commit ac895fa40552b78744eddfb648dadde23834e553 Author: George Kadianakis desnacked@riseup.net Date: Thu May 16 14:02:16 2019 +0300

Add client-side onion service circuit hiding machines. --- src/core/include.am | 2 + src/core/or/circuitpadding.c | 18 +- src/core/or/circuitpadding.h | 5 + src/core/or/circuitpadding_machines.c | 418 ++++++++++++++++++++++++++++++++++ src/core/or/circuitpadding_machines.h | 35 +++ src/test/test_circuitpadding.c | 188 +++++++++++++++ 6 files changed, 662 insertions(+), 4 deletions(-)

diff --git a/src/core/include.am b/src/core/include.am index f722b7048..66ce2c965 100644 --- a/src/core/include.am +++ b/src/core/include.am @@ -37,6 +37,7 @@ LIBTOR_APP_A_SOURCES = \ src/core/or/circuitmux.c \ src/core/or/circuitmux_ewma.c \ src/core/or/circuitpadding.c \ + src/core/or/circuitpadding_machines.c \ src/core/or/circuitstats.c \ src/core/or/circuituse.c \ src/core/or/crypt_path.c \ @@ -247,6 +248,7 @@ noinst_HEADERS += \ src/core/or/circuitmux_ewma.h \ src/core/or/circuitstats.h \ src/core/or/circuitpadding.h \ + src/core/or/circuitpadding_machines.h \ src/core/or/circuituse.h \ src/core/or/command.h \ src/core/or/connection_edge.h \ diff --git a/src/core/or/circuitpadding.c b/src/core/or/circuitpadding.c index e02cfb7bc..6c48bbe6f 100644 --- a/src/core/or/circuitpadding.c +++ b/src/core/or/circuitpadding.c @@ -53,6 +53,7 @@ #include "lib/math/prob_distr.h" #include "core/or/or.h" #include "core/or/circuitpadding.h" +#include "core/or/circuitpadding_machines.h" #include "core/or/circuitlist.h" #include "core/or/circuituse.h" #include "core/mainloop/netstatus.h" @@ -79,8 +80,6 @@

#include "app/config/config.h"

-static inline circpad_purpose_mask_t circpad_circ_purpose_to_mask(uint8_t - circ_purpose); static inline circpad_circuit_state_t circpad_circuit_state( origin_circuit_t *circ); static void circpad_setup_machine_on_circ(circuit_t *on_circ, @@ -492,7 +491,10 @@ circpad_machine_setup_tokens(circpad_machine_runtime_t *mi) const circpad_state_t *state = circpad_machine_current_state(mi);

/* If this state doesn't exist, or doesn't have token removal, - * free any previous state's histogram, and bail */ + * free any previous state's runtime histogram, and bail. + * + * If we don't have a token removal strategy, we also don't need a runtime + * histogram and we rely on the immutable one in machine_spec_t. */ if (!state || state->token_removal == CIRCPAD_TOKEN_REMOVAL_NONE) { if (mi->histogram) { tor_free(mi->histogram); @@ -1990,7 +1992,6 @@ circpad_circuit_state(origin_circuit_t *circ) * Convert a normal circuit purpose into a bitmask that we can * use for determining matching circuits. */ -static inline circpad_purpose_mask_t circpad_circ_purpose_to_mask(uint8_t circ_purpose) { @@ -2623,6 +2624,14 @@ circpad_machines_init(void) origin_padding_machines = smartlist_new(); relay_padding_machines = smartlist_new();

+ /* Register machines for hiding client-side intro circuits */ + circpad_machine_client_hide_intro_circuits(origin_padding_machines); + circpad_machine_relay_hide_intro_circuits(relay_padding_machines); + + /* Register machines for hiding client-side rendezvous circuits */ + circpad_machine_client_hide_rend_circuits(origin_padding_machines); + circpad_machine_relay_hide_rend_circuits(relay_padding_machines); + // TODO: Parse machines from consensus and torrc #ifdef TOR_UNIT_TESTS circpad_circ_client_machine_init(); @@ -2877,6 +2886,7 @@ circpad_handle_padding_negotiated(circuit_t *circ, cell_t *cell, }

if (negotiated->command == CIRCPAD_COMMAND_STOP) { + log_info(LD_CIRC, "Received STOP command on PADDING_NEGOTIATED"); /* There may not be a padding_info here if we shut down the * machine in circpad_shutdown_old_machines(). Or, if * circpad_add_matching_matchines() added a new machine, diff --git a/src/core/or/circuitpadding.h b/src/core/or/circuitpadding.h index c7c5f6c69..37b4603f0 100644 --- a/src/core/or/circuitpadding.h +++ b/src/core/or/circuitpadding.h @@ -603,6 +603,9 @@ typedef uint8_t circpad_machine_num_t;

/** Global state machine structure from the consensus */ typedef struct circpad_machine_spec_t { + /* Just a user-friendly machine name for logs */ + const char *name; + /** Global machine number */ circpad_machine_num_t machine_num;

@@ -728,6 +731,8 @@ bool circpad_padding_negotiated(struct circuit_t *circ, uint8_t command, uint8_t response);

+circpad_purpose_mask_t circpad_circ_purpose_to_mask(uint8_t circ_purpose); + MOCK_DECL(circpad_decision_t, circpad_machine_schedule_padding,(circpad_machine_runtime_t *));

diff --git a/src/core/or/circuitpadding_machines.c b/src/core/or/circuitpadding_machines.c new file mode 100644 index 000000000..4d348f959 --- /dev/null +++ b/src/core/or/circuitpadding_machines.c @@ -0,0 +1,418 @@ +/* Copyright (c) 2019 The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file circuitpadding_machines.c + * \brief Circuit padding state machines + * + * \detail + * + * Introduce circuit padding machines that will be used by Tor circuits, as + * specified by proposal 302 "Hiding onion service clients using padding". + * + * Right now this file introduces two machines that aim to hide the client-side + * of onion service circuits against naive classifiers like the ones from the + * "Circuit Fingerprinting Attacks: Passive Deanonymization of Tor Hidden + * Services" paper from USENIX. By naive classifiers we mean classifiers that + * use basic features like "circuit construction circuits" and "incoming and + * outgoing cell counts" and "duration of activity". + * + * In particular, these machines aim to be lightweight and protect against + * these basic classifiers. They don't aim to protect against more advanced + * attacks that use deep learning or even correlate various circuit + * construction events together. Machines that fool such advanced classifiers + * are also possible, but they can't be so lightweight and might require more + * WTF-PAD features. So for now we opt for the following two machines: + * + * Client-side introduction circuit hiding machine: + * + * This machine hides client-side introduction circuits by making their + * circuit consruction sequence look like normal general circuits that + * download directory information. Furthermore, the circuits are kept open + * until all the padding has been sent, since intro circuits are usually + * very short lived and this act as a distinguisher. For more info see + * circpad_machine_client_hide_intro_circuits() and the sec. + * + * Client-side rendezvous circuit hiding machine: + * + * This machine hides client-side rendezvous circuits by making their + * circuit construction sequence look like normal general circuits. For more + * details see circpad_machine_client_hide_rend_circuits() and the spec. + * + * TODO: These are simple machines that carefully manipulate the cells of the + * initial circuit setup procedure to make them look like general + * circuits. In the future, more states can be baked into their state machine + * to do more advanced obfuscation. + **/ + +#define CIRCUITPADDING_MACHINES_PRIVATE + +#include "core/or/or.h" +#include "feature/nodelist/networkstatus.h" + +#include "lib/crypt_ops/crypto_rand.h" + +#include "core/or/circuitlist.h" + +#include "core/or/circuitpadding_machines.h" +#include "core/or/circuitpadding.h" + +/* Setup the simple state machine we use for all HS padding machines */ +static void +setup_state_machine_for_hiding_intro_circuits(circpad_machine_spec_t *machine) +{ + /* Two states: START, OBFUSCATE_CIRC_SETUP (and END) */ + circpad_machine_states_init(machine, 2); + + /* For the relay-side machine, we want to transition + * START -> OBFUSCATE_CIRC_SETUP upon first non-padding + * cell sent (PADDING_NEGOTIATED in this case). + * + * For the origin-side machine, we transition to OBFUSCATE_CIRC_SETUP after + * sending PADDING_NEGOTIATE, and we stay there (without sending any padding) + * until we receive a STOP from the other side. */ + machine->states[CIRCPAD_STATE_START]. + next_state[CIRCPAD_EVENT_NONPADDING_SENT] = + CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP; + + /* For the relay-side, we want to transition from OBFUSCATE_CIRC_SETUP to END + * state when the length finishes. + * + * For the origin-side, we don't care because the relay-side machine is gonna + * END us. */ + machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP]. + next_state[CIRCPAD_EVENT_LENGTH_COUNT] = CIRCPAD_STATE_END; + + /* Now let's define the OBF -> OBF transitions that maintain our padding + * flow: + * + * For the relay-side machine, we want to keep on sending padding bytes even + * when nothing else happens on this circuit. */ + machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP]. + next_state[CIRCPAD_EVENT_PADDING_SENT] = + CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP; + /* For the relay-side machine, we need this transition so that we re-enter + the state, after PADDING_NEGOTIATED is sent. Otherwise, the remove token + function will disable the timer, and nothing will restart it since there + is no other motion on an intro circuit. */ + machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP]. + next_state[CIRCPAD_EVENT_NONPADDING_SENT] = + CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP; +} + +/* Setup the OBFUSCATE_CIRC_SETUP state of the machine that hides client-side + * intro circuits. */ +static void +setup_obf_state_for_hiding_intro_circuits(circpad_state_t *obf_state, + bool is_client) +{ + /* Token removal strategy for OBFUSCATE_CIRC_SETUP state. We pick the + * simplest one since we rely on the state length sampling and not the + * tokens. */ + obf_state->token_removal = CIRCPAD_TOKEN_REMOVAL_NONE; + + /* Figure out the length of the OBFUSCATE_CIRC_SETUP state so that it's + * randomized. We will set the histogram such that we don't send any padding + * from the origin-side, so just tune these parameteres for the + * relay-side. */ + obf_state->length_dist.type = CIRCPAD_DIST_UNIFORM; + obf_state->length_dist.param1 = INTRO_MACHINE_MINIMUM_PADDING; + obf_state->length_dist.param2 = INTRO_MACHINE_MAXIMUM_PADDING; + + /* Configure histogram */ + obf_state->histogram_len = 2; + if (is_client) { + /* For the origin-side machine we don't want to send any padding, so setup + * infinite delays. */ + obf_state->histogram_edges[0] = CIRCPAD_DELAY_INFINITE-1; + obf_state->histogram_edges[1] = CIRCPAD_DELAY_INFINITE; + /* zero tokens */ + obf_state->histogram[0] = 0; + } else { + /* For the relay-side machine we want to batch padding instantly to pretend + * its an incoming directory download. So set the histogram edges tight: + * (1, 10ms, infinity). */ + obf_state->histogram_edges[0] = 1000; + obf_state->histogram_edges[1] = 10000; + /* padding is controlled by state length, so this is just a high value */ + obf_state->histogram[0] = 1000; + } + + /* just one bin, so setup the total tokens */ + obf_state->histogram_total_tokens = obf_state->histogram[0]; +} + +/** Create a client-side padding machine that aims to hide IP circuits. In + * particular, it keeps intro circuits alive until a bunch of fake traffic has + * been pushed through. + */ +void +circpad_machine_client_hide_intro_circuits(smartlist_t *machines_sl) +{ + circpad_machine_spec_t *client_machine + = tor_malloc_zero(sizeof(circpad_machine_spec_t)); + + client_machine->name = "client_ip_circ"; + + client_machine->conditions.state_mask = CIRCPAD_CIRC_OPENED; + client_machine->target_hopnum = 2; + + /* This is a client machine */ + client_machine->is_origin_side = 1; + + /* We only want to pad introduction circuits, and we want to start padding + * only after the INTRODUCE1 cell has been sent, so set the purposes + * appropriately. + * + * In particular we want introduction circuits to blend as much as possible + * with general circuits. Most general circuits have the following initial + * relay cell sequence (outgoing cells marked in [brackets]): + * + * [EXTEND2] -> EXTENDED2 -> [EXTEND2] -> EXTENDED2 -> [BEGIN] -> CONNECTED + * -> [DATA] -> [DATA] -> DATA -> DATA...(inbound data cells continue) + * + * Whereas normal introduction circuits usually look like: + * + * [EXTEND2] -> EXTENDED2 -> [EXTEND2] -> EXTENDED2 -> [EXTEND2] -> EXTENDED2 + * -> [INTRO1] -> INTRODUCE_ACK + * + * This means that up to the sixth cell (first line of each sequence above), + * both general and intro circuits have identical cell sequences. After that + * we want to mimic the second line sequence of + * -> [DATA] -> [DATA] -> DATA -> DATA...(inbound data cells continue) + * + * We achieve this by starting padding INTRODUCE1 has been sent. With padding + * negotiation cells, in the common case of the second line looks like: + * -> [INTRO1] -> [PADDING_NEGOTIATE] -> PADDING_NEGOTIATED -> INTRO_ACK + * + * Then, the middle node will send between INTRO_MACHINE_MINIMUM_PADDING and + * INTRO_MACHINE_MAXIMUM_PADDING cells, to match the "...(inbound data cells + * continue)" portion of the trace (aka the rest of an HTTPS response body). + */ + client_machine->conditions.purpose_mask = + circpad_circ_purpose_to_mask(CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT)| + circpad_circ_purpose_to_mask(CIRCUIT_PURPOSE_C_INTRODUCE_ACKED)| + circpad_circ_purpose_to_mask(CIRCUIT_PURPOSE_C_CIRCUIT_PADDING); + + /* Keep the circuit alive even after the introduction has been finished, + * otherwise the short-term lifetime of the circuit will blow our cover */ + client_machine->manage_circ_lifetime = 1; + + /* Set padding machine limits to help guard against excessive padding */ + client_machine->allowed_padding_count = INTRO_MACHINE_MAXIMUM_PADDING; + client_machine->max_padding_percent = 1; + + /* Setup states and histograms */ + setup_state_machine_for_hiding_intro_circuits(client_machine); + setup_obf_state_for_hiding_intro_circuits( + &client_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP], + true); + + /* Register the machine */ + client_machine->machine_num = smartlist_len(machines_sl); + circpad_register_padding_machine(client_machine, machines_sl); + + log_warn(LD_GENERAL, + "Registered client intro point hiding padding machine (%u)", + client_machine->machine_num); +} + +/** Create a relay-side padding machine that aims to hide IP circuits. See + * comments on the function above for more details on the workings of the + * machine. */ +void +circpad_machine_relay_hide_intro_circuits(smartlist_t *machines_sl) +{ + circpad_machine_spec_t *relay_machine + = tor_malloc_zero(sizeof(circpad_machine_spec_t)); + + relay_machine->name = "relay_ip_circ"; + + relay_machine->conditions.state_mask = CIRCPAD_CIRC_OPENED; + relay_machine->target_hopnum = 2; + + /* This is a relay-side machine */ + relay_machine->is_origin_side = 0; + + /* We want to negotiate END from this side after all our padding is done, so + * that the origin-side machine goes into END state, and eventually closes + * the circuit. */ + relay_machine->should_negotiate_end = 1; + + /* Set padding machine limits to help guard against excessive padding */ + relay_machine->allowed_padding_count = INTRO_MACHINE_MAXIMUM_PADDING; + relay_machine->max_padding_percent = 1; + + /* Setup states and histograms */ + setup_state_machine_for_hiding_intro_circuits(relay_machine); + setup_obf_state_for_hiding_intro_circuits( + &relay_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP], + false); + + /* Register the machine */ + relay_machine->machine_num = smartlist_len(machines_sl); + circpad_register_padding_machine(relay_machine, machines_sl); + + log_warn(LD_GENERAL, + "Registered relay intro circuit hiding padding machine (%u)", + relay_machine->machine_num); +} + +/************************** Rendezvous-circuit machine ***********************/ + +/* Setup the obf state of the machine that hides client-side rend + * circuits. */ +static void +setup_obf_state_for_hiding_rend_circuits(circpad_state_t *obf_state) +{ + /* Don't use a token removal strategy since we don't want to use monotime + functions. We want this machine to be light. */ + obf_state->token_removal = CIRCPAD_TOKEN_REMOVAL_NONE; + + /* Instead, to control the volume of padding (we just want to send a single + * padding cell) we will use a static state length. We just want one token, + * since we want to make the following pattern: + * [PADDING_NEGOTIATE] -> [DROP] -> PADDING_NEGOTIATED -> DROP */ + obf_state->length_dist.type = CIRCPAD_DIST_UNIFORM; + obf_state->length_dist.param1 = 1; + obf_state->length_dist.param2 = 2; + + /* Histogram is: (0 msecs, 50 msecs, infinity). We want this to be fast so + * that the incoming PADDING_NEGOTIATED cell always arrives after the + * outgoing [DROP]. */ + obf_state->histogram_len = 2; + obf_state->histogram_edges[0] = 0; + obf_state->histogram_edges[1] = 1000; + + /* dummy amount of tokens. they don't matter. we rely on state length. */ + obf_state->histogram[0] = 1; + obf_state->histogram_total_tokens = 1; +} + +/* Setup the simple state machine we use for all HS padding machines */ +static void +setup_state_machine_for_hiding_rend_circuits(circpad_machine_spec_t *machine) +{ + /* Two states: START, OBFUSCATE_CIRC_SETUP (and END) */ + circpad_machine_states_init(machine, 2); + + /* START -> OBFUSCATE_CIRC_SETUP transition upon sending the first + * non-padding cell (which is PADDING_NEGOTIATE) */ + machine->states[CIRCPAD_STATE_START]. + next_state[CIRCPAD_EVENT_NONPADDING_SENT] = + CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP; + + /* OBFUSCATE_CIRC_SETUP -> END transition when we finish all the tokens */ + machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP]. + next_state[CIRCPAD_EVENT_PADDING_RECV] = CIRCPAD_STATE_END; + machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP]. + next_state[CIRCPAD_EVENT_LENGTH_COUNT] = CIRCPAD_STATE_END; +} + +/** Create a client-side padding machine that aims to hide rendezvous + * circuits.*/ +void +circpad_machine_client_hide_rend_circuits(smartlist_t *machines_sl) +{ + circpad_machine_spec_t *client_machine + = tor_malloc_zero(sizeof(circpad_machine_spec_t)); + + client_machine->name = "client_rp_circ"; + + /* Only pad after the circuit has been built and pad to the middle */ + client_machine->conditions.state_mask = CIRCPAD_CIRC_OPENED; + client_machine->target_hopnum = 2; + + /* This is a client machine */ + client_machine->is_origin_side = 1; + + /* We only want to pad rendezvous circuits, and we want to start padding only + * after the rendezvous circuit has been established. + * + * Following a similar argument as for intro circuits, we are aiming for + * padded rendezvous circuits to blend in with the initial cell sequence of + * general circuits which usually look like this: + * + * [EXTEND2] -> EXTENDED2 -> [EXTEND2] -> EXTENDED2 -> [BEGIN] -> CONNECTED + * -> [DATA] -> [DATA] -> DATA -> DATA...(incoming cells continue) + * + * Whereas normal rendezvous circuits usually look like: + * + * [EXTEND2] -> EXTENDED2 -> [EXTEND2] -> EXTENDED2 -> [EST_REND] -> REND_EST + * -> REND2 -> [BEGIN] + * + * This means that up to the sixth cell (in the first line), both general and + * rend circuits have identical cell sequences. + * + * After that we want to mimic a [DATA] -> [DATA] -> DATA -> DATA sequence. + * + * With padding negotiation right after the REND_ESTABLISHED, the sequence + * becomes: + * + * [EXTEND2] -> EXTENDED2 -> [EXTEND2] -> EXTENDED2 -> [EST_REND] -> REND_EST + * -> [PADDING_NEGOTIATE] -> [DROP] -> PADDING_NEGOTIATED -> DROP... + * + * After which normal application DATA cells continue on the circuit. + * + * Hence this way we make rendezvous circuits look like general circuits up + * till the end of the circuit setup. */ + client_machine->conditions.purpose_mask = + circpad_circ_purpose_to_mask(CIRCUIT_PURPOSE_C_REND_JOINED)| + circpad_circ_purpose_to_mask(CIRCUIT_PURPOSE_C_REND_READY)| + circpad_circ_purpose_to_mask(CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED); + + /* Set padding machine limits to help guard against excessive padding */ + client_machine->allowed_padding_count = 1; + client_machine->max_padding_percent = 1; + + /* Setup states and histograms */ + setup_state_machine_for_hiding_rend_circuits(client_machine); + setup_obf_state_for_hiding_rend_circuits( + &client_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP]); + + /* Register the machine */ + client_machine->machine_num = smartlist_len(machines_sl); + circpad_register_padding_machine(client_machine, machines_sl); + + log_warn(LD_GENERAL, + "Registered client rendezvous circuit hiding padding machine (%u)", + client_machine->machine_num); +} + +/** Create a relay-side padding machine that aims to hide IP circuits. + * + * This is meant to follow the client-side machine. + */ +void +circpad_machine_relay_hide_rend_circuits(smartlist_t *machines_sl) +{ + circpad_machine_spec_t *relay_machine + = tor_malloc_zero(sizeof(circpad_machine_spec_t)); + + relay_machine->name = "relay_rp_circ"; + + /* Only pad after the circuit has been built and pad to the middle */ + relay_machine->conditions.min_hops = 2; + relay_machine->conditions.state_mask = CIRCPAD_CIRC_OPENED; + relay_machine->target_hopnum = 2; + + /* This is a relay-side machine */ + relay_machine->is_origin_side = 0; + + /* Set padding machine limits to help guard against excessive padding */ + relay_machine->allowed_padding_count = 1; + relay_machine->max_padding_percent = 1; + + /* Setup states and histograms */ + setup_state_machine_for_hiding_rend_circuits(relay_machine); + setup_obf_state_for_hiding_rend_circuits( + &relay_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP]); + + /* Register the machine */ + relay_machine->machine_num = smartlist_len(machines_sl); + circpad_register_padding_machine(relay_machine, machines_sl); + + log_warn(LD_GENERAL, + "Registered relay rendezvous circuit hiding padding machine (%u)", + relay_machine->machine_num); +} diff --git a/src/core/or/circuitpadding_machines.h b/src/core/or/circuitpadding_machines.h new file mode 100644 index 000000000..c44a70f2c --- /dev/null +++ b/src/core/or/circuitpadding_machines.h @@ -0,0 +1,35 @@ +/* Copyright (c) 2018 The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file circuitpadding_machines.h + * \brief Header file for circuitpadding_machines.c. + **/ + +#ifndef TOR_CIRCUITPADDING_MACHINES_H +#define TOR_CIRCUITPADDING_MACHINES_H + +void circpad_machine_relay_hide_intro_circuits(smartlist_t *machines_sl); +void circpad_machine_client_hide_intro_circuits(smartlist_t *machines_sl); +void circpad_machine_relay_hide_rend_circuits(smartlist_t *machines_sl); +void circpad_machine_client_hide_rend_circuits(smartlist_t *machines_sl); + +#ifdef CIRCUITPADDING_MACHINES_PRIVATE + +/** State of the padding machines that actually sends padding */ +#define CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP CIRCPAD_STATE_BURST + +/** Constants defining the amount of padding that a machine will send to hide + * HS circuits. The actual value is sampled uniformly random between the + * min/max values. + */ + +/** Minimum number of relay-side padding cells to be sent by this machine */ +#define INTRO_MACHINE_MINIMUM_PADDING 7 +/** Maximum number of relay-side padding cells to be sent by this machine. + * The actual value will be sampled between the min and max.*/ +#define INTRO_MACHINE_MAXIMUM_PADDING 10 + +#endif + +#endif diff --git a/src/test/test_circuitpadding.c b/src/test/test_circuitpadding.c index c5aad0f5d..7835b438f 100644 --- a/src/test/test_circuitpadding.c +++ b/src/test/test_circuitpadding.c @@ -415,6 +415,8 @@ helper_create_basic_machine(void) /* Start, burst */ circpad_machine_states_init(&circ_client_machine, 2);

+ circ_client_machine.name = "basic"; + circ_client_machine.states[CIRCPAD_STATE_START]. next_state[CIRCPAD_EVENT_NONPADDING_RECV] = CIRCPAD_STATE_BURST; circ_client_machine.states[CIRCPAD_STATE_START].use_rtt_estimate = 1; @@ -2917,6 +2919,192 @@ test_circuitpadding_manage_circuit_lifetime(void *arg) UNMOCK(tor_gettimeofday); }

+/** Helper for the test_circuitpadding_hs_machines test: + * + * - Create a client and relay circuit. + * - Setup right circuit purpose and attach a machine to the client circuit. + * - Verify that state transitions work as intended and state length gets + * enforced. + * + * This function is able to do this test both for intro and rend circuits + * depending on the value of <b>test_intro_circs</b>. + */ +static void +helper_test_hs_machines(bool test_intro_circs) +{ + /* Setup the circuits */ + origin_circuit_t *origin_client_side = origin_circuit_new(); + client_side = TO_CIRCUIT(origin_client_side); + client_side->purpose = CIRCUIT_PURPOSE_C_GENERAL; + + dummy_channel.cmux = circuitmux_alloc(); + relay_side = TO_CIRCUIT(new_fake_orcirc(&dummy_channel, &dummy_channel)); + relay_side->purpose = CIRCUIT_PURPOSE_OR; + + /* extend the client circ to two hops */ + simulate_single_hop_extend(client_side, relay_side, 1); + simulate_single_hop_extend(client_side, relay_side, 1); + + /* machines only apply on opened circuits */ + origin_client_side->has_opened = 1; + + /************************************/ + + /* Attaching the client machine now won't work here because of a wrong + * purpose */ + tt_assert(!client_side->padding_machine[0]); + circpad_add_matching_machines(origin_client_side, origin_padding_machines); + tt_assert(!client_side->padding_machine[0]); + + /* Change the purpose, see the machine getting attached */ + client_side->purpose = test_intro_circs ? + CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT : CIRCUIT_PURPOSE_C_REND_JOINED; + circpad_add_matching_machines(origin_client_side, origin_padding_machines); + tt_ptr_op(client_side->padding_info[0], OP_NE, NULL); + tt_ptr_op(client_side->padding_machine[0], OP_NE, NULL); + + tt_ptr_op(relay_side->padding_info[0], OP_NE, NULL); + tt_ptr_op(relay_side->padding_machine[0], OP_NE, NULL); + + /* Verify that the right machine is attached */ + tt_str_op(client_side->padding_machine[0]->name, OP_EQ, + test_intro_circs ? "client_ip_circ" : "client_rp_circ"); + tt_str_op(relay_side->padding_machine[0]->name, OP_EQ, + test_intro_circs ? "relay_ip_circ": "relay_rp_circ"); + + /***********************************/ + + /* Intro machines are at START state, but rend machines have already skipped + * to OBFUSCATE_CIRC_SETUP because of the sent PADDING_NEGOTIATE. */ + tt_int_op(client_side->padding_info[0]->current_state, OP_EQ, + CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP); + tt_int_op(relay_side->padding_info[0]->current_state, OP_EQ, + CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP); + + /*Send non-padding to move the machines from START to OBFUSCATE_CIRC_SETUP */ + circpad_cell_event_nonpadding_received(client_side); + circpad_cell_event_nonpadding_received(relay_side); + tt_int_op(client_side->padding_info[0]->current_state, OP_EQ, + CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP); + tt_int_op(relay_side->padding_info[0]->current_state, OP_EQ, + CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP); + + /* For rendezvous circuit machines we can stop early since are simpler than + * the intro circuit machines. */ + if (!test_intro_circs) { + tt_int_op(client_side->padding_info[0]->histogram[0], OP_EQ, 1); + goto done; + } + + /* Check that the state lengths have been sampled and are within range */ + circpad_machine_runtime_t *client_machine_runtime = + client_side->padding_info[0]; + circpad_machine_runtime_t *relay_machine_runtime = + relay_side->padding_info[0]; + if (test_intro_circs) { + tt_int_op(client_machine_runtime->state_length, OP_GE, + INTRO_MACHINE_MINIMUM_PADDING); + tt_int_op(client_machine_runtime->state_length, OP_LT, + INTRO_MACHINE_MAXIMUM_PADDING); + tt_int_op(relay_machine_runtime->state_length, OP_GE, + INTRO_MACHINE_MINIMUM_PADDING); + tt_int_op(relay_machine_runtime->state_length, OP_LT, + INTRO_MACHINE_MAXIMUM_PADDING); + } else { + tt_int_op(client_machine_runtime->state_length, OP_EQ, 1); + tt_int_op(relay_machine_runtime->state_length, OP_EQ, 1); + } + + /* Send state_length worth of padding and see that the state goes to END */ + int i; + for (i = (int) client_machine_runtime->state_length ; i > 0 ; i--) { + circpad_send_padding_cell_for_callback(client_machine_runtime); + } + /* See that the machine has been teared down after all the length has been + * exhausted. */ + tt_int_op(client_side->padding_info[0]->current_state, OP_EQ, + CIRCPAD_STATE_END); + + done: + free_fake_orcirc(relay_side); + circuitmux_detach_all_circuits(dummy_channel.cmux, NULL); + circuitmux_free(dummy_channel.cmux); + free_fake_origin_circuit(TO_ORIGIN_CIRCUIT(client_side)); +} + +/** Test that the HS circuit padding machines work as intended. */ +static void +test_circuitpadding_hs_machines(void *arg) +{ + (void)arg; + + /* Test logic: + * + * 1) Register the HS machines, which aim to hide the presense of + * onion service traffic on the client-side + * + * 2) Call helper_test_hs_machines() to perform tests for the intro circuit + * machines and for the rend circuit machines. + */ + + MOCK(circuitmux_attach_circuit, circuitmux_attach_circuit_mock); + MOCK(circuit_package_relay_cell, circuit_package_relay_cell_mock); + MOCK(circuit_get_nth_node, circuit_get_nth_node_mock); + MOCK(circpad_machine_schedule_padding,circpad_machine_schedule_padding_mock); + + origin_padding_machines = smartlist_new(); + relay_padding_machines = smartlist_new(); + + nodes_init(); + + monotime_init(); + monotime_enable_test_mocking(); + monotime_set_mock_time_nsec(1*TOR_NSEC_PER_USEC); + monotime_coarse_set_mock_time_nsec(1*TOR_NSEC_PER_USEC); + curr_mocked_time = 1*TOR_NSEC_PER_USEC; + + timers_initialize(); + + /* This is needed so that we are not considered to be dormant */ + note_user_activity(20); + + /************************************/ + + /* Register the HS machines */ + circpad_machine_client_hide_intro_circuits(origin_padding_machines); + circpad_machine_client_hide_rend_circuits(origin_padding_machines); + circpad_machine_relay_hide_intro_circuits(relay_padding_machines); + circpad_machine_relay_hide_rend_circuits(relay_padding_machines); + + /***********************************/ + + /* Do the tests for the intro circuit machines */ + helper_test_hs_machines(true); + /* Do the tests for the rend circuit machines */ + helper_test_hs_machines(false); + + timers_shutdown(); + monotime_disable_test_mocking(); + + SMARTLIST_FOREACH_BEGIN(origin_padding_machines, + circpad_machine_spec_t *, m) { + machine_spec_free(m); + } SMARTLIST_FOREACH_END(m); + + SMARTLIST_FOREACH_BEGIN(relay_padding_machines, + circpad_machine_spec_t *, m) { + machine_spec_free(m); + } SMARTLIST_FOREACH_END(m); + + smartlist_free(origin_padding_machines); + smartlist_free(relay_padding_machines); + + UNMOCK(circuitmux_attach_circuit); + UNMOCK(circuit_package_relay_cell); + UNMOCK(circuit_get_nth_node); + UNMOCK(circpad_machine_schedule_padding); +} + #define TEST_CIRCUITPADDING(name, flags) \ { #name, test_##name, (flags), NULL, NULL }