[tor-commits] [tor/master] prop224: Build INTRODUCE1 cell and send logic

commit d599325b5e1f92395742c3380112b4d2d7cbe9db Author: David Goulet dgoulet@torproject.org Date: Fri Jul 14 10:16:48 2017 -0400

prop224: Build INTRODUCE1 cell and send logic

Add a function in hs_cell.{c|h} for a client to build an INTRODUCE1 cell using an object that contains all the needed keys to do so.

Add an entry point in hs_client.c that allows a tor client to send an INTRODUCE1 cell on a given introduction circuit.

It includes the building of the cell, sending it and the setup of the rendezvous circuit with the circuit identifier.

The entry point function is still unused at this commit.

Signed-off-by: David Goulet dgoulet@torproject.org --- src/or/hs_cell.c | 265 ++++++++++++++++++++++++++++++++++++++++++++++++++++ src/or/hs_cell.h | 30 ++++++ src/or/hs_circuit.c | 147 +++++++++++++++++++++++++++++ src/or/hs_circuit.h | 4 + src/or/hs_client.c | 180 ++++++++++++++++++++++++++++++++++- src/or/hs_client.h | 3 + 6 files changed, 626 insertions(+), 3 deletions(-)

diff --git a/src/or/hs_cell.c b/src/or/hs_cell.c index 7728b7705..889cf7749 100644 --- a/src/or/hs_cell.c +++ b/src/or/hs_cell.c @@ -10,6 +10,7 @@ #include "config.h" #include "rendservice.h" #include "replaycache.h" +#include "util.h"

#include "hs_cell.h" #include "hs_ntor.h" @@ -245,6 +246,229 @@ parse_introduce2_cell(const hs_service_t *service, return -1; }

+/* Set the onion public key onion_pk in cell, the encrypted section of an + * INTRODUCE1 cell. */ +static void +introduce1_set_encrypted_onion_key(trn_cell_introduce_encrypted_t *cell, + const uint8_t *onion_pk) +{ + tor_assert(cell); + tor_assert(onion_pk); + /* There is only one possible key type for a non legacy cell. */ + trn_cell_introduce_encrypted_set_onion_key_type(cell, + HS_CELL_ONION_KEY_TYPE_NTOR); + trn_cell_introduce_encrypted_set_onion_key_len(cell, CURVE25519_PUBKEY_LEN); + trn_cell_introduce_encrypted_setlen_onion_key(cell, CURVE25519_PUBKEY_LEN); + memcpy(trn_cell_introduce_encrypted_getarray_onion_key(cell), onion_pk, + trn_cell_introduce_encrypted_getlen_onion_key(cell)); +} + +/* Set the link specifiers in lspecs in cell, the encrypted section of an + * INTRODUCE1 cell. */ +static void +introduce1_set_encrypted_link_spec(trn_cell_introduce_encrypted_t *cell, + const smartlist_t *lspecs) +{ + tor_assert(cell); + tor_assert(lspecs); + tor_assert(smartlist_len(lspecs) > 0); + tor_assert(smartlist_len(lspecs) <= UINT8_MAX); + + uint8_t lspecs_num = (uint8_t) smartlist_len(lspecs); + trn_cell_introduce_encrypted_set_nspec(cell, lspecs_num); + /* We aren't duplicating the link specifiers object here which means that + * the ownership goes to the trn_cell_introduce_encrypted_t cell and those + * object will be freed when the cell is. */ + SMARTLIST_FOREACH(lspecs, link_specifier_t *, ls, + trn_cell_introduce_encrypted_add_nspecs(cell, ls)); +} + +/* Set padding in the enc_cell only if needed that is the total length of both + * sections are below the mininum required for an INTRODUCE1 cell. */ +static void +introduce1_set_encrypted_padding(const trn_cell_introduce1_t *cell, + trn_cell_introduce_encrypted_t *enc_cell) +{ + tor_assert(cell); + tor_assert(enc_cell); + /* This is the length we expect to have once encoded of the whole cell. */ + ssize_t full_len = trn_cell_introduce1_encoded_len(cell) + + trn_cell_introduce_encrypted_encoded_len(enc_cell); + tor_assert(full_len > 0); + if (full_len < HS_CELL_INTRODUCE1_MIN_SIZE) { + size_t padding = HS_CELL_INTRODUCE1_MIN_SIZE - full_len; + trn_cell_introduce_encrypted_setlen_pad(enc_cell, padding); + memset(trn_cell_introduce_encrypted_getarray_pad(enc_cell), 0, + trn_cell_introduce_encrypted_getlen_pad(enc_cell)); + } +} + +/* Encrypt the ENCRYPTED payload and encode it in the cell using the enc_cell + * and the INTRODUCE1 data. + * + * This can't fail but it is very important that the caller sets every field + * in data so the computation of the INTRODUCE1 keys doesn't fail. */ +static void +introduce1_encrypt_and_encode(trn_cell_introduce1_t *cell, + const trn_cell_introduce_encrypted_t *enc_cell, + const hs_cell_introduce1_data_t *data) +{ + size_t offset = 0; + ssize_t encrypted_len; + ssize_t encoded_cell_len, encoded_enc_cell_len; + uint8_t encoded_cell[RELAY_PAYLOAD_SIZE] = {0}; + uint8_t encoded_enc_cell[RELAY_PAYLOAD_SIZE] = {0}; + uint8_t *encrypted = NULL; + uint8_t mac[DIGEST256_LEN]; + crypto_cipher_t *cipher = NULL; + hs_ntor_intro_cell_keys_t keys; + + tor_assert(cell); + tor_assert(enc_cell); + tor_assert(data); + + /* Encode the cells up to now of what we have to we can perform the MAC + * computation on it. */ + encoded_cell_len = trn_cell_introduce1_encode(encoded_cell, + sizeof(encoded_cell), cell); + /* We have a much more serious issue if this isn't true. */ + tor_assert(encoded_cell_len > 0); + + encoded_enc_cell_len = + trn_cell_introduce_encrypted_encode(encoded_enc_cell, + sizeof(encoded_enc_cell), enc_cell); + /* We have a much more serious issue if this isn't true. */ + tor_assert(encoded_enc_cell_len > 0); + + /* Get the key material for the encryption. */ + if (hs_ntor_client_get_introduce1_keys(data->auth_pk, data->enc_pk, + data->client_kp, + data->subcredential, &keys) < 0) { + tor_assert_unreached(); + } + + /* Prepare cipher with the encryption key just computed. */ + cipher = crypto_cipher_new_with_bits((const char *) keys.enc_key, + sizeof(keys.enc_key) * 8); + tor_assert(cipher); + + /* Compute the length of the ENCRYPTED section which is the CLIENT_PK, + * ENCRYPTED_DATA and MAC length. */ + encrypted_len = sizeof(data->client_kp->pubkey) + encoded_enc_cell_len + + sizeof(mac); + tor_assert(encrypted_len < RELAY_PAYLOAD_SIZE); + encrypted = tor_malloc_zero(encrypted_len); + + /* Put the CLIENT_PK first. */ + memcpy(encrypted, data->client_kp->pubkey.public_key, + sizeof(data->client_kp->pubkey.public_key)); + offset += sizeof(data->client_kp->pubkey.public_key); + /* Then encrypt and set the ENCRYPTED_DATA. This can't fail. */ + crypto_cipher_encrypt(cipher, (char *) encrypted + offset, + (const char *) encoded_enc_cell, encoded_enc_cell_len); + crypto_cipher_free(cipher); + offset += encoded_enc_cell_len; + /* Compute MAC from the above and put it in the buffer. This function will + * make the adjustment to the encryptled_len to ommit the MAC length. */ + compute_introduce_mac(encoded_cell, encoded_cell_len, + encrypted, encrypted_len, + keys.mac_key, sizeof(keys.mac_key), + mac, sizeof(mac)); + memcpy(encrypted + offset, mac, sizeof(mac)); + offset += sizeof(mac); + tor_assert(offset == (size_t) encrypted_len); + + /* Set the ENCRYPTED section in the cell. */ + trn_cell_introduce1_setlen_encrypted(cell, encrypted_len); + memcpy(trn_cell_introduce1_getarray_encrypted(cell), + encrypted, encrypted_len); + + /* Cleanup. */ + memwipe(&keys, 0, sizeof(keys)); + memwipe(mac, 0, sizeof(mac)); + memwipe(encrypted, 0, sizeof(encrypted_len)); + memwipe(encoded_enc_cell, 0, sizeof(encoded_enc_cell)); + tor_free(encrypted); +} + +/* Using the INTRODUCE1 data, setup the ENCRYPTED section in cell. This means + * set it, encrypt it and encode it. */ +static void +introduce1_set_encrypted(trn_cell_introduce1_t *cell, + const hs_cell_introduce1_data_t *data) +{ + trn_cell_introduce_encrypted_t *enc_cell; + trn_cell_extension_t *ext; + + tor_assert(cell); + tor_assert(data); + + enc_cell = trn_cell_introduce_encrypted_new(); + tor_assert(enc_cell); + + /* Set extension data. None are used. */ + ext = trn_cell_extension_new(); + tor_assert(ext); + trn_cell_extension_set_num(ext, 0); + trn_cell_introduce_encrypted_set_extensions(enc_cell, ext); + + /* Set the rendezvous cookie. */ + memcpy(trn_cell_introduce_encrypted_getarray_rend_cookie(enc_cell), + data->rendezvous_cookie, REND_COOKIE_LEN); + + /* Set the onion public key. */ + introduce1_set_encrypted_onion_key(enc_cell, data->onion_pk->public_key); + + /* Set the link specifiers. */ + introduce1_set_encrypted_link_spec(enc_cell, data->link_specifiers); + + /* Set padding. */ + introduce1_set_encrypted_padding(cell, enc_cell); + + /* Encrypt and encode it in the cell. */ + introduce1_encrypt_and_encode(cell, enc_cell, data); + + /* Cleanup. */ + trn_cell_introduce_encrypted_free(enc_cell); +} + +/* Set the authentication key in the INTRODUCE1 cell from the given data. */ +static void +introduce1_set_auth_key(trn_cell_introduce1_t *cell, + const hs_cell_introduce1_data_t *data) +{ + tor_assert(cell); + tor_assert(data); + /* There is only one possible type for a non legacy cell. */ + trn_cell_introduce1_set_auth_key_type(cell, HS_INTRO_AUTH_KEY_TYPE_ED25519); + trn_cell_introduce1_set_auth_key_len(cell, ED25519_PUBKEY_LEN); + trn_cell_introduce1_setlen_auth_key(cell, ED25519_PUBKEY_LEN); + memcpy(trn_cell_introduce1_getarray_auth_key(cell), + data->auth_pk->pubkey, trn_cell_introduce1_getlen_auth_key(cell)); +} + +/* Set the legacy ID field in the INTRODUCE1 cell from the given data. */ +static void +introduce1_set_legacy_id(trn_cell_introduce1_t *cell, + const hs_cell_introduce1_data_t *data) +{ + tor_assert(cell); + tor_assert(data); + + if (data->is_legacy) { + uint8_t digest[DIGEST_LEN]; + if (BUG(crypto_pk_get_digest(data->legacy_key, (char *) digest) < 0)) { + return; + } + memcpy(trn_cell_introduce1_getarray_legacy_key_id(cell), + digest, trn_cell_introduce1_getlen_legacy_key_id(cell)); + } else { + /* We have to zeroed the LEGACY_KEY_ID field. */ + memset(trn_cell_introduce1_getarray_legacy_key_id(cell), 0, + trn_cell_introduce1_getlen_legacy_key_id(cell)); + } +} + /* ========== */ /* Public API */ /* ========== */ @@ -582,3 +806,44 @@ hs_cell_build_rendezvous1(const uint8_t *rendezvous_cookie, return cell_len; }

+/* Build an INTRODUCE1 cell from the given data. The encoded cell is put in + * cell_out which must be of at least size RELAY_PAYLOAD_SIZE. On success, the + * encoded length is returned else a negative value and the content of + * cell_out should be ignored. */ +ssize_t +hs_cell_build_introduce1(const hs_cell_introduce1_data_t *data, + uint8_t *cell_out) +{ + ssize_t cell_len; + trn_cell_introduce1_t *cell; + trn_cell_extension_t *ext; + + tor_assert(data); + tor_assert(cell_out); + + cell = trn_cell_introduce1_new(); + tor_assert(cell); + + /* Set extension data. None are used. */ + ext = trn_cell_extension_new(); + tor_assert(ext); + trn_cell_extension_set_num(ext, 0); + trn_cell_introduce1_set_extensions(cell, ext); + + /* Set the legacy ID field. */ + introduce1_set_legacy_id(cell, data); + + /* Set the authentication key. */ + introduce1_set_auth_key(cell, data); + + /* Set the encrypted section. This will set, encrypt and encode the + * ENCRYPTED section in the cell. After this, we'll be ready to encode. */ + introduce1_set_encrypted(cell, data); + + /* Final encoding. */ + cell_len = trn_cell_introduce1_encode(cell_out, RELAY_PAYLOAD_SIZE, cell); + + trn_cell_introduce1_free(cell); + return cell_len; +} + diff --git a/src/or/hs_cell.h b/src/or/hs_cell.h index f32f7a421..a72009510 100644 --- a/src/or/hs_cell.h +++ b/src/or/hs_cell.h @@ -12,11 +12,39 @@ #include "or.h" #include "hs_service.h"

+/* An INTRODUCE1 cell requires at least this amount of bytes (see section + * 3.2.2 of the specification). Below this value, the cell must be padded. */ +#define HS_CELL_INTRODUCE1_MIN_SIZE 246 + /* Onion key type found in the INTRODUCE1 cell. */ typedef enum { HS_CELL_ONION_KEY_TYPE_NTOR = 1, } hs_cell_onion_key_type_t;

+/* This data structure contains data that we need to build an INTRODUCE1 cell + * used by the INTRODUCE1 build function. */ +typedef struct hs_cell_introduce1_data_t { + /* Is this a legacy introduction point? */ + unsigned int is_legacy : 1; + /* (Legacy only) The encryption key for a legacy intro point. Only set if + * is_legacy is true. */ + const crypto_pk_t *legacy_key; + /* Introduction point authentication public key. */ + const ed25519_public_key_t *auth_pk; + /* Introduction point encryption public key. */ + const curve25519_public_key_t *enc_pk; + /* Subcredentials of the service. */ + const uint8_t *subcredential; + /* Onion public key for the ntor handshake. */ + const curve25519_public_key_t *onion_pk; + /* Rendezvous cookie. */ + const uint8_t *rendezvous_cookie; + /* Public key put before the encrypted data (CLIENT_PK). */ + const curve25519_keypair_t *client_kp; + /* Rendezvous point link specifiers. */ + smartlist_t *link_specifiers; +} hs_cell_introduce1_data_t; + /* This data structure contains data that we need to parse an INTRODUCE2 cell * which is used by the INTRODUCE2 cell parsing function. On a successful * parsing, the onion_pk and rendezvous_cookie will be populated with the @@ -63,6 +91,8 @@ ssize_t hs_cell_build_rendezvous1(const uint8_t *rendezvous_cookie, const uint8_t *rendezvous_handshake_info, size_t rendezvous_handshake_info_len, uint8_t *cell_out); +ssize_t hs_cell_build_introduce1(const hs_cell_introduce1_data_t *data, + uint8_t *cell_out);

/* Parse cell API. */ ssize_t hs_cell_parse_intro_established(const uint8_t *payload, diff --git a/src/or/hs_circuit.c b/src/or/hs_circuit.c index 7704fd0ba..95100e9b3 100644 --- a/src/or/hs_circuit.c +++ b/src/or/hs_circuit.c @@ -530,6 +530,83 @@ retry_service_rendezvous_point(const origin_circuit_t *circ) return; }

+/* Using an extend info object ei, set all possible link specifiers in lspecs. + * IPv4, legacy ID and ed25519 ID are mandatory thus MUST be present in ei. */ +static void +get_lspecs_from_extend_info(const extend_info_t *ei, smartlist_t *lspecs) +{ + link_specifier_t *ls; + + tor_assert(ei); + tor_assert(lspecs); + + /* IPv4 is mandatory. */ + ls = link_specifier_new(); + link_specifier_set_ls_type(ls, LS_IPV4); + link_specifier_set_un_ipv4_addr(ls, tor_addr_to_ipv4h(&ei->addr)); + link_specifier_set_un_ipv4_port(ls, ei->port); + /* Four bytes IPv4 and two bytes port. */ + link_specifier_set_ls_len(ls, sizeof(ei->addr.addr.in_addr) + + sizeof(ei->port)); + smartlist_add(lspecs, ls); + + /* Legacy ID is mandatory. */ + ls = link_specifier_new(); + link_specifier_set_ls_type(ls, LS_LEGACY_ID); + memcpy(link_specifier_getarray_un_legacy_id(ls), ei->identity_digest, + 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 mandatory. */ + ls = link_specifier_new(); + link_specifier_set_ls_type(ls, LS_ED25519_ID); + memcpy(link_specifier_getarray_un_ed25519_id(ls), &ei->ed_identity, + link_specifier_getlen_un_ed25519_id(ls)); + link_specifier_set_ls_len(ls, link_specifier_getlen_un_ed25519_id(ls)); + smartlist_add(lspecs, ls); + + /* XXX: IPv6 is not clearly a thing in extend_info_t? */ +} + +/* Using the given descriptor intro point ip, the extend information of the + * rendezvous point rp_ei and the service's subcredential, populate the + * already allocated intro1_data object with the needed key material and link + * specifiers. + * + * This can't fail but 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 extend_info_t *rp_ei, + const uint8_t *subcredential, + hs_cell_introduce1_data_t *intro1_data) +{ + smartlist_t *rp_lspecs; + + tor_assert(ip); + tor_assert(rp_ei); + 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_extend_info(rp_ei, 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 = &rp_ei->curve25519_onion_key; + intro1_data->link_specifiers = rp_lspecs; +} + /* ========== */ /* Public API */ /* ========== */ @@ -937,3 +1014,73 @@ hs_circuit_setup_e2e_rend_circ_legacy_client(origin_circuit_t *circ, 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); + + /* This takes various objects in order to populate the introduce1 data + * object which is used to build the content of the cell. */ + setup_introduce1_data(ip, rend_circ->build_state->chosen_exit, + subcredential, &intro1_data); + + /* 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: + /* Object in this list have been moved to the cell object when building it + * so they've been freed earlier. We do that in order to avoid duplicating + * them leading to more memory and CPU time being used for nothing. */ + smartlist_free(intro1_data.link_specifiers); + memwipe(&intro1_data, 0, sizeof(intro1_data)); + memwipe(payload, 0, sizeof(payload)); + return ret; +} + diff --git a/src/or/hs_circuit.h b/src/or/hs_circuit.h index 9e359394e..f35ebf17d 100644 --- a/src/or/hs_circuit.h +++ b/src/or/hs_circuit.h @@ -44,6 +44,10 @@ int hs_circ_handle_introduce2(const hs_service_t *service, hs_service_intro_point_t *ip, const uint8_t *subcredential, const uint8_t *payload, size_t payload_len); +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);

/* e2e circuit API. */

diff --git a/src/or/hs_client.c b/src/or/hs_client.c index 514ecf99b..3f951a21a 100644 --- a/src/or/hs_client.c +++ b/src/or/hs_client.c @@ -10,13 +10,48 @@ #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 "circuitlist.h" +#include "circuituse.h" +#include "connection.h" +#include "circpathbias.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 v3 HS circuit successfully connected to the hidden service. Update the * stream state at <b>hs_conn_ident</b> appropriately. */ @@ -140,11 +175,10 @@ fetch_v3_desc(const ed25519_public_key_t *onion_identity_pk) return directory_launch_v3_desc_fetch(onion_identity_pk, hsdir_rs); }

-#if 0 /* Make sure that the given origin circuit circ is a valid correct * introduction circuit. This asserts on validation failure. */ static void -assert_intro_circ(const origin_circuit_t *circ) +assert_intro_circ_ok(const origin_circuit_t *circ) { tor_assert(circ); tor_assert(circ->base_.purpose == CIRCUIT_PURPOSE_C_INTRODUCING); @@ -152,7 +186,131 @@ assert_intro_circ(const origin_circuit_t *circ) tor_assert(hs_ident_intro_circ_is_valid(circ->hs_ident)); assert_circ_anonymity_ok(circ, get_options()); } -#endif + +/* 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; +} + +/* 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; + + assert_intro_circ_ok(intro_circ); + tor_assert(rend_circ); + + 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(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; +} + +/* ========== */ +/* 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. */ @@ -256,3 +414,19 @@ hs_client_refetch_hsdesc(const ed25519_public_key_t *identity_pk) 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); +} + diff --git a/src/or/hs_client.h b/src/or/hs_client.h index 0b446c00b..d8348ddb3 100644 --- a/src/or/hs_client.h +++ b/src/or/hs_client.h @@ -22,5 +22,8 @@ int hs_client_decode_descriptor( int hs_client_any_intro_points_usable(const hs_descriptor_t *desc); int hs_client_refetch_hsdesc(const ed25519_public_key_t *identity_pk);

+int hs_client_send_introduce1(origin_circuit_t *intro_circ, + origin_circuit_t *rend_circ); + #endif /* TOR_HS_CLIENT_H */