Merge branch 'tor-github/pr/1925' (1797d051) · Commits · The Tor Project / Core / Tor

changes/bug30992

0 → 100644

+4 −0

Original line number	Diff line number	Diff line
		o Minor bugfixes (circuitpadding):
		- Add a per-circuit padding machine instance counter, so we can
		differentiate between shutdown requests for old machines on a circuit;
		Fixes bug 30992; bugfix on 0.4.1.1-alpha.

src/core/or/circuit_st.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -238,6 +238,12 @@ struct circuit_t {
		* Each element of this array corresponds to a different padding machine,
		* and we can have up to CIRCPAD_MAX_MACHINES such machines. */
		struct circpad_machine_runtime_t *padding_info[CIRCPAD_MAX_MACHINES];

		/** padding_machine_ctr increments each time a new padding machine
		* is negotiated. It is used for shutdown conditions, to ensure
		* that STOP commands actually correspond to the current machine,
		* and not a previous one. */
		uint32_t padding_machine_ctr;
		};

		#endif /* !defined(CIRCUIT_ST_H) */

src/core/or/circuitpadding.c

+85 −28

Original line number	Diff line number	Diff line
		@@ -266,19 +266,32 @@ circpad_marked_circuit_for_padding(circuit_t *circ, int reason)
		/**
		* Free all the machineinfos in <b>circ</b> that match <b>machine_num</b>.
		*
		* If machine_ctr is non-zero, also make sure it matches the padding_info's
		* machine counter before freeing.
		*
		* Returns true if any machineinfos with that number were freed.
		* False otherwise. */
		static int
		free_circ_machineinfos_with_machine_num(circuit_t *circ, int machine_num)
		free_circ_machineinfos_with_machine_num(circuit_t *circ, int machine_num,
		uint32_t machine_ctr)
		{
		int found = 0;
		FOR_EACH_CIRCUIT_MACHINE_BEGIN(i) {
		if (circ->padding_machine[i] &&
		circ->padding_machine[i]->machine_num == machine_num) {
		/* If machine_ctr is non-zero, make sure it matches too. This
		* is to ensure that old STOP messages don't shutdown newer machines. */
		if (machine_ctr && circ->padding_info[i] &&
		circ->padding_info[i]->machine_ctr != machine_ctr) {
		log_info(LD_CIRC,
		"Padding shutdown for wrong (old?) machine ctr: %u vs %u",
		machine_ctr, circ->padding_info[i]->machine_ctr);
		} else {
		circpad_circuit_machineinfo_free_idx(circ, i);
		circ->padding_machine[i] = NULL;
		found = 1;
		}
		}
		} FOR_EACH_CIRCUIT_MACHINE_END;

		return found;
		@@ -306,6 +319,7 @@ circpad_circuit_machineinfo_new(circuit_t *on_circ, int machine_index)
		mi->machine_index = machine_index;
		mi->on_circ = on_circ;
		mi->last_cell_time_sec = approx_time();
		mi->machine_ctr = on_circ->padding_machine_ctr;

		return mi;
		}
		@@ -1556,19 +1570,23 @@ circpad_machine_spec_transitioned_to_end(circpad_machine_runtime_t *mi)
		/* We free the machine info here so that we can be replaced
		* by a different machine. But we must leave the padding_machine
		* in place to wait for the negotiated response */
		uint32_t machine_ctr = mi->machine_ctr;
		circpad_circuit_machineinfo_free_idx(on_circ,
		machine->machine_index);
		circpad_negotiate_padding(TO_ORIGIN_CIRCUIT(on_circ),
		machine->machine_num,
		machine->target_hopnum,
		CIRCPAD_COMMAND_STOP);
		CIRCPAD_COMMAND_STOP,
		machine_ctr);
		} else {
		uint32_t machine_ctr = mi->machine_ctr;
		circpad_circuit_machineinfo_free_idx(on_circ,
		machine->machine_index);
		circpad_padding_negotiated(on_circ,
		machine->machine_num,
		CIRCPAD_COMMAND_STOP,
		CIRCPAD_RESPONSE_OK);
		CIRCPAD_RESPONSE_OK,
		machine_ctr);
		on_circ->padding_machine[machine->machine_index] = NULL;
		}
		}
		@@ -2099,13 +2117,15 @@ circpad_shutdown_old_machines(origin_circuit_t *on_circ)
		FOR_EACH_ACTIVE_CIRCUIT_MACHINE_BEGIN(i, circ) {
		if (!circpad_machine_conditions_met(on_circ,
		circ->padding_machine[i])) {
		uint32_t machine_ctr = circ->padding_info[i]->machine_ctr;
		// Clear machineinfo (frees timers)
		circpad_circuit_machineinfo_free_idx(circ, i);
		// Send padding negotiate stop
		circpad_negotiate_padding(on_circ,
		circ->padding_machine[i]->machine_num,
		circ->padding_machine[i]->target_hopnum,
		CIRCPAD_COMMAND_STOP);
		CIRCPAD_COMMAND_STOP,
		machine_ctr);
		}
		} FOR_EACH_ACTIVE_CIRCUIT_MACHINE_END;
		}
		@@ -2172,7 +2192,8 @@ circpad_add_matching_machines(origin_circuit_t *on_circ,
		circpad_setup_machine_on_circ(circ, machine);
		if (circpad_negotiate_padding(on_circ, machine->machine_num,
		machine->target_hopnum,
		CIRCPAD_COMMAND_START) < 0) {
		CIRCPAD_COMMAND_START,
		circ->padding_machine_ctr) < 0) {
		log_info(LD_CIRC,
		"Padding not negotiated. Cleaning machine from circuit %u",
		CIRCUIT_IS_ORIGIN(circ) ?
		@@ -2463,6 +2484,17 @@ circpad_setup_machine_on_circ(circuit_t *on_circ,
		machine->name, on_circ->purpose);
		}

		/* Padding machine ctr starts at 1, so we increment this ctr first.
		* (machine ctr of 0 means "any machine").
		*
		* See https://bugs.tororject.org/30992. */
		on_circ->padding_machine_ctr++;

		/* uint32 wraparound check: 0 is special, just wrap to 1 */
		if (on_circ->padding_machine_ctr == 0) {
		on_circ->padding_machine_ctr = 1;
		}

		on_circ->padding_info[machine->machine_index] =
		circpad_circuit_machineinfo_new(on_circ, machine->machine_index);
		on_circ->padding_machine[machine->machine_index] = machine;
		@@ -2816,7 +2848,8 @@ signed_error_t
		circpad_negotiate_padding(origin_circuit_t *circ,
		circpad_machine_num_t machine,
		uint8_t target_hopnum,
		uint8_t command)
		uint8_t command,
		uint32_t machine_ctr)
		{
		circpad_negotiate_t type;
		cell_t cell;
		@@ -2838,14 +2871,16 @@ circpad_negotiate_padding(origin_circuit_t *circ,
		circpad_negotiate_set_command(&type, command);
		circpad_negotiate_set_version(&type, 0);
		circpad_negotiate_set_machine_type(&type, machine);
		circpad_negotiate_set_machine_ctr(&type, machine_ctr);

		if ((len = circpad_negotiate_encode(cell.payload, CELL_PAYLOAD_SIZE,
		&type)) < 0)
		return -1;

		log_fn(LOG_INFO,LD_CIRC,
		"Negotiating padding on circuit %u (%d), command %d",
		circ->global_identifier, TO_CIRCUIT(circ)->purpose, command);
		"Negotiating padding on circuit %u (%d), command %d, for ctr %u",
		circ->global_identifier, TO_CIRCUIT(circ)->purpose, command,
		machine_ctr);

		return circpad_send_command_to_hop(circ, target_hopnum,
		RELAY_COMMAND_PADDING_NEGOTIATE,
		@@ -2861,7 +2896,8 @@ bool
		circpad_padding_negotiated(circuit_t *circ,
		circpad_machine_num_t machine,
		uint8_t command,
		uint8_t response)
		uint8_t response,
		uint32_t machine_ctr)
		{
		circpad_negotiated_t type;
		cell_t cell;
		@@ -2878,6 +2914,7 @@ circpad_padding_negotiated(circuit_t *circ,
		circpad_negotiated_set_response(&type, response);
		circpad_negotiated_set_version(&type, 0);
		circpad_negotiated_set_machine_type(&type, machine);
		circpad_negotiated_set_machine_ctr(&type, machine_ctr);

		if ((len = circpad_negotiated_encode(cell.payload, CELL_PAYLOAD_SIZE,
		&type)) < 0)
		@@ -2923,19 +2960,33 @@ circpad_handle_padding_negotiate(circuit_t circ, cell_t cell)
		if (negotiate->command == CIRCPAD_COMMAND_STOP) {
		/* Free the machine corresponding to this machine type */
		if (free_circ_machineinfos_with_machine_num(circ,
		negotiate->machine_type)) {
		log_info(LD_CIRC, "Received STOP command for machine %u",
		negotiate->machine_type);
		negotiate->machine_type,
		negotiate->machine_ctr)) {
		log_info(LD_CIRC, "Received STOP command for machine %u, ctr %u",
		negotiate->machine_type, negotiate->machine_ctr);
		goto done;
		}
		if (negotiate->machine_ctr <= circ->padding_machine_ctr) {
		log_info(LD_CIRC, "Received STOP command for old machine %u, ctr %u",
		negotiate->machine_type, negotiate->machine_ctr);
		goto done;

		} else {
		log_fn(LOG_PROTOCOL_WARN, LD_CIRC,
		"Received circuit padding stop command for unknown machine.");
		goto err;
		}
		} else if (negotiate->command == CIRCPAD_COMMAND_START) {
		SMARTLIST_FOREACH_BEGIN(relay_padding_machines,
		const circpad_machine_spec_t *, m) {
		if (m->machine_num == negotiate->machine_type) {
		circpad_setup_machine_on_circ(circ, m);
		if (negotiate->machine_ctr &&
		circ->padding_machine_ctr != negotiate->machine_ctr) {
		log_fn(LOG_PROTOCOL_WARN, LD_CIRC,
		"Client and relay have different counts for padding machines: "
		"%u vs %u", circ->padding_machine_ctr, negotiate->machine_ctr);
		}
		circpad_cell_event_nonpadding_received(circ);
		goto done;
		}
		@@ -2948,7 +2999,8 @@ circpad_handle_padding_negotiate(circuit_t circ, cell_t cell)
		done:
		circpad_padding_negotiated(circ, negotiate->machine_type,
		negotiate->command,
		(retval == 0) ? CIRCPAD_RESPONSE_OK : CIRCPAD_RESPONSE_ERR);
		(retval == 0) ? CIRCPAD_RESPONSE_OK : CIRCPAD_RESPONSE_ERR,
		negotiate->machine_ctr);
		circpad_negotiate_free(negotiate);

		return retval;
		@@ -2999,18 +3051,23 @@ circpad_handle_padding_negotiated(circuit_t circ, cell_t cell,
		* circpad_add_matching_matchines() added a new machine,
		* there may be a padding_machine for a different machine num
		* than this response. */
		free_circ_machineinfos_with_machine_num(circ, negotiated->machine_type);
		free_circ_machineinfos_with_machine_num(circ, negotiated->machine_type,
		negotiated->machine_ctr);
		} else if (negotiated->command == CIRCPAD_COMMAND_START &&
		negotiated->response == CIRCPAD_RESPONSE_ERR) {
		// This can happen due to consensus drift.. free the machines
		// This can still happen due to consensus drift.. free the machines
		// and be sad
		free_circ_machineinfos_with_machine_num(circ, negotiated->machine_type);
		if (free_circ_machineinfos_with_machine_num(circ, negotiated->machine_type,
		negotiated->machine_ctr)) {
		// Only fail if a machine was there and matched the error cell
		TO_ORIGIN_CIRCUIT(circ)->padding_negotiation_failed = 1;
		log_fn(LOG_PROTOCOL_WARN, LD_CIRC,
		"Middle node did not accept our padding request on circuit %u (%d)",
		"Middle node did not accept our padding request on circuit "
		"%u (%d)",
		TO_ORIGIN_CIRCUIT(circ)->global_identifier,
		circ->purpose);
		}
		}

		circpad_negotiated_free(negotiated);
		return 0;

src/core/or/circuitpadding.h

+11 −2

Original line number	Diff line number	Diff line
		@@ -565,6 +565,13 @@ typedef struct circpad_machine_runtime_t {
		/** What state is this machine in? */
		circpad_statenum_t current_state;

		/** Machine counter, for shutdown sync.
		*
		* Set from circuit_t.padding_machine_ctr, which is incremented each
		* padding machine instantiation.
		*/
		uint32_t machine_ctr;

		/**
		* True if we have scheduled a timer for padding.
		*
		@@ -726,11 +733,13 @@ signed_error_t circpad_handle_padding_negotiated(struct circuit_t *circ,
		signed_error_t circpad_negotiate_padding(struct origin_circuit_t *circ,
		circpad_machine_num_t machine,
		uint8_t target_hopnum,
		uint8_t command);
		uint8_t command,
		uint32_t machine_ctr);
		bool circpad_padding_negotiated(struct circuit_t *circ,
		circpad_machine_num_t machine,
		uint8_t command,
		uint8_t response);
		uint8_t response,
		uint32_t machine_ctr);

		circpad_purpose_mask_t circpad_circ_purpose_to_mask(uint8_t circ_purpose);

src/test/test_circuitpadding.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -1361,7 +1361,7 @@ test_circuitpadding_wronghop(void *arg)

		/* 5. Test that asking to stop the wrong machine does nothing */
		circpad_negotiate_padding(TO_ORIGIN_CIRCUIT(client_side),
		255, 2, CIRCPAD_COMMAND_STOP);
		255, 2, CIRCPAD_COMMAND_STOP, 0);
		tt_ptr_op(client_side->padding_machine[0], OP_NE, NULL);
		tt_ptr_op(client_side->padding_info[0], OP_NE, NULL);
		tt_ptr_op(relay_side->padding_machine[0], OP_NE, NULL);
		@@ -1409,7 +1409,7 @@ test_circuitpadding_wronghop(void *arg)
		circpad_padding_negotiated(relay_side,
		CIRCPAD_MACHINE_CIRC_SETUP,
		CIRCPAD_COMMAND_START,
		CIRCPAD_RESPONSE_OK);
		CIRCPAD_RESPONSE_OK, 0);

		/* verify no padding was negotiated */
		tt_ptr_op(relay_side->padding_machine[0], OP_EQ, NULL);
		@@ -1418,7 +1418,7 @@ test_circuitpadding_wronghop(void *arg)
		circpad_padding_negotiated(relay_side,
		CIRCPAD_MACHINE_CIRC_SETUP,
		CIRCPAD_COMMAND_START,
		CIRCPAD_RESPONSE_ERR);
		CIRCPAD_RESPONSE_ERR, 0);

		/* verify no padding was negotiated */
		tt_ptr_op(relay_side->padding_machine[0], OP_EQ, NULL);
		@@ -1521,7 +1521,7 @@ test_circuitpadding_negotiation(void *arg)
		/* Force negotiate padding. */
		circpad_negotiate_padding(TO_ORIGIN_CIRCUIT(client_side),
		CIRCPAD_MACHINE_CIRC_SETUP,
		2, CIRCPAD_COMMAND_START);
		2, CIRCPAD_COMMAND_START, 0);

		/* verify no padding was negotiated */
		tt_ptr_op(relay_side->padding_machine[0], OP_EQ, NULL);