg_proto_min, plen);
 190                 if (err < 0)
 191                         return err;
 192
 193                 if (tb[NFTA_NAT_REG_PROTO_MAX]) {
 194                         priv->sreg_proto_max =
 195                                 nft_parse_register(tb[NFTA_NAT_REG_PROTO_MAX]);
 196
 197                         err = nft_validate_register_load(priv->sreg_proto_max,
 198                                                          plen);
 199                         if (err < 0)
 200                                 return err;
 201                 } else {
 202                         priv->sreg_proto_max = priv->sreg_proto_min;
 203                 }
 204         }
 205
 206         if (tb[NFTA_NAT_FLAGS]) {
 207                 priv->flags = ntohl(nla_get_be32(tb[NFTA_NAT_FLAGS]));
 208                 if (priv->flags & ~NF_NAT_RANGE_MASK)
 209                         return -EINVAL;
 210         }
 211
 212         return 0;
 213 }
 214
 215 static int nft_nat_dump(struct sk_buff *skb, const struct nft_expr *expr)
 216 {
 217         const struct nft_nat *priv = nft_expr_priv(expr);
 218
 219         switch (priv->type) {
 220         case NF_NAT_MANIP_SRC:
 221                 if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_SNAT)))
 222                         goto nla_put_failure;
 223                 break;
 224         case NF_NAT_MANIP_DST:
 225                 if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_DNAT)))
 226                         goto nla_put_failure;
 227                 break;
 228         }
 229
 230         if (nla_put_be32(skb, NFTA_NAT_FAMILY, htonl(priv->family)))
 231                 goto nla_put_failure;
 232
 233         if (priv->sreg_addr_min) {
 234                 if (nft_dump_register(skb, NFTA_NAT_REG_ADDR_MIN,
 235                                       priv->sreg_addr_min) ||
 236                     nft_dump_register(skb, NFTA_NAT_REG_ADDR_MAX,
 237                                       priv->sreg_addr_max))
 238                         goto nla_put_failure;
 239         }
 240
 241         if (priv->sreg_proto_min) {
 242                 if (nft_dump_register(skb, NFTA_NAT_REG_PROTO_MIN,
 243                                       priv->sreg_proto_min) ||
 244                     nft_dump_register(skb, NFTA_NAT_REG_PROTO_MAX,
 245                                       priv->sreg_proto_max))
 246                         goto nla_put_failure;
 247         }
 248
 249         if (priv->flags != 0) {
 250                 if (nla_put_be32(skb, NFTA_NAT_FLAGS, htonl(priv->flags)))
 251                         goto nla_put_failure;
 252         }
 253
 254         return 0;
 255
 256 nla_put_failure:
 257         return -1;
 258 }
 259
 260 static struct nft_expr_type nft_nat_type;
 261 static const struct nft_expr_ops nft_nat_ops = {
 262         .type           = &nft_nat_type,
 263         .size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
 264         .eval           = nft_nat_eval,
 265         .init           = nft_nat_init,
 266         .dump           = nft_nat_dump,
 267         .validate       = nft_nat_validate,
 268 };
 269
 270 static struct nft_expr_type nft_nat_type __read_mostly = {
 271         .name           = "nat",
 272         .ops            = &nft_nat_ops,
 273         .policy         = nft_nat_policy,
 274         .maxattr        = NFTA_NAT_MAX,
 275         .owner          = THIS_MODULE,
 276 };
 277
 278 static int __init nft_nat_module_init(void)
 279 {
 280         return nft_register_expr(&nft_nat_type);
 281 }
 282
 283 static void __exit nft_nat_module_exit(void)
 284 {
 285         nft_unregister_expr(&nft_nat_type);
 286 }
 287
 288 module_init(nft_nat_module_init);
 289 module_exit(nft_nat_module_exit);
 290
 291 MODULE_LICENSE("GPL");
 292 MODULE_AUTHOR("Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>");
 293 MODULE_ALIAS_NFT_EXPR("nat");