diff options
Diffstat (limited to 'src/or/hs_client.c')
| -rw-r--r-- | src/or/hs_client.c | 1181 |
1 files changed, 1175 insertions, 6 deletions
diff --git a/src/or/hs_client.c b/src/or/hs_client.c index 051490aaaf..c0e24ac85c 100644 --- a/src/or/hs_client.c +++ b/src/or/hs_client.c @@ -2,7 +2,7 @@ /* See LICENSE for licensing information */ /** - * \file hs_service.c + * \file hs_client.c * \brief Implement next generation hidden service client functionality **/ @@ -10,14 +10,57 @@ #include "hs_circuit.h" #include "hs_ident.h" #include "connection_edge.h" +#include "container.h" #include "rendclient.h" - +#include "hs_descriptor.h" +#include "hs_cache.h" +#include "hs_cell.h" +#include "hs_ident.h" +#include "config.h" +#include "directory.h" #include "hs_client.h" +#include "router.h" +#include "routerset.h" +#include "circuitlist.h" +#include "circuituse.h" +#include "connection.h" +#include "circpathbias.h" +#include "connection.h" +#include "hs_ntor.h" +#include "circuitbuild.h" + +/* Get all connections that are waiting on a circuit and flag them back to + * waiting for a hidden service descriptor for the given service key + * service_identity_pk. */ +static void +flag_all_conn_wait_desc(const ed25519_public_key_t *service_identity_pk) +{ + tor_assert(service_identity_pk); + + smartlist_t *conns = + connection_list_by_type_state(CONN_TYPE_AP, AP_CONN_STATE_CIRCUIT_WAIT); + + SMARTLIST_FOREACH_BEGIN(conns, connection_t *, conn) { + edge_connection_t *edge_conn; + if (BUG(!CONN_IS_EDGE(conn))) { + continue; + } + edge_conn = TO_EDGE_CONN(conn); + if (edge_conn->hs_ident && + ed25519_pubkey_eq(&edge_conn->hs_ident->identity_pk, + service_identity_pk)) { + connection_ap_mark_as_non_pending_circuit(TO_ENTRY_CONN(conn)); + conn->state = AP_CONN_STATE_RENDDESC_WAIT; + } + } SMARTLIST_FOREACH_END(conn); + + smartlist_free(conns); +} -/** A prop224 v3 HS circuit successfully connected to the hidden - * service. Update the stream state at <b>hs_conn_ident</b> appropriately. */ +/* A v3 HS circuit successfully connected to the hidden service. Update the + * stream state at <b>hs_conn_ident</b> appropriately. */ static void -hs_client_attempt_succeeded(const hs_ident_edge_conn_t *hs_conn_ident) +note_connection_attempt_succeeded(const hs_ident_edge_conn_t *hs_conn_ident) { (void) hs_conn_ident; @@ -25,6 +68,756 @@ hs_client_attempt_succeeded(const hs_ident_edge_conn_t *hs_conn_ident) return; } +/* Given the pubkey of a hidden service in <b>onion_identity_pk</b>, fetch its + * descriptor by launching a dir connection to <b>hsdir</b>. Return 1 on + * success or -1 on error. */ +static int +directory_launch_v3_desc_fetch(const ed25519_public_key_t *onion_identity_pk, + const routerstatus_t *hsdir) +{ + uint64_t current_time_period = hs_get_time_period_num(approx_time()); + ed25519_public_key_t blinded_pubkey; + char base64_blinded_pubkey[ED25519_BASE64_LEN + 1]; + hs_ident_dir_conn_t hs_conn_dir_ident; + int retval; + + tor_assert(hsdir); + tor_assert(onion_identity_pk); + + /* Get blinded pubkey */ + hs_build_blinded_pubkey(onion_identity_pk, NULL, 0, + current_time_period, &blinded_pubkey); + /* ...and base64 it. */ + retval = ed25519_public_to_base64(base64_blinded_pubkey, &blinded_pubkey); + if (BUG(retval < 0)) { + return -1; + } + + /* Copy onion pk to a dir_ident so that we attach it to the dir conn */ + ed25519_pubkey_copy(&hs_conn_dir_ident.identity_pk, onion_identity_pk); + + /* Setup directory request */ + directory_request_t *req = + directory_request_new(DIR_PURPOSE_FETCH_HSDESC); + directory_request_set_routerstatus(req, hsdir); + directory_request_set_indirection(req, DIRIND_ANONYMOUS); + directory_request_set_resource(req, base64_blinded_pubkey); + directory_request_fetch_set_hs_ident(req, &hs_conn_dir_ident); + directory_initiate_request(req); + directory_request_free(req); + + log_info(LD_REND, "Descriptor fetch request for service %s with blinded " + "key %s to directory %s", + safe_str_client(ed25519_fmt(onion_identity_pk)), + safe_str_client(base64_blinded_pubkey), + safe_str_client(routerstatus_describe(hsdir))); + + /* Cleanup memory. */ + memwipe(&blinded_pubkey, 0, sizeof(blinded_pubkey)); + memwipe(base64_blinded_pubkey, 0, sizeof(base64_blinded_pubkey)); + memwipe(&hs_conn_dir_ident, 0, sizeof(hs_conn_dir_ident)); + + return 1; +} + +/** Return the HSDir we should use to fetch the descriptor of the hidden + * service with identity key <b>onion_identity_pk</b>. */ +static routerstatus_t * +pick_hsdir_v3(const ed25519_public_key_t *onion_identity_pk) +{ + int retval; + char base64_blinded_pubkey[ED25519_BASE64_LEN + 1]; + uint64_t current_time_period = hs_get_time_period_num(approx_time()); + smartlist_t *responsible_hsdirs; + ed25519_public_key_t blinded_pubkey; + routerstatus_t *hsdir_rs = NULL; + + tor_assert(onion_identity_pk); + + responsible_hsdirs = smartlist_new(); + + /* Get blinded pubkey of hidden service */ + hs_build_blinded_pubkey(onion_identity_pk, NULL, 0, + current_time_period, &blinded_pubkey); + /* ...and base64 it. */ + retval = ed25519_public_to_base64(base64_blinded_pubkey, &blinded_pubkey); + if (BUG(retval < 0)) { + return NULL; + } + + /* Get responsible hsdirs of service for this time period */ + hs_get_responsible_hsdirs(&blinded_pubkey, current_time_period, 0, 1, + responsible_hsdirs); + + log_debug(LD_REND, "Found %d responsible HSDirs and about to pick one.", + smartlist_len(responsible_hsdirs)); + + /* Pick an HSDir from the responsible ones. The ownership of + * responsible_hsdirs is given to this function so no need to free it. */ + hsdir_rs = hs_pick_hsdir(responsible_hsdirs, base64_blinded_pubkey); + + return hsdir_rs; +} + +/** Fetch a v3 descriptor using the given <b>onion_identity_pk</b>. + * + * On success, 1 is returned. If no hidden service is left to ask, return 0. + * On error, -1 is returned. */ +static int +fetch_v3_desc(const ed25519_public_key_t *onion_identity_pk) +{ + routerstatus_t *hsdir_rs =NULL; + + tor_assert(onion_identity_pk); + + hsdir_rs = pick_hsdir_v3(onion_identity_pk); + if (!hsdir_rs) { + log_info(LD_REND, "Couldn't pick a v3 hsdir."); + return 0; + } + + return directory_launch_v3_desc_fetch(onion_identity_pk, hsdir_rs); +} + +/* Make sure that the given v3 origin circuit circ is a valid correct + * introduction circuit. This will BUG() on any problems and hard assert if + * the anonymity of the circuit is not ok. Return 0 on success else -1 where + * the circuit should be mark for closed immediately. */ +static int +intro_circ_is_ok(const origin_circuit_t *circ) +{ + int ret = 0; + + tor_assert(circ); + + if (BUG(TO_CIRCUIT(circ)->purpose != CIRCUIT_PURPOSE_C_INTRODUCING && + TO_CIRCUIT(circ)->purpose != CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT && + TO_CIRCUIT(circ)->purpose != CIRCUIT_PURPOSE_C_INTRODUCE_ACKED)) { + ret = -1; + } + if (BUG(circ->hs_ident == NULL)) { + ret = -1; + } + if (BUG(!hs_ident_intro_circ_is_valid(circ->hs_ident))) { + ret = -1; + } + + /* This can stop the tor daemon but we want that since if we don't have + * anonymity on this circuit, something went really wrong. */ + assert_circ_anonymity_ok(circ, get_options()); + return ret; +} + +/* Find a descriptor intro point object that matches the given ident in the + * given descriptor desc. Return NULL if not found. */ +static const hs_desc_intro_point_t * +find_desc_intro_point_by_ident(const hs_ident_circuit_t *ident, + const hs_descriptor_t *desc) +{ + const hs_desc_intro_point_t *intro_point = NULL; + + tor_assert(ident); + tor_assert(desc); + + SMARTLIST_FOREACH_BEGIN(desc->encrypted_data.intro_points, + const hs_desc_intro_point_t *, ip) { + if (ed25519_pubkey_eq(&ident->intro_auth_pk, + &ip->auth_key_cert->signed_key)) { + intro_point = ip; + break; + } + } SMARTLIST_FOREACH_END(ip); + + return intro_point; +} + +/* Find a descriptor intro point object from the descriptor object desc that + * matches the given legacy identity digest in legacy_id. Return NULL if not + * found. */ +static hs_desc_intro_point_t * +find_desc_intro_point_by_legacy_id(const char *legacy_id, + const hs_descriptor_t *desc) +{ + hs_desc_intro_point_t *ret_ip = NULL; + + tor_assert(legacy_id); + tor_assert(desc); + + /* We will go over every intro point and try to find which one is linked to + * that circuit. Those lists are small so it's not that expensive. */ + SMARTLIST_FOREACH_BEGIN(desc->encrypted_data.intro_points, + hs_desc_intro_point_t *, ip) { + SMARTLIST_FOREACH_BEGIN(ip->link_specifiers, + const hs_desc_link_specifier_t *, lspec) { + /* Not all tor node have an ed25519 identity key so we still rely on the + * legacy identity digest. */ + if (lspec->type != LS_LEGACY_ID) { + continue; + } + if (fast_memneq(legacy_id, lspec->u.legacy_id, DIGEST_LEN)) { + break; + } + /* Found it. */ + ret_ip = ip; + goto end; + } SMARTLIST_FOREACH_END(lspec); + } SMARTLIST_FOREACH_END(ip); + + end: + return ret_ip; +} + +/* Send an INTRODUCE1 cell along the intro circuit and populate the rend + * circuit identifier with the needed key material for the e2e encryption. + * Return 0 on success, -1 if there is a transient error such that an action + * has been taken to recover and -2 if there is a permanent error indicating + * that both circuits were closed. */ +static int +send_introduce1(origin_circuit_t *intro_circ, + origin_circuit_t *rend_circ) +{ + int status; + char onion_address[HS_SERVICE_ADDR_LEN_BASE32 + 1]; + const ed25519_public_key_t *service_identity_pk = NULL; + const hs_desc_intro_point_t *ip; + + tor_assert(rend_circ); + if (intro_circ_is_ok(intro_circ) < 0) { + goto perm_err; + } + + service_identity_pk = &intro_circ->hs_ident->identity_pk; + /* For logging purposes. There will be a time where the hs_ident will have a + * version number but for now there is none because it's all v3. */ + hs_build_address(service_identity_pk, HS_VERSION_THREE, onion_address); + + log_info(LD_REND, "Sending INTRODUCE1 cell to service %s on circuit %u", + safe_str_client(onion_address), TO_CIRCUIT(intro_circ)->n_circ_id); + + /* 1) Get descriptor from our cache. */ + const hs_descriptor_t *desc = + hs_cache_lookup_as_client(service_identity_pk); + if (desc == NULL || !hs_client_any_intro_points_usable(service_identity_pk, + desc)) { + log_info(LD_REND, "Request to %s %s. Trying to fetch a new descriptor.", + safe_str_client(onion_address), + (desc) ? "didn't have usable intro points" : + "didn't have a descriptor"); + hs_client_refetch_hsdesc(service_identity_pk); + /* We just triggered a refetch, make sure every connections are back + * waiting for that descriptor. */ + flag_all_conn_wait_desc(service_identity_pk); + /* We just asked for a refetch so this is a transient error. */ + goto tran_err; + } + + /* We need to find which intro point in the descriptor we are connected to + * on intro_circ. */ + ip = find_desc_intro_point_by_ident(intro_circ->hs_ident, desc); + if (BUG(ip == NULL)) { + /* If we can find a descriptor from this introduction circuit ident, we + * must have a valid intro point object. Permanent error. */ + goto perm_err; + } + + /* Send the INTRODUCE1 cell. */ + if (hs_circ_send_introduce1(intro_circ, rend_circ, ip, + desc->subcredential) < 0) { + /* Unable to send the cell, the intro circuit has been marked for close so + * this is a permanent error. */ + tor_assert_nonfatal(TO_CIRCUIT(intro_circ)->marked_for_close); + goto perm_err; + } + + /* Cell has been sent successfully. Copy the introduction point + * authentication and encryption key in the rendezvous circuit identifier so + * we can compute the ntor keys when we receive the RENDEZVOUS2 cell. */ + memcpy(&rend_circ->hs_ident->intro_enc_pk, &ip->enc_key, + sizeof(rend_circ->hs_ident->intro_enc_pk)); + ed25519_pubkey_copy(&rend_circ->hs_ident->intro_auth_pk, + &intro_circ->hs_ident->intro_auth_pk); + + /* Now, we wait for an ACK or NAK on this circuit. */ + circuit_change_purpose(TO_CIRCUIT(intro_circ), + CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT); + /* Set timestamp_dirty, because circuit_expire_building expects it to + * specify when a circuit entered the _C_INTRODUCE_ACK_WAIT state. */ + TO_CIRCUIT(intro_circ)->timestamp_dirty = time(NULL); + pathbias_count_use_attempt(intro_circ); + + /* Success. */ + status = 0; + goto end; + + perm_err: + /* Permanent error: it is possible that the intro circuit was closed prior + * because we weren't able to send the cell. Make sure we don't double close + * it which would result in a warning. */ + if (!TO_CIRCUIT(intro_circ)->marked_for_close) { + circuit_mark_for_close(TO_CIRCUIT(intro_circ), END_CIRC_REASON_INTERNAL); + } + circuit_mark_for_close(TO_CIRCUIT(rend_circ), END_CIRC_REASON_INTERNAL); + status = -2; + goto end; + + tran_err: + status = -1; + + end: + memwipe(onion_address, 0, sizeof(onion_address)); + return status; +} + +/* Using the introduction circuit circ, setup the authentication key of the + * intro point this circuit has extended to. */ +static void +setup_intro_circ_auth_key(origin_circuit_t *circ) +{ + const hs_descriptor_t *desc; + const hs_desc_intro_point_t *ip; + + tor_assert(circ); + + desc = hs_cache_lookup_as_client(&circ->hs_ident->identity_pk); + if (BUG(desc == NULL)) { + /* Opening intro circuit without the descriptor is no good... */ + goto end; + } + + /* We will go over every intro point and try to find which one is linked to + * that circuit. Those lists are small so it's not that expensive. */ + ip = find_desc_intro_point_by_legacy_id( + circ->build_state->chosen_exit->identity_digest, desc); + if (ip) { + /* We got it, copy its authentication key to the identifier. */ + ed25519_pubkey_copy(&circ->hs_ident->intro_auth_pk, + &ip->auth_key_cert->signed_key); + goto end; + } + + /* Reaching this point means we didn't find any intro point for this circuit + * which is not suppose to happen. */ + tor_assert_nonfatal_unreached(); + + end: + return; +} + +/* Called when an introduction circuit has opened. */ +static void +client_intro_circ_has_opened(origin_circuit_t *circ) +{ + tor_assert(circ); + tor_assert(TO_CIRCUIT(circ)->purpose == CIRCUIT_PURPOSE_C_INTRODUCING); + log_info(LD_REND, "Introduction circuit %u has opened. Attaching streams.", + (unsigned int) TO_CIRCUIT(circ)->n_circ_id); + + /* This is an introduction circuit so we'll attach the correct + * authentication key to the circuit identifier so it can be identified + * properly later on. */ + setup_intro_circ_auth_key(circ); + + connection_ap_attach_pending(1); +} + +/* Called when a rendezvous circuit has opened. */ +static void +client_rendezvous_circ_has_opened(origin_circuit_t *circ) +{ + tor_assert(circ); + tor_assert(TO_CIRCUIT(circ)->purpose == CIRCUIT_PURPOSE_C_ESTABLISH_REND); + + log_info(LD_REND, "Rendezvous circuit has opened to %s.", + safe_str_client( + extend_info_describe(circ->build_state->chosen_exit))); + + /* Ignore returned value, nothing we can really do. On failure, the circuit + * will be marked for close. */ + hs_circ_send_establish_rendezvous(circ); + + /* Register rend circuit in circuitmap if it's still alive. */ + if (!TO_CIRCUIT(circ)->marked_for_close) { + hs_circuitmap_register_rend_circ_client_side(circ, + circ->hs_ident->rendezvous_cookie); + } +} + +/* This is an helper function that convert a descriptor intro point object ip + * to a newly allocated extend_info_t object fully initialized. Return NULL if + * we can't convert it for which chances are that we are missing or malformed + * link specifiers. */ +static extend_info_t * +desc_intro_point_to_extend_info(const hs_desc_intro_point_t *ip) +{ + extend_info_t *ei; + smartlist_t *lspecs = smartlist_new(); + + tor_assert(ip); + + /* We first encode the descriptor link specifiers into the binary + * representation which is a trunnel object. */ + SMARTLIST_FOREACH_BEGIN(ip->link_specifiers, + const hs_desc_link_specifier_t *, desc_lspec) { + link_specifier_t *lspec = hs_desc_lspec_to_trunnel(desc_lspec); + smartlist_add(lspecs, lspec); + } SMARTLIST_FOREACH_END(desc_lspec); + + /* Explicitely put the direct connection option to 0 because this is client + * side and there is no such thing as a non anonymous client. */ + ei = hs_get_extend_info_from_lspecs(lspecs, &ip->onion_key, 0); + + SMARTLIST_FOREACH(lspecs, link_specifier_t *, ls, link_specifier_free(ls)); + smartlist_free(lspecs); + return ei; +} + +/* Return true iff the intro point ip for the service service_pk is usable. + * This function checks if the intro point is in the client intro state cache + * and checks at the failures. It is considered usable if: + * - No error happened (INTRO_POINT_FAILURE_GENERIC) + * - It is not flagged as timed out (INTRO_POINT_FAILURE_TIMEOUT) + * - The unreachable count is lower than + * MAX_INTRO_POINT_REACHABILITY_FAILURES (INTRO_POINT_FAILURE_UNREACHABLE) + */ +static int +intro_point_is_usable(const ed25519_public_key_t *service_pk, + const hs_desc_intro_point_t *ip) +{ + const hs_cache_intro_state_t *state; + + tor_assert(service_pk); + tor_assert(ip); + + state = hs_cache_client_intro_state_find(service_pk, + &ip->auth_key_cert->signed_key); + if (state == NULL) { + /* This means we've never encountered any problem thus usable. */ + goto usable; + } + if (state->error) { + log_info(LD_REND, "Intro point with auth key %s had an error. Not usable", + safe_str_client(ed25519_fmt(&ip->auth_key_cert->signed_key))); + goto not_usable; + } + if (state->timed_out) { + log_info(LD_REND, "Intro point with auth key %s timed out. Not usable", + safe_str_client(ed25519_fmt(&ip->auth_key_cert->signed_key))); + goto not_usable; + } + if (state->unreachable_count >= MAX_INTRO_POINT_REACHABILITY_FAILURES) { + log_info(LD_REND, "Intro point with auth key %s unreachable. Not usable", + safe_str_client(ed25519_fmt(&ip->auth_key_cert->signed_key))); + goto not_usable; + } + + usable: + return 1; + not_usable: + return 0; +} + +/* Using a descriptor desc, return a newly allocated extend_info_t object of a + * randomly picked introduction point from its list. Return NULL if none are + * usable. */ +static extend_info_t * +client_get_random_intro(const ed25519_public_key_t *service_pk) +{ + extend_info_t *ei = NULL, *ei_excluded = NULL; + smartlist_t *usable_ips = NULL; + const hs_descriptor_t *desc; + const hs_desc_encrypted_data_t *enc_data; + const or_options_t *options = get_options(); + + tor_assert(service_pk); + + desc = hs_cache_lookup_as_client(service_pk); + if (desc == NULL || !hs_client_any_intro_points_usable(service_pk, + desc)) { + log_info(LD_REND, "Unable to randomly select an introduction point " + "because descriptor %s.", + (desc) ? "doesn't have usable intro point" : "is missing"); + goto end; + } + + enc_data = &desc->encrypted_data; + usable_ips = smartlist_new(); + smartlist_add_all(usable_ips, enc_data->intro_points); + while (smartlist_len(usable_ips) != 0) { + int idx; + const hs_desc_intro_point_t *ip; + + /* Pick a random intro point and immediately remove it from the usable + * list so we don't pick it again if we have to iterate more. */ + idx = crypto_rand_int(smartlist_len(usable_ips)); + ip = smartlist_get(usable_ips, idx); + smartlist_del(usable_ips, idx); + + /* We need to make sure we have a usable intro points which is in a good + * state in our cache. */ + if (!intro_point_is_usable(service_pk, ip)) { + continue; + } + + /* Generate an extend info object from the intro point object. */ + ei = desc_intro_point_to_extend_info(ip); + if (ei == NULL) { + /* We can get here for instance if the intro point is a private address + * and we aren't allowed to extend to those. */ + continue; + } + + /* Test the pick against ExcludeNodes. */ + if (routerset_contains_extendinfo(options->ExcludeNodes, ei)) { + /* If this pick is in the ExcludeNodes list, we keep its reference so if + * we ever end up not being able to pick anything else and StrictNodes is + * unset, we'll use it. */ + ei_excluded = ei; + continue; + } + + /* Good pick! Let's go with this. */ + goto end; + } + + /* Reaching this point means a couple of things. Either we can't use any of + * the intro point listed because the IP address can't be extended to or it + * is listed in the ExcludeNodes list. In the later case, if StrictNodes is + * set, we are forced to not use anything. */ + ei = ei_excluded; + if (options->StrictNodes) { + log_warn(LD_REND, "Every introduction points are in the ExcludeNodes set " + "and StrictNodes is set. We can't connect."); + ei = NULL; + } + + end: + smartlist_free(usable_ips); + return ei; +} + +/* For this introduction circuit, we'll look at if we have any usable + * introduction point left for this service. If so, we'll use the circuit to + * re-extend to a new intro point. Else, we'll close the circuit and its + * corresponding rendezvous circuit. Return 0 if we are re-extending else -1 + * if we are closing the circuits. + * + * This is called when getting an INTRODUCE_ACK cell with a NACK. */ +static int +close_or_reextend_intro_circ(origin_circuit_t *intro_circ) +{ + int ret = -1; + const hs_descriptor_t *desc; + origin_circuit_t *rend_circ; + + tor_assert(intro_circ); + + desc = hs_cache_lookup_as_client(&intro_circ->hs_ident->identity_pk); + if (BUG(desc == NULL)) { + /* We can't continue without a descriptor. */ + goto close; + } + /* We still have the descriptor, great! Let's try to see if we can + * re-extend by looking up if there are any usable intro points. */ + if (!hs_client_any_intro_points_usable(&intro_circ->hs_ident->identity_pk, + desc)) { + goto close; + } + /* Try to re-extend now. */ + if (hs_client_reextend_intro_circuit(intro_circ) < 0) { + goto close; + } + /* Success on re-extending. Don't return an error. */ + ret = 0; + goto end; + + close: + /* Change the intro circuit purpose before so we don't report an intro point + * failure again triggering an extra descriptor fetch. The circuit can + * already be closed on failure to re-extend. */ + if (!TO_CIRCUIT(intro_circ)->marked_for_close) { + circuit_change_purpose(TO_CIRCUIT(intro_circ), + CIRCUIT_PURPOSE_C_INTRODUCE_ACKED); + circuit_mark_for_close(TO_CIRCUIT(intro_circ), END_CIRC_REASON_FINISHED); + } + /* Close the related rendezvous circuit. */ + rend_circ = hs_circuitmap_get_rend_circ_client_side( + intro_circ->hs_ident->rendezvous_cookie); + /* The rendezvous circuit might have collapsed while the INTRODUCE_ACK was + * inflight so we can't expect one every time. */ + if (rend_circ) { + circuit_mark_for_close(TO_CIRCUIT(rend_circ), END_CIRC_REASON_FINISHED); + } + + end: + return ret; +} + +/* Called when we get an INTRODUCE_ACK success status code. Do the appropriate + * actions for the rendezvous point and finally close intro_circ. */ +static void +handle_introduce_ack_success(origin_circuit_t *intro_circ) +{ + origin_circuit_t *rend_circ = NULL; + + tor_assert(intro_circ); + + log_info(LD_REND, "Received INTRODUCE_ACK ack! Informing rendezvous"); + + /* Get the rendezvous circuit for this rendezvous cookie. */ + uint8_t *rendezvous_cookie = intro_circ->hs_ident->rendezvous_cookie; + rend_circ = hs_circuitmap_get_rend_circ_client_side(rendezvous_cookie); + if (rend_circ == NULL) { + log_warn(LD_REND, "Can't find any rendezvous circuit. Stopping"); + goto end; + } + + assert_circ_anonymity_ok(rend_circ, get_options()); + circuit_change_purpose(TO_CIRCUIT(rend_circ), + CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED); + /* Set timestamp_dirty, because circuit_expire_building expects it to + * specify when a circuit entered the + * CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED state. */ + TO_CIRCUIT(rend_circ)->timestamp_dirty = time(NULL); + + end: + /* We don't need the intro circuit anymore. It did what it had to do! */ + circuit_change_purpose(TO_CIRCUIT(intro_circ), + CIRCUIT_PURPOSE_C_INTRODUCE_ACKED); + circuit_mark_for_close(TO_CIRCUIT(intro_circ), END_CIRC_REASON_FINISHED); + + /* XXX: Close pending intro circuits we might have in parallel. */ + return; +} + +/* Called when we get an INTRODUCE_ACK failure status code. Depending on our + * failure cache status, either close the circuit or re-extend to a new + * introduction point. */ +static void +handle_introduce_ack_bad(origin_circuit_t *circ, int status) +{ + tor_assert(circ); + + log_info(LD_REND, "Received INTRODUCE_ACK nack by %s. Reason: %u", + safe_str_client(extend_info_describe(circ->build_state->chosen_exit)), + status); + + /* It's a NAK. The introduction point didn't relay our request. */ + circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_C_INTRODUCING); + + /* Note down this failure in the intro point failure cache. Depending on how + * many times we've tried this intro point, close it or reextend. */ + hs_cache_client_intro_state_note(&circ->hs_ident->identity_pk, + &circ->hs_ident->intro_auth_pk, + INTRO_POINT_FAILURE_GENERIC); +} + +/* Called when we get an INTRODUCE_ACK on the intro circuit circ. The encoded + * cell is in payload of length payload_len. Return 0 on success else a + * negative value. The circuit is either close or reuse to re-extend to a new + * introduction point. */ +static int +handle_introduce_ack(origin_circuit_t *circ, const uint8_t *payload, + size_t payload_len) +{ + int status, ret = -1; + + tor_assert(circ); + tor_assert(circ->build_state); + tor_assert(circ->build_state->chosen_exit); + assert_circ_anonymity_ok(circ, get_options()); + tor_assert(payload); + + status = hs_cell_parse_introduce_ack(payload, payload_len); + switch (status) { + case HS_CELL_INTRO_ACK_SUCCESS: + ret = 0; + handle_introduce_ack_success(circ); + goto end; + case HS_CELL_INTRO_ACK_FAILURE: + case HS_CELL_INTRO_ACK_BADFMT: + case HS_CELL_INTRO_ACK_NORELAY: + handle_introduce_ack_bad(circ, status); + /* We are going to see if we have to close the circuits (IP and RP) or we + * can re-extend to a new intro point. */ + ret = close_or_reextend_intro_circ(circ); + break; + default: + log_info(LD_PROTOCOL, "Unknown INTRODUCE_ACK status code %u from %s", + status, + safe_str_client(extend_info_describe(circ->build_state->chosen_exit))); + break; + } + + end: + return ret; +} + +/* Called when we get a RENDEZVOUS2 cell on the rendezvous circuit circ. The + * encoded cell is in payload of length payload_len. Return 0 on success or a + * negative value on error. On error, the circuit is marked for close. */ +static int +handle_rendezvous2(origin_circuit_t *circ, const uint8_t *payload, + size_t payload_len) +{ + int ret = -1; + curve25519_public_key_t server_pk; + uint8_t auth_mac[DIGEST256_LEN] = {0}; + uint8_t handshake_info[CURVE25519_PUBKEY_LEN + sizeof(auth_mac)] = {0}; + hs_ntor_rend_cell_keys_t keys; + const hs_ident_circuit_t *ident; + + tor_assert(circ); + tor_assert(payload); + + /* Make things easier. */ + ident = circ->hs_ident; + tor_assert(ident); + + if (hs_cell_parse_rendezvous2(payload, payload_len, handshake_info, + sizeof(handshake_info)) < 0) { + goto err; + } + /* Get from the handshake info the SERVER_PK and AUTH_MAC. */ + memcpy(&server_pk, handshake_info, CURVE25519_PUBKEY_LEN); + memcpy(auth_mac, handshake_info + CURVE25519_PUBKEY_LEN, sizeof(auth_mac)); + + /* Generate the handshake info. */ + if (hs_ntor_client_get_rendezvous1_keys(&ident->intro_auth_pk, + &ident->rendezvous_client_kp, + &ident->intro_enc_pk, &server_pk, + &keys) < 0) { + log_info(LD_REND, "Unable to compute the rendezvous keys."); + goto err; + } + + /* Critical check, make sure that the MAC matches what we got with what we + * computed just above. */ + if (!hs_ntor_client_rendezvous2_mac_is_good(&keys, auth_mac)) { + log_info(LD_REND, "Invalid MAC in RENDEZVOUS2. Rejecting cell."); + goto err; + } + + /* Setup the e2e encryption on the circuit and finalize its state. */ + if (hs_circuit_setup_e2e_rend_circ(circ, keys.ntor_key_seed, + sizeof(keys.ntor_key_seed), 0) < 0) { + log_info(LD_REND, "Unable to setup the e2e encryption."); + goto err; + } + /* Success. Hidden service connection finalized! */ + ret = 0; + goto end; + + err: + circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL); + end: + memwipe(&keys, 0, sizeof(keys)); + return ret; +} + +/* ========== */ +/* Public API */ +/* ========== */ + /** A circuit just finished connecting to a hidden service that the stream * <b>conn</b> has been waiting for. Let the HS subsystem know about this. */ void @@ -38,7 +831,7 @@ hs_client_note_connection_attempt_succeeded(const edge_connection_t *conn) } if (conn->hs_ident) { /* It's v3: pass it to the prop224 handler */ - hs_client_attempt_succeeded(conn->hs_ident); + note_connection_attempt_succeeded(conn->hs_ident); return; } else if (conn->rend_data) { /* It's v2: pass it to the legacy handler */ rend_client_note_connection_attempt_ended(conn->rend_data); @@ -46,3 +839,379 @@ hs_client_note_connection_attempt_succeeded(const edge_connection_t *conn) } } +/* With the given encoded descriptor in desc_str and the service key in + * service_identity_pk, decode the descriptor and set the desc pointer with a + * newly allocated descriptor object. + * + * Return 0 on success else a negative value and desc is set to NULL. */ +int +hs_client_decode_descriptor(const char *desc_str, + const ed25519_public_key_t *service_identity_pk, + hs_descriptor_t **desc) +{ + int ret; + uint8_t subcredential[DIGEST256_LEN]; + ed25519_public_key_t blinded_pubkey; + + tor_assert(desc_str); + tor_assert(service_identity_pk); + tor_assert(desc); + + /* Create subcredential for this HS so that we can decrypt */ + { + uint64_t current_time_period = hs_get_time_period_num(approx_time()); + hs_build_blinded_pubkey(service_identity_pk, NULL, 0, current_time_period, + &blinded_pubkey); + hs_get_subcredential(service_identity_pk, &blinded_pubkey, subcredential); + } + + /* Parse descriptor */ + ret = hs_desc_decode_descriptor(desc_str, subcredential, desc); + memwipe(subcredential, 0, sizeof(subcredential)); + if (ret < 0) { + log_warn(LD_GENERAL, "Could not parse received descriptor as client"); + goto err; + } + + /* Make sure the descriptor signing key cross certifies with the computed + * blinded key. Without this validation, anyone knowing the subcredential + * and onion address can forge a descriptor. */ + if (tor_cert_checksig((*desc)->plaintext_data.signing_key_cert, + &blinded_pubkey, approx_time()) < 0) { + log_warn(LD_GENERAL, "Descriptor signing key certificate signature " + "doesn't validate with computed blinded key."); + goto err; + } + + return 0; + err: + return -1; +} + +/* Return true iff there are at least one usable intro point in the service + * descriptor desc. */ +int +hs_client_any_intro_points_usable(const ed25519_public_key_t *service_pk, + const hs_descriptor_t *desc) +{ + tor_assert(service_pk); + tor_assert(desc); + + SMARTLIST_FOREACH_BEGIN(desc->encrypted_data.intro_points, + const hs_desc_intro_point_t *, ip) { + if (intro_point_is_usable(service_pk, ip)) { + goto usable; + } + } SMARTLIST_FOREACH_END(ip); + + return 0; + usable: + return 1; +} + +/** Launch a connection to a hidden service directory to fetch a hidden + * service descriptor using <b>identity_pk</b> to get the necessary keys. + * + * On success, 1 is returned. If no hidden service is left to ask, return 0. + * On error, -1 is returned. (retval is only used by unittests right now) */ +int +hs_client_refetch_hsdesc(const ed25519_public_key_t *identity_pk) +{ + tor_assert(identity_pk); + + /* Are we configured to fetch descriptors? */ + if (!get_options()->FetchHidServDescriptors) { + log_warn(LD_REND, "We received an onion address for a hidden service " + "descriptor but we are configured to not fetch."); + return 0; + } + + /* Check if fetching a desc for this HS is useful to us right now */ + { + const hs_descriptor_t *cached_desc = NULL; + cached_desc = hs_cache_lookup_as_client(identity_pk); + if (cached_desc && hs_client_any_intro_points_usable(identity_pk, + cached_desc)) { + log_warn(LD_GENERAL, "We would fetch a v3 hidden service descriptor " + "but we already have a useable descriprot."); + return 0; + } + } + + return fetch_v3_desc(identity_pk); +} + +/* This is called when we are trying to attach an AP connection to these + * hidden service circuits from connection_ap_handshake_attach_circuit(). + * Return 0 on success, -1 for a transient error that is actions were + * triggered to recover or -2 for a permenent error where both circuits will + * marked for close. + * + * The following supports every hidden service version. */ +int +hs_client_send_introduce1(origin_circuit_t *intro_circ, + origin_circuit_t *rend_circ) +{ + return (intro_circ->hs_ident) ? send_introduce1(intro_circ, rend_circ) : + rend_client_send_introduction(intro_circ, + rend_circ); +} + +/* Called when the client circuit circ has been established. It can be either + * an introduction or rendezvous circuit. This function handles all hidden + * service versions. */ +void +hs_client_circuit_has_opened(origin_circuit_t *circ) +{ + tor_assert(circ); + + /* Handle both version. v2 uses rend_data and v3 uses the hs circuit + * identifier hs_ident. Can't be both. */ + switch (TO_CIRCUIT(circ)->purpose) { + case CIRCUIT_PURPOSE_C_INTRODUCING: + if (circ->hs_ident) { + client_intro_circ_has_opened(circ); + } else { + rend_client_introcirc_has_opened(circ); + } + break; + case CIRCUIT_PURPOSE_C_ESTABLISH_REND: + if (circ->hs_ident) { + client_rendezvous_circ_has_opened(circ); + } else { + rend_client_rendcirc_has_opened(circ); + } + break; + default: + tor_assert_nonfatal_unreached(); + } +} + +/* Called when we receive a RENDEZVOUS_ESTABLISHED cell. Change the state of + * the circuit to CIRCUIT_PURPOSE_C_REND_READY. Return 0 on success else a + * negative value and the circuit marked for close. */ +int +hs_client_receive_rendezvous_acked(origin_circuit_t *circ, + const uint8_t *payload, size_t payload_len) +{ + tor_assert(circ); + tor_assert(payload); + + (void) payload_len; + + if (TO_CIRCUIT(circ)->purpose != CIRCUIT_PURPOSE_C_ESTABLISH_REND) { + log_warn(LD_PROTOCOL, "Got a RENDEZVOUS_ESTABLISHED but we were not " + "expecting one. Closing circuit."); + goto err; + } + + log_info(LD_REND, "Received an RENDEZVOUS_ESTABLISHED. This circuit is " + "now ready for rendezvous."); + circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_C_REND_READY); + + /* Set timestamp_dirty, because circuit_expire_building expects it to + * specify when a circuit entered the _C_REND_READY state. */ + TO_CIRCUIT(circ)->timestamp_dirty = time(NULL); + + /* From a path bias point of view, this circuit is now successfully used. + * Waiting any longer opens us up to attacks from malicious hidden services. + * They could induce the client to attempt to connect to their hidden + * service and never reply to the client's rend requests */ + pathbias_mark_use_success(circ); + + /* If we already have the introduction circuit built, make sure we send + * the INTRODUCE cell _now_ */ + connection_ap_attach_pending(1); + + return 0; + err: + circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL); + return -1; +} + +/* This is called when a descriptor has arrived following a fetch request and + * has been stored in the client cache. Every entry connection that matches + * the service identity key in the ident will get attached to the hidden + * service circuit. */ +void +hs_client_desc_has_arrived(const hs_ident_dir_conn_t *ident) +{ + time_t now = time(NULL); + smartlist_t *conns = NULL; + + tor_assert(ident); + + conns = connection_list_by_type_state(CONN_TYPE_AP, + AP_CONN_STATE_RENDDESC_WAIT); + SMARTLIST_FOREACH_BEGIN(conns, connection_t *, base_conn) { + const hs_descriptor_t *desc; + entry_connection_t *entry_conn = TO_ENTRY_CONN(base_conn); + const edge_connection_t *edge_conn = ENTRY_TO_EDGE_CONN(entry_conn); + + /* Only consider the entry connections that matches the service for which + * we just fetched its descriptor. */ + if (!edge_conn->hs_ident || + !ed25519_pubkey_eq(&ident->identity_pk, + &edge_conn->hs_ident->identity_pk)) { + continue; + } + assert_connection_ok(base_conn, now); + + /* We were just called because we stored the descriptor for this service + * so not finding a descriptor means we have a bigger problem. */ + desc = hs_cache_lookup_as_client(&ident->identity_pk); + if (BUG(desc == NULL)) { + goto end; + } + + if (!hs_client_any_intro_points_usable(&ident->identity_pk, desc)) { + log_info(LD_REND, "Hidden service descriptor is unusable. " + "Closing streams."); + connection_mark_unattached_ap(entry_conn, + END_STREAM_REASON_RESOLVEFAILED); + /* XXX: Note the connection attempt. */ + goto end; + } + + log_info(LD_REND, "Descriptor has arrived. Launching circuits."); + + /* Restart their timeout values, so they get a fair shake at connecting to + * the hidden service. XXX: Improve comment on why this is needed. */ + base_conn->timestamp_created = now; + base_conn->timestamp_lastread = now; + base_conn->timestamp_lastwritten = now; + /* Change connection's state into waiting for a circuit. */ + base_conn->state = AP_CONN_STATE_CIRCUIT_WAIT; + + connection_ap_mark_as_pending_circuit(entry_conn); + } SMARTLIST_FOREACH_END(base_conn); + + end: + /* We don't have ownership of the objects in this list. */ + smartlist_free(conns); +} + +/* Return a newly allocated extend_info_t for a randomly chosen introduction + * point for the given edge connection identifier ident. Return NULL if we + * can't pick any usable introduction points. */ +extend_info_t * +hs_client_get_random_intro_from_edge(const edge_connection_t *edge_conn) +{ + tor_assert(edge_conn); + + return (edge_conn->hs_ident) ? + client_get_random_intro(&edge_conn->hs_ident->identity_pk) : + rend_client_get_random_intro(edge_conn->rend_data); +} +/* Called when get an INTRODUCE_ACK cell on the introduction circuit circ. + * Return 0 on success else a negative value is returned. The circuit will be + * closed or reuse to extend again to another intro point. */ +int +hs_client_receive_introduce_ack(origin_circuit_t *circ, + const uint8_t *payload, size_t payload_len) +{ + int ret = -1; + + tor_assert(circ); + tor_assert(payload); + + if (TO_CIRCUIT(circ)->purpose != CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT) { + log_warn(LD_PROTOCOL, "Unexpected INTRODUCE_ACK on circuit %u.", + (unsigned int) TO_CIRCUIT(circ)->n_circ_id); + circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL); + goto end; + } + + ret = (circ->hs_ident) ? handle_introduce_ack(circ, payload, payload_len) : + rend_client_introduction_acked(circ, payload, + payload_len); + /* For path bias: This circuit was used successfully. NACK or ACK counts. */ + pathbias_mark_use_success(circ); + + end: + return ret; +} + +/* Called when get a RENDEZVOUS2 cell on the rendezvous circuit circ. Return + * 0 on success else a negative value is returned. The circuit will be closed + * on error. */ +int +hs_client_receive_rendezvous2(origin_circuit_t *circ, + const uint8_t *payload, size_t payload_len) +{ + int ret = -1; + + tor_assert(circ); + tor_assert(payload); + + /* Circuit can possibly be in both state because we could receive a + * RENDEZVOUS2 cell before the INTRODUCE_ACK has been received. */ + if (TO_CIRCUIT(circ)->purpose != CIRCUIT_PURPOSE_C_REND_READY && + TO_CIRCUIT(circ)->purpose != CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED) { + log_warn(LD_PROTOCOL, "Unexpected RENDEZVOUS2 cell on circuit %u. " + "Closing circuit.", + (unsigned int) TO_CIRCUIT(circ)->n_circ_id); + circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL); + goto end; + } + + log_info(LD_REND, "Got RENDEZVOUS2 cell from hidden service on circuit %u.", + TO_CIRCUIT(circ)->n_circ_id); + + ret = (circ->hs_ident) ? handle_rendezvous2(circ, payload, payload_len) : + rend_client_receive_rendezvous(circ, payload, + payload_len); + end: + return ret; +} + +/* Extend the introduction circuit circ to another valid introduction point + * for the hidden service it is trying to connect to, or mark it and launch a + * new circuit if we can't extend it. Return 0 on success or possible + * success. Return -1 and mark the introduction circuit for close on permanent + * failure. + * + * On failure, the caller is responsible for marking the associated rendezvous + * circuit for close. */ +int +hs_client_reextend_intro_circuit(origin_circuit_t *circ) +{ + int ret = -1; + extend_info_t *ei; + + tor_assert(circ); + + ei = (circ->hs_ident) ? + client_get_random_intro(&circ->hs_ident->identity_pk) : + rend_client_get_random_intro(circ->rend_data); + if (ei == NULL) { + log_warn(LD_REND, "No usable introduction points left. Closing."); + circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL); + goto end; + } + + if (circ->remaining_relay_early_cells) { + log_info(LD_REND, "Re-extending circ %u, this time to %s.", + (unsigned int) TO_CIRCUIT(circ)->n_circ_id, + safe_str_client(extend_info_describe(ei))); + ret = circuit_extend_to_new_exit(circ, ei); + if (ret == 0) { + /* We were able to extend so update the timestamp so we avoid expiring + * this circuit too early. The intro circuit is short live so the + * linkability issue is minimized, we just need the circuit to hold a + * bit longer so we can introduce. */ + TO_CIRCUIT(circ)->timestamp_dirty = time(NULL); + } + } else { + log_info(LD_REND, "Closing intro circ %u (out of RELAY_EARLY cells).", + (unsigned int) TO_CIRCUIT(circ)->n_circ_id); + circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_FINISHED); + /* connection_ap_handshake_attach_circuit will launch a new intro circ. */ + ret = 0; + } + + end: + extend_info_free(ei); + return ret; +} + |