Commit b2b77922 authored by Nick Mathewson's avatar Nick Mathewson 🦀
Browse files

Merge remote-tracking branch 'tor-github/pr/1033'

parents 9cec7a7b 84274000

changes/ticket28634

0 → 100644
+10 −0
Original line number Diff line number Diff line 
  o Major features (Circuit padding):

    - Onion service clients will now add padding cells to the initial portions

      of their INTRODUCE and RENDEZVOUS circuits, to make those circuits'

      traffic patterns look more like general purpose Exit traffic. The

      overhead for this is 2 extra cells in each direction for RENDEZVOUS

      circuits, and 1 extra upstream cell and 10 downstream cells for INTRODUCE

      circuits. This will only be enabled if the circuit's middle node supports

      this feature, too. (Clients may specify fixed middle nodes with the MiddleNodes

      torrc directive, and may force-disable this feature with the CircuitPadding

      torrc directive). Closes ticket 28634.

scripts/maint/practracker/exceptions.txt

+2 −0
Original line number Diff line number Diff line
@@ -290,3 +290,5 @@ problem function-size /src/tools/tor-resolve.c:build_socks5_resolve_request() 10 
problem function-size /src/tools/tor-resolve.c:do_resolve() 175

problem function-size /src/tools/tor-resolve.c:main() 112

problem function-size /src/core/or/circuitpadding.c:circpad_machine_schedule_padding() 107

problem function-size /src/core/or/circuitpadding_machines.c:circpad_machine_relay_hide_intro_circuits() 104

problem function-size /src/core/or/circuitpadding_machines.c:circpad_machine_client_hide_rend_circuits() 112

src/app/main/shutdown.c

+1 −0
Original line number Diff line number Diff line
@@ -139,6 +139,7 @@ tor_free_all(int postfork) 
  dos_free_all();

  circuitmux_ewma_free_all();

  accounting_free_all();

  circpad_free_all();



  if (!postfork) {

    config_free_all();

src/core/include.am

+2 −0
Original line number Diff line number Diff line
@@ -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			\

src/core/or/circuitpadding.c

+118 −84
Original line number Diff line number Diff line
@@ -37,6 +37,13 @@ 
 * When a padding machine reaches the END state, it gets wiped from the circuit

 * so that other padding machines can take over if needed (see

 * circpad_machine_spec_transitioned_to_end()).

 *

 ****************************

 * General notes:

 *

 * All used machines should be heap allocated and placed into

 * origin_padding_machines/relay_padding_machines so that they get correctly

 * cleaned up by the circpad_free_all() function.

 **/



#define CIRCUITPADDING_PRIVATE
@@ -46,6 +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"
@@ -72,8 +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,
@@ -125,34 +131,6 @@ STATIC smartlist_t *relay_padding_machines = NULL; 
    continue;

#define FOR_EACH_ACTIVE_CIRCUIT_MACHINE_END } STMT_END ;



/**

 * Return a human-readable description for a circuit padding state.

 */

static const char *

circpad_state_to_string(circpad_statenum_t state)

{

  const char *descr;



  switch (state) {

  case CIRCPAD_STATE_START:

    descr = "START";

    break;

  case CIRCPAD_STATE_BURST:

    descr = "BURST";

    break;

  case CIRCPAD_STATE_GAP:

    descr = "GAP";

    break;

  case CIRCPAD_STATE_END:

    descr = "END";

    break;

  default:

    descr = "CUSTOM"; // XXX: Just return # in static char buf?

  }



  return descr;

}



/**

 * Free the machineinfo at an index

 */
@@ -485,7 +463,10 @@ 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);
@@ -525,9 +506,14 @@ circpad_choose_state_length(circpad_machine_runtime_t *mi) 
  length = circpad_distribution_sample(state->length_dist);

  length = MAX(0, length);

  length += state->start_length;



  if (state->max_length) {

    length = MIN(length, state->max_length);

  }



  mi->state_length = clamp_double_to_int64(length);



  log_info(LD_CIRC, "State length sampled to %"PRIu64".", mi->state_length);

}



/**
@@ -595,6 +581,11 @@ circpad_machine_sample_delay(circpad_machine_runtime_t *mi) 
    histogram_total_tokens = state->histogram_total_tokens;

  }



  /* If we are out of tokens, don't schedule padding. */

  if (!histogram_total_tokens) {

    return CIRCPAD_DELAY_INFINITE;

  }



  bin_choice = crypto_fast_rng_get_uint64(get_thread_fast_rng(),

                                          histogram_total_tokens);
@@ -897,7 +888,7 @@ circpad_machine_remove_closest_token(circpad_machine_runtime_t *mi, 
      bin_to_remove = lower;

    }

    mi->histogram[bin_to_remove]--;

    log_debug(LD_GENERAL, "Removing token from bin %d", bin_to_remove);

    log_debug(LD_CIRC, "Removing token from bin %d", bin_to_remove);

    return;

  } else {

    if (current - lower > higher - current) {
@@ -1207,14 +1198,16 @@ circpad_send_padding_cell_for_callback(circpad_machine_runtime_t *mi) 
    circpad_send_command_to_hop(TO_ORIGIN_CIRCUIT(mi->on_circ),

                                CIRCPAD_GET_MACHINE(mi)->target_hopnum,

                                RELAY_COMMAND_DROP, NULL, 0);

    log_fn(LOG_INFO,LD_CIRC, "Callback: Sending padding to origin circuit %u.",

           TO_ORIGIN_CIRCUIT(mi->on_circ)->global_identifier);

    log_info(LD_CIRC, "Callback: Sending padding to origin circuit %u"

             " (%d) [length: %"PRIu64"]",

             TO_ORIGIN_CIRCUIT(mi->on_circ)->global_identifier,

             mi->on_circ->purpose, mi->state_length);

  } else {

    // If we're a non-origin circ, we can just send from here as if we're the

    // edge.

    if (TO_OR_CIRCUIT(circ)->p_chan_cells.n <= circpad_max_circ_queued_cells) {

      log_fn(LOG_INFO,LD_CIRC,

             "Callback: Sending padding to non-origin circuit.");

      log_info(LD_CIRC, "Callback: Sending padding to circuit (%d)"

               " [length: %"PRIu64"]", mi->on_circ->purpose, mi->state_length);

      relay_send_command_from_edge(0, mi->on_circ, RELAY_COMMAND_DROP, NULL,

                                   0, NULL);

      rep_hist_padding_count_write(PADDING_TYPE_DROP);
@@ -1582,9 +1575,8 @@ circpad_machine_spec_transition,(circpad_machine_runtime_t *mi, 
     * a transition to itself. All non-specified events are ignored.

     */

    log_fn(LOG_INFO, LD_CIRC,

           "Circpad machine %d transitioning from %s to %s",

            mi->machine_index, circpad_state_to_string(mi->current_state),

            circpad_state_to_string(s));

           "Circpad machine %d transitioning from %u to %u",

           mi->machine_index, mi->current_state, s);



    /* If this is not the same state, switch and init tokens,

     * otherwise just reschedule padding. */
@@ -1734,13 +1726,12 @@ circpad_estimate_circ_rtt_on_send(circuit_t *circ, 
     * to back. Stop estimating RTT in this case. Note that we only

     * stop RTT update if the circuit is opened, to allow for RTT estimates

     * of var cells during circ setup. */

    mi->stop_rtt_update = 1;



    if (!mi->rtt_estimate_usec) {

    if (!mi->rtt_estimate_usec && !mi->stop_rtt_update) {

      static ratelim_t rtt_lim = RATELIM_INIT(600);

      log_fn_ratelim(&rtt_lim,LOG_NOTICE,LD_BUG,

        "Circuit sent two cells back to back before estimating RTT.");

    }

    mi->stop_rtt_update = 1;

  }

}
@@ -1976,7 +1967,6 @@ 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)

{
@@ -2019,7 +2009,8 @@ circpad_shutdown_old_machines(origin_circuit_t *on_circ) 
}



/**

 * Negotiate new machines that would apply to this circuit.

 * Negotiate new machines that would apply to this circuit, given the machines

 * inside <b>machines_sl</b>.

 *

 * This function checks to see if we have any free machine indexes,

 * and for each free machine index, it initializes the most recently
@@ -2027,14 +2018,15 @@ circpad_shutdown_old_machines(origin_circuit_t *on_circ) 
 * index and circuit conditions, and negotiates it with the appropriate

 * middle relay.

 */

static void

circpad_add_matching_machines(origin_circuit_t *on_circ)

STATIC void

circpad_add_matching_machines(origin_circuit_t *on_circ,

                              smartlist_t *machines_sl)

{

  circuit_t *circ = TO_CIRCUIT(on_circ);



#ifdef TOR_UNIT_TESTS

  /* Tests don't have to init our padding machines */

  if (!origin_padding_machines)

  if (!machines_sl)

    return;

#endif
@@ -2051,7 +2043,7 @@ circpad_add_matching_machines(origin_circuit_t *on_circ) 
    /* We have a free machine index. Check the origin padding

     * machines in reverse order, so that more recently added

     * machines take priority over older ones. */

    SMARTLIST_FOREACH_REVERSE_BEGIN(origin_padding_machines,

    SMARTLIST_FOREACH_REVERSE_BEGIN(machines_sl,

                                    circpad_machine_spec_t *,

                                    machine) {

      /* Machine definitions have a specific target machine index.
@@ -2079,6 +2071,7 @@ circpad_add_matching_machines(origin_circuit_t *on_circ) 
        if (circpad_negotiate_padding(on_circ, machine->machine_num,

                                  machine->target_hopnum,

                                  CIRCPAD_COMMAND_START) < 0) {

          log_info(LD_CIRC, "Padding not negotiated. Cleaning machine");

          circpad_circuit_machineinfo_free_idx(circ, i);

          circ->padding_machine[i] = NULL;

          on_circ->padding_negotiation_failed = 1;
@@ -2102,7 +2095,7 @@ circpad_machine_event_circ_added_hop(origin_circuit_t *on_circ) 
{

  /* Since our padding conditions do not specify a max_hops,

   * all we can do is add machines here */

  circpad_add_matching_machines(on_circ);

  circpad_add_matching_machines(on_circ, origin_padding_machines);

}



/**
@@ -2115,7 +2108,7 @@ void 
circpad_machine_event_circ_built(origin_circuit_t *circ)

{

  circpad_shutdown_old_machines(circ);

  circpad_add_matching_machines(circ);

  circpad_add_matching_machines(circ, origin_padding_machines);

}



/**
@@ -2128,7 +2121,7 @@ void 
circpad_machine_event_circ_purpose_changed(origin_circuit_t *circ)

{

  circpad_shutdown_old_machines(circ);

  circpad_add_matching_machines(circ);

  circpad_add_matching_machines(circ, origin_padding_machines);

}



/**
@@ -2142,7 +2135,7 @@ void 
circpad_machine_event_circ_has_no_relay_early(origin_circuit_t *circ)

{

  circpad_shutdown_old_machines(circ);

  circpad_add_matching_machines(circ);

  circpad_add_matching_machines(circ, origin_padding_machines);

}



/**
@@ -2157,7 +2150,7 @@ void 
circpad_machine_event_circ_has_streams(origin_circuit_t *circ)

{

  circpad_shutdown_old_machines(circ);

  circpad_add_matching_machines(circ);

  circpad_add_matching_machines(circ, origin_padding_machines);

}



/**
@@ -2172,7 +2165,7 @@ void 
circpad_machine_event_circ_has_no_streams(origin_circuit_t *circ)

{

  circpad_shutdown_old_machines(circ);

  circpad_add_matching_machines(circ);

  circpad_add_matching_machines(circ, origin_padding_machines);

}



/**
@@ -2253,13 +2246,6 @@ circpad_deliver_recognized_relay_cell_events(circuit_t *circ, 
                                             uint8_t relay_command,

                                             crypt_path_t *layer_hint)

{

  /* Padding negotiate cells are ignored by the state machines

   * for simplicity. */

  if (relay_command == RELAY_COMMAND_PADDING_NEGOTIATE ||

      relay_command == RELAY_COMMAND_PADDING_NEGOTIATED) {

    return;

  }



  if (relay_command == RELAY_COMMAND_DROP) {

    rep_hist_padding_count_read(PADDING_TYPE_DROP);
@@ -2296,16 +2282,12 @@ void 
circpad_deliver_sent_relay_cell_events(circuit_t *circ,

                                       uint8_t relay_command)

{

  /* Padding negotiate cells are ignored by the state machines

   * for simplicity. */

  if (relay_command == RELAY_COMMAND_PADDING_NEGOTIATE ||

      relay_command == RELAY_COMMAND_PADDING_NEGOTIATED) {

    return;

  }



  /* RELAY_COMMAND_DROP is the multi-hop (aka circuit-level) padding cell in

   * tor. (CELL_PADDING is a channel-level padding cell, which is not relayed

   * or processed here) */

   * or processed here).

   *

   * We do generate events for PADDING_NEGOTIATE and PADDING_NEGOTIATED cells.

   */

  if (relay_command == RELAY_COMMAND_DROP) {

    /* Optimization: The event for RELAY_COMMAND_DROP is sent directly

     * from circpad_send_padding_cell_for_callback(). This is to avoid
@@ -2363,12 +2345,21 @@ circpad_setup_machine_on_circ(circuit_t *on_circ, 
                      == NULL);

  tor_assert_nonfatal(on_circ->padding_info[machine->machine_index] == NULL);



  /* Log message */

  if (CIRCUIT_IS_ORIGIN(on_circ)) {

    log_info(LD_CIRC, "Registering machine %s to origin circ %u (%d)",

             machine->name,

             TO_ORIGIN_CIRCUIT(on_circ)->global_identifier, on_circ->purpose);

  } else {

    log_info(LD_CIRC, "Registering machine %s to non-origin circ (%d)",

             machine->name, on_circ->purpose);

  }



  on_circ->padding_info[machine->machine_index] =

      circpad_circuit_machineinfo_new(on_circ, machine->machine_index);

  on_circ->padding_machine[machine->machine_index] = machine;

}



#ifdef TOR_UNIT_TESTS

/** Validate a single state of a padding machine */

static bool

padding_machine_state_is_valid(const circpad_state_t *state)
@@ -2384,7 +2375,7 @@ padding_machine_state_is_valid(const circpad_state_t *state) 


  /* We need at least two bins in a histogram */

  if (state->histogram_len < 2) {

    log_warn(LD_GENERAL, "You can't have a histogram with less than 2 bins");

    log_warn(LD_CIRC, "You can't have a histogram with less than 2 bins");

    return false;

  }
@@ -2394,7 +2385,7 @@ padding_machine_state_is_valid(const circpad_state_t *state) 
    /* Check that histogram edges are strictly increasing. Ignore the first

     * edge since it can be zero. */

    if (prev_bin_edge >= state->histogram_edges[b] && b > 0) {

      log_warn(LD_GENERAL, "Histogram edges are not increasing [%u/%u]",

      log_warn(LD_CIRC, "Histogram edges are not increasing [%u/%u]",

               prev_bin_edge, state->histogram_edges[b]);

      return false;

    }
@@ -2406,7 +2397,7 @@ padding_machine_state_is_valid(const circpad_state_t *state) 
  }

  /* Verify that the total number of tokens is correct */

  if (tokens_count != state->histogram_total_tokens) {

    log_warn(LD_GENERAL, "Histogram token count is wrong [%u/%u]",

    log_warn(LD_CIRC, "Histogram token count is wrong [%u/%u]",

             tokens_count, state->histogram_total_tokens);

    return false;

  }
@@ -2432,12 +2423,12 @@ padding_machine_is_valid(const circpad_machine_spec_t *machine) 


/* Validate and register <b>machine</b> into <b>machine_list</b>. If

 * <b>machine_list</b> is NULL, then just validate. */

STATIC void

register_padding_machine(circpad_machine_spec_t *machine,

void

circpad_register_padding_machine(circpad_machine_spec_t *machine,

                                 smartlist_t *machine_list)

{

  if (!padding_machine_is_valid(machine)) {

    log_warn(LD_GENERAL, "Machine #%u is invalid. Ignoring.",

    log_warn(LD_CIRC, "Machine #%u is invalid. Ignoring.",

             machine->machine_num);

    return;

  }
@@ -2447,6 +2438,7 @@ register_padding_machine(circpad_machine_spec_t *machine, 
  }

}



#ifdef TOR_UNIT_TESTS

/* These padding machines are only used for tests pending #28634. */

static void

circpad_circ_client_machine_init(void)
@@ -2499,7 +2491,8 @@ circpad_circ_client_machine_init(void) 
  circ_client_machine->states[CIRCPAD_STATE_BURST].histogram_total_tokens = 5;



  circ_client_machine->machine_num = smartlist_len(origin_padding_machines);

  register_padding_machine(circ_client_machine, origin_padding_machines);

  circpad_register_padding_machine(circ_client_machine,

                                   origin_padding_machines);

}



static void
@@ -2599,7 +2592,8 @@ circpad_circ_responder_machine_init(void) 
      CIRCPAD_TOKEN_REMOVAL_CLOSEST_USEC;



  circ_responder_machine->machine_num = smartlist_len(relay_padding_machines);

  register_padding_machine(circ_responder_machine, relay_padding_machines);

  circpad_register_padding_machine(circ_responder_machine,

                                   relay_padding_machines);

}

#endif
@@ -2618,6 +2612,14 @@ 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();
@@ -2668,8 +2670,8 @@ circpad_node_supports_padding(const node_t *node) 
 * Returns node_t from the consensus for that hop, if it is opened.

 * Otherwise returns NULL.

 */

static const node_t *

circuit_get_nth_node(origin_circuit_t *circ, int hop)

MOCK_IMPL(STATIC const node_t *,

circuit_get_nth_node,(origin_circuit_t *circ, int hop))

{

  crypt_path_t *iter = circuit_get_cpath_hop(circ, hop);
@@ -2732,8 +2734,8 @@ circpad_negotiate_padding(origin_circuit_t *circ, 
        &type)) < 0)

    return -1;



  log_fn(LOG_INFO,LD_CIRC, "Negotiating padding on circuit %u",

         circ->global_identifier);

  log_fn(LOG_INFO,LD_CIRC, "Negotiating padding on circuit %u (%d)",

         circ->global_identifier, TO_CIRCUIT(circ)->purpose);



  return circpad_send_command_to_hop(circ, target_hopnum,

                                     RELAY_COMMAND_PADDING_NEGOTIATE,
@@ -2818,6 +2820,7 @@ circpad_handle_padding_negotiate(circuit_t *circ, cell_t *cell) 
                            const circpad_machine_spec_t *, m) {

      if (m->machine_num == negotiate->machine_type) {

        circpad_setup_machine_on_circ(circ, m);

        circpad_cell_event_nonpadding_received(circ);

        goto done;

      }

    } SMARTLIST_FOREACH_END(m);
@@ -2871,6 +2874,7 @@ 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,
@@ -2891,6 +2895,36 @@ circpad_handle_padding_negotiated(circuit_t *circ, cell_t *cell, 
  return 0;

}



/** Free memory allocated by this machine spec. */

STATIC void

machine_spec_free_(circpad_machine_spec_t *m)

{

  if (!m) return;



  tor_free(m->states);

  tor_free(m);

}



/** Free all memory allocated by the circuitpadding subsystem. */

void

circpad_free_all(void)

{

  if (origin_padding_machines) {

    SMARTLIST_FOREACH_BEGIN(origin_padding_machines,

                            circpad_machine_spec_t *, m) {

      machine_spec_free(m);

    } SMARTLIST_FOREACH_END(m);

    smartlist_free(origin_padding_machines);

  }

  if (relay_padding_machines) {

    SMARTLIST_FOREACH_BEGIN(relay_padding_machines,

                            circpad_machine_spec_t *, m) {

      machine_spec_free(m);

    } SMARTLIST_FOREACH_END(m);

    smartlist_free(relay_padding_machines);

  }

}



/* Serialization */

// TODO: Should we use keyword=value here? Are there helpers for that?

#if 0