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_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
 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
 123 void
 124 fw3_load_snats(struct fw3_state *state, struct uci_package *p, struct blob_attr *a)
 125 {
 126         struct uci_section *s;
 127         struct uci_element *e;
 128         struct fw3_snat *snat, *n;
 129         struct blob_attr *entry, *opt;
 130         unsigned rem, orem;
 131
 132         INIT_LIST_HEAD(&state->snats);
 133
 134         blob_for_each_attr(entry, a, rem) {
 135                 const char *type = NULL;
 136                 const char *name = "ubus rule";
 137
 138                 if (!fw3_attr_parse_name_type(entry, &name, &type))
 139                         continue;
 140
 141                 if (strcmp(type, "nat"))
 142                         continue;
 143
 144                 if (!(snat = alloc_snat(state)))
 145                         continue;
 146
 147                 if (!fw3_parse_blob_options(snat, fw3_snat_opts, rule, name))
 148                 {
 149                         warn_section("nat", snat, NULL, "skipped due to invalid options");
 150                         fw3_free_snat(snat);
 151                         continue;
 152                 }
 153         }
 154
 155         uci_foreach_element(&p->sections, e)
 156         {
 157                 s = uci_to_section(e);
 158
 159                 if (strcmp(s->type, "nat"))
 160                         continue;
 161
 162                 if (!(snat = alloc_snat(state)))
 163                         continue;
 164
 165                 if (!fw3_parse_options(snat, fw3_snat_opts, s))
 166                 {
 167                         warn_elem(e, "skipped due to invalid options");
 168                         fw3_free_snat(snat);
 169                         continue;
 170                 }
 171         }
 172
 173         list_for_each_entry_safe(snat, n, &state->snats, list)
 174         {
 175                 if (!snat->enabled)
 176                 {
 177                         fw3_free_snat(snat);
 178                         continue;
 179                 }
 180
 181                 if (snat->src.invert)
 182                 {
 183                         warn_elem(e, "must not have an inverted source");
 184                         fw3_free_snat(snat);
 185                         continue;
 186                 }
 187                 else if (snat->src.set && !snat->src.any &&
 188                          !(snat->_src = fw3_lookup_zone(state, snat->src.name)))
 189                 {
 190                         warn_elem(e, "refers to not existing zone '%s'", snat->src.name);
 191                         fw3_free_snat(snat);
 192                         continue;
 193                 }
 194                 else if (snat->ipset.set && state->disable_ipsets)
 195                 {
 196                         warn_elem(e, "skipped due to disabled ipset support");
 197                         fw3_free_snat(snat);
 198                         continue;
 199                 }
 200                 else if (snat->ipset.set &&
 201                          !(snat->ipset.ptr = fw3_lookup_ipset(state, snat->ipset.name)))
 202                 {
 203                         warn_elem(e, "refers to unknown ipset '%s'", snat->ipset.name);
 204                         fw3_free_snat(snat);
 205                         continue;
 206                 }
 207
 208                 if (!check_families(e, snat))
 209                 {
 210                         fw3_free_snat(snat);
 211                         continue;
 212                 }
 213
 214                 if (snat->target == FW3_FLAG_UNSPEC)
 215                 {
 216                         warn_elem(e, "has no target specified, defaulting to MASQUERADE");
 217                         snat->target = FW3_FLAG_MASQUERADE;
 218                 }
 219                 else if (snat->target != FW3_FLAG_ACCEPT && snat->target != FW3_FLAG_SNAT &&
 220                                 snat->target != FW3_FLAG_MASQUERADE)
 221                 {
 222                         warn_elem(e, "has invalid target specified, defaulting to MASQUERADE");
 223                         snat->target = FW3_FLAG_MASQUERADE;
 224                 }
 225
 226                 if (snat->target == FW3_FLAG_SNAT &&
 227                     !snat->ip_snat.set && !snat->port_snat.set)
 228                 {
 229                         warn_elem(e, "needs either 'snat_ip' or 'snat_port' for SNAT");
 230                         fw3_free_snat(snat);
 231                         continue;
 232                 }
 233                 else if (snat->target != FW3_FLAG_SNAT && snat->ip_snat.set)
 234                 {
 235                         warn_elem(e, "must not use 'snat_ip' for non-SNAT");
 236                         fw3_free_snat(snat);
 237                         continue;
 238                 }
 239                 else if (snat->target != FW3_FLAG_SNAT && snat->port_snat.set)
 240                 {
 241                         warn_elem(e, "must not use 'snat_port' for non-SNAT");
 242                         fw3_free_snat(snat);
 243                         continue;
 244                 }
 245
 246                 if (list_empty(&snat->proto))
 247                 {
 248                         warn_elem(e, "does not specify a protocol, assuming all");
 249                         fw3_parse_protocol(&snat->proto, "all", true);
 250                 }
 251
 252                 if (snat->_src)
 253                         set(snat->_src->flags, FW3_FAMILY_V4, FW3_FLAG_SNAT);
 254         }
 255 }
 256
 257 static void
 258 append_chain(struct fw3_ipt_rule *r, struct fw3_snat *snat)
 259 {
 260         if (snat->_src)
 261                 fw3_ipt_rule_append(r, "zone_%s_postrouting", snat->src.name);
 262         else
 263                 fw3_ipt_rule_append(r, "POSTROUTING");
 264 }
 265
 266 static void
 267 set_target(struct fw3_ipt_rule *r, struct fw3_snat *snat,
 268            struct fw3_protocol *proto)
 269 {
 270         char buf[sizeof("255.255.255.255:65535-65535\0")];
 271
 272         if (snat->target == FW3_FLAG_SNAT)
 273         {
 274                 buf[0] = '\0';
 275
 276                 if (snat->ip_snat.set)
 277                 {
 278                         inet_ntop(AF_INET, &snat->ip_snat.address.v4, buf, sizeof(buf));
 279                 }
 280
 281                 if (snat->port_snat.set && proto && !proto->any &&
 282                     (proto->protocol == 6 || proto->protocol == 17 || proto->protocol == 1))
 283                 {
 284                         if (snat->port_snat.port_min == snat->port_snat.port_max)
 285                                 sprintf(buf + strlen(buf), ":%u", snat->port_snat.port_min);
 286                         else
 287                                 sprintf(buf + strlen(buf), ":%u-%u",
 288                                                 snat->port_snat.port_min, snat->port_snat.port_max);
 289
 290                         if (snat->connlimit_ports) {
 291                                 char portcntbuf[6];
 292                                 snprintf(portcntbuf, sizeof(portcntbuf), "%u",
 293                                                 1 + snat->port_snat.port_max - snat->port_snat.port_min);
 294
 295                                 fw3_ipt_rule_addarg(r, false, "-m", "connlimit");
 296                                 fw3_ipt_rule_addarg(r, false, "--connlimit-daddr", NULL);
 297                                 fw3_ipt_rule_addarg(r, false, "--connlimit-upto", portcntbuf);
 298                         }
 299                 }
 300
 301                 fw3_ipt_rule_target(r, "SNAT");
 302                 fw3_ipt_rule_addarg(r, false, "--to-source", buf);
 303         }
 304         else if (snat->target == FW3_FLAG_ACCEPT)
 305         {
 306                 fw3_ipt_rule_target(r, "ACCEPT");
 307         }
 308         else
 309         {
 310                 fw3_ipt_rule_target(r, "MASQUERADE");
 311         }
 312 }
 313
 314 static void
 315 set_comment(struct fw3_ipt_rule *r, const char *name, int num)
 316 {
 317         if (name)
 318                 fw3_ipt_rule_comment(r, name);
 319         else
 320                 fw3_ipt_rule_comment(r, "@nat[%u]", num);
 321 }
 322
 323 static void
 324 print_snat(struct fw3_ipt_handle *h, struct fw3_state *state,
 325            struct fw3_snat *snat, int num, struct fw3_protocol *proto)
 326 {
 327         struct fw3_ipt_rule *r;
 328         struct fw3_address *src, *dst;
 329         struct fw3_port *spt, *dpt;
 330
 331         switch (h->table)
 332         {
 333         case FW3_TABLE_NAT:
 334                 src = &snat->ip_src;
 335                 dst = &snat->ip_dest;
 336                 spt = &snat->port_src;
 337                 dpt = &snat->port_dest;
 338
 339                 r = fw3_ipt_rule_create(h, proto, NULL, NULL, src, dst);
 340                 fw3_ipt_rule_sport_dport(r, spt, dpt);
 341                 fw3_ipt_rule_device(r, snat->device, true);
 342                 fw3_ipt_rule_ipset(r, &snat->ipset);
 343                 fw3_ipt_rule_limit(r, &snat->limit);
 344                 fw3_ipt_rule_time(r, &snat->time);
 345                 fw3_ipt_rule_mark(r, &snat->mark);
 346                 set_target(r, snat, proto);
 347                 fw3_ipt_rule_extra(r, snat->extra);
 348                 set_comment(r, snat->name, num);
 349                 append_chain(r, snat);
 350                 break;
 351
 352         default:
 353                 break;
 354         }
 355 }
 356
 357 static void
 358 expand_snat(struct fw3_ipt_handle *handle, struct fw3_state *state,
 359                 struct fw3_snat *snat, int num)
 360 {
 361         struct fw3_protocol *proto;
 362
 363         if (snat->name)
 364                 info("   * NAT '%s'", snat->name);
 365         else
 366                 info("   * NAT #%u", num);
 367
 368         if (!fw3_is_family(snat->_src, handle->family))
 369         {
 370                 info("     ! Skipping due to different family of zone");
 371                 return;
 372         }
 373
 374         if (!fw3_is_family(&snat->ip_src, handle->family) ||
 375             !fw3_is_family(&snat->ip_dest, handle->family) ||
 376                 !fw3_is_family(&snat->ip_snat, handle->family))
 377         {
 378                 if (!snat->ip_src.resolved ||
 379                     !snat->ip_dest.resolved ||
 380                     !snat->ip_snat.resolved)
 381                         info("     ! Skipping due to different family of ip address");
 382
 383                 return;
 384         }
 385
 386         if (snat->ipset.ptr)
 387         {
 388                 if (!fw3_is_family(snat->ipset.ptr, handle->family))
 389                 {
 390                         info("     ! Skipping due to different family in ipset");
 391                         return;
 392                 }
 393
 394                 if (!fw3_check_ipset(snat->ipset.ptr))
 395                 {
 396                         info("     ! Skipping due to missing ipset '%s'",
 397                              snat->ipset.ptr->external ?
 398                                         snat->ipset.ptr->external : snat->ipset.ptr->name);
 399                         return;
 400                 }
 401
 402                 set(snat->ipset.ptr->flags, handle->family, handle->family);
 403         }
 404
 405         fw3_foreach(proto, &snat->proto)
 406                 print_snat(handle, state, snat, num, proto);
 407 }
 408
 409 void
 410 fw3_print_snats(struct fw3_ipt_handle *handle, struct fw3_state *state)
 411 {
 412         int num = 0;
 413         struct fw3_snat *snat;
 414
 415         if (handle->family == FW3_FAMILY_V6)
 416                 return;
 417
 418         if (handle->table != FW3_TABLE_NAT)
 419                 return;
 420
 421         list_for_each_entry(snat, &state->snats, list)
 422                 expand_snat(handle, state, snat, num++);
 423 }