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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 <dgoulet@torproject.org>
This commit is contained in:
David Goulet
Nick Mathewson
parent
0b2018a4d0
commit
0cb66fc900
4 changed files with 244 additions and 48 deletions
215
src/or/hs_circuit.c
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215
src/or/hs_circuit.c
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@ -0,0 +1,215 @@
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/* Copyright (c) 2017, The Tor Project, Inc. */
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/* See LICENSE for licensing information */
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/**
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* \file hs_circuit.c
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**/
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#include "or.h"
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#include "circuitbuild.h"
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#include "circuitlist.h"
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#include "circuituse.h"
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#include "config.h"
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#include "hs_circuit.h"
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#include "hs_ident.h"
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#include "hs_ntor.h"
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/* A circuit is about to become an e2e rendezvous circuit. Check
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* <b>circ_purpose</b> and ensure that it's properly set. Return 0 if circuit
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* purpose is properly set, otherwise return -1. */
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static int
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rend_circuit_validate_purpose(unsigned int circ_purpose, int is_service_side)
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{
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if (is_service_side) {
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if (circ_purpose != CIRCUIT_PURPOSE_S_CONNECT_REND) {
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log_warn(LD_GENERAL, "HS e2e circuit setup with wrong purpose(%d)",
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circ_purpose);
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return -1;
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}
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}
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if (!is_service_side) {
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if (circ_purpose != CIRCUIT_PURPOSE_C_REND_READY &&
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circ_purpose != CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED) {
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log_warn(LD_GENERAL, "Client e2e circuit setup with wrong purpose(%d)",
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circ_purpose);
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return -1;
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}
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}
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return 0;
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}
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/* Create and return a crypt path for the final hop of a v3 prop224 rendezvous
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* circuit. Initialize the crypt path crypto using the output material from the
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* ntor key exchange at <b>ntor_key_seed</b>.
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*
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* If <b>is_service_side</b> is set, we are the hidden service and the final
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* hop of the rendezvous circuit is the client on the other side. */
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static crypt_path_t *
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get_rend_cpath(const uint8_t *ntor_key_seed, int is_service_side)
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{
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uint8_t keys[HS_NTOR_KEY_EXPANSION_KDF_OUT_LEN];
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crypt_path_t *cpath = NULL;
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/* Do the key expansion */
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hs_ntor_circuit_key_expansion(ntor_key_seed, keys);
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/* Setup the cpath */
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cpath = tor_malloc_zero(sizeof(crypt_path_t));
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cpath->magic = CRYPT_PATH_MAGIC;
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if (circuit_init_cpath_crypto(cpath, (char*)keys,
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is_service_side, 1) < 0) {
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tor_free(cpath);
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goto err;
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}
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err:
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memwipe(keys, 0, sizeof(keys));
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return cpath;
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}
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/* We are a v2 legacy HS client: Create and return a crypt path for the hidden
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* service on the other side of the rendezvous circuit <b>circ</b>. Initialize
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* the crypt path crypto using the body of the RENDEZVOUS1 cell at
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* <b>rend_cell_body</b> (which must be at least DH_KEY_LEN+DIGEST_LEN bytes).
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*/
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static crypt_path_t *
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get_rend_cpath_legacy(origin_circuit_t *circ, const uint8_t *rend_cell_body)
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{
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crypt_path_t *hop = NULL;
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char keys[DIGEST_LEN+CPATH_KEY_MATERIAL_LEN];
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/* first DH_KEY_LEN bytes are g^y from the service. Finish the dh
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* handshake...*/
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tor_assert(circ->build_state);
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tor_assert(circ->build_state->pending_final_cpath);
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hop = circ->build_state->pending_final_cpath;
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tor_assert(hop->rend_dh_handshake_state);
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if (crypto_dh_compute_secret(LOG_PROTOCOL_WARN, hop->rend_dh_handshake_state,
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(char*)rend_cell_body, DH_KEY_LEN,
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keys, DIGEST_LEN+CPATH_KEY_MATERIAL_LEN)<0) {
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log_warn(LD_GENERAL, "Couldn't complete DH handshake.");
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goto err;
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}
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/* ... and set up cpath. */
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if (circuit_init_cpath_crypto(hop, keys+DIGEST_LEN, 0, 0)<0)
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goto err;
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/* Check whether the digest is right... */
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if (tor_memneq(keys, rend_cell_body+DH_KEY_LEN, DIGEST_LEN)) {
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log_warn(LD_PROTOCOL, "Incorrect digest of key material.");
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goto err;
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}
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/* clean up the crypto stuff we just made */
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crypto_dh_free(hop->rend_dh_handshake_state);
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hop->rend_dh_handshake_state = NULL;
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goto done;
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err:
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hop = NULL;
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done:
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memwipe(keys, 0, sizeof(keys));
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return hop;
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}
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/* Append the final <b>hop</b> to the cpath of the rend <b>circ</b>, and mark
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* <b>circ</b> ready for use to transfer HS relay cells. */
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static void
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finalize_rend_circuit(origin_circuit_t *circ, crypt_path_t *hop,
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int is_service_side)
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{
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tor_assert(circ);
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tor_assert(hop);
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/* Notify the circuit state machine that we are splicing this circuit */
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int new_circ_purpose = is_service_side ?
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CIRCUIT_PURPOSE_S_REND_JOINED : CIRCUIT_PURPOSE_C_REND_JOINED;
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circuit_change_purpose(TO_CIRCUIT(circ), new_circ_purpose);
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/* All is well. Extend the circuit. */
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hop->state = CPATH_STATE_OPEN;
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/* Set the windows to default. These are the windows that the client thinks
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* the service has. */
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hop->package_window = circuit_initial_package_window();
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hop->deliver_window = CIRCWINDOW_START;
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/* Now that this circuit has finished connecting to its destination,
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* make sure circuit_get_open_circ_or_launch is willing to return it
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* so we can actually use it. */
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circ->hs_circ_has_timed_out = 0;
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/* Append the hop to the cpath of this circuit */
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onion_append_to_cpath(&circ->cpath, hop);
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/* In legacy code, 'pending_final_cpath' points to the final hop we just
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* appended to the cpath. We set the original pointer to NULL so that we
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* don't double free it. */
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if (circ->build_state) {
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circ->build_state->pending_final_cpath = NULL;
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}
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/* Finally, mark circuit as ready to be used for client streams */
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if (!is_service_side) {
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circuit_try_attaching_streams(circ);
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}
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}
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/* Circuit <b>circ</b> just finished the rend ntor key exchange. Use the key
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* exchange output material at <b>ntor_key_seed</b> and setup <b>circ</b> to
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* serve as a rendezvous end-to-end circuit between the client and the
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* service. If <b>is_service_side</b> is set, then we are the hidden service
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* and the other side is the client.
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*
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* Return 0 if the operation went well; in case of error return -1. */
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int
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hs_circuit_setup_e2e_rend_circ(origin_circuit_t *circ,
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const uint8_t *ntor_key_seed,
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int is_service_side)
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{
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if (BUG(rend_circuit_validate_purpose(TO_CIRCUIT(circ)->purpose,
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is_service_side)) < 0) {
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return -1;
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}
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crypt_path_t *hop = get_rend_cpath(ntor_key_seed, is_service_side);
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if (!hop) {
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log_warn(LD_REND, "Couldn't get v3 %s cpath!",
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is_service_side ? "service-side" : "client-side");
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return -1;
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}
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finalize_rend_circuit(circ, hop, is_service_side);
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return 0;
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}
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/* We are a v2 legacy HS client and we just received a RENDEZVOUS1 cell
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* <b>rend_cell_body</b> on <b>circ</b>. Finish up the DH key exchange and then
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* extend the crypt path of <b>circ</b> so that the hidden service is on the
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* other side. */
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int
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hs_circuit_setup_e2e_rend_circ_legacy_client(origin_circuit_t *circ,
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const uint8_t *rend_cell_body)
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{
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if (BUG(rend_circuit_validate_purpose(TO_CIRCUIT(circ)->purpose, 0)) < 0) {
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return -1;
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}
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crypt_path_t *hop = get_rend_cpath_legacy(circ, rend_cell_body);
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if (!hop) {
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log_warn(LD_GENERAL, "Couldn't get v2 cpath.");
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return -1;
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}
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finalize_rend_circuit(circ, hop, 0);
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return 0;
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}
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23
src/or/hs_circuit.h
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23
src/or/hs_circuit.h
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@ -0,0 +1,23 @@
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/* Copyright (c) 2017, The Tor Project, Inc. */
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/* See LICENSE for licensing information */
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/**
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* \file hs_circuit.h
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* \brief Header file containing circuit data for the whole HS subsytem.
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**/
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#ifndef TOR_HS_CIRCUIT_H
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#define TOR_HS_CIRCUIT_H
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#include "or.h"
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/* e2e circuit API. */
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int hs_circuit_setup_e2e_rend_circ(origin_circuit_t *circ,
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const uint8_t *ntor_key_seed,
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int is_service_side);
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int hs_circuit_setup_e2e_rend_circ_legacy_client(origin_circuit_t *circ,
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const uint8_t *rend_cell_body);
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#endif /* TOR_HS_CIRCUIT_H */
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@ -53,6 +53,7 @@ LIBTOR_A_SOURCES = \
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src/or/hs_cache.c \
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src/or/hs_circuitmap.c \
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src/or/hs_common.c \
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src/or/hs_circuit.c \
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src/or/hs_descriptor.c \
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src/or/hs_ident.c \
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src/or/hs_intropoint.c \
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@ -182,6 +183,7 @@ ORHEADERS = \
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src/or/hibernate.h \
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src/or/hs_cache.h \
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src/or/hs_common.h \
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src/or/hs_circuit.h \
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src/or/hs_descriptor.h \
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src/or/hs_ident.h \
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src/or/hs_intropoint.h \
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@ -17,6 +17,7 @@
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#include "connection_edge.h"
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#include "directory.h"
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#include "hs_common.h"
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#include "hs_circuit.h"
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#include "main.h"
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#include "networkstatus.h"
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#include "nodelist.h"
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@ -1150,9 +1151,6 @@ int
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rend_client_receive_rendezvous(origin_circuit_t *circ, const uint8_t *request,
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size_t request_len)
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{
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crypt_path_t *hop;
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char keys[DIGEST_LEN+CPATH_KEY_MATERIAL_LEN];
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if ((circ->base_.purpose != CIRCUIT_PURPOSE_C_REND_READY &&
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circ->base_.purpose != CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED)
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|| !circ->build_state->pending_final_cpath) {
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@ -1170,55 +1168,13 @@ rend_client_receive_rendezvous(origin_circuit_t *circ, const uint8_t *request,
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log_info(LD_REND,"Got RENDEZVOUS2 cell from hidden service.");
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/* first DH_KEY_LEN bytes are g^y from the service. Finish the dh
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* handshake...*/
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tor_assert(circ->build_state);
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tor_assert(circ->build_state->pending_final_cpath);
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hop = circ->build_state->pending_final_cpath;
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tor_assert(hop->rend_dh_handshake_state);
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if (crypto_dh_compute_secret(LOG_PROTOCOL_WARN,
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hop->rend_dh_handshake_state, (char*)request,
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DH_KEY_LEN,
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keys, DIGEST_LEN+CPATH_KEY_MATERIAL_LEN)<0) {
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log_warn(LD_GENERAL, "Couldn't complete DH handshake.");
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if (hs_circuit_setup_e2e_rend_circ_legacy_client(circ, request) < 0) {
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log_warn(LD_GENERAL, "Failed to setup circ");
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goto err;
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}
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/* ... and set up cpath. */
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if (circuit_init_cpath_crypto(hop, keys+DIGEST_LEN, 0, 0)<0)
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goto err;
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/* Check whether the digest is right... */
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if (tor_memneq(keys, request+DH_KEY_LEN, DIGEST_LEN)) {
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log_warn(LD_PROTOCOL, "Incorrect digest of key material.");
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goto err;
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}
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crypto_dh_free(hop->rend_dh_handshake_state);
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hop->rend_dh_handshake_state = NULL;
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/* All is well. Extend the circuit. */
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circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_C_REND_JOINED);
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hop->state = CPATH_STATE_OPEN;
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/* set the windows to default. these are the windows
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* that the client thinks the service has.
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*/
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hop->package_window = circuit_initial_package_window();
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hop->deliver_window = CIRCWINDOW_START;
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/* Now that this circuit has finished connecting to its destination,
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* make sure circuit_get_open_circ_or_launch is willing to return it
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* so we can actually use it. */
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circ->hs_circ_has_timed_out = 0;
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onion_append_to_cpath(&circ->cpath, hop);
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circ->build_state->pending_final_cpath = NULL; /* prevent double-free */
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circuit_try_attaching_streams(circ);
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memwipe(keys, 0, sizeof(keys));
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return 0;
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err:
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memwipe(keys, 0, sizeof(keys));
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circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);
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return -1;
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}
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