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 *rule, *opt;
 130         unsigned rem, orem;
 131
 132         INIT_LIST_HEAD(&state->snats);
 133
 134         blob_for_each_attr(rule, a, rem) {
 135                 const char *type = NULL;
 136                 const char *name = "ubus rule";
 137                 blobmsg_for_each_attr(opt, rule, orem)
 138                         if (!strcmp(blobmsg_name(opt), "type"))
 139                                 type = blobmsg_get_string(opt);
 140                         else if (!strcmp(blobmsg_name(opt), "name"))
 141                                 name = blobmsg_get_string(opt);
 142
 143                 if (!type || strcmp(type, "nat"))
 144                         continue;
 145
 146                 if (!(snat = alloc_snat(state)))
 147                         continue;
 148
 149                 if (!fw3_parse_blob_options(snat, fw3_snat_opts, rule, name))
 150                 {
 151                         fprintf(stderr, "%s skipped due to invalid options\n", name);
 152                         fw3_free_snat(snat);
 153                         continue;
 154                 }
 155         }
 156
 157         uci_foreach_element(&p->sections, e)
 158         {
 159                 s = uci_to_section(e);
 160
 161                 if (strcmp(s->type, "nat"))
 162                         continue;
 163
 164                 if (!(snat = alloc_snat(state)))
 165                         continue;
 166
 167                 if (!fw3_parse_options(snat, fw3_snat_opts, s))
 168                 {
 169                         warn_elem(e, "skipped due to invalid options");
 170                         fw3_free_snat(snat);
 171                         continue;
 172                 }
 173         }
 174
 175         list_for_each_entry_safe(snat, n, &state->snats, list)
 176         {
 177                 if (!snat->enabled)
 178                 {
 179                         fw3_free_snat(snat);
 180                         continue;
 181                 }
 182
 183                 if (snat->src.invert)
 184                 {
 185                         warn_elem(e, "must not have an inverted source");
 186                         fw3_free_snat(snat);
 187                         continue;
 188                 }
 189                 else if (snat->src.set && !snat->src.any &&
 190                          !(snat->_src = fw3_lookup_zone(state, snat->src.name)))
 191                 {
 192                         warn_elem(e, "refers to not existing zone '%s'", snat->src.name);
 193                         fw3_free_snat(snat);
 194                         continue;
 195                 }
 196                 else if (snat->ipset.set && state->disable_ipsets)
 197                 {
 198                         warn_elem(e, "skipped due to disabled ipset support");
 199                         fw3_free_snat(snat);
 200                         continue;
 201                 }
 202                 else if (snat->ipset.set &&
 203                          !(snat->ipset.ptr = fw3_lookup_ipset(state, snat->ipset.name)))
 204                 {
 205                         warn_elem(e, "refers to unknown ipset '%s'", snat->ipset.name);
 206                         fw3_free_snat(snat);
 207                         continue;
 208                 }
 209
 210                 if (!check_families(e, snat))
 211                 {
 212                         fw3_free_snat(snat);
 213                         continue;
 214                 }
 215
 216                 if (snat->target == FW3_FLAG_UNSPEC)
 217                 {
 218                         warn_elem(e, "has no target specified, defaulting to MASQUERADE");
 219                         snat->target = FW3_FLAG_MASQUERADE;
 220                 }
 221                 else if (snat->target != FW3_FLAG_ACCEPT && snat->target != FW3_FLAG_SNAT &&
 222                                 snat->target != FW3_FLAG_MASQUERADE)
 223                 {
 224                         warn_elem(e, "has invalid target specified, defaulting to MASQUERADE");
 225                         snat->target = FW3_FLAG_MASQUERADE;
 226                 }
 227
 228                 if (snat->target == FW3_FLAG_SNAT &&
 229                     !snat->ip_snat.set && !snat->port_snat.set)
 230                 {
 231                         warn_elem(e, "needs either 'snat_ip' or 'snat_port' for SNAT");
 232                         fw3_free_snat(snat);
 233                         continue;
 234                 }
 235                 else if (snat->target != FW3_FLAG_SNAT && snat->ip_snat.set)
 236                 {
 237                         warn_elem(e, "must not use 'snat_ip' for non-SNAT");
 238                         fw3_free_snat(snat);
 239                         continue;
 240                 }
 241                 else if (snat->target != FW3_FLAG_SNAT && snat->port_snat.set)
 242                 {
 243                         warn_elem(e, "must not use 'snat_port' for non-SNAT");
 244                         fw3_free_snat(snat);
 245                         continue;
 246                 }
 247
 248                 if (list_empty(&snat->proto))
 249                 {
 250                         warn_elem(e, "does not specify a protocol, assuming all");
 251                         fw3_parse_protocol(&snat->proto, "all", true);
 252                 }
 253
 254                 if (snat->_src)
 255                         set(snat->_src->flags, FW3_FAMILY_V4, FW3_FLAG_SNAT);
 256         }
 257 }
 258
 259 static void
 260 append_chain(struct fw3_ipt_rule *r, struct fw3_snat *snat)
 261 {
 262         if (snat->_src)
 263                 fw3_ipt_rule_append(r, "zone_%s_postrouting", snat->src.name);
 264         else
 265                 fw3_ipt_rule_append(r, "POSTROUTING");
 266 }
 267
 268 static void
 269 set_target(struct fw3_ipt_rule *r, struct fw3_snat *snat,
 270            struct fw3_protocol *proto)
 271 {
 272         char buf[sizeof("255.255.255.255:65535-65535\0")];
 273
 274         if (snat->target == FW3_FLAG_SNAT)
 275         {
 276                 buf[0] = '\0';
 277
 278                 if (snat->ip_snat.set)
 279                 {
 280                         inet_ntop(AF_INET, &snat->ip_snat.address.v4, buf, sizeof(buf));
 281                 }
 282
 283                 if (snat->port_snat.set && proto && !proto->any &&
 284                     (proto->protocol == 6 || proto->protocol == 17 || proto->protocol == 1))
 285                 {
 286                         if (snat->port_snat.port_min == snat->port_snat.port_max)
 287                                 sprintf(buf + strlen(buf), ":%u", snat->port_snat.port_min);
 288                         else
 289                                 sprintf(buf + strlen(buf), ":%u-%u",
 290                                                 snat->port_snat.port_min, snat->port_snat.port_max);
 291
 292                         if (snat->connlimit_ports) {
 293                                 char portcntbuf[6];
 294                                 snprintf(portcntbuf, sizeof(portcntbuf), "%u",
 295                                                 1 + snat->port_snat.port_max - snat->port_snat.port_min);
 296
 297                                 fw3_ipt_rule_addarg(r, false, "-m", "connlimit");
 298                                 fw3_ipt_rule_addarg(r, false, "--connlimit-daddr", NULL);
 299                                 fw3_ipt_rule_addarg(r, false, "--connlimit-upto", portcntbuf);
 300                         }
 301                 }
 302
 303                 fw3_ipt_rule_target(r, "SNAT");
 304                 fw3_ipt_rule_addarg(r, false, "--to-source", buf);
 305         }
 306         else if (snat->target == FW3_FLAG_ACCEPT)
 307         {
 308                 fw3_ipt_rule_target(r, "ACCEPT");
 309         }
 310         else
 311         {
 312                 fw3_ipt_rule_target(r, "MASQUERADE");
 313         }
 314 }
 315
 316 static void
 317 set_comment(struct fw3_ipt_rule *r, const char *name, int num)
 318 {
 319         if (name)
 320                 fw3_ipt_rule_comment(r, name);
 321         else
 322                 fw3_ipt_rule_comment(r, "@nat[%u]", num);
 323 }
 324
 325 static void
 326 print_snat(struct fw3_ipt_handle *h, struct fw3_state *state,
 327            struct fw3_snat *snat, int num, struct fw3_protocol *proto)
 328 {
 329         struct fw3_ipt_rule *r;
 330         struct fw3_address *src, *dst;
 331         struct fw3_port *spt, *dpt;
 332
 333         switch (h->table)
 334         {
 335         case FW3_TABLE_NAT:
 336                 src = &snat->ip_src;
 337                 dst = &snat->ip_dest;
 338                 spt = &snat->port_src;
 339                 dpt = &snat->port_dest;
 340
 341                 r = fw3_ipt_rule_create(h, proto, NULL, NULL, src, dst);
 342                 fw3_ipt_rule_sport_dport(r, spt, dpt);
 343                 fw3_ipt_rule_device(r, snat->device, true);
 344                 fw3_ipt_rule_ipset(r, &snat->ipset);
 345                 fw3_ipt_rule_limit(r, &snat->limit);
 346                 fw3_ipt_rule_time(r, &snat->time);
 347                 fw3_ipt_rule_mark(r, &snat->mark);
 348                 set_target(r, snat, proto);
 349                 fw3_ipt_rule_extra(r, snat->extra);
 350                 set_comment(r, snat->name, num);
 351                 append_chain(r, snat);
 352                 break;
 353
 354         default:
 355                 break;
 356         }
 357 }
 358
 359 static void
 360 expand_snat(struct fw3_ipt_handle *handle, struct fw3_state *state,
 361                 struct fw3_snat *snat, int num)
 362 {
 363         struct fw3_protocol *proto;
 364
 365         if (snat->name)
 366                 info("   * NAT '%s'", snat->name);
 367         else
 368                 info("   * NAT #%u", num);
 369
 370         if (!fw3_is_family(snat->_src, handle->family))
 371         {
 372                 info("     ! Skipping due to different family of zone");
 373                 return;
 374         }
 375
 376         if (!fw3_is_family(&snat->ip_src, handle->family) ||
 377             !fw3_is_family(&snat->ip_dest, handle->family) ||
 378                 !fw3_is_family(&snat->ip_snat, handle->family))
 379         {
 380                 if (!snat->ip_src.resolved ||
 381                     !snat->ip_dest.resolved ||
 382                     !snat->ip_snat.resolved)
 383                         info("     ! Skipping due to different family of ip address");
 384
 385                 return;
 386         }
 387
 388         if (snat->ipset.ptr)
 389         {
 390                 if (!fw3_is_family(snat->ipset.ptr, handle->family))
 391                 {
 392                         info("     ! Skipping due to different family in ipset");
 393                         return;
 394                 }
 395
 396                 if (!fw3_check_ipset(snat->ipset.ptr))
 397                 {
 398                         info("     ! Skipping due to missing ipset '%s'",
 399                              snat->ipset.ptr->external ?
 400                                         snat->ipset.ptr->external : snat->ipset.ptr->name);
 401                         return;
 402                 }
 403
 404                 set(snat->ipset.ptr->flags, handle->family, handle->family);
 405         }
 406
 407         fw3_foreach(proto, &snat->proto)
 408                 print_snat(handle, state, snat, num, proto);
 409 }
 410
 411 void
 412 fw3_print_snats(struct fw3_ipt_handle *handle, struct fw3_state *state)
 413 {
 414         int num = 0;
 415         struct fw3_snat *snat;
 416
 417         if (handle->family == FW3_FAMILY_V6)
 418                 return;
 419
 420         if (handle->table != FW3_TABLE_NAT)
 421                 return;
 422
 423         list_for_each_entry(snat, &state->snats, list)
 424                 expand_snat(handle, state, snat, num++);
 425 }