[tor-commits] [tor/master] prop224: Introduce e2e rendezvous circuit code.
nickm at torproject.org
nickm at torproject.org
Fri Jul 7 15:19:28 UTC 2017
commit 0cb66fc900f5198fb063454801af3b4b22867e50
Author: David Goulet <dgoulet at torproject.org>
Date: Fri May 12 12:00:43 2017 -0400
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 at torproject.org>
---
src/or/hs_circuit.c | 215 ++++++++++++++++++++++++++++++++++++++++++++++++++++
src/or/hs_circuit.h | 23 ++++++
src/or/include.am | 2 +
src/or/rendclient.c | 52 +------------
4 files changed, 244 insertions(+), 48 deletions(-)
diff --git a/src/or/hs_circuit.c b/src/or/hs_circuit.c
new file mode 100644
index 0000000..f8c95f7
--- /dev/null
+++ b/src/or/hs_circuit.c
@@ -0,0 +1,215 @@
+/* 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;
+}
+
diff --git a/src/or/hs_circuit.h b/src/or/hs_circuit.h
new file mode 100644
index 0000000..1c2924c
--- /dev/null
+++ b/src/or/hs_circuit.h
@@ -0,0 +1,23 @@
+/* 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 */
+
diff --git a/src/or/include.am b/src/or/include.am
index e800db5..18868e4 100644
--- a/src/or/include.am
+++ b/src/or/include.am
@@ -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 \
diff --git a/src/or/rendclient.c b/src/or/rendclient.c
index 3cf67b5..3d160bd 100644
--- a/src/or/rendclient.c
+++ b/src/or/rendclient.c
@@ -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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