commit f697ac58610a74c1cbffd16b39e8e90d1592290f Author: Mike Perry mikeperry-git@torproject.org Date: Tue Jun 9 02:36:45 2020 -0500
Bug 32040: Add a keep_*_mask to keep circpad machines
Allows us to program machines that stay around after creation if circuit state or purpose changes. --- src/core/or/circuitpadding.c | 39 ++++++++++++++++++++++++++++------- src/core/or/circuitpadding.h | 14 +++++++++++-- src/core/or/circuitpadding_machines.c | 12 +++++------ 3 files changed, 50 insertions(+), 15 deletions(-)
diff --git a/src/core/or/circuitpadding.c b/src/core/or/circuitpadding.c index b958fec4f..889ffb03f 100644 --- a/src/core/or/circuitpadding.c +++ b/src/core/or/circuitpadding.c @@ -2008,7 +2008,7 @@ circpad_internal_event_state_length_up(circpad_machine_runtime_t *mi) * Returns true if the circuit matches the conditions. */ static inline bool -circpad_machine_conditions_met(origin_circuit_t *circ, +circpad_machine_conditions_apply(origin_circuit_t *circ, const circpad_machine_spec_t *machine) { /* If padding is disabled, no machines should match/apply. This has @@ -2025,7 +2025,7 @@ circpad_machine_conditions_met(origin_circuit_t *circ, }
if (!(circpad_circ_purpose_to_mask(TO_CIRCUIT(circ)->purpose) - & machine->conditions.purpose_mask)) + & machine->conditions.apply_purpose_mask)) return 0;
if (machine->conditions.requires_vanguards) { @@ -2041,7 +2041,7 @@ circpad_machine_conditions_met(origin_circuit_t *circ, * "I want to apply to circuits with either streams or no streams"; OR * "I only want to apply to circuits with streams"; OR * "I only want to apply to circuits without streams". */ - if (!(circpad_circuit_state(circ) & machine->conditions.state_mask)) + if (!(circpad_circuit_state(circ) & machine->conditions.apply_state_mask)) return 0;
if (circuit_get_cpath_opened_len(circ) < machine->conditions.min_hops) @@ -2050,6 +2050,26 @@ circpad_machine_conditions_met(origin_circuit_t *circ, return 1; }
+/** + * Check to see if any of the keep conditions still apply to this circuit. + * + * These conditions keep the machines active if they match, but do not + * cause new machines to start up. + */ +static inline bool +circpad_machine_conditions_keep(origin_circuit_t *circ, + const circpad_machine_spec_t *machine) +{ + if ((circpad_circ_purpose_to_mask(TO_CIRCUIT(circ)->purpose) + & machine->conditions.keep_purpose_mask)) + return 1; + + if ((circpad_circuit_state(circ) & machine->conditions.keep_state_mask)) + return 1; + + return 0; +} + /** * Returns a minimized representation of the circuit state. * @@ -2115,7 +2135,12 @@ circpad_shutdown_old_machines(origin_circuit_t *on_circ) circuit_t *circ = TO_CIRCUIT(on_circ);
FOR_EACH_ACTIVE_CIRCUIT_MACHINE_BEGIN(i, circ) { - if (!circpad_machine_conditions_met(on_circ, + /* We shut down a machine if neither the apply conditions + * nor the keep conditions match. If either set of conditions match, + * keep it around. */ + if (!circpad_machine_conditions_apply(on_circ, + circ->padding_machine[i]) && + !circpad_machine_conditions_keep(on_circ, circ->padding_machine[i])) { uint32_t machine_ctr = circ->padding_info[i]->machine_ctr; // Clear machineinfo (frees timers) @@ -2174,7 +2199,7 @@ circpad_add_matching_machines(origin_circuit_t *on_circ, * machines installed on a circuit. Make sure we only * add this machine if its target machine index is free. */ if (machine->machine_index == i && - circpad_machine_conditions_met(on_circ, machine)) { + circpad_machine_conditions_apply(on_circ, machine)) {
// We can only replace this machine if the target hopnum // is the same, otherwise we'll get invalid data @@ -2587,9 +2612,9 @@ circpad_circ_client_machine_init(void) = tor_malloc_zero(sizeof(circpad_machine_spec_t));
circ_client_machine->conditions.min_hops = 2; - circ_client_machine->conditions.state_mask = + circ_client_machine->conditions.apply_state_mask = CIRCPAD_CIRC_BUILDING|CIRCPAD_CIRC_OPENED|CIRCPAD_CIRC_HAS_RELAY_EARLY; - circ_client_machine->conditions.purpose_mask = CIRCPAD_PURPOSE_ALL; + circ_client_machine->conditions.apply_purpose_mask = CIRCPAD_PURPOSE_ALL; circ_client_machine->conditions.reduced_padding_ok = 1;
circ_client_machine->target_hopnum = 2; diff --git a/src/core/or/circuitpadding.h b/src/core/or/circuitpadding.h index 4fadcb742..3d2929cf7 100644 --- a/src/core/or/circuitpadding.h +++ b/src/core/or/circuitpadding.h @@ -173,11 +173,21 @@ typedef struct circpad_machine_conditions_t {
/** Only apply the machine *if* the circuit's state matches any of * the bits set in this bitmask. */ - circpad_circuit_state_t state_mask; + circpad_circuit_state_t apply_state_mask;
/** Only apply a machine *if* the circuit's purpose matches one * of the bits set in this bitmask */ - circpad_purpose_mask_t purpose_mask; + circpad_purpose_mask_t apply_purpose_mask; + + /** Keep a machine if any of the circuits's state machine's match + * the bits set in this bitmask, but don't apply new machines if + * they match this mask. */ + circpad_circuit_state_t keep_state_mask; + + /** Keep a machine if any of the circuits's state machine's match + * the bits set in this bitmask, but don't apply new machines if + * they match this mask. */ + circpad_purpose_mask_t keep_purpose_mask;
} circpad_machine_conditions_t;
diff --git a/src/core/or/circuitpadding_machines.c b/src/core/or/circuitpadding_machines.c index 98767f9e8..405af5061 100644 --- a/src/core/or/circuitpadding_machines.c +++ b/src/core/or/circuitpadding_machines.c @@ -67,7 +67,7 @@ circpad_machine_client_hide_intro_circuits(smartlist_t *machines_sl)
client_machine->name = "client_ip_circ";
- client_machine->conditions.state_mask = CIRCPAD_CIRC_OPENED; + client_machine->conditions.apply_state_mask = CIRCPAD_CIRC_OPENED; client_machine->target_hopnum = 2;
/* This is a client machine */ @@ -102,7 +102,7 @@ circpad_machine_client_hide_intro_circuits(smartlist_t *machines_sl) * 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 = + client_machine->conditions.apply_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); @@ -152,7 +152,7 @@ circpad_machine_relay_hide_intro_circuits(smartlist_t *machines_sl)
relay_machine->name = "relay_ip_circ";
- relay_machine->conditions.state_mask = CIRCPAD_CIRC_OPENED; + relay_machine->conditions.apply_state_mask = CIRCPAD_CIRC_OPENED;
/* This is a relay-side machine */ relay_machine->is_origin_side = 0; @@ -263,7 +263,7 @@ circpad_machine_client_hide_rend_circuits(smartlist_t *machines_sl) 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->conditions.apply_state_mask = CIRCPAD_CIRC_OPENED; client_machine->target_hopnum = 2;
/* This is a client machine */ @@ -299,7 +299,7 @@ circpad_machine_client_hide_rend_circuits(smartlist_t *machines_sl) * * Hence this way we make rendezvous circuits look like general circuits up * till the end of the circuit setup. */ - client_machine->conditions.purpose_mask = + client_machine->conditions.apply_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); @@ -383,7 +383,7 @@ circpad_machine_relay_hide_rend_circuits(smartlist_t *machines_sl)
/* 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->conditions.apply_state_mask = CIRCPAD_CIRC_OPENED;
/* This is a relay-side machine */ relay_machine->is_origin_side = 0;