net/netfilter/nft_nat.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
   4  * Copyright (c) 2012 Pablo Neira Ayuso <pablo@netfilter.org>
   5  * Copyright (c) 2012 Intel Corporation
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/init.h>
  10 #include <linux/skbuff.h>
  11 #include <linux/ip.h>
  12 #include <linux/string.h>
  13 #include <linux/netlink.h>
  14 #include <linux/netfilter.h>
  15 #include <linux/netfilter_ipv4.h>
  16 #include <linux/netfilter/nfnetlink.h>
  17 #include <linux/netfilter/nf_tables.h>
  18 #include <net/netfilter/nf_conntrack.h>
  19 #include <net/netfilter/nf_nat.h>
  20 #include <net/netfilter/nf_tables.h>
  21 #include <net/ip.h>
  22
  23 struct nft_nat {
  24         enum nft_registers      sreg_addr_min:8;
  25         enum nft_registers      sreg_addr_max:8;
  26         enum nft_registers      sreg_proto_min:8;
  27         enum nft_registers      sreg_proto_max:8;
  28         enum nf_nat_manip_type  type:8;
  29         u8                      family;
  30         u16                     flags;
  31 };
  32
  33 static void nft_nat_eval(const struct nft_expr *expr,
  34                          struct nft_regs *regs,
  35                          const struct nft_pktinfo *pkt)
  36 {
  37         const struct nft_nat *priv = nft_expr_priv(expr);
  38         enum ip_conntrack_info ctinfo;
  39         struct nf_conn *ct = nf_ct_get(pkt->skb, &ctinfo);
  40         struct nf_nat_range2 range;
  41
  42         memset(&range, 0, sizeof(range));
  43         if (priv->sreg_addr_min) {
  44                 if (priv->family == AF_INET) {
  45                         range.min_addr.ip = (__force __be32)
  46                                         regs->data[priv->sreg_addr_min];
  47                         range.max_addr.ip = (__force __be32)
  48                                         regs->data[priv->sreg_addr_max];
  49
  50                 } else {
  51                         memcpy(range.min_addr.ip6,
  52                                &regs->data[priv->sreg_addr_min],
  53                                sizeof(range.min_addr.ip6));
  54                         memcpy(range.max_addr.ip6,
  55                                &regs->data[priv->sreg_addr_max],
  56                                sizeof(range.max_addr.ip6));
  57                 }
  58                 range.flags |= NF_NAT_RANGE_MAP_IPS;
  59         }
  60
  61         if (priv->sreg_proto_min) {
  62                 range.min_proto.all = (__force __be16)nft_reg_load16(
  63                         &regs->data[priv->sreg_proto_min]);
  64                 range.max_proto.all = (__force __be16)nft_reg_load16(
  65                         &regs->data[priv->sreg_proto_max]);
  66                 range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
  67         }
  68
  69         range.flags |= priv->flags;
  70
  71         regs->verdict.code = nf_nat_setup_info(ct, &range, priv->type);
  72 }
  73
  74 static const struct nla_policy nft_nat_policy[NFTA_NAT_MAX + 1] = {
  75         [NFTA_NAT_TYPE]          = { .type = NLA_U32 },
  76         [NFTA_NAT_FAMILY]        = { .type = NLA_U32 },
  77         [NFTA_NAT_REG_ADDR_MIN]  = { .type = NLA_U32 },
  78         [NFTA_NAT_REG_ADDR_MAX]  = { .type = NLA_U32 },
  79         [NFTA_NAT_REG_PROTO_MIN] = { .type = NLA_U32 },
  80         [NFTA_NAT_REG_PROTO_MAX] = { .type = NLA_U32 },
  81         [NFTA_NAT_FLAGS]         = { .type = NLA_U32 },
  82 };
  83
  84 static int nft_nat_validate(const struct nft_ctx *ctx,
  85                             const struct nft_expr *expr,
  86                             const struct nft_data **data)
  87 {
  88         struct nft_nat *priv = nft_expr_priv(expr);
  89         int err;
  90
  91         err = nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
  92         if (err < 0)
  93                 return err;
  94
  95         switch (priv->type) {
  96         case NFT_NAT_SNAT:
  97                 err = nft_chain_validate_hooks(ctx->chain,
  98                                                (1 << NF_INET_POST_ROUTING) |
  99                                                (1 << NF_INET_LOCAL_IN));
 100                 break;
 101         case NFT_NAT_DNAT:
 102                 err = nft_chain_validate_hooks(ctx->chain,
 103                                                (1 << NF_INET_PRE_ROUTING) |
 104                                                (1 << NF_INET_LOCAL_OUT));
 105                 break;
 106         }
 107
 108         return err;
 109 }
 110
 111 static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 112                         const struct nlattr * const tb[])
 113 {
 114         struct nft_nat *priv = nft_expr_priv(expr);
 115         unsigned int alen, plen;
 116         u32 family;
 117         int err;
 118
 119         if (tb[NFTA_NAT_TYPE] == NULL ||
 120             (tb[NFTA_NAT_REG_ADDR_MIN] == NULL &&
 121              tb[NFTA_NAT_REG_PROTO_MIN] == NULL))
 122                 return -EINVAL;
 123
 124         switch (ntohl(nla_get_be32(tb[NFTA_NAT_TYPE]))) {
 125         case NFT_NAT_SNAT:
 126                 priv->type = NF_NAT_MANIP_SRC;
 127                 break;
 128         case NFT_NAT_DNAT:
 129                 priv->type = NF_NAT_MANIP_DST;
 130                 break;
 131         default:
 132                 return -EINVAL;
 133         }
 134
 135         if (tb[NFTA_NAT_FAMILY] == NULL)
 136                 return -EINVAL;
 137
 138         family = ntohl(nla_get_be32(tb[NFTA_NAT_FAMILY]));
 139         if (ctx->family != NFPROTO_INET && ctx->family != family)
 140                 return -EOPNOTSUPP;
 141
 142         switch (family) {
 143         case NFPROTO_IPV4:
 144                 alen = sizeof_field(struct nf_nat_range, min_addr.ip);
 145                 break;
 146         case NFPROTO_IPV6:
 147                 alen = sizeof_field(struct nf_nat_range, min_addr.ip6);
 148                 break;
 149         default:
 150                 return -EAFNOSUPPORT;
 151         }
 152         priv->family = family;
 153
 154         if (tb[NFTA_NAT_REG_ADDR_MIN]) {
 155                 priv->sreg_addr_min =
 156                         nft_parse_register(tb[NFTA_NAT_REG_ADDR_MIN]);
 157                 err = nft_validate_register_load(priv->sreg_addr_min, alen);
 158                 if (err < 0)
 159                         return err;
 160
 161                 if (tb[NFTA_NAT_REG_ADDR_MAX]) {
 162                         priv->sreg_addr_max =
 163                                 nft_parse_register(tb[NFTA_NAT_REG_ADDR_MAX]);
 164
 165                         err = nft_validate_register_load(priv->sreg_addr_max,
 166                                                          alen);
 167                         if (err < 0)
 168                                 return err;
 169                 } else {
 170                         priv->sreg_addr_max = priv->sreg_addr_min;
 171                 }
 172         }
 173
 174         plen = sizeof_field(struct nf_nat_range, min_addr.all);
 175         if (tb[NFTA_NAT_REG_PROTO_MIN]) {
 176                 priv->sreg_proto_min =
 177                         nft_parse_register(tb[NFTA_NAT_REG_PROTO_MIN]);
 178
 179                 err = nft_validate_register_load(priv->sreg_proto_min, plen);
 180                 if (err < 0)
 181                         return err;
 182
 183                 if (tb[NFTA_NAT_REG_PROTO_MAX]) {
 184                         priv->sreg_proto_max =
 185                                 nft_parse_register(tb[NFTA_NAT_REG_PROTO_MAX]);
 186
 187                         err = nft_validate_register_load(priv->sreg_proto_max,
 188                                                          plen);
 189                         if (err < 0)
 190                                 return err;
 191                 } else {
 192                         priv->sreg_proto_max = priv->sreg_proto_min;
 193                 }
 194         }
 195
 196         if (tb[NFTA_NAT_FLAGS]) {
 197                 priv->flags = ntohl(nla_get_be32(tb[NFTA_NAT_FLAGS]));
 198                 if (priv->flags & ~NF_NAT_RANGE_MASK)
 199                         return -EINVAL;
 200         }
 201
 202         return nf_ct_netns_get(ctx->net, family);
 203 }
 204
 205 static int nft_nat_dump(struct sk_buff *skb, const struct nft_expr *expr)
 206 {
 207         const struct nft_nat *priv = nft_expr_priv(expr);
 208
 209         switch (priv->type) {
 210         case NF_NAT_MANIP_SRC:
 211                 if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_SNAT)))
 212                         goto nla_put_failure;
 213                 break;
 214         case NF_NAT_MANIP_DST:
 215                 if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_DNAT)))
 216                         goto nla_put_failure;
 217                 break;
 218         }
 219
 220         if (nla_put_be32(skb, NFTA_NAT_FAMILY, htonl(priv->family)))
 221                 goto nla_put_failure;
 222
 223         if (priv->sreg_addr_min) {
 224                 if (nft_dump_register(skb, NFTA_NAT_REG_ADDR_MIN,
 225                                       priv->sreg_addr_min) ||
 226                     nft_dump_register(skb, NFTA_NAT_REG_ADDR_MAX,
 227                                       priv->sreg_addr_max))
 228                         goto nla_put_failure;
 229         }
 230
 231         if (priv->sreg_proto_min) {
 232                 if (nft_dump_register(skb, NFTA_NAT_REG_PROTO_MIN,
 233                                       priv->sreg_proto_min) ||
 234                     nft_dump_register(skb, NFTA_NAT_REG_PROTO_MAX,
 235                                       priv->sreg_proto_max))
 236                         goto nla_put_failure;
 237         }
 238
 239         if (priv->flags != 0) {
 240                 if (nla_put_be32(skb, NFTA_NAT_FLAGS, htonl(priv->flags)))
 241                         goto nla_put_failure;
 242         }
 243
 244         return 0;
 245
 246 nla_put_failure:
 247         return -1;
 248 }
 249
 250 static void
 251 nft_nat_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
 252 {
 253         const struct nft_nat *priv = nft_expr_priv(expr);
 254
 255         nf_ct_netns_put(ctx->net, priv->family);
 256 }
 257
 258 static struct nft_expr_type nft_nat_type;
 259 static const struct nft_expr_ops nft_nat_ops = {
 260         .type           = &nft_nat_type,
 261         .size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
 262         .eval           = nft_nat_eval,
 263         .init           = nft_nat_init,
 264         .destroy        = nft_nat_destroy,
 265         .dump           = nft_nat_dump,
 266         .validate       = nft_nat_validate,
 267 };
 268
 269 static struct nft_expr_type nft_nat_type __read_mostly = {
 270         .name           = "nat",
 271         .ops            = &nft_nat_ops,
 272         .policy         = nft_nat_policy,
 273         .maxattr        = NFTA_NAT_MAX,
 274         .owner          = THIS_MODULE,
 275 };
 276
 277 #ifdef CONFIG_NF_TABLES_INET
 278 static void nft_nat_inet_eval(const struct nft_expr *expr,
 279                               struct nft_regs *regs,
 280                               const struct nft_pktinfo *pkt)
 281 {
 282         const struct nft_nat *priv = nft_expr_priv(expr);
 283
 284         if (priv->family == nft_pf(pkt))
 285                 nft_nat_eval(expr, regs, pkt);
 286 }
 287
 288 static const struct nft_expr_ops nft_nat_inet_ops = {
 289         .type           = &nft_nat_type,
 290         .size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
 291         .eval           = nft_nat_inet_eval,
 292         .init           = nft_nat_init,
 293         .destroy        = nft_nat_destroy,
 294         .dump           = nft_nat_dump,
 295         .validate       = nft_nat_validate,
 296 };
 297
 298 static struct nft_expr_type nft_inet_nat_type __read_mostly = {
 299         .name           = "nat",
 300         .family         = NFPROTO_INET,
 301         .ops            = &nft_nat_inet_ops,
 302         .policy         = nft_nat_policy,
 303         .maxattr        = NFTA_NAT_MAX,
 304         .owner          = THIS_MODULE,
 305 };
 306
 307 static int nft_nat_inet_module_init(void)
 308 {
 309         return nft_register_expr(&nft_inet_nat_type);
 310 }
 311
 312 static void nft_nat_inet_module_exit(void)
 313 {
 314         nft_unregister_expr(&nft_inet_nat_type);
 315 }
 316 #else
 317 static int nft_nat_inet_module_init(void) { return 0; }
 318 static void nft_nat_inet_module_exit(void) { }
 319 #endif
 320
 321 static int __init nft_nat_module_init(void)
 322 {
 323         int ret = nft_nat_inet_module_init();
 324
 325         if (ret)
 326                 return ret;
 327
 328         ret = nft_register_expr(&nft_nat_type);
 329         if (ret)
 330                 nft_nat_inet_module_exit();
 331
 332         return ret;
 333 }
 334
 335 static void __exit nft_nat_module_exit(void)
 336 {
 337         nft_nat_inet_module_exit();
 338         nft_unregister_expr(&nft_nat_type);
 339 }
 340
 341 module_init(nft_nat_module_init);
 342 module_exit(nft_nat_module_exit);
 343
 344 MODULE_LICENSE("GPL");
 345 MODULE_AUTHOR("Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>");
 346 MODULE_ALIAS_NFT_EXPR("nat");