net/netfilter/nft_nat.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2008-2009 Patrick McHardy <[email protected]>
   4  * Copyright (c) 2012 Pablo Neira Ayuso <[email protected]>
   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         err = nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
 146         if (err < 0)
 147                 return err;
 148
 149         switch (priv->type) {
 150         case NFT_NAT_SNAT:
 151                 err = nft_chain_validate_hooks(ctx->chain,
 152                                                (1 << NF_INET_POST_ROUTING) |
 153                                                (1 << NF_INET_LOCAL_IN));
 154                 break;
 155         case NFT_NAT_DNAT:
 156                 err = nft_chain_validate_hooks(ctx->chain,
 157                                                (1 << NF_INET_PRE_ROUTING) |
 158                                                (1 << NF_INET_LOCAL_OUT));
 159                 break;
 160         }
 161
 162         return err;
 163 }
 164
 165 static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 166                         const struct nlattr * const tb[])
 167 {
 168         struct nft_nat *priv = nft_expr_priv(expr);
 169         unsigned int alen, plen;
 170         u32 family;
 171         int err;
 172
 173         if (tb[NFTA_NAT_TYPE] == NULL ||
 174             (tb[NFTA_NAT_REG_ADDR_MIN] == NULL &&
 175              tb[NFTA_NAT_REG_PROTO_MIN] == NULL))
 176                 return -EINVAL;
 177
 178         switch (ntohl(nla_get_be32(tb[NFTA_NAT_TYPE]))) {
 179         case NFT_NAT_SNAT:
 180                 priv->type = NF_NAT_MANIP_SRC;
 181                 break;
 182         case NFT_NAT_DNAT:
 183                 priv->type = NF_NAT_MANIP_DST;
 184                 break;
 185         default:
 186                 return -EOPNOTSUPP;
 187         }
 188
 189         if (tb[NFTA_NAT_FAMILY] == NULL)
 190                 return -EINVAL;
 191
 192         family = ntohl(nla_get_be32(tb[NFTA_NAT_FAMILY]));
 193         if (ctx->family != NFPROTO_INET && ctx->family != family)
 194                 return -EOPNOTSUPP;
 195
 196         switch (family) {
 197         case NFPROTO_IPV4:
 198                 alen = sizeof_field(struct nf_nat_range, min_addr.ip);
 199                 break;
 200         case NFPROTO_IPV6:
 201                 alen = sizeof_field(struct nf_nat_range, min_addr.ip6);
 202                 break;
 203         default:
 204                 if (tb[NFTA_NAT_REG_ADDR_MIN])
 205                         return -EAFNOSUPPORT;
 206                 break;
 207         }
 208         priv->family = family;
 209
 210         if (tb[NFTA_NAT_REG_ADDR_MIN]) {
 211                 err = nft_parse_register_load(tb[NFTA_NAT_REG_ADDR_MIN],
 212                                               &priv->sreg_addr_min, alen);
 213                 if (err < 0)
 214                         return err;
 215
 216                 if (tb[NFTA_NAT_REG_ADDR_MAX]) {
 217                         err = nft_parse_register_load(tb[NFTA_NAT_REG_ADDR_MAX],
 218                                                       &priv->sreg_addr_max,
 219                                                       alen);
 220                         if (err < 0)
 221                                 return err;
 222                 } else {
 223                         priv->sreg_addr_max = priv->sreg_addr_min;
 224                 }
 225
 226                 priv->flags |= NF_NAT_RANGE_MAP_IPS;
 227         }
 228
 229         plen = sizeof_field(struct nf_nat_range, min_addr.all);
 230         if (tb[NFTA_NAT_REG_PROTO_MIN]) {
 231                 err = nft_parse_register_load(tb[NFTA_NAT_REG_PROTO_MIN],
 232                                               &priv->sreg_proto_min, plen);
 233                 if (err < 0)
 234                         return err;
 235
 236                 if (tb[NFTA_NAT_REG_PROTO_MAX]) {
 237                         err = nft_parse_register_load(tb[NFTA_NAT_REG_PROTO_MAX],
 238                                                       &priv->sreg_proto_max,
 239                                                       plen);
 240                         if (err < 0)
 241                                 return err;
 242                 } else {
 243                         priv->sreg_proto_max = priv->sreg_proto_min;
 244                 }
 245
 246                 priv->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
 247         }
 248
 249         if (tb[NFTA_NAT_FLAGS]) {
 250                 priv->flags |= ntohl(nla_get_be32(tb[NFTA_NAT_FLAGS]));
 251                 if (priv->flags & ~NF_NAT_RANGE_MASK)
 252                         return -EOPNOTSUPP;
 253         }
 254
 255         return nf_ct_netns_get(ctx->net, family);
 256 }
 257
 258 static int nft_nat_dump(struct sk_buff *skb,
 259                         const struct nft_expr *expr, bool reset)
 260 {
 261         const struct nft_nat *priv = nft_expr_priv(expr);
 262
 263         switch (priv->type) {
 264         case NF_NAT_MANIP_SRC:
 265                 if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_SNAT)))
 266                         goto nla_put_failure;
 267                 break;
 268         case NF_NAT_MANIP_DST:
 269                 if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_DNAT)))
 270                         goto nla_put_failure;
 271                 break;
 272         }
 273
 274         if (nla_put_be32(skb, NFTA_NAT_FAMILY, htonl(priv->family)))
 275                 goto nla_put_failure;
 276
 277         if (priv->sreg_addr_min) {
 278                 if (nft_dump_register(skb, NFTA_NAT_REG_ADDR_MIN,
 279                                       priv->sreg_addr_min) ||
 280                     nft_dump_register(skb, NFTA_NAT_REG_ADDR_MAX,
 281                                       priv->sreg_addr_max))
 282                         goto nla_put_failure;
 283         }
 284
 285         if (priv->sreg_proto_min) {
 286                 if (nft_dump_register(skb, NFTA_NAT_REG_PROTO_MIN,
 287                                       priv->sreg_proto_min) ||
 288                     nft_dump_register(skb, NFTA_NAT_REG_PROTO_MAX,
 289                                       priv->sreg_proto_max))
 290                         goto nla_put_failure;
 291         }
 292
 293         if (priv->flags != 0) {
 294                 if (nla_put_be32(skb, NFTA_NAT_FLAGS, htonl(priv->flags)))
 295                         goto nla_put_failure;
 296         }
 297
 298         return 0;
 299
 300 nla_put_failure:
 301         return -1;
 302 }
 303
 304 static void
 305 nft_nat_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
 306 {
 307         const struct nft_nat *priv = nft_expr_priv(expr);
 308
 309         nf_ct_netns_put(ctx->net, priv->family);
 310 }
 311
 312 static struct nft_expr_type nft_nat_type;
 313 static const struct nft_expr_ops nft_nat_ops = {
 314         .type           = &nft_nat_type,
 315         .size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
 316         .eval           = nft_nat_eval,
 317         .init           = nft_nat_init,
 318         .destroy        = nft_nat_destroy,
 319         .dump           = nft_nat_dump,
 320         .validate       = nft_nat_validate,
 321         .reduce         = NFT_REDUCE_READONLY,
 322 };
 323
 324 static struct nft_expr_type nft_nat_type __read_mostly = {
 325         .name           = "nat",
 326         .ops            = &nft_nat_ops,
 327         .policy         = nft_nat_policy,
 328         .maxattr        = NFTA_NAT_MAX,
 329         .owner          = THIS_MODULE,
 330 };
 331
 332 #ifdef CONFIG_NF_TABLES_INET
 333 static void nft_nat_inet_eval(const struct nft_expr *expr,
 334                               struct nft_regs *regs,
 335                               const struct nft_pktinfo *pkt)
 336 {
 337         const struct nft_nat *priv = nft_expr_priv(expr);
 338
 339         if (priv->family == nft_pf(pkt) ||
 340             priv->family == NFPROTO_INET)
 341                 nft_nat_eval(expr, regs, pkt);
 342 }
 343
 344 static const struct nft_expr_ops nft_nat_inet_ops = {
 345         .type           = &nft_nat_type,
 346         .size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
 347         .eval           = nft_nat_inet_eval,
 348         .init           = nft_nat_init,
 349         .destroy        = nft_nat_destroy,
 350         .dump           = nft_nat_dump,
 351         .validate       = nft_nat_validate,
 352         .reduce         = NFT_REDUCE_READONLY,
 353 };
 354
 355 static struct nft_expr_type nft_inet_nat_type __read_mostly = {
 356         .name           = "nat",
 357         .family         = NFPROTO_INET,
 358         .ops            = &nft_nat_inet_ops,
 359         .policy         = nft_nat_policy,
 360         .maxattr        = NFTA_NAT_MAX,
 361         .owner          = THIS_MODULE,
 362 };
 363
 364 static int nft_nat_inet_module_init(void)
 365 {
 366         return nft_register_expr(&nft_inet_nat_type);
 367 }
 368
 369 static void nft_nat_inet_module_exit(void)
 370 {
 371         nft_unregister_expr(&nft_inet_nat_type);
 372 }
 373 #else
 374 static int nft_nat_inet_module_init(void) { return 0; }
 375 static void nft_nat_inet_module_exit(void) { }
 376 #endif
 377
 378 static int __init nft_nat_module_init(void)
 379 {
 380         int ret = nft_nat_inet_module_init();
 381
 382         if (ret)
 383                 return ret;
 384
 385         ret = nft_register_expr(&nft_nat_type);
 386         if (ret)
 387                 nft_nat_inet_module_exit();
 388
 389         return ret;
 390 }
 391
 392 static void __exit nft_nat_module_exit(void)
 393 {
 394         nft_nat_inet_module_exit();
 395         nft_unregister_expr(&nft_nat_type);
 396 }
 397
 398 module_init(nft_nat_module_init);
 399 module_exit(nft_nat_module_exit);
 400
 401 MODULE_LICENSE("GPL");
 402 MODULE_AUTHOR("Tomasz Bursztyka <[email protected]>");
 403 MODULE_ALIAS_NFT_EXPR("nat");
 404 MODULE_DESCRIPTION("Network Address Translation support");