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         u8                      sreg_addr_min;
  25         u8                      sreg_addr_max;
  26         u8                      sreg_proto_min;
  27         u8                      sreg_proto_max;
  28         enum nf_nat_manip_type  type:8;
  29         u8                      family;
  30         u16                     flags;
  31 };
  32
  33 static void nft_nat_setup_addr(struct nf_nat_range2 *range,
  34                                const struct nft_regs *regs,
  35                                const struct nft_nat *priv)
  36 {
  37         switch (priv->family) {
  38         case AF_INET:
  39                 range->min_addr.ip = (__force __be32)
  40                                 regs->data[priv->sreg_addr_min];
  41                 range->max_addr.ip = (__force __be32)
  42                                 regs->data[priv->sreg_addr_max];
  43                 break;
  44         case AF_INET6:
  45                 memcpy(range->min_addr.ip6, &regs->data[priv->sreg_addr_min],
  46                        sizeof(range->min_addr.ip6));
  47                 memcpy(range->max_addr.ip6, &regs->data[priv->sreg_addr_max],
  48                        sizeof(range->max_addr.ip6));
  49                 break;
  50         }
  51 }
  52
  53 static void nft_nat_setup_proto(struct nf_nat_range2 *range,
  54                                 const struct nft_regs *regs,
  55                                 const struct nft_nat *priv)
  56 {
  57         range->min_proto.all = (__force __be16)
  58                 nft_reg_load16(&regs->data[priv->sreg_proto_min]);
  59         range->max_proto.all = (__force __be16)
  60                 nft_reg_load16(&regs->data[priv->sreg_proto_max]);
  61 }
  62
  63 static void nft_nat_setup_netmap(struct nf_nat_range2 *range,
  64                                  const struct nft_pktinfo *pkt,
  65                                  const struct nft_nat *priv)
  66 {
  67         struct sk_buff *skb = pkt->skb;
  68         union nf_inet_addr new_addr;
  69         __be32 netmask;
  70         int i, len = 0;
  71
  72         switch (priv->type) {
  73         case NFT_NAT_SNAT:
  74                 if (nft_pf(pkt) == NFPROTO_IPV4) {
  75                         new_addr.ip = ip_hdr(skb)->saddr;
  76                         len = sizeof(struct in_addr);
  77                 } else {
  78                         new_addr.in6 = ipv6_hdr(skb)->saddr;
  79                         len = sizeof(struct in6_addr);
  80                 }
  81                 break;
  82         case NFT_NAT_DNAT:
  83                 if (nft_pf(pkt) == NFPROTO_IPV4) {
  84                         new_addr.ip = ip_hdr(skb)->daddr;
  85                         len = sizeof(struct in_addr);
  86                 } else {
  87                         new_addr.in6 = ipv6_hdr(skb)->daddr;
  88                         len = sizeof(struct in6_addr);
  89                 }
  90                 break;
  91         }
  92
  93         for (i = 0; i < len / sizeof(__be32); i++) {
  94                 netmask = ~(range->min_addr.ip6[i] ^ range->max_addr.ip6[i]);
  95                 new_addr.ip6[i] &= ~netmask;
  96                 new_addr.ip6[i] |= range->min_addr.ip6[i] & netmask;
  97         }
  98
  99         range->min_addr = new_addr;
 100         range->max_addr = new_addr;
 101 }
 102
 103 static void nft_nat_eval(const struct nft_expr *expr,
 104                          struct nft_regs *regs,
 105                          const struct nft_pktinfo *pkt)
 106 {
 107         const struct nft_nat *priv = nft_expr_priv(expr);
 108         enum ip_conntrack_info ctinfo;
 109         struct nf_conn *ct = nf_ct_get(pkt->skb, &ctinfo);
 110         struct nf_nat_range2 range;
 111
 112         memset(&range, 0, sizeof(range));
 113
 114         if (priv->sreg_addr_min) {
 115                 nft_nat_setup_addr(&range, regs, priv);
 116                 if (priv->flags & NF_NAT_RANGE_NETMAP)
 117                         nft_nat_setup_netmap(&range, pkt, priv);
 118         }
 119
 120         if (priv->sreg_proto_min)
 121                 nft_nat_setup_proto(&range, regs, priv);
 122
 123         range.flags = priv->flags;
 124
 125         regs->verdict.code = nf_nat_setup_info(ct, &range, priv->type);
 126 }
 127
 128 static const struct nla_policy nft_nat_policy[NFTA_NAT_MAX + 1] = {
 129         [NFTA_NAT_TYPE]          = { .type = NLA_U32 },
 130         [NFTA_NAT_FAMILY]        = { .type = NLA_U32 },
 131         [NFTA_NAT_REG_ADDR_MIN]  = { .type = NLA_U32 },
 132         [NFTA_NAT_REG_ADDR_MAX]  = { .type = NLA_U32 },
 133         [NFTA_NAT_REG_PROTO_MIN] = { .type = NLA_U32 },
 134         [NFTA_NAT_REG_PROTO_MAX] = { .type = NLA_U32 },
 135         [NFTA_NAT_FLAGS]         =
 136                 NLA_POLICY_MASK(NLA_BE32, NF_NAT_RANGE_MASK),
 137 };
 138
 139 static int nft_nat_validate(const struct nft_ctx *ctx,
 140                             const struct nft_expr *expr,
 141                             const struct nft_data **data)
 142 {
 143         struct nft_nat *priv = nft_expr_priv(expr);
 144         int err;
 145
 146         if (ctx->family != NFPROTO_IPV4 &&
 147             ctx->family != NFPROTO_IPV6 &&
 148             ctx->family != NFPROTO_INET)
 149                 return -EOPNOTSUPP;
 150
 151         err = nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
 152         if (err < 0)
 153                 return err;
 154
 155         switch (priv->type) {
 156         case NFT_NAT_SNAT:
 157                 err = nft_chain_validate_hooks(ctx->chain,
 158                                                (1 << NF_INET_POST_ROUTING) |
 159                                                (1 << NF_INET_LOCAL_IN));
 160                 break;
 161         case NFT_NAT_DNAT:
 162                 err = nft_chain_validate_hooks(ctx->chain,
 163                                                (1 << NF_INET_PRE_ROUTING) |
 164                                                (1 << NF_INET_LOCAL_OUT));
 165                 break;
 166         }
 167
 168         return err;
 169 }
 170
 171 static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 172                         const struct nlattr * const tb[])
 173 {
 174         struct nft_nat *priv = nft_expr_priv(expr);
 175         unsigned int alen, plen;
 176         u32 family;
 177         int err;
 178
 179         if (tb[NFTA_NAT_TYPE] == NULL ||
 180             (tb[NFTA_NAT_REG_ADDR_MIN] == NULL &&
 181              tb[NFTA_NAT_REG_PROTO_MIN] == NULL))
 182                 return -EINVAL;
 183
 184         switch (ntohl(nla_get_be32(tb[NFTA_NAT_TYPE]))) {
 185         case NFT_NAT_SNAT:
 186                 priv->type = NF_NAT_MANIP_SRC;
 187                 break;
 188         case NFT_NAT_DNAT:
 189                 priv->type = NF_NAT_MANIP_DST;
 190                 break;
 191         default:
 192                 return -EOPNOTSUPP;
 193         }
 194
 195         if (tb[NFTA_NAT_FAMILY] == NULL)
 196                 return -EINVAL;
 197
 198         family = ntohl(nla_get_be32(tb[NFTA_NAT_FAMILY]));
 199         if (ctx->family != NFPROTO_INET && ctx->family != family)
 200                 return -EOPNOTSUPP;
 201
 202         switch (family) {
 203         case NFPROTO_IPV4:
 204                 alen = sizeof_field(struct nf_nat_range, min_addr.ip);
 205                 break;
 206         case NFPROTO_IPV6:
 207                 alen = sizeof_field(struct nf_nat_range, min_addr.ip6);
 208                 break;
 209         default:
 210                 if (tb[NFTA_NAT_REG_ADDR_MIN])
 211                         return -EAFNOSUPPORT;
 212                 break;
 213         }
 214         priv->family = family;
 215
 216         if (tb[NFTA_NAT_REG_ADDR_MIN]) {
 217                 err = nft_parse_register_load(tb[NFTA_NAT_REG_ADDR_MIN],
 218                                               &priv->sreg_addr_min, alen);
 219                 if (err < 0)
 220                         return err;
 221
 222                 if (tb[NFTA_NAT_REG_ADDR_MAX]) {
 223                         err = nft_parse_register_load(tb[NFTA_NAT_REG_ADDR_MAX],
 224                                                       &priv->sreg_addr_max,
 225                                                       alen);
 226                         if (err < 0)
 227                                 return err;
 228                 } else {
 229                         priv->sreg_addr_max = priv->sreg_addr_min;
 230                 }
 231
 232                 priv->flags |= NF_NAT_RANGE_MAP_IPS;
 233         }
 234
 235         plen = sizeof_field(struct nf_nat_range, min_proto.all);
 236         if (tb[NFTA_NAT_REG_PROTO_MIN]) {
 237                 err = nft_parse_register_load(tb[NFTA_NAT_REG_PROTO_MIN],
 238                                               &priv->sreg_proto_min, plen);
 239                 if (err < 0)
 240                         return err;
 241
 242                 if (tb[NFTA_NAT_REG_PROTO_MAX]) {
 243                         err = nft_parse_register_load(tb[NFTA_NAT_REG_PROTO_MAX],
 244                                                       &priv->sreg_proto_max,
 245                                                       plen);
 246                         if (err < 0)
 247                                 return err;
 248                 } else {
 249                         priv->sreg_proto_max = priv->sreg_proto_min;
 250                 }
 251
 252                 priv->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
 253         }
 254
 255         if (tb[NFTA_NAT_FLAGS])
 256                 priv->flags |= ntohl(nla_get_be32(tb[NFTA_NAT_FLAGS]));
 257
 258         return nf_ct_netns_get(ctx->net, family);
 259 }
 260
 261 static int nft_nat_dump(struct sk_buff *skb,
 262                         const struct nft_expr *expr, bool reset)
 263 {
 264         const struct nft_nat *priv = nft_expr_priv(expr);
 265
 266         switch (priv->type) {
 267         case NF_NAT_MANIP_SRC:
 268                 if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_SNAT)))
 269                         goto nla_put_failure;
 270                 break;
 271         case NF_NAT_MANIP_DST:
 272                 if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_DNAT)))
 273                         goto nla_put_failure;
 274                 break;
 275         }
 276
 277         if (nla_put_be32(skb, NFTA_NAT_FAMILY, htonl(priv->family)))
 278                 goto nla_put_failure;
 279
 280         if (priv->sreg_addr_min) {
 281                 if (nft_dump_register(skb, NFTA_NAT_REG_ADDR_MIN,
 282                                       priv->sreg_addr_min) ||
 283                     nft_dump_register(skb, NFTA_NAT_REG_ADDR_MAX,
 284                                       priv->sreg_addr_max))
 285                         goto nla_put_failure;
 286         }
 287
 288         if (priv->sreg_proto_min) {
 289                 if (nft_dump_register(skb, NFTA_NAT_REG_PROTO_MIN,
 290                                       priv->sreg_proto_min) ||
 291                     nft_dump_register(skb, NFTA_NAT_REG_PROTO_MAX,
 292                                       priv->sreg_proto_max))
 293                         goto nla_put_failure;
 294         }
 295
 296         if (priv->flags != 0) {
 297                 if (nla_put_be32(skb, NFTA_NAT_FLAGS, htonl(priv->flags)))
 298                         goto nla_put_failure;
 299         }
 300
 301         return 0;
 302
 303 nla_put_failure:
 304         return -1;
 305 }
 306
 307 static void
 308 nft_nat_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
 309 {
 310         const struct nft_nat *priv = nft_expr_priv(expr);
 311
 312         nf_ct_netns_put(ctx->net, priv->family);
 313 }
 314
 315 static struct nft_expr_type nft_nat_type;
 316 static const struct nft_expr_ops nft_nat_ops = {
 317         .type           = &nft_nat_type,
 318         .size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
 319         .eval           = nft_nat_eval,
 320         .init           = nft_nat_init,
 321         .destroy        = nft_nat_destroy,
 322         .dump           = nft_nat_dump,
 323         .validate       = nft_nat_validate,
 324         .reduce         = NFT_REDUCE_READONLY,
 325 };
 326
 327 static struct nft_expr_type nft_nat_type __read_mostly = {
 328         .name           = "nat",
 329         .ops            = &nft_nat_ops,
 330         .policy         = nft_nat_policy,
 331         .maxattr        = NFTA_NAT_MAX,
 332         .owner          = THIS_MODULE,
 333 };
 334
 335 #ifdef CONFIG_NF_TABLES_INET
 336 static void nft_nat_inet_eval(const struct nft_expr *expr,
 337                               struct nft_regs *regs,
 338                               const struct nft_pktinfo *pkt)
 339 {
 340         const struct nft_nat *priv = nft_expr_priv(expr);
 341
 342         if (priv->family == nft_pf(pkt) ||
 343             priv->family == NFPROTO_INET)
 344                 nft_nat_eval(expr, regs, pkt);
 345 }
 346
 347 static const struct nft_expr_ops nft_nat_inet_ops = {
 348         .type           = &nft_nat_type,
 349         .size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
 350         .eval           = nft_nat_inet_eval,
 351         .init           = nft_nat_init,
 352         .destroy        = nft_nat_destroy,
 353         .dump           = nft_nat_dump,
 354         .validate       = nft_nat_validate,
 355         .reduce         = NFT_REDUCE_READONLY,
 356 };
 357
 358 static struct nft_expr_type nft_inet_nat_type __read_mostly = {
 359         .name           = "nat",
 360         .family         = NFPROTO_INET,
 361         .ops            = &nft_nat_inet_ops,
 362         .policy         = nft_nat_policy,
 363         .maxattr        = NFTA_NAT_MAX,
 364         .owner          = THIS_MODULE,
 365 };
 366
 367 static int nft_nat_inet_module_init(void)
 368 {
 369         return nft_register_expr(&nft_inet_nat_type);
 370 }
 371
 372 static void nft_nat_inet_module_exit(void)
 373 {
 374         nft_unregister_expr(&nft_inet_nat_type);
 375 }
 376 #else
 377 static int nft_nat_inet_module_init(void) { return 0; }
 378 static void nft_nat_inet_module_exit(void) { }
 379 #endif
 380
 381 static int __init nft_nat_module_init(void)
 382 {
 383         int ret = nft_nat_inet_module_init();
 384
 385         if (ret)
 386                 return ret;
 387
 388         ret = nft_register_expr(&nft_nat_type);
 389         if (ret)
 390                 nft_nat_inet_module_exit();
 391
 392         return ret;
 393 }
 394
 395 static void __exit nft_nat_module_exit(void)
 396 {
 397         nft_nat_inet_module_exit();
 398         nft_unregister_expr(&nft_nat_type);
 399 }
 400
 401 module_init(nft_nat_module_init);
 402 module_exit(nft_nat_module_exit);
 403
 404 MODULE_LICENSE("GPL");
 405 MODULE_AUTHOR("Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>");
 406 MODULE_ALIAS_NFT_EXPR("nat");
 407 MODULE_DESCRIPTION("Network Address Translation support");