snats.c

   1 /*
   2  * firewall3 - 3rd OpenWrt UCI firewall implementation
   3  *
   4  *   Copyright (C) 2014 Jo-Philipp Wich <jow@openwrt.org>
   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_elem(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_elem(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_elem(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_elem(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_elem(e, "uses snat ip with different family");
 101                 return false;
 102         }
 103
 104         return true;
 105 }
 106
 107 void
 108 fw3_load_snats(struct fw3_state *state, struct uci_package *p)
 109 {
 110         struct uci_section *s;
 111         struct uci_element *e;
 112         struct fw3_snat *snat;
 113
 114         INIT_LIST_HEAD(&state->snats);
 115
 116         uci_foreach_element(&p->sections, e)
 117         {
 118                 s = uci_to_section(e);
 119
 120                 if (strcmp(s->type, "nat"))
 121                         continue;
 122
 123                 snat = malloc(sizeof(*snat));
 124
 125                 if (!snat)
 126                         continue;
 127
 128                 memset(snat, 0, sizeof(*snat));
 129
 130                 INIT_LIST_HEAD(&snat->proto);
 131
 132                 snat->enabled = true;
 133
 134                 if (!fw3_parse_options(snat, fw3_snat_opts, s))
 135                 {
 136                         warn_elem(e, "skipped due to invalid options");
 137                         fw3_free_snat(snat);
 138                         continue;
 139                 }
 140
 141                 if (!snat->enabled)
 142                 {
 143                         fw3_free_snat(snat);
 144                         continue;
 145                 }
 146
 147                 if (snat->src.invert)
 148                 {
 149                         warn_elem(e, "must not have an inverted source");
 150                         fw3_free_snat(snat);
 151                         continue;
 152                 }
 153                 else if (snat->src.set && !snat->src.any &&
 154                          !(snat->_src = fw3_lookup_zone(state, snat->src.name)))
 155                 {
 156                         warn_elem(e, "refers to not existing zone '%s'", snat->src.name);
 157                         fw3_free_snat(snat);
 158                         continue;
 159                 }
 160                 else if (snat->ipset.set && state->disable_ipsets)
 161                 {
 162                         warn_elem(e, "skipped due to disabled ipset support");
 163                         fw3_free_snat(snat);
 164                         continue;
 165                 }
 166                 else if (snat->ipset.set &&
 167                          !(snat->ipset.ptr = fw3_lookup_ipset(state, snat->ipset.name)))
 168                 {
 169                         warn_elem(e, "refers to unknown ipset '%s'", snat->ipset.name);
 170                         fw3_free_snat(snat);
 171                         continue;
 172                 }
 173
 174                 if (!check_families(e, snat))
 175                 {
 176                         fw3_free_snat(snat);
 177                         continue;
 178                 }
 179
 180                 if (snat->target == FW3_FLAG_UNSPEC)
 181                 {
 182                         warn_elem(e, "has no target specified, defaulting to MASQUERADE");
 183                         snat->target = FW3_FLAG_MASQUERADE;
 184                 }
 185                 else if (snat->target != FW3_FLAG_ACCEPT && snat->target != FW3_FLAG_SNAT &&
 186                                 snat->target != FW3_FLAG_MASQUERADE)
 187                 {
 188                         warn_elem(e, "has invalid target specified, defaulting to MASQUERADE");
 189                         snat->target = FW3_FLAG_MASQUERADE;
 190                 }
 191
 192                 if (snat->target == FW3_FLAG_SNAT &&
 193                     !snat->ip_snat.set && !snat->port_snat.set)
 194                 {
 195                         warn_elem(e, "needs either 'snat_ip' or 'snat_port' for SNAT");
 196                         fw3_free_snat(snat);
 197                         continue;
 198                 }
 199                 else if (snat->target != FW3_FLAG_SNAT && snat->ip_snat.set)
 200                 {
 201                         warn_elem(e, "must not use 'snat_ip' for non-SNAT");
 202                         fw3_free_snat(snat);
 203                         continue;
 204                 }
 205                 else if (snat->target != FW3_FLAG_SNAT && snat->port_snat.set)
 206                 {
 207                         warn_elem(e, "must not use 'snat_port' for non-SNAT");
 208                         fw3_free_snat(snat);
 209                         continue;
 210                 }
 211
 212                 if (list_empty(&snat->proto))
 213                 {
 214                         warn_elem(e, "does not specify a protocol, assuming all");
 215                         fw3_parse_protocol(&snat->proto, "all", true);
 216                 }
 217
 218                 if (snat->_src)
 219                 {
 220                         set(snat->_src->flags, FW3_FAMILY_V4, FW3_FLAG_SNAT);
 221                         snat->_src->conntrack = true;
 222                 }
 223
 224                 list_add_tail(&snat->list, &state->snats);
 225         }
 226 }
 227
 228 static void
 229 append_chain(struct fw3_ipt_rule *r, struct fw3_snat *snat)
 230 {
 231         if (snat->_src)
 232                 fw3_ipt_rule_append(r, "zone_%s_postrouting", snat->src.name);
 233         else
 234                 fw3_ipt_rule_append(r, "delegate_postrouting");
 235 }
 236
 237 static void
 238 set_target(struct fw3_ipt_rule *r, struct fw3_snat *snat,
 239            struct fw3_protocol *proto)
 240 {
 241         char buf[sizeof("255.255.255.255:65535-65535\0")];
 242
 243         if (snat->target == FW3_FLAG_SNAT)
 244         {
 245                 buf[0] = '\0';
 246
 247                 if (snat->ip_snat.set)
 248                 {
 249                         inet_ntop(AF_INET, &snat->ip_snat.address.v4, buf, sizeof(buf));
 250                 }
 251
 252                 if (snat->port_snat.set && proto && !proto->any &&
 253                     (proto->protocol == 6 || proto->protocol == 17 || proto->protocol == 1))
 254                 {
 255                         if (snat->port_snat.port_min == snat->port_snat.port_max)
 256                                 sprintf(buf + strlen(buf), ":%u", snat->port_snat.port_min);
 257                         else
 258                                 sprintf(buf + strlen(buf), ":%u-%u",
 259                                                 snat->port_snat.port_min, snat->port_snat.port_max);
 260
 261                         if (snat->connlimit_ports) {
 262                                 char portcntbuf[6];
 263                                 snprintf(portcntbuf, sizeof(portcntbuf), "%u",
 264                                                 1 + snat->port_snat.port_max - snat->port_snat.port_min);
 265
 266                                 fw3_ipt_rule_addarg(r, false, "-m", "connlimit");
 267                                 fw3_ipt_rule_addarg(r, false, "--connlimit-daddr", NULL);
 268                                 fw3_ipt_rule_addarg(r, false, "--connlimit-upto", portcntbuf);
 269                         }
 270                 }
 271
 272                 fw3_ipt_rule_target(r, "SNAT");
 273                 fw3_ipt_rule_addarg(r, false, "--to-source", buf);
 274         }
 275         else if (snat->target == FW3_FLAG_ACCEPT)
 276         {
 277                 fw3_ipt_rule_target(r, "ACCEPT");
 278         }
 279         else
 280         {
 281                 fw3_ipt_rule_target(r, "MASQUERADE");
 282         }
 283 }
 284
 285 static void
 286 set_comment(struct fw3_ipt_rule *r, const char *name, int num)
 287 {
 288         if (name)
 289                 fw3_ipt_rule_comment(r, name);
 290         else
 291                 fw3_ipt_rule_comment(r, "@nat[%u]", num);
 292 }
 293
 294 static void
 295 print_snat(struct fw3_ipt_handle *h, struct fw3_state *state,
 296            struct fw3_snat *snat, int num, struct fw3_protocol *proto)
 297 {
 298         struct fw3_ipt_rule *r;
 299         struct fw3_address *src, *dst;
 300         struct fw3_port *spt, *dpt;
 301
 302         switch (h->table)
 303         {
 304         case FW3_TABLE_NAT:
 305                 src = &snat->ip_src;
 306                 dst = &snat->ip_dest;
 307                 spt = &snat->port_src;
 308                 dpt = &snat->port_dest;
 309
 310                 r = fw3_ipt_rule_create(h, proto, NULL, NULL, src, dst);
 311                 fw3_ipt_rule_sport_dport(r, spt, dpt);
 312                 fw3_ipt_rule_device(r, snat->device, true);
 313                 fw3_ipt_rule_ipset(r, &snat->ipset);
 314                 fw3_ipt_rule_limit(r, &snat->limit);
 315                 fw3_ipt_rule_time(r, &snat->time);
 316                 fw3_ipt_rule_mark(r, &snat->mark);
 317                 set_target(r, snat, proto);
 318                 fw3_ipt_rule_extra(r, snat->extra);
 319                 set_comment(r, snat->name, num);
 320                 append_chain(r, snat);
 321                 break;
 322
 323         default:
 324                 break;
 325         }
 326 }
 327
 328 static void
 329 expand_snat(struct fw3_ipt_handle *handle, struct fw3_state *state,
 330                 struct fw3_snat *snat, int num)
 331 {
 332         struct fw3_protocol *proto;
 333
 334         if (snat->name)
 335                 info("   * NAT '%s'", snat->name);
 336         else
 337                 info("   * NAT #%u", num);
 338
 339         if (!fw3_is_family(snat->_src, handle->family))
 340         {
 341                 info("     ! Skipping due to different family of zone");
 342                 return;
 343         }
 344
 345         if (!fw3_is_family(&snat->ip_src, handle->family) ||
 346             !fw3_is_family(&snat->ip_dest, handle->family) ||
 347                 !fw3_is_family(&snat->ip_snat, handle->family))
 348         {
 349                 if (!snat->ip_src.resolved ||
 350                     !snat->ip_dest.resolved ||
 351                     !snat->ip_snat.resolved)
 352                         info("     ! Skipping due to different family of ip address");
 353
 354                 return;
 355         }
 356
 357         if (snat->ipset.ptr)
 358         {
 359                 if (!fw3_is_family(snat->ipset.ptr, handle->family))
 360                 {
 361                         info("     ! Skipping due to different family in ipset");
 362                         return;
 363                 }
 364
 365                 if (!fw3_check_ipset(snat->ipset.ptr))
 366                 {
 367                         info("     ! Skipping due to missing ipset '%s'",
 368                              snat->ipset.ptr->external ?
 369                                         snat->ipset.ptr->external : snat->ipset.ptr->name);
 370                         return;
 371                 }
 372
 373                 set(snat->ipset.ptr->flags, handle->family, handle->family);
 374         }
 375
 376         fw3_foreach(proto, &snat->proto)
 377                 print_snat(handle, state, snat, num, proto);
 378 }
 379
 380 void
 381 fw3_print_snats(struct fw3_ipt_handle *handle, struct fw3_state *state)
 382 {
 383         int num = 0;
 384         struct fw3_snat *snat;
 385
 386         if (handle->family == FW3_FAMILY_V6)
 387                 return;
 388
 389         if (handle->table != FW3_TABLE_NAT)
 390                 return;
 391
 392         list_for_each_entry(snat, &state->snats, list)
 393                 expand_snat(handle, state, snat, num++);
 394 }