diff options
Diffstat (limited to 'src/or/hs_intropoint.c')
| -rw-r--r-- | src/or/hs_intropoint.c | 614 |
1 files changed, 0 insertions, 614 deletions
diff --git a/src/or/hs_intropoint.c b/src/or/hs_intropoint.c deleted file mode 100644 index 2594058679..0000000000 --- a/src/or/hs_intropoint.c +++ /dev/null @@ -1,614 +0,0 @@ -/* Copyright (c) 2016-2018, The Tor Project, Inc. */ -/* See LICENSE for licensing information */ - -/** - * \file hs_intropoint.c - * \brief Implement next generation introductions point functionality - **/ - -#define HS_INTROPOINT_PRIVATE - -#include "or/or.h" -#include "or/config.h" -#include "or/circuitlist.h" -#include "or/circuituse.h" -#include "or/relay.h" -#include "or/rendmid.h" -#include "or/rephist.h" -#include "lib/crypt_ops/crypto_format.h" - -/* Trunnel */ -#include "trunnel/ed25519_cert.h" -#include "trunnel/hs/cell_common.h" -#include "trunnel/hs/cell_establish_intro.h" -#include "trunnel/hs/cell_introduce1.h" - -#include "or/hs_circuitmap.h" -#include "or/hs_descriptor.h" -#include "or/hs_intropoint.h" -#include "or/hs_common.h" - -#include "or/or_circuit_st.h" - -/** Extract the authentication key from an ESTABLISH_INTRO or INTRODUCE1 using - * the given <b>cell_type</b> from <b>cell</b> and place it in - * <b>auth_key_out</b>. */ -STATIC void -get_auth_key_from_cell(ed25519_public_key_t *auth_key_out, - unsigned int cell_type, const void *cell) -{ - size_t auth_key_len; - const uint8_t *key_array; - - tor_assert(auth_key_out); - tor_assert(cell); - - switch (cell_type) { - case RELAY_COMMAND_ESTABLISH_INTRO: - { - const trn_cell_establish_intro_t *c_cell = cell; - key_array = trn_cell_establish_intro_getconstarray_auth_key(c_cell); - auth_key_len = trn_cell_establish_intro_getlen_auth_key(c_cell); - break; - } - case RELAY_COMMAND_INTRODUCE1: - { - const trn_cell_introduce1_t *c_cell = cell; - key_array = trn_cell_introduce1_getconstarray_auth_key(cell); - auth_key_len = trn_cell_introduce1_getlen_auth_key(c_cell); - break; - } - default: - /* Getting here is really bad as it means we got a unknown cell type from - * this file where every call has an hardcoded value. */ - tor_assert(0); /* LCOV_EXCL_LINE */ - } - tor_assert(key_array); - tor_assert(auth_key_len == sizeof(auth_key_out->pubkey)); - memcpy(auth_key_out->pubkey, key_array, auth_key_len); -} - -/** We received an ESTABLISH_INTRO <b>cell</b>. Verify its signature and MAC, - * given <b>circuit_key_material</b>. Return 0 on success else -1 on error. */ -STATIC int -verify_establish_intro_cell(const trn_cell_establish_intro_t *cell, - const uint8_t *circuit_key_material, - size_t circuit_key_material_len) -{ - /* We only reach this function if the first byte of the cell is 0x02 which - * means that auth_key_type is of ed25519 type, hence this check should - * always pass. See hs_intro_received_establish_intro(). */ - if (BUG(cell->auth_key_type != HS_INTRO_AUTH_KEY_TYPE_ED25519)) { - return -1; - } - - /* Make sure the auth key length is of the right size for this type. For - * EXTRA safety, we check both the size of the array and the length which - * must be the same. Safety first!*/ - if (trn_cell_establish_intro_getlen_auth_key(cell) != ED25519_PUBKEY_LEN || - trn_cell_establish_intro_get_auth_key_len(cell) != ED25519_PUBKEY_LEN) { - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, - "ESTABLISH_INTRO auth key length is invalid"); - return -1; - } - - const uint8_t *msg = cell->start_cell; - - /* Verify the sig */ - { - ed25519_signature_t sig_struct; - const uint8_t *sig_array = - trn_cell_establish_intro_getconstarray_sig(cell); - - /* Make sure the signature length is of the right size. For EXTRA safety, - * we check both the size of the array and the length which must be the - * same. Safety first!*/ - if (trn_cell_establish_intro_getlen_sig(cell) != sizeof(sig_struct.sig) || - trn_cell_establish_intro_get_sig_len(cell) != sizeof(sig_struct.sig)) { - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, - "ESTABLISH_INTRO sig len is invalid"); - return -1; - } - /* We are now sure that sig_len is of the right size. */ - memcpy(sig_struct.sig, sig_array, cell->sig_len); - - ed25519_public_key_t auth_key; - get_auth_key_from_cell(&auth_key, RELAY_COMMAND_ESTABLISH_INTRO, cell); - - const size_t sig_msg_len = cell->end_sig_fields - msg; - int sig_mismatch = ed25519_checksig_prefixed(&sig_struct, - msg, sig_msg_len, - ESTABLISH_INTRO_SIG_PREFIX, - &auth_key); - if (sig_mismatch) { - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, - "ESTABLISH_INTRO signature not as expected"); - return -1; - } - } - - /* Verify the MAC */ - { - const size_t auth_msg_len = cell->end_mac_fields - msg; - uint8_t mac[DIGEST256_LEN]; - crypto_mac_sha3_256(mac, sizeof(mac), - circuit_key_material, circuit_key_material_len, - msg, auth_msg_len); - if (tor_memneq(mac, cell->handshake_mac, sizeof(mac))) { - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, - "ESTABLISH_INTRO handshake_auth not as expected"); - return -1; - } - } - - return 0; -} - -/* Send an INTRO_ESTABLISHED cell to <b>circ</b>. */ -MOCK_IMPL(int, -hs_intro_send_intro_established_cell,(or_circuit_t *circ)) -{ - int ret; - uint8_t *encoded_cell = NULL; - ssize_t encoded_len, result_len; - trn_cell_intro_established_t *cell; - trn_cell_extension_t *ext; - - tor_assert(circ); - - /* Build the cell payload. */ - cell = trn_cell_intro_established_new(); - ext = trn_cell_extension_new(); - trn_cell_extension_set_num(ext, 0); - trn_cell_intro_established_set_extensions(cell, ext); - /* Encode the cell to binary format. */ - encoded_len = trn_cell_intro_established_encoded_len(cell); - tor_assert(encoded_len > 0); - encoded_cell = tor_malloc_zero(encoded_len); - result_len = trn_cell_intro_established_encode(encoded_cell, encoded_len, - cell); - tor_assert(encoded_len == result_len); - - ret = relay_send_command_from_edge(0, TO_CIRCUIT(circ), - RELAY_COMMAND_INTRO_ESTABLISHED, - (char *) encoded_cell, encoded_len, - NULL); - /* On failure, the above function will close the circuit. */ - trn_cell_intro_established_free(cell); - tor_free(encoded_cell); - return ret; -} - -/** We received an ESTABLISH_INTRO <b>parsed_cell</b> on <b>circ</b>. It's - * well-formed and passed our verifications. Perform appropriate actions to - * establish an intro point. */ -static int -handle_verified_establish_intro_cell(or_circuit_t *circ, - const trn_cell_establish_intro_t *parsed_cell) -{ - /* Get the auth key of this intro point */ - ed25519_public_key_t auth_key; - get_auth_key_from_cell(&auth_key, RELAY_COMMAND_ESTABLISH_INTRO, - parsed_cell); - - /* Then notify the hidden service that the intro point is established by - sending an INTRO_ESTABLISHED cell */ - if (hs_intro_send_intro_established_cell(circ)) { - log_warn(LD_PROTOCOL, "Couldn't send INTRO_ESTABLISHED cell."); - return -1; - } - - /* Associate intro point auth key with this circuit. */ - hs_circuitmap_register_intro_circ_v3_relay_side(circ, &auth_key); - /* Repurpose this circuit into an intro circuit. */ - circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_INTRO_POINT); - - return 0; -} - -/** We just received an ESTABLISH_INTRO cell in <b>circ</b> with payload in - * <b>request</b>. Handle it by making <b>circ</b> an intro circuit. Return 0 - * if everything went well, or -1 if there were errors. */ -static int -handle_establish_intro(or_circuit_t *circ, const uint8_t *request, - size_t request_len) -{ - int cell_ok, retval = -1; - trn_cell_establish_intro_t *parsed_cell = NULL; - - tor_assert(circ); - tor_assert(request); - - log_info(LD_REND, "Received an ESTABLISH_INTRO request on circuit %" PRIu32, - circ->p_circ_id); - - /* Check that the circuit is in shape to become an intro point */ - if (!hs_intro_circuit_is_suitable_for_establish_intro(circ)) { - goto err; - } - - /* Parse the cell */ - ssize_t parsing_result = trn_cell_establish_intro_parse(&parsed_cell, - request, request_len); - if (parsing_result < 0) { - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, - "Rejecting %s ESTABLISH_INTRO cell.", - parsing_result == -1 ? "invalid" : "truncated"); - goto err; - } - - cell_ok = verify_establish_intro_cell(parsed_cell, - (uint8_t *) circ->rend_circ_nonce, - sizeof(circ->rend_circ_nonce)); - if (cell_ok < 0) { - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, - "Failed to verify ESTABLISH_INTRO cell."); - goto err; - } - - /* This cell is legit. Take the appropriate actions. */ - cell_ok = handle_verified_establish_intro_cell(circ, parsed_cell); - if (cell_ok < 0) { - goto err; - } - - /* We are done! */ - retval = 0; - goto done; - - err: - /* When sending the intro establish ack, on error the circuit can be marked - * as closed so avoid a double close. */ - if (!TO_CIRCUIT(circ)->marked_for_close) { - circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL); - } - - done: - trn_cell_establish_intro_free(parsed_cell); - return retval; -} - -/* Return True if circuit is suitable for being an intro circuit. */ -static int -circuit_is_suitable_intro_point(const or_circuit_t *circ, - const char *log_cell_type_str) -{ - tor_assert(circ); - tor_assert(log_cell_type_str); - - /* Basic circuit state sanity checks. */ - if (circ->base_.purpose != CIRCUIT_PURPOSE_OR) { - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, - "Rejecting %s on non-OR circuit.", log_cell_type_str); - return 0; - } - - if (circ->base_.n_chan) { - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, - "Rejecting %s on non-edge circuit.", log_cell_type_str); - return 0; - } - - /* Suitable. */ - return 1; -} - -/* Return True if circuit is suitable for being service-side intro circuit. */ -int -hs_intro_circuit_is_suitable_for_establish_intro(const or_circuit_t *circ) -{ - return circuit_is_suitable_intro_point(circ, "ESTABLISH_INTRO"); -} - -/* We just received an ESTABLISH_INTRO cell in <b>circ</b>. Figure out of it's - * a legacy or a next gen cell, and pass it to the appropriate handler. */ -int -hs_intro_received_establish_intro(or_circuit_t *circ, const uint8_t *request, - size_t request_len) -{ - tor_assert(circ); - tor_assert(request); - - if (request_len == 0) { - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, "Empty ESTABLISH_INTRO cell."); - goto err; - } - - /* Using the first byte of the cell, figure out the version of - * ESTABLISH_INTRO and pass it to the appropriate cell handler */ - const uint8_t first_byte = request[0]; - switch (first_byte) { - case HS_INTRO_AUTH_KEY_TYPE_LEGACY0: - case HS_INTRO_AUTH_KEY_TYPE_LEGACY1: - return rend_mid_establish_intro_legacy(circ, request, request_len); - case HS_INTRO_AUTH_KEY_TYPE_ED25519: - return handle_establish_intro(circ, request, request_len); - default: - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, - "Unrecognized AUTH_KEY_TYPE %u.", first_byte); - goto err; - } - - err: - circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL); - return -1; -} - -/* Send an INTRODUCE_ACK cell onto the circuit <b>circ</b> with the status - * value in <b>status</b>. Depending on the status, it can be ACK or a NACK. - * Return 0 on success else a negative value on error which will close the - * circuit. */ -static int -send_introduce_ack_cell(or_circuit_t *circ, hs_intro_ack_status_t status) -{ - int ret = -1; - uint8_t *encoded_cell = NULL; - ssize_t encoded_len, result_len; - trn_cell_introduce_ack_t *cell; - trn_cell_extension_t *ext; - - tor_assert(circ); - - /* Setup the INTRODUCE_ACK cell. We have no extensions so the N_EXTENSIONS - * field is set to 0 by default with a new object. */ - cell = trn_cell_introduce_ack_new(); - ret = trn_cell_introduce_ack_set_status(cell, status); - /* We have no cell extensions in an INTRODUCE_ACK cell. */ - ext = trn_cell_extension_new(); - trn_cell_extension_set_num(ext, 0); - trn_cell_introduce_ack_set_extensions(cell, ext); - /* A wrong status is a very bad code flow error as this value is controlled - * by the code in this file and not an external input. This means we use a - * code that is not known by the trunnel ABI. */ - tor_assert(ret == 0); - /* Encode the payload. We should never fail to get the encoded length. */ - encoded_len = trn_cell_introduce_ack_encoded_len(cell); - tor_assert(encoded_len > 0); - encoded_cell = tor_malloc_zero(encoded_len); - result_len = trn_cell_introduce_ack_encode(encoded_cell, encoded_len, cell); - tor_assert(encoded_len == result_len); - - ret = relay_send_command_from_edge(CONTROL_CELL_ID, TO_CIRCUIT(circ), - RELAY_COMMAND_INTRODUCE_ACK, - (char *) encoded_cell, encoded_len, - NULL); - /* On failure, the above function will close the circuit. */ - trn_cell_introduce_ack_free(cell); - tor_free(encoded_cell); - return ret; -} - -/* Validate a parsed INTRODUCE1 <b>cell</b>. Return 0 if valid or else a - * negative value for an invalid cell that should be NACKed. */ -STATIC int -validate_introduce1_parsed_cell(const trn_cell_introduce1_t *cell) -{ - size_t legacy_key_id_len; - const uint8_t *legacy_key_id; - - tor_assert(cell); - - /* This code path SHOULD NEVER be reached if the cell is a legacy type so - * safety net here. The legacy ID must be zeroes in this case. */ - legacy_key_id_len = trn_cell_introduce1_getlen_legacy_key_id(cell); - legacy_key_id = trn_cell_introduce1_getconstarray_legacy_key_id(cell); - if (BUG(!tor_mem_is_zero((char *) legacy_key_id, legacy_key_id_len))) { - goto invalid; - } - - /* The auth key of an INTRODUCE1 should be of type ed25519 thus leading to a - * known fixed length as well. */ - if (trn_cell_introduce1_get_auth_key_type(cell) != - HS_INTRO_AUTH_KEY_TYPE_ED25519) { - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, - "Rejecting invalid INTRODUCE1 cell auth key type. " - "Responding with NACK."); - goto invalid; - } - if (trn_cell_introduce1_get_auth_key_len(cell) != ED25519_PUBKEY_LEN || - trn_cell_introduce1_getlen_auth_key(cell) != ED25519_PUBKEY_LEN) { - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, - "Rejecting invalid INTRODUCE1 cell auth key length. " - "Responding with NACK."); - goto invalid; - } - if (trn_cell_introduce1_getlen_encrypted(cell) == 0) { - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, - "Rejecting invalid INTRODUCE1 cell encrypted length. " - "Responding with NACK."); - goto invalid; - } - - return 0; - invalid: - return -1; -} - -/* We just received a non legacy INTRODUCE1 cell on <b>client_circ</b> with - * the payload in <b>request</b> of size <b>request_len</b>. Return 0 if - * everything went well, or -1 if an error occurred. This function is in charge - * of sending back an INTRODUCE_ACK cell and will close client_circ on error. - */ -STATIC int -handle_introduce1(or_circuit_t *client_circ, const uint8_t *request, - size_t request_len) -{ - int ret = -1; - or_circuit_t *service_circ; - trn_cell_introduce1_t *parsed_cell; - hs_intro_ack_status_t status = HS_INTRO_ACK_STATUS_SUCCESS; - - tor_assert(client_circ); - tor_assert(request); - - /* Parse cell. Note that we can only parse the non encrypted section for - * which we'll use the authentication key to find the service introduction - * circuit and relay the cell on it. */ - ssize_t cell_size = trn_cell_introduce1_parse(&parsed_cell, request, - request_len); - if (cell_size < 0) { - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, - "Rejecting %s INTRODUCE1 cell. Responding with NACK.", - cell_size == -1 ? "invalid" : "truncated"); - /* Inform client that the INTRODUCE1 has a bad format. */ - status = HS_INTRO_ACK_STATUS_BAD_FORMAT; - goto send_ack; - } - - /* Once parsed validate the cell format. */ - if (validate_introduce1_parsed_cell(parsed_cell) < 0) { - /* Inform client that the INTRODUCE1 has bad format. */ - status = HS_INTRO_ACK_STATUS_BAD_FORMAT; - goto send_ack; - } - - /* Find introduction circuit through our circuit map. */ - { - ed25519_public_key_t auth_key; - get_auth_key_from_cell(&auth_key, RELAY_COMMAND_INTRODUCE1, parsed_cell); - service_circ = hs_circuitmap_get_intro_circ_v3_relay_side(&auth_key); - if (service_circ == NULL) { - char b64_key[ED25519_BASE64_LEN + 1]; - ed25519_public_to_base64(b64_key, &auth_key); - log_info(LD_REND, "No intro circuit found for INTRODUCE1 cell " - "with auth key %s from circuit %" PRIu32 ". " - "Responding with NACK.", - safe_str(b64_key), client_circ->p_circ_id); - /* Inform the client that we don't know the requested service ID. */ - status = HS_INTRO_ACK_STATUS_UNKNOWN_ID; - goto send_ack; - } - } - - /* Relay the cell to the service on its intro circuit with an INTRODUCE2 - * cell which is the same exact payload. */ - if (relay_send_command_from_edge(CONTROL_CELL_ID, TO_CIRCUIT(service_circ), - RELAY_COMMAND_INTRODUCE2, - (char *) request, request_len, NULL)) { - log_warn(LD_PROTOCOL, "Unable to send INTRODUCE2 cell to the service."); - /* Inform the client that we can't relay the cell. */ - status = HS_INTRO_ACK_STATUS_CANT_RELAY; - goto send_ack; - } - - /* Success! Send an INTRODUCE_ACK success status onto the client circuit. */ - status = HS_INTRO_ACK_STATUS_SUCCESS; - ret = 0; - - send_ack: - /* Send INTRODUCE_ACK or INTRODUCE_NACK to client */ - if (send_introduce_ack_cell(client_circ, status) < 0) { - log_warn(LD_PROTOCOL, "Unable to send an INTRODUCE ACK status %d " - "to client.", status); - /* Circuit has been closed on failure of transmission. */ - goto done; - } - if (status != HS_INTRO_ACK_STATUS_SUCCESS) { - /* We just sent a NACK that is a non success status code so close the - * circuit because it's not useful to keep it open. Remember, a client can - * only send one INTRODUCE1 cell on a circuit. */ - circuit_mark_for_close(TO_CIRCUIT(client_circ), END_CIRC_REASON_INTERNAL); - } - done: - trn_cell_introduce1_free(parsed_cell); - return ret; -} - -/* Identify if the encoded cell we just received is a legacy one or not. The - * <b>request</b> should be at least DIGEST_LEN bytes long. */ -STATIC int -introduce1_cell_is_legacy(const uint8_t *request) -{ - tor_assert(request); - - /* If the first 20 bytes of the cell (DIGEST_LEN) are NOT zeroes, it - * indicates a legacy cell (v2). */ - if (!tor_mem_is_zero((const char *) request, DIGEST_LEN)) { - /* Legacy cell. */ - return 1; - } - /* Not a legacy cell. */ - return 0; -} - -/* Return true iff the circuit <b>circ</b> is suitable for receiving an - * INTRODUCE1 cell. */ -STATIC int -circuit_is_suitable_for_introduce1(const or_circuit_t *circ) -{ - tor_assert(circ); - - /* Is this circuit an intro point circuit? */ - if (!circuit_is_suitable_intro_point(circ, "INTRODUCE1")) { - return 0; - } - - if (circ->already_received_introduce1) { - log_fn(LOG_PROTOCOL_WARN, LD_REND, - "Blocking multiple introductions on the same circuit. " - "Someone might be trying to attack a hidden service through " - "this relay."); - return 0; - } - - return 1; -} - -/* We just received an INTRODUCE1 cell on <b>circ</b>. Figure out which type - * it is and pass it to the appropriate handler. Return 0 on success else a - * negative value and the circuit is closed. */ -int -hs_intro_received_introduce1(or_circuit_t *circ, const uint8_t *request, - size_t request_len) -{ - int ret; - - tor_assert(circ); - tor_assert(request); - - /* A cell that can't hold a DIGEST_LEN is invalid as we need to check if - * it's a legacy cell or not using the first DIGEST_LEN bytes. */ - if (request_len < DIGEST_LEN) { - log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, "Invalid INTRODUCE1 cell length."); - goto err; - } - - /* Make sure we have a circuit that can have an INTRODUCE1 cell on it. */ - if (!circuit_is_suitable_for_introduce1(circ)) { - /* We do not send a NACK because the circuit is not suitable for any kind - * of response or transmission as it's a violation of the protocol. */ - goto err; - } - /* Mark the circuit that we got this cell. None are allowed after this as a - * DoS mitigation since one circuit with one client can hammer a service. */ - circ->already_received_introduce1 = 1; - - /* We are sure here to have at least DIGEST_LEN bytes. */ - if (introduce1_cell_is_legacy(request)) { - /* Handle a legacy cell. */ - ret = rend_mid_introduce_legacy(circ, request, request_len); - } else { - /* Handle a non legacy cell. */ - ret = handle_introduce1(circ, request, request_len); - } - return ret; - - err: - circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL); - return -1; -} - -/* Clear memory allocated by the given intropoint object ip (but don't free the - * object itself). */ -void -hs_intropoint_clear(hs_intropoint_t *ip) -{ - if (ip == NULL) { - return; - } - tor_cert_free(ip->auth_key_cert); - SMARTLIST_FOREACH(ip->link_specifiers, hs_desc_link_specifier_t *, ls, - hs_desc_link_specifier_free(ls)); - smartlist_free(ip->link_specifiers); - memset(ip, 0, sizeof(hs_intropoint_t)); -} |