redirects.c

   1 /*
   2  * firewall3 - 3rd OpenWrt UCI firewall implementation
   3  *
   4  *   Copyright (C) 2013 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 "redirects.h"
  20
  21
  22 const struct fw3_option fw3_redirect_opts[] = {
  23         FW3_OPT("enabled",             bool,      redirect,     enabled),
  24
  25         FW3_OPT("name",                string,    redirect,     name),
  26         FW3_OPT("family",              family,    redirect,     family),
  27
  28         FW3_OPT("src",                 device,    redirect,     src),
  29         FW3_OPT("dest",                device,    redirect,     dest),
  30
  31         FW3_OPT("ipset",               device,    redirect,     ipset),
  32
  33         FW3_LIST("proto",              protocol,  redirect,     proto),
  34
  35         FW3_OPT("src_ip",              network,   redirect,     ip_src),
  36         FW3_LIST("src_mac",            mac,       redirect,     mac_src),
  37         FW3_OPT("src_port",            port,      redirect,     port_src),
  38
  39         FW3_OPT("src_dip",             network,   redirect,     ip_dest),
  40         FW3_OPT("src_dport",           port,      redirect,     port_dest),
  41
  42         FW3_OPT("dest_ip",             network,   redirect,     ip_redir),
  43         FW3_OPT("dest_port",           port,      redirect,     port_redir),
  44
  45         FW3_OPT("extra",               string,    redirect,     extra),
  46
  47         FW3_OPT("utc_time",            bool,      redirect,     time.utc),
  48         FW3_OPT("start_date",          date,      redirect,     time.datestart),
  49         FW3_OPT("stop_date",           date,      redirect,     time.datestop),
  50         FW3_OPT("start_time",          time,      redirect,     time.timestart),
  51         FW3_OPT("stop_time",           time,      redirect,     time.timestop),
  52         FW3_OPT("weekdays",            weekdays,  redirect,     time.weekdays),
  53         FW3_OPT("monthdays",           monthdays, redirect,     time.monthdays),
  54
  55         FW3_OPT("mark",                mark,      redirect,     mark),
  56
  57         FW3_OPT("reflection",          bool,      redirect,     reflection),
  58         FW3_OPT("reflection_src",      reflection_source,
  59                                                   redirect,     reflection_src),
  60
  61         FW3_OPT("target",              target,    redirect,     target),
  62
  63         { }
  64 };
  65
  66
  67 static bool
  68 check_families(struct uci_element *e, struct fw3_redirect *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->_dest && r->_dest->family && r->_dest->family != r->family)
  80         {
  81                 warn_elem(e, "refers to destination zone with different family");
  82                 return false;
  83         }
  84
  85         if (r->_ipset && r->_ipset->family && r->_ipset->family != r->family)
  86         {
  87                 warn_elem(e, "refers to ipset with different family");
  88                 return false;
  89         }
  90
  91         if (r->ip_src.family && r->ip_src.family != r->family)
  92         {
  93                 warn_elem(e, "uses source ip with different family");
  94                 return false;
  95         }
  96
  97         if (r->ip_dest.family && r->ip_dest.family != r->family)
  98         {
  99                 warn_elem(e, "uses destination ip with different family");
 100                 return false;
 101         }
 102
 103         if (r->ip_redir.family && r->ip_redir.family != r->family)
 104         {
 105                 warn_elem(e, "uses redirect ip with different family");
 106                 return false;
 107         }
 108
 109         return true;
 110 }
 111
 112 static bool
 113 compare_addr(struct fw3_address *a, struct fw3_address *b)
 114 {
 115         uint32_t mask;
 116
 117         if (a->family != FW3_FAMILY_V4)
 118                 return false;
 119
 120         mask = ~((1 << (32 - a->mask)) - 1);
 121
 122         return ((a->address.v4.s_addr & mask) == (b->address.v4.s_addr & mask));
 123 }
 124
 125 static bool
 126 resolve_dest(struct uci_element *e, struct fw3_redirect *redir,
 127              struct fw3_state *state)
 128 {
 129         struct fw3_zone *zone;
 130         struct fw3_address *addr;
 131         struct list_head *addrs;
 132
 133         if (!redir->ip_redir.set)
 134                 return false;
 135
 136         list_for_each_entry(zone, &state->zones, list)
 137         {
 138                 addrs = fw3_resolve_zone_addresses(zone);
 139
 140                 if (!addrs)
 141                         continue;
 142
 143                 list_for_each_entry(addr, addrs, list)
 144                 {
 145                         if (!compare_addr(addr, &redir->ip_redir))
 146                                 continue;
 147
 148                         strncpy(redir->dest.name, zone->name, sizeof(redir->dest.name));
 149                         redir->dest.set = true;
 150                         redir->_dest = zone;
 151
 152                         break;
 153                 }
 154
 155                 fw3_free_list(addrs);
 156
 157                 if (redir->_dest)
 158                         return true;
 159         }
 160
 161         return false;
 162 }
 163
 164 void
 165 fw3_load_redirects(struct fw3_state *state, struct uci_package *p)
 166 {
 167         struct uci_section *s;
 168         struct uci_element *e;
 169         struct fw3_redirect *redir;
 170
 171         bool valid;
 172
 173         INIT_LIST_HEAD(&state->redirects);
 174
 175         uci_foreach_element(&p->sections, e)
 176         {
 177                 s = uci_to_section(e);
 178
 179                 if (strcmp(s->type, "redirect"))
 180                         continue;
 181
 182                 redir = malloc(sizeof(*redir));
 183
 184                 if (!redir)
 185                         continue;
 186
 187                 memset(redir, 0, sizeof(*redir));
 188
 189                 INIT_LIST_HEAD(&redir->proto);
 190                 INIT_LIST_HEAD(&redir->mac_src);
 191
 192                 redir->enabled = true;
 193                 redir->reflection = true;
 194
 195                 valid = false;
 196
 197                 fw3_parse_options(redir, fw3_redirect_opts, s);
 198
 199                 if (!redir->enabled)
 200                 {
 201                         fw3_free_redirect(redir);
 202                         continue;
 203                 }
 204
 205                 if (redir->src.invert)
 206                 {
 207                         warn_elem(e, "must not have an inverted source");
 208                         fw3_free_redirect(redir);
 209                         continue;
 210                 }
 211                 else if (redir->src.set && !redir->src.any &&
 212                          !(redir->_src = fw3_lookup_zone(state, redir->src.name)))
 213                 {
 214                         warn_elem(e, "refers to not existing zone '%s'", redir->src.name);
 215                         fw3_free_redirect(redir);
 216                         continue;
 217                 }
 218                 else if (redir->dest.set && !redir->dest.any &&
 219                          !(redir->_dest = fw3_lookup_zone(state, redir->dest.name)))
 220                 {
 221                         warn_elem(e, "refers to not existing zone '%s'", redir->dest.name);
 222                         fw3_free_redirect(redir);
 223                         continue;
 224                 }
 225                 else if (redir->ipset.set && state->disable_ipsets)
 226                 {
 227                         warn_elem(e, "skipped due to disabled ipset support");
 228                         fw3_free_redirect(redir);
 229                         continue;
 230                 }
 231                 else if (redir->ipset.set && !redir->ipset.any &&
 232                          !(redir->_ipset = fw3_lookup_ipset(state, redir->ipset.name)))
 233                 {
 234                         warn_elem(e, "refers to unknown ipset '%s'", redir->ipset.name);
 235                         fw3_free_redirect(redir);
 236                         continue;
 237                 }
 238
 239                 if (!check_families(e, redir))
 240                 {
 241                         fw3_free_redirect(redir);
 242                         continue;
 243                 }
 244
 245                 if (redir->target == FW3_FLAG_UNSPEC)
 246                 {
 247                         warn_elem(e, "has no target specified, defaulting to DNAT");
 248                         redir->target = FW3_FLAG_DNAT;
 249                 }
 250                 else if (redir->target < FW3_FLAG_DNAT)
 251                 {
 252                         warn_elem(e, "has invalid target specified, defaulting to DNAT");
 253                         redir->target = FW3_FLAG_DNAT;
 254                 }
 255
 256                 if (redir->target == FW3_FLAG_DNAT)
 257                 {
 258                         if (redir->src.any)
 259                                 warn_elem(e, "must not have source '*' for DNAT target");
 260                         else if (!redir->_src)
 261                                 warn_elem(e, "has no source specified");
 262                         else
 263                         {
 264                                 set(redir->_src->flags, FW3_FAMILY_V4, redir->target);
 265                                 redir->_src->conntrack = true;
 266                                 valid = true;
 267                         }
 268
 269                         if (!redir->dest.set && resolve_dest(e, redir, state))
 270                         {
 271                                 warn_elem(e, "does not specify a destination, assuming '%s'",
 272                                           redir->dest.name);
 273                         }
 274
 275                         if (redir->reflection && redir->_dest && redir->_src->masq)
 276                         {
 277                                 set(redir->_dest->flags, FW3_FAMILY_V4, FW3_FLAG_ACCEPT);
 278                                 set(redir->_dest->flags, FW3_FAMILY_V4, FW3_FLAG_DNAT);
 279                                 set(redir->_dest->flags, FW3_FAMILY_V4, FW3_FLAG_SNAT);
 280                         }
 281                 }
 282                 else
 283                 {
 284                         if (redir->dest.any)
 285                                 warn_elem(e, "must not have destination '*' for SNAT target");
 286                         else if (!redir->_dest)
 287                                 warn_elem(e, "has no destination specified");
 288                         else if (!redir->ip_dest.set)
 289                                 warn_elem(e, "has no src_dip option specified");
 290                         else if (!list_empty(&redir->mac_src))
 291                                 warn_elem(e, "must not use 'src_mac' option for SNAT target");
 292                         else
 293                         {
 294                                 set(redir->_dest->flags, FW3_FAMILY_V4, redir->target);
 295                                 redir->_dest->conntrack = true;
 296                                 valid = true;
 297                         }
 298                 }
 299
 300                 if (list_empty(&redir->proto))
 301                 {
 302                         warn_elem(e, "does not specify a protocol, assuming TCP+UDP");
 303                         fw3_parse_protocol(&redir->proto, "tcpudp", true);
 304                 }
 305
 306                 if (!valid)
 307                 {
 308                         fw3_free_redirect(redir);
 309                         continue;
 310                 }
 311
 312                 if (!redir->port_redir.set)
 313                         redir->port_redir = redir->port_dest;
 314
 315                 list_add_tail(&redir->list, &state->redirects);
 316         }
 317 }
 318
 319 static void
 320 append_chain_nat(struct fw3_ipt_rule *r, struct fw3_redirect *redir)
 321 {
 322         if (redir->target == FW3_FLAG_DNAT)
 323                 fw3_ipt_rule_append(r, "zone_%s_prerouting", redir->src.name);
 324         else
 325                 fw3_ipt_rule_append(r, "zone_%s_postrouting", redir->dest.name);
 326 }
 327
 328 static void
 329 set_snat_dnat(struct fw3_ipt_rule *r, enum fw3_flag target,
 330               struct fw3_address *addr, struct fw3_port *port)
 331 {
 332         char buf[sizeof("255.255.255.255:65535-65535\0")];
 333
 334         buf[0] = '\0';
 335
 336         if (addr && addr->set)
 337         {
 338                 inet_ntop(AF_INET, &addr->address.v4, buf, sizeof(buf));
 339         }
 340
 341         if (port && port->set)
 342         {
 343                 if (port->port_min == port->port_max)
 344                         sprintf(buf + strlen(buf), ":%u", port->port_min);
 345                 else
 346                         sprintf(buf + strlen(buf), ":%u-%u",
 347                                 port->port_min, port->port_max);
 348         }
 349
 350         if (target == FW3_FLAG_DNAT)
 351         {
 352                 fw3_ipt_rule_target(r, "DNAT");
 353                 fw3_ipt_rule_addarg(r, false, "--to-destination", buf);
 354         }
 355         else
 356         {
 357                 fw3_ipt_rule_target(r, "SNAT");
 358                 fw3_ipt_rule_addarg(r, false, "--to-source", buf);
 359         }
 360 }
 361
 362 static void
 363 set_target_nat(struct fw3_ipt_rule *r, struct fw3_redirect *redir)
 364 {
 365         if (redir->target == FW3_FLAG_DNAT)
 366                 set_snat_dnat(r, redir->target, &redir->ip_redir, &redir->port_redir);
 367         else
 368                 set_snat_dnat(r, redir->target, &redir->ip_dest, &redir->port_dest);
 369 }
 370
 371 static void
 372 append_chain_filter(struct fw3_ipt_rule *r, struct fw3_redirect *redir)
 373 {
 374         if (redir->target == FW3_FLAG_DNAT)
 375         {
 376                 /* XXX: check for local ip */
 377                 if (!redir->ip_redir.set)
 378                         fw3_ipt_rule_append(r, "zone_%s_input", redir->src.name);
 379                 else
 380                         fw3_ipt_rule_append(r, "zone_%s_forward", redir->src.name);
 381         }
 382         else
 383         {
 384                 if (redir->src.set && !redir->src.any)
 385                         fw3_ipt_rule_append(r, "zone_%s_forward", redir->src.name);
 386                 else
 387                         fw3_ipt_rule_append(r, "delegate_forward");
 388         }
 389 }
 390
 391 static void
 392 set_target_filter(struct fw3_ipt_rule *r, struct fw3_redirect *redir)
 393 {
 394         /* XXX: check for local ip */
 395         if (redir->target == FW3_FLAG_DNAT && !redir->ip_redir.set)
 396                 fw3_ipt_rule_extra(r, "-m conntrack --ctstate DNAT");
 397
 398         fw3_ipt_rule_target(r, "ACCEPT");
 399 }
 400
 401 static void
 402 set_comment(struct fw3_ipt_rule *r, const char *name, int num, bool ref)
 403 {
 404         if (name)
 405         {
 406                 if (ref)
 407                         fw3_ipt_rule_comment(r, "%s (reflection)", name);
 408                 else
 409                         fw3_ipt_rule_comment(r, name);
 410         }
 411         else
 412         {
 413                 if (ref)
 414                         fw3_ipt_rule_comment(r, "@redirect[%u] (reflection)", num);
 415                 else
 416                         fw3_ipt_rule_comment(r, "@redirect[%u]", num);
 417         }
 418 }
 419
 420 static void
 421 print_redirect(struct fw3_ipt_handle *h, struct fw3_state *state,
 422                struct fw3_redirect *redir, int num,
 423                struct fw3_protocol *proto, struct fw3_mac *mac)
 424 {
 425         struct fw3_ipt_rule *r;
 426         struct fw3_address *src, *dst;
 427         struct fw3_port *spt, *dpt;
 428
 429         switch (h->table)
 430         {
 431         case FW3_TABLE_NAT:
 432                 src = &redir->ip_src;
 433                 dst = &redir->ip_dest;
 434                 spt = &redir->port_src;
 435                 dpt = &redir->port_dest;
 436
 437                 if (redir->target == FW3_FLAG_SNAT)
 438                 {
 439                         dst = &redir->ip_redir;
 440                         dpt = &redir->port_redir;
 441                 }
 442
 443                 r = fw3_ipt_rule_create(h, proto, NULL, NULL, src, dst);
 444                 fw3_ipt_rule_sport_dport(r, spt, dpt);
 445                 fw3_ipt_rule_mac(r, mac);
 446                 fw3_ipt_rule_ipset(r, redir->_ipset, redir->ipset.invert);
 447                 fw3_ipt_rule_time(r, &redir->time);
 448                 fw3_ipt_rule_mark(r, &redir->mark);
 449                 set_target_nat(r, redir);
 450                 fw3_ipt_rule_extra(r, redir->extra);
 451                 set_comment(r, redir->name, num, false);
 452                 append_chain_nat(r, redir);
 453                 break;
 454
 455         case FW3_TABLE_FILTER:
 456                 src = &redir->ip_src;
 457                 dst = &redir->ip_redir;
 458                 spt = &redir->port_src;
 459                 dpt = &redir->port_redir;
 460
 461                 r = fw3_ipt_rule_create(h, proto, NULL, NULL, src, dst);
 462                 fw3_ipt_rule_sport_dport(r, spt, dpt);
 463                 fw3_ipt_rule_mac(r, mac);
 464                 fw3_ipt_rule_ipset(r, redir->_ipset, redir->ipset.invert);
 465                 fw3_ipt_rule_time(r, &redir->time);
 466                 fw3_ipt_rule_mark(r, &redir->mark);
 467                 set_target_filter(r, redir);
 468                 fw3_ipt_rule_extra(r, redir->extra);
 469                 set_comment(r, redir->name, num, false);
 470                 append_chain_filter(r, redir);
 471                 break;
 472
 473         default:
 474                 break;
 475         }
 476 }
 477
 478 static void
 479 print_reflection(struct fw3_ipt_handle *h, struct fw3_state *state,
 480                  struct fw3_redirect *redir, int num,
 481                  struct fw3_protocol *proto, struct fw3_address *ra,
 482                  struct fw3_address *ia, struct fw3_address *ea)
 483 {
 484         struct fw3_ipt_rule *r;
 485
 486         switch (h->table)
 487         {
 488         case FW3_TABLE_NAT:
 489                 r = fw3_ipt_rule_create(h, proto, NULL, NULL, ia, ea);
 490                 fw3_ipt_rule_sport_dport(r, NULL, &redir->port_dest);
 491                 fw3_ipt_rule_time(r, &redir->time);
 492                 set_comment(r, redir->name, num, true);
 493                 set_snat_dnat(r, FW3_FLAG_DNAT, &redir->ip_redir, &redir->port_redir);
 494                 fw3_ipt_rule_append(r, "zone_%s_prerouting", redir->dest.name);
 495
 496                 r = fw3_ipt_rule_create(h, proto, NULL, NULL, ia, &redir->ip_redir);
 497                 fw3_ipt_rule_sport_dport(r, NULL, &redir->port_redir);
 498                 fw3_ipt_rule_time(r, &redir->time);
 499                 set_comment(r, redir->name, num, true);
 500                 set_snat_dnat(r, FW3_FLAG_SNAT, ra, NULL);
 501                 fw3_ipt_rule_append(r, "zone_%s_postrouting", redir->dest.name);
 502                 break;
 503
 504         case FW3_TABLE_FILTER:
 505                 r = fw3_ipt_rule_create(h, proto, NULL, NULL, ia, &redir->ip_redir);
 506                 fw3_ipt_rule_sport_dport(r, NULL, &redir->port_redir);
 507                 fw3_ipt_rule_time(r, &redir->time);
 508                 set_comment(r, redir->name, num, true);
 509                 fw3_ipt_rule_target(r, "zone_%s_dest_ACCEPT", redir->dest.name);
 510                 fw3_ipt_rule_append(r, "zone_%s_forward", redir->dest.name);
 511                 break;
 512
 513         default:
 514                 break;
 515         }
 516 }
 517
 518 static void
 519 expand_redirect(struct fw3_ipt_handle *handle, struct fw3_state *state,
 520                 struct fw3_redirect *redir, int num)
 521 {
 522         struct list_head *ext_addrs, *int_addrs;
 523         struct fw3_address *ext_addr, *int_addr, ref_addr;
 524         struct fw3_protocol *proto;
 525         struct fw3_mac *mac;
 526
 527         if (redir->name)
 528                 info("   * Redirect '%s'", redir->name);
 529         else
 530                 info("   * Redirect #%u", num);
 531
 532         if (!fw3_is_family(redir->_src, handle->family) ||
 533                 !fw3_is_family(redir->_dest, handle->family))
 534         {
 535                 info("     ! Skipping due to different family of zone");
 536                 return;
 537         }
 538
 539         if (!fw3_is_family(&redir->ip_src, handle->family) ||
 540             !fw3_is_family(&redir->ip_dest, handle->family) ||
 541                 !fw3_is_family(&redir->ip_redir, handle->family))
 542         {
 543                 if (!redir->ip_src.resolved ||
 544                     !redir->ip_dest.resolved ||
 545                     !redir->ip_redir.resolved)
 546                         info("     ! Skipping due to different family of ip address");
 547
 548                 return;
 549         }
 550
 551         if (redir->_ipset)
 552         {
 553                 if (!fw3_is_family(redir->_ipset, handle->family))
 554                 {
 555                         info("     ! Skipping due to different family in ipset");
 556                         return;
 557                 }
 558
 559                 if (!fw3_check_ipset(redir->_ipset))
 560                 {
 561                         info("     ! Skipping due to missing ipset '%s'",
 562                              redir->_ipset->external ?
 563                                         redir->_ipset->external : redir->_ipset->name);
 564                         return;
 565                 }
 566
 567                 set(redir->_ipset->flags, handle->family, handle->family);
 568         }
 569
 570         fw3_foreach(proto, &redir->proto)
 571         fw3_foreach(mac, &redir->mac_src)
 572                 print_redirect(handle, state, redir, num, proto, mac);
 573
 574         /* reflection rules */
 575         if (redir->target != FW3_FLAG_DNAT || !redir->reflection)
 576                 return;
 577
 578         if (!redir->_dest || !redir->_src->masq)
 579                 return;
 580
 581         ext_addrs = fw3_resolve_zone_addresses(redir->_src);
 582         int_addrs = fw3_resolve_zone_addresses(redir->_dest);
 583
 584         if (!ext_addrs || !int_addrs)
 585                 goto out;
 586
 587         list_for_each_entry(ext_addr, ext_addrs, list)
 588         {
 589                 if (!fw3_is_family(ext_addr, handle->family))
 590                         continue;
 591
 592                 list_for_each_entry(int_addr, int_addrs, list)
 593                 {
 594                         if (!fw3_is_family(int_addr, handle->family))
 595                                 continue;
 596
 597                         fw3_foreach(proto, &redir->proto)
 598                         {
 599                                 if (!proto || (proto->protocol != 6 && proto->protocol != 17))
 600                                         continue;
 601
 602                                 if (redir->reflection_src == FW3_REFLECTION_INTERNAL)
 603                                         ref_addr = *int_addr;
 604                                 else
 605                                         ref_addr = *ext_addr;
 606
 607                                 ref_addr.mask = 32;
 608                                 ext_addr->mask = 32;
 609
 610                                 print_reflection(handle, state, redir, num, proto,
 611                                                                  &ref_addr, int_addr, ext_addr);
 612                         }
 613                 }
 614         }
 615
 616 out:
 617         fw3_free_list(ext_addrs);
 618         fw3_free_list(int_addrs);
 619 }
 620
 621 void
 622 fw3_print_redirects(struct fw3_ipt_handle *handle, struct fw3_state *state)
 623 {
 624         int num = 0;
 625         struct fw3_redirect *redir;
 626
 627         if (handle->family == FW3_FAMILY_V6)
 628                 return;
 629
 630         if (handle->table != FW3_TABLE_FILTER && handle->table != FW3_TABLE_NAT)
 631                 return;
 632
 633         list_for_each_entry(redir, &state->redirects, list)
 634                 expand_redirect(handle, state, redir, num++);
 635 }