Commit 0cb66fc9 authored by David Goulet's avatar David Goulet Committed by Nick Mathewson

prop224: Introduce e2e rendezvous circuit code.

This commit adds most of the work of #21859. It introduces hs_circuit.c
functions that can handle the setup of e2e circuits for prop224 hidden
services, and also for legacy hidden service clients. Entry points are:

		prop224 circuits: hs_circuit_setup_e2e_rend_circ()
		legacy client-side circuits: hs_circuit_setup_e2e_rend_circ_legacy_client()

This commit swaps the old rendclient code to use the new API.

I didn't try to accomodate the legacy service-side code in this API, since
that's too tangled up and it would mess up the new API considerably IMO (all
this service_pending_final_cpath_ref stuff is complicated and I didn't want to
change it).
Signed-off-by: David Goulet's avatarDavid Goulet <dgoulet@torproject.org>
parent 0b2018a4
/* Copyright (c) 2017, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file hs_circuit.c
**/
#include "or.h"
#include "circuitbuild.h"
#include "circuitlist.h"
#include "circuituse.h"
#include "config.h"
#include "hs_circuit.h"
#include "hs_ident.h"
#include "hs_ntor.h"
/* A circuit is about to become an e2e rendezvous circuit. Check
* <b>circ_purpose</b> and ensure that it's properly set. Return 0 if circuit
* purpose is properly set, otherwise return -1. */
static int
rend_circuit_validate_purpose(unsigned int circ_purpose, int is_service_side)
{
if (is_service_side) {
if (circ_purpose != CIRCUIT_PURPOSE_S_CONNECT_REND) {
log_warn(LD_GENERAL, "HS e2e circuit setup with wrong purpose(%d)",
circ_purpose);
return -1;
}
}
if (!is_service_side) {
if (circ_purpose != CIRCUIT_PURPOSE_C_REND_READY &&
circ_purpose != CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED) {
log_warn(LD_GENERAL, "Client e2e circuit setup with wrong purpose(%d)",
circ_purpose);
return -1;
}
}
return 0;
}
/* Create and return a crypt path for the final hop of a v3 prop224 rendezvous
* circuit. Initialize the crypt path crypto using the output material from the
* ntor key exchange at <b>ntor_key_seed</b>.
*
* If <b>is_service_side</b> is set, we are the hidden service and the final
* hop of the rendezvous circuit is the client on the other side. */
static crypt_path_t *
get_rend_cpath(const uint8_t *ntor_key_seed, int is_service_side)
{
uint8_t keys[HS_NTOR_KEY_EXPANSION_KDF_OUT_LEN];
crypt_path_t *cpath = NULL;
/* Do the key expansion */
hs_ntor_circuit_key_expansion(ntor_key_seed, keys);
/* Setup the cpath */
cpath = tor_malloc_zero(sizeof(crypt_path_t));
cpath->magic = CRYPT_PATH_MAGIC;
if (circuit_init_cpath_crypto(cpath, (char*)keys,
is_service_side, 1) < 0) {
tor_free(cpath);
goto err;
}
err:
memwipe(keys, 0, sizeof(keys));
return cpath;
}
/* We are a v2 legacy HS client: Create and return a crypt path for the hidden
* service on the other side of the rendezvous circuit <b>circ</b>. Initialize
* the crypt path crypto using the body of the RENDEZVOUS1 cell at
* <b>rend_cell_body</b> (which must be at least DH_KEY_LEN+DIGEST_LEN bytes).
*/
static crypt_path_t *
get_rend_cpath_legacy(origin_circuit_t *circ, const uint8_t *rend_cell_body)
{
crypt_path_t *hop = NULL;
char keys[DIGEST_LEN+CPATH_KEY_MATERIAL_LEN];
/* first DH_KEY_LEN bytes are g^y from the service. Finish the dh
* handshake...*/
tor_assert(circ->build_state);
tor_assert(circ->build_state->pending_final_cpath);
hop = circ->build_state->pending_final_cpath;
tor_assert(hop->rend_dh_handshake_state);
if (crypto_dh_compute_secret(LOG_PROTOCOL_WARN, hop->rend_dh_handshake_state,
(char*)rend_cell_body, DH_KEY_LEN,
keys, DIGEST_LEN+CPATH_KEY_MATERIAL_LEN)<0) {
log_warn(LD_GENERAL, "Couldn't complete DH handshake.");
goto err;
}
/* ... and set up cpath. */
if (circuit_init_cpath_crypto(hop, keys+DIGEST_LEN, 0, 0)<0)
goto err;
/* Check whether the digest is right... */
if (tor_memneq(keys, rend_cell_body+DH_KEY_LEN, DIGEST_LEN)) {
log_warn(LD_PROTOCOL, "Incorrect digest of key material.");
goto err;
}
/* clean up the crypto stuff we just made */
crypto_dh_free(hop->rend_dh_handshake_state);
hop->rend_dh_handshake_state = NULL;
goto done;
err:
hop = NULL;
done:
memwipe(keys, 0, sizeof(keys));
return hop;
}
/* Append the final <b>hop</b> to the cpath of the rend <b>circ</b>, and mark
* <b>circ</b> ready for use to transfer HS relay cells. */
static void
finalize_rend_circuit(origin_circuit_t *circ, crypt_path_t *hop,
int is_service_side)
{
tor_assert(circ);
tor_assert(hop);
/* Notify the circuit state machine that we are splicing this circuit */
int new_circ_purpose = is_service_side ?
CIRCUIT_PURPOSE_S_REND_JOINED : CIRCUIT_PURPOSE_C_REND_JOINED;
circuit_change_purpose(TO_CIRCUIT(circ), new_circ_purpose);
/* All is well. Extend the circuit. */
hop->state = CPATH_STATE_OPEN;
/* Set the windows to default. These are the windows that the client thinks
* the service has. */
hop->package_window = circuit_initial_package_window();
hop->deliver_window = CIRCWINDOW_START;
/* Now that this circuit has finished connecting to its destination,
* make sure circuit_get_open_circ_or_launch is willing to return it
* so we can actually use it. */
circ->hs_circ_has_timed_out = 0;
/* Append the hop to the cpath of this circuit */
onion_append_to_cpath(&circ->cpath, hop);
/* In legacy code, 'pending_final_cpath' points to the final hop we just
* appended to the cpath. We set the original pointer to NULL so that we
* don't double free it. */
if (circ->build_state) {
circ->build_state->pending_final_cpath = NULL;
}
/* Finally, mark circuit as ready to be used for client streams */
if (!is_service_side) {
circuit_try_attaching_streams(circ);
}
}
/* Circuit <b>circ</b> just finished the rend ntor key exchange. Use the key
* exchange output material at <b>ntor_key_seed</b> and setup <b>circ</b> to
* serve as a rendezvous end-to-end circuit between the client and the
* service. If <b>is_service_side</b> is set, then we are the hidden service
* and the other side is the client.
*
* Return 0 if the operation went well; in case of error return -1. */
int
hs_circuit_setup_e2e_rend_circ(origin_circuit_t *circ,
const uint8_t *ntor_key_seed,
int is_service_side)
{
if (BUG(rend_circuit_validate_purpose(TO_CIRCUIT(circ)->purpose,
is_service_side)) < 0) {
return -1;
}
crypt_path_t *hop = get_rend_cpath(ntor_key_seed, is_service_side);
if (!hop) {
log_warn(LD_REND, "Couldn't get v3 %s cpath!",
is_service_side ? "service-side" : "client-side");
return -1;
}
finalize_rend_circuit(circ, hop, is_service_side);
return 0;
}
/* We are a v2 legacy HS client and we just received a RENDEZVOUS1 cell
* <b>rend_cell_body</b> on <b>circ</b>. Finish up the DH key exchange and then
* extend the crypt path of <b>circ</b> so that the hidden service is on the
* other side. */
int
hs_circuit_setup_e2e_rend_circ_legacy_client(origin_circuit_t *circ,
const uint8_t *rend_cell_body)
{
if (BUG(rend_circuit_validate_purpose(TO_CIRCUIT(circ)->purpose, 0)) < 0) {
return -1;
}
crypt_path_t *hop = get_rend_cpath_legacy(circ, rend_cell_body);
if (!hop) {
log_warn(LD_GENERAL, "Couldn't get v2 cpath.");
return -1;
}
finalize_rend_circuit(circ, hop, 0);
return 0;
}
/* Copyright (c) 2017, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file hs_circuit.h
* \brief Header file containing circuit data for the whole HS subsytem.
**/
#ifndef TOR_HS_CIRCUIT_H
#define TOR_HS_CIRCUIT_H
#include "or.h"
/* e2e circuit API. */
int hs_circuit_setup_e2e_rend_circ(origin_circuit_t *circ,
const uint8_t *ntor_key_seed,
int is_service_side);
int hs_circuit_setup_e2e_rend_circ_legacy_client(origin_circuit_t *circ,
const uint8_t *rend_cell_body);
#endif /* TOR_HS_CIRCUIT_H */
......@@ -53,6 +53,7 @@ LIBTOR_A_SOURCES = \
src/or/hs_cache.c \
src/or/hs_circuitmap.c \
src/or/hs_common.c \
src/or/hs_circuit.c \
src/or/hs_descriptor.c \
src/or/hs_ident.c \
src/or/hs_intropoint.c \
......@@ -182,6 +183,7 @@ ORHEADERS = \
src/or/hibernate.h \
src/or/hs_cache.h \
src/or/hs_common.h \
src/or/hs_circuit.h \
src/or/hs_descriptor.h \
src/or/hs_ident.h \
src/or/hs_intropoint.h \
......
......@@ -17,6 +17,7 @@
#include "connection_edge.h"
#include "directory.h"
#include "hs_common.h"
#include "hs_circuit.h"
#include "main.h"
#include "networkstatus.h"
#include "nodelist.h"
......@@ -1150,9 +1151,6 @@ int
rend_client_receive_rendezvous(origin_circuit_t *circ, const uint8_t *request,
size_t request_len)
{
crypt_path_t *hop;
char keys[DIGEST_LEN+CPATH_KEY_MATERIAL_LEN];
if ((circ->base_.purpose != CIRCUIT_PURPOSE_C_REND_READY &&
circ->base_.purpose != CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED)
|| !circ->build_state->pending_final_cpath) {
......@@ -1170,55 +1168,13 @@ rend_client_receive_rendezvous(origin_circuit_t *circ, const uint8_t *request,
log_info(LD_REND,"Got RENDEZVOUS2 cell from hidden service.");
/* first DH_KEY_LEN bytes are g^y from the service. Finish the dh
* handshake...*/
tor_assert(circ->build_state);
tor_assert(circ->build_state->pending_final_cpath);
hop = circ->build_state->pending_final_cpath;
tor_assert(hop->rend_dh_handshake_state);
if (crypto_dh_compute_secret(LOG_PROTOCOL_WARN,
hop->rend_dh_handshake_state, (char*)request,
DH_KEY_LEN,
keys, DIGEST_LEN+CPATH_KEY_MATERIAL_LEN)<0) {
log_warn(LD_GENERAL, "Couldn't complete DH handshake.");
if (hs_circuit_setup_e2e_rend_circ_legacy_client(circ, request) < 0) {
log_warn(LD_GENERAL, "Failed to setup circ");
goto err;
}
/* ... and set up cpath. */
if (circuit_init_cpath_crypto(hop, keys+DIGEST_LEN, 0, 0)<0)
goto err;
/* Check whether the digest is right... */
if (tor_memneq(keys, request+DH_KEY_LEN, DIGEST_LEN)) {
log_warn(LD_PROTOCOL, "Incorrect digest of key material.");
goto err;
}
crypto_dh_free(hop->rend_dh_handshake_state);
hop->rend_dh_handshake_state = NULL;
/* All is well. Extend the circuit. */
circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_C_REND_JOINED);
hop->state = CPATH_STATE_OPEN;
/* set the windows to default. these are the windows
* that the client thinks the service has.
*/
hop->package_window = circuit_initial_package_window();
hop->deliver_window = CIRCWINDOW_START;
/* Now that this circuit has finished connecting to its destination,
* make sure circuit_get_open_circ_or_launch is willing to return it
* so we can actually use it. */
circ->hs_circ_has_timed_out = 0;
onion_append_to_cpath(&circ->cpath, hop);
circ->build_state->pending_final_cpath = NULL; /* prevent double-free */
circuit_try_attaching_streams(circ);
memwipe(keys, 0, sizeof(keys));
return 0;
err:
memwipe(keys, 0, sizeof(keys));
circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);
return -1;
}
......
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