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 = (__force __be16)
  69                                         data[priv->sreg_proto_min].data[0];
  70                 range.max_proto.all = (__force __be16)
  71                                         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_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
  92                         const struct nlattr * const tb[])
  93 {
  94         struct nft_nat *priv = nft_expr_priv(expr);
  95         u32 family;
  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         if (tb[NFTA_NAT_TYPE] == NULL ||
 103             (tb[NFTA_NAT_REG_ADDR_MIN] == NULL &&
 104              tb[NFTA_NAT_REG_PROTO_MIN] == NULL))
 105                 return -EINVAL;
 106
 107         switch (ntohl(nla_get_be32(tb[NFTA_NAT_TYPE]))) {
 108         case NFT_NAT_SNAT:
 109                 priv->type = NF_NAT_MANIP_SRC;
 110                 break;
 111         case NFT_NAT_DNAT:
 112                 priv->type = NF_NAT_MANIP_DST;
 113                 break;
 114         default:
 115                 return -EINVAL;
 116         }
 117
 118         if (tb[NFTA_NAT_FAMILY] == NULL)
 119                 return -EINVAL;
 120
 121         family = ntohl(nla_get_be32(tb[NFTA_NAT_FAMILY]));
 122         if (family != AF_INET && family != AF_INET6)
 123                 return -EAFNOSUPPORT;
 124         if (family != ctx->afi->family)
 125                 return -EOPNOTSUPP;
 126         priv->family = family;
 127
 128         if (tb[NFTA_NAT_REG_ADDR_MIN]) {
 129                 priv->sreg_addr_min =
 130                         ntohl(nla_get_be32(tb[NFTA_NAT_REG_ADDR_MIN]));
 131
 132                 err = nft_validate_input_register(priv->sreg_addr_min);
 133                 if (err < 0)
 134                         return err;
 135
 136                 if (tb[NFTA_NAT_REG_ADDR_MAX]) {
 137                         priv->sreg_addr_max =
 138                                 ntohl(nla_get_be32(tb[NFTA_NAT_REG_ADDR_MAX]));
 139
 140                         err = nft_validate_input_register(priv->sreg_addr_max);
 141                         if (err < 0)
 142                                 return err;
 143                 } else {
 144                         priv->sreg_addr_max = priv->sreg_addr_min;
 145                 }
 146         }
 147
 148         if (tb[NFTA_NAT_REG_PROTO_MIN]) {
 149                 priv->sreg_proto_min =
 150                         ntohl(nla_get_be32(tb[NFTA_NAT_REG_PROTO_MIN]));
 151
 152                 err = nft_validate_input_register(priv->sreg_proto_min);
 153                 if (err < 0)
 154                         return err;
 155
 156                 if (tb[NFTA_NAT_REG_PROTO_MAX]) {
 157                         priv->sreg_proto_max =
 158                                 ntohl(nla_get_be32(tb[NFTA_NAT_REG_PROTO_MAX]));
 159
 160                         err = nft_validate_input_register(priv->sreg_proto_max);
 161                         if (err < 0)
 162                                 return err;
 163                 } else {
 164                         priv->sreg_proto_max = priv->sreg_proto_min;
 165                 }
 166         }
 167
 168         if (tb[NFTA_NAT_FLAGS]) {
 169                 priv->flags = ntohl(nla_get_be32(tb[NFTA_NAT_FLAGS]));
 170                 if (priv->flags & ~NF_NAT_RANGE_MASK)
 171                         return -EINVAL;
 172         }
 173
 174         return 0;
 175 }
 176
 177 static int nft_nat_dump(struct sk_buff *skb, const struct nft_expr *expr)
 178 {
 179         const struct nft_nat *priv = nft_expr_priv(expr);
 180
 181         switch (priv->type) {
 182         case NF_NAT_MANIP_SRC:
 183                 if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_SNAT)))
 184                         goto nla_put_failure;
 185                 break;
 186         case NF_NAT_MANIP_DST:
 187                 if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_DNAT)))
 188                         goto nla_put_failure;
 189                 break;
 190         }
 191
 192         if (nla_put_be32(skb, NFTA_NAT_FAMILY, htonl(priv->family)))
 193                 goto nla_put_failure;
 194
 195         if (priv->sreg_addr_min) {
 196                 if (nla_put_be32(skb, NFTA_NAT_REG_ADDR_MIN,
 197                                  htonl(priv->sreg_addr_min)) ||
 198                     nla_put_be32(skb, NFTA_NAT_REG_ADDR_MAX,
 199                                  htonl(priv->sreg_addr_max)))
 200                         goto nla_put_failure;
 201         }
 202
 203         if (priv->sreg_proto_min) {
 204                 if (nla_put_be32(skb, NFTA_NAT_REG_PROTO_MIN,
 205                                  htonl(priv->sreg_proto_min)) ||
 206                     nla_put_be32(skb, NFTA_NAT_REG_PROTO_MAX,
 207                                  htonl(priv->sreg_proto_max)))
 208                         goto nla_put_failure;
 209         }
 210
 211         if (priv->flags != 0) {
 212                 if (nla_put_be32(skb, NFTA_NAT_FLAGS, htonl(priv->flags)))
 213                         goto nla_put_failure;
 214         }
 215
 216         return 0;
 217
 218 nla_put_failure:
 219         return -1;
 220 }
 221
 222 static int nft_nat_validate(const struct nft_ctx *ctx,
 223                             const struct nft_expr *expr,
 224                             const struct nft_data **data)
 225 {
 226         return nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
 227 }
 228
 229 static struct nft_expr_type nft_nat_type;
 230 static const struct nft_expr_ops nft_nat_ops = {
 231         .type           = &nft_nat_type,
 232         .size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
 233         .eval           = nft_nat_eval,
 234         .init           = nft_nat_init,
 235         .dump           = nft_nat_dump,
 236         .validate       = nft_nat_validate,
 237 };
 238
 239 static struct nft_expr_type nft_nat_type __read_mostly = {
 240         .name           = "nat",
 241         .ops            = &nft_nat_ops,
 242         .policy         = nft_nat_policy,
 243         .maxattr        = NFTA_NAT_MAX,
 244         .owner          = THIS_MODULE,
 245 };
 246
 247 static int __init nft_nat_module_init(void)
 248 {
 249         return nft_register_expr(&nft_nat_type);
 250 }
 251
 252 static void __exit nft_nat_module_exit(void)
 253 {
 254         nft_unregister_expr(&nft_nat_type);
 255 }
 256
 257 module_init(nft_nat_module_init);
 258 module_exit(nft_nat_module_exit);
 259
 260 MODULE_LICENSE("GPL");
 261 MODULE_AUTHOR("Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>");
 262 MODULE_ALIAS_NFT_EXPR("nat");