src/charon/sa/tasks/ike_natd.c

   1 /*
   2  * Copyright (C) 2006-2007 Martin Willi
   3  * Copyright (C) 2006 Tobias Brunner, Daniel Roethlisberger
   4  * Hochschule fuer Technik Rapperswil
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; either version 2 of the License, or (at your
   9  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  13  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * for more details.
  15  */
  16
  17 #include "ike_natd.h"
  18
  19 #include <string.h>
  20
  21 #include <daemon.h>
  22 #include <config/peer_cfg.h>
  23 #include <crypto/hashers/hasher.h>
  24 #include <encoding/payloads/notify_payload.h>
  25
  26
  27 typedef struct private_ike_natd_t private_ike_natd_t;
  28
  29 /**
  30  * Private members of a ike_natd_t task.
  31  */
  32 struct private_ike_natd_t {
  33
  34         /**
  35          * Public methods and task_t interface.
  36          */
  37         ike_natd_t public;
  38
  39         /**
  40          * Assigned IKE_SA.
  41          */
  42         ike_sa_t *ike_sa;
  43
  44         /**
  45          * Are we the initiator?
  46          */
  47         bool initiator;
  48
  49         /**
  50          * Hasher used to build NAT detection hashes
  51          */
  52         hasher_t *hasher;
  53
  54         /**
  55          * Did we process any NAT detection notifys for a source address?
  56          */
  57         bool src_seen;
  58
  59         /**
  60          * Did we process any NAT detection notifys for a destination address?
  61          */
  62         bool dst_seen;
  63
  64         /**
  65          * Have we found a matching source address NAT hash?
  66          */
  67         bool src_matched;
  68
  69         /**
  70          * Have we found a matching destination address NAT hash?
  71          */
  72         bool dst_matched;
  73
  74         /**
  75          * whether NAT mappings for our NATed address has changed
  76          */
  77         bool mapping_changed;
  78 };
  79
  80
  81 /**
  82  * Build NAT detection hash for a host
  83  */
  84 static chunk_t generate_natd_hash(private_ike_natd_t *this,
  85                                                                   ike_sa_id_t *ike_sa_id, host_t *host)
  86 {
  87         chunk_t natd_chunk, spi_i_chunk, spi_r_chunk, addr_chunk, port_chunk;
  88         chunk_t natd_hash;
  89         u_int64_t spi_i, spi_r;
  90         u_int16_t port;
  91
  92         /* prepare all required chunks */
  93         spi_i = ike_sa_id->get_initiator_spi(ike_sa_id);
  94         spi_r = ike_sa_id->get_responder_spi(ike_sa_id);
  95         spi_i_chunk.ptr = (void*)&spi_i;
  96         spi_i_chunk.len = sizeof(spi_i);
  97         spi_r_chunk.ptr = (void*)&spi_r;
  98         spi_r_chunk.len = sizeof(spi_r);
  99         port = htons(host->get_port(host));
 100         port_chunk.ptr = (void*)&port;
 101         port_chunk.len = sizeof(port);
 102         addr_chunk = host->get_address(host);
 103
 104         /*  natd_hash = SHA1( spi_i | spi_r | address | port ) */
 105         natd_chunk = chunk_cat("cccc", spi_i_chunk, spi_r_chunk, addr_chunk, port_chunk);
 106         this->hasher->allocate_hash(this->hasher, natd_chunk, &natd_hash);
 107         DBG3(DBG_IKE, "natd_chunk %B", &natd_chunk);
 108         DBG3(DBG_IKE, "natd_hash %B", &natd_hash);
 109
 110         chunk_free(&natd_chunk);
 111         return natd_hash;
 112 }
 113
 114 /**
 115  * build a faked NATD payload to enforce UDP encap
 116  */
 117 static chunk_t generate_natd_hash_faked(private_ike_natd_t *this)
 118 {
 119         rng_t *rng;
 120         chunk_t chunk;
 121
 122         rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK);
 123         if (!rng)
 124         {
 125                 DBG1(DBG_IKE, "unable to get random bytes for NATD fake");
 126                 return chunk_empty;
 127         }
 128         rng->allocate_bytes(rng, HASH_SIZE_SHA1, &chunk);
 129         rng->destroy(rng);
 130         return chunk;
 131 }
 132
 133 /**
 134  * Build a NAT detection notify payload.
 135  */
 136 static notify_payload_t *build_natd_payload(private_ike_natd_t *this,
 137                                                                                         notify_type_t type, host_t *host)
 138 {
 139         chunk_t hash;
 140         notify_payload_t *notify;
 141         ike_sa_id_t *ike_sa_id;
 142         ike_cfg_t *config;
 143
 144         ike_sa_id = this->ike_sa->get_id(this->ike_sa);
 145         config = this->ike_sa->get_ike_cfg(this->ike_sa);
 146         if (config->force_encap(config) && type == NAT_DETECTION_SOURCE_IP)
 147         {
 148                 hash = generate_natd_hash_faked(this);
 149         }
 150         else
 151         {
 152                 hash = generate_natd_hash(this, ike_sa_id, host);
 153         }
 154         notify = notify_payload_create();
 155         notify->set_notify_type(notify, type);
 156         notify->set_notification_data(notify, hash);
 157         chunk_free(&hash);
 158
 159         return notify;
 160 }
 161
 162 /**
 163  * read notifys from message and evaluate them
 164  */
 165 static void process_payloads(private_ike_natd_t *this, message_t *message)
 166 {
 167         enumerator_t *enumerator;
 168         payload_t *payload;
 169         notify_payload_t *notify;
 170         chunk_t hash, src_hash, dst_hash;
 171         ike_sa_id_t *ike_sa_id;
 172         host_t *me, *other;
 173         ike_cfg_t *config;
 174
 175         /* Precompute NAT-D hashes for incoming NAT notify comparison */
 176         ike_sa_id = message->get_ike_sa_id(message);
 177         me = message->get_destination(message);
 178         other = message->get_source(message);
 179         dst_hash = generate_natd_hash(this, ike_sa_id, me);
 180         src_hash = generate_natd_hash(this, ike_sa_id, other);
 181
 182         DBG3(DBG_IKE, "precalculated src_hash %B", &src_hash);
 183         DBG3(DBG_IKE, "precalculated dst_hash %B", &dst_hash);
 184
 185         enumerator = message->create_payload_enumerator(message);
 186         while (enumerator->enumerate(enumerator, &payload))
 187         {
 188                 if (payload->get_type(payload) != NOTIFY)
 189                 {
 190                         continue;
 191                 }
 192                 notify = (notify_payload_t*)payload;
 193                 switch (notify->get_notify_type(notify))
 194                 {
 195                         case NAT_DETECTION_DESTINATION_IP:
 196                         {
 197                                 this->dst_seen = TRUE;
 198                                 hash = notify->get_notification_data(notify);
 199                                 if (!this->dst_matched)
 200                                 {
 201                                         DBG3(DBG_IKE, "received dst_hash %B", &hash);
 202                                         if (chunk_equals(hash, dst_hash))
 203                                         {
 204                                                 this->dst_matched = TRUE;
 205                                         }
 206                                 }
 207                                 /* RFC4555 says we should also compare against IKE_SA_INIT
 208                                  * NATD payloads, but this does not work: We are running
 209                                  * there at port 500, but use 4500 afterwards... */
 210                                 if (message->get_exchange_type(message) == INFORMATIONAL &&
 211                                         this->initiator && !this->dst_matched)
 212                                 {
 213                                         this->mapping_changed = this->ike_sa->has_mapping_changed(
 214                                                                                                                         this->ike_sa, hash);
 215                                 }
 216                                 break;
 217                         }
 218                         case NAT_DETECTION_SOURCE_IP:
 219                         {
 220                                 this->src_seen = TRUE;
 221                                 if (!this->src_matched)
 222                                 {
 223                                         hash = notify->get_notification_data(notify);
 224                                         DBG3(DBG_IKE, "received src_hash %B", &hash);
 225                                         if (chunk_equals(hash, src_hash))
 226                                         {
 227                                                 this->src_matched = TRUE;
 228                                         }
 229                                 }
 230                                 break;
 231                         }
 232                         default:
 233                                 break;
 234                 }
 235         }
 236         enumerator->destroy(enumerator);
 237
 238         chunk_free(&src_hash);
 239         chunk_free(&dst_hash);
 240
 241         if (this->src_seen && this->dst_seen)
 242         {
 243                 this->ike_sa->enable_extension(this->ike_sa, EXT_NATT);
 244
 245                 this->ike_sa->set_condition(this->ike_sa, COND_NAT_HERE,
 246                                                                         !this->dst_matched);
 247                 this->ike_sa->set_condition(this->ike_sa, COND_NAT_THERE,
 248                                                                         !this->src_matched);
 249                 config = this->ike_sa->get_ike_cfg(this->ike_sa);
 250                 if (this->dst_matched && this->src_matched &&
 251                         config->force_encap(config))
 252                 {
 253                         this->ike_sa->set_condition(this->ike_sa, COND_NAT_FAKE, TRUE);
 254                 }
 255         }
 256 }
 257
 258 /**
 259  * Implementation of task_t.process for initiator
 260  */
 261 static status_t process_i(private_ike_natd_t *this, message_t *message)
 262 {
 263         process_payloads(this, message);
 264
 265         if (message->get_exchange_type(message) == IKE_SA_INIT)
 266         {
 267                 peer_cfg_t *peer_cfg = this->ike_sa->get_peer_cfg(this->ike_sa);
 268
 269 #ifdef ME
 270                 /* if we are on a mediated connection we have already switched to
 271                  * port 4500 and the correct destination port is already configured,
 272                  * therefore we must not switch again */
 273                 if (peer_cfg->get_mediated_by(peer_cfg))
 274                 {
 275                         return SUCCESS;
 276                 }
 277 #endif /* ME */
 278
 279                 if (this->ike_sa->has_condition(this->ike_sa, COND_NAT_ANY) ||
 280 #ifdef ME
 281                         /* if we are on a mediation connection we switch to port 4500 even
 282                          * if no NAT is detected. */
 283                         peer_cfg->is_mediation(peer_cfg) ||
 284 #endif /* ME */
 285                         /* if peer supports NAT-T, we switch to port 4500 even
 286                          * if no NAT is detected. MOBIKE requires this. */
 287                         (peer_cfg->use_mobike(peer_cfg) &&
 288                          this->ike_sa->supports_extension(this->ike_sa, EXT_NATT)))
 289                 {
 290                         host_t *me, *other;
 291
 292                         /* do not switch if we have a custom port from mobike/NAT */
 293                         me = this->ike_sa->get_my_host(this->ike_sa);
 294                         if (me->get_port(me) == IKEV2_UDP_PORT)
 295                         {
 296                                 me->set_port(me, IKEV2_NATT_PORT);
 297                         }
 298                         other = this->ike_sa->get_other_host(this->ike_sa);
 299                         if (other->get_port(other) == IKEV2_UDP_PORT)
 300                         {
 301                                 other->set_port(other, IKEV2_NATT_PORT);
 302                         }
 303                 }
 304         }
 305
 306         return SUCCESS;
 307 }
 308
 309 /**
 310  * Implementation of task_t.process for initiator
 311  */
 312 static status_t build_i(private_ike_natd_t *this, message_t *message)
 313 {
 314         notify_payload_t *notify;
 315         enumerator_t *enumerator;
 316         host_t *host;
 317
 318         if (this->hasher == NULL)
 319         {
 320                 DBG1(DBG_IKE, "unable to build NATD payloads, SHA1 not supported");
 321                 return NEED_MORE;
 322         }
 323
 324         /* destination is always set */
 325         host = message->get_destination(message);
 326         notify = build_natd_payload(this, NAT_DETECTION_DESTINATION_IP, host);
 327         message->add_payload(message, (payload_t*)notify);
 328
 329         /* source may be any, we have 3 possibilities to get our source address:
 330          * 1. It is defined in the config => use the one of the IKE_SA
 331          * 2. We do a routing lookup in the kernel interface
 332          * 3. Include all possbile addresses
 333          */
 334         host = message->get_source(message);
 335         if (!host->is_anyaddr(host))
 336         {       /* 1. */
 337                 notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
 338                 message->add_payload(message, (payload_t*)notify);
 339         }
 340         else
 341         {
 342                 host = charon->kernel_interface->get_source_addr(charon->kernel_interface,
 343                                                         this->ike_sa->get_other_host(this->ike_sa), NULL);
 344                 if (host)
 345                 {       /* 2. */
 346                         host->set_port(host, IKEV2_UDP_PORT);
 347                         notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
 348                         message->add_payload(message, (payload_t*)notify);
 349                         host->destroy(host);
 350                 }
 351                 else
 352                 {       /* 3. */
 353                         enumerator = charon->kernel_interface->create_address_enumerator(
 354                                                                                 charon->kernel_interface, FALSE, FALSE);
 355                         while (enumerator->enumerate(enumerator, (void**)&host))
 356                         {
 357                                 /* apply port 500 to host, but work on a copy */
 358                                 host = host->clone(host);
 359                                 host->set_port(host, IKEV2_UDP_PORT);
 360                                 notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
 361                                 host->destroy(host);
 362                                 message->add_payload(message, (payload_t*)notify);
 363                         }
 364                         enumerator->destroy(enumerator);
 365                 }
 366         }
 367         return NEED_MORE;
 368 }
 369
 370 /**
 371  * Implementation of task_t.build for responder
 372  */
 373 static status_t build_r(private_ike_natd_t *this, message_t *message)
 374 {
 375         notify_payload_t *notify;
 376         host_t *me, *other;
 377
 378         /* only add notifies on successfull responses. */
 379         if (message->get_exchange_type(message) == IKE_SA_INIT &&
 380                 message->get_payload(message, SECURITY_ASSOCIATION) == NULL)
 381         {
 382                 return SUCCESS;
 383         }
 384
 385         if (this->src_seen && this->dst_seen)
 386         {
 387                 if (this->hasher == NULL)
 388                 {
 389                         DBG1(DBG_IKE, "unable to build NATD payloads, SHA1 not supported");
 390                         return SUCCESS;
 391                 }
 392
 393                 /* initiator seems to support NAT detection, add response */
 394                 me = message->get_source(message);
 395                 notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, me);
 396                 message->add_payload(message, (payload_t*)notify);
 397
 398                 other = message->get_destination(message);
 399                 notify = build_natd_payload(this, NAT_DETECTION_DESTINATION_IP, other);
 400                 message->add_payload(message, (payload_t*)notify);
 401         }
 402         return SUCCESS;
 403 }
 404
 405 /**
 406  * Implementation of task_t.process for responder
 407  */
 408 static status_t process_r(private_ike_natd_t *this, message_t *message)
 409 {
 410         process_payloads(this, message);
 411
 412         return NEED_MORE;
 413 }
 414
 415 /**
 416  * Implementation of task_t.get_type
 417  */
 418 static task_type_t get_type(private_ike_natd_t *this)
 419 {
 420         return IKE_NATD;
 421 }
 422
 423 /**
 424  * Implementation of task_t.migrate
 425  */
 426 static void migrate(private_ike_natd_t *this, ike_sa_t *ike_sa)
 427 {
 428         this->ike_sa = ike_sa;
 429         this->src_seen = FALSE;
 430         this->dst_seen = FALSE;
 431         this->src_matched = FALSE;
 432         this->dst_matched = FALSE;
 433         this->mapping_changed = FALSE;
 434 }
 435
 436 /**
 437  * Implementation of ike_natd_t.has_mapping_changed
 438  */
 439 static bool has_mapping_changed(private_ike_natd_t *this)
 440 {
 441         return this->mapping_changed;
 442 }
 443
 444 /**
 445  * Implementation of task_t.destroy
 446  */
 447 static void destroy(private_ike_natd_t *this)
 448 {
 449         DESTROY_IF(this->hasher);
 450         free(this);
 451 }
 452
 453 /*
 454  * Described in header.
 455  */
 456 ike_natd_t *ike_natd_create(ike_sa_t *ike_sa, bool initiator)
 457 {
 458         private_ike_natd_t *this = malloc_thing(private_ike_natd_t);
 459
 460         this->public.task.get_type = (task_type_t(*)(task_t*))get_type;
 461         this->public.task.migrate = (void(*)(task_t*,ike_sa_t*))migrate;
 462         this->public.task.destroy = (void(*)(task_t*))destroy;
 463
 464         if (initiator)
 465         {
 466                 this->public.task.build = (status_t(*)(task_t*,message_t*))build_i;
 467                 this->public.task.process = (status_t(*)(task_t*,message_t*))process_i;
 468         }
 469         else
 470         {
 471                 this->public.task.build = (status_t(*)(task_t*,message_t*))build_r;
 472                 this->public.task.process = (status_t(*)(task_t*,message_t*))process_r;
 473         }
 474
 475         this->public.has_mapping_changed = (bool(*)(ike_natd_t*))has_mapping_changed;
 476
 477         this->ike_sa = ike_sa;
 478         this->initiator = initiator;
 479         this->hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1);
 480         this->src_seen = FALSE;
 481         this->dst_seen = FALSE;
 482         this->src_matched = FALSE;
 483         this->dst_matched = FALSE;
 484         this->mapping_changed = FALSE;
 485
 486         return &this->public;
 487 }