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_data data[NFT_REG_MAX + 1],
  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                                         data[priv->sreg_addr_min].data[0];
  53                         range.max_addr.ip = (__force __be32)
  54                                         data[priv->sreg_addr_max].data[0];
  55
  56                 } else {
  57                         memcpy(range.min_addr.ip6,
  58                                data[priv->sreg_addr_min].data,
  59                                sizeof(struct nft_data));
  60                         memcpy(range.max_addr.ip6,
  61                                data[priv->sreg_addr_max].data,
  62                                sizeof(struct nft_data));
  63                 }
  64                 range.flags |= NF_NAT_RANGE_MAP_IPS;
  65         }
  66
  67         if (priv->sreg_proto_min) {
  68                 range.min_proto.all =
  69                         *(__be16 *)&data[priv->sreg_proto_min].data[0];
  70                 range.max_proto.all =
  71                         *(__be16 *)&data[priv->sreg_proto_max].data[0];
  72                 range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
  73         }
  74
  75         range.flags |= priv->flags;
  76
  77         data[NFT_REG_VERDICT].verdict =
  78                 nf_nat_setup_info(ct, &range, priv->type);
  79 }
  80
  81 static const struct nla_policy nft_nat_policy[NFTA_NAT_MAX + 1] = {
  82         [NFTA_NAT_TYPE]          = { .type = NLA_U32 },
  83         [NFTA_NAT_FAMILY]        = { .type = NLA_U32 },
  84         [NFTA_NAT_REG_ADDR_MIN]  = { .type = NLA_U32 },
  85         [NFTA_NAT_REG_ADDR_MAX]  = { .type = NLA_U32 },
  86         [NFTA_NAT_REG_PROTO_MIN] = { .type = NLA_U32 },
  87         [NFTA_NAT_REG_PROTO_MAX] = { .type = NLA_U32 },
  88         [NFTA_NAT_FLAGS]         = { .type = NLA_U32 },
  89 };
  90
  91 static int nft_nat_validate(const struct nft_ctx *ctx,
  92                             const struct nft_expr *expr,
  93                             const struct nft_data **data)
  94 {
  95         struct nft_nat *priv = nft_expr_priv(expr);
  96         int err;
  97
  98         err = nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
  99         if (err < 0)
 100                 return err;
 101
 102         switch (priv->type) {
 103         case NFT_NAT_SNAT:
 104                 err = nft_chain_validate_hooks(ctx->chain,
 105                                                (1 << NF_INET_POST_ROUTING) |
 106                                                (1 << NF_INET_LOCAL_IN));
 107                 break;
 108         case NFT_NAT_DNAT:
 109                 err = nft_chain_validate_hooks(ctx->chain,
 110                                                (1 << NF_INET_PRE_ROUTING) |
 111                                                (1 << NF_INET_LOCAL_OUT));
 112                 break;
 113         }
 114
 115         return err;
 116 }
 117
 118 static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 119                         const struct nlattr * const tb[])
 120 {
 121         struct nft_nat *priv = nft_expr_priv(expr);
 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 != AF_INET && family != AF_INET6)
 150                 return -EAFNOSUPPORT;
 151         if (family != ctx->afi->family)
 152                 return -EOPNOTSUPP;
 153         priv->family = family;
 154
 155         if (tb[NFTA_NAT_REG_ADDR_MIN]) {
 156                 priv->sreg_addr_min =
 157                         ntohl(nla_get_be32(tb[NFTA_NAT_REG_ADDR_MIN]));
 158
 159                 err = nft_validate_input_register(priv->sreg_addr_min);
 160                 if (err < 0)
 161                         return err;
 162
 163                 if (tb[NFTA_NAT_REG_ADDR_MAX]) {
 164                         priv->sreg_addr_max =
 165                                 ntohl(nla_get_be32(tb[NFTA_NAT_REG_ADDR_MAX]));
 166
 167                         err = nft_validate_input_register(priv->sreg_addr_max);
 168                         if (err < 0)
 169                                 return err;
 170                 } else {
 171                         priv->sreg_addr_max = priv->sreg_addr_min;
 172                 }
 173         }
 174
 175         if (tb[NFTA_NAT_REG_PROTO_MIN]) {
 176                 priv->sreg_proto_min =
 177                         ntohl(nla_get_be32(tb[NFTA_NAT_REG_PROTO_MIN]));
 178
 179                 err = nft_validate_input_register(priv->sreg_proto_min);
 180                 if (err < 0)
 181                         return err;
 182
 183                 if (tb[NFTA_NAT_REG_PROTO_MAX]) {
 184                         priv->sreg_proto_max =
 185                                 ntohl(nla_get_be32(tb[NFTA_NAT_REG_PROTO_MAX]));
 186
 187                         err = nft_validate_input_register(priv->sreg_proto_max);
 188                         if (err < 0)
 189                                 return err;
 190                 } else {
 191                         priv->sreg_proto_max = priv->sreg_proto_min;
 192                 }
 193         }
 194
 195         if (tb[NFTA_NAT_FLAGS]) {
 196                 priv->flags = ntohl(nla_get_be32(tb[NFTA_NAT_FLAGS]));
 197                 if (priv->flags & ~NF_NAT_RANGE_MASK)
 198                         return -EINVAL;
 199         }
 200
 201         return 0;
 202 }
 203
 204 static int nft_nat_dump(struct sk_buff *skb, const struct nft_expr *expr)
 205 {
 206         const struct nft_nat *priv = nft_expr_priv(expr);
 207
 208         switch (priv->type) {
 209         case NF_NAT_MANIP_SRC:
 210                 if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_SNAT)))
 211                         goto nla_put_failure;
 212                 break;
 213         case NF_NAT_MANIP_DST:
 214                 if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_DNAT)))
 215                         goto nla_put_failure;
 216                 break;
 217         }
 218
 219         if (nla_put_be32(skb, NFTA_NAT_FAMILY, htonl(priv->family)))
 220                 goto nla_put_failure;
 221
 222         if (priv->sreg_addr_min) {
 223                 if (nla_put_be32(skb, NFTA_NAT_REG_ADDR_MIN,
 224                                  htonl(priv->sreg_addr_min)) ||
 225                     nla_put_be32(skb, NFTA_NAT_REG_ADDR_MAX,
 226                                  htonl(priv->sreg_addr_max)))
 227                         goto nla_put_failure;
 228         }
 229
 230         if (priv->sreg_proto_min) {
 231                 if (nla_put_be32(skb, NFTA_NAT_REG_PROTO_MIN,
 232                                  htonl(priv->sreg_proto_min)) ||
 233                     nla_put_be32(skb, NFTA_NAT_REG_PROTO_MAX,
 234                                  htonl(priv->sreg_proto_max)))
 235                         goto nla_put_failure;
 236         }
 237
 238         if (priv->flags != 0) {
 239                 if (nla_put_be32(skb, NFTA_NAT_FLAGS, htonl(priv->flags)))
 240                         goto nla_put_failure;
 241         }
 242
 243         return 0;
 244
 245 nla_put_failure:
 246         return -1;
 247 }
 248
 249 static struct nft_expr_type nft_nat_type;
 250 static const struct nft_expr_ops nft_nat_ops = {
 251         .type           = &nft_nat_type,
 252         .size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
 253         .eval           = nft_nat_eval,
 254         .init           = nft_nat_init,
 255         .dump           = nft_nat_dump,
 256         .validate       = nft_nat_validate,
 257 };
 258
 259 static struct nft_expr_type nft_nat_type __read_mostly = {
 260         .name           = "nat",
 261         .ops            = &nft_nat_ops,
 262         .policy         = nft_nat_policy,
 263         .maxattr        = NFTA_NAT_MAX,
 264         .owner          = THIS_MODULE,
 265 };
 266
 267 static int __init nft_nat_module_init(void)
 268 {
 269         return nft_register_expr(&nft_nat_type);
 270 }
 271
 272 static void __exit nft_nat_module_exit(void)
 273 {
 274         nft_unregister_expr(&nft_nat_type);
 275 }
 276
 277 module_init(nft_nat_module_init);
 278 module_exit(nft_nat_module_exit);
 279
 280 MODULE_LICENSE("GPL");
 281 MODULE_AUTHOR("Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>");
 282 MODULE_ALIAS_NFT_EXPR("nat");