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
  30         FW3_OPT("ipset",               setmatch,  snat,     ipset),
  31
  32         FW3_LIST("proto",              protocol,  snat,     proto),
  33
  34         FW3_OPT("src_ip",              network,   snat,     ip_src),
  35         FW3_OPT("src_port",            port,      snat,     port_src),
  36
  37         FW3_OPT("snat_ip",             network,   snat,     ip_snat),
  38         FW3_OPT("snat_port",           port,      snat,     port_snat),
  39
  40         FW3_OPT("dest_ip",             network,   snat,     ip_dest),
  41         FW3_OPT("dest_port",           port,      snat,     port_dest),
  42
  43         FW3_OPT("extra",               string,    snat,     extra),
  44
  45         FW3_OPT("limit",               limit,     snat,     limit),
  46         FW3_OPT("limit_burst",         int,       snat,     limit.burst),
  47
  48         FW3_OPT("utc_time",            bool,      snat,     time.utc),
  49         FW3_OPT("start_date",          date,      snat,     time.datestart),
  50         FW3_OPT("stop_date",           date,      snat,     time.datestop),
  51         FW3_OPT("start_time",          time,      snat,     time.timestart),
  52         FW3_OPT("stop_time",           time,      snat,     time.timestop),
  53         FW3_OPT("weekdays",            weekdays,  snat,     time.weekdays),
  54         FW3_OPT("monthdays",           monthdays, snat,     time.monthdays),
  55
  56         FW3_OPT("mark",                mark,      snat,     mark),
  57
  58         FW3_OPT("target",              target,    snat,     target),
  59
  60         { }
  61 };
  62
  63
  64 static bool
  65 check_families(struct uci_element *e, struct fw3_snat *r)
  66 {
  67         if (r->family == FW3_FAMILY_ANY)
  68                 return true;
  69
  70         if (r->_src && r->_src->family && r->_src->family != r->family)
  71         {
  72                 warn_elem(e, "refers to source zone with different family");
  73                 return false;
  74         }
  75
  76         if (r->ipset.ptr && r->ipset.ptr->family &&
  77             r->ipset.ptr->family != r->family)
  78         {
  79                 warn_elem(e, "refers to ipset with different family");
  80                 return false;
  81         }
  82
  83         if (r->ip_src.family && r->ip_src.family != r->family)
  84         {
  85                 warn_elem(e, "uses source ip with different family");
  86                 return false;
  87         }
  88
  89         if (r->ip_dest.family && r->ip_dest.family != r->family)
  90         {
  91                 warn_elem(e, "uses destination ip with different family");
  92                 return false;
  93         }
  94
  95         if (r->ip_snat.family && r->ip_snat.family != r->family)
  96         {
  97                 warn_elem(e, "uses snat ip with different family");
  98                 return false;
  99         }
 100
 101         return true;
 102 }
 103
 104 void
 105 fw3_load_snats(struct fw3_state *state, struct uci_package *p)
 106 {
 107         struct uci_section *s;
 108         struct uci_element *e;
 109         struct fw3_snat *snat;
 110
 111         INIT_LIST_HEAD(&state->snats);
 112
 113         uci_foreach_element(&p->sections, e)
 114         {
 115                 s = uci_to_section(e);
 116
 117                 if (strcmp(s->type, "nat"))
 118                         continue;
 119
 120                 snat = malloc(sizeof(*snat));
 121
 122                 if (!snat)
 123                         continue;
 124
 125                 memset(snat, 0, sizeof(*snat));
 126
 127                 INIT_LIST_HEAD(&snat->proto);
 128
 129                 snat->enabled = true;
 130
 131                 if (!fw3_parse_options(snat, fw3_snat_opts, s))
 132                 {
 133                         warn_elem(e, "skipped due to invalid options");
 134                         fw3_free_snat(snat);
 135                         continue;
 136                 }
 137
 138                 if (!snat->enabled)
 139                 {
 140                         fw3_free_snat(snat);
 141                         continue;
 142                 }
 143
 144                 if (snat->src.invert)
 145                 {
 146                         warn_elem(e, "must not have an inverted source");
 147                         fw3_free_snat(snat);
 148                         continue;
 149                 }
 150                 else if (snat->src.set && !snat->src.any &&
 151                          !(snat->_src = fw3_lookup_zone(state, snat->src.name)))
 152                 {
 153                         warn_elem(e, "refers to not existing zone '%s'", snat->src.name);
 154                         fw3_free_snat(snat);
 155                         continue;
 156                 }
 157                 else if (snat->ipset.set && state->disable_ipsets)
 158                 {
 159                         warn_elem(e, "skipped due to disabled ipset support");
 160                         fw3_free_snat(snat);
 161                         continue;
 162                 }
 163                 else if (snat->ipset.set &&
 164                          !(snat->ipset.ptr = fw3_lookup_ipset(state, snat->ipset.name)))
 165                 {
 166                         warn_elem(e, "refers to unknown ipset '%s'", snat->ipset.name);
 167                         fw3_free_snat(snat);
 168                         continue;
 169                 }
 170
 171                 if (!check_families(e, snat))
 172                 {
 173                         fw3_free_snat(snat);
 174                         continue;
 175                 }
 176
 177                 if (snat->target == FW3_FLAG_UNSPEC)
 178                 {
 179                         warn_elem(e, "has no target specified, defaulting to MASQUERADE");
 180                         snat->target = FW3_FLAG_MASQUERADE;
 181                 }
 182                 else if (snat->target < FW3_FLAG_SNAT || snat->target > FW3_FLAG_MASQUERADE)
 183                 {
 184                         warn_elem(e, "has invalid target specified, defaulting to MASQUERADE");
 185                         snat->target = FW3_FLAG_MASQUERADE;
 186                 }
 187
 188                 if (snat->target == FW3_FLAG_SNAT &&
 189                     !snat->ip_snat.set && !snat->port_snat.set)
 190                 {
 191                         warn_elem(e, "needs either 'snat_ip' or 'snat_port' for SNAT");
 192                         fw3_free_snat(snat);
 193                         continue;
 194                 }
 195                 else if (snat->target == FW3_FLAG_MASQUERADE && snat->ip_snat.set)
 196                 {
 197                         warn_elem(e, "must not use 'snat_ip' for MASQUERADE");
 198                         fw3_free_snat(snat);
 199                         continue;
 200                 }
 201                 else if (snat->target == FW3_FLAG_MASQUERADE && snat->port_snat.set)
 202                 {
 203                         warn_elem(e, "must not use 'snat_port' for MASQUERADE");
 204                         fw3_free_snat(snat);
 205                         continue;
 206                 }
 207
 208                 if (list_empty(&snat->proto))
 209                 {
 210                         warn_elem(e, "does not specify a protocol, assuming all");
 211                         fw3_parse_protocol(&snat->proto, "all", true);
 212                 }
 213
 214                 if (snat->_src)
 215                 {
 216                         set(snat->_src->flags, FW3_FAMILY_V4, FW3_FLAG_SNAT);
 217                         snat->_src->conntrack = true;
 218                 }
 219
 220                 list_add_tail(&snat->list, &state->snats);
 221         }
 222 }
 223
 224 static void
 225 append_chain(struct fw3_ipt_rule *r, struct fw3_snat *snat)
 226 {
 227         if (snat->_src)
 228                 fw3_ipt_rule_append(r, "zone_%s_postrouting", snat->src.name);
 229         else
 230                 fw3_ipt_rule_append(r, "delegate_postrouting");
 231 }
 232
 233 static void
 234 set_target(struct fw3_ipt_rule *r, struct fw3_snat *snat,
 235            struct fw3_protocol *proto)
 236 {
 237         char buf[sizeof("255.255.255.255:65535-65535\0")];
 238
 239         if (snat->target == FW3_FLAG_SNAT)
 240         {
 241                 buf[0] = '\0';
 242
 243                 if (snat->ip_snat.set)
 244                 {
 245                         inet_ntop(AF_INET, &snat->ip_snat.address.v4, buf, sizeof(buf));
 246                 }
 247
 248                 if (snat->port_snat.set && proto && !proto->any &&
 249                     (proto->protocol == 6 || proto->protocol == 17))
 250                 {
 251                         if (snat->port_snat.port_min == snat->port_snat.port_max)
 252                                 sprintf(buf + strlen(buf), ":%u", snat->port_snat.port_min);
 253                         else
 254                                 sprintf(buf + strlen(buf), ":%u-%u",
 255                                                 snat->port_snat.port_min, snat->port_snat.port_max);
 256                 }
 257
 258                 fw3_ipt_rule_target(r, "SNAT");
 259                 fw3_ipt_rule_addarg(r, false, "--to-source", buf);
 260         }
 261         else
 262         {
 263                 fw3_ipt_rule_target(r, "MASQUERADE");
 264         }
 265 }
 266
 267 static void
 268 set_comment(struct fw3_ipt_rule *r, const char *name, int num)
 269 {
 270         if (name)
 271                 fw3_ipt_rule_comment(r, name);
 272         else
 273                 fw3_ipt_rule_comment(r, "@nat[%u]", num);
 274 }
 275
 276 static void
 277 print_snat(struct fw3_ipt_handle *h, struct fw3_state *state,
 278            struct fw3_snat *snat, int num, struct fw3_protocol *proto)
 279 {
 280         struct fw3_ipt_rule *r;
 281         struct fw3_address *src, *dst;
 282         struct fw3_port *spt, *dpt;
 283
 284         switch (h->table)
 285         {
 286         case FW3_TABLE_NAT:
 287                 src = &snat->ip_src;
 288                 dst = &snat->ip_dest;
 289                 spt = &snat->port_src;
 290                 dpt = &snat->port_dest;
 291
 292                 r = fw3_ipt_rule_create(h, proto, NULL, NULL, src, dst);
 293                 fw3_ipt_rule_sport_dport(r, spt, dpt);
 294                 fw3_ipt_rule_ipset(r, &snat->ipset);
 295                 fw3_ipt_rule_limit(r, &snat->limit);
 296                 fw3_ipt_rule_time(r, &snat->time);
 297                 fw3_ipt_rule_mark(r, &snat->mark);
 298                 set_target(r, snat, proto);
 299                 fw3_ipt_rule_extra(r, snat->extra);
 300                 set_comment(r, snat->name, num);
 301                 append_chain(r, snat);
 302                 break;
 303
 304         default:
 305                 break;
 306         }
 307 }
 308
 309 static void
 310 expand_snat(struct fw3_ipt_handle *handle, struct fw3_state *state,
 311                 struct fw3_snat *snat, int num)
 312 {
 313         struct fw3_protocol *proto;
 314
 315         if (snat->name)
 316                 info("   * NAT '%s'", snat->name);
 317         else
 318                 info("   * NAT #%u", num);
 319
 320         if (!fw3_is_family(snat->_src, handle->family))
 321         {
 322                 info("     ! Skipping due to different family of zone");
 323                 return;
 324         }
 325
 326         if (!fw3_is_family(&snat->ip_src, handle->family) ||
 327             !fw3_is_family(&snat->ip_dest, handle->family) ||
 328                 !fw3_is_family(&snat->ip_snat, handle->family))
 329         {
 330                 if (!snat->ip_src.resolved ||
 331                     !snat->ip_dest.resolved ||
 332                     !snat->ip_snat.resolved)
 333                         info("     ! Skipping due to different family of ip address");
 334
 335                 return;
 336         }
 337
 338         if (snat->ipset.ptr)
 339         {
 340                 if (!fw3_is_family(snat->ipset.ptr, handle->family))
 341                 {
 342                         info("     ! Skipping due to different family in ipset");
 343                         return;
 344                 }
 345
 346                 if (!fw3_check_ipset(snat->ipset.ptr))
 347                 {
 348                         info("     ! Skipping due to missing ipset '%s'",
 349                              snat->ipset.ptr->external ?
 350                                         snat->ipset.ptr->external : snat->ipset.ptr->name);
 351                         return;
 352                 }
 353
 354                 set(snat->ipset.ptr->flags, handle->family, handle->family);
 355         }
 356
 357         fw3_foreach(proto, &snat->proto)
 358                 print_snat(handle, state, snat, num, proto);
 359 }
 360
 361 void
 362 fw3_print_snats(struct fw3_ipt_handle *handle, struct fw3_state *state)
 363 {
 364         int num = 0;
 365         struct fw3_snat *snat;
 366
 367         if (handle->family == FW3_FAMILY_V6)
 368                 return;
 369
 370         if (handle->table != FW3_TABLE_NAT)
 371                 return;
 372
 373         list_for_each_entry(snat, &state->snats, list)
 374                 expand_snat(handle, state, snat, num++);
 375 }