diff options
Diffstat (limited to 'src/feature/rend/rendmid.c')
| -rw-r--r-- | src/feature/rend/rendmid.c | 370 |
1 files changed, 370 insertions, 0 deletions
diff --git a/src/feature/rend/rendmid.c b/src/feature/rend/rendmid.c new file mode 100644 index 0000000000..0fd6516eaa --- /dev/null +++ b/src/feature/rend/rendmid.c @@ -0,0 +1,370 @@ +/* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. + * Copyright (c) 2007-2018, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file rendmid.c + * \brief Implement introductions points and rendezvous points. + **/ + +#include "core/or/or.h" +#include "core/or/channel.h" +#include "core/or/circuitlist.h" +#include "core/or/circuituse.h" +#include "app/config/config.h" +#include "lib/crypt_ops/crypto.h" +#include "core/or/dos.h" +#include "core/or/relay.h" +#include "feature/rend/rendmid.h" +#include "feature/stats/rephist.h" +#include "feature/hs/hs_circuitmap.h" +#include "feature/hs/hs_intropoint.h" + +#include "core/or/or_circuit_st.h" + +/** Respond to an ESTABLISH_INTRO cell by checking the signed data and + * setting the circuit's purpose and service pk digest. + */ +int +rend_mid_establish_intro_legacy(or_circuit_t *circ, const uint8_t *request, + size_t request_len) +{ + crypto_pk_t *pk = NULL; + char buf[DIGEST_LEN+9]; + char expected_digest[DIGEST_LEN]; + char pk_digest[DIGEST_LEN]; + size_t asn1len; + or_circuit_t *c; + char serviceid[REND_SERVICE_ID_LEN_BASE32+1]; + int reason = END_CIRC_REASON_INTERNAL; + + log_info(LD_REND, + "Received a legacy ESTABLISH_INTRO request on circuit %u", + (unsigned) circ->p_circ_id); + + if (!hs_intro_circuit_is_suitable_for_establish_intro(circ)) { + reason = END_CIRC_REASON_TORPROTOCOL; + goto err; + } + + if (request_len < 2+DIGEST_LEN) + goto truncated; + /* First 2 bytes: length of asn1-encoded key. */ + asn1len = ntohs(get_uint16(request)); + + /* Next asn1len bytes: asn1-encoded key. */ + if (request_len < 2+DIGEST_LEN+asn1len) + goto truncated; + pk = crypto_pk_asn1_decode((char*)(request+2), asn1len); + if (!pk) { + reason = END_CIRC_REASON_TORPROTOCOL; + log_warn(LD_PROTOCOL, "Couldn't decode public key."); + goto err; + } + + /* Next 20 bytes: Hash of rend_circ_nonce | "INTRODUCE" */ + memcpy(buf, circ->rend_circ_nonce, DIGEST_LEN); + memcpy(buf+DIGEST_LEN, "INTRODUCE", 9); + if (crypto_digest(expected_digest, buf, DIGEST_LEN+9) < 0) { + log_warn(LD_BUG, "Internal error computing digest."); + goto err; + } + if (tor_memneq(expected_digest, request+2+asn1len, DIGEST_LEN)) { + log_warn(LD_PROTOCOL, "Hash of session info was not as expected."); + reason = END_CIRC_REASON_TORPROTOCOL; + goto err; + } + /* Rest of body: signature of previous data */ + if (crypto_pk_public_checksig_digest(pk, + (char*)request, 2+asn1len+DIGEST_LEN, + (char*)(request+2+DIGEST_LEN+asn1len), + request_len-(2+DIGEST_LEN+asn1len))<0) { + log_warn(LD_PROTOCOL, + "Incorrect signature on ESTABLISH_INTRO cell; rejecting."); + reason = END_CIRC_REASON_TORPROTOCOL; + goto err; + } + + /* The request is valid. First, compute the hash of the service's PK.*/ + if (crypto_pk_get_digest(pk, pk_digest)<0) { + log_warn(LD_BUG, "Internal error: couldn't hash public key."); + goto err; + } + + crypto_pk_free(pk); /* don't need it anymore */ + pk = NULL; /* so we don't free it again if err */ + + base32_encode(serviceid, REND_SERVICE_ID_LEN_BASE32+1, + pk_digest, REND_SERVICE_ID_LEN); + + /* Close any other intro circuits with the same pk. */ + c = NULL; + while ((c = hs_circuitmap_get_intro_circ_v2_relay_side( + (const uint8_t *)pk_digest))) { + log_info(LD_REND, "Replacing old circuit for service %s", + safe_str(serviceid)); + circuit_mark_for_close(TO_CIRCUIT(c), END_CIRC_REASON_FINISHED); + /* Now it's marked, and it won't be returned next time. */ + } + + /* Acknowledge the request. */ + if (hs_intro_send_intro_established_cell(circ) < 0) { + log_info(LD_GENERAL, "Couldn't send INTRO_ESTABLISHED cell."); + goto err_no_close; + } + + /* Now, set up this circuit. */ + circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_INTRO_POINT); + hs_circuitmap_register_intro_circ_v2_relay_side(circ, (uint8_t *)pk_digest); + + log_info(LD_REND, + "Established introduction point on circuit %u for service %s", + (unsigned) circ->p_circ_id, safe_str(serviceid)); + + return 0; + truncated: + log_warn(LD_PROTOCOL, "Rejecting truncated ESTABLISH_INTRO cell."); + reason = END_CIRC_REASON_TORPROTOCOL; + err: + circuit_mark_for_close(TO_CIRCUIT(circ), reason); + err_no_close: + if (pk) crypto_pk_free(pk); + return -1; +} + +/** Process an INTRODUCE1 cell by finding the corresponding introduction + * circuit, and relaying the body of the INTRODUCE1 cell inside an + * INTRODUCE2 cell. + */ +int +rend_mid_introduce_legacy(or_circuit_t *circ, const uint8_t *request, + size_t request_len) +{ + or_circuit_t *intro_circ; + char serviceid[REND_SERVICE_ID_LEN_BASE32+1]; + char nak_body[1]; + + log_info(LD_REND, "Received an INTRODUCE1 request on circuit %u", + (unsigned)circ->p_circ_id); + + /* At this point, we know that the circuit is valid for an INTRODUCE1 + * because the validation has been made before calling this function. */ + tor_assert(circ->base_.purpose == CIRCUIT_PURPOSE_OR); + tor_assert(!circ->base_.n_chan); + + /* We could change this to MAX_HEX_NICKNAME_LEN now that 0.0.9.x is + * obsolete; however, there isn't much reason to do so, and we're going + * to revise this protocol anyway. + */ + if (request_len < (DIGEST_LEN+(MAX_NICKNAME_LEN+1)+REND_COOKIE_LEN+ + DH1024_KEY_LEN+CIPHER_KEY_LEN+ + PKCS1_OAEP_PADDING_OVERHEAD)) { + log_warn(LD_PROTOCOL, "Impossibly short INTRODUCE1 cell on circuit %u; " + "responding with nack.", + (unsigned)circ->p_circ_id); + goto err; + } + + base32_encode(serviceid, REND_SERVICE_ID_LEN_BASE32+1, + (char*)request, REND_SERVICE_ID_LEN); + + /* The first 20 bytes are all we look at: they have a hash of the service's + * PK. */ + intro_circ = hs_circuitmap_get_intro_circ_v2_relay_side( + (const uint8_t*)request); + if (!intro_circ) { + log_info(LD_REND, + "No intro circ found for INTRODUCE1 cell (%s) from circuit %u; " + "responding with nack.", + safe_str(serviceid), (unsigned)circ->p_circ_id); + goto err; + } + + log_info(LD_REND, + "Sending introduction request for service %s " + "from circ %u to circ %u", + safe_str(serviceid), (unsigned)circ->p_circ_id, + (unsigned)intro_circ->p_circ_id); + + /* Great. Now we just relay the cell down the circuit. */ + if (relay_send_command_from_edge(0, TO_CIRCUIT(intro_circ), + RELAY_COMMAND_INTRODUCE2, + (char*)request, request_len, NULL)) { + log_warn(LD_GENERAL, + "Unable to send INTRODUCE2 cell to Tor client."); + /* Stop right now, the circuit has been closed. */ + return -1; + } + /* And send an ack down the client's circuit. Empty body means succeeded. */ + if (relay_send_command_from_edge(0,TO_CIRCUIT(circ), + RELAY_COMMAND_INTRODUCE_ACK, + NULL,0,NULL)) { + log_warn(LD_GENERAL, "Unable to send INTRODUCE_ACK cell to Tor client."); + /* Stop right now, the circuit has been closed. */ + return -1; + } + + return 0; + err: + /* Send the client a NACK */ + nak_body[0] = 1; + if (relay_send_command_from_edge(0,TO_CIRCUIT(circ), + RELAY_COMMAND_INTRODUCE_ACK, + nak_body, 1, NULL)) { + log_warn(LD_GENERAL, "Unable to send NAK to Tor client."); + } + return -1; +} + +/** Process an ESTABLISH_RENDEZVOUS cell by setting the circuit's purpose and + * rendezvous cookie. + */ +int +rend_mid_establish_rendezvous(or_circuit_t *circ, const uint8_t *request, + size_t request_len) +{ + char hexid[9]; + int reason = END_CIRC_REASON_TORPROTOCOL; + + log_info(LD_REND, "Received an ESTABLISH_RENDEZVOUS request on circuit %u", + (unsigned)circ->p_circ_id); + + if (circ->base_.purpose != CIRCUIT_PURPOSE_OR) { + log_warn(LD_PROTOCOL, + "Tried to establish rendezvous on non-OR circuit with purpose %s", + circuit_purpose_to_string(circ->base_.purpose)); + goto err; + } + + /* Check if we are configured to accept established rendezvous cells from + * client or in other words Tor2Web clients. */ + if (channel_is_client(circ->p_chan) && + dos_should_refuse_single_hop_client()) { + /* Note it down for the heartbeat log purposes. */ + dos_note_refuse_single_hop_client(); + /* Silent drop so the client has to time out before moving on. */ + return 0; + } + + if (circ->base_.n_chan) { + log_warn(LD_PROTOCOL, + "Tried to establish rendezvous on non-edge circuit"); + goto err; + } + + if (request_len != REND_COOKIE_LEN) { + log_fn(LOG_PROTOCOL_WARN, + LD_PROTOCOL, "Invalid length on ESTABLISH_RENDEZVOUS."); + goto err; + } + + if (hs_circuitmap_get_rend_circ_relay_side(request)) { + log_warn(LD_PROTOCOL, + "Duplicate rendezvous cookie in ESTABLISH_RENDEZVOUS."); + goto err; + } + + /* Acknowledge the request. */ + if (relay_send_command_from_edge(0,TO_CIRCUIT(circ), + RELAY_COMMAND_RENDEZVOUS_ESTABLISHED, + "", 0, NULL)<0) { + log_warn(LD_PROTOCOL, "Couldn't send RENDEZVOUS_ESTABLISHED cell."); + /* Stop right now, the circuit has been closed. */ + return -1; + } + + circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_REND_POINT_WAITING); + hs_circuitmap_register_rend_circ_relay_side(circ, request); + + base16_encode(hexid,9,(char*)request,4); + + log_info(LD_REND, + "Established rendezvous point on circuit %u for cookie %s", + (unsigned)circ->p_circ_id, hexid); + + return 0; + err: + circuit_mark_for_close(TO_CIRCUIT(circ), reason); + return -1; +} + +/** Process a RENDEZVOUS1 cell by looking up the correct rendezvous + * circuit by its relaying the cell's body in a RENDEZVOUS2 cell, and + * connecting the two circuits. + */ +int +rend_mid_rendezvous(or_circuit_t *circ, const uint8_t *request, + size_t request_len) +{ + const or_options_t *options = get_options(); + or_circuit_t *rend_circ; + char hexid[9]; + int reason = END_CIRC_REASON_INTERNAL; + + if (circ->base_.purpose != CIRCUIT_PURPOSE_OR || circ->base_.n_chan) { + log_info(LD_REND, + "Tried to complete rendezvous on non-OR or non-edge circuit %u.", + (unsigned)circ->p_circ_id); + reason = END_CIRC_REASON_TORPROTOCOL; + goto err; + } + + if (request_len < REND_COOKIE_LEN) { + log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, + "Rejecting RENDEZVOUS1 cell with bad length (%d) on circuit %u.", + (int)request_len, (unsigned)circ->p_circ_id); + reason = END_CIRC_REASON_TORPROTOCOL; + goto err; + } + + base16_encode(hexid, sizeof(hexid), (const char*)request, 4); + + log_info(LD_REND, + "Got request for rendezvous from circuit %u to cookie %s.", + (unsigned)circ->p_circ_id, hexid); + + rend_circ = hs_circuitmap_get_rend_circ_relay_side(request); + if (!rend_circ) { + log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, + "Rejecting RENDEZVOUS1 cell with unrecognized rendezvous cookie %s.", + hexid); + reason = END_CIRC_REASON_TORPROTOCOL; + goto err; + } + + /* Statistics: Mark this circuit as an RP circuit so that we collect + stats from it. */ + if (options->HiddenServiceStatistics) { + circ->circuit_carries_hs_traffic_stats = 1; + } + + /* Send the RENDEZVOUS2 cell to the client. */ + if (relay_send_command_from_edge(0, TO_CIRCUIT(rend_circ), + RELAY_COMMAND_RENDEZVOUS2, + (char*)(request+REND_COOKIE_LEN), + request_len-REND_COOKIE_LEN, NULL)) { + log_warn(LD_GENERAL, + "Unable to send RENDEZVOUS2 cell to client on circuit %u.", + (unsigned)rend_circ->p_circ_id); + /* Stop right now, the circuit has been closed. */ + return -1; + } + + /* Join the circuits. */ + log_info(LD_REND, + "Completing rendezvous: circuit %u joins circuit %u (cookie %s)", + (unsigned)circ->p_circ_id, (unsigned)rend_circ->p_circ_id, hexid); + + circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_REND_ESTABLISHED); + circuit_change_purpose(TO_CIRCUIT(rend_circ), + CIRCUIT_PURPOSE_REND_ESTABLISHED); + hs_circuitmap_remove_circuit(TO_CIRCUIT(circ)); + + rend_circ->rend_splice = circ; + circ->rend_splice = rend_circ; + + return 0; + err: + circuit_mark_for_close(TO_CIRCUIT(circ), reason); + return -1; +} |