snats.c

   1 /*
   2  * firewall3 - 3rd OpenWrt UCI firewall implementation
   3  *
   4  *   Copyright (C) 2014 Jo-Philipp Wich <jo@mein.io>
   5  *
   6  * Permission to use, copy, modify, and/or distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #include "snats.h"
  20
  21
  22 const struct fw3_option fw3_snat_opts[] = {
  23         FW3_OPT("enabled",             bool,      snat,     enabled),
  24
  25         FW3_OPT("name",                string,    snat,     name),
  26         FW3_OPT("family",              family,    snat,     family),
  27
  28         FW3_OPT("src",                 device,    snat,     src),
  29         FW3_OPT("device",              string,    snat,     device),
  30
  31         FW3_OPT("ipset",               setmatch,  snat,     ipset),
  32
  33         FW3_LIST("proto",              protocol,  snat,     proto),
  34
  35         FW3_OPT("src_ip",              network,   snat,     ip_src),
  36         FW3_OPT("src_port",            port,      snat,     port_src),
  37
  38         FW3_OPT("snat_ip",             network,   snat,     ip_snat),
  39         FW3_OPT("snat_port",           port,      snat,     port_snat),
  40
  41         FW3_OPT("dest_ip",             network,   snat,     ip_dest),
  42         FW3_OPT("dest_port",           port,      snat,     port_dest),
  43
  44         FW3_OPT("extra",               string,    snat,     extra),
  45
  46         FW3_OPT("limit",               limit,     snat,     limit),
  47         FW3_OPT("limit_burst",         int,       snat,     limit.burst),
  48
  49         FW3_OPT("connlimit_ports",     bool,      snat,     connlimit_ports),
  50
  51         FW3_OPT("utc_time",            bool,      snat,     time.utc),
  52         FW3_OPT("start_date",          date,      snat,     time.datestart),
  53         FW3_OPT("stop_date",           date,      snat,     time.datestop),
  54         FW3_OPT("start_time",          time,      snat,     time.timestart),
  55         FW3_OPT("stop_time",           time,      snat,     time.timestop),
  56         FW3_OPT("weekdays",            weekdays,  snat,     time.weekdays),
  57         FW3_OPT("monthdays",           monthdays, snat,     time.monthdays),
  58
  59         FW3_OPT("mark",                mark,      snat,     mark),
  60
  61         FW3_OPT("target",              target,    snat,     target),
  62
  63         { }
  64 };
  65
  66
  67 static bool
  68 check_families(struct uci_element *e, struct fw3_snat *r)
  69 {
  70         if (r->family == FW3_FAMILY_ANY)
  71                 return true;
  72
  73         if (r->_src && r->_src->family && r->_src->family != r->family)
  74         {
  75                 warn_section("nat", r, e, "refers to source zone with different family");
  76                 return false;
  77         }
  78
  79         if (r->ipset.ptr && r->ipset.ptr->family &&
  80             r->ipset.ptr->family != r->family)
  81         {
  82                 warn_section("nat", r, e, "refers to ipset with different family");
  83                 return false;
  84         }
  85
  86         if (r->ip_src.family && r->ip_src.family != r->family)
  87         {
  88                 warn_section("nat", r, e, "uses source ip with different family");
  89                 return false;
  90         }
  91
  92         if (r->ip_dest.family && r->ip_dest.family != r->family)
  93         {
  94                 warn_section("nat", r, e, "uses destination ip with different family");
  95                 return false;
  96         }
  97
  98         if (r->ip_snat.family && r->ip_snat.family != r->family)
  99         {
 100                 warn_section("nat", r, e, "uses snat ip with different family");
 101                 return false;
 102         }
 103
 104         return true;
 105 }
 106
 107
 108 static struct fw3_snat*
 109 alloc_snat(struct fw3_state *state)
 110 {
 111         struct fw3_snat *snat = calloc(1, sizeof(*snat));
 112
 113         if (snat) {
 114                 INIT_LIST_HEAD(&snat->proto);
 115                 list_add_tail(&snat->list, &state->snats);
 116                 snat->enabled = true;
 117         }
 118
 119         return snat;
 120 }
 121
 122 static bool
 123 check_snat(struct fw3_state *state, struct fw3_snat *snat, struct uci_element *e)
 124 {
 125         if (!snat->enabled)
 126                 return false;
 127
 128         if (snat->src.invert)
 129         {
 130                 warn_section("nat", snat, e, "must not have an inverted source");
 131                 return false;
 132         }
 133         else if (snat->src.set && !snat->src.any &&
 134                         !(snat->_src = fw3_lookup_zone(state, snat->src.name)))
 135         {
 136                 warn_section("nat", snat, e, "refers to not existing zone '%s'", snat->src.name);
 137                 return false;
 138         }
 139         else if (snat->ipset.set && state->disable_ipsets)
 140         {
 141                 warn_section("nat", snat, e, "skipped due to disabled ipset support");
 142                 return false;
 143         }
 144         else if (snat->ipset.set &&
 145                         !(snat->ipset.ptr = fw3_lookup_ipset(state, snat->ipset.name)))
 146         {
 147                 warn_section("nat", snat, e, "refers to unknown ipset '%s'", snat->ipset.name);
 148                 return false;
 149         }
 150
 151         if (!check_families(e, snat))
 152                 return false;
 153
 154         if (snat->target == FW3_FLAG_UNSPEC)
 155         {
 156                 warn_section("nat", snat, e, "has no target specified, defaulting to MASQUERADE");
 157                 snat->target = FW3_FLAG_MASQUERADE;
 158         }
 159         else if (snat->target != FW3_FLAG_ACCEPT && snat->target != FW3_FLAG_SNAT &&
 160                         snat->target != FW3_FLAG_MASQUERADE)
 161         {
 162                 warn_section("nat", snat, e, "has invalid target specified, defaulting to MASQUERADE");
 163                 snat->target = FW3_FLAG_MASQUERADE;
 164         }
 165
 166         if (snat->target == FW3_FLAG_SNAT &&
 167                         !snat->ip_snat.set && !snat->port_snat.set)
 168         {
 169                 warn_section("nat", snat, e, "needs either 'snat_ip' or 'snat_port' for SNAT");
 170                 return false;
 171         }
 172         else if (snat->target != FW3_FLAG_SNAT && snat->ip_snat.set)
 173         {
 174                 warn_section("nat", snat, e, "must not use 'snat_ip' for non-SNAT");
 175                 return false;
 176         }
 177         else if (snat->target != FW3_FLAG_SNAT && snat->port_snat.set)
 178         {
 179                 warn_section("nat", snat, e, "must not use 'snat_port' for non-SNAT");
 180                 return false;
 181         }
 182
 183         if (list_empty(&snat->proto))
 184         {
 185                 warn_section("nat", snat, e, "does not specify a protocol, assuming all");
 186                 fw3_parse_protocol(&snat->proto, "all", true);
 187         }
 188
 189         if (snat->_src)
 190                 set(snat->_src->flags, FW3_FAMILY_V4, FW3_FLAG_SNAT);
 191
 192         return true;
 193 }
 194
 195
 196 void
 197 fw3_load_snats(struct fw3_state *state, struct uci_package *p, struct blob_attr *a)
 198 {
 199         struct uci_section *s;
 200         struct uci_element *e;
 201         struct fw3_snat *snat;
 202         struct blob_attr *entry;
 203         unsigned rem;
 204
 205         INIT_LIST_HEAD(&state->snats);
 206
 207         blob_for_each_attr(entry, a, rem) {
 208                 const char *type = NULL;
 209                 const char *name = "ubus rule";
 210
 211                 if (!fw3_attr_parse_name_type(entry, &name, &type))
 212                         continue;
 213
 214                 if (strcmp(type, "nat"))
 215                         continue;
 216
 217                 snat = alloc_snat(state);
 218                 if (!snat)
 219                         continue;
 220
 221                 if (!fw3_parse_blob_options(snat, fw3_snat_opts, entry, name))
 222                 {
 223                         warn_section("nat", snat, NULL, "skipped due to invalid options");
 224                         fw3_free_snat(snat);
 225                         continue;
 226                 }
 227
 228                 if (!check_snat(state, snat, NULL))
 229                         fw3_free_snat(snat);
 230         }
 231
 232         uci_foreach_element(&p->sections, e)
 233         {
 234                 s = uci_to_section(e);
 235
 236                 if (strcmp(s->type, "nat"))
 237                         continue;
 238
 239                 snat = alloc_snat(state);
 240                 if (!snat)
 241                         continue;
 242
 243                 if (!fw3_parse_options(snat, fw3_snat_opts, s))
 244                 {
 245                         warn_elem(e, "skipped due to invalid options");
 246                         fw3_free_snat(snat);
 247                         continue;
 248                 }
 249
 250                 if (!check_snat(state, snat, e))
 251                         fw3_free_snat(snat);
 252         }
 253 }
 254
 255 static void
 256 append_chain(struct fw3_ipt_rule *r, struct fw3_snat *snat)
 257 {
 258         if (snat->_src)
 259                 fw3_ipt_rule_append(r, "zone_%s_postrouting", snat->src.name);
 260         else
 261                 fw3_ipt_rule_append(r, "POSTROUTING");
 262 }
 263
 264 static void
 265 set_target(struct fw3_ipt_rule *r, struct fw3_snat *snat,
 266            struct fw3_protocol *proto)
 267 {
 268         char buf[sizeof("255.255.255.255:65535-65535")] = {};
 269         char ip[INET_ADDRSTRLEN], portcntbuf[6], *p = buf;
 270         size_t rem = sizeof(buf);
 271         int len;
 272
 273         if (snat->target == FW3_FLAG_SNAT)
 274         {
 275                 if (snat->ip_snat.set)
 276                 {
 277                         inet_ntop(AF_INET, &snat->ip_snat.address.v4, ip, sizeof(ip));
 278
 279                         len = snprintf(p, rem, "%s", ip);
 280
 281                         if (len < 0 || len >= rem)
 282                                 return;
 283
 284                         rem -= len;
 285                         p += len;
 286                 }
 287
 288                 if (snat->port_snat.set && proto && !proto->any &&
 289                     (proto->protocol == 6 || proto->protocol == 17 || proto->protocol == 1))
 290                 {
 291                         if (snat->port_snat.port_min == snat->port_snat.port_max)
 292                                 snprintf(p, rem, ":%u", snat->port_snat.port_min);
 293                         else
 294                                 snprintf(p, rem, ":%u-%u",
 295                                                  snat->port_snat.port_min, snat->port_snat.port_max);
 296
 297                         if (snat->connlimit_ports) {
 298                                 snprintf(portcntbuf, sizeof(portcntbuf), "%u",
 299                                          1 + snat->port_snat.port_max - snat->port_snat.port_min);
 300
 301                                 fw3_ipt_rule_addarg(r, false, "-m", "connlimit");
 302                                 fw3_ipt_rule_addarg(r, false, "--connlimit-daddr", NULL);
 303                                 fw3_ipt_rule_addarg(r, false, "--connlimit-upto", portcntbuf);
 304                         }
 305                 }
 306
 307                 fw3_ipt_rule_target(r, "SNAT");
 308                 fw3_ipt_rule_addarg(r, false, "--to-source", buf);
 309         }
 310         else if (snat->target == FW3_FLAG_ACCEPT)
 311         {
 312                 fw3_ipt_rule_target(r, "ACCEPT");
 313         }
 314         else
 315         {
 316                 fw3_ipt_rule_target(r, "MASQUERADE");
 317         }
 318 }
 319
 320 static void
 321 set_comment(struct fw3_ipt_rule *r, const char *name, int num)
 322 {
 323         if (name)
 324                 fw3_ipt_rule_comment(r, name);
 325         else
 326                 fw3_ipt_rule_comment(r, "@nat[%u]", num);
 327 }
 328
 329 static void
 330 print_snat(struct fw3_ipt_handle *h, struct fw3_state *state,
 331            struct fw3_snat *snat, int num, struct fw3_protocol *proto)
 332 {
 333         struct fw3_ipt_rule *r;
 334         struct fw3_address *src, *dst;
 335         struct fw3_port *spt, *dpt;
 336
 337         switch (h->table)
 338         {
 339         case FW3_TABLE_NAT:
 340                 src = &snat->ip_src;
 341                 dst = &snat->ip_dest;
 342                 spt = &snat->port_src;
 343                 dpt = &snat->port_dest;
 344
 345                 r = fw3_ipt_rule_create(h, proto, NULL, NULL, src, dst);
 346                 fw3_ipt_rule_sport_dport(r, spt, dpt);
 347                 fw3_ipt_rule_device(r, snat->device, true);
 348                 fw3_ipt_rule_ipset(r, &snat->ipset);
 349                 fw3_ipt_rule_limit(r, &snat->limit);
 350                 fw3_ipt_rule_time(r, &snat->time);
 351                 fw3_ipt_rule_mark(r, &snat->mark);
 352                 set_target(r, snat, proto);
 353                 fw3_ipt_rule_extra(r, snat->extra);
 354                 set_comment(r, snat->name, num);
 355                 append_chain(r, snat);
 356                 break;
 357
 358         default:
 359                 break;
 360         }
 361 }
 362
 363 static void
 364 expand_snat(struct fw3_ipt_handle *handle, struct fw3_state *state,
 365                 struct fw3_snat *snat, int num)
 366 {
 367         struct fw3_protocol *proto;
 368
 369         if (snat->name)
 370                 info("   * NAT '%s'", snat->name);
 371         else
 372                 info("   * NAT #%u", num);
 373
 374         if (!fw3_is_family(snat->_src, handle->family))
 375         {
 376                 info("     ! Skipping due to different family of zone");
 377                 return;
 378         }
 379
 380         if (!fw3_is_family(&snat->ip_src, handle->family) ||
 381             !fw3_is_family(&snat->ip_dest, handle->family) ||
 382                 !fw3_is_family(&snat->ip_snat, handle->family))
 383         {
 384                 if (!snat->ip_src.resolved ||
 385                     !snat->ip_dest.resolved ||
 386                     !snat->ip_snat.resolved)
 387                         info("     ! Skipping due to different family of ip address");
 388
 389                 return;
 390         }
 391
 392         if (snat->ipset.ptr)
 393         {
 394                 if (!fw3_is_family(snat->ipset.ptr, handle->family))
 395                 {
 396                         info("     ! Skipping due to different family in ipset");
 397                         return;
 398                 }
 399
 400                 if (!fw3_check_ipset(snat->ipset.ptr))
 401                 {
 402                         info("     ! Skipping due to missing ipset '%s'",
 403                              snat->ipset.ptr->external ?
 404                                         snat->ipset.ptr->external : snat->ipset.ptr->name);
 405                         return;
 406                 }
 407
 408                 set(snat->ipset.ptr->flags, handle->family, handle->family);
 409         }
 410
 411         fw3_foreach(proto, &snat->proto)
 412                 print_snat(handle, state, snat, num, proto);
 413 }
 414
 415 void
 416 fw3_print_snats(struct fw3_ipt_handle *handle, struct fw3_state *state)
 417 {
 418         int num = 0;
 419         struct fw3_snat *snat;
 420
 421         if (handle->family == FW3_FAMILY_V6)
 422                 return;
 423
 424         if (handle->table != FW3_TABLE_NAT)
 425                 return;
 426
 427         list_for_each_entry(snat, &state->snats, list)
 428                 expand_snat(handle, state, snat, num++);
 429 }