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]         = { .type = NLA_U32 },
 136 };
 137
 138 static int nft_nat_validate(const struct nft_ctx *ctx,
 139                             const struct nft_expr *expr,
 140                             const struct nft_data **data)
 141 {
 142         struct nft_nat *priv = nft_expr_priv(expr);
 143         int err;
 144
 145         if (ctx->family != NFPROTO_IPV4 &&
 146             ctx->family != NFPROTO_IPV6 &&
 147             ctx->family != NFPROTO_INET)
 148                 return -EOPNOTSUPP;
 149
 150         err = nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
 151         if (err < 0)
 152                 return err;
 153
 154         switch (priv->type) {
 155         case NFT_NAT_SNAT:
 156                 err = nft_chain_validate_hooks(ctx->chain,
 157                                                (1 << NF_INET_POST_ROUTING) |
 158                                                (1 << NF_INET_LOCAL_IN));
 159                 break;
 160         case NFT_NAT_DNAT:
 161                 err = nft_chain_validate_hooks(ctx->chain,
 162                                                (1 << NF_INET_PRE_ROUTING) |
 163                                                (1 << NF_INET_LOCAL_OUT));
 164                 break;
 165         }
 166
 167         return err;
 168 }
 169
 170 static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 171                         const struct nlattr * const tb[])
 172 {
 173         struct nft_nat *priv = nft_expr_priv(expr);
 174         unsigned int alen, plen;
 175         u32 family;
 176         int err;
 177
 178         if (tb[NFTA_NAT_TYPE] == NULL ||
 179             (tb[NFTA_NAT_REG_ADDR_MIN] == NULL &&
 180              tb[NFTA_NAT_REG_PROTO_MIN] == NULL))
 181                 return -EINVAL;
 182
 183         switch (ntohl(nla_get_be32(tb[NFTA_NAT_TYPE]))) {
 184         case NFT_NAT_SNAT:
 185                 priv->type = NF_NAT_MANIP_SRC;
 186                 break;
 187         case NFT_NAT_DNAT:
 188                 priv->type = NF_NAT_MANIP_DST;
 189                 break;
 190         default:
 191                 return -EOPNOTSUPP;
 192         }
 193
 194         if (tb[NFTA_NAT_FAMILY] == NULL)
 195                 return -EINVAL;
 196
 197         family = ntohl(nla_get_be32(tb[NFTA_NAT_FAMILY]));
 198         if (ctx->family != NFPROTO_INET && ctx->family != family)
 199                 return -EOPNOTSUPP;
 200
 201         switch (family) {
 202         case NFPROTO_IPV4:
 203                 alen = sizeof_field(struct nf_nat_range, min_addr.ip);
 204                 break;
 205         case NFPROTO_IPV6:
 206                 alen = sizeof_field(struct nf_nat_range, min_addr.ip6);
 207                 break;
 208         default:
 209                 if (tb[NFTA_NAT_REG_ADDR_MIN])
 210                         return -EAFNOSUPPORT;
 211                 break;
 212         }
 213         priv->family = family;
 214
 215         if (tb[NFTA_NAT_REG_ADDR_MIN]) {
 216                 err = nft_parse_register_load(tb[NFTA_NAT_REG_ADDR_MIN],
 217                                               &priv->sreg_addr_min, alen);
 218                 if (err < 0)
 219                         return err;
 220
 221                 if (tb[NFTA_NAT_REG_ADDR_MAX]) {
 222                         err = nft_parse_register_load(tb[NFTA_NAT_REG_ADDR_MAX],
 223                                                       &priv->sreg_addr_max,
 224                                                       alen);
 225                         if (err < 0)
 226                                 return err;
 227                 } else {
 228                         priv->sreg_addr_max = priv->sreg_addr_min;
 229                 }
 230
 231                 priv->flags |= NF_NAT_RANGE_MAP_IPS;
 232         }
 233
 234         plen = sizeof_field(struct nf_nat_range, min_proto.all);
 235         if (tb[NFTA_NAT_REG_PROTO_MIN]) {
 236                 err = nft_parse_register_load(tb[NFTA_NAT_REG_PROTO_MIN],
 237                                               &priv->sreg_proto_min, plen);
 238                 if (err < 0)
 239                         return err;
 240
 241                 if (tb[NFTA_NAT_REG_PROTO_MAX]) {
 242                         err = nft_parse_register_load(tb[NFTA_NAT_REG_PROTO_MAX],
 243                                                       &priv->sreg_proto_max,
 244                                                       plen);
 245                         if (err < 0)
 246                                 return err;
 247                 } else {
 248                         priv->sreg_proto_max = priv->sreg_proto_min;
 249                 }
 250
 251                 priv->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
 252         }
 253
 254         if (tb[NFTA_NAT_FLAGS]) {
 255                 priv->flags |= ntohl(nla_get_be32(tb[NFTA_NAT_FLAGS]));
 256                 if (priv->flags & ~NF_NAT_RANGE_MASK)
 257                         return -EOPNOTSUPP;
 258         }
 259
 260         return nf_ct_netns_get(ctx->net, family);
 261 }
 262
 263 static int nft_nat_dump(struct sk_buff *skb, const struct nft_expr *expr)
 264 {
 265         const struct nft_nat *priv = nft_expr_priv(expr);
 266
 267         switch (priv->type) {
 268         case NF_NAT_MANIP_SRC:
 269                 if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_SNAT)))
 270                         goto nla_put_failure;
 271                 break;
 272         case NF_NAT_MANIP_DST:
 273                 if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_DNAT)))
 274                         goto nla_put_failure;
 275                 break;
 276         }
 277
 278         if (nla_put_be32(skb, NFTA_NAT_FAMILY, htonl(priv->family)))
 279                 goto nla_put_failure;
 280
 281         if (priv->sreg_addr_min) {
 282                 if (nft_dump_register(skb, NFTA_NAT_REG_ADDR_MIN,
 283                                       priv->sreg_addr_min) ||
 284                     nft_dump_register(skb, NFTA_NAT_REG_ADDR_MAX,
 285                                       priv->sreg_addr_max))
 286                         goto nla_put_failure;
 287         }
 288
 289         if (priv->sreg_proto_min) {
 290                 if (nft_dump_register(skb, NFTA_NAT_REG_PROTO_MIN,
 291                                       priv->sreg_proto_min) ||
 292                     nft_dump_register(skb, NFTA_NAT_REG_PROTO_MAX,
 293                                       priv->sreg_proto_max))
 294                         goto nla_put_failure;
 295         }
 296
 297         if (priv->flags != 0) {
 298                 if (nla_put_be32(skb, NFTA_NAT_FLAGS, htonl(priv->flags)))
 299                         goto nla_put_failure;
 300         }
 301
 302         return 0;
 303
 304 nla_put_failure:
 305         return -1;
 306 }
 307
 308 static void
 309 nft_nat_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
 310 {
 311         const struct nft_nat *priv = nft_expr_priv(expr);
 312
 313         nf_ct_netns_put(ctx->net, priv->family);
 314 }
 315
 316 static struct nft_expr_type nft_nat_type;
 317 static const struct nft_expr_ops nft_nat_ops = {
 318         .type           = &nft_nat_type,
 319         .size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
 320         .eval           = nft_nat_eval,
 321         .init           = nft_nat_init,
 322         .destroy        = nft_nat_destroy,
 323         .dump           = nft_nat_dump,
 324         .validate       = nft_nat_validate,
 325         .reduce         = NFT_REDUCE_READONLY,
 326 };
 327
 328 static struct nft_expr_type nft_nat_type __read_mostly = {
 329         .name           = "nat",
 330         .ops            = &nft_nat_ops,
 331         .policy         = nft_nat_policy,
 332         .maxattr        = NFTA_NAT_MAX,
 333         .owner          = THIS_MODULE,
 334 };
 335
 336 #ifdef CONFIG_NF_TABLES_INET
 337 static void nft_nat_inet_eval(const struct nft_expr *expr,
 338                               struct nft_regs *regs,
 339                               const struct nft_pktinfo *pkt)
 340 {
 341         const struct nft_nat *priv = nft_expr_priv(expr);
 342
 343         if (priv->family == nft_pf(pkt) ||
 344             priv->family == NFPROTO_INET)
 345                 nft_nat_eval(expr, regs, pkt);
 346 }
 347
 348 static const struct nft_expr_ops nft_nat_inet_ops = {
 349         .type           = &nft_nat_type,
 350         .size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
 351         .eval           = nft_nat_inet_eval,
 352         .init           = nft_nat_init,
 353         .destroy        = nft_nat_destroy,
 354         .dump           = nft_nat_dump,
 355         .validate       = nft_nat_validate,
 356         .reduce         = NFT_REDUCE_READONLY,
 357 };
 358
 359 static struct nft_expr_type nft_inet_nat_type __read_mostly = {
 360         .name           = "nat",
 361         .family         = NFPROTO_INET,
 362         .ops            = &nft_nat_inet_ops,
 363         .policy         = nft_nat_policy,
 364         .maxattr        = NFTA_NAT_MAX,
 365         .owner          = THIS_MODULE,
 366 };
 367
 368 static int nft_nat_inet_module_init(void)
 369 {
 370         return nft_register_expr(&nft_inet_nat_type);
 371 }
 372
 373 static void nft_nat_inet_module_exit(void)
 374 {
 375         nft_unregister_expr(&nft_inet_nat_type);
 376 }
 377 #else
 378 static int nft_nat_inet_module_init(void) { return 0; }
 379 static void nft_nat_inet_module_exit(void) { }
 380 #endif
 381
 382 static int __init nft_nat_module_init(void)
 383 {
 384         int ret = nft_nat_inet_module_init();
 385
 386         if (ret)
 387                 return ret;
 388
 389         ret = nft_register_expr(&nft_nat_type);
 390         if (ret)
 391                 nft_nat_inet_module_exit();
 392
 393         return ret;
 394 }
 395
 396 static void __exit nft_nat_module_exit(void)
 397 {
 398         nft_nat_inet_module_exit();
 399         nft_unregister_expr(&nft_nat_type);
 400 }
 401
 402 module_init(nft_nat_module_init);
 403 module_exit(nft_nat_module_exit);
 404
 405 MODULE_LICENSE("GPL");
 406 MODULE_AUTHOR("Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>");
 407 MODULE_ALIAS_NFT_EXPR("nat");
 408 MODULE_DESCRIPTION("Network Address Translation support");