diff options
Diffstat (limited to 'src/libcharon/sa/ikev2/tasks/ike_natd.c')
| -rw-r--r-- | src/libcharon/sa/ikev2/tasks/ike_natd.c | 472 |
1 files changed, 472 insertions, 0 deletions
diff --git a/src/libcharon/sa/ikev2/tasks/ike_natd.c b/src/libcharon/sa/ikev2/tasks/ike_natd.c new file mode 100644 index 000000000..0a93db9ed --- /dev/null +++ b/src/libcharon/sa/ikev2/tasks/ike_natd.c @@ -0,0 +1,472 @@ +/* + * Copyright (C) 2006-2007 Martin Willi + * Copyright (C) 2006 Tobias Brunner, Daniel Roethlisberger + * Hochschule fuer Technik Rapperswil + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY + * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * for more details. + */ + +#include "ike_natd.h" + +#include <string.h> + +#include <hydra.h> +#include <daemon.h> +#include <config/peer_cfg.h> +#include <crypto/hashers/hasher.h> +#include <encoding/payloads/notify_payload.h> + + +typedef struct private_ike_natd_t private_ike_natd_t; + +/** + * Private members of a ike_natd_t task. + */ +struct private_ike_natd_t { + + /** + * Public methods and task_t interface. + */ + ike_natd_t public; + + /** + * Assigned IKE_SA. + */ + ike_sa_t *ike_sa; + + /** + * Are we the initiator? + */ + bool initiator; + + /** + * Hasher used to build NAT detection hashes + */ + hasher_t *hasher; + + /** + * Did we process any NAT detection notifys for a source address? + */ + bool src_seen; + + /** + * Did we process any NAT detection notifys for a destination address? + */ + bool dst_seen; + + /** + * Have we found a matching source address NAT hash? + */ + bool src_matched; + + /** + * Have we found a matching destination address NAT hash? + */ + bool dst_matched; + + /** + * whether NAT mappings for our NATed address has changed + */ + bool mapping_changed; +}; + + +/** + * Build NAT detection hash for a host + */ +static chunk_t generate_natd_hash(private_ike_natd_t *this, + ike_sa_id_t *ike_sa_id, host_t *host) +{ + chunk_t natd_chunk, spi_i_chunk, spi_r_chunk, addr_chunk, port_chunk; + chunk_t natd_hash; + u_int64_t spi_i, spi_r; + u_int16_t port; + + /* prepare all required chunks */ + spi_i = ike_sa_id->get_initiator_spi(ike_sa_id); + spi_r = ike_sa_id->get_responder_spi(ike_sa_id); + spi_i_chunk.ptr = (void*)&spi_i; + spi_i_chunk.len = sizeof(spi_i); + spi_r_chunk.ptr = (void*)&spi_r; + spi_r_chunk.len = sizeof(spi_r); + port = htons(host->get_port(host)); + port_chunk.ptr = (void*)&port; + port_chunk.len = sizeof(port); + addr_chunk = host->get_address(host); + + /* natd_hash = SHA1( spi_i | spi_r | address | port ) */ + natd_chunk = chunk_cat("cccc", spi_i_chunk, spi_r_chunk, addr_chunk, port_chunk); + if (!this->hasher->allocate_hash(this->hasher, natd_chunk, &natd_hash)) + { + natd_hash = chunk_empty; + } + DBG3(DBG_IKE, "natd_chunk %B", &natd_chunk); + DBG3(DBG_IKE, "natd_hash %B", &natd_hash); + + chunk_free(&natd_chunk); + return natd_hash; +} + +/** + * build a faked NATD payload to enforce UDP encap + */ +static chunk_t generate_natd_hash_faked(private_ike_natd_t *this) +{ + rng_t *rng; + chunk_t chunk; + + rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK); + if (!rng || !rng->allocate_bytes(rng, HASH_SIZE_SHA1, &chunk)) + { + DBG1(DBG_IKE, "unable to get random bytes for NATD fake"); + DESTROY_IF(rng); + return chunk_empty; + } + rng->destroy(rng); + return chunk; +} + +/** + * Build a NAT detection notify payload. + */ +static notify_payload_t *build_natd_payload(private_ike_natd_t *this, + notify_type_t type, host_t *host) +{ + chunk_t hash; + notify_payload_t *notify; + ike_sa_id_t *ike_sa_id; + ike_cfg_t *config; + + ike_sa_id = this->ike_sa->get_id(this->ike_sa); + config = this->ike_sa->get_ike_cfg(this->ike_sa); + if (config->force_encap(config) && type == NAT_DETECTION_SOURCE_IP) + { + hash = generate_natd_hash_faked(this); + } + else + { + hash = generate_natd_hash(this, ike_sa_id, host); + } + if (!hash.len) + { + return NULL; + } + notify = notify_payload_create(NOTIFY); + notify->set_notify_type(notify, type); + notify->set_notification_data(notify, hash); + chunk_free(&hash); + + return notify; +} + +/** + * read notifys from message and evaluate them + */ +static void process_payloads(private_ike_natd_t *this, message_t *message) +{ + enumerator_t *enumerator; + payload_t *payload; + notify_payload_t *notify; + chunk_t hash, src_hash, dst_hash; + ike_sa_id_t *ike_sa_id; + host_t *me, *other; + ike_cfg_t *config; + + /* Precompute NAT-D hashes for incoming NAT notify comparison */ + ike_sa_id = message->get_ike_sa_id(message); + me = message->get_destination(message); + other = message->get_source(message); + dst_hash = generate_natd_hash(this, ike_sa_id, me); + src_hash = generate_natd_hash(this, ike_sa_id, other); + + DBG3(DBG_IKE, "precalculated src_hash %B", &src_hash); + DBG3(DBG_IKE, "precalculated dst_hash %B", &dst_hash); + + enumerator = message->create_payload_enumerator(message); + while (enumerator->enumerate(enumerator, &payload)) + { + if (payload->get_type(payload) != NOTIFY) + { + continue; + } + notify = (notify_payload_t*)payload; + switch (notify->get_notify_type(notify)) + { + case NAT_DETECTION_DESTINATION_IP: + { + this->dst_seen = TRUE; + hash = notify->get_notification_data(notify); + if (!this->dst_matched) + { + DBG3(DBG_IKE, "received dst_hash %B", &hash); + if (chunk_equals(hash, dst_hash)) + { + this->dst_matched = TRUE; + } + } + /* RFC4555 says we should also compare against IKE_SA_INIT + * NATD payloads, but this does not work: We are running + * there at port 500, but use 4500 afterwards... */ + if (message->get_exchange_type(message) == INFORMATIONAL && + this->initiator && !this->dst_matched) + { + this->mapping_changed = this->ike_sa->has_mapping_changed( + this->ike_sa, hash); + } + break; + } + case NAT_DETECTION_SOURCE_IP: + { + this->src_seen = TRUE; + if (!this->src_matched) + { + hash = notify->get_notification_data(notify); + DBG3(DBG_IKE, "received src_hash %B", &hash); + if (chunk_equals(hash, src_hash)) + { + this->src_matched = TRUE; + } + } + break; + } + default: + break; + } + } + enumerator->destroy(enumerator); + + chunk_free(&src_hash); + chunk_free(&dst_hash); + + if (this->src_seen && this->dst_seen) + { + this->ike_sa->enable_extension(this->ike_sa, EXT_NATT); + + this->ike_sa->set_condition(this->ike_sa, COND_NAT_HERE, + !this->dst_matched); + this->ike_sa->set_condition(this->ike_sa, COND_NAT_THERE, + !this->src_matched); + config = this->ike_sa->get_ike_cfg(this->ike_sa); + if (this->dst_matched && this->src_matched && + config->force_encap(config)) + { + this->ike_sa->set_condition(this->ike_sa, COND_NAT_FAKE, TRUE); + } + } +} + +METHOD(task_t, process_i, status_t, + private_ike_natd_t *this, message_t *message) +{ + process_payloads(this, message); + + if (message->get_exchange_type(message) == IKE_SA_INIT) + { + peer_cfg_t *peer_cfg = this->ike_sa->get_peer_cfg(this->ike_sa); + if (this->ike_sa->has_condition(this->ike_sa, COND_NAT_ANY) || + /* if peer supports NAT-T, we switch to port 4500 even + * if no NAT is detected. can't be done later (when we would know + * whether the peer supports MOBIKE) because there would be no + * exchange to actually do the switch (other than a forced DPD). */ + (peer_cfg->use_mobike(peer_cfg) && + this->ike_sa->supports_extension(this->ike_sa, EXT_NATT))) + { + this->ike_sa->float_ports(this->ike_sa); + } + } + + return SUCCESS; +} + +METHOD(task_t, build_i, status_t, + private_ike_natd_t *this, message_t *message) +{ + notify_payload_t *notify; + enumerator_t *enumerator; + ike_cfg_t *ike_cfg; + host_t *host; + + if (this->hasher == NULL) + { + DBG1(DBG_IKE, "unable to build NATD payloads, SHA1 not supported"); + return NEED_MORE; + } + + ike_cfg = this->ike_sa->get_ike_cfg(this->ike_sa); + + /* destination is always set */ + host = message->get_destination(message); + notify = build_natd_payload(this, NAT_DETECTION_DESTINATION_IP, host); + if (notify) + { + message->add_payload(message, (payload_t*)notify); + } + + /* source may be any, we have 3 possibilities to get our source address: + * 1. It is defined in the config => use the one of the IKE_SA + * 2. We do a routing lookup in the kernel interface + * 3. Include all possbile addresses + */ + host = message->get_source(message); + if (!host->is_anyaddr(host) || ike_cfg->force_encap(ike_cfg)) + { /* 1. or if we force UDP encap, as it doesn't matter if it's %any */ + notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host); + if (notify) + { + message->add_payload(message, (payload_t*)notify); + } + } + else + { + host = hydra->kernel_interface->get_source_addr(hydra->kernel_interface, + this->ike_sa->get_other_host(this->ike_sa), NULL); + if (host) + { /* 2. */ + host->set_port(host, ike_cfg->get_my_port(ike_cfg)); + notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host); + if (notify) + { + message->add_payload(message, (payload_t*)notify); + } + host->destroy(host); + } + else + { /* 3. */ + enumerator = hydra->kernel_interface->create_address_enumerator( + hydra->kernel_interface, ADDR_TYPE_REGULAR); + while (enumerator->enumerate(enumerator, (void**)&host)) + { + /* apply port 500 to host, but work on a copy */ + host = host->clone(host); + host->set_port(host, ike_cfg->get_my_port(ike_cfg)); + notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host); + host->destroy(host); + if (notify) + { + message->add_payload(message, (payload_t*)notify); + } + } + enumerator->destroy(enumerator); + } + } + return NEED_MORE; +} + +METHOD(task_t, build_r, status_t, + private_ike_natd_t *this, message_t *message) +{ + notify_payload_t *notify; + host_t *me, *other; + + /* only add notifies on successful responses. */ + if (message->get_exchange_type(message) == IKE_SA_INIT && + message->get_payload(message, SECURITY_ASSOCIATION) == NULL) + { + return SUCCESS; + } + + if (this->src_seen && this->dst_seen) + { + if (this->hasher == NULL) + { + DBG1(DBG_IKE, "unable to build NATD payloads, SHA1 not supported"); + return SUCCESS; + } + + /* initiator seems to support NAT detection, add response */ + me = message->get_source(message); + notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, me); + if (notify) + { + message->add_payload(message, (payload_t*)notify); + } + other = message->get_destination(message); + notify = build_natd_payload(this, NAT_DETECTION_DESTINATION_IP, other); + if (notify) + { + message->add_payload(message, (payload_t*)notify); + } + } + return SUCCESS; +} + +METHOD(task_t, process_r, status_t, + private_ike_natd_t *this, message_t *message) +{ + process_payloads(this, message); + + return NEED_MORE; +} + +METHOD(task_t, get_type, task_type_t, + private_ike_natd_t *this) +{ + return TASK_IKE_NATD; +} + +METHOD(task_t, migrate, void, + private_ike_natd_t *this, ike_sa_t *ike_sa) +{ + this->ike_sa = ike_sa; + this->src_seen = FALSE; + this->dst_seen = FALSE; + this->src_matched = FALSE; + this->dst_matched = FALSE; + this->mapping_changed = FALSE; +} + +METHOD(task_t, destroy, void, + private_ike_natd_t *this) +{ + DESTROY_IF(this->hasher); + free(this); +} + +METHOD(ike_natd_t, has_mapping_changed, bool, + private_ike_natd_t *this) +{ + return this->mapping_changed; +} + +/* + * Described in header. + */ +ike_natd_t *ike_natd_create(ike_sa_t *ike_sa, bool initiator) +{ + private_ike_natd_t *this; + + INIT(this, + .public = { + .task = { + .get_type = _get_type, + .migrate = _migrate, + .destroy = _destroy, + }, + .has_mapping_changed = _has_mapping_changed, + }, + .ike_sa = ike_sa, + .initiator = initiator, + .hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1), + ); + + if (initiator) + { + this->public.task.build = _build_i; + this->public.task.process = _process_i; + } + else + { + this->public.task.build = _build_r; + this->public.task.process = _process_r; + } + + return &this->public; +} |