diff options
Diffstat (limited to 'src/or/hs_circuit.c')
| -rw-r--r-- | src/or/hs_circuit.c | 1250 |
1 files changed, 1250 insertions, 0 deletions
diff --git a/src/or/hs_circuit.c b/src/or/hs_circuit.c new file mode 100644 index 0000000000..d911f5fde4 --- /dev/null +++ b/src/or/hs_circuit.c @@ -0,0 +1,1250 @@ +/* Copyright (c) 2017, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file hs_circuit.c + **/ + +#define HS_CIRCUIT_PRIVATE + +#include "or.h" +#include "circpathbias.h" +#include "circuitbuild.h" +#include "circuitlist.h" +#include "circuituse.h" +#include "config.h" +#include "crypto_rand.h" +#include "crypto_util.h" +#include "nodelist.h" +#include "policies.h" +#include "relay.h" +#include "rendservice.h" +#include "rephist.h" +#include "router.h" + +#include "hs_cell.h" +#include "hs_ident.h" +#include "hs_ntor.h" +#include "hs_service.h" +#include "hs_circuit.h" + +/* Trunnel. */ +#include "ed25519_cert.h" +#include "hs/cell_common.h" +#include "hs/cell_establish_intro.h" + +/* A circuit is about to become an e2e rendezvous circuit. Check + * <b>circ_purpose</b> and ensure that it's properly set. Return true iff + * circuit purpose is properly set, otherwise return false. */ +static int +circuit_purpose_is_correct_for_rend(unsigned int circ_purpose, + int is_service_side) +{ + if (is_service_side) { + if (circ_purpose != CIRCUIT_PURPOSE_S_CONNECT_REND) { + log_warn(LD_BUG, + "HS e2e circuit setup with wrong purpose (%d)", circ_purpose); + return 0; + } + } + + if (!is_service_side) { + if (circ_purpose != CIRCUIT_PURPOSE_C_REND_READY && + circ_purpose != CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED) { + log_warn(LD_BUG, + "Client e2e circuit setup with wrong purpose (%d)", circ_purpose); + return 0; + } + } + + return 1; +} + +/* Create and return a crypt path for the final hop of a v3 prop224 rendezvous + * circuit. Initialize the crypt path crypto using the output material from the + * ntor key exchange at <b>ntor_key_seed</b>. + * + * If <b>is_service_side</b> is set, we are the hidden service and the final + * hop of the rendezvous circuit is the client on the other side. */ +static crypt_path_t * +create_rend_cpath(const uint8_t *ntor_key_seed, size_t seed_len, + int is_service_side) +{ + uint8_t keys[HS_NTOR_KEY_EXPANSION_KDF_OUT_LEN]; + crypt_path_t *cpath = NULL; + + /* Do the key expansion */ + if (hs_ntor_circuit_key_expansion(ntor_key_seed, seed_len, + keys, sizeof(keys)) < 0) { + goto err; + } + + /* Setup the cpath */ + cpath = tor_malloc_zero(sizeof(crypt_path_t)); + cpath->magic = CRYPT_PATH_MAGIC; + + if (circuit_init_cpath_crypto(cpath, (char*)keys, sizeof(keys), + is_service_side, 1) < 0) { + tor_free(cpath); + goto err; + } + + err: + memwipe(keys, 0, sizeof(keys)); + return cpath; +} + +/* We are a v2 legacy HS client: Create and return a crypt path for the hidden + * service on the other side of the rendezvous circuit <b>circ</b>. Initialize + * the crypt path crypto using the body of the RENDEZVOUS1 cell at + * <b>rend_cell_body</b> (which must be at least DH_KEY_LEN+DIGEST_LEN bytes). + */ +static crypt_path_t * +create_rend_cpath_legacy(origin_circuit_t *circ, const uint8_t *rend_cell_body) +{ + crypt_path_t *hop = NULL; + char keys[DIGEST_LEN+CPATH_KEY_MATERIAL_LEN]; + + /* first DH_KEY_LEN bytes are g^y from the service. Finish the dh + * handshake...*/ + tor_assert(circ->build_state); + tor_assert(circ->build_state->pending_final_cpath); + hop = circ->build_state->pending_final_cpath; + + tor_assert(hop->rend_dh_handshake_state); + if (crypto_dh_compute_secret(LOG_PROTOCOL_WARN, hop->rend_dh_handshake_state, + (char*)rend_cell_body, DH_KEY_LEN, + keys, DIGEST_LEN+CPATH_KEY_MATERIAL_LEN)<0) { + log_warn(LD_GENERAL, "Couldn't complete DH handshake."); + goto err; + } + /* ... and set up cpath. */ + if (circuit_init_cpath_crypto(hop, + keys+DIGEST_LEN, sizeof(keys)-DIGEST_LEN, + 0, 0) < 0) + goto err; + + /* Check whether the digest is right... */ + if (tor_memneq(keys, rend_cell_body+DH_KEY_LEN, DIGEST_LEN)) { + log_warn(LD_PROTOCOL, "Incorrect digest of key material."); + goto err; + } + + /* clean up the crypto stuff we just made */ + crypto_dh_free(hop->rend_dh_handshake_state); + hop->rend_dh_handshake_state = NULL; + + goto done; + + err: + hop = NULL; + + done: + memwipe(keys, 0, sizeof(keys)); + return hop; +} + +/* Append the final <b>hop</b> to the cpath of the rend <b>circ</b>, and mark + * <b>circ</b> ready for use to transfer HS relay cells. */ +static void +finalize_rend_circuit(origin_circuit_t *circ, crypt_path_t *hop, + int is_service_side) +{ + tor_assert(circ); + tor_assert(hop); + + /* Notify the circuit state machine that we are splicing this circuit */ + int new_circ_purpose = is_service_side ? + CIRCUIT_PURPOSE_S_REND_JOINED : CIRCUIT_PURPOSE_C_REND_JOINED; + circuit_change_purpose(TO_CIRCUIT(circ), new_circ_purpose); + + /* All is well. Extend the circuit. */ + hop->state = CPATH_STATE_OPEN; + /* Set the windows to default. */ + hop->package_window = circuit_initial_package_window(); + hop->deliver_window = CIRCWINDOW_START; + + /* Now that this circuit has finished connecting to its destination, + * make sure circuit_get_open_circ_or_launch is willing to return it + * so we can actually use it. */ + circ->hs_circ_has_timed_out = 0; + + /* Append the hop to the cpath of this circuit */ + onion_append_to_cpath(&circ->cpath, hop); + + /* In legacy code, 'pending_final_cpath' points to the final hop we just + * appended to the cpath. We set the original pointer to NULL so that we + * don't double free it. */ + if (circ->build_state) { + circ->build_state->pending_final_cpath = NULL; + } + + /* Finally, mark circuit as ready to be used for client streams */ + if (!is_service_side) { + circuit_try_attaching_streams(circ); + } +} + +/* For a given circuit and a service introduction point object, register the + * intro circuit to the circuitmap. This supports legacy intro point. */ +static void +register_intro_circ(const hs_service_intro_point_t *ip, + origin_circuit_t *circ) +{ + tor_assert(ip); + tor_assert(circ); + + if (ip->base.is_only_legacy) { + hs_circuitmap_register_intro_circ_v2_service_side(circ, + ip->legacy_key_digest); + } else { + hs_circuitmap_register_intro_circ_v3_service_side(circ, + &ip->auth_key_kp.pubkey); + } +} + +/* Return the number of opened introduction circuit for the given circuit that + * is matching its identity key. */ +static unsigned int +count_opened_desc_intro_point_circuits(const hs_service_t *service, + const hs_service_descriptor_t *desc) +{ + unsigned int count = 0; + + tor_assert(service); + tor_assert(desc); + + DIGEST256MAP_FOREACH(desc->intro_points.map, key, + const hs_service_intro_point_t *, ip) { + const circuit_t *circ; + const origin_circuit_t *ocirc = hs_circ_service_get_intro_circ(ip); + if (ocirc == NULL) { + continue; + } + circ = TO_CIRCUIT(ocirc); + tor_assert(circ->purpose == CIRCUIT_PURPOSE_S_ESTABLISH_INTRO || + circ->purpose == CIRCUIT_PURPOSE_S_INTRO); + /* Having a circuit not for the requested service is really bad. */ + tor_assert(ed25519_pubkey_eq(&service->keys.identity_pk, + ô->hs_ident->identity_pk)); + /* Only count opened circuit and skip circuit that will be closed. */ + if (!circ->marked_for_close && circ->state == CIRCUIT_STATE_OPEN) { + count++; + } + } DIGEST256MAP_FOREACH_END; + return count; +} + +/* From a given service, rendezvous cookie and handshake info, create a + * rendezvous point circuit identifier. This can't fail. */ +STATIC hs_ident_circuit_t * +create_rp_circuit_identifier(const hs_service_t *service, + const uint8_t *rendezvous_cookie, + const curve25519_public_key_t *server_pk, + const hs_ntor_rend_cell_keys_t *keys) +{ + hs_ident_circuit_t *ident; + uint8_t handshake_info[CURVE25519_PUBKEY_LEN + DIGEST256_LEN]; + + tor_assert(service); + tor_assert(rendezvous_cookie); + tor_assert(server_pk); + tor_assert(keys); + + ident = hs_ident_circuit_new(&service->keys.identity_pk, + HS_IDENT_CIRCUIT_RENDEZVOUS); + /* Copy the RENDEZVOUS_COOKIE which is the unique identifier. */ + memcpy(ident->rendezvous_cookie, rendezvous_cookie, + sizeof(ident->rendezvous_cookie)); + /* Build the HANDSHAKE_INFO which looks like this: + * SERVER_PK [32 bytes] + * AUTH_INPUT_MAC [32 bytes] + */ + memcpy(handshake_info, server_pk->public_key, CURVE25519_PUBKEY_LEN); + memcpy(handshake_info + CURVE25519_PUBKEY_LEN, keys->rend_cell_auth_mac, + DIGEST256_LEN); + tor_assert(sizeof(ident->rendezvous_handshake_info) == + sizeof(handshake_info)); + memcpy(ident->rendezvous_handshake_info, handshake_info, + sizeof(ident->rendezvous_handshake_info)); + /* Finally copy the NTOR_KEY_SEED for e2e encryption on the circuit. */ + tor_assert(sizeof(ident->rendezvous_ntor_key_seed) == + sizeof(keys->ntor_key_seed)); + memcpy(ident->rendezvous_ntor_key_seed, keys->ntor_key_seed, + sizeof(ident->rendezvous_ntor_key_seed)); + return ident; +} + +/* From a given service and service intro point, create an introduction point + * circuit identifier. This can't fail. */ +static hs_ident_circuit_t * +create_intro_circuit_identifier(const hs_service_t *service, + const hs_service_intro_point_t *ip) +{ + hs_ident_circuit_t *ident; + + tor_assert(service); + tor_assert(ip); + + ident = hs_ident_circuit_new(&service->keys.identity_pk, + HS_IDENT_CIRCUIT_INTRO); + ed25519_pubkey_copy(&ident->intro_auth_pk, &ip->auth_key_kp.pubkey); + + return ident; +} + +/* For a given introduction point and an introduction circuit, send the + * ESTABLISH_INTRO cell. The service object is used for logging. This can fail + * and if so, the circuit is closed and the intro point object is flagged + * that the circuit is not established anymore which is important for the + * retry mechanism. */ +static void +send_establish_intro(const hs_service_t *service, + hs_service_intro_point_t *ip, origin_circuit_t *circ) +{ + ssize_t cell_len; + uint8_t payload[RELAY_PAYLOAD_SIZE]; + + tor_assert(service); + tor_assert(ip); + tor_assert(circ); + + /* Encode establish intro cell. */ + cell_len = hs_cell_build_establish_intro(circ->cpath->prev->rend_circ_nonce, + ip, payload); + if (cell_len < 0) { + log_warn(LD_REND, "Unable to encode ESTABLISH_INTRO cell for service %s " + "on circuit %u. Closing circuit.", + safe_str_client(service->onion_address), + TO_CIRCUIT(circ)->n_circ_id); + goto err; + } + + /* Send the cell on the circuit. */ + if (relay_send_command_from_edge(CONTROL_CELL_ID, TO_CIRCUIT(circ), + RELAY_COMMAND_ESTABLISH_INTRO, + (char *) payload, cell_len, + circ->cpath->prev) < 0) { + log_info(LD_REND, "Unable to send ESTABLISH_INTRO cell for service %s " + "on circuit %u.", + safe_str_client(service->onion_address), + TO_CIRCUIT(circ)->n_circ_id); + /* On error, the circuit has been closed. */ + goto done; + } + + /* Record the attempt to use this circuit. */ + pathbias_count_use_attempt(circ); + goto done; + + err: + circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL); + done: + memwipe(payload, 0, sizeof(payload)); +} + +/* Return a string constant describing the anonymity of service. */ +static const char * +get_service_anonymity_string(const hs_service_t *service) +{ + if (service->config.is_single_onion) { + return "single onion"; + } else { + return "hidden"; + } +} + +/* For a given service, the ntor onion key and a rendezvous cookie, launch a + * circuit to the rendezvous point specified by the link specifiers. On + * success, a circuit identifier is attached to the circuit with the needed + * data. This function will try to open a circuit for a maximum value of + * MAX_REND_FAILURES then it will give up. */ +static void +launch_rendezvous_point_circuit(const hs_service_t *service, + const hs_service_intro_point_t *ip, + const hs_cell_introduce2_data_t *data) +{ + int circ_needs_uptime; + time_t now = time(NULL); + extend_info_t *info = NULL; + origin_circuit_t *circ; + + tor_assert(service); + tor_assert(ip); + tor_assert(data); + + circ_needs_uptime = hs_service_requires_uptime_circ(service->config.ports); + + /* Get the extend info data structure for the chosen rendezvous point + * specified by the given link specifiers. */ + info = hs_get_extend_info_from_lspecs(data->link_specifiers, + &data->onion_pk, + service->config.is_single_onion); + if (info == NULL) { + /* We are done here, we can't extend to the rendezvous point. + * If you're running an IPv6-only v3 single onion service on 0.3.2 or with + * 0.3.2 clients, and somehow disable the option check, it will fail here. + */ + log_fn(LOG_PROTOCOL_WARN, LD_REND, + "Not enough info to open a circuit to a rendezvous point for " + "%s service %s.", + get_service_anonymity_string(service), + safe_str_client(service->onion_address)); + goto end; + } + + for (int i = 0; i < MAX_REND_FAILURES; i++) { + int circ_flags = CIRCLAUNCH_NEED_CAPACITY | CIRCLAUNCH_IS_INTERNAL; + if (circ_needs_uptime) { + circ_flags |= CIRCLAUNCH_NEED_UPTIME; + } + /* Firewall and policies are checked when getting the extend info. */ + if (service->config.is_single_onion) { + circ_flags |= CIRCLAUNCH_ONEHOP_TUNNEL; + } + + circ = circuit_launch_by_extend_info(CIRCUIT_PURPOSE_S_CONNECT_REND, info, + circ_flags); + if (circ != NULL) { + /* Stop retrying, we have a circuit! */ + break; + } + } + if (circ == NULL) { + log_warn(LD_REND, "Giving up on launching a rendezvous circuit to %s " + "for %s service %s", + safe_str_client(extend_info_describe(info)), + get_service_anonymity_string(service), + safe_str_client(service->onion_address)); + goto end; + } + log_info(LD_REND, "Rendezvous circuit launched to %s with cookie %s " + "for %s service %s", + safe_str_client(extend_info_describe(info)), + safe_str_client(hex_str((const char *) data->rendezvous_cookie, + REND_COOKIE_LEN)), + get_service_anonymity_string(service), + safe_str_client(service->onion_address)); + tor_assert(circ->build_state); + /* Rendezvous circuit have a specific timeout for the time spent on trying + * to connect to the rendezvous point. */ + circ->build_state->expiry_time = now + MAX_REND_TIMEOUT; + + /* Create circuit identifier and key material. */ + { + hs_ntor_rend_cell_keys_t keys; + curve25519_keypair_t ephemeral_kp; + /* No need for extra strong, this is only for this circuit life time. This + * key will be used for the RENDEZVOUS1 cell that will be sent on the + * circuit once opened. */ + curve25519_keypair_generate(&ephemeral_kp, 0); + if (hs_ntor_service_get_rendezvous1_keys(&ip->auth_key_kp.pubkey, + &ip->enc_key_kp, + &ephemeral_kp, &data->client_pk, + &keys) < 0) { + /* This should not really happened but just in case, don't make tor + * freak out, close the circuit and move on. */ + log_info(LD_REND, "Unable to get RENDEZVOUS1 key material for " + "service %s", + safe_str_client(service->onion_address)); + circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL); + goto end; + } + circ->hs_ident = create_rp_circuit_identifier(service, + data->rendezvous_cookie, + &ephemeral_kp.pubkey, &keys); + memwipe(&ephemeral_kp, 0, sizeof(ephemeral_kp)); + memwipe(&keys, 0, sizeof(keys)); + tor_assert(circ->hs_ident); + } + + end: + extend_info_free(info); +} + +/* Return true iff the given service rendezvous circuit circ is allowed for a + * relaunch to the rendezvous point. */ +static int +can_relaunch_service_rendezvous_point(const origin_circuit_t *circ) +{ + tor_assert(circ); + /* This is initialized when allocating an origin circuit. */ + tor_assert(circ->build_state); + tor_assert(TO_CIRCUIT(circ)->purpose == CIRCUIT_PURPOSE_S_CONNECT_REND); + + /* XXX: Retrying under certain condition. This is related to #22455. */ + + /* Avoid to relaunch twice a circuit to the same rendezvous point at the + * same time. */ + if (circ->hs_service_side_rend_circ_has_been_relaunched) { + log_info(LD_REND, "Rendezvous circuit to %s has already been retried. " + "Skipping retry.", + safe_str_client( + extend_info_describe(circ->build_state->chosen_exit))); + goto disallow; + } + + /* We check failure_count >= hs_get_service_max_rend_failures()-1 below, and + * the -1 is because we increment the failure count for our current failure + * *after* this clause. */ + int max_rend_failures = hs_get_service_max_rend_failures() - 1; + + /* A failure count that has reached maximum allowed or circuit that expired, + * we skip relaunching. */ + if (circ->build_state->failure_count > max_rend_failures || + circ->build_state->expiry_time <= time(NULL)) { + log_info(LD_REND, "Attempt to build a rendezvous circuit to %s has " + "failed with %d attempts and expiry time %ld. " + "Giving up building.", + safe_str_client( + extend_info_describe(circ->build_state->chosen_exit)), + circ->build_state->failure_count, + (long int) circ->build_state->expiry_time); + goto disallow; + } + + /* Allowed to relaunch. */ + return 1; + disallow: + return 0; +} + +/* Retry the rendezvous point of circ by launching a new circuit to it. */ +static void +retry_service_rendezvous_point(const origin_circuit_t *circ) +{ + int flags = 0; + origin_circuit_t *new_circ; + cpath_build_state_t *bstate; + + tor_assert(circ); + /* This is initialized when allocating an origin circuit. */ + tor_assert(circ->build_state); + tor_assert(TO_CIRCUIT(circ)->purpose == CIRCUIT_PURPOSE_S_CONNECT_REND); + + /* Ease our life. */ + bstate = circ->build_state; + + log_info(LD_REND, "Retrying rendezvous point circuit to %s", + safe_str_client(extend_info_describe(bstate->chosen_exit))); + + /* Get the current build state flags for the next circuit. */ + flags |= (bstate->need_uptime) ? CIRCLAUNCH_NEED_UPTIME : 0; + flags |= (bstate->need_capacity) ? CIRCLAUNCH_NEED_CAPACITY : 0; + flags |= (bstate->is_internal) ? CIRCLAUNCH_IS_INTERNAL : 0; + + /* We do NOT add the onehop tunnel flag even though it might be a single + * onion service. The reason is that if we failed once to connect to the RP + * with a direct connection, we consider that chances are that we will fail + * again so try a 3-hop circuit and hope for the best. Because the service + * has no anonymity (single onion), this change of behavior won't affect + * security directly. */ + + new_circ = circuit_launch_by_extend_info(CIRCUIT_PURPOSE_S_CONNECT_REND, + bstate->chosen_exit, flags); + if (new_circ == NULL) { + log_warn(LD_REND, "Failed to launch rendezvous circuit to %s", + safe_str_client(extend_info_describe(bstate->chosen_exit))); + goto done; + } + + /* Transfer build state information to the new circuit state in part to + * catch any other failures. */ + new_circ->build_state->failure_count = bstate->failure_count+1; + new_circ->build_state->expiry_time = bstate->expiry_time; + new_circ->hs_ident = hs_ident_circuit_dup(circ->hs_ident); + + done: + return; +} + +/* Add all possible link specifiers in node to lspecs: + * - legacy ID is mandatory thus MUST be present in node; + * - include ed25519 link specifier if present in the node, and the node + * supports ed25519 link authentication, even if its link versions are not + * compatible with us; + * - include IPv4 link specifier, if the primary address is not IPv4, log a + * BUG() warning, and return an empty smartlist; + * - include IPv6 link specifier if present in the node. */ +static void +get_lspecs_from_node(const node_t *node, smartlist_t *lspecs) +{ + link_specifier_t *ls; + tor_addr_port_t ap; + + tor_assert(node); + tor_assert(lspecs); + + /* Get the relay's IPv4 address. */ + node_get_prim_orport(node, &ap); + + /* We expect the node's primary address to be a valid IPv4 address. + * This conforms to the protocol, which requires either an IPv4 or IPv6 + * address (or both). */ + if (BUG(!tor_addr_is_v4(&ap.addr)) || + BUG(!tor_addr_port_is_valid_ap(&ap, 0))) { + return; + } + + ls = link_specifier_new(); + link_specifier_set_ls_type(ls, LS_IPV4); + link_specifier_set_un_ipv4_addr(ls, tor_addr_to_ipv4h(&ap.addr)); + link_specifier_set_un_ipv4_port(ls, ap.port); + /* Four bytes IPv4 and two bytes port. */ + link_specifier_set_ls_len(ls, sizeof(ap.addr.addr.in_addr) + + sizeof(ap.port)); + smartlist_add(lspecs, ls); + + /* Legacy ID is mandatory and will always be present in node. */ + ls = link_specifier_new(); + link_specifier_set_ls_type(ls, LS_LEGACY_ID); + memcpy(link_specifier_getarray_un_legacy_id(ls), node->identity, + link_specifier_getlen_un_legacy_id(ls)); + link_specifier_set_ls_len(ls, link_specifier_getlen_un_legacy_id(ls)); + smartlist_add(lspecs, ls); + + /* ed25519 ID is only included if the node has it, and the node declares a + protocol version that supports ed25519 link authentication, even if that + link version is not compatible with us. (We are sending the ed25519 key + to another tor, which may support different link versions.) */ + if (!ed25519_public_key_is_zero(&node->ed25519_id) && + node_supports_ed25519_link_authentication(node, 0)) { + ls = link_specifier_new(); + link_specifier_set_ls_type(ls, LS_ED25519_ID); + memcpy(link_specifier_getarray_un_ed25519_id(ls), &node->ed25519_id, + link_specifier_getlen_un_ed25519_id(ls)); + link_specifier_set_ls_len(ls, link_specifier_getlen_un_ed25519_id(ls)); + smartlist_add(lspecs, ls); + } + + /* Check for IPv6. If so, include it as well. */ + if (node_has_ipv6_orport(node)) { + ls = link_specifier_new(); + node_get_pref_ipv6_orport(node, &ap); + link_specifier_set_ls_type(ls, LS_IPV6); + size_t addr_len = link_specifier_getlen_un_ipv6_addr(ls); + const uint8_t *in6_addr = tor_addr_to_in6_addr8(&ap.addr); + uint8_t *ipv6_array = link_specifier_getarray_un_ipv6_addr(ls); + memcpy(ipv6_array, in6_addr, addr_len); + link_specifier_set_un_ipv6_port(ls, ap.port); + /* Sixteen bytes IPv6 and two bytes port. */ + link_specifier_set_ls_len(ls, addr_len + sizeof(ap.port)); + smartlist_add(lspecs, ls); + } +} + +/* Using the given descriptor intro point ip, the node of the + * rendezvous point rp_node and the service's subcredential, populate the + * already allocated intro1_data object with the needed key material and link + * specifiers. + * + * If rp_node has an invalid primary address, intro1_data->link_specifiers + * will be an empty list. Otherwise, this function can't fail. The ip + * MUST be a valid object containing the needed keys and authentication + * method. */ +static void +setup_introduce1_data(const hs_desc_intro_point_t *ip, + const node_t *rp_node, + const uint8_t *subcredential, + hs_cell_introduce1_data_t *intro1_data) +{ + smartlist_t *rp_lspecs; + + tor_assert(ip); + tor_assert(rp_node); + tor_assert(subcredential); + tor_assert(intro1_data); + + /* Build the link specifiers from the extend information of the rendezvous + * circuit that we've picked previously. */ + rp_lspecs = smartlist_new(); + get_lspecs_from_node(rp_node, rp_lspecs); + + /* Populate the introduce1 data object. */ + memset(intro1_data, 0, sizeof(hs_cell_introduce1_data_t)); + if (ip->legacy.key != NULL) { + intro1_data->is_legacy = 1; + intro1_data->legacy_key = ip->legacy.key; + } + intro1_data->auth_pk = &ip->auth_key_cert->signed_key; + intro1_data->enc_pk = &ip->enc_key; + intro1_data->subcredential = subcredential; + intro1_data->onion_pk = node_get_curve25519_onion_key(rp_node); + intro1_data->link_specifiers = rp_lspecs; +} + +/* ========== */ +/* Public API */ +/* ========== */ + +/* Return an introduction point circuit matching the given intro point object. + * NULL is returned is no such circuit can be found. */ +origin_circuit_t * +hs_circ_service_get_intro_circ(const hs_service_intro_point_t *ip) +{ + tor_assert(ip); + + if (ip->base.is_only_legacy) { + return hs_circuitmap_get_intro_circ_v2_service_side(ip->legacy_key_digest); + } else { + return hs_circuitmap_get_intro_circ_v3_service_side( + &ip->auth_key_kp.pubkey); + } +} + +/* Called when we fail building a rendezvous circuit at some point other than + * the last hop: launches a new circuit to the same rendezvous point. This + * supports legacy service. + * + * We currently relaunch connections to rendezvous points if: + * - A rendezvous circuit timed out before connecting to RP. + * - The rendezvous circuit failed to connect to the RP. + * + * We avoid relaunching a connection to this rendezvous point if: + * - We have already tried MAX_REND_FAILURES times to connect to this RP, + * - We've been trying to connect to this RP for more than MAX_REND_TIMEOUT + * seconds, or + * - We've already retried this specific rendezvous circuit. + */ +void +hs_circ_retry_service_rendezvous_point(origin_circuit_t *circ) +{ + tor_assert(circ); + tor_assert(TO_CIRCUIT(circ)->purpose == CIRCUIT_PURPOSE_S_CONNECT_REND); + + /* Check if we are allowed to relaunch to the rendezvous point of circ. */ + if (!can_relaunch_service_rendezvous_point(circ)) { + goto done; + } + + /* Flag the circuit that we are relaunching, to avoid to relaunch twice a + * circuit to the same rendezvous point at the same time. */ + circ->hs_service_side_rend_circ_has_been_relaunched = 1; + + /* Legacy services don't have a hidden service ident. */ + if (circ->hs_ident) { + retry_service_rendezvous_point(circ); + } else { + rend_service_relaunch_rendezvous(circ); + } + + done: + return; +} + +/* For a given service and a service intro point, launch a circuit to the + * extend info ei. If the service is a single onion, a one-hop circuit will be + * requested. Return 0 if the circuit was successfully launched and tagged + * with the correct identifier. On error, a negative value is returned. */ +int +hs_circ_launch_intro_point(hs_service_t *service, + const hs_service_intro_point_t *ip, + extend_info_t *ei) +{ + /* Standard flags for introduction circuit. */ + int ret = -1, circ_flags = CIRCLAUNCH_NEED_UPTIME | CIRCLAUNCH_IS_INTERNAL; + origin_circuit_t *circ; + + tor_assert(service); + tor_assert(ip); + tor_assert(ei); + + /* Update circuit flags in case of a single onion service that requires a + * direct connection. */ + if (service->config.is_single_onion) { + circ_flags |= CIRCLAUNCH_ONEHOP_TUNNEL; + } + + log_info(LD_REND, "Launching a circuit to intro point %s for service %s.", + safe_str_client(extend_info_describe(ei)), + safe_str_client(service->onion_address)); + + /* Note down the launch for the retry period. Even if the circuit fails to + * be launched, we still want to respect the retry period to avoid stress on + * the circuit subsystem. */ + service->state.num_intro_circ_launched++; + circ = circuit_launch_by_extend_info(CIRCUIT_PURPOSE_S_ESTABLISH_INTRO, + ei, circ_flags); + if (circ == NULL) { + goto end; + } + + /* Setup the circuit identifier and attach it to it. */ + circ->hs_ident = create_intro_circuit_identifier(service, ip); + tor_assert(circ->hs_ident); + /* Register circuit in the global circuitmap. */ + register_intro_circ(ip, circ); + + /* Success. */ + ret = 0; + end: + return ret; +} + +/* Called when a service introduction point circuit is done building. Given + * the service and intro point object, this function will send the + * ESTABLISH_INTRO cell on the circuit. Return 0 on success. Return 1 if the + * circuit has been repurposed to General because we already have too many + * opened. */ +int +hs_circ_service_intro_has_opened(hs_service_t *service, + hs_service_intro_point_t *ip, + const hs_service_descriptor_t *desc, + origin_circuit_t *circ) +{ + int ret = 0; + unsigned int num_intro_circ, num_needed_circ; + + tor_assert(service); + tor_assert(ip); + tor_assert(desc); + tor_assert(circ); + + /* Cound opened circuits that have sent ESTABLISH_INTRO cells or are already + * established introduction circuits */ + num_intro_circ = count_opened_desc_intro_point_circuits(service, desc); + num_needed_circ = service->config.num_intro_points; + if (num_intro_circ > num_needed_circ) { + /* There are too many opened valid intro circuit for what the service + * needs so repurpose this one. */ + + /* XXX: Legacy code checks options->ExcludeNodes and if not NULL it just + * closes the circuit. I have NO idea why it does that so it hasn't been + * added here. I can only assume in case our ExcludeNodes list changes but + * in that case, all circuit are flagged unusable (config.c). --dgoulet */ + + log_info(LD_CIRC | LD_REND, "Introduction circuit just opened but we " + "have enough for service %s. Repurposing " + "it to general and leaving internal.", + safe_str_client(service->onion_address)); + tor_assert(circ->build_state->is_internal); + /* Remove it from the circuitmap. */ + hs_circuitmap_remove_circuit(TO_CIRCUIT(circ)); + /* Cleaning up the hidden service identifier and repurpose. */ + hs_ident_circuit_free(circ->hs_ident); + circ->hs_ident = NULL; + if (circuit_should_use_vanguards(TO_CIRCUIT(circ)->purpose)) + circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_HS_VANGUARDS); + else + circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_C_GENERAL); + + /* Inform that this circuit just opened for this new purpose. */ + circuit_has_opened(circ); + /* This return value indicate to the caller that the IP object should be + * removed from the service because it's corresponding circuit has just + * been repurposed. */ + ret = 1; + goto done; + } + + log_info(LD_REND, "Introduction circuit %u established for service %s.", + TO_CIRCUIT(circ)->n_circ_id, + safe_str_client(service->onion_address)); + circuit_log_path(LOG_INFO, LD_REND, circ); + + /* Time to send an ESTABLISH_INTRO cell on this circuit. On error, this call + * makes sure the circuit gets closed. */ + send_establish_intro(service, ip, circ); + + done: + return ret; +} + +/* Called when a service rendezvous point circuit is done building. Given the + * service and the circuit, this function will send a RENDEZVOUS1 cell on the + * circuit using the information in the circuit identifier. If the cell can't + * be sent, the circuit is closed. */ +void +hs_circ_service_rp_has_opened(const hs_service_t *service, + origin_circuit_t *circ) +{ + size_t payload_len; + uint8_t payload[RELAY_PAYLOAD_SIZE] = {0}; + + tor_assert(service); + tor_assert(circ); + tor_assert(circ->hs_ident); + + /* Some useful logging. */ + log_info(LD_REND, "Rendezvous circuit %u has opened with cookie %s " + "for service %s", + TO_CIRCUIT(circ)->n_circ_id, + hex_str((const char *) circ->hs_ident->rendezvous_cookie, + REND_COOKIE_LEN), + safe_str_client(service->onion_address)); + circuit_log_path(LOG_INFO, LD_REND, circ); + + /* This can't fail. */ + payload_len = hs_cell_build_rendezvous1( + circ->hs_ident->rendezvous_cookie, + sizeof(circ->hs_ident->rendezvous_cookie), + circ->hs_ident->rendezvous_handshake_info, + sizeof(circ->hs_ident->rendezvous_handshake_info), + payload); + + /* Pad the payload with random bytes so it matches the size of a legacy cell + * which is normally always bigger. Also, the size of a legacy cell is + * always smaller than the RELAY_PAYLOAD_SIZE so this is safe. */ + if (payload_len < HS_LEGACY_RENDEZVOUS_CELL_SIZE) { + crypto_rand((char *) payload + payload_len, + HS_LEGACY_RENDEZVOUS_CELL_SIZE - payload_len); + payload_len = HS_LEGACY_RENDEZVOUS_CELL_SIZE; + } + + if (relay_send_command_from_edge(CONTROL_CELL_ID, TO_CIRCUIT(circ), + RELAY_COMMAND_RENDEZVOUS1, + (const char *) payload, payload_len, + circ->cpath->prev) < 0) { + /* On error, circuit is closed. */ + log_warn(LD_REND, "Unable to send RENDEZVOUS1 cell on circuit %u " + "for service %s", + TO_CIRCUIT(circ)->n_circ_id, + safe_str_client(service->onion_address)); + goto done; + } + + /* Setup end-to-end rendezvous circuit between the client and us. */ + if (hs_circuit_setup_e2e_rend_circ(circ, + circ->hs_ident->rendezvous_ntor_key_seed, + sizeof(circ->hs_ident->rendezvous_ntor_key_seed), + 1) < 0) { + log_warn(LD_GENERAL, "Failed to setup circ"); + goto done; + } + + done: + memwipe(payload, 0, sizeof(payload)); +} + +/* Circ has been expecting an INTRO_ESTABLISHED cell that just arrived. Handle + * the INTRO_ESTABLISHED cell payload of length payload_len arriving on the + * given introduction circuit circ. The service is only used for logging + * purposes. Return 0 on success else a negative value. */ +int +hs_circ_handle_intro_established(const hs_service_t *service, + const hs_service_intro_point_t *ip, + origin_circuit_t *circ, + const uint8_t *payload, size_t payload_len) +{ + int ret = -1; + + tor_assert(service); + tor_assert(ip); + tor_assert(circ); + tor_assert(payload); + + if (BUG(TO_CIRCUIT(circ)->purpose != CIRCUIT_PURPOSE_S_ESTABLISH_INTRO)) { + goto done; + } + + /* Try to parse the payload into a cell making sure we do actually have a + * valid cell. For a legacy node, it's an empty payload so as long as we + * have the cell, we are good. */ + if (!ip->base.is_only_legacy && + hs_cell_parse_intro_established(payload, payload_len) < 0) { + log_warn(LD_REND, "Unable to parse the INTRO_ESTABLISHED cell on " + "circuit %u for service %s", + TO_CIRCUIT(circ)->n_circ_id, + safe_str_client(service->onion_address)); + goto done; + } + + /* Switch the purpose to a fully working intro point. */ + circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_S_INTRO); + /* Getting a valid INTRODUCE_ESTABLISHED means we've successfully used the + * circuit so update our pathbias subsystem. */ + pathbias_mark_use_success(circ); + /* Success. */ + ret = 0; + + done: + return ret; +} + +/* We just received an INTRODUCE2 cell on the established introduction circuit + * circ. Handle the INTRODUCE2 payload of size payload_len for the given + * circuit and service. This cell is associated with the intro point object ip + * and the subcredential. Return 0 on success else a negative value. */ +int +hs_circ_handle_introduce2(const hs_service_t *service, + const origin_circuit_t *circ, + hs_service_intro_point_t *ip, + const uint8_t *subcredential, + const uint8_t *payload, size_t payload_len) +{ + int ret = -1; + time_t elapsed; + hs_cell_introduce2_data_t data; + + tor_assert(service); + tor_assert(circ); + tor_assert(ip); + tor_assert(subcredential); + tor_assert(payload); + + /* Populate the data structure with everything we need for the cell to be + * parsed, decrypted and key material computed correctly. */ + data.auth_pk = &ip->auth_key_kp.pubkey; + data.enc_kp = &ip->enc_key_kp; + data.subcredential = subcredential; + data.payload = payload; + data.payload_len = payload_len; + data.link_specifiers = smartlist_new(); + data.replay_cache = ip->replay_cache; + + if (hs_cell_parse_introduce2(&data, circ, service) < 0) { + goto done; + } + + /* Check whether we've seen this REND_COOKIE before to detect repeats. */ + if (replaycache_add_test_and_elapsed( + service->state.replay_cache_rend_cookie, + data.rendezvous_cookie, sizeof(data.rendezvous_cookie), + &elapsed)) { + /* A Tor client will send a new INTRODUCE1 cell with the same REND_COOKIE + * as its previous one if its intro circ times out while in state + * CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT. If we received the first + * INTRODUCE1 cell (the intro-point relay converts it into an INTRODUCE2 + * cell), we are already trying to connect to that rend point (and may + * have already succeeded); drop this cell. */ + log_info(LD_REND, "We received an INTRODUCE2 cell with same REND_COOKIE " + "field %ld seconds ago. Dropping cell.", + (long int) elapsed); + goto done; + } + + /* At this point, we just confirmed that the full INTRODUCE2 cell is valid + * so increment our counter that we've seen one on this intro point. */ + ip->introduce2_count++; + + /* Launch rendezvous circuit with the onion key and rend cookie. */ + launch_rendezvous_point_circuit(service, ip, &data); + /* Success. */ + ret = 0; + + done: + SMARTLIST_FOREACH(data.link_specifiers, link_specifier_t *, lspec, + link_specifier_free(lspec)); + smartlist_free(data.link_specifiers); + memwipe(&data, 0, sizeof(data)); + return ret; +} + +/* Circuit <b>circ</b> just finished the rend ntor key exchange. Use the key + * exchange output material at <b>ntor_key_seed</b> and setup <b>circ</b> to + * serve as a rendezvous end-to-end circuit between the client and the + * service. If <b>is_service_side</b> is set, then we are the hidden service + * and the other side is the client. + * + * Return 0 if the operation went well; in case of error return -1. */ +int +hs_circuit_setup_e2e_rend_circ(origin_circuit_t *circ, + const uint8_t *ntor_key_seed, size_t seed_len, + int is_service_side) +{ + if (BUG(!circuit_purpose_is_correct_for_rend(TO_CIRCUIT(circ)->purpose, + is_service_side))) { + return -1; + } + + crypt_path_t *hop = create_rend_cpath(ntor_key_seed, seed_len, + is_service_side); + if (!hop) { + log_warn(LD_REND, "Couldn't get v3 %s cpath!", + is_service_side ? "service-side" : "client-side"); + return -1; + } + + finalize_rend_circuit(circ, hop, is_service_side); + + return 0; +} + +/* We are a v2 legacy HS client and we just received a RENDEZVOUS1 cell + * <b>rend_cell_body</b> on <b>circ</b>. Finish up the DH key exchange and then + * extend the crypt path of <b>circ</b> so that the hidden service is on the + * other side. */ +int +hs_circuit_setup_e2e_rend_circ_legacy_client(origin_circuit_t *circ, + const uint8_t *rend_cell_body) +{ + + if (BUG(!circuit_purpose_is_correct_for_rend( + TO_CIRCUIT(circ)->purpose, 0))) { + return -1; + } + + crypt_path_t *hop = create_rend_cpath_legacy(circ, rend_cell_body); + if (!hop) { + log_warn(LD_GENERAL, "Couldn't get v2 cpath."); + return -1; + } + + finalize_rend_circuit(circ, hop, 0); + + return 0; +} + +/* Given the introduction circuit intro_circ, the rendezvous circuit + * rend_circ, a descriptor intro point object ip and the service's + * subcredential, send an INTRODUCE1 cell on intro_circ. + * + * This will also setup the circuit identifier on rend_circ containing the key + * material for the handshake and e2e encryption. Return 0 on success else + * negative value. Because relay_send_command_from_edge() closes the circuit + * on error, it is possible that intro_circ is closed on error. */ +int +hs_circ_send_introduce1(origin_circuit_t *intro_circ, + origin_circuit_t *rend_circ, + const hs_desc_intro_point_t *ip, + const uint8_t *subcredential) +{ + int ret = -1; + ssize_t payload_len; + uint8_t payload[RELAY_PAYLOAD_SIZE] = {0}; + hs_cell_introduce1_data_t intro1_data; + + tor_assert(intro_circ); + tor_assert(rend_circ); + tor_assert(ip); + tor_assert(subcredential); + + /* It is undefined behavior in hs_cell_introduce1_data_clear() if intro1_data + * has been declared on the stack but not initialized. Here, we set it to 0. + */ + memset(&intro1_data, 0, sizeof(hs_cell_introduce1_data_t)); + + /* This takes various objects in order to populate the introduce1 data + * object which is used to build the content of the cell. */ + const node_t *exit_node = build_state_get_exit_node(rend_circ->build_state); + if (exit_node == NULL) { + log_info(LD_REND, "Unable to get rendezvous point for circuit %u. " + "Failing.", TO_CIRCUIT(intro_circ)->n_circ_id); + goto done; + } + setup_introduce1_data(ip, exit_node, subcredential, &intro1_data); + /* If we didn't get any link specifiers, it's because our node was + * bad. */ + if (BUG(!intro1_data.link_specifiers) || + !smartlist_len(intro1_data.link_specifiers)) { + log_warn(LD_REND, "Unable to get link specifiers for INTRODUCE1 cell on " + "circuit %u.", TO_CIRCUIT(intro_circ)->n_circ_id); + goto done; + } + + /* Final step before we encode a cell, we setup the circuit identifier which + * will generate both the rendezvous cookie and client keypair for this + * connection. Those are put in the ident. */ + intro1_data.rendezvous_cookie = rend_circ->hs_ident->rendezvous_cookie; + intro1_data.client_kp = &rend_circ->hs_ident->rendezvous_client_kp; + + memcpy(intro_circ->hs_ident->rendezvous_cookie, + rend_circ->hs_ident->rendezvous_cookie, + sizeof(intro_circ->hs_ident->rendezvous_cookie)); + + /* From the introduce1 data object, this will encode the INTRODUCE1 cell + * into payload which is then ready to be sent as is. */ + payload_len = hs_cell_build_introduce1(&intro1_data, payload); + if (BUG(payload_len < 0)) { + goto done; + } + + if (relay_send_command_from_edge(CONTROL_CELL_ID, TO_CIRCUIT(intro_circ), + RELAY_COMMAND_INTRODUCE1, + (const char *) payload, payload_len, + intro_circ->cpath->prev) < 0) { + /* On error, circuit is closed. */ + log_warn(LD_REND, "Unable to send INTRODUCE1 cell on circuit %u.", + TO_CIRCUIT(intro_circ)->n_circ_id); + goto done; + } + + /* Success. */ + ret = 0; + goto done; + + done: + hs_cell_introduce1_data_clear(&intro1_data); + memwipe(payload, 0, sizeof(payload)); + return ret; +} + +/* Send an ESTABLISH_RENDEZVOUS cell along the rendezvous circuit circ. On + * success, 0 is returned else -1 and the circuit is marked for close. */ +int +hs_circ_send_establish_rendezvous(origin_circuit_t *circ) +{ + ssize_t cell_len = 0; + uint8_t cell[RELAY_PAYLOAD_SIZE] = {0}; + + tor_assert(circ); + tor_assert(TO_CIRCUIT(circ)->purpose == CIRCUIT_PURPOSE_C_ESTABLISH_REND); + + log_info(LD_REND, "Send an ESTABLISH_RENDEZVOUS cell on circuit %u", + TO_CIRCUIT(circ)->n_circ_id); + + /* Set timestamp_dirty, because circuit_expire_building expects it, + * and the rend cookie also means we've used the circ. */ + TO_CIRCUIT(circ)->timestamp_dirty = time(NULL); + + /* We've attempted to use this circuit. Probe it if we fail */ + pathbias_count_use_attempt(circ); + + /* Generate the RENDEZVOUS_COOKIE and place it in the identifier so we can + * complete the handshake when receiving the acknowledgement. */ + crypto_rand((char *) circ->hs_ident->rendezvous_cookie, HS_REND_COOKIE_LEN); + /* Generate the client keypair. No need to be extra strong, not long term */ + curve25519_keypair_generate(&circ->hs_ident->rendezvous_client_kp, 0); + + cell_len = + hs_cell_build_establish_rendezvous(circ->hs_ident->rendezvous_cookie, + cell); + if (BUG(cell_len < 0)) { + goto err; + } + + if (relay_send_command_from_edge(CONTROL_CELL_ID, TO_CIRCUIT(circ), + RELAY_COMMAND_ESTABLISH_RENDEZVOUS, + (const char *) cell, cell_len, + circ->cpath->prev) < 0) { + /* Circuit has been marked for close */ + log_warn(LD_REND, "Unable to send ESTABLISH_RENDEZVOUS cell on " + "circuit %u", TO_CIRCUIT(circ)->n_circ_id); + memwipe(cell, 0, cell_len); + goto err; + } + + memwipe(cell, 0, cell_len); + return 0; + err: + return -1; +} + +/* We are about to close or free this <b>circ</b>. Clean it up from any + * related HS data structures. This function can be called multiple times + * safely for the same circuit. */ +void +hs_circ_cleanup(circuit_t *circ) +{ + tor_assert(circ); + + /* If it's a service-side intro circ, notify the HS subsystem for the intro + * point circuit closing so it can be dealt with cleanly. */ + if (circ->purpose == CIRCUIT_PURPOSE_S_ESTABLISH_INTRO || + circ->purpose == CIRCUIT_PURPOSE_S_INTRO) { + hs_service_intro_circ_has_closed(TO_ORIGIN_CIRCUIT(circ)); + } + + /* Clear HS circuitmap token for this circ (if any). Very important to be + * done after the HS subsystem has been notified of the close else the + * circuit will not be found. + * + * We do this at the close if possible because from that point on, the + * circuit is good as dead. We can't rely on removing it in the circuit + * free() function because we open a race window between the close and free + * where we can't register a new circuit for the same intro point. */ + if (circ->hs_token) { + hs_circuitmap_remove_circuit(circ); + } +} + |